Determinants of diaphragm motion in unilateral diaphragmatic paralysis.
Cranial displacement of a hemidiaphragm during sniffs is a cardinal sign of unilateral diaphragmatic paralysis in clinical practice. However, we have recently observed that isolated stimulation of one phrenic nerve in dogs causes the contralateral (inactive) hemidiaphragm to move caudally. In the present study, therefore, we tested the idea that, in unilateral diaphragmatic paralysis, the pattern of inspiratory muscle contraction plays a major role in determining the motion of the inactive hemidiaphragm. We induced a hemidiaphragmatic paralysis in six anesthetized dogs and assessed the contour of the diaphragm during isolated unilateral phrenic nerve stimulation and during spontaneous inspiratory efforts. Whereas the inactive hemidiaphragm moved caudally in the first instance, it moved cranially in the second. The parasternal intercostal muscles were then severed to reduce the contribution of the rib cage muscles to inspiratory efforts and to enhance the force generated by the intact hemidiaphragm. Although the change in pleural pressure (DeltaPpl) was unaltered, the cranial displacement of the paralyzed hemidiaphragm was consistently reduced. A pneumothorax was finally induced to eliminate DeltaPpl during unilateral phrenic nerve stimulation, and this enhanced the caudal displacement of the inactive hemidiaphragm. These observations indicate that, in unilateral diaphragmatic paralysis, the motion of the inactive hemidiaphragm is largely determined by the balance between the force related to DeltaPpl and the force generated by the intact hemidiaphragm. (+info)
Negative extrathoracic pressure ventilation for phrenic nerve palsy after paediatric cardiac surgery.
OBJECTIVE: To investigate the feasibility of negative extrathoracic pressure ventilation as a respiratory support following phrenic nerve palsy after cardiac surgery. DESIGN: An uncontrolled pilot study. PATIENTS: 14 patients aged one week to 30 months (median 5.3 months) with phrenic nerve palsy diagnosed by phrenic nerve conduction tests and diaphragmatic electromyograms. Four had bilateral and 10 unilateral palsy. Before treatment all required oxygen and 10 were receiving positive pressure ventilation. One of the patients with bilateral and four of the patients with unilateral palsies had undergone a plication before negative pressure ventilation was started. INTERVENTION: Treatment was started 6-65 days (median 23) after operation with a newly designed system which included a Perspex chamber, which gave easy access to the child, and an elastic latex neck seal. Continuous negative pressure was used in conjunction with intermittent positive pressure ventilation while continuous or intermittent negative pressure ventilation was used in extubated infants. RESULTS: All four patients with bilateral palsy survived with long-term intermittent negative pressure ventilation and did not require further surgery. Of the 10 with unilateral lesions, seven required no further surgery, two underwent plication, and one had a re-plication. Three patients with unilateral palsy died of non-respiratory causes. The duration of positive pressure ventilation after starting negative pressure ranged from 0 to 23 days (median 6). Treatment with negative pressure lasted for 3-241 days (median 32) and was predominantly administered off the intensive care unit, including at home. CONCLUSIONS: Negative pressure ventilation may be an alternative to positive airway pressure ventilation in the management of phrenic nerve palsy. A multicentre randomised controlled trial is now required to assess further the role of negative pressure ventilation in phrenic nerve palsy. (+info)
Severe infantile neuropathy with diaphragmatic weakness and its relationship to SMARD1.
A group of 13 patients with early onset diaphragmatic palsy in association with a progressive neuropathy is presented. All eight of those tested were found to have mutations in the same gene encoding the immunoglobulin mu-binding protein 2 (IGHMBP2) in patients with spinal muscular atrophy (SMA) with respiratory distress type 1. Six out of these eight patients had either homozygous or compound heterozygous mutations, and two had only a single heterozygous mutation. Detailed analysis of the clinical picture and the neurophysiological and histopathological findings indicated that these patients shared similar characteristics, which were further developed as a set of diagnostic criteria. Some of the most striking of these were early onset of respiratory compromise, a markedly low birth weight, very slow motor nerve conduction velocities and a general decrease in the size of myelinated fibres on sural nerve biopsy. Extensive histological examination of the spinal cord in one patient failed to find any evidence of an SMA. Four out of the five not tested genetically were positive for all diagnostic criteria. None of the cases of early onset neuropathies or spinal muscular atrophies with early respiratory failure reviewed in the literature shares the exact characteristics, but many do have very close similarities. Their classification varies, but the discovery of mutations in IGHMBP2 in cases that are variously classified as SMA plus or severe infantile neuropathy with respiratory distress points to a need for the search for this genetic defect to be widened to include both groups. The fact that we identified other, similar cases of neuropathy and early respiratory failure with and without IGHMBP2 mutations suggests genetic as well as clinical heterogeneity in these infants. It is possible that infants that do not have mutations in the IGHMBP2 gene will be found to have mutations in a similar functioning gene. (+info)
Electrophysiological evaluation of phrenic nerve injury during cardiac surgery--a prospective, controlled, clinical study.
BACKGROUND: According to some reports, left hemidiaphragmatic paralysis due to phrenic nerve injury may occur following cardiac surgery. The purpose of this study was to document the effects on phrenic nerve injury of whole body hypothermia, use of ice-slush around the heart and mammary artery harvesting. METHODS: Electrophysiology of phrenic nerves was studied bilaterally in 78 subjects before and three weeks after cardiac or peripheral vascular surgery. In 49 patients, coronary artery bypass grafting (CABG) and heart valve replacement with moderate hypothermic (mean 28 degrees C) cardiopulmonary bypass (CPB) were performed. In the other 29, CABG with beating heart was performed, or, in several cases, peripheral vascular surgery with normothermia. RESULTS: In all patients, measurements of bilateral phrenic nerve function were within normal limits before surgery. Three weeks after surgery, left phrenic nerve function was absent in five patients in the CPB and hypothermia group (3 in CABG and 2 in valve replacement). No phrenic nerve dysfunction was observed after surgery in the CABG with beating heart (no CPB) or the peripheral vascular groups. Except in the five patients with left phrenic nerve paralysis, mean phrenic nerve conduction latency time (ms) and amplitude (mV) did not differ statistically before and after surgery in either group (p > 0.05). CONCLUSIONS: Our results indicate that CPB with hypothermia and local ice-slush application around the heart play a role in phrenic nerve injury following cardiac surgery. Furthermore, phrenic nerve injury during cardiac surgery occurred in 10.2 % of our patients (CABG with CPB plus valve surgery). (+info)
Bilateral diaphragmatic paralysis and related respiratory complications in a patient with West Nile virus infection.
The case report is presented of a patient with West Nile virus infection and ventilator dependent respiratory failure in whom bilateral diaphragmatic paralysis developed. If the prevalence of West Nile virus infection continues to rise, recognition of diaphragmatic paralysis and related respiratory complications will become increasingly important to the pulmonary/critical care physician. (+info)
Cardiac ECMO for biventricular hearts after paediatric open heart surgery.
OBJECTIVE: To delineate predictors of hospital survival in a large series of children with biventricular physiology supported with extracorporeal membrane oxygenation (ECMO) after open heart surgery. RESULTS: 81 children were placed on ECMO after open heart surgery. 58% (47 of 81) were transferred directly from cardiopulmonary bypass to ECMO. Hospital survival was 49% (40 of 81) but there were seven late deaths among these survivors (18%). Factors that improved the odds of survival were initiation of ECMO in theatre (64% survival (30 of 47)) rather than the cardiac intensive care unit (29% survival (10 of 34)) and initiation of ECMO for reactive pulmonary hypertension. Important adverse factors for hospital survival were serious mechanical ECMO circuit problems, renal support, residual lesions, and duration of ECMO. CONCLUSIONS: Hospital survival of children with biventricular physiology who require cardiac ECMO is similar to that found in series that include univentricular hearts, suggesting that successful cardiac ECMO is critically dependent on the identification of hearts with reversible ventricular dysfunction. In our experience of postoperative cardiac ECMO, the higher survival of patients cannulated in the operating room than in the cardiac intensive care unit is due to early effective support preventing prolonged hypoperfusion and the avoidance of a catastrophic cardiac arrest. (+info)
An unusual cause of bilateral diaphragmatic paralysis.
In a patient who had a sudden onset of bilateral diaphragmatic paralysis after forceful neck manipulation complete, though gradual, recovery in lung function and transdiaphragmatic pressures was seen over three years. This is a previously unrecognised risk of neck osteopathy. (+info)
Upper airway afferents are sufficient to evoke the early components of respiratory-related cortical potentials in humans.
Repeated inspiratory occlusions in humans elicit respiratory-related cortical potentials, the respiratory counterpart of somatosensory-evoked potentials. These potentials comprise early components (stimulus detection) and late components (cognitive processing). They are considered as the summation of several afferent activities from various part of the respiratory system. This study assesses the role of the upper airway as a determinant of the early and late components of the potentials, taking advantage of the presence of a tracheotomy in patients totally or partially deafferented. Eight patients who could breathe either through the mouth or through a tracheotomy orifice (whole upper airway bypassed) were studied (4 quadriplegic patients with phrenic pacing, 4 patients with various sources of inspiratory pump dysfunction). Respiratory-related evoked potentials were recorded in CZ-C3 and CZ-C4. They were consistently present after mouth occlusions, with a first positive P1 and a first negative N1 components of normal latencies (P1: 40.4 +/- 6.1 ms in CZ-C3 and 47.6 +/- 7.6 ms in CZ-C4; N1: 84.4 +/- 27.1 ms in CZ-C3 and 90.2 +/- 17.4 ms in CZ-C4) and amplitudes. Tracheal occlusions did not evoke any cortical activity. Therefore, in patients with inspiratory pump dysfunction, the activation of upper airway afferents is sufficient to produce the early components of the respiratory-related evoked cortical potentials. Per contra, in this setting, pulmonary afferents do not suffice to evoke these components. (+info)