[每周一问]No.5 关于PONV
This week we'll be discussing one of the more frequent complications associated with anesthesia and surgery, postoperative nausea and vomiting. Today, we'll focus on the epidemiology of the problem.
1. Why should anesthesiologists be concerned about nausea and vomiting?
2. How common is PONV?
3. Can the definition of PONV affect its incidence?
4. What are the definitions of nausea, retching, and vomiting/emesis, and how are they different from one another?
本周我们讨论与麻醉和手术密切相关的经常发生的并发症之一—术后恶心与呕吐。今天，我们重点讨论该问题的流行病学。
1. 为什么麻醉科医生必须关注恶心与呕吐？
2. PONV发生率有多大？
3. PONV的定义是否影响其发病率？
4. 恶心、干呕、呕吐的定义是什么？他们之间相互的区别是什么？
[每周一问]No.5 关于PONV 参考答案
1.为什么麻醉科医生必须关注恶心与呕吐？
除了是最常发生的并发症之一，PONV也是导致术后住院时间延长到最有力的预测因素。此外，PONV的症状很痛苦，并且可能成为手术切口裂开的潜在危险因素，比如眼睛手术或矫形外科手术。PONV可能导致胃内容物反流入口腔，特别是在半清醒患者容易发生误吸。最后，虽然很少出现死亡，但是有因为呕吐直接导致死亡的报道，是因为食管破裂、气胸、脾破裂、血肿形成以及伤口裂开所致。
2.PONV发生率有多大？
过去60年的大宗病例报道中PONV的发生率为20~30%，主要是因为外科与患者的因素（本月晚些时间讨论）。然而，在特定情况及特定病人中（比如小儿斜视矫治手术），发生率达到80%甚至更高。
3.PONV的定义是否影响其发病率？
PONV的严重程度界限与症状的持续时间可较大的影响其发生率，大多数学者认为PONV的定义应该包括术后最初24小时的情况。Carrol等研究发现，接受门诊手术的病人中大约35%出现术后PONV，症状平均持续7天以上。
此外，虽然恶心欲呕吐经常被认为同一现象的一部分，但是他们并非必须同时出现，治疗某一症状的药物也未必缓解另一症状。即使如此，当他们正常出现时(在本周讨论中)，被认为是一个整体。
4.恶心、干呕、呕吐的定义是什么？他们之间相互的区别是什么？
恶心指与呕吐冲动相关的一种主观不适感。
干呕是指包括膈肌、胸壁、腹壁在内的呼吸相关的肌肉节律性的、费力地痉挛性收缩，但不会排出胃内容物。
呕吐指胃内容物从口腔迅速排出，是由于腹壁肌肉的强有力的持续收缩、膈肌下降以及胃贲门口的开放导致的结果。
[每周一问]No.5 关于PONV 参考答案
Why should anesthesiologists be concerned about nausea and vomiting?
In addition to being one of the most frequent complications, postoperative nausea and vomiting (PONV) remains among the strongest predictors of protracted postoperative stays and hospital admissions (1). In addition, the symptoms of PONV are distressing and may be potentially disruptive to the operative result, such as with ocular or plastic surgery. Moreover, with the introduction of gastric contents into the oropharynx, especially in a partially sedated patient, aspiration may occur. Finally, although rare, deaths as a direct result of vomiting have been reported, as a result of esophageal rupture, pneumothorax, splenic laceration, hematoma formation, and wound dehiscence (2).
How common is PONV?
The overall incidence of PONV in large group studies conducted over the past 6 decades varies between 20-30%, depending on a number of surgical and patient factors (to be discussed later this week) (3). However, in certain procedure and patient combinations (i.e. strabismus surgery in children), the incidence can be 80% or higher (4).
Can the definition of PONV affect its incidence?
The severity threshold and the duration of the symptoms recorded may profoundly affect the incidence of PONV reported. For instance, while most investigators accept that the definition of PONV extends to include evaluation for the first 24 hours postoperatively (2), postdischarge PONV can be a frequent occurrence. Carrol et al. (5) noted that 35% of patients undergoing outpatient procedures experienced postdischarge PONV, with symptoms lasting on average up to 7 days.
In addition, although nausea and vomiting are often considered as part of the same phenomenon, they do not necessarily accompany each other nor do drugs which prevent one symptom necessarily allay the other. Nonetheless, as they are commonly presented together in the literature, during this week, they will be considered as one entity.
What are the definitions of nausea, retching, and vomiting/emesis, and how are they different from one another?
Nausea is defined as a subjectively unpleasant sensation associated with an awareness of the urge to vomit (3). Retching is defined as labored, spasmodic, rhythmic contractions of the respiratory muscles including the diaphragm, chest wall, and abdominal wall without the expulsion of gastric contents . Vomiting or emesis, is defined as the forceful expulsion of gastric contents from the oral cavity and is accomplished by powerful sustained contractions of the abdominal muscles, descent of the diaphragm, and opening of the gastric cardia .
Question Author: Lawrence Tsen, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School
References:
1. Megerian CA, Reily J, O'Connell FM, Heard SO. Outpatient Tympanomastoidectomy: Factors Affecting Hospital Admission. Arch Otolaryngol Head Neck Surg. 2000;126(11):1345-8.
2. McGoldrick KE. Postoperative nausea and vomiting. Probl Anesth 2000;12:274-86.
3. Watcha MF, White PF. Postoperative nausea and vomiting. Its etiology, treatment, and prevention. Anesthesiology. 1992;77(1):162-84.
4. Sadhasivam S, Shende D, Madan R. Prophylactic ondansetron in prevention of postoperative nausea and vomiting following pediatric strabismus surgery: a dose-response study. Anesthesiology 2000;92(4):1035-42.
5. Carroll NV, Miederhoff P, Cox FM, Hirsch JD. Postoperative nausea and vomiting after discharge from outpatient surgery centers. Anesth Analg. 1995;80(5):903-9.
6. Seigal LJ, Longo DL. The control of chemotherapy induced emesis. Ann Intern Med 1981;95:352-9.
