Biomedical subjects

M P Highcock

Publications and source records attributed to M P Highcock.

3 recordsLinked to original sources

PubMed2003

Increased ventilation with NiIPPV does not necessarily improve exercise capacity in COPD.

Evidence that noninvasive intermittent positive-pressure ventilation (NiIPPV) improves exercise capacity in chronic obstructive pulmonary disease (COPD) is limited. The effectiveness of different ventilators in this setting has not been studied. Three bilevel pressure support ventilators (Bipap S/T 30, Nippy2 and Vpap II ST), applied via a mouthpiece, were compared during submaximal treadmill exercise in eight subjects with COPD. Subjects walked to exhaustion with each of the ventilators and while breathing through the mouthpiece alone, in random order. In addition, four unencumbered walks were performed. The unencumbered distance (mean +/- SD) walked was 259 +/- 123 m. With the mouth-piece alone this decreased to 211 +/- 96 m and fell further to 145 +/- 76 m with NiIPPV. There was no difference between the brands of ventilator. At the break-point of exercise, significant increases were seen in tidal volume and minute ventilation in the ventilator walks compared with the mouthpiece alone. Noninvasive intermittent positive-pressure ventilation increased ventilation but did not improve exercise capacity in the subjects in this study. No significant differences were seen between the ventilators. The effectiveness of this technique and the optimal method of assistance require further clarification.

Aged↗

PubMed2002

An overnight comparison of two ventilators used in the treatment of chronic respiratory failure.

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.

Adult↗

PubMed2001

Functional differences in bi-level pressure preset ventilators.

The performance of four bilevel positive pressure preset ventilators was compared. The ventilators tested were; BiPAP ST30 (Respironics); Nippy2 (B + D Electrical); Quantum PSV (Healthdyne); and Sullivan VPAP H ST (Resmed). A patient simulator was used to determine the sensitivity of the triggering mechanisms and the responses to a leak within the patient circuit, and to changes in patient effort. Significant differences (p <0.05) between the devices were seen in the trigger delay time and inspiratory trigger pressure. When a leak was introduced into the patient circuit, the fall in tidal volume (VT) was less than ten per cent for each ventilator. The addition of patient effort produced a number of changes in the ventilation delivered. Patient efforts of 0.25 s induced a variable fall in VT. An increase in VT was seen with some ventilators with patient efforts of 1 s but the effect was variable. Trigger failures and subsequent falls in minute volume were seen with the BiPAP and the Nippy2 at the highest respiratory frequency. Differences in the responses of the ventilators are demonstrated that may influence the selection of a ventilator, particularly in the treatment of breathless patients with ventilatory failure.

Humans↗