Diaphragmatic paralysis: the use of M mode ultrasound for diagnosis in adults

Study Design: Retrospective, case series. Objectives: To evaluate the use of M mode ultrasonography in the evaluation of diaphragmatic paralysis in adults. Setting: Radiology department, Princess Alexandra Hospital, Brisbane, Australia. Methods: Ten patients who were referred for evaluation of suspected diaphragmatic paralysis were evaluated using M mode ultrasound. Results: Three of the patients who were scanned demonstrated normal diaphragmatic movement. The M mode trace demonstrated normal movement of the diaphragm bilaterally with quiet respiration and a sharp upstroke on the sniff test (indicating normal caudal movement of the diaphragm). Six patients were found to have a unilateral diaphragmatic paralysis. Four of these patients were noted to have a raised hemi-diaphragm on chest radiography. Of the two who did not have a raised hemi-diaphragm on chest radiography, one was permanently ventilated. The M mode trace of the paralyzed side showed no active caudal movement of the diaphragm with inspiration and abnormal paradoxical movement (ie cranial movement on inspiration) particularly with the sniff test. Conclusion: M mode ultrasonography is a relatively simple and accurate test for diagnosing paralysis of the diaphragm, in the adult population. It can be performed, if necessary, at the bedside and can be easily repeated if paralysis is not thought to be permanent. Equipment: Philips ATL Sono CT 5000 using a 2-5MHz curved linear transducer.