Donald F. Proctor

The stability of peripheral airways

Abstract We cannulated bronchioles in excised cat lobes and measured their opening and closing pressures and pressure volume curves before and after flushing them with either Tween or dog surfactant. Tween decreased the opening pressures and increased the closing pressures, whereas surfactant had little effect on either. The pressure volume curve was changed following Tween so that inflation pressures were less. The deflation pressure volume curve intersected the control curve so that at high volumes the distending pressures were less following Tween but at low lung volumes the opposite was true. Lead dust bronchograms taken at low lung volumes revealed no evidence of catenoid formation. Compression of the surface lining bronchioles was accomplished primarily by changes in length. We conclude that surfactant lines and stabilizes bronchioles, protecting against excessive radius changes with lung volume and air trapping.

Human response to controlled levels of sulfur dioxide.

Nasal mucus flow rate, airway resistance, and subjective response was studied in 15 young men during six-hour exposures to 1, 5, and 25 ppm sulfur dioxide (SO2). A significant decrease in nasal mucus flow rate during 5- and 25-ppm exposures was observed. This decrease was greatest in the anterior nose and in subjects with an initially slow mucus flow rate. Pharyngeal air samples yielded less than 1% of the SO2 inhaled, even after a six-hour exposure to 25 ppm SO2. An increased nasal airflow resistance and a fall in forced expiratory volume in one second and forced expiratory flow during the middle half of expired volume was found at all exposure levels, but there was no change in “closing volume.” Discomfort was proportional to SO2 concentration, but never excessive. Subjects with initially slow nasal mucus flow rates experienced the greatest discomfort. The acute effects of SO2 exposure appear to justify reduction of the present threshold limit value of 5 ppm to 1 ppm, and provide support for a nasobronc...

A Comparison of Nasal and Tracheobronchial Clearance

Tracheobronchial clearance and nasal clearance were compared in 13 pairs of monozygotic twins and 11 nontwins. Tracheobronchial clearance was studied by having the subjects inhale, by mouth, a test aerosol of 6μmol particles tagged with technetium Tc 99m (99mTc) and making external measurements of the radioactivity. Nasal clearance was studied with two methods: (1) a 0.6-mm anion resin particle tagged with 99mTc was externally followed at five different points along the nasal passage and (2) a saccharine particle was placed on the mucociliary mucosa anteriorly in the nose and the time was registered until the subject noted a sweet taste. A weak positive association existed between tracheobronchial clearance and nasal clearance as studied with the saccharine particle method, but no association was found between tracheobronchial clearance and nasal clearance as tested by the tagged resin particle method.

Human Response to 78-Hour Exposure to Dry Air

We studied the effects of dry air on nasal mucus flow rate, nasal resistance, forced vital capacity, skin resistance, and discomfort in eight young healthy men exposed to clean air at 23 C in a climate chamber. After 27 hours at 50% relative humidity (RH) they lived for 78 hours at 9% RH and then returned to the initial level of 50% RH for 20 hours. No significant changes were observed in the nasal mucus flow rate throughout the experiment. Nor did a tenfold increase in nasal respiration during 20-minute periods of exercise in the dry air cause any change in mucus flow rate. No changes were observed in nasal or tracheobronchial resistance except for a 58% increase in calculated cross-sectional nasal area during exercise. The humidity voting for the subjects varied widely and related poorly to the humidity conditions; the average votings always were in the comfort range. No discomfort was reported from the body surfaces, and skin resistance did not change. The study indicates that there is no physiological...

Mucociliary Function during Experimentally Induced Rhinovirus Infection in Man

In conjunction with a controlled study of the effect of vitamin C on susceptibility to experimentally induced rhinovirus infections in man, we have conducted a study of nasal mucociliary function in the subjects volunteering for the study. In the 21 volunteers an average mucociliary flow rate (measured by the Quinlan tagged particle technique) of 7.5 mm/min was found in those with normal nasal morphology and 4.0 mm/min in those with abnormal nasal morphology. The rates decreased during infection in both groups but at different times after induction of infection. Ascorbic acid had no effect on either susceptibility to induced rhinovirus infection or mucociliary transport.

Human Nasal Mucosal

We have measured nasal mucociliary transport rates once in 58 subjects and, in 22 of these, three additional times at intervals of two hours. The study was performed under controlled climatic conditions (with a temperature of 23 C and relative humidity of 68%). The subjects could be classified in three groups: 32 who had a rapid uninterrupted particle movement, 14 who had a stop or slowdown in particle movement after an initial normal flow, and 10 who had either a constantly slow particle movement or stasis during the experiment. The transport rates in the first group ranged from 0.23 to 2.36 cm min-1, with an average of 0.84 cm min-1. In the subjects studied four times at two-hour intervals, some exhibited marked changes in transport rates during the eight-hour day.

PRESSURE‐FLOW EVENTS DURING SINGING

The singer must coordinate the movements of the vocal cords and the vocal tract (which determine pitch, loudness, and quality of the tones) with the movements of the respiratory bellows (which produce the pressure and flow of air needed to drive the larynx). During phonation, both subglottic pressure and the flow rate of air through the larynx must remain constant if one wants to produce a tone of constant pitch and loudness. During singing of a song, on the other hand, these pressures and flow rates are subject to changes related to the requirements of the individual tones. We will briefly discuss breathing patterns during singing of songs, but will concentrate on the pressure and flow events during production of single constant tones, when a “steady state” of pressure and flow rate prevails. The mechanical analy3is of these events will be summarized only; its details have been reported elsewhere, as have the technical details of the methods used (Bouhuys et al., 1966).

Human nasal mucosal function at controlled temperatures.

We exposed 16 healthy human volunteers to air temperatures ranging from 7 to 39 degrees C and measured nasal mucus flow, nasal airflow resistance, forced vital capacity, rectal and body surface temperature, and air temperature within the nasal passage. A moderate fall in nasal mucus flow rate in the anterior and middle parts of the nose was observed with temperature above or below 23 degrees C. The nasal airflow resistance decreased in warm air and tended to increase in cold air. No significant changes in forced vital capacities or rectal temperature were observed. Nasopharyngeal end inspiratory air temperatures at 23 degrees C averaged 32.6 degrees C. At environmental temperatures of 15 and 31 degrees C they average 28.1 and 32.8 degrees C, respectively. Although we found alterations in upper airway function associated with altered inspired air temperature, over the range of 32 degrees C studied these changes were of minor physiological significance.

Nasal Resistance: Description of a Method and Effect of Temperature and Humidity Changes

The study of nasal resistance to air flow is important for the understanding of nasal function. The possibility of a relationship between nasal function and pulmonary mechanics suggests that nasal resistance may prove to be more important than has been so far assumed.1O·13.15 This idea is further supported by a recently described pediatric syndrome of cor pulmonale secondary to hypertrophied adenoids.t!

Flexible fiberoptic bronchoscopy. Its place in the search for lung cancer

The use of sputum cytology has demonstrated that conventional bronchoscopic equipment often fails to permit localization of earlier, more peripheral tumors. The flexible fiberbronchoscope now opens up new bronchial horizons but does not replace rigid instruments. Our experience in 300 fiberoptic studies has suggested certain guidelines for determining in which patients the flexible equipment should be used and in which conventional instruments are preferred. By means of a comprehensive endoscopic study, we successfully localized eight “sputum positive,” radiologically occult bronchogenic carcinomas. The fiberbronchoscope is essential in searching the segments for subtle changes of early cancer. These findings are documented by a color television system. A detailed pathological study demonstrates the importance of preoperative marginal biopsies in excluding carcinoma in situ which may extend some distance from even small tumors. In 94 patients with cancer we located 85 (90%) by direct visualization and/or bronchoscopic specimens. Sixty-eight (72%) involved primarily the segmental or more peripheral areas while main bronchus tumors were large and suggested spread from a more distal site of origin. The fiberbronchoscope has greatly extended our capabilities, allowing a better understanding of early lung cancer and greatly improved localization.