Risk Factors for Postoperative Nausea and Vomiting

1. Risk Factors for Postoperative Nausea and Vomiting Review Article Anesth Analg 2006;102;1884-98

2. PONV - most frequent side effect Unselected inpatients -> 30% 고 위험군 -> 70% 이상 • In a preoperative survey, emesis -> the most undesirable nausea -> the fourth most undesirable of 10 negative outcomes (pain -> third) • 하지만, 대다수의 환자는 예방이 없어도 PONV가 발생하지 않기 때문에 예방이 필요 없다. 부작용을 일으킬 수 있고 노력과 비용이 필요할 수 있다. universal efficacy가 부족 (monotherapy)

3. 따라서 PONV를 경험할 것 같은 환자에서 예방하는 것이 중요 - combination therapy or "multimodal management" (가장 효과적인 방법이지만, 비용이 많이 들 수 있고 부작용이 더 발생할 수 있음) • PONV의 risk factor에 대한 지식이 필요함 • PONV의 risk factor에 대한 이해는 불완전함 - multifactorial nature of PONV (<- multiple receptor, stimuli와 관련) - PONV와 관련있는 neurotransmitter -> serotonin, dopamine, muscarine, acetylcholine, neurokinin-1, histamine, and opioids - vestibular-cochlear, glossopharyngeal, or vagus nerves의 stimulation도 관련됨

4. Definition and Classification of PONV • nausea - subjective sensation of an urge to vomit, in the absence of expulsive muscular movements (심할 때 -> increased salivary secretion, vasomotor disturbances, and sweating) • Vomiting or emesis - the forcible expulsion through the mouth of the gastric contents • Retching - an unproductive effort to vomit • Retching + vomiting -> emetic episodes

5. early - occuring up to 2 to 6 hr after surgery late - occurring up to 24 or 48 hr • early와 late는 어느 정도 다른 기전을 갖고 있음 - volatile anesthetics -> early PONV - opioid-induced symptom, motion sickness -> late PONV

6. Risk Factor for PONV Overview • single potential factor -> multiple risk factor • potential risk factors may be classified as patient-, surgery-, or anesthesia-related as fixed or variable • most patient and surgical technique-related factors -> fixed • some other surgery-related factors and some anesthesia-related factors -> variable Key Risk Factor Findings to Date • well established, possible, disproved

7. Patient-Related Factors • strongest risk factor -> female gender from puberty on (2-4배의 증가된 PONV risk를 보임) • prepubescent girls에서는 PONV가 잘 발생하지 않음 (hormonal factor와 관련됨을 의미) • early stage of the menstrual cycle -> disproved • nonsmoking status -> 1.5-2.5배 history of PONV, motion sickness -> 1.8-3.1배 • childhood after infancy and younger adulthood -> independent PONV risk factors (하지만 age는 risk scoring system에서 minority에 속함)

8. Possible risk factors • Disproved risk factors

9. Surgery-Related Factors • increasing duration of surgery - independent PONV risk factor • type of surgery - controversial

10. Possible risk factors

11. Anesthesia-Related Factors • Well established risk factor

12. Possible risk factors • Disproved risk factors

13. Limitation of Modern Research and Suggestions for future investigation • Five limitation 1) epidemiological approach -> genetic and other molecular biological patient characteristics have not been extensively examined 2) the difficulty of controlling for subtle clinical factors 3) variation in outcomes and data collection methods (nausea와 emetic episode는 pathophysiological differences nausea -> subjective feeling and a conscious cortical activity emetic episode -> autonomic reflex, brainstem에서 조절)

14. Stadler et al. - female gender, nonsmoking status, use of postoperative morphine analgesia, general versus regional anesthesia, and urological versus ENT procedures -> independent predictors of both symptoms - abdominal or gynecological versus ENT procedures and Hx of migraine -> significant or near-significant predictors only for nausea 한편, nausea없이 vomiting하는 경우는 드물기 때문에 nausea를 potential vomiting을 위한 symptom으로 봐야 한다는 의견도 있음 recorded or volunteered symptoms 특정 질문에 대한 대답으로 정의 antiemetics를 사용한 경우로 정의

15. 4) 대부분의 연구가 adult inpatients를 대상으로 함 outpatients와 children에 대한 연구는 적다 5) difficulty in seperating "true" from "surrogate" risk factors

16. Clinical Application of Risk Factor Findings Scoring systems • to identify independent PONV risk factors + to develop formulas quantifying a given patient's likelihood of suffering nausea, emetic events, or both • only poor to moderate accuracy • 하지만 antiemetic intervention을 조정하는데 사용되어 PONV의 발생이 현격히 감소함 (특히, 고 위험군에서) • low risk patients에서 불필요한 비용과 side effects를 감소시킴

17. "gold standard"로 평가되는 scoring system은 아직 없음 • simplication and increased user-friendliness Apfel et al

18. Koivuranta et al. Elberhart et al. • 4-item simplified scoring system for children

19. Van den Bosch et al. • "semi-simplification »  • simplified scoring systems은 복잡한 계산과 상세한 history-taking을 방지할 수 있지만, more complex formulas에 비해 discriminating power는 동등하거나 더 좋다.

20. Clinical and Research Implication • modern multivariable risk factor studies는 PONV의 multifatorial nature에 대한 믿음을 강화시켰고 "multimodal approach"를 발전시켰다 - multimodal approach -> risk factor reduction + prophylaxis with antiemetics • "low", "moderate", "high", or "extremely high-risk" - low risk patients에서는 antiemetic prophylaxis가 cost-effective하지 않음 - moderate, high, extremely high-risk -> antiemetic prophylaxis (combination therapy), nonpharmacological intervention, multimodal management

21. Conclusions • Antiemetic prophylaxis와 multimodal management strategies를 위해서는 independent PONV risk factor에 대한 지식이 중요함 • Mordern multivariable studies, meta-analyses, systemic review는 지식을 증가시킴 • 현재 밝혀진 independent risk factors들은 PONV가 발생할 것 같은 환자를 예측하는데 사용 • 더 진행되고 있는 유전자 특성이나 outpatients, children에 대한 조사는 predictive system을 더욱 향상시킬 것이다 • 이러한 발전은 환자의 risk 정도를 더 잘 파악하게 해주고 PONV 발생을 감소시키며 PONV prophylaxis의 안전성과 cost-effectiveness를 향상시킬 것임