Recovery after Unilateral Phrenic Injury Associated with Coronary Artery Revascularization: Results (2)

Recovery after Unilateral Phrenic Injury Associated with Coronary Artery Revascularization: Results (2)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)
Left Right Left Right
Patient 1
150 13.7 9.2 127 363
240 11.3 7.9 163 382
290 10.4 7.9 254 320
570 7.9 7.8 500 454
Patient 2
20 10.0 409
63 9.5 400
132 9.8 350
380 12.9 9.9 380 370
Patient 3
60 8.3 182
184 13.7 8.3 145 254
264 10.0 7.9 282 263
440 9.6 7.9 418 436
Patient 4
60 6.7 290
110 6.3 363
215 10.4 6.3 345 372
490 8.7 6.3 381 409
Patient 5
9 7.9 400
40 7.9 409
140 7.7 522
415 10.0 7.5 209 454
500 10.8 7.1 290 309

Figure-1

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.

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