Adaptive support ventilation prevents ventilator-induced diaphragmatic dysfunction in piglet: an in vivo and in vitro study.
ABSTRACT Contrary to adaptive support ventilation (ASV), prolonged totally controlled mechanical ventilation (CMV) results in the absence of diaphragm activity and causes ventilator-induced diaphragmatic dysfunction. Because maintaining respiratory muscles at rest is likely a major cause of ventilator-induced diaphragmatic dysfunction, ASV may prevent its occurrence in comparison with CMV. The aim of our study was to compare the effects of ASV with those of CMV on both in vivo and in vitro diaphragmatic properties.
Two groups of six anesthetized piglets were ventilated during a 72-h period. Piglets in the CMV group (n = 6) were ventilated without spontaneous ventilation, and piglets in the ASV group (n = 6) were ventilated with spontaneous breaths. Transdiaphragmatic pressure was measured after bilateral, supramaximal transjugular stimulation of the two phrenic nerves. A pressure-frequency curve was drawn after stimulation from 20 to 120 Hz of the phrenic nerves. Diaphragm fiber proportions and mean sectional area were evaluated.
After 72 h of ventilation, transdiaphragmatic pressure decreased by 30% of its baseline value in the CMV group, whereas it did not decrease in the ASV group. Although CMV was associated with an atrophy of the diaphragm (evaluated by mean cross-sectional area of both the slow and fast myosin chains), atrophy was not detected in the ASV group.
Maintaining diaphragmatic contractile activity by using the ASV mode may protect the diaphragm against the deleterious effect of prolonged CMV, as demonstrated both in vitro and in vivo, in healthy piglets.
- Critical care medicine 02/2014; 42(2):492-4. · 6.37 Impact Factor
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ABSTRACT: In anaesthetized patients scheduled for surgery, tracheal intubation is performed with the expectation of subsequent smooth extubation. In critically ill patients, separation from the ventilator is often gradual and the time chosen for extubation may be either delayed or premature. Thus, weaning is challenging, represents a large part of the ventilation period and concerns all mechanically ventilated patients surviving their stay. Weaning may be stratified in three groups according to its difficulty and duration. In simple weaning the main issue is to detect the soonest time to start separation from the ventilator; this is frequently impeded by poor sedation management and excessive ventilator assistance. A two-step diagnostic approach is the most efficacious: screening for ascertained readiness to wean is confirmed by a diagnostic test simulating the post-extubation period, best performed by unassisted breathing (no PEEP). In case of test failure (difficult weaning), a structured and thorough diagnostic work-up regarding potentially reversible pathologies is required with a focus on cardiovascular dysfunction or fluid overload at the time of separation from the ventilator, respiratory or global muscle weakness and underlying infection. Prolonged weaning is exceptionally time- and resource-consuming, needs to properly appraise psychological problems, sleep and nutrition, and is probably best performed in specialized units. Adequately managing simple and difficult weaning requires one to think about ICU policies in terms of sedation, fluid balance and having a systematic screening strategy; it also needs an individualized approach to understand and treat the failing patients. Prolonged weaning requires a holistic approach.European Journal of Intensive Care Medicine 07/2013; · 5.17 Impact Factor
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ABSTRACT: The diagnosis of intensive care unit acquired weakness (ICUAW) in the setting of neurological rehabilitation is steadily increasing. This is due to the fact that the intensive care of patients with sepsis or after cardiac or abdominal surgery is improving. A longer duration of respiratory weaning and comorbidities frequently complicate rehabilitation. Clinically, patients present with a flaccid (tetra) paresis and electrophysiological studies have shown axonal damage. Besides involvement of peripheral nerves, muscle can also be affected (critical illness myopathy) leading to ICUAW with inconstant myopathic damage patterns found by electrophysiological testing. Mixed forms can also be found. A specific therapy for ICUAW is not available. Early mobilization to be initiated on the intensive care unit and commencing neurological rehabilitation improve the outcome of ICUAW. This review highlights the current literature regarding the etiology and diagnosis of ICUAW. Furthermore, studies about rehabilitation and outcome of ICUAW are discussed.Der Nervenarzt 01/2014; · 0.80 Impact Factor