An elevated left hemidiaphragm and partial left lower lobe atelectasis were noted in all patients on postoperative day 3 and discharge chest radiographs (Table 1). Paradoxic movement of the left hemidiaphragm was seen fluoroscopically during sniff maneuvers in all patients on the initial study. Left phrenic paralysis was confirmed in four patients by absence of an electromyographic response to left phrenic nerve stimulation when first evaluated postoperatively (days 9, 20, 60 and 60) (Table 2). In the other patient (patient 1), the left phrenic nerve latency was prolonged and the CDAP amplitude reduced when first studied (postoperative day 150), indicative of a paresis of the left phrenic nerve.
Paralysis of the right phrenic nerve was not detected in any patient. A right phrenic nerve paresis was suggested, however, in two patients in the initial study. The right phrenic nerve latency was slightly prolonged in patient 2 20 days postoperatively. In patient 1, there was a subsequent decrease in right phrenic nerve latency of 1.3 ms, even though the initial latency was within the reported normal range. flovent inhaler
Inspiratory muscle weakness was noted in all five patients when first studied after surgery (Fig 1). A recovery in inspiratory muscle strength occurred in all patients on subsequent testing. In two patients (No. 3 and 4), the most marked increases in Pi max coincided with the restoration of a diaphragmatic EMG response to phrenic nerve stimulation. At the time of final study, Pi max had returned to normal in the three patients whose phrenic nerve latency was less than 10 ms. Inspiratory muscle weakness persisted, however, in the two patients with abnormal latencies at 380 and 500 days postoperatively.
Table 1—Data on Five Patients Undergoing CAB Surgery
|Duration of Ventilation(Days)||Chest X-ray Findings|
|PatientNo.||Age, (yr)||CAB Graft||Use of Cardioplegia||Cross Clamp Time (min)||Preoperative||Postoperative Day 3|
|1||66||2 vein grafts, left internal mammary||Yes||70||5||Normal||Elevated left hemidiaphragm, left lower lobe atelectasis|
|2||65||3 vein grafts, left internal mammary||Yes||92||1||Normal||Elevated left hemidiaphragm|
|3||61||3 vein grafts, left internal mammary||Yes||62||0.5||Normal||Left pleural effusion, left lower lobe atelectasis & consolidation, elevated left hemidiaphragm|
|4||53||3 vein grafts, left internal mammary||Yes||55||1||Normal||Elevated left hemidiaphragm, left lower lobe atelectasis|
|5||70||3 vein grafts||Yes||80||2.5||Normal||Left pleural effusion, left lower lobe atelectasis, elevated left hemidiaphragm|
Table 2—Serial Phrenic Nerve Studies in Five Patients with Phrenic Nerve Paresis/Paralysis after CAB Surgery
|PostoperativeDay||Phrenic Nerve Latency s||Phrenic Nerve Amplitude (|JiV)|
Figure 1. Sequential measurements of Pimax (top graph), Pnmax (center graph) and FVC (bottom graph), after CAB surgery in five patients. Each patient is represented by a separate symbol.