Diaphragmatic plication in adult patients with diaphragm paralysis after cardiac surgery.
OBJECTIVE: We investigated the benefit of diaphragmatic plication for weaning from mechanical ventilation in these adult patients. PATIENTS AND METHODS: Four patients underwent diaphragmatic plication for difficulty of weaning from mechanical ventilation due to diaphragmatic paralysis. They were all men with an average age of 70.5 +/- 6.3 years. Three of the patients had undergone cardiac surgeries for coronary artery bypass grafting and one patient ascending aortic replacement for pseudoaneurysm after coronary revascularization. Right diaphragmatic plication (muscle sparing procedure) was performed between 30 to 61 days after cardiac surgery. RESULTS: The mean forced tidal volume improved dramatically from 216 to 415 ml after plication in all patients, and it was possible to discontinue mechanical ventilation from 2 to 12 days after plication. One patient with obstructive respiratory dysfunction died from aspiration pneumonia 15 days after plication. However, postoperative tidal volume in this patient improved to 420 ml and he was able to be weaned from ventilatory support five days after plication. The other three patients were discharged between 26 to 58 days after plication and continue to do well without symptoms. CONCLUSION: Diaphragmatic plication is a useful procedure for treatment of diaphragmatic paralysis in adults as well in children. (+info)
Ventilatory response to hypoxia in experimental pathology of the diaphragm.
In this study, we examined the usefulness of arterial blood gas variables, as changed by the hypoxic stimulus, in discerning various experimentally-induced conditions of diaphragm weakness in anesthetized cats. We defined three experimental situations (models): (i) intact muscle, statistical Class I, (ii) four degrees of muscle dysfunction (after sequential diaphragm denervation), Classes II-V, and (iii) entirely paralyzed muscle, Class VI. Responses to a hypoxic stimulus in the above-mentioned conditions were evaluated by using the methods of the pattern recognition theory. We found that before the hypoxic stimulus, with partial but of different severity denervation of the diaphragm, the k-nearest neighbor classifier (k-NN) assigned 100% of the classified cases to Class II (one phrenic nerve rootlet cut). In contrast, during hypoxia only 67% of cases were assigned to Class II, the remaining being spread throughout other classes of muscle weakness. When one limits the procedure to the extreme classes: Class I (intact diaphragm) and Class VI (totally denervated diaphragm), the k-NN picks out 33% and 50% cases of bilateral diaphragm paralysis before and during hypoxia, respectively. We conclude that any remaining innervations of the diaphragm ensure the functionally optimal level of lung ventilation that may waver when hypoxia develops. (+info)
Uneven distribution of ventilation in acute respiratory distress syndrome.
INTRODUCTION: The aim of this study was to assess the volume of gas being poorly ventilated or non-ventilated within the lungs of patients treated with mechanical ventilation and suffering from acute respiratory distress syndrome (ARDS). METHODS: A prospective, descriptive study was performed of 25 sedated and paralysed ARDS patients, mechanically ventilated with a positive end-expiratory pressure (PEEP) of 5 cmH2O in a multidisciplinary intensive care unit of a tertiary university hospital. The volume of poorly ventilated or non-ventilated gas was assumed to correspond to a difference between the ventilated gas volume, determined as the end-expiratory lung volume by rebreathing of sulphur hexafluoride (EELVSF6), and the total gas volume, calculated from computed tomography images in the end-expiratory position (EELVCT). The methods used were validated by similar measurements in 20 healthy subjects in whom no poorly ventilated or non-ventilated gas is expected to be found. RESULTS: EELVSF6 was 66% of EELVCT, corresponding to a mean difference of 0.71 litre. EELVSF6 and EELVCT were significantly correlated (r2 = 0.72; P < 0.001). In the healthy subjects, the two methods yielded almost identical results. CONCLUSION: About one-third of the total pulmonary gas volume seems poorly ventilated or non-ventilated in sedated and paralysed ARDS patients when mechanically ventilated with a PEEP of 5 cmH2O. Uneven distribution of ventilation due to airway closure and/or obstruction is likely to be involved. (+info)
Unilateral diaphragmatic paralysis: an electrophysiological study.
An electrophysiological study was carried out on four patients with unilateral diaphragmatic paralysis. Whereas neurogenic involvement of the paralysed hemidiaphragm was roughly similar in all cases, neurogenic patterns could be detected in the normally moving contralateral hemidiaphragm in three cases, and the degree of involvement could be correlated with the respiratory state of the patients. EMG also showed that the neuropathic process affected the limb muscles. Thus unilateral diaphragmatic paralysis may be, at least in some cases, the localised expression of a more diffuse neuropathy, perhaps a peculiar form of neuralgic amyotrophy. (+info)
A pattern recognition method to distinguish gradual unilateral diaphragm paralysis in the cat.
This work deals with the application of a pattern recognition method to distinguish the degree of diaphragm paralysis after gradual unilateral sections of phrenic nerve rootlets in anesthetized, spontaneously breathing cats. The data set consisted of the features that characterize breathing pattern and of phrenic nerve amplitude. The method called for stratification of 6-dimensional vectors into three classes: intact, partial, and complete unilateral phrenicotomy, which offers the possibility to construe the classification rule on the basis of the information contained in a set of feature vectors with the known class-membership. This method deals with the use of a distance function as a measure of similarity between two feature points. The results show that the degree of diaphragm paralysis could be recognized with the probability higher than 90%. Distinguishing the severity of diaphragmatic dysfunction and the compensatory strategies of the respiratory system, knowing only a handful of basic values describing breathing pattern, might have a practical meaning in respiratory emergencies. (+info)
The effect of intermittent positive pressure breathing on lung volumes in acute quadriparesis.
Resting tidal volume and vital capacity were measured daily in 5 patients with acute quadriparesis during the first 7 to 10 days of their hospitalisation. On admission, vital capacity was significantly reduced to 26% of the predicted value (p less than 0.001). This increased significantly over the study period to 33% of the predicted value (p less than 0.02). Expiratory flow rates, measured on one occasion during the study period, showed similar decrements. Tidal volume and vital capacity were also measured immediately following administration of intermittent positive pressure breathing (IPPB). Although the lung volume achieved during IPPB was significantly higher than resting values of tidal volume and vital capacity (p less than 0.001), tidal volume returned to baseline values as soon as IPPB was ceased. Vital capacity remained significantly higher than baseline values at this stage (p less than 0.02), although the mean increase in vital capacity immediately following IPPB was only 43 mls. Acute quadriparesis is associated with a severe ventilatory impairment which includes a reduced vital capacity and expiratory flow rates. IPPB has a positive effect on lung volume whilst it is being administered. Immediately following treatment, this effect does not appear to be sustained at a level which would be considered clinically significant. (+info)
Ventilatory failure and successful management for a dog with severe cervical meningioma.
A 12-year-old intact male mongrel dog with a weight of 22 kg was referred with a complaint of progressive tetraparesis. Cervical myelography revealed an intradural-extramedullary mass at the second cervical vertebra. After computed tomography (CT) under general anesthesia, the patient showed dyspnea and cyanosis caused by insufficient movement of the chest wall. Positive pressure ventilation was therefore initiated. Hemilaminectomy and partial mass removal were performed 12 hr after the CT. The mass was histopathologically diagnosed as meningioma. Gradual weaning from the mechanical ventilation lasted for 80 hr after the operation. The patient eventually recovered from the ventilatory failure and the tetraparesis at approximately 6 and 14 days after the operation, respectively. (+info)
The physiological challenges of the 1952 Copenhagen poliomyelitis epidemic and a renaissance in clinical respiratory physiology.
The 1952 Copenhagen poliomyelitis epidemic provided extraordinary challenges in applied physiology. Over 300 patients developed respiratory paralysis within a few weeks, and the ventilator facilities at the infectious disease hospital were completely overwhelmed. The heroic solution was to call upon 200 medical students to provide round-the-clock manual ventilation using a rubber bag attached to a tracheostomy tube. Some patients were ventilated in this way for several weeks. A second challenge was to understand the gas exchange and acid-base status of these patients. At the onset of the epidemic, the only measurement routinely available in the hospital was the carbon dioxide concentration in the blood, and the high values were initially misinterpreted as a mysterious "alkalosis." However, pH measurements were quickly instituted, the Pco(2) was shown to be high, and modern clinical respiratory acid-base physiology was born. Taking a broader view, the problems highlighted by the epidemic underscored the gap between recent advances made by physiologists and their application to the clinical environment. However, the 1950s ushered in a renaissance in clinical respiratory physiology. In 1950 the coverage of respiratory physiology in textbooks was often woefully inadequate, but the decade saw major advances in topics such as mechanics and gas exchange. An important development was the translation of the new knowledge from departments of physiology to the clinical setting. In many respects, this period was therefore the beginning of modern clinical respiratory physiology. (+info)