Phrenic nerve and diaphragm function following open heart surgery: a prospective study with and without topical hypothermia.
In a prospective study, 100 patients undergoing open heart surgery were randomly allocated to receive ice/slush topical hypothermia for myocardial protection (Group I, n = 56) or not (Group II, n = 44). Chest radiographs, diaphragm screening, lung function and phrenic nerve conduction time were assessed pre-operatively and at 1 week and 1 month post-operatively in all patients and subsequently at 3 months, 6 months, 1 year and 2 years in all patients with radiological evidence of diaphragm paralysis. The two groups were similar in terms of age, sex, diabetes and smoking habits. Cardiopulmonary bypass and aortic cross-clamp times were similar in the two groups. Radiological evidence of partial left lower lobe collapse was more frequent in Group I (79 per cent vs. 36 per cent, p < 0.01). Twenty (36 per cent) Group I patients developed unilateral diaphragm paralysis (19 left-sided) compared with none in Group II. Diaphragm paralysis was still present in 19 patients (34 per cent) at 1 month, in five patients (9 per cent) at 1 year and in one patient (2 per cent) at 2 years post-operatively. Phrenic nerve conduction time was recorded in 98 per cent of patients pre-operatively, but was unrecordable on the appropriate side in all 20 patients with diaphragm paralysis 1 week post-operatively. Prolonged phrenic nerve conduction time on the left side was found in a further seven Group I patients 1 week post-operatively. There were no significant differences between the two groups in terms of post-operative arrhythmias, myocardial infarction or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)
Efthimiou
J
J
John Radcliffe Hospital, Headington, Oxford.
Butler
J
J
Woodham
C
C
Westaby
S
S
Benson
M K
MK
D000368:Aged; D006348:Cardiac Surgical Procedures / Q000379:methods*; D002315:Cardiopulmonary Bypass; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010791:Phrenic Nerve / Q000293:injuries* / Q000503:physiopathology; D011446:Prospective Studies; D012133:Respiratory Paralysis / Q000209:etiology* / Q000503:physiopathology; D014797:Vital Capacity / Q000502:physiology