Electrophysiological evaluation of phrenic nerve injury during cardiac surgery--a prospective, controlled, clinical study.
BACKGROUND
According to some reports, left hemidiaphragmatic paralysis due to phrenic nerve injury may occur following cardiac surgery. The purpose of this study was to document the effects on phrenic nerve injury of whole body hypothermia, use of ice-slush around the heart and mammary artery harvesting.


METHODS
Electrophysiology of phrenic nerves was studied bilaterally in 78 subjects before and three weeks after cardiac or peripheral vascular surgery. In 49 patients, coronary artery bypass grafting (CABG) and heart valve replacement with moderate hypothermic (mean 28 degrees C) cardiopulmonary bypass (CPB) were performed. In the other 29, CABG with beating heart was performed, or, in several cases, peripheral vascular surgery with normothermia.


RESULTS
In all patients, measurements of bilateral phrenic nerve function were within normal limits before surgery. Three weeks after surgery, left phrenic nerve function was absent in five patients in the CPB and hypothermia group (3 in CABG and 2 in valve replacement). No phrenic nerve dysfunction was observed after surgery in the CABG with beating heart (no CPB) or the peripheral vascular groups. Except in the five patients with left phrenic nerve paralysis, mean phrenic nerve conduction latency time (ms) and amplitude (mV) did not differ statistically before and after surgery in either group (p > 0.05).


CONCLUSIONS
Our results indicate that CPB with hypothermia and local ice-slush application around the heart play a role in phrenic nerve injury following cardiac surgery. Furthermore, phrenic nerve injury during cardiac surgery occurred in 10.2 % of our patients (CABG with CPB plus valve surgery).
Canbaz
Suat
S
Department of Cardiovascular Surgery, Trakya University, Medical Faculty, Edirne, Turkey. scanbaz2001@yahoo.com
Turgut
Nilda
N
Halici
Umit
U
Balci
Kemal
K
Ege
Turan
T
Duran
Enver
E
D000704:Analysis of Variance; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004594:Electrophysiology; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000601:surgery; D010791:Phrenic Nerve / Q000293:injuries / Q000502:physiology*; D011446:Prospective Studies; D012133:Respiratory Paralysis / Q000209:etiology* / Q000503:physiopathology