Effects of different head-down tilt angles on respiratory mechanics and cerebral circulation during laparoscopic radical resection of rectal carcinoma / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of different head-down tilt (HDT) angles on respiratory mechanics and cerebral circulation during laparoscopic radical resection of rectal carcinoma in the patients.Methods Thirty patients of both sexes,aged 40-64 yr,of ASA physical status Ⅰ or Ⅱ,with body mass index ＜ 30 kg/m2,scheduled for elective laparoscopic radical resection of rectal carcinoma,were included in the study.Anesthesia was induced with midazolam,fentanyl,propofol and cis-atracurium and maintained with targetcontrolled infusion of propofol and remifentanil and cis-atracurium when needed.At 5 min after supine position,5 min after 30° HDT,5 min after 35° HDT,5 min after 40° HDT,and 30 min after pneumoperitoneum (T1-5),airway pressure (Paw),peak airway pressure (PIP),lung compliance (Cpat) and jugular bulb blood pressure (JBP) were recorded.Blood samples were taken from the radial artery and jugular bulb for blood gas analysis and arterial partial pressure of oxygen (PaO2),partial pressure of carbon dioxide in artery (PaCO2),arterial oxygen saturation (SaO2),jugular bulb oxygen partial pressure (PjvO2),and jugular bulb venous saturation (SjvO2) were recorded at each time point mentioned above.Results Paw,PIP,MAP,PaCO2,JBP,PjvO2 and SjvO2 were significantly increased as compared with those obtained when the patients were in supine position,increased gradually with the increasing HDT angles,and decreased to the level obtained when the patients were in supine position at 30 min after pneumoperitoneum.Cpat and PaO2 were significantly decreased as compared with those obtained when the patients were in supine position decreased gradually with the decreasing HDT angles,and increased to the level obtained when the patients were in supine position at 30 min after pneumoperitoneum.Conclusion HDT-induced effects on respiratory mechanics and cerebral circulation increase with increasing angles during laparoscopic radical resection of rectal carcinoma; thus the optimum HDT angle is smaller than 40° for the patients undergoing this kind of surgery.