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Biomedical subjects

R M Olson

Publications and source records attributed to R M Olson.

8 recordsLinked to original sources
PubMed1978

Effects of using long breathing hoses upon mask pressure.

Effects of using oxygen breathing hoses from 0.9 to 8.2 m (3 to 27 ft) long and mask fit upon mask pressure during 0.75 to 12-s decompressions from 2,438 m (8,000 ft) to either 6,096, 10,668, or 15,240 m (20,000, 35,000 or 50,000 ft) were determined. Peak mask pressures and duration of high mask pressure were related to mask fit, mask and hose stretch compliance, pressure differential, decompression rate, and other factors, with mask pressure increasing with hose length. Peak mask pressures frequently exceeded 80 mm Hg, a high pressure associated with increased incidence of pulmonary damage. Cargo-type aircraft, however, have sufficiently large volumes so that they will not decompress rapidly enough to have high mask pressure, even with an 8.2-m long hose. Long breathing hoses should not be used in smaller aircraft since small cabin volume will result in rapid decompression rates and high mask pressure. Above a flight altitude of 2,438 m, oxygen should always be breathed if hoses longer than 2.9 m (9 ft) are used. This would help prevent hypoxia, associated with the need to deplete air in the hose before oxygen is breathed, should cabin pressure be lost at a high altitude. The fastest decompression rates compatible with preventing mask pressures from exceding 80 mm Hg during decompressions to different altitudes with different length breathing hoses are given.

Aerospace Medicine↗
PubMed1978

Effects of long-hose breathing.

The need for aircrew members to use long breathing hoses between regulator and mask arises in the design of new transport aircraft and in several cargo operations requiring an open rear door. In this study, induced work of breathing through long hoses, the resulting changes in oxygen consumption, and comfort were studied in relation to altitude, hose length, and exercise level. Conclusions were that, above 18,000 ft (5.5 km), a 30-ft (9.1-m) hose is acceptable for all reasonable work levels; for altitudes between 13,000 and 18,000 ft (4.0 and 5.5 km), the hose length should preferably be 18 ft (5.5m), and at altitudes below 13,000 ft (4.0 km), hose length should be limited to 12 ft (3.6). Moreover, at ground level, the hose length should be limited to 6 ft (1.8 m) for all but sedentary activity. Should the potential for rapid decompression exist, at any altitude, volume considerations limit hose length to 18 ft (5.5 m) since larger hoses possess excessive regulator-to-mask dead space.

Adult↗
PubMed1976

Economical oxygen-delivery system.

The conservation of aircraft oxygen supplies is becoming of considerable interest to the Air Force. Onboard oxygen-generating systems are being developed which could support an aircrew if oxygen produced by these systems were used conservatively. These experiments studied the conservation potential of a rebreather bag placed in a vented container near the regulator in an oxygen-delivery system. The bag's volume was close to that of the subject's physiologic dead space. When the subject exhaled, oxygen in the mouth, trachea, and mask dead space went to the rebreather bag, to be rebreathed with the next breath. The CO2-contaminated oxygen from the alveoli was vented to the cabin. The dead-space oxygen could be separated from contaminated oxygen because dead-space air is exhaled first with each breath. When the rebreather-bag volume matched the subject's physiologic dead space so that no CO2 accumulated, a 30% oxygen savings was realized. When the bag was large enough to realize a 50% savings, CO2 accumulation was only 2%.

Aviation↗
PubMed1976

Intravascular bubbles associated with intravenous injections and altitude.

Ultrasonically detected microbubbles were more abundant in the pulmonary artery of dogs intravenously injected with 10 ml of saline than in the same noninjected controls during 10,000 ft (3,048 m), 20,000 ft (6,096 m), and 40,000 ft (12,192 m) exposures. Continuous intravenous (i.v.) drip infusions also introduced many small bubbles. Since they may serve as "nuclei" for visible intravascular bubble formation, are sometimes associated with decompression sickness, and are additionally considered undesirable, it would appear prudent to minimize i.v. injections immediately before flights. However, a 10-min delay before ascent will reduce their number and a 60-min delay will insure their almost complete absence. Also, slow ascent, a 1-h denitrogenation time, or use of a degassed solution will help reduce their total number.

Aerospace Medicine↗
PubMed1975

Blood flow during 2-Torr exposures at different decompression rates.

Central and peripheral blood flow of denitrogenated dogs, measured in the femoral artery and aorta, declined rapidly and ceased within mean times of 28, 35, 70, or 90 s after 1-, 10-, 30-, or 60-s decompressions from 258 Torr to 2 Torr, respectively. Neither arterial nor venous hypoxemia was seen after 1-s decompressions since the hypoxic blood did not reach the aorta. In contrast, arterial and venous O2 saturation levels dropped as low as 12 or 6% following 10- to 60-s decompressions since circulation continued. A severe and transient decerebratelike rigidity and subsequent temporary flaccid paralysis of the hind legs was seen during recovery from decompressions slower than 1 s, whereas only a mild temporary flaccid paralysis was frequently present after 1-s decompression. The more severe responses following 10- to 60-s decompressions are associated with the greater hypoxemia after slow decompressions, indicating tissue hypoxia is more severe when decompression rate is slow.

Animals↗
PubMedDate not supplied

Human carotid artery diameter and flow by a noninvasive technique.

This paper presents a technique tested in vitro and in dogs and used in humans to measure carotid artery blood flow continuously by placing a transducer on the skin over the artery. The tranducer consists of a pulse echo crystal used to locate the carotid artery and measure its diameter and wall velocity. It also has a pair of Doppler shift crystals used to measure the velocity of the artery wall and blood flow in the vessel. It was found that the pulsatile artery wall distension was between 8 and 13 percent of the diastolic diameter. The peak blood flow varied inversely with pulse rate. Occlusion of one carotid resulted in an increase in diastolic but not systolic flow in the other.

Adult↗