The electronic demand oxygen delivery device used in this study was the Oxymatic (Chad Therapeutics Inc, Chatsworth, CA). We modified the Oxymatic to add a settable delay of 164, 100, 70, 25 or 1 ms between the beginning of inspiratory flow and initiation of the oxygen pulse. In addition, a pre-inspiratory trigger setting was added to deliver the oxygen pulse at the end of exhalation. Oxygen pulse volume was adjustable and calibrated for each test condition using a pulse spirometer (a device we built to measure the volume of the Oxymatic pulse under simulated patient conditions). Standard nasal cannulas with special fittings at the Oxymatic were used in order to avert pressure separation. The SCOOP transtracheal oxygen catheter (Transtracheal Systems, Denver) was used with an oxygen hose that was modified to connect to the Oxymatic.
Oxygen saturation was measured by pulse oximetry (Ohmeda Medical Inc, Boulder, CO). Respiratory rate and tidal volume were measured using a Respitrace (Ambulatory Monitoring, Inc, Ardsley, NY). The Sa02, tidal volume and breath rate were displayed on the same strip chart recorder.
Two Part Study
This study was conducted in two parts at separate locations and on separate groups of subjects. The nasal oxygen investigation was performed at Casa Colina Hospital for Rehabilitative Medicine, Pomona, CA. The transtracheal investigation was performed at the Institute for Transtracheal Oxygen Therapy, Denver.
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Pulsed Nasal Oxygen Study
Subjects. Seven patients from the Casa Colina Inpatient Pulmonary Rehabilitation Program with either COPD or interstitial pulmonary fibrosis, who were hypoxemic at rest, were asked to volunteer for the study. They were nasal breathers; their respiratory status was stable; they had no primary cardiac problems; they were nonsmokers at the time of the study. Spirometry was performed according to the recommendations of the American Thoracic Society.
Protocol. Patients were comfortably seated with the oximeter probe in position. The Sa02 was first measured while each patient was breathing room air and then while receiving 35-ml pulses of oxygen on the “every breath” Oxymatic setting (setting 4) with the delay settings tested in the following order: 164, 100, 70, 25 and 1 ms. Also, Sa02 was measured while patients received oxygen pulses via the pre-inspiratory trigger. The saturations were incremented and stabilized at each setting before taking a reading and proceeding to the next setting. Under each test condition, the Sa02 signal was allowed to remain stable for at least 5 min prior to recording the saturation data. Analysis of variance was used to compare the Sa02 results.
Pulsed and Continuous Transtracheal Oxygen Study
Subjects. Seventeen patients on SCOOP TTO therapy with mature tracheocutaneous fistulas volunteered for the study. The patients were hypoxemic while breathing room air and had COPD, interstitial pulmonary fibrosis or kyphoscoliosis. They were non- smokers at the time of the study; their respiratory status was stable and they had no primary cardiac problems. Spirometry and room air arterial blood gas analysis were performed. kamagra soft tablets
Protocol. Patients were seated comfortably with a finger oximeter probe in place and Sa02 was measured while they were breathing room air. The TTO flow rate was then adjusted in an attempt to achieve a Sa02 of 92 to 94 percent and the continuous TTO flow rate was recorded. Each patient then received pulsed TTO on the “every breath” Oxymatic setting with a delay of 164 ms and the pulse volume was adjusted in an attempt to achieve a Sa02 of 92 to 94 percent. Subsequently, while maintaining the identical pulse volume, Sa02 was measured with delivery of pulsed TTO with delays of 100, 70, 25 and 1 ms, respectively. Finally, Sa02 was recorded while the oxygen pulse was delivered via the pre- inspiratory trigger. Under each test condition, the Sa02 signal was allowed to stabilize prior to recording the saturation. Analysis of variance was used to compare the Sa02 results. The amount of oxygen used per minute with pulsed transtracheal delivery was calculated for each subject from the actual pulsed volume measurement and the respiratory rate displayed on the recording via the Respitrace. The amount of oxygen used with pulsed delivery was then compared with the liter per minute use with continuous flow TTO therapy.