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A4 Anesthesia
Pre-Operative Optimization Toronto Notes 2019
Pre-Operative Investigations
• routinepre-operativeinvestigationsareonlynecessaryiftherearecomorbiditiesorcertainindications
Table 1. Suggested Indications for Specific Investigations in the Pre-Operative Period
Impact of Anesthesia Management Characteristics on Severe Morbidity and Mortality
Anesth 2005;102:257-268
Study: Case-control study of patients undergoing anesthesia.
Patients: 807 cases and 883 controls were analyzed among a cohort of 869,483 patients undergoing anesthesia between 1995-1997.
Cases were defined as patients who either remained comatose or died within 24 h of receiving anesthesia. Controls were defined as patients who neither remained comatose nor died within 24 h of receiving anesthesia.
Intervention: General, regional, or combined anesthesia to patients undergoing a surgical procedure.
Main Outcome: Coma or death within 24 h of receiving anesthesia.
Results: The incidence of 24 h post-operative death was 8.8 per 10,000 anesthetics (95% CI 8.2-9.5) and the incidence of coma was 0.5 (95% CI 0.3-0.6). Anesthesia management risk factors that were associated with a decreased risk of morbidity and mortality were equipment check with protocol and documentation, directly available anesthesiologist with no change during anesthesia, 2 persons present at emergence of anesthesia, reversal of muscle relaxation, and post-operative pain medication.
Aspirin® in Patients undergoing Non-Cardiac Surgery
NEJM 2014; 370:1494-1503
Purpose: This study evaluated the effect of low- dose ASA on the risk of death or non-fatal MI in 10,010 patients undergoing non-cardiac surgery. Patients were randomized into two groups in a double-blind process.
Methods: RCT comparing ASA versus placebo taken shortly before surgery and in the early post-operative period. The primary outcome was a composite of death or non-fatal MI.
Results: Death or non-fatal MI occurred in 7.0% in the ASA group and 7.1% in the placebo group. Major bleeding was more common in the ASA group than the placebo group.
Conclusion: Administration of ASA before surgery and throughout the early post-surgical period had no significant effect on the incidence of death or MI but increased the risk of major bleeding.
Test CBC
Sickle Cell Screen
INR, aPTT
Electrolytes and Creatinine
Fasting Glucose Level Pregnancy (β-hCG) ECG
Chest Radiograph
Indications
Major surgery requiring group and screen or cross and match; chronic cardiovascular, pulmonary, renal, or hepatic disease; malignancy; known or suspected anemia; bleeding diathesis or myelosuppression; patient <1 yr of age
Genetically predisposed patient (hemoglobin electrophoresis if screen is positive) Anticoagulant therapy, bleeding diathesis, liver disease
Hypertension, renal disease, DM, pituitary or adrenal disease; vascular disease, digoxin, diuretic, or other drug therapies affecting electrolytes
DM (repeat on day of surgery) Women of reproductive age
Heart disease, DM, other risk factors for cardiac disease; subarachnoid or intracranial hemorrhage, cerebrovascular accident, head trauma
Patients with new or worsening respiratory symptoms/signs
Guidelines to the Practice of Anesthesia Revised Edition 2013. Supplement to the Canadian Journal of Anesthesia, Vol 60, Dec. 2013. Reproduced with permission © Canadian Anesthesiologists’ Society
American Society of Anesthesiology Classification
• commonclassificationofphysicalstatusatthetimeofsurgery
• agrosspredictorofoveralloutcome,NOTusedasstratificationforanestheticrisk(mortalityrates) • ASA1:ahealthy,fitpatient
• ASA2:apatientwithmildsystemicdisease
■ e.g. controlled Type 2 DM, controlled essential HTN, obesity, smoker • ASA 3: a patient with severe systemic disease that limits activity
■ e.g. stable CAD, COPD, DM, obesity
• ASA4:apatientwithincapacitatingdiseasethatisaconstantthreattolife
■ e.g. unstable CAD, renal failure, acute respiratory failure
• ASA5:amoribundpatientnotexpectedtosurvive24hwithoutsurgery
■ e.g. ruptured abdominal aortic aneurysm (AAA), head trauma with increased ICP
• ASA6:declaredbraindead,apatientwhoseorgansarebeingremovedfordonationpurposes • foremergencyoperations,addtheletterEafterclassification(e.g.ASA3E)
Pre-Operative Optimization
• ingeneral,priortoelectivesurgery:
■ any fluid and/or electrolyte imbalance should be corrected
■ extent of existing comorbidities should be understood, and these conditions should be optimized
prior to surgery
■ medications may need adjustment
Medications
• payparticularattentiontocardiacandrespiratorymedications,opioidsanddrugswithmanyside effects and interactions
• pre-operativemedicationstoconsider
■ prophylaxis
◆ risk of GE reflux: sodium citrate and/or ranitidine and/or metoclopramide 30 min-1 h prior to
surgery
◆ risk of infective endocarditis, GI/GU interventions: antibiotics
◆ risk of adrenal suppression: steroid coverage
◆ anxiety: consider benzodiazepines
◆ COPD, asthma: bronchodilators
◆ CAD risk factors: nitroglycerin and β-blockers
• pre-operativemedicationstostop
■ oral antihyperglycemics: do not take on morning of surgery
■ ACEI and angiotension receptor blockers: do not take on the day of surgery (controversial – they
increase the risk of hypotension post induction but have not been shown to increase mortality or
adverse outcomes; therefore, some people hold and some don’t)
■ warfarin (consider bridging with heparin), anti-platelet agents (e.g. clopidogrel), Xa inhibitor, direct
thrombin inhibitors