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Oc
S 1 T 2 Group 2: Regional Anesthesia 1 of
Surgery 2
AY 2019- 2020
1 st^ Shifting Exam
Regional Anesthesia
Anita V. Ocampo-So, MD, DPBA
OUTLINE
I. Case Description II. Preoperative Assessment III. Preoperative Assessment specific for Regional Anesthesia IV. Premedications V. Regional Anesthesia VI. Methods of Neuraxial Block A. Review of Spinal Anatomy B. Mechanism of Action C. Clinical consideration D. Spinal Anesthesia E. Epidural Anesthesia F. Caudal Anesthesia VII. Method of choice pertinent to the case VIII. Intraoperative Assessment A. Fluid Management B. Intraoperative Complications IX. Post-operative Assessment X. Post operative complications and ADR XI. Discharge Criteria
Notes in orange dashed boxes were stressed by Dr. So!
I. CASE DESCRIPTION
A 22 year old male student was brought to the emergency room because of abdominal pain in the right lower quadrant associated with nausea and vomiting. He has not taken any meals the whole day, except for sips of water. He has no childhood diseases or allergies. He was booked for appendectomy. How will you anesthetize the patient?
Pertinent Findings: (+) Right lower quadrant abdominal pain (+) Nausea (+) Vomiting (+) Anorexia (-) Childhood diseases and allergies
II. PRE-OPERATIVE ASSESSMENT
A.HISTORY
A useful rule is never to place appendicitis lower than second in the differential diagnosis of acute abdominal pain in a previously healthy person. Classic pattern of migratory pain from periumbilical to right lower quadrant. Most reliable symptom. Pain usually followed by anorexia and nausea. Vomiting could also be associated symptoms.
B. PHYSICAL EXAMINATION
Temperature and pulse rate might be elevated slightly due to ongoing inflammation. Tenderness often maximal at or near the McBurney’s point.
Positive direct rebound and indirect rebound tenderness are both present. (+) Roving’s Sign (+) Psoas sign and (+) Dunphy’s sign.
C. ANCILLARY PROCEDURES AND LABORATORY
EXAMS
Laboratory Exams Mild leukocytosis ranging from 10,000–18,000/mm predominantly neutrophils. One of the signs of perforated appendix Urinalysis is not diagnostic for appendicitis but it is useful to rule out the urinary tract infection, pyelonephritis or nephrolithiasis Alvarado score and Appendicitis Inflammatory Response Score: clinical scoring system that can be used to diagnose appendicitis. Imaging Studies Plain films of the abdomen are rarely but can be used to rule out other pathology. Graded compression ultrasonography (ultrasound) is an inexpensive way of diagnosing acute appendicitis with high accuracy. High-resolution, helical, computed tomography is the most accurate imaging study but it is expensive. Diagnostic Laparoscopy can serve as both a diagnostic and therapeutic maneuver for patients with acute abdominal pain and suspected acute appendicitis.
III. PREOPERATIVE ASSESSMENT SPECIFIC FOR
REGIONAL ANESTHESIA
A. GOAL OF PREOPERATIVE ASSESSMENT
● Reduce the patient’s surgical and anesthetic perioperative morbidity or mortality ● Return the patient to desirable functioning as quickly as possible ● Should appear in the patient’s permanent medical record and describe pertinent findings like; → Medical history → Anesthetic history → Current medications → Physical examination → ASA physical status class → Laboratory results → Interpretation of imaging → Electrocardiograms → Comment when consultant’s recommendation will not be followed ● Preoperative note should briefly describe the following; → Anesthetic plan − Should indicate whether regional or general anesthesia will be used → Statement regarding informed consent from the patient or guardian ▪ Informed consent discussion indicating the plan, alternative plans, advantages and disadvantages
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▪ Indications that there are no interval changes since preoperative evaluation was performed
Preoperative Assessment
● Relevant anatomy should be examined ● Evidence of infection near the site of anatomic abnormalities may contraindicate the planned procedure ● Abbreviated neurological examination is important → serves to document whether any neurological deficits may be present before the block is performed ● Contraindications to spinal anesthesia → Patients in shock − Spinal anesthesia (SA) could cause preganglionic sympathetic blockade hypotension → Patients not yet fully resuscitated − SA could cause unanticipated cardiac arrest and bradycardia → Infection at the site of spinal needle placement − SA could introduce the bacteria to the CNS → Frank coagulopathy − SA could cause spinal haematoma formation leading to compression of the spinal cord and severe neurologic sequelae → Patient refusal → Convulsion or raised intracranial pressure due to brain tumor − Drainage of the lumbar cerebrospinal fluid (CSF) can increase the pressure gradient between the spinal, supratentorial and infratentorial compartments. This can result in rapid herniation of the brain stem or occluding hydrocephalus which leads to coma
Notes from Doc So: For patients with polio, let them sign a written consent that they are willing to undergo procedure using spinal anesthesia, because some of them will complain that their other leg got smaller after the procedure. To prevent lawsuit and other complaints from the patient, explain well the procedure and other conditions that may happen if they still prefer spinal anesthesia.
IV. PREMEDICATIONS
A. GOAL OF PREMEDICATION
● Diminish anxiety → Ex: benzodiazepine (midazolam) ● Provide relief of preoperative pain or perioperative amnesia → Ex: opioids (fentanyl) ● Prophylaxis against postoperative nausea and vomiting → Ex: antiemetics, 5HT3 receptor antagonist or 5- hydroxytyptamine (ondansetron, granisetron) ● Prevention of allergic reactions → Ex: antihistamine ● Prevention of aspiration pneumonia → Ex: antacids ● Decreasing upper airway secretions → Ex: anticholinergics (atropine) ● Today, preoperative sedative-hypnotics or opioids are almost never administered except for: → Intubated patients who have been previously sedated in the intensive care unit → Children 2-10 years old who will experience separation anxiety may benefit from this
→ Patients who are quite anxious despite preoperative interview
B. FACTORS TO BE CONSIDERED
● Clinical effects of medications → Ex: Benzodiazepine relieve anxiety and provide amnesia however they have no analgesic activity. On the other hand, opioids like fentanyl, hydromorphone and morphine could be used to alleviate pain due to its analgesic effects → Opioids can decrease discomfort for patients being transported to the operating room and during positioning in the operating table. However, opioids also cause respiratory depression, orthostatic hypotension and nausea and vomiting ● Health and emotional status of the patient ● Proposed surgical procedure ● Anesthetic plan ● Duration of surgical procedure → Long-acting agents should not be used for short surgical procedure and for ambulatory patients
C. PREMEDICATION FOR OPEN APPENDECTOMY
● IV fluids in order to correct dehydration that commonly develops as a result of fever and vomiting in patients with appendicitis. ● Patient started on antibiotics like; → Cefoxitin 1-2 g IV → cefotetan 1-2 g IV → cefazolin 1-2 g IV + metronidazole 0.5 g IV ● Fentanyl - For painful procedure like regional block or central venous line that will be performed while the patient is still awake ● IV midazolam 0.07 mg/kg → short-acting benzodiazepine that has the benefit of providing anterograde amnesia and reduce anxiety → administration of midazolam before operation is effective in decreasing the frequency of nausea and vomiting → binds to the GABA receptors which increases the frequency of opening of the associated chloride ion channel. → half-life is 2 hours and is the shortest among the benzodiazepine group because of its increased hepatic extraction ratio. → kidney failure may lead to prolonged sedation in patients receiving larger doses of midazolam due to the accumulation of a conjugated metabolite (α-hydroxymidazolam) ● Ondansetron, Granisetron → 5-HT3 receptor antagonist-type antiemetic ● Ramosetron → higher potency and longer antiemetic action than other 1st generation 5-HT3 antagonists such as ondansetron ● Clonidine and Dexamethasone can be use as premedication to prevent nausea and vomiting
Remember: ● Not all patients require preoperative medication because preoperative anxiety do not harm most patients ● Duration should be noted because effects of some sedatives may extend into the postoperative period and prolong recovery time ● Preoperative visit from an anesthesiologist resulted in a greater reduction in patient anxiety than preoperative sedative drugs ● Premedication should be given purposefully , not as a mindless routine
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Local anesthetic is injected into the epidural space. The same local anesthetic concentration is achieved within nerve roots only with much larger volumes and quantities of local anesthetic molecules during epidural and caudal anesthesia. Level of injection site for epidural anesthesia must generally be close to the nerve roots that must be anesthetized. Blockade of neural transmission in: Posterior nerve root fibers interrupts somatic and visceral sensation Anterior nerve root fibers prevents efferent motor and autonomic outflow Local anesthetics may also have actions on structures within the spinal cord during epidural and spinal anesthesia.
1. SOMATIC BLOCKADE
Neuraxial blocks can provide excellent operating conditions by: Interrupting the afferent transmission of painful stimuli and efferent impulses responsible for skeletal muscle tone. Sensory blockade interrupts both somatic and visceral painful stimuli. Effect of local anesthetics on nerve fibers varies according to: size, length and characteristics of the nerve fiber type and concentration of the local anesthetic Spinal nerve roots contain varying mixtures of these fiber types. Smaller and myelinated fibers are generally more easily blocked than larger and unmyelinated ones. Differential Blockade Clinical phenomenon that nerve fibers with different functions have different sensitivities to local anesthetic blockade. Explained by: size and character of the fiber types the fact that the concentration of local anesthetic decreases with increasing distance from the level of injection Sympathetic nerve fibers are blocked by the lowest concentration of local anesthetic followed by sensory nerve fibers responsible for pain and touch and finally motor nerve fibers. This relative sensitivity of certain nerve fibers is displayed by a spatial separation (sympathetic block will be approximately 2-4 dermatomes beyond motor block, the pain/touch will be 2-3 dermatomes beyond motor block). Presumed etiology is as the local anesthetic gets further from the injection site, it is present in lower concentration and sympathetic nerve fibers do not require the same concentration to be blocked as do motor nerve fibers.
2. AUTONOMIC BLOCKADE
Sympathetic Blockade Produced by interruption of efferent autonomic transmission at the spinal nerve roots during neuraxial blocks. 2 outflows from the spinal cord: Sympathetic outflow “Thoracolumbar” Sympathetic preganglionic nerve fibers (small, myelinated B fibers) exit the spinal cord with the spinal nerves from T1–L2 and may course many levels up or down the sympathetic chain before synapsing with a postganglionic cell in a sympathetic ganglion. Parasympathetic outflow
“Craniosacral” Parasympathetic preganglionic fibers exit the spinal cord with the cranial and sacral nerves. Neuraxial anesthesia DOES NOT block the vagus nerve. Physiological responses of neuraxial blockade result from decreased sympathetic tone and/or unopposed parasympathetic tone.
3. SYSTEMIC MANIFESTATIONS
Cardiovascular Manifestations
Neuraxial blocks produce variable decreases in blood pressure that may be accompanied by a decrease in heart rate. These effects are proportional to the dermatomal level and extent of sympathectomy. Vasomotor tone Primarily determined by sympathetic fibers arising from T5- L1, innervating arterial and venous smooth muscle. Blocking these nerves causes: Vasodilation of the venous capacitance vessels Pooling of blood in the viscera and lower extremities Decreasing the effective circulating blood volume and venous return to the heart. Arterial vasodilation may also decrease systemic vascular resistance. Effects may be minimized by compensatory vasoconstriction above the level of the block, particularly when the extent of sensory anesthesia is limited to the lower thoracic dermatomes. In a high sympathetic block : Does not only prevents compensatory vasoconstriction, Also blocks the sympathetic cardiac accelerator fibers that arise at T1–T4. Profound hypotension may result from: arterial dilation and venous pooling combined with bradycardia possibly milder degrees of decreased contractility Effects are exaggerated if venous pooling is further augmented by a head-up position or the weight of a gravid uterus. Unopposed vagal tone may explain the sudden cardiac arrest sometimes seen with spinal anesthesia. Deleterious cardiovascular effects should be anticipated and steps undertaken to minimize the degree of hypotension. Volume loading with 10 – 20 mL/kg of intravenous fluid in a healthy patient before initiation of the block has been shown repeatedly to fail to prevent hypotension. Left uterine displacement in the third trimester of pregnancy helps to minimize physical obstruction to venous return. (AORTOCAVAL SYNDROME) Despite these efforts, hypotension may still occur and should be treated promptly. Autotransfusion may be accomplished by placing the patient in a head-down position A bolus of intravenous fluid (5–10 mL/kg) May be helpful in patients who have adequate cardiac and renal function to be able to “handle” the fluid load after the block wears off. In cases of excessive or symptomatic bradycardia, treatment is done by giving Atropine
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In cases of hypotension, treatment is done by giving vasopressors Direct alpha-adrenergic agonists (e.g. phenylephrine) produce arteriolar constriction and increase reflexive bradycardia increased systemic vascular resistance
Ephedrine
“mixed” agent because it has both direct and indirect beta- adrenergic effects Increases heart rate and contractility Produces vasoconstriction Epinephrine 2 mcg boluses were found to be effective in treating anesthesia-induced hypotension However, if there is profound hypotension and/or bradycardia persists, vasopressor infusions are used
Pulmonary Manifestations
Pulmonary physiology is minimally altered by neuraxial blocks since the diaphragm (primary muscle of respiration) is innervated by the phrenic nerve, which has fibers that originate from C3 to C5 (that’s too high to be affected!) Even with high thoracic levels, tidal volume is unchanged Only a small decrease in vital capacity (due to loss of abdominal muscles’ contribution to forced expiration) High level of neural blocked may impair the accessory muscles of respiration (i.e. intercostals and abdominal muscles) COPD patients that rely on these muscles may have difficulty in actively inspiring and expiring Patients with limited respiratory reserve may have trouble coughing and clearing secretions For surgical procedures above the umbilicus, pure regional technique may not be the best choice if the patient has severe lung disease However, the patient can still benefit from the effects of thoracic epidural analgesia (with dilute local anesthetics and opioids) during the post-operative period, particularly after upper abdominal or thoracic surgery There is evidence that suggests postoperative thoracic epidural analgesia in high-risk patients can improve pulmonary outcome by decreasing the incidence of pneumonia and respiratory failure, improving oxygenation, and decreasing the duration of mechanical ventilatory support.
Gastrointestinal Manifestations
Neuraxial block-induced sympathectomy allows vagal tone dominance small, contracted gut with active peristalsis Since sympathetic outflow originates at the T5-L1 level Improves operative conditions during laparoscopy when used as an adjunct to general anesthesia Postoperative epidural analgesia with local anesthetics and minimal systemic opioids speeds up the return of GI function after abdominal procedures Hepatic blood flow decreases in any anesthetic procedure (including neuraxial anesthesia), with reductions in mean arterial pressure Anesthesia affects the splanchnic and hepatic circulation in various directions and different degrees. The majority of
anesthetics decreases portal blood flow in association with a decrease in cardiac output. However, hepatic arterial blood flow can be preserved, increased, or decreased, depending on the effect of the particular drug. Most of the time, it is decreased, but in cases where it is increased, it is usually not enough to compensate for the decrease in portal blood flow. Therefore, total hepatic blood flow is usually decreased during anesthesia
Urinary Tract Manifestations
Neuraxial anesthesia has little effect on renal function Because renal blood flow is strictly maintained through autoregulation Neuraxial anesthesia at the lumbar and sacral levels blocks both sympathetic and parasympathetic control of bladder function loss of autonomic bladder control urinary retention (at least until the block wears off) If no urinary catheter was placed on the patient preoperatively , a regional anesthetic with the shortest duration still sufficient for the procedure should be used , and minimal safe volume of IV fluid should be administered Patients with urinary retention should be checked for bladder distention
Metabolic and Endocrine Manifestations
Surgical trauma may produce a systemic neuroendocrine response through the activation of somatic and visceral afferent nerve fibers + localized inflammatory response This includes: Increased ACTH Increased cortisol Increased epinephrine Increased norepinephrine Increased vasopressin Activation of RAAS These manifest clinically as: Intraoperative and postoperative hypertension Tachycardia Hyperglycemia Protein catabolism Suppressed immune responses Altered renal function Neuraxial block can partially suppress (during major invasive surgeries) or totally block (during lower extremity surgeries) this neuroendocrine stress response To maximize the effect of this blunting of the stress response, the block should precede incision and should continue into the postoperative period
C. CLINICAL CONSIDERATIONS
Neuraxial blockade may be used alone or in conjunction with general anesthesia for most procedures below the neck , including: Lower abdominal Inguinal Urogenital Rectal Lower extremities
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1. EQUIPMENT
Since the performance of neuraxial procedures is under aseptic technique, the clinician is expected to maintain a sterile environment. Cap, masks, handwash, sterile gloves are required.
Spinal Needle
Commercially available in an array of sizes, lengths, bevel and tip designs. Spinal needles generally used today are 22 to 27 G, but sizes ranging from 19 to 30 G are available. (Doc So: They usually use 26G needle). All should have a tightly fitting removable stylet that completely occludes the lumen to avoid tracking epithelial cells into the subarachnoid space
Can be divided into either sharp (cutting)-tipped or blunt- tipped needles. Quincke needle is a cutting needle with end injection. The introduction of blunt tip (pencil-point) needles has markedly decreased the incidence of postdural puncture headache. Whitacre needle and other pencil-point needles have rounded points and side injection. The Sprotte needle is a side-injection needle with a long opening. It has the advantage of more vigorous CSF flow compared with similar gauge needles. However, this can lead to a failed block if the distal part of the opening is subarachnoid (with free flow CSF), the proximal part is not past the dura, and the full dose of medication is not delivered. In general, the smaller the gauge needle, the lower the incidence of headache. ( Doc So : Size of the needle does not have any effect. Pahihirapan mo lang sarili mo pag masyado maliit) ( Doc So : Usually they use cutting-type needles (Quincke) since mahirap ipasok yung blunt needles kasi mapurol).
Figure 4. Spinal Needles
Spinal Catheter
Rarely used for spinal anesthesia since the procedure is only “one-shot”. Very small subarachnoid catheters are currently no longer approved by the US Food and Drug Administration. The withdrawal of these catheters was prompted by their association with cauda equina syndrome (CES). Larger catheters designed for epidural use are associated with relatively high complication rates when placed subarachnoid; however, they are frequently used for continuous spinal
anesthesia following accidental dural puncture during performance of epidural anesthesia. Mostly the catheter size used are 18G and 20G.
2. TECHNIQUE
The procedure is usually carried out with the patient in the sitting or lateral decubitus position. The goal of positioning is to help establish a straight path for needle insertion between the spinal vertebrae. The most commonly used position is the sitting position. This is because, in the lateral decubitus position, the spinal anatomy is usually not laterally symmetrical as it is in the sitting position.
Figure 5. Patient Position A line drawn between the highest points of both iliac crests ( Tuffier’s line ) usually crosses either the body of L4 or the L4–L5 interspace. Counting spinous processes up or down from these reference points identifies other spinal levels.
Figure 6. Tuffier’s Line
After the patient is in proper position, the access site is identified by palpation.
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This is usually very difficult to achieve with obese patients because of the amount of subcutaneous fat between the skin and spinous process. The space between 2 palpable spinous processes is usually the site of entry. Local anesthetic (usually 1% lidocaine) is used for skin infiltration, and a wheal is created at the site of access chosen, either midline or paramedian.
Two Approaches for Spinal Anesthesia
Median Approach The spinal approach to the intrathecal space is midline with a straight line shot. The spinal needle is introduced into the skin, angled slightly cephalad. The needle is advanced from skin through the deeper structures until two “pops” are felt. The first is penetration of the ligamentum flavum, and the second is penetration of the dura–arachnoid membrane. Successful dural puncture is confirmed by withdrawing the stylet to verify free flow of CSF.
Paramedian Approach The paramedian technique may be selected if subarachnoid block is difficult, particularly in patients who cannot be positioned easily (eg, severe arthritis, kyphoscoliosis, or prior spine surgery) The skin wheal from the local anesthetic is placed about 2 cm from midline, and the spinal needle advances at an angle toward the midline. In this approach, the supraspinous and interspinous ligaments are usually not encountered. Hence, there is little resistance encountered until reaching the ligamentum flavum.
Figure 7. Median and Paramedian Approach
3. FACTORS AFFECTING LEVEL OF SPINAL BLOCK
Figure 7. Factors affecting the level of Spinal anesthesia (Butterworth et al., 2015) The most important that affect the level of spinal anesthesia are: Baricity, Position of the Patient and Drug Dosage In general, the larger the dose and the more cephalad the level of injection, the more cephalad the level of block that will be obtained.
Baricity of Anesthetic Solution
Baricity refers to the degree of specific gravity of the anesthetic solution relative to specific gravity of CSF. The specific gravity of CSF is 1.003 – 1.008. An anesthetic solution with a specific gravity GREATER than CSF is HYPERBARIC An anesthetic solution with a specific gravity LESSER than CSF is HYPOBARIC An anesthetic solution with a specific gravity EQUAL to CSF is ISOBARIC Mixing certain compounds and solutions to the anesthetic can increase or decrease its baricity, allowing a degree of control on the level of block. Addition of sugars such as glucose and dextrose INCREASE BARICITY , thus more HYPERBARIC Addition of sterile water and fentanyl make DECREASE BARICITY , thus more HYPOBARIC Addition of CSF makes anesthetic solutions ISOBARIC A more hyperbaric solution would settle at the most dependent areas of the spine. In a person with a normal spine anatomy this would be located at the level of T4 – T
Figure 8. Image highlighting the T4-T8 areas as the most dependent area of a normal spine. Hyperbaric solutions would tend to settle towards those areas (Butterworth et al., 2015)
NTK: What happens to the level of block if CSF increases in viscosity? Theoretically, a more viscous CSF means an increased specific gravity
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E. EPIDURAL ANESTHESIA
A type of neuraxial anesthesia wherein the local anesthetic (LA) is injected into the epidural space to anesthetize the spinal nerve roots that traverse the space Epidural space : surrounds the dura mater circumferentially and extends from the foramen magnum to the sacrococcygeal ligament; contains adipose tissue, blood vessels, nerve roots, loose connective tissue Boundaries : Posteriorly Ligamentum flavum Laterally Pedicles, Intervertebral foramina Anteriorly Posterior longitudinal ligament
Offers a range of applications wider than the typical all-or- nothing, single dose spinal anesthetics Widely utilized for surgical anesthesia, obstetric analgesia, post- operative pain control, and chronic pain management. It is used for anesthesia of abdominal, pelvic, and lower extremity procedures and, less commonly, thoracic procedures May also be used to supplement general anesthesia for thoracic, abdominal, and pelvic procedures and for postoperative analgesia following these procedures
Segmental Block
Characterized by a well-defined band of anesthesia at certain nerve roots , leaving the nerve roots above and below unblocked Can be made possible because the anesthetic can be confined close to the level at which it was injected Usually used in labor and postoperative analgesia
1. EQUIPMENT
Epidural Needle
Standard epidural needle is usually 17-18 gauge, 3 or 3. inches long , and has a blunt bevel with a gentle curve of 15- 30° at the tip
TUOHY NEEDLE Usually used Blunt, curved tip theoretically helps to push away the dura after passing through the ligamentum flavum instead of penetrating it Other modifications to needles used in epidural anesthesia are winged tips and introducer devices set into the hub designed for guiding catheter placement.
CRAWFORD NEEDLE Straight without a curved tip May have a greater incidence of dural puncture but facilitate the passage of an epidural catheter.
Figure 9. Epidural Needles. Types of epidural needle (left), Tuohy needle (right)
Epidural Catheter
Utilized when continuous infusion or intermittent bolus techniques are employed
19- or 20-gauge catheter is introduced through a 17- or 18- gauge epidural needle May be taped on the skin or tunneled under the skin (for prolonged use of > 1 week)
Figure 10. Epidural Catheter
2. TECHNIQUE
An epidural block can be performed at the lumbar, thoracic, or cervical level Can be used as a single shot techniques or with a catheter that allows intermittent boluses and/or continuous infusion as indicated Epidural space can be accessed using the midline or the paramedian approach Epidural needle is passed through the skin and the ligamentum flavum, with the needle stopping short of piercing the dura To identify the potential (epidural) space, two techniques can be used: (1) Loss of Resistance Technique, (2) Hanging Drop Technique
Loss of Resistance Technique
The needle is advanced through the subcutaneous tissues with the stylet in place until the interspinous ligament is entered ⇨ indicated by an increase in tissue resistance Stylet or introducer is removed and a glass syringe filled with approximately 2.0 mL of saline or air is attached to the hub of the needle A resistance is felt if the tip of the needle is within the ligament and thus, injection is not possible. With a slow advancement of the needle, a sudden loss of resistance and thus easier injection ⇨ needle is in the epidural space
Figure 11. Loss of Resistance Technique
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Notes from Doc So: Loss of Resistenance Technique:
1. Use of air Don’t inject too much air because it may cause a post-dural headache-like headache (BUT no diplopia, tinnitus, not relieved by lying down) Pain due to air accumulating at foramen magnum 2. Use of saline – preferred and more recommended
Hanging Drop Technique
Requires that the hub of the needle be filled with solution so that a drop hangs from its outside opening once the interspinous ligament has been entered and the stylet has been removed As the tip of the needle enters the epidural space, the drop of fluid is sucked into the needle due to the negative pressure created Artificial negative pressure is created in the epidural space when the epidural needle comes in contact with the dura mater and pushes it away ⇨ increase in epidural space volume Increase in epidural space volume ⇨ decrease in pressure ⇨ atmospheric air rushes in to fill the void, carrying with it the hanging drop
Figure 12. Hanging Drop Technique
3. ACTIVATION OF EPIDURAL ANESTHESIA
Since the quantity of local anesthetic used in epidural anesthesia is larger than that needed for spinal anesthesia, toxic side effects are likely if a full epidural dose is injected intrathecally or intravascularly Once you gain entrance to the epidural space, gently aspirate for blood or CSF. Presence of these are good indicators of needle position, but their absence is not foolproof of whether needle tip is subarachnoid or intravenous To avoid adverse effects of wrong needle placement and administration, test dosing and incremental dosing may be done
Test Dose
Can detect both subarachnoid and intravascular injection Classic test dose : combination of a local anesthetic and epinephrine [i.e. 3.0 mL of 1.5% lidocaine with 1:200, epinephrine (0.005 mg/mL)]
Incremental Dose
Once aspiration is negative, a fraction of the total intended local anesthetic is injected (usually 5.0 mL) Dose should be large enough for mild symptoms of intravascular injection to occur, but small enough to avoid seizure or cardiovascular compromise Local Anesthetic Toxicity ⇨ Rescue lipid emulsion (20% Intralipid 1.5 mL/kg)
4. FACTORS AFFECTING THE DEGREE AND LEVEL
OF BLOCKADE
Epidural blockade is most effective when the block or the catheter is inserted in a location that corresponds to the dermatomes covered by the surgical incision The most rapid onset and the densest block occur at the site of injection
By inserting the catheter closer to the dermatomal distribution of the surgical site, a lower dose of drug can be given, thereby reducing side effects
Generally accepted guideline for administration of epidural anesthetic (adults): 1 - 2 mL of local anesthetic per segment to be blocked
E.g. To achieve a T4 sensory level from and L4-L5 injection ( segments) would require about 12-24 mL of local anesthetic
Dose, Volume, Concentration
DOSE of Local Anesthetic ⇨ concentration of the solution and the volume injected CONCENTRATION of the drug affects the density of the block Higher concentration = more profound motor and sensory block DEGREE OF SPREAD OF BLOCK ⇨ affected by the volume and total anesthetic dose A larger volume of the same concentration of LA will block a greater number of segments However, if the total dose of LA is unchanged but the concentration is doubled, the volume can be halved to achieve similar spread of LA
Patient Positioning
Trendelenburg, and reverse Trendelenburg positions can be used to help blockade in desired dermatomes Trendelenburg position increases the spread and accelerates the onset of epidural anesthesia for Cesarean section
Patient Characteristics: Age, Height, Weight
Age Dose required to achieve the same level of anesthesia decreases with age ⇨ age-related decreases in the size and compliance of the epidural space Height Patient height affects the extent of cephalad spread Shorter people may require a lesser amount of LA than taller people Weight In morbidly obese patients, there may be compression of the epidural space related to increased intra-abdominal pressure ⇨ a higher block may be attained with a given dose of LA
Additives
Greater effect on the quality of epidural anesthesia than the duration of the block Epinephrine in concentrations of 5.0 mcg/mL can prolong the effect of epidural lidocaine, mepivacaine, levobupivacaine, etidocaine, or ropivacaine Also delays vascular absorption and reduces peak systemic blood levels
5. EPIDURAL ANESTHETIC AGENTS
Considerations to which epidural agent is most appropriate are: desired clinical effect, use (i.e. as primary anesthetic, supplementation of general anesthesia, or analgesia), and anticipated duration of the procedure Following the initial general standard of 1-2 mL per segment bolus, repeat doses delivered through an epidural catheter may be done on a fixed time interval or when the block demonstrates some degree of regression One-third to one-half of the initial activation dose can be reinjected in incremental doses once some regression in the sensory level has occurred
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Length of surgical procedure Patient Position during surgical procedure Coexisting disease Anesthesiologist Skill See appendix for the BRCA of the procedures and anesthesia taken into consideration To summarize: Regional anesthesia will be used - specifically spinal anesthesia technique or subarachnoid spinal block Using Bupivacaine, an amide agent. To be more exact, the preparation of bupivacaine is 0.75% in 8.25% dextrose. Since the appendix is in the lower abdomen, the dose (mg) needed is10- The duration of anesthesia will be 90-120 min without epinephrine while 100-150 min with epinephrine.
VIII. INTRAOPERATIVE PERIOD
A. PATIENT POSITIONING
Proper patient positioning has been shown to be an independent predictor for a fast and successful administration of anesthesia and overall surgery. A joint responsibility of both surgeon and anesthesiologist Basic Surgical Positions include: Supine Lateral Prone Lithotomy Variations in Basic Surgical Positions Trendelenburg Reverse Trendelenburg Fowler’s/Semi Fowler Beach Chair Position Wattson Jone Position Lateral decubitus Jackknife Position Position for Robotic Surgery Important things to assess preoperatively: length of procedure surgeon’s preference of position required position for procedure anesthesia to be administered patient's risk factors (age, weight, skin condition, mobility/ limitations, pre-existing conditions, airway, etc.) patient’s privacy and medical needs An appropriate position: does not interfere with respiration and circulation no pressure on peripheral nerves minimal skin pressure accessibility to surgical or operative sites accessibility for anesthetic administration no undue musculoskeletal discomfort
B. PATIENT POSITIONING IN SPINAL ANESTHESIA
IN OPEN APPENDECTOMY
Spinal anesthesia requires access to the spine thus the three main positions for administering anesthesia are : lateral decubitus, sitting position, and prone/Buie’s/Jackknife For Spinal Anesthesia in Open Appendectomy, the procedure is usually carried out with patient sitting or in lateral decubitus
Lateral Decubitus
Doc So: It is the most commonly used position in the administration of spinal anesthesia The back of the patient should be parallel to the edge of the bed closest to the anesthesiologist, with their knees flexed and pulled high against the abdomen or chest and neck flexed (fetal position)
Figure 16. Lateral Decubitus
Sitting
Sitting position is best used for lumbar and sacral anesthesia , obese patients, or when there is difficulty in finding the midline In practice, many anesthesiologists prefer the sitting position in all patients who can be positioned this way because it avoids the potential rotation of the spine that can occur with the lateral decubitus position. Most commonly used and most preferred position by surgeons and anesthesiologist for this procedure (open appendectomy) Patient sits with their elbows resting on their thighs or a bedside table, or they can hug a pillow while flexing their spine (arching the back “like a mad cat”) to maximize the “target” area between adjacent spinous processes and bring the spine closer to the skin surface Doc So : the patient sits at the edge of the bed, holds a pillow to their abdomen, bring their body towards their thighs, and feet resting in the stool = comfortable for patients with appendicitis
Figure 17. Sitting
C. FLUID MANAGEMENT
Intraoperative Fluid therapy Supplying basic fluid requirements Replacing residual preoperative and intraoperative loses Blood loss Fluid redistribution Evaporation Determinants of the type of solution for replacement therapy: Surgical procedure Expected blood loss Minor procedures: Dilute maintenance solutions
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All other procedures: Lactated Ringer’s, Plasmalyte
1. GOALS OF FLUID THERAPY
Restoration and maintenance of effective circulating blood volume Assures correct fluid balance, avoiding both dehydration and fluid overload Assures sufficient circulation, and therefore adequate oxygen Delivery to organs, avoiding both hypo- and hyperperfusion The induction of anesthesia, and surgical trauma often cause decrease in effective circulating volume, and fluid therapy is considered as first line of treatment to achieve hemodynamic Maintenance of correct plasma components
Prevents inappropriate movement across the cellular membrane
2. INTRAVENOUS FLUIDS
Characteristics of an ideal resuscitation fluid: Produces a predictable and sustainable increase in eintravascular volume Has a chemical composition as close as possible to that of extracellular fluid Metabolized and completely excreted without accumulation in tissues No adverse metabolic or systemic effects Is cost effective in terms of improving patient outcome
3. TYPE OF INTRAVENOUS FLUIDS
Crystalloids
Include electrolyte solutions with or without a bicarbonate precursor such as acetate or lactate Isotonic, hypotonic, or hypertonic with respect to plasma Used to replace extracellular fluid losses from perspiration, respiration, and urine output. Increases the vascular volume. E.g. normal saline solution, lactated ringer’s
Colloids
Contains a complex sugar or protein suspended in an electrolyte solution. Increases vascular volume, preload, cardiac output, and tissue perfusion in volume responsive patients For patients with severe intravascular fluid deficits: hemorrhagic shock, burns e.g. Human albumin, Fresh frozen plasma
Normal Saline Solution
Contains no electrolytes other than sodium and chloride. Most commonly used solution For correction of fluid deficits and imbalances such as hyponatremia, hypochloremia, and metabolic alkalosis. Excessive volume administration is associated with hyperchloremic acidosis
Lactated Ringer’s Solution
A balanced salt-based fluid, contain other electrolytes, with or without a bicarbonate precursor. Its average pH is 6.5, a hypo-osmolar solution, and contains similar electrolytes as plasma. Usually more physiologically compatible to plasma than normal saline.
4. CHOOSING THE RIGHT FLUID
The choice between crystalloids and colloids to optimize the circulating blood volume remains unclear. Colloids: patients undergoing major abdominal surgery. Have the advantage in maintaining intravascular osmotic pressure when using lesser volumes to achieve the same hemodynamic endpoints Is associated with less fluid accumulation and fewer postoperative complications Crystalloids: patients undergoing minimally/moderately invasive surgery Balanced electrolyte crystalloid solution for routine perioperative fluid administration Administered on a 1.5:1.0 volume basis until a transfusion threshold is met Avoid dextrose-containing solutions - > could lead to hyperglycemia A smaller fluid volume is appropriate in patients with a history of heart failure or chronic obstructive pulmonary disease.
Table 2. Comparison between crystalloids and colloids Crystalloid Colloid Half-life of 30-60 minutes Half-life of several hours or days 3x the volume needed for replacement
Volume for volume replacement Excessive use causes peripheral and pulmonary edema
Excessive use can precipitate cardiac failure
Molecules are small enough to freely cross capillary walls, so fluid remains in the intravascular walls
Molecules too large to cross capillary walls, so fluid remains in intravascular spaces for longer Inexpensive Expensive Non-allergenic Risk of anaphylaxis
5. REPLACING BLOOD LOSS
In order to maintain intravascular volume, blood loss should be replaced with a crystalloid or colloid solution. Further blood loss is replaced with red blood cell transfusions to maintain the hemoglobin or hematocrit at a normal level.
6. COMPLICATIONS OF FLUID THERAPY
Fluid therapy can cause deficient or excessive circulating blood volume Other complications: Hemodynamic instability and tissue hypoperfusion Dilution of platelets and coagulation factors leading to dilutional coagulopathy Electrolyte imbalances Infection Phlebitis Extravasation
7. INTRAOPERATIVE FLUID STATUS MONITORING
It is important to monitor the patient’s fluid status during the surgery so that adequate fluid therapy is given to maintain the hemodynamic stability. Parameters: Urine output, blood pressure, and pulse rate. Other things that can be used to assess the blood and fluid loss: The amount of suction from the surgical site
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Drug Toxicity
Table 4. Local anesthetics and their rank order in terms of potency and cardiotoxicity LOW potency; RAPIDLY metabolized
INTERMEDIATE
potency and toxicity
HIGH potency and toxicity
Cloroprocaine Lidocaine Mepivacaine
Levobupivacaine Ropivacaine Bupivacaine Tetracaine
IX. POST OPERATIVE ASSESSMENT
Pain remains a significant concern for patients and represents an extremely negative experience for patients undergoing surgery. Many patients experience pain in the postoperative period despite the use of potent techniques such as patient-controlled analgesia, epidural analgesia, and regional anesthesia. The American Pain Society has advocated the assessment of pain as the fifth vital sign This approach may improve the efficacy of pain treatment.
A. PAIN MANAGEMENT
Multimodal Analgesia
Multimodal analgesia is a combination of different classes of medications , having different (multimodal) pharmacological mechanisms of action and additive or synergistic effects It has at least two desirable effects. may decrease the use of opioids and associated side effects (e.g., delirium, and respiratory depression), tolerance, and diversion. may be a more effective pain control strategy, potentially decreasing the complications associated with suboptimal pain control, such as pneumonia, deep venous thrombosis, and postoperative cognitive dysfunction.
Drugs for Multimodal Analgesia
Opioids , the staple of postoperative pain management, reduce pain by acting on the m-receptor. Analgesia is accompanied by unwanted side effects such as sedation, nausea and vomiting, constipation, respiratory depression which are promulgated by the m-receptor. With this, physicians are abandoning the old opioid-centric model and focusing more on multimodal approach to postoperative pain relief. MORPHINE, OXYCODONE, HYDROMORPHONE Morphine Strong receptor agonist that is useful in treating severe pain. Often used adjunct in anesthesia Risks: Respiratory depression, severe constipation, addiction liability, convulsions Cost-effective than Oxycodone and Hydromorphone Adjunct Drugs Ibuprofen In addition to systemic opioids, diminishes postoperative pain intensity, reduces the opioid requirement by approximately 30%, decreases opioid-related side effects Paracetamol
Analgesic effect is 20–30% less than that of NSAIDs, but its pharmacological profile is safer Opioid sparing effects when IV Either NSAIDs or acetaminophen , or both can be used together with morphine to reduce the unwanted effects of uncontrolled pain and accidental overdoses of opioids. Analgesic efficacy of acetaminophen improves when the drug is administered together with NSAIDs, and it significantly reduces pain intensity and spares opioid consumption after an abdominal surgery.
Transversus Abdominal Pain (TAP) Block
Truncal regional analgesia that results in analgesia to the anterior abdominal wall. Pain secondary to any transgression of the abdominal wall can be attenuated by a TAP block, including appendectomy. It is also used for postoperative analgesia for procedures below the umbilicus. Injection of local anesthetic into this plane under ultrasound guidance results in pain relief for 8 to 12 hours.
B. MONITORING AND LABORATORY TESTS
Postoperative Monitoring
Standard protocol for any procedure Check the patient’s ABC (airway patency, breathing, circulation) before wheeling into the PACU Endorsement of pertinent information Site and type of local block Drug Dosage Time of administration Anticipated duration of action Standards for a Safe Practice of Anesthesia (WHO-WFSA) Clinical observation of tissue oxygenation and perfusion Monitoring of respiratory rate and pulse rate Consistent use of pulse oximetry Intermittent non-invasive monitoring of blood pressure Assessment of pain using age-appropriate scale Temperature monitoring Urine output monitoring by bladder catheterization Necessary in patients who have had spinal or epidural anesthesia for longer than four hours Look out for signs of Airway obstruction Hypoxia Hemorrhage Hypotension Hypertension
Pain Shivering Hypothermia Vomiting
Routine Laboratory Tests
Hemoglobin Hematocrit Serum and urine sodium, potassium, and creatine
Regional Anesthesia
Periodically record sensory and motor level to document any regression of the block Monitor Postoperative dynamic pain scores Sedation
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Dermatomal distribution Motor blockade All PACU staff should also be trained to recognize and manage local anesthetic systemic toxicity (LAST) It occurs in 0.03%, or 0.27 episodes per 1,000 cases using peripheral nerve blocks Common in pain management postoperatively First presenting symptom of neuraxial injury (American Society of Regional Anesthesia) Weakness that is stronger than expected Can recur after initial resolution Progress or appear in the part of the body inconsistent to the block
X. POST OPERATIVE COMPLICATIONS AND
ADVERSE DRUG REACTIONS
Post-operative complications and adverse drug effects vary in each patient. In general, the most common cause of morbidity and mortality are the respiratory and circulatory complications. Other more specific complications that a patient may experience in the case includes: hypotension , bradycardia -- due to sympathetic blockade; difficulty breathing, hemodynamic and respiratory arrest that may or may not lead to hypoxemia breathing numbness or weakness of upper extremities - high blockade; cardiac arrest ; urinary retention; horner’s syndrome ; other drug toxicity , backache postdural puncture headache , conus medullaris injury, post-operative neurological complication, multiple sclerosis, spinal or epidural hematoma, meningitis and epidural abscess.
A. Respiratory Complications
Dyspnea and Hypoventilation
Difficulty of breathing may be associated as an adverse effect of the residual anesthetic drugs on respiratory drive in PACU patients. One of the most potent drugs that can cause dyspnea to the patient is Opioid which is commonly given to the patients for pain management. This complication may also be associated with hypoventilation (PaCO2 >45 mm Hg) and can also be secondary to thoracic or cervical spread of drug in spinal anesthesia. This may also be due to proprioceptive blockade of afferent fibers from abdominal and chest wall muscles and splinting due to incisional pain. In most instances, the hypoventilation is mild, and most cases are undiagnosed Significant hypoventilation is usually clinically apparent when the PaCO2 is >60 mm Hg or arterial blood pH is <7. Signs are varied and include excessive somnolence, airway obstruction, slow respiratory rate, tachypnea with shallow breathing, or labored breathing. Mild to moderate respiratory acidosis may cause tachycardia, hypertension, and cardiac irritability via sympathetic stimulation, but more severe acidosis produces circulatory depression.
If significant hypoventilation is suspected, assessment and management is facilitated by capnography and/or arterial blood gas measurement. Treatment should generally be directed at the underlying cause, but marked hypoventilation always requires assisted or controlled ventilation until causal factors are identified and corrected. Obtundation, circulatory depression, and severe acidosis (arterial blood pH <7.15) are indications for immediate and aggressive respiratory and hemodynamic intervention, including airway and inotropic support as needed. Antagonism of opioid-induced depression with large doses of naloxone often results in sudden pain and marked increase in sympathetic tone. Naloxone, however, can cause hypertensive crisis, pulmonary edema, and myocardial ischemia or infarction. If naloxone is used to reverse opioid induced respiratory depression, titration in small increments (80 mcg in adults) usually avoids complications by reversal of hypoventilation without significant reversal of analgesia.
Hypoxemia
Mild hypoxemia is associated with hypoventilation and commonly seen in patients recovering from anesthesia when supplemental oxygen is not given. Mild to moderate hypoxemia , defined as PaO 250–60 mmHg , in young healthy patients may be well tolerated initially. However, may cause progressive acidosis and circulatory depression upon increasing duration or severity. Common sign of cyanosis may also not be obvious or even absent if the hemoglobin concentration is reduced. Other signs that can be observed in hypoxemic patients are restlessness , tachycardia , or cardiac irritability (ventricular or atrial). Obtundation , bradycardia , hypotension , and cardiac arrest are late signs. Due to these, routine monitoring of pulse oximetry in the PACU was utilized to facilitate early detection leading to fewer adverse outcomes. Arterial blood gas measurements may also be performed to confirm the diagnosis and guide therapy. Oxygen therapy with or without positive airway pressure is the cornerstone of treatment for hypoxemia. Routine administration of 30% to 60% oxygen can be given to the patient to prevent hypoxemia even with moderate hypoventilation and hypercapnia. If the patient exhibits severe or persistent hypoxemia, 100% oxygen should be given via a nonrebreathing mask or endotracheal tube until the cause is established and other therapies are instituted; controlled or assisted mechanical ventilation may also be necessary. Bronchospasm should be treated with aerosolized bronchodilator therapy. Diuretics should be given for circulatory fluid overload and cardiac function should be optimized. Persistent hypoxemia, despite the use of 50% oxygen, is an indication for positive end-expiratory pressure ventilation or CPAP.
B. Cardiac Complications
Hypotension
Postoperative hypotension is most commonly due to hypovolemia.
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Paracetamol can also be given Patients can use abdomen binder Conservative treatment also involves drinking of caffeine
Notes from Doc So:
1. Abdomen binder can be used to put pressure and close the
breach in dura mater and stop the
2. Stopping the CSF leak cures the PDPH.
E. SPINAL HEMATOMA
Needle or catheter trauma : causes minor bleeding in the spinal canal Risk Factor: Presence of abnormal coagulation or a bleeding disorder Need for coagulation tests and history of bleeding of the px Compress neural tissue and causing direct pressure injury and ischemia. Symptoms: sharp back and leg pain with a motor weakness and/or sphincter dysfunction Onset of symptoms: more sudden than with epidural abscess. Management: Neurological imaging (magnetic resonance imaging [MRI] or computed tomography [CT]) and neurosurgical consultation. Surgical decompression within 8 – 12 hr improves the occurrence of neurological symptom after spinal hematoma.
F. TRANSIENT NEUROLOGIC SYMPTOMS (TNS)
Incidence: greatest among outpatients, males undergoing surgery in the lithotomy position, and least among inpatients undergoing surgery in positions other than lithotomy. Described as back pain radiating to the legs without sensory or motor deficits Origin of most neurological complications: Needle trauma and local anaesthetic neurotoxicity (Brull et al., 2007). Usually associated with nerve compression following infection, abscess or formation of hematomas. Evident after resolution of the spinal anesthetic and may last for 2 to 7 days.
Factors Associated with Transient Neurologic
Symptoms (TNS)
1. Mechanical trauma by needle
Long bevel/sharper needles : greater incidence but lesser
severity of injury
Short bevel: decreased incidence but potentially more
severe injuries.
2. Mechanical trauma due to intraneural injection
Low injection pressures : return to normal motor function
High injection pressure : persistent motor deficits.
3. Neurotoxicity: inhibition of rapid axonal transport and formation
of endoneurial edema is based on the potency of anesthetic used, concentration and duration of application.
G. MENINGITIS
Uncommon Presents as fever, headache, back pain and emesis
Appear within hours to days after administration of the anesthesia. Causes can either be exogenous or endogenous but can also be due to problems in aseptic technique.
H. CONUS MEDULLARIS INJURY
Direct injection into the spinal cord can cause paraplegia. Medullary cone damage may result in cauda equina syndrome with sensory deficits and bowel and bladder disorders. Cauda equina or spinal puncture are low if it is assumed a puncture below L3, thus an ultrasound guide would decrease this complication.
Notes from Doc So:
3. Unlikely to happen in the case because the spinal
anaesthesia is induced at the level of T4.
4. Cauda Equina also swims away from the needle the first time
you induce the anaesthesia.
5. Risks usually happen if you do it more than once.
I. POSTOPERATIVE NAUSEA AND VOMITING (PONV)
Most common complication in the immediate postoperative period Caused by hypotension or unopposed vagal stimulation. Treatment and Management: More effective if administered after induction than at the end of surgery. Serotonin receptor agonists Agents lack sedative effects which is advantageous in the postoperative period. Dexamethasone Direct antiemetic effect Can reduce postoperative pain and need for postoperative opioids. Contraindicated in glucose intolerant patients Other effective prophylactic agent for PONV: 1.5 mg transdermal scopolamine Aprepitant : Neurokinin-receptor antagonist
XI. DISCHARGE CRITERIA
Two phases of recovery Phase I Immediate intensive care level recovery that cares for patient during emergence and awakening from anesthesia and continues until standard PACU criteria are met transitioning them to Phase II, in-patient setting or to an intensive care setting for continued care Phase II Ensures that the patient is ready to go home
PHASE I
After surgery and before discharge from the Post Anesthesia Care Unit (PACU-Phase I), a postoperative note should be written by the anesthesiologist. Documents: Patient’s recovery from anesthesia Any apparent anesthesia related complications immediate postoperative condition of the patient
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Any measures undertaken to treat such complications Patient’s disposition if where to be discharge (ICU, In-patient or Out-patient)
Figure 19. Elements required by Center for Medicare and Mediaid Service in all postoperative notes
Observe for Respiratory depression for at least 20-30 minutes after the last dose of parental opioid Minimum criteria for px. recovering from general anesthesia (if used adjunct) Check for easy arousability Full orientation Ability to maintain and protect airway Stable vital signs for at least 15- 30 mins Ability to call help (if necessary) No obvious complication (such as active bleeding) Control postoperative pain, nausea and vomiting Reestablish Normothermia Apply the Postanesthetic Aldrete Recovery System (PAS) Ideally, the patient should be discharged when the total score of PAS is 10, but a minimum of 9 is required
Figure 20. Post anesthetic Aldrete recovery score
In addition to PAS, patients receiving regional anesthesia should also be assessed for regression of both sensory and motor blockade Avoids inadvert injuries due to motor weakness or sensory deficits Catch possible complications Ex: failure of a spinal or epidural block to resolve 6hr after the last dose of local anesthetic raises the possibility of spinal subdural or epidural hematoma, which should be excluded by prompt radiological imaging and neurologic evaluation. Apply the Bromage Scale Measure the motor block Important to assess: determine the amount of motor function prevent pressure areas ensure the patient is safe to ambulate (if allowed) detect the onset of complications (epidural hematoma or abscess) intensity of motor block is assessed by the patient's ability to move their lower extremities flex the knees and ankle
Figure 21. Original Bromage Scale
Figure 22. Modified Bromage Scale
It measures the complete recovery from regional anesthesia as motor blockade is the last one to go back to normal. The smallest diameter fibers are most sensitive to the effects of local anesthetics Autonomic fibers(sympathetic) will be blocked first, then sensory fibers and then motor fibers. Recovery from the local anesthesia, is also in this sequence.
PHASE II
Assess home readiness using Post Anesthesia Discharge Scoring System (PADS) In the modified PADS aimed at ensuring higher level of safety for patient should have a score of not less than 2 under vital signs and none of the other criteria should be zero, even if the total score 9 is required for discharge
