Surgery: General and Regional Anesthesia

3-3-2 Rule

A method used to predict difficult intubation. A mouth opening of less than three fingers wide, a mandible length of less than three fingers wide, and a distance from hyoid bone to thyroid notch of less than two fingers wide indicate a possibly difficult airway.

Preoperative Evaluation-Airway Examination and Classifications:

After vital signs are obtained, the physical exam begins with the upper airway. The focus is to assess those factors that would make airway control difficult. ● Range of motion of the cervical spine: Patients should beasked to extend and flex their neck to the full range ofpossible motion ● Dentition: dentures, loose teeth, poor dental hygiene. ● Jaw protrusion: ability to protrude the lower incisors past the upper incisors. ● Presence of a beard. ● Examination and classification of the upper airway based on the size of patient's tongue and the pharyngeal structures visible on mouth opening with the patient sitting looking forward. (Mallampati score) ● 3-3-2 Rule

Anesthesia Prevalence and Risk

Anesthesia is performed over 70 million times per year in the US and is remarkably safe. • The overall risk of anesthesia-related death in the healthy patient is low

Preoperative Evaluation - Choice of Anesthesia:

Considerations in choosing an anesthetic technique include: ● Planned surgical procedure • For example abdominal versus extremity ● Patient and surgeon preference • Prior complications - • History of malignant hyperthermia or delayed emergence ● Urgency of the operation ● Postoperative pain management considerations ● Patient age (relative risk factor) must also be included in the decision of choice of anesthetic technique. • Remember, general anesthesia places patient in a controlled critical care state (requiring airway, breathing, and sometimes circulatory support). ● Notation of the proposed type of anesthesia must be entered into record of the preanesthesia evaluation. ● Emergency surgery for patients with a full stomach may necessitate a rapid-sequence general anesthetic (RSI) to protect from pulmonary aspiration.

American Society of Anesthesiologists Physical status classifications (ASA):

Does not assign risk but is a common language used to describe patients preoperative physical status. Above ASA 2 should be seen in preoperative clinic and have preoperative labs drawn beforehand unless emergent.

Postoperative Acute Pain Management - Oral Medications:

For minor procedures, for example, excision of skin lesions, nonsteroidal analgesics may be sufficient. For more intense levels of pain, oral narcotics in combination with acetaminophen are often effective.

Preoperative Evaluation Medication Use:

Heparin: ● Unless absolutely indicated, neuraxial anesthesia (spinal, epidural) should not be performed for at least 12 hours and preferably 24 hours after last dose. ● Spinal hematoma can be devastating • Potentially irreversible paralysis.

Postoperative Acute Pain Management - Specific nerve or plexus block

Local anesthesia block of single nerves or continuous catheter infusion of local anesthetic around major nerve plexuses. • Single injection or placement of a continuous catheter around the femoral nerve for controlling pain from knee surgery.

LEMON

Look Evaluate 3-3-2 Mallampati Obstruction Neck Mobility

Complications of Anesthesia - Awareness:

Many patients are concerned about being aware or waking up during surgery • Aware of surroundings intraoperatively • Typically no pain is felt ● Awareness under general anesthesia is rare ● Certain types of surgery have a higher incidence of intraoperative awareness, including cardiac surgery, major trauma surgery, and obstetrics. ● Preoperative evaluation • Patients with a history of previous intraoperative awareness, substance abuse, chronic use of opioids for pain control have increased risk for intraoperative awareness. ● Preanesthesia preparation • A strict preoperative equipment checklist involving the anesthesia machine and its component • For example, the volatile anesthesia vaporizer agent levels, is mandatory. "You don't want to run out of gas"

Postoperative Acute Pain Management - Intravenous opioids:

Occasionally, one or two intravenous doses of an opioid may be sufficient for postoperative pain. • Patient-Controlled Analgesia (PCA) uses the same or even less total narcotic to control pain and is a safe option. -- • Can set lockout parameters, basal dosing, monitor patient use

Anesthesia

Reversibly blocking pain and awareness during surgical and nonsurgical procedures. Greek origin meaning "without sensation"

Postoperative Acute Pain Management - Epidural/Spinal opiate analgesia:

The application of opioids or narcotics via the neuraxial approach.

Most general anesthetics then include a _______ _______ to facilitate endotracheal intubation or other benefits such as in spine surgery.

muscle relaxant (akinesia)

Preoperative Evaluation

• A preanesthesia/preoperative evaluation is the responsibility of the anesthesiology provider. • This evaluation consists of information gathered from: - • Patient's previous medical record - • History and physical examination - • Medical tests-diagnostic imaging, EKG, labs

Anesthesia Types:

• General anesthetic (drug induced loss of consciousness that requires a controlled airway. Deepest level of sedation) • Spinal/Epidural Block (also called neuraxial blocks collectively) • Monitored anesthesia care (MAC) • -- AKA moderate/conscious sedation

General Anesthesia

● A drug-induced reversible behavioral state consisting of anti-nociception, unconsciousness, amnesia, and akinesia (paralysis) with maintenance of physiologic systems stability. ● "Balanced" general anesthesia uses a combination of drugs, each in an amount sufficient to produce its major or desired effect to the optimum degree and to keep undesirable effects to a minimum.

General Anesthesia Management:

● Administration of IV drugs to induce the state of unconsciousness. (propofol or thiopental commonly used) • If cardiovascular status is compromised, etomidate or ketamine preferred. • Patients receiving propofol may complain of discomfort at the IV site. • Propofol and etomidate may cause movements that appear seizure like. (Extrapyramidal Symptoms or EPS) • Almost all anesthetics are preceded by the administration of an opiate (eg, fentanyl). Helps reduce the amount of induction agent and provides analgesia.

Preoperative Evaluation Control of Comorbidities - Obesity:

● Airway is often difficult to maintain with mask ventilation secondary to decreased neck mobility and adipose tissue. ● Morbidly obese patients may have a higher risk of gastric aspiration and development of aspiration pneumonia (high mortality rate). ● Obesity is a risk factor for OSA • More difficult for airway management • LEMON

General Anesthesia Management - Positioning:

● Assure that the patient is positioned to avoid physical or physiologic complications. ● Careful attention must be paid to adequately protect all potential pressure and vulnerable areas such as elbows, knees, heels, and eyes. • Can develop pressure ulcers if not addressed ● The ulnar nerve is particularly susceptible to injury, as is the brachial plexus when patient's arms are abducted too far. • Padding is used judiciously ● Hemodynamics may also be compromised by position changes that may result indecreased venous return and resultant hypotension.

Complications of Anesthesia - Peripheral Nerve Injury

● Can occur under general anesthesia or a regional technique. ● These injuries are almost always due to patient positioning and the patient's inability to report and respond to abnormal pressure points or awkward position of an extremity. ● The ulnar nerve at the elbow is the most common injury ● Usually report numbness along the course of the nerveome motor weakness may also occur. ● These injuries usually resolve in a short time period ● Abnormal stretching of the brachial plexus from extreme abduction of the arms or chest wall retractors during cardiac surgery may result in more serious injuries

Perioperative complication and deaths are most often a combination of:

● Comorbidities ● Surgical complexity ● Anesthesia effects

Preoperative Evaluation - Preoperative Fasting:

● Fasting helps to reduce the risk of pulmonary aspiration. ● No solid food should be eaten after the evening meal night before. NPO after midnight except for sips of water to take oral medications. • At the minimum, most anesthesiologists delay an anesthetic so that the last solid food was 6-8hours prior to non-emergent surgery.

Mask Inhalation Anesthetic

● General may also be induced by mask using an inhalation anesthetic (isoflurane or sevoflurane). ● This method is commonly used for children. (Easier to put in the IV after they are asleep if needed). ● Inhalation induction takes longer than rapid-sequence induction, and the airway may be unprotected for a longer time. ● A combination of inhalation agent and intravenous agent can be used to induce general anesthesia.

Mallampati Score

● Grade I The soft palate, anterior and posterior tonsillar pillars, and uvula are visible—suggests easy airway intubation. (Easy) ● Grade II Tonsillar pillars and part of the uvula obscured by the tongue. (Should be easy) ● Grade III Only soft palate and hard palate visible. (Hard) ● Grade IV Only the hard palate is visible. (Very challenging airway)

Anesthesia Related Postoperative Problems

● Hypothermia ● Nausea and Vomiting ● Pain Management Complications of Anesthesia ● Awareness/Waking Up ● Peripheral Nerve Injury ● Malignant Hyperthermia (can be life threatening) ● Perioperative visual loss ● Corneal abrasions

Postoperative Nausea and Vomiting

● Identify patients at high risk. (female gender, nonsmoking, and a history of PONV or motion sickness.) ● Reduce baseline risk factors (minimization of intraoperative volatile agents (inhaled anesthetics), opioids, and nitrous oxide; and use of epidurals for postoperative pain management may be the best strategy. ● Administer prophylaxis using one or two interventions at risk for PONV. The 5-HT3 receptor antagonists (ondansetron), dexamethasone, and promethazine are among the most effective first-line antiemetics. Promethazine is also used but remember IV risks. a. Haloperidol can be a second line agent ● Trying to reduce other factors: anxiety of PONV. ● For acute treatment, begin with low-dose 5-HT3 antagonist. • If rescue therapy for patients who have received prophylaxis is required, recommended that the antiemetic(s) chosen should be from a different therapeutic class than the drugs used for prophylaxis.

Wrong Site/Procedure/Person Surgery

● July 2004, JCAHO (Joint Commission) instituted a safety mandate known as the Universal Protocol for preventing wrong site, procedure, person surgery. ● Step 1: Initial verification of the intended patient, procedure, and site of the procedure. • Initially at the time the procedure is scheduled and again at the time of admission into the medical facility the day of surgery. • Anytime care responsibility is transferred to another caregiver, and before the patient leaves the preoperative area (holding) for the operating room. ● Step 2:Marking the operative site. An obvious mark must be made using a marker that is sufficiently permanent to be visible after surgical prep and draping on or near the intended surgical incision site. • This mark should not be an "X" but rather a word or line (representing the proposed incision). This mark should be made by the surgeon performing the procedure. • Patient should participate preferably before sedation to ensure accuracy ● Step 3: A "time out" performed immediately before starting the procedure. ● Must be conducted in the location where the surgical procedure will be done • All members of the care team—surgeon, nurses, anesthesiologists—must actively participate/listen. (Room needs to be quiet) • Verification of patient identity, side and site of surgery, and agreement on the scheduled procedure between the surgical team. • Ensure implants and special equipment are immediately available. • This time out must take place before incision. • JCAHO requires that the time out be documented in the medical record.

Monitored Anesthesia Care (MAC)

● MAC was previously termed "local anesthesia with standby." ● The "standby" is an anesthesia caregiver who monitors the patient's status while the surgeon performs a procedure under local anesthesia +/- conscious (IV) sedation. (Minimal, moderate, deep) • This type of anesthesia is usually requested by the surgeon for patients who may be especially frail in health; it provides the option to convert to a general anesthetic if necessary.

Spinal Anesthesia Complications:

● Most common complication is a spinal headache. • Incidence is very low when smaller-gauge spinal needles are used • More common in young women. • Primarily positional in nature. • Can result in diplopia because of stretching of the sixth cranial nerve as the brain sinks from loss of CSF. • Patients may complain of the headache immediately or a day or two following the operation. ● Conservative treatment • Maintenance of adequate hydration○Remaining recumbent • Analgesic such as acetaminophen • Caffeine sometimes helps ● Severe headache may require a "blood patch" to plug the leak of CSF and is performed by an anesthesiologist. (Patient's own blood is used)

Complications of Anesthesia- Perioperative Visual Loss

● Most commonly associated with prolonged (> 6.5 hours) spinal surgical procedures performed in the prone position associated with large blood losses and cardiac surgery. • Partial or complete visual loss. ● Vision loss seems to be associated with a(n) central retinal artery occlusion (pressure), ischemic optic neuropathy (blood loss), or without any known etiology. ● Risk factors include anemia, vascular disease, and obesity ● Monitoring BP and avoid hypotension, avoid direct pressure on the eye, give blood products if needed. ● No known treatment other than immediate opthamology consult when visual loss realized ● The risk of visual loss should be discussed with patients in the preoperative phase of surgery and anesthesia for those operations that require prolonged prone positioning and cardiac surgery • Part of proper informed consent ● Be aware that corneal abrasions can occur due to drying of eyes in surgery • Less likely if ointment applied preop and eyes taped closed

Completion of Surgery

● Muscle relaxation can be reversed and the anesthetic depth decreased to allow them to return to consciousness. ● Once the return of muscle function is assessed and the patient is able to respond to commands, the endotracheal tube can be removed and the patient closely observed to ensure adequate ventilation. ● Transferred to a stretcher and transported to the PACU (recovery room), accompanied by a member of the anesthesia care team and, commonly, the surgical team (usually circulating nurse) who monitors the patient's condition during transport.

General Anesthesia Management - Difficult Airways:

● Occasionally an unexpected difficult intubation occurs and additional maneuvers may be necessary: • Cricoid manipulation (pressure) - • Helps with aspiration also • Adjustment of the patient's head position • Use of a long, stiff catheter (a bougie) or video laryngoscopy. ● If the airway cannot be secured after multiple attempts, patients can be awakened and a decision made to proceed or to cancel the anesthetic until further workup can be performed. • Cricothyrotomy is generally not an alternative unless surgery is emergent. ● The most serious complication of endotracheal intubation, and the most common cause of serious anesthesia morbidity and mortality, is the failure to secure the airway. ● Other common complications are dental injuries, soft tissue injury to the lips, and laryngospasm on extubation.

Preoperative Evaluation Control of Comorbidities- CAD with Prior Percutaneous Coronary Intervention:

● Patients are usually placed on a dual antiplatelet therapy of aspirin and clopidogrel following angioplasty/stenting. ● The AHA guidelines recommend if the procedure is elective, then the operation should be postponed until the case can be done with aspirin as the only anti-platelet drug. If the operation is emergent, then consideration must be given to the timing of the surgery and the risk of surgical bleeding.

General Anesthesia Management - Airway:

● Patients will be preoxygenated before induction. ● Endotracheal intubation is almost always performed during general anesthesia and is especially important for patients presenting for emergent surgery with presumed full stomach or when positive pressure ventilation is required. ● The laryngeal mask airway (LMA) can also be used to maintain a patent airway. Supraglottic position.

Spinal Anesthesia

● Performed in either the lateral position or with the patient sitting on the table. ● Following sterile prep and local skin anesthetic, a small 25-27 gauge spinal needle is introduced in the lower lumbar spine, and the subdural space is identified by the presence of cerebrospinal fluid (CSF). ● Depending on the planned length of surgery, either lidocaine or bupivacaine (with or without an opiate) is injected. • Lidocaine provides at most 2 hours of anesthesia. • Bupivacaine provides up to 5 hours of anesthesia. ● Once injected, patients are placed in the supine position for 5-10 minutes to allow for proper spread of the local anesthetic. Not head down though. ● BP and HR are monitored • Hypotension and bradycardia can be induced by a sympathectomy due to the cephalad spread of the local. ● During this time, patient movement should be limited.

Preoperative Evaluation-Patient History:

● Previous operations ● Anesthetic types in past ● History of complications from surgery/anesthesia • Allergic reactions • Abnormal bleeding • Delayed emergence (hard to wake up, 30-60 min) • Prolonged paralysis • Difficult airway management • Awareness during surgery ● Comprehensive medical history • Kidney or liver disease • Metabolic abnormalities (diabetes or thyroid disease) • Cardiac conditions (angina, myocardial infarctions, decompensated congestive heart failure, significant arrhythmias, or severe valvular disease) • - Decreased exercise tolerance (red flag for cardiopulmonary issues). Shortness of breath/orthopnea ● Family History • Adverse responses to anesthetics (malignant hyperthermia) ● Social History: particularly smoking, drugs, alcohol use. Chronic opioid use. Certain medications may result in increased or decreased anesthetic requirements and/or prolongation of muscle relaxants. A detailed current medication history is very important. (including OTC, herbal supplements, etc)

Regional/Peripheral Nerve Block

● Regional anesthesia is very useful for procedures on the extremities. ● Upper extremity can be obtained by blockade of the brachial plexus using an interscalene, a supraclavicular, or an axillary approach. ● Lower extremity surgery may be performed utilizing blockade of the lumbar plexus and its major branches. ● Allows for continuous blockade and postoperative pain control. ● The usefulness of these blocks for extremity surgery is limited in time by the use of tourniquets if the patient is to remain awake during the procedure.

Neuraxial Anesthesia for Surgery

● Some operations require no general anesthetic. These include almost any procedure done below the waist, on lower abdomen, and on the upper extremities. ● Neuraxial anesthesia provides muscle relaxation and analgesia ● Advantages: • Allows the patient to be conscious • Fewer thrombotic complications • Less pulmonary compromise • Earlier hospital discharge • Avoidance of airway manipulation

Complications of Anesthesia- Malignant Hyperthermia Treatment:

● Supportive Care-Cool down, Oxygen, Cut off the agents/stop the procedure ● Dantrolene directly interferes with muscle contraction by inhibiting calcium ion release from the sarcoplasmic reticulum, possibly by binding to ryanodine receptor type 1 (RYR-1) which has been mutated. In essence, lowers calcium. • Most PACUs have a MH cart/box • - Know where it is located

Postanesthesia Care Unit (Recovery Room)

● The PACU is where most patients are transferred after surgery. • Some critically ill patients are transported directly to the surgical intensive care unit (SICU). May still be sedated and on ventilator. ● Monitoring of vital signs is begun immediately. Addressing nausea/vomiting, pain control, and temperature are key steps. ● Verbal report is provided to the responsible PACU nurse by a member of the anesthesia care team, surgical team, and/or surgeon. ● The PACU is equipped with essentially the same monitors as the operating room and with the drugs and equipment needed for emergency resuscitation. ● PACUs are staffed with specially trained nurses. ● Patients are continually monitored in the PACU for approximately 1 hour or until they fulfill specific objective criteria. ● Discharge from the PACU requires the clinical judgment of the PACU team. ● Particular attention is focused on the monitoring of oxygenation, ventilation, circulation, level of consciousness, and temperature.

Postoperative Acute Pain Management

● The clinical challenge of providing adequate postoperative pain management is also a major mandate by JCAHO. (Must use caution with numeric pain scores) ● Morphine has been the historical postoperative analgesic, administered either intramuscularly or intravenously. Less euphoric than hydromorphone or fentanyl. ● Every patient is different in the required serum concentration of drug that results in adequate pain control.

Epidural Anesthesia

● The epidural space is between the ligamentum flavum and the dural structures • The subdural space is not entered, so no CSF leak is created with the potential for a spinal headache. ● Analgesia continued by insertion of a small catheter • Additional local anesthetic can be added to move the block to higher spinal levels or to maintain the selected level of anesthesia. • This continuous epidural technique can be used for postoperative pain control.

Preoperative Evaluation Control of Comorbidities - Diabetes Mellitus:

● The most common metabolic abnormality dealt with by anesthesia. ● Anesthesia is responsible for glucose control during the procedure and will monitor at least hourly if patient is on insulin. ● Remember, the patient will be fasting preoperatively and intraoperatively.

Hypothermia

● The operating room temperature is maintained at a colder-than-comfortable level. ● Must be rewarmed to avoid the adverse consequence of shivering (ie, increased oxygen consumption). • Meperidine can reduce shivering. ● Hypothermia may also have an adverse effect on coagulation parameters • Reduces body's ability to form clots ● May delay recovery from anesthesia due to decreased drug metabolism. ● The most effective methods of rewarming are forced-air warming devices (Bair huggers-commonly used name brand) or water-jacket devices.

Preoperative Evaluation-Physical Examination:

● The physical examination focuses on primarily: • Airway (one of the most common causes of adverse outcomes) • Heart and lung exam (include vital signs here) ● Other components include: • Potential intravenous catheter sites/potential sites for regional anesthesia. • Range of motion of limbs must also be noted as this may affect positioning in the operating room. • Any neurologic abnormalities must be noted. (Need to know their baselineas post CVA is a potential complication).

Preoperative Evaluation Control of Comorbidities - Pulmonary Disease:

● The presence of lung disease puts the patient at risk for perioperative complications. ● Pneumonia and prolonged difficulty weaning from the ventilator aretwo of the most common. ● In some instances, arterial blood gas analysis (ABG) or pulmonary function tests (PFT) are necessary.

Epidural Anesthesia Complications

● There is also the potential for misplacement of the catheter or epidural needle in the subdural/subarachnoid space (spinal). Instillation of the larger volumes of local in the subarachnoid space can result in a total spinal or high block with resultant cardiovascular collapse. Therefore, small test doses of local anesthetic are administered. ● Common complication of both spinal and epidural anesthesia is prolonged blockade of parasympathetic fibers that innervate the bladder with resultant urinary retention and the need for a urinary bladder catheter.

Preoperative Evaluation Timing

● Timing of the preop evaluation depends on degree of the planned surgical invasiveness and urgency. ● Time must be allowed to follow up on conditions discovered during the preoperative visit and to answer questions (if possible). ● High surgical invasiveness (Colon resection) • Minimum the day before the procedure. ● Medium surgical invasiveness • The day before or the day of the surgery. ● Low surgical invasiveness (Carpal Tunnel)

Complications of Anesthesia Awareness- Intraoperative Monitoring:

● Utilize all the standard anesthesia patient monitors (EKG, blood pressure measurements, heart rate monitors, continuous agent analyzers, and capnography) and to intermittently assess for purposeful or reflexive movement. ● Monitoring brain electrical activity • Several monitoring devices are claimed to be able to interpret data from the processed, raw electroencephalogram (EEG) of patients and correlate it to the depth of anesthesia.