Adaptive Support Ventilation is a novel ventilation mode, a closed-loop control mode that may switch automatically from a PCV-like behaviour to an SIMV-like or PSV-like behaviour, according to the patient status. The operating principles are based on pressure-controlled SIMV with pressure levels and SIMV rate automatically adjusted according to measured lung mechanics at each breath. ASV provided a safe and effective ventilation in patients with normal lungs, restrective or obstructive diseases. In cardiac surgery tracheal extrubation was faster in ASV patients then in controls. In the early weaning phase of acute ventilatory insufficiency the need of resetting ventilator parameters was decreased, suggesting potential benefit for patient care. (+info)
Frequent transmission of enterococcal strains between mechanically ventilated patients treated at an intensive care unit.
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The objectives of this investigation were to study the respiratory tract colonization and transmission of enterococci between 20 patients treated with mechanical ventilation at an intensive care unit (ICU), to compare genotyping with phenotyping, and to determine the antibiotic susceptibilities of the isolated enterococci. Samples were collected from the oropharynx, stomach, subglottic space, and trachea within 24 h of intubation, every third day until day 18, and thereafter every fifth day until day 33. Enterococcal isolates (n = 170) were analyzed by pulsed-field gel electrophoresis and with the PhenePlate (PhP) system. The antimicrobial susceptibilities to five agents were determined. Seventeen of the 20 subjects were colonized with enterococci in the respiratory tract; 12 were colonized in the lower respiratory tract. Genotype analyses suggested that 13 patients were involved in a transmission event, including all patients intubated more than 12 days. In conclusion, colonization of resistant enterococci in the respiratory tract of intubated patients treated at an ICU was common. Transmission of enterococci between patients occurred frequently. Prolonged intubation period seems to be a risk factor for enterococcal cross-transmission. (+info)
Update on modalities of mechanical ventilators.
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Recent advances in ventilator technology have often not been confirmed by randomised trials and instead serious shortcomings have been highlighted. Ventilation modes should only be introduced into routine clinical practice when proved efficacious in appropriately designed studies and no adverse outcomes identified by long term follow up. (+info)
Comment on Re B (Adult: Refusal of Medical Treatment) [2002] 2 All England Reports 449.
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The judgment handed down in the case of Ms B confirms the right of the competent patient to refuse medical treatment even if the result is death. The case does, however, raise some interesting legal points. The facility for conscientious objection by doctors has not previously been explicitly recognised in case law. More importantly perhaps is that the detailed inquiry by the court into Ms B's reasons for refusing treatment, apparently as a precondition for finding her competent, seems to contradict earlier case law where it has been asserted that competent patients can refuse treatment for no reason at all. (+info)
The pulmonary physician in critical care. 10: difficult weaning.
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The study of patients being weaned from mechanical ventilation has offered new insights into the physiology of respiratory failure. Assessment of the balance between respiratory muscle strength, work and central drive is essential if difficulty in weaning occurs, and optimisation of these elements may improve the success of weaning. Psychological support of patients and the creation of units specialising in weaning have also resulted in a higher success rate. (+info)
Different modes of assisted ventilation in patients with acute respiratory failure.
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The aim of the present study was to verify that the patient/ventilator interaction is similar, regardless of the mode of assisted mechanical ventilation (i.e. pressure- or volume-limited) used, if tidal volume (VT) and peak inspiratory flow (PIF) are matched. Therefore, the authors compared the effects of three different modes of assisted ventilation on the work of breathing (WOB) and gas exchange in patients with acute respiratory failure. For Protocol 1, in seven patients, the authors compared pressure support, assist pressure control and assist control (with square and decelerating wave inspiratory flow pattern) set to deliver the same VT and PIF. For Protocol 2, in another 10 patients, the authors compared pressure support and assist control with high (0.8 L x s(-1)) and low (0.6 L x s(-1)) PIFs set to deliver the same VT. In Protocol 1, there was no difference in WOB and gas exchange between the three modes of assisted ventilation tested. In Protocol 2, the decrease of PIFs during assist control significantly increased WOB. In conclusion, different modes of assisted ventilation similarly reduce work of breathing and provide adequate gas exchange at fixed tidal volume and peak inspiratory flow only. During assist control, tidal volume and peak inspiratory flow (set by the physician) are the main determinants of the patient/ventilator interaction. (+info)
An overnight comparison of two ventilators used in the treatment of chronic respiratory failure.
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Differences between bilevel ventilators used for noninvasive intermittent positive pressure ventilation (NIPPV) have been demonstrated during bench testing. However, there are no clinical studies comparing these machines. The authors have previously shown that the Quantum pressure support ventilator and Sullivan variable positive airway pressure II ST differ in performance during bench testing. To examine the clinical significance of this, these two machines were compared in the overnight treatment of subjects with chronic respiratory failure. Ten clinically-stable subjects with thoracic scoliosis were recruited. The subjects were already established on NIPPV, but none were using either of the ventilators to be tested. After familiarisation, the patients used the two ventilators in random order on consecutive nights. Peripheral oxygen saturation and transcutaneous carbon dioxide tension (Pt,CO2) were measured continuously, and sleep was recorded using polysomnography. There were no significant differences in arterial oxygen saturation, Pt,CO2 or sleep duration and quality between the two nights. Despite previously illustrated variation in laboratory performance, no differences were seen between the two ventilators when comparing overnight gas exchange and sleep in vivo. Further study is required to evaluate the significance of the differences found during bench testing in the clinical setting. (+info)
Equipment needs for noninvasive mechanical ventilation.
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Noninvasive mechanical ventilation (NIV) has a long tradition for the treatment of chronic respiratory failure and more recently has also been applied in acute respiratory failure. Based on this experience both critical care ventilators and portable ventilators are used to perform NIV. The individual choice of ventilator type should depend on the patient's condition and also on the expertise of attending staff, therapeutic requirements and the location of care. The majority of studies have used pressure-targeted ventilation in the assist mode. Positive qualities of pressure support ventilation (PSV) are leak compensation, good patient/ventilator synchrony and the option of integrated positive end-expiratory pressure to counteract the effect of dynamic hyperinflation. In this article, some crucial issues concerning PSV (i.e. triggering into inspiration, pressurisation, cycling into expiration and carbon dioxide rebreathing) and some corrective measures are discussed. The parameters which should be monitored during noninvasive ventilation are presented. The interface between patient and ventilator is a crucial issue of noninvasive ventilation. Advantages and disadvantages of face and nasal masks are discussed. Finally, causes and possible remedies of significant air leaks and some technical accessories for noninvasive ventilation are dealt with. (+info)