Time-cycled inverse ratio ventilation does not improve gas exchange during anaesthesia

Abstract

Time-cycled inverse ratio ventilation does not improve gas exchange during anaesthesiaInverse ratio ventilation (IRV)

Prolonged inspiratory time produces better gas exchange in patients undergoing laparoscopic surgery: A randomised trial

“…Prolonged inspiratory time is beneficial only when a significant amount of recruitable lung units exist. This could be the reason why previous studies failed to show or showed marginal effects of IRV in subjects under general anaesthesia . However, pneumoperitoneum in the Trendelenburg position causes a cephalad shift of the diaphragm and closure of small airways, considerably increasing the number of recruitable lung units .…”

“…There are previous reports of applying IRV during general anaesthesia . Tweed and Lee investigated the effect of IRV during orthopaedic surgery under general anaesthesia and found that increasing Pmean by time‐cycled IRV has no beneficial effect on pulmonary mechanics or gas exchange . They also applied pressure‐controlled IRV in patients undergoing lower abdominal gynaecologic surgery in the Trendelenburg position.…”

“…Previous studies reported that pressure‐controlled inverse ratio ventilation (IRV) with an inspiratory‐to‐expiratory ratio (I : E ratio) of 2 : 1 is more effective for gas exchange than volume‐controlled conventional ratio ventilation (I : E ratio of 1 : 2) in patients with acute respiratory distress syndrome . Several studies evaluated the effects of IRV during general anaesthesia and found no or minimal improvement of gas exchange, and improvement of alveolar‐arterial oxygen differences . However, there have been no studies applying IRV in subjects undergoing pelvic laparoscopic surgery in the Trendelenburg position.…”

The effects of prolonged inspiratory time during one‐lung ventilation: a randomised controlled trial

“…There have been reports of using IRV during general anaesthesia. Whilst IRV had no beneficial effects when patients were placed in the supine position , arterial oxygenation increased slightly when patients were placed in the Trendelenburg position . Another study reported that IRV reduced intra‐operative A‐aDO 2 .…”

“…Inverse‐ratio ventilation is a prolonged inspiratory time compared with expiratory time and is known to be effective for increasing oxygenation and reducing peak airway pressures in adults with respiratory distress syndrome and respiratory failure . Previous studies evaluating the effect of IRV during general anaesthesia revealed no muscle‐sparing or only a marginal improvement in gas exchange ; however, there have been no studies investigating the effectiveness of IRV in subjects undergoing OLV for lung surgery. The aim of our study was to evaluate whether a prolonged inspiratory time improves gas exchange and respiratory mechanics in patients undergoing lung surgery with OLV compared with conventional ventilatory settings.…”