Abstract
Preanesthetic evaluation is a process of clinical assessment, risk stratification, and optimization before surgery to reduce the perioperative morbidity and mortality. Most neurosurgical procedures are considered to be moderate- to high-risk surgeries. Patients undergoing neurosurgical procedures will have multiple medical comorbidities, and all these problems need to be evaluated and optimized before surgery. Apart from these patient-related risk factors, each neurosurgical procedure carries its inherent risk and requires specific preoperative evaluation and optimization. History and clinical examination are the keyhole factors during preoperative evaluation. Cardiovascular and respiratory examination should be done prior to neurological examination to integrate other physical findings with the presenting neurological abnormality. Reviewing the laboratory and radiological investigation and incorporating these investigations with clinical findings help the anesthesiologist to stratify the risk associated with surgery. Risk stratification not only provides information to both the patient and the neurosurgeon to understand the benefit vs. risk of each neurosurgical procedure and also helps the perioperative physician to optimize the patient before surgery.
Keywords
Neurosurgery, Preanesthetic evaluation, Preoperative optimization, Risk reduction strategy, Risk stratification
Outline
Introduction 209
Preoperative Evaluation of Patient-Related Risk Factors 210
Preoperative Evaluation of Cardiac Risk in Neurosurgical Patients 210
Risk Assessment Tools for Estimating Cardiac Risk 210
Assessment of Functional Capacity 211
Indication for Cardiac Testing During Preoperative Evaluation 211
Evaluation of Pulmonary Risk in Patients Undergoing Neurosurgical Procedure 211
Preoperative Evaluation of Patients With Obstructive Sleep Apnea 213
Various Screening Tools for the Diagnosis of Obstructive Sleep Apnea 213
Specific Issues to Be Considered During Preoperative Evaluation of Patients With Obstructive Sleep Apnea 213
Preoperative Evaluation of Patients With Diabetes and Hypertension 213
Preoperative Medication Evaluation 214
Comprehensive Neurological Examination for Neuroanesthesiologist 214
Preoperative Evaluation of Specific Neurosurgical Conditions 217
Preoperative Evaluation of Patients With Supratentorial and Posterior Fossa Tumor 217
Preoperative Evaluation of Patients for Awake Craniotomy 219
Preoperative Evaluation of Patients With Pituitary Diseases 220
Preoperative Evaluation of Patients With Suprasellar Lesions 220
Preoperative Evaluation of Patients With Epilepsy 222
Preoperative Evaluation of Patients With Subarachnoid Hemorrhage 223
Preoperative Evaluation of Patients With Arteriovenous Malformation 224
References 225
Introduction
A routine preanesthetic evaluation is a process that includes clinical assessment, risk stratification, and optimization before surgery. The primary aim of the preanesthetic evaluation is to reduce the perioperative morbidity and mortality. This involves many steps, which include:
- 1.
Establishing rapport with the patient and family, explaining the process of surgery, anesthesia, and recovery.
- 2.
Reviewing the past medical, surgical, personal and family history and history of medication allergy and the lists of current medication.
- 3.
A through general and clinical examination focusing on cardiopulmonary system and nervous system.
- 4.
Review of investigations and to assess whether further investigations or multidisciplinary care is needed, which would help to improve the patient condition.
- 5.
Risk-stratifying the patient for perioperative morbidity and mortality using clinical and laboratory data for the proposed surgical procedure.
- 6.
Optimization of the patient using the risk reduction strategies.
- 7.
To plan the type of anesthesia after assessing the risk/benefit of each anesthetic technique for that particular procedure.
- 8.
Utilization of best available resources to maximize the safety, to reduce the morbidity and mortality, and to speed up the recovery by providing adequate postoperative pain management.
- 9.
Getting an informed consent after explaining the risk and benefits of anesthesia technique and the need for invasive monitoring, blood transfusion (if applicable), and its associated risks.
Preanesthetic evaluations should be performed well ahead of the surgical procedure especially for high-risk patients [American Society of Anesthesiologists (ASA) grades 3 and 4] thereby allowing time for preoperative optimization, which has been shown to reduce the perioperative morbidity and mortality. Patients with ASA grades 1 and 2 can undergo preoperative evaluation either on the day of surgery or the day before surgery. ASA classification of physical status is a universally accepted grading system to stratify the patient’s preexisting health condition. Although it was not designed for outcome prediction, there has been a good correlation between the grading and perioperative morbidity and mortality.
Most patients undergoing neurosurgical procedures will have an underlying medical comorbidities such as diabetes, hypertension, ischemic heart diseases (IHD), obstructive sleep apnea (OSA), and chronic obstructive pulmonary disease (COPD), or bronchial asthma and seizures. These medical conditions require more intense scrutiny than the pathological process to prevent perioperative morbidity and mortality. Each neurosurgical procedure carries its inherent risk and requires specific preoperative evaluation and optimization. So, during the preoperative evaluation both patient- and procedure-related factors should be kept in mind and optimized accordingly.
Preoperative Evaluation of Patient-Related Risk Factors
In this section, the preoperative evaluation of patient-related risk factors focusing on cardiac and respiratory conditions, OSA, diabetes, and hypertension are discussed.
Preoperative Evaluation of Cardiac Risk in Neurosurgical Patients
Most neurosurgical procedures are considered to be intermediate- to high-risk surgeries. Patients with cardiac diseases undergoing neurosurgical procedure can have aggravation of cardiac dysfunction due to the systemic effect of raised intracranial pressure (ICP) (tumor, head injury) or catecholamine surge [in subarachnoid hemorrhage (SAH)] or autonomic dysfunction (Parkinson disease, cervical myelopathy, and brainstem lesion) leading to increased morbidity. Long-standing hypertension and diabetes are common in patients undergoing carotid endarterectomy and spine surgery, and these patients are more prone for IHD. Identification of cardiac risk associated with each neurosurgical procedure provides information to both the patient and the surgeon, which in turn helps them to understand the benefit vs. risk of a procedure. Cardiac interventions even before the surgery in certain high-risk cases decreases the perioperative morbidity and mortality.
Risk Assessment Tools for Estimating Cardiac Risk
There are various risk assessment tools available to assess the cardiac risk in patient undergoing neurosurgery. These tools use the information obtained from the history, physical examination, electro- and echocardiogram, and type of surgery. The various tools are given below.
- 1.
Revised Cardiac Risk Index ( Lee’s ) tool : This is the most commonly used tool and was originally published in 1999; it has been used to assess the risk for >15 years. It uses six factors such as high-risk surgery, history of IHD, congestive heart failure (CHF), cerebrovascular diseases, diabetes or insulin, and presence of high creatinine to estimate the cardiac risk. Using the aforementioned predictors, the estimated risk of cardiac death, nonfatal cardiac arrest, and nonfatal myocardial infarction (MI) following the elective surgical procedure are 0.4% [95% confidence interval (CI): 0.1–0.8] if there is no risk factor and 1.0% (95% CI: 0.5–1.4) if there is one risk factor. The risk increases to 2.4% (95% CI: 1.3–3.5) and 5.4% (95% CI: 2.8–7.9) if there are two and three or more risk factors, respectively.
- 2.
American College of Surgeons-National surgical Quality Improvement Program (ACS-NSQIP) universal surgical risk calculator : This surgical risk calculator model is a Web-based tool consisting of 20 patient factors such as body mass index (BMI), age, sex, ASA classification, functional status, prior cardiac history, and so on. The calculator then provides a risk of a major adverse cardiac event for the patient. This model had excellent performance for mortality, morbidity, and six additional complications. Limitations of this tool are that it is more cumbersome and its external validity is still questionable.
- 3.
Gupta myocardial infarction/cardiac arrest (MICA) – NSQIP database risk model : This risk model uses the following five factors to assess the risk of perioperative MI and cardiac arrest. They are (1) type of surgery, (2) dependent functional status, (3) abnormal creatinine, (4) American Society of Anesthesiologists’ class, and (5) increased age.
Assessment of Functional Capacity
Assessment of patients functional capacity is the next step in cardiac evaluation, expressed in metabolic equivalents (METs). One MET is defined as 3.5 mL of O 2 uptake/kg/min in a sitting position, which is a resting oxygen uptake. Duke activity state Index is one of the most frequently used scales to assess the functional status. Ability to take care of oneself, such as eating, dressing, or using the toilet is considered 1 MET. Walking up a flight of steps or a hill or walking on level ground at 3–4 mph is considered as 4 METs. Participating in strenuous sports such as swimming, singles tennis, football, basketball, and skiing is equivalent to >10 METs. Ability to do an activity that requires >4 METs indicates good functional activity. Assessing the functional capacity in patients with walking disability such as paraplegia or hemiplegia can be done by using bicycle or arm ergometry stress testing. After determining the cardiac risk and functional capacity, one can follow the multistep algorithm provided by the American College of Cardiology (ACC) and American Heart Association (AHA) for determining the need for further preoperative cardiac evaluation before proceeding with surgery. Refer ACC and AHA 2014 guideline for details.
Indication for Cardiac Testing During Preoperative Evaluation
Electrocardiogram ( ECG ): All patients with cardiac problems such as IHD, arrhythmias, valvular heart diseases (VHD), and peripheral arterial diseases should obtain a baseline ECG to compare the changes that occur during the perioperative period. Patients with neurological problem such as raised ICP or SAH have underlying cardiac dysfunction, they often need baseline ECG.
Echocardiography : It is indicated to assess the ventricular function in symptomatic patients (dyspnea or heart failure), patients with VHD, and patients with past history of previously documented cardiac dysfunction with no assessment within 1 year.
Stress echocardiography : Although there is a correlation between the degree of MI and the prognosis, there is no evidence that prophylactic revascularization at the time of surgery improves outcomes. So, further cardiac evaluation (stress echocardiography or 24-h ambulatory monitoring) is only indicated in patients with known IHD with recent deterioration.
Evaluation of Pulmonary Risk in Patients Undergoing Neurosurgical Procedure
The incidence of perioperative pulmonary complications (POPCs) are high in patients with preexisting lung (obstructive, restrictive) diseases. Perioperative hypoxia and hypercapnia not only affect the cardiorespiratory status but also can aggravate the existing neurological illness. Neurosurgical patients are more prone to pulmonary complications because of low Glasgow Coma Scale (GCS) score (tumor, head injury, seizure, SAH), lower cranial nerve dysfunction in posterior fossa tumors or cranio vertebral junction anomalies causing aspiration pneumonia, or the presence of a high cervical or thoracic spine lesion causing cord compression leading to restrictive lung diseases.
POPCs contribute significantly to overall perioperative morbidity and mortality in the neurosurgical population. According to the NSQIP report, POPCs are the costliest of all postoperative medical complications (including cardiac, thromboembolic, and infectious) and resulted in the longest length of hospital stay. POPC is defined as any pulmonary disease or dysfunction that is clinically significant or adversely affects the clinical course of the patient. They are (1) atelectasis, (2) infection including bronchitis and pneumonia, (3) prolonged mechanical ventilation (>48 h), (4) respiratory failure, (5) exacerbation of underlying chronic lung disease, and (5) bronchospasm.
Preoperative Pulmonary Risk Stratification
A complete history and physical examination are the most important elements of preoperative pulmonary risk assessment. Based on the available literature, the risk factors for POPC are classified into definite and probable, which are listed in Table 11.1 . There are many risk prediction tools available to stratify the postoperative pulmonary risk ; they are (1) ARISCAT (Canet) risk index used for predicting POPC, (2) Arozullah index for predicting postoperative pneumonia and respiratory failure, (3) Gupta calculator for predicting postoperative pneumonia and respiratory failure, and (4) ASA grading for predicting POPC.
- 1.
ARISCAT ( Canet ) risk index : It predicts the overall incidence of postoperative pulmonary complications using the patient’s age, preoperative oxygen saturation, recent respiratory infection, preoperative anemia, type of surgical incision, and duration of surgery. It has a total of 165 points; patients with low scores (<26 points) are considered as low risk and patients with high score (>45 points) are considered as high risk for POPC. According to this risk index the incidence of POPC is 1.6%, 13.3%, and 42.2% for low-, intermediate-, and high-risk classes. It is a very simple tool that calculates the risk manually at the bedside using the readily available clinical information. The limitation of this tool is it that includes even the minor complications such as wheezing treated with bronchodilators, which is not clinically significant.
- 2.
ASA classification : ASA classification has been shown to predict the postoperative pulmonary complication. The incidence of POPC for ASA grades 1, 2, 3, and 4 are 1.2%,5.4%, 11.4%, and 10.9%, respectively.
| Definite Risk Factors | Probable Risk Factors |
|---|---|
|
|
Indication for Preoperative Pulmonary Testing
- 1.
Chest X – ray : Recent chest X-ray (within 6 months) is warranted for patients older than 50 years with cardiopulmonary diseases undergoing major surgery.
- 2.
Pulmonary function test ( PFT ): Based on a systematic review, the American College of Physicians guideline recommends that PFT should not be used for risk stratification. It should be reserved to determine the clinical cause only in patients with COPD and asthma, in whom clinical evaluation cannot determine the reduction in airflow obstruction, and in patients with unexplained dyspnea or poor exercise tolerance.
- 3.
Arterial blood gas ( ABG ) analysis : In patients with severe COPD, PaCO 2 >45 mmHg is one of the probable risk factors for POPC. However, routine ABG is not warranted for risk stratification.
Preoperative risk reduction strategies to reduce POPCs are as follows :
- 1.
Smoking cessation for more than 8 weeks prior to surgery has been shown to reduce the perioperative morbidity and mortality.
- 2.
Preoperative administration of inhaled bronchodilators and glucocorticoids in patients with COPD and asthma.
- 3.
Treating the exacerbation of asthma and COPD with systemic glucocorticoids (e.g., prednisone 40 mg/day for 5 days) and treating the lower respiratory tract infection with antibiotics and postponing the elective surgery.
- 4.
Preoperative education regarding lung expansion maneuvers and initiation of chest physiotherapy such as aerobic exercises, breathing exercises, and inspiratory muscle training.
Preoperative Evaluation of Patients With Obstructive Sleep Apnea
OSA is a sleep-related breathing disorder characterized by repetitive episodes of apnea or hypopnea due to upper airway obstruction during sleep. It is classified into mild, moderate, and severe according to the Apnea–Hypopnea Index (AHI). AHI of 5–15 per hour is mild OSA, AHI of 15–30 per hour is considered as moderate OSA, and AHI >30 per hour is considered as severe OSA.
Over the past two decades, with the parallel increase in obesity, the prevalence of OSA is rapidly increasing. Studies have reported that the incidence of OSA is >30% in neurosurgical population. Patients with Cushing disease, acromegaly, intractable epilepsy, and intracranial tumors are more prone to OSA. Studies and meta-analysis have concluded that the incidence of postoperative desaturation, respiratory failure, postoperative cardiac events, and intensive care unit (ICU) transfers were higher in patients with OSA. Over half of patients with OSA who present for surgery are undiagnosed ; the complication rates are two- to fourfold higher when compared with those who are optimized preoperatively. OSA-related postoperative complications are common because of the following reasons:
- 1.
Administration of perioperative medication (sedatives, opioids, neuromuscular blocking drugs)
- 2.
Worsening of airway edema (endotracheal tube placement, throat pack application, tracheal retraction, head-down positioning, prone position)
- 3.
Discontinuation of continuous positive airway pressure (CPAP) therapy in patients undergoing transsphenoidal surgery
- 4.
Sleep deprivation due to pain, anxiety, and ICU environment can all lead to increased rapid eye movement sleep, which increases the OSA episodes
- 5.
Presence of OSA-related comorbidities [obesity systemic hypertension, obesity hypoventilation syndrome (OHS), pulmonary hypertension, cardiac arrhythmias, coronary artery disease, and heart failure]
Various Screening Tools for the Diagnosis of Obstructive Sleep Apnea
- 1.
STOP – BANG questionnaire : It is a very simple tool to screen, and it is the most frequently used questionnaire in our practice. It requires “Yes” or “No” responses to eight questions about s noring, t iredness, o bserved apnea, and blood p ressure; b ody mass index>35 kg/m 2 , a ge >50 years, n eck circumference >40 cm, and male g ender. Patients with zero to two positive responses are considered “low risk,” those with three to four are considered “intermediate risk,” and those with five to eight positive responses are considered “high risk for OSA.” Patients with raised serum bicarbonate level (≥28 mmol/L) with a STOP-BANG score of ≥3 are equals to STOP-BANG score of ≥5. These patients are considered to have moderate to severe OSA.
- 2.
Sleep Apnea Clinical Score —Flemons’ screening tool : It is four-item questionnaire (habitual snoring, nocturnal gasping/choking, neck circumference, hypertension) with the score ranging from 0 to 100. Values >15 indicate that the patient is at high risk for OSA.
- 3.
Berlin Questionnaire : This uses items such as snoring, excessive daytime sleepiness, sleepiness while driving, apnea during sleep, hypertension, and BMI to stratify patients as having a high or low risk for OSA.
Specific Issues to Be Considered During Preoperative Evaluation of Patients With Obstructive Sleep Apnea
While evaluating patients with OSA, the symptoms and signs of OSA; the duration, severity, and presence of OSA-related comorbidities, type of treatment given (CPAP or bilevel positive airway pressure); response to treatment; and the details of current airway pressure setting all, need to be documented. Patients with long-standing OSA are more prone for OHS and pulmonary hypertension. Elevated bicarbonate level and hypoxemia are the indicators OHS. Presence of OHS and pulmonary hypertension indicates the need for echocardiography. Patients with severe OSA have to be admitted and optimized at least 1 week prior to surgery. Practice Guidelines for the Perioperative Management of Patients With OSA—an updated report by the American Society of Anesthesiologists Task Force—was published in 2014 based on expert opinion, literature review, and consensus.
Preoperative Evaluation of Patients With Diabetes and Hypertension
Detailed discussion on preoperative evaluation on both these conditions are beyond the scope of this chapter. Specific concerns regarding diabetes and hypertension and their anesthetic implications are given in Tables 11.2 and 11.3 .
| Specific Concerns | Details Regarding Specific Points |
|---|---|
| Patients with type I DM are more prone for perioperative complications. Longer duration of diseases is associated with increased perioperative complications |
| Insulin: Type of insulin, dose, frequency, timing. OHA: Type, dose, frequency, complication of drugs (lactic acidosis) |
| Trends and ranges of blood glucose level during the immediate preoperative period including HbA 1 C (reveals 3 months’ control). Incidence of hypoglycemia, and its severity Perioperative administration of dexamethasone can cause aggravation of hyperglycemia |
| Look for signs of neuropathy, retinopathy, nephropathy, peripheral vascular diseases, and IHD—increases the perioperative morbidity and mortality |
| Specific Concerns | Details Regarding Specific Points |
|---|---|
| Long-standing hypertension is associated with LVH and its associated complication (systolic and diastolic dysfunction), which increases the perioperative morbidity |
| β-Blocker/calcium channel blocker/ACE inhibitor/ARB/central sympatholytic drugs Drug effects and its anesthetic implications are discussed in detail in medication evaluation section |
| Blood pressure trends during the perioperative period should be noted especially in the presence of white coat hypertension |
| Look for LVH as well as systolic and diastolic dysfunction. Presence of these complications are associated with increased perioperative morbidity |
Preoperative Medication Evaluation
Patients undergoing neurosurgical procedures will be on multiple medication, either for their neurological diseases itself (anticonvulsants, antiedema drugs, H 2 blockers, or proton pump inhibitors) or for their associated medical comorbidities. Most medications are known to cause interaction with anesthetics. There are large variations in recommendation among the anesthesiologist in regard to continuing/discontinuing certain drugs during the perioperative period. Every physician should balance the risks vs. benefits of continuing/discontinuing the drug during the perioperative period. Commonly used drugs in neurosurgical practice and their anesthetic interactions and the recommendation regarding whether they need to be continued or stopped before surgery are given in Table 11.4 . These recommendations are based on expert opinions and their reviews and the theoretical considerations.
| Drug | Strategy to Continue Yes/No | Perioperative Anesthetic Implications | |
|---|---|---|---|
| Benefits/Anesthetic Drug Interaction | Risks | ||
| Β-Blockers | Yes | Decreases the myocardial ischemia by reducing the oxygen demand | Increases the risk of perioperative bradycardia and hypotension |
| Controls and prevents arrhythmias | |||
| Nonselective β-blockers can interact with epinephrine or ephedrine and cause hypertensive crisis due to unopposed alpha stimulation | |||
| Perioperative initiation reduces the cardiovascular morbidity but increases the risk of stroke (POISE I trial) in high-risk cardiac patients. | |||
| Abrupt withdrawal increases the cardiovascular morbidity | |||
| α-Blocker (clonidine) | Yes | Improves the perioperative outcome (proven only in a smaller studies) | Increases the incidence of hypotension and nonfatal cardiac arrest. (POISE II trial) |
| Abrupt withdrawal can cause rebound hypertension and myocardial ischemia | Perioperative initiation is not warranted | ||
| Calcium channel blocker | Yes | No interaction with anesthetic drugs | Abrupt withdrawal can cause coronary spasm |
| Since it decreases the platelet aggregation, there is a conflicting opinion regarding its bleeding risk | |||
| ACE inhibitor and angiotensin II receptor blocker | Yes/no | Decision to continue or discontinue depends on the patient’s condition | Increased incidence of perioperative hypotension and the need for inotropes |
| According to ACC/AHA 2014 guidelines—to continue if the patient is taking for hypertension or CHF | Withdrawal can cause postoperative hypertension | ||
| Risk vs. benefits of intraoperative hypotension should be kept in mind | |||
| Diuretics | Yes/no | No consensus available regarding discontinuation | Increased incidence of perioperative hypotension and hypokalemia |
| HMG CoA reductase inhibitors (statins) | Yes | Reduces the cardiovascular and cerebrovascular morbidity because of its cholesterol-lowering effect, plaque stabilization, antiinflammatory, and decreased thrombogenesis effects | |
| No interaction with anesthetic drug | |||
| OHAs | No | No interaction with anesthetic drugs | Intraoperative hypoglycemia with sulfonylureas |
| Increased incidence of lactic acidosis with metformin | |||
| Thiazolidinediones worsen the peripheral edema and fluid retention and HF | |||
| Sodium–glucose cotransporter 2 inhibitors increase the risk of hypovolemia | |||
| DPP-IV inhibitors and GLP-1 analogs alter the GI motility and worsen the postoperative state | |||
| AEDs | Yes | ||
| Carbamazepine, phenytoin, Hepatic microsomal isoenzyme (CYP 450) inducer | Drugs that causes enzyme induction accelerate the metabolism of drugs metabolized by this enzyme system, thereby increasing the requirement of propofol, opioid, and muscle relaxants | ||
| Oxcarbamazepine, eslicarbazepine: weak enzyme inducer | |||
| Sodium valproate: enzyme inhibition | Drugs that cause enzyme inhibition decrease the metabolism of drugs metabolized by this enzyme system, thereby decreasing the requirement of propofol, opioid, and muscle relaxants | ||
| Gabapentin, lamotrigine, levetiracetam, tiagabine, vigabatrin: do not affect hepatic enzyme system | |||
| Aspirin (low dose 75–300 mg) | No | Neurosurgical operations are closed space surgery and considered to be moderate- to high-risk surgeries, aspirin has to be stopped 7 days prior to surgery | Increases the bleeding risk if it is continued. |
| Platelet P2Y 12 receptor blockers | Increased bleeding risk | ||
| Clopidogrel | No | Clopidogrel to be stopped 5–7 days prior to surgery | |
| Ticlopidine | No | Ticlopidine had to be discontinued 10 days prior to surgery | |
| Dipyridamole | No | Dipyridamole has to be discontinued 2 days prior to surgery | |
| Aggrenox (Aspirin + dipyridamole) | No | Aggrenox had to be stopped 7–10 days prior to surgery | |
| H2 blockers and proton pump inhibitors | Yes | Decreases the mucosal damage, decreases the gastric secretion, and increases the gastric pH thereby decreasing the chance of aspiration pneumonitis | Cimetidine is the only drug that interferes with many drug metabolism |
| TCAs (Imipramine, amitriptyline, nortriptyline, desipramine, and clomipramine) | No | Abrupt withdrawal causes insomnia, nausea, headache, increased salivation, and sweating and should be avoided | Increases the risk of perioperative arrhythmia in combination with volatile anesthetics and sympathomimetics |
| With pethidine and tramadol, it can cause serotonin syndrome | |||
| SSRIs | No | Abrupt discontinuation can lead to dizziness, chills, muscle aches, and anxiety | SSRIs increases the bleeding risk so, it has to be tapered and stopped 2–3 weeks earlier. It has to be replaced with another regime of antidepressant to avoid exacerbation of mood disorder |
| (Paroxetine, fluvoxamine, sertraline, fluoxetine) | |||
| MAO inhibitors | No | Causes accumulation of biogenic amines in central and autonomic system neurons by causing irreversible inhibition of MAO | Concomitant administration of sympathomimetic agents can result in hypertensive crisis |
| (Isocarboxazid, pargyline, phenelzine, and tranylcypromine) | Recovery of MAO function takes 2 weeks after discontinuation of the drug. So, drug should be tapered and stopped 2 weeks before elective surgery | Coadministration of pethidine can cause type I serotonin syndrome | |
| By inhibiting the hepatic microsomal enzyme system responsible for opioid metabolism, it can cause type II reaction. (sedation, respiratory depression, and cardiovascular collapse) | |||
| Antipsychotics | Yes/no | Antipsychotic effectively controls the psychoses in vulnerable patients. | Both typical and atypical antipsychotic drugs are associated with an increased risk for sudden death because of QT prolongation and arrhythmogenic effect |
| Should be used cautiously in the perioperative settings. Frequent ECG monitoring is needed especially in the perioperative settings | Potentiates the effect of sedatives, anaesthetics, and analgesics | ||
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