Risk Factors of PONV

Patients exhibit varying levels of risk for post-operative nausea and vomiting (PONV). Utilizing and interpreting risk scores can assist in making informed therapeutic decisions aimed at reducing PONV incidence within a healthcare facility. The APFL simplified risk score, for instance, incorporates four factors to gauge PONV risk: female gender, history of PONV and/or motion sickness, non-smoking status, and use of postoperative opioids. Depending on the number of risk factors present, patients are categorized as low (0-1), medium (2), or high (3-4) risk. In an adult patient with all four risk factors, the incidence of PONV is as high as 80%. The pathophysiology of PONV is intricate, multifaceted, and not fully understood. Both central and peripheral mechanisms can trigger PONV, with higher cortical centers within the central nervous system capable of inducing nausea and vomiting. Additionally, direct gastric stimulation resulting from gastric trauma or toxins can activate vagal nerve receptors. These vagal nerve afferents, terminating near or within the chemoreceptor trigger zone (CTZ), are capable of initiating nausea and vomiting. Moreover, vestibular disturbances caused by motion or labyrinth disorders also contribute to stimulating PONV.

Beyond the APFL score, several additional factors can influence the risk of PONV but are not encompassed within the APFL criteria. These include being younger than 50 years of age and having a history of chemotherapy-induced nausea and vomiting, both of which significantly elevate the risk. The use of volatile anesthetics is also associated with a higher incidence of PONV, although this risk primarily affects the early post-operative period.