Biomedical subjects

J Benditt

Publications and source records attributed to J Benditt.

14 recordsLinked to original sources

PubMed1997

Air leaking through the mouth during nocturnal nasal ventilation: effect on sleep quality.

Air leaking through the mouth has been reported in kyphoscoliotic patients receiving nasal ventilation via volume-limited ventilators. This study accessed the frequency of occurrence and effect on sleep quality of air leaking through the mouth during nocturnal nasal ventilation in patients with chest wall and neuromuscular disease using pressure-limited ventilation. Overnight and daytime polysomnography was performed in six stable experienced users of nocturnal nasal noninvasive positive-pressure ventilation (NPPV) who had chronic respiratory failure due to neuromuscular disease or chest wall deformity. All patients used the BiPAP S/T-D ventilatory support system (Respironics, Inc., Murrysville, PA). Measures included sleep scoring, leak quantitation, diaphragm and submental electromyograms (EMGs), and tidal and leak volumes. All patients had air leaking through the mouth for the majority of sleep. Sleep quality was diminished because of poor sleep efficiency and reduced percentages of slow-wave and rapid eye movement (REM) sleep. Air leaking through the mouth was associated with frequent arousals during stages 1 and 2 and REM sleep that contributed to sleep fragmentation, but arousals were infrequent during slow-wave sleep. Despite prevalent leaking, oxygenation was well maintained in all but one patient. Patients used a-combination of passive and active mechanisms to control air leaking. Although nasal ventilation improves nocturnal hypoventilation and symptoms in patients with restrictive thoracic disorders, air leaking through the mouth is very common during use. The leaking is associated with frequent arousals during lighter stages of sleep that interfere with progression to deeper stages, compromising sleep quality. Portable pressure-limited ventilators compensate for leaks, maintaining ventilation and oxygenation, but further studies are needed to determine which interfaces and ventilator techniques best control air leaking and optimize sleep quality.

Adult↗

PubMed1993

Transtracheal delivery of gas decreases the oxygen cost of breathing.

Transtracheally administered gases decrease inspired minute ventilation in both dogs and humans. To test if this is associated with a decrease in the oxygen cost of breathing and to evaluate subsequent changes in the breathing pattern, we studied five patients with chronic respiratory diseases while they spontaneously breathed air and different flows of tracheally administered gases. In a blinded crossover design, the gas consisted of either oxygen or air at 2, 4, and 6 L/min. Oxygen cost of breathing was estimated by the calculation of pleural pressure-time index (PPTI). The pattern of breathing was evaluated utilizing the tension time index for the diaphragm (TTdi). There were significant decreases in PPTI when the patients received 2, 4, and 6 L/min of transtracheal oxygen or air. TTdi also decreased as gas flow increased. This drop was significant at 6 L/min flow for both gases. We conclude that transtracheally administered gas reduces the oxygen cost of breathing. It also changes the respiratory pattern of the diaphragm to a less demanding pattern. This may offer an alternative form of treatment to rest overworked respiratory muscles.

Aged↗

PubMed1993

Estimation of ventilatory reserve by stair climbing. A study in patients with chronic airflow obstruction.

Clinicians and surgeons have used the subjective response to the climb of "one or two flights of stairs" to assess the "reserve" of patients with chronic airflow obstruction (CAO). Very little objective data exist regarding the metabolic and ventilatory cost for any level of stair climbing in these patients. Therefore, this study was designed to evaluate the use of symptom-limited stair climbing as a simple method to estimate the peak oxygen uptake (VO2) and minute ventilation (VE) in patients with CAO. We studied 31 men with varying degrees of CAO, who climbed stairs until they stopped at their symptom-limited maximum. During this climb, timed expired gas was intermittently collected and analyzed, and oxygen saturation and heart and respiratory rates were recorded. The patients achieved 81 +/- 14 percent of their predicted maximal heart rate and 90 +/- 27 percent of their predicted maximal VE. The number of steps or flights climbed correlated linearly with peak VO2 (r = 0.72, p < 0.01) and with VE (r = 0.7, p < 0.01). Stair climbing peak VE, VO2, heart and respiratory rate correlated well with those achieved during standard leg cycle ergometry. The mean +/- SD number of flights climbed was 4.2 +/- 1.7 with most patients (87%) reaching at least 3 flights (54 steps). The group of eight patients with very severe CAO (FEV1 < 0.9 L) climbed 3.4 +/- 0.9 flights (61 +/- 16 steps). We conclude that a symptom-limited maximal stair climb helps estimate peak VO2 and VE in patients with CAO. The frequently advocated test to climb one to two flights to evaluate cardiopulmonary reserve is not adequate for most patients with CAO. Symptom-limited maximal stair climbing is a simple, inexpensive and readily available test that may be used to evaluate the cardiopulmonary reserve of stable patients with CAO.

Adult↗

PubMed1989