Surgical stressors include the proinflammatory reaction of tissue injury and associated pain, prothrombosis that puts the brain, heart, and lungs at risk, sodium retention leading to edema in all organ systems, immune dysfunction, and insulin resistance. Collectively, this complex reaction is referred to as the surgical stress response.1
Anesthesia stressors exclusive of surgical stress include intubation and positive pressure ventilation with their effects on the cardiorespiratory system. Lung injury may result from positive pressure ventilation and supplemental oxygen. Central nervous system (CNS) changes from anesthetics coupled with perioperative inflammation can lead to long-lasting reduced cognitive function.
Identification of risks and outcomes other than death and communication of those risks is an essential part of the consent process. The Paling perspective scale (a logarithmic scale) with comparators2 may be useful. The risk of death as a metric can be problematic as many patients interpret death as an “all or none” risk with death versus intact survival as the only possibility. Patients may not appreciate that compared to death, there is a greater risk of surviving surgery with a new disability, new symptoms, or loss of independence leading to discharge to nursing home.
During consultation, identification of surgical and anesthesia risks allows patients to more intelligently examine the risks of surgery versus alternatives. Identifying higher risk patients allows the possibility of preoperative care to reduce risk by altering the patient’s current medication, through presurgical procedures or physiotherapy and exercise therapy to reduce frailty.
Patients with little physiologic reserve may be candidates for medical management or alternative surgical and/or anesthesia modalities. And, identification of high-risk patients allows for planning for postoperative resources such as monitored units or critical care areas.
RISK ASSESSMENT CALCULATORS
Numerous risk scales and calculators are available for use by the perioperative clinician (see Tables 114-1 to 114-3). The most frequently used is the American Society of Anesthesiologists’ (ASA) physical status classification. The five categories range from healthy patient (ASA 1) through moribund (ASA 5). The addition of the letter “E” denotes an emergency procedure. The system does discriminate for complications3 but is too coarse to be a patient communication tool for mortality4 because an inflection point for dramatically increased risk is not seen until ASA 4E (severe disease that represents a constant threat to life, emergency procedure). That the score is not disease-specific but rather closer to a frailty assessment or palliative performance assessment is immaterial. Even as broad descriptors delineate the categories (mild, moderate, or severe disease defined by how activities of daily living are affected), the easily identifiable 4E represents important risk.
TABLE 114-1Considerations for Preoperative Anesthesia Assessment ||Download (.pdf) TABLE 114-1 Considerations for Preoperative Anesthesia Assessment
Request for consultation—either patient- or surgeon-initiated request for preoperative anesthetic care discussion