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Phrenic nerve function and its relationship to atelectasis after coronary artery bypass surgery
1University of British Columbia Pulmonary Research Laboratory, St. Paul's Hospital, Vancouver, Canada.
Chest
|April 1, 1988
Summary
Postoperative atelectasis after coronary artery bypass surgery (CAB) is common. While phrenic nerve injury can occur, other factors likely contribute more significantly to widespread atelectasis in CAB patients.
Area of Science:
- Cardiovascular Surgery
- Thoracic Surgery
- Pulmonary Medicine
Background:
- Atelectasis is a frequent complication following coronary artery bypass surgery (CAB).
- The role of operative variables and phrenic nerve injury in its development requires further investigation.
Purpose of the Study:
- To assess the impact of intraoperative factors on postoperative atelectasis after CAB.
- To determine the incidence of phrenic nerve injury associated with topical cold cardioplegia during CAB.
Main Methods:
- Studied 57 patients undergoing CAB, evaluating phrenic nerve function using transcutaneous stimulation in 52 patients.
- Utilized discriminant analysis to identify intraoperative variables associated with atelectasis severity.
- Assessed phrenic nerve function preoperatively and postoperatively.
Main Results:
- Phrenic nerve paresis was documented in 5 patients; reduced diaphragm action potential in 27 others, though causality was limited.
- More severe atelectasis correlated with a higher number of grafts, longer operative/bypass times, pleural space entry, and lower body temperature.
- Lack of a right atrial drain and cardiac insulating pad also linked to increased atelectasis.
Conclusions:
- Phrenic nerve paresis can occur after CAB and topical cold cardioplegia.
- However, factors beyond phrenic nerve injury are primarily responsible for the high incidence of atelectasis in CAB patients.