Clinical relevance of morphine-induced emesis and esophageal pH value in dogs during anesthesia

一、 研究目的 本實驗目的為調查犬隻嗎啡誘導嘔吐與麻醉下食道酸鹼值之關聯性。 二、 研究方法 研究對象為至臺灣大學生農學院附設動物醫院外科就診，因非腹腔手術而接受全身麻醉的犬隻病患，此外若罹患腸胃道疾病，以及持續服用已知會影響胃蠕動性、胃酸分泌能力或胃食道括約肌張力的藥物之病患，則不納入此研究。總共蒐集至少30隻犬隻病患作為實驗組，15隻犬隻病患為控制組。 實驗組為術前給藥計畫中包含嗎啡的犬隻，術前給藥不含嗎啡的犬隻病患納入控制組，但給藥計畫若包含其他嗎啡類藥物者，亦不納入控制組。嗎啡以肌肉注射途徑給予，劑量為0.5mg/kg。若在注射嗎啡後發生嘔吐，即量測及紀錄嘔吐物酸鹼值。病患在接受注射後至少十分鐘才能進入導入麻醉及插管，並於插管後經口放入食道酸鹼測量儀探頭量測食道酸鹼值，由麻醉醫師每五分鐘紀錄一次食道酸鹼值，直至麻醉結束。病歷記錄包括品種、體重、性別、年紀、鎮靜藥種類、propofol導入劑量、麻醉時間、術中及術後併發症。 三、 結果 共有47隻狗進入研究(實驗組31隻，控制組16隻)。實驗組中的31隻狗中有19例(61.3%)在給予嗎啡後十分鐘內發生嘔吐，此外，31隻狗中有16例(51.6%)在麻醉中發生胃食道逆流。其中發生嘔吐的19例中有10例(52.6%)發生胃食道逆流，未嘔吐的12例中有7例(58.3%)發生胃食道逆流。統計顯示嗎啡與嘔吐對於初始食道酸鹼值並無明顯的影響。嗎啡誘導嘔吐與性別、年紀、體重及鎮靜藥物亦無顯著關係，有關之風險因子只有品種。與控制組相比，術前給予嗎啡會顯著增加胃食道逆流的機率。 四、 結論 術前給予嗎啡無論是否引發嘔吐，均不會影響麻醉後食道之初始酸鹼值，顯示食道具有廓清酸性物質的能力。但術前給予嗎啡整體仍會增加胃食道逆流的機率，除此之外術前給予嗎啡在臨床上的短期副作用影響很小。Objective To investigate the relevance of morphine-induced emesis and esophageal pH in dogs undergoing non-abdominal surgery. Animals A total of 47 dogs, 6.1 ± 4.4 years old, and weighing 9.9 ± 8.9 kg. There were 31 dogs in the study group, and 16 dogs in the control group. Methods The study included dogs presenting to the National Taiwan University Veterinary Hospital for non-abdominal surgery. The premedication of the study group should included morphine (0.5mg/kg, I.M.). The control group had no morphine and other opioid analgesics in their anesthetic plan. The use of morphine was determined by the anesthetist based on patients’ clinical condition. All dogs were induced with propofol and maintained with isoflurane. Dogs with chronic gastrointestinal diseases or being persistently treated with drugs known to affect gastric motility, acid secretion and the tone of gastroesophageal sphincter were excluded. The pH of the vomitus and esophageal pH were measured with the esophageal pH meter and recorded by anesthetists during the anesthesia. Result In the study group, 19 of 31 dogs experienced vomiting after morphine premedication, and 16 of 31 dogs had gastroesophageal reflux during the anesthesia. 10 of 19 dogs with vomiting and 7 of 12 dogs without vomiting had subsequent gastroesophageal reflux. The administration of morphine and incidence of vomiting have no significant relevance with starting esophageal pH. The incidence of gastroesophageal reflux is significantly increased with the premedication of morphine comparing to the control group. Conclusion Morphine-induced emesis has no effect on starting esophageal pH suggests the good efficacy of acid clearance of esophagus. Administration of morphine is related to the increased incidence of gastoesophageal reflux. The adverse effect of morphine premedication could be ignored in short term observation