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

Recovery after Unilateral Phrenic Injury Associated with Coronary Artery Revascularization: Methods (2)The phrenic nerves were studied by measuring latency and the CDAP after transcutaneous supramaximal phrenic nerve stimulation. The diaphragm response was measured with two surface disc electrodes, one placed over the xiphoid process of the sternum and the other over the ipsilateral seventh intercostal space at the costochondral junction. The parameters measured were the time from stimulus to onset of diaphragmatic EMC activity (latency of conduction) and the amplitude of the CDAP (from baseline to peak of the EM Cl deflection). Reference values for latency were taken from Markand et al” with an upper limit of normal selected as 9.75 ms. Sniff testing also was performed to evaluate diaphragmatic function in all patients. The fluoroscopic excursion of the hemidiaphragm was evaluated by a radiologist unaware of the study protocol during a sudden sniff maneuver from FRC with the patient in the standing position. A paradoxic movement of the hemidiaphragm was interpreted as being suggestive of diaphragmatic paralysis.
All these studies were repeated subsequently at intervals to assess recover) after surgery. buy asthma inhaler
Autopsy studies were performed on 12 patients to estimate the distance over which the phrenic nerve regenerates. Assuming an injury occurred over the mid-pericardium, the length of the left phrenic nerve to its point of entry into the crus of the hemidiaphragm was 14.8 ±0.84 cm (mean ± SD).

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