PURPOSE: CPB for cardiac surgery has been implicated in causing atelectasis which is a major cause of intrapulmonary shunting and hypoxemia postoperatively. Total vital capacity maneuver (TVCM) performed before termination of the surgery reduces significantly intrapulmonary shunt but the benefit is rapidly lost in less than 4 hours. The study aimed to test if the repetition of RM for the lungs before and after extubation can reduce intrapulmonary shunt for a longer period after extubation (24 hours).
METHODS: Forty patients scheduled for cardiac valve replacement surgery were randomized to receive one of two strategies. The treatment group (T) received TVCM at the end of surgery before closing the sternum repeated each 4 hours till extubation. Then intermittent positive pressure breathing (IPPB) was applied by a facial mask at a pressure of 30 cm H2O each 4 hours. Control group (C) received standard care with an incentive spirometer each 4 hours after extubation. Intrapulmonary shunts (Qs/Qt), systemic and central hemodynamics were measured after induction of anesthesia, at the end of surgery and every 4 hours till 24 hours after extubation. Duration of postoperative intubation was recorded. Lung function was measured every 12 hours till discharge.
RESULTS: No significant difference in Qs/Qt existed in ANOVA study between the 2 groups at 24 hours after extubation (5.3±2.4% and 4.5±3.3% respectively). At the end of surgery, Qs/Qt increased in T group (7.3±3.2% to 13.5±3.7%; p< 10–3) was significantly less (p0.02) compared to C group (7.3±3.7% to 16.1±6%; p <10–3). Time to extubation was in T group (8.8±4.2 hours) compared to C group (10.4±4.3 hours) (p 0.2 ns). No significant difference in vital capacity decreased in the T group (3.17±1.2 to 1.9±1 liter) compared to C group (3.4±0.8 to 2.1±0.9 liter).
CONCLUSION: Repetitive RM each 4 hours after CPB applied after surgery, before and after extubation, do not assure a sustained benefit on intrapulmonary shunt.
CLINICAL IMPLICATIONS: Repetitive RM is beneficial in the short post surgery period only.
DISCLOSURE: Moussa Riachy, None.