Biomedical subjects
Publications and source records attributed to R C Bone.
Acute respiratory failure can result from a wide variety of etiologies. Hypoxemia is the hallmark of this condition and is responsible for the major clinical signs and symptoms. The use of arterial blood gas analysis is the cornerstone of diagnosis and is also critical in the subsequent evaluation of the effectiveness of therapy. Treatment must be individualized and coordinated in the setting of an intensive care unit.
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Septic pulmonary injury remains a significant cause of morbidity and mortality among hospitalized patients today and is likely to increase in prevalence as advances in medical technology allow the salvage of more critically ill and immunocompromised hosts. Treatment of the host's underlying disease and even of the infection itself has appeared to redeem septic patients only to have them succumb in increasing numbers to the pulmonary injury reaction. Our understanding of the mechanisms and mediators of lung dysfunction in sepsis is in a rapidly expanding phase. Currently we recognize the contributions of several blood elements, lipids, and peptides to pulmonary injury, although the relative importance and points of interaction and interdependence of these mediators remain to be established. It is hoped that a more complete understanding of the process of pulmonary injury in sepsis will suggest effective means of intervention at a stage in which damage may be reversed or minimized.
At rest and during exercise, noninvasive studies of cardiopulmonary physiology in patients with chronic obstructive pulmonary disease (COPD) were carried out to determine the objective benefits of commonly used oral bronchodilator drugs in 15 stable patients without cardiovascular disease or reversible obstruction of airflow. Theophylline, terbutaline, a combination of theophylline and terbutaline, and placebo were given for ten days each in a randomly sequenced double-blind protocol for outpatients. Spirometric values, the ratio of physiologic dead space to tidal volume (VDp/VT), and the alveolar-arterial oxygen pressure difference (P[A-a]O2) were studied at rest on each regimen. During steady-state exercise the changes in VDp/VT and P(A-a)O2, as well as the ventilatory equivalent for oxygen and oxygen pulse, were measured. When compared with placebo, no significant change was noted in the previously mentioned measurements with any regimen, with the exception of a small improvement in the forced expiratory volume in one second, which was significant for all regimens. These findings suggest that commonly used oral bronchodilator drugs in usual doses may have small effects on airflow even in "irreversible" COPD but that the objective effect of these agents on gas exchange during rest and exercise is not significant.
Although Haemophilus influenzae is becoming recognized as a cause of serious pulmonary infections in adults, it has not been previously reported to infect lung cysts. We describe a 25-year-old man who had a lung cyst in which a serious infection developed. Both needle aspiration of the cyst and blood culture confirmed that the infection was caused by H influenzae.
Measurement of deposition of sidestream cigarette smoke in the human respiratory tract is important for assessing the health effects of sidestream cigarette smoke. We measured the deposition fraction of sidestream cigarette smoke in 5 normal adult male volunteers using sidestream smoke at a concentration similar to that encountered indoors with smokers present. The mean deposition was 11%. These data indicate that the deposition fraction of sidestream smoke is similar to other previously studied aerosols in the same size range and is much less than mainstream smoke.
Investigation of the effect of cigarette smoke on the serum trypsin inhibitory capacity (TIC) and antitrypsin content in 89 smokers compared with 37 nonsmokers revealed that cigarette smoking is associated with a significantly lower level of TIC. No alteration in serum antitrypsin content was found because of cigarette smoking. Further analysis of the data indicated a correlation between the magnitude of smoking and the reduction in serum TIC. The reduction of TIC in cigarette smokers is consistent with the recent findings of decreased alpha 1-antitrypsin activity in rat lung and the reduced elastase inhibitory capacity per mg of alpha 1-antitrypsin found in the serum of smokers. The decrease in TIC in the serum of smokers, in addition to the reported decrease in elastolytic activity, may be useful in explaining the pathogenesis of emphysema frequently found in smokers.
The participation of prostaglandins in the physiologic alterations of endotoxin shock has been well established with the aid of prostaglandin synthetase inhibitors. Our study was designed to investigate the potential of ibuprofen, a highly specific cyclooxygenase inhibitor, to reverse the hemodynamic and acid base abnormalities of canine endotoxin shock. Mean blood pressure fell to 49.8 +/- 6.6 mm Hg in dogs given endotoxin by 5 min after injection, and remained below 83 mm Hg for the duration of the 120-min observation period. In animals given endotoxin followed by ibuprofen, a similar initial drop of systemic blood pressure was seen, but it subsequently recovered to 150.2 +/- 4.1 mm Hg by 120 min (P less than 0.001). Cardiac index increased in animals given ibuprofen (2.3 +/- 0.28 liter/m2 per min) compared with animals given endotoxin alone (1.0 +/- 0.09 liter/m2 per min) by termination of the experiment. The arterial pH dropped in endotoxin treated animals to 7.18 +/- 0.03 by 120 min. Ibuprofen prevented the acidosis, the final pH in ibuprofen and endotoxin treated animals measuring 7.36 +/- 0.01. We conclude that ibuprofen protects against the hypotension, acidosis, and depression of cardiac index of canine endotoxin shock.
Energy dispersive x-ray analysis (EDXA) or "microprobe analysis" provides cochlear physiologists with a means of accurately assessing relative ionic concentrations in selected portions of the auditory mechanism. Rapid freezing followed by lyophilization allows the recovery of fluid samples in crystalline form not only from perilymphatic and endolymphatic spaces, but also from much smaller subregions of the cochlea. Because samples are examined in a solid state, there is no risk of diffusion into surrounding or juxtaposed fluids. Samples of cochlear tissues may also be evaluated without the danger of intercellular ionic diffusion. During direct visualization by scanning electron microscopy, determination of the biochemical makeup of the material being examined can be simultaneously, assuring the source of the data collected. Other potential advantages and disadvantages of EDXA are reviewed. Initial findings as they relate to endolymph, perilymph, stria vascularis, and the undersurface of the tectorial membrane are presented.
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A combined regimen of kanamycin sulfate treatment (175 mg/kg/day) and behavioral evaluation of resulting audiometric threshold shifts was used to produce selective outer hair cells (OHC) loss in chinchillas. This protocol resulted in a 3-7 mm region in the cochlear base in which OHCs were completely absent and inner hair cells (IHCs) were largely resent and normal at both light and electron microscopic levels. Partial OHC loss was associated with audiometric threshold shifts in excess of 15 dB, while complete OHC loss was associated with audiometric threshold shifts in excess of 40 dB. After recovery periods of at least three weeks, phase-locking was examined across frequency for auditory nerve (VIIIth nerve) and ventral cochlear nucleus (VCN) neurons. The frequency range for neural phase-locking in normal subjects extended up to approximately 4 kHz for VIIIth nerve fibers and 3 kHz for VCN neurons. Following kanamycin intoxication, however, the frequency range for neural phase-locking in both of these auditory regions varied with characteristic frequency (CF): neurons whose CF corresponded to normal cochlear regions exhibited phase-locking throughout the normal frequency range; neurons whole CF corresponded to cochlear regions with selective OHC loss exhibited a marked reduction in the frequency range over which they could phase-lock.
Treatment of respiratory failure in the patient with chronic obstructive lung disease requires the use of a controlled oxygen, treatment of reversible causes of deterioration, and treatment of the associated bronchospasm. Complications such as pulmonary emboli and gastrointestinal bleeding should be avoided by prophylactic therapy. Mechanical ventilation should be avoided if possible. If the patient requires intubation, weaning and extubation should be an orderly transition to spontaneous ventilation. Nutritional support should be stressed during respiratory failure. Finally, as explained in detail in other chapters, a comprehensive outpatient treatment program should be planned prior to discharge from the hospital. A comprehensive approach to management should improve the quality of life and further improve survival in the patient with chronic obstructive lung diseases.
The contemporary Head and Neck surgeon has a choice of tissue available for defect closure. Depending on the situation, either traditional or newer means of reconstruction may best fit the patients' needs. More recently described procedures include free flaps (anastomosis by microvascular surgery to a nearby vascular supply) and myocutaneous flaps, a new concept in pedicle transfer. Both of these latter techniques improve and partially supplant, but do not entirely replace other older methods of repair.
Ninety-eight patients admitted to our respiratory intensive care unit during a one-year period were compared retrospectively with 99 well-matched patients admitted during a second one-year period. The use of prophylactic low-dose heparin in the second year was associated with a significant decrease in pulmonary emboli documented by ventilation-perfusion scan, pulmonary angiography, and autopsy. No specific bleeding complications could be directly attributed to the use of low-dose heparin. The frequency and severity of gastrointestinal hemorrhage as determined by hemoglobin fall and transfusion requirements were not significantly affected by the prophylactic use of low-dose heparin. Low-dose heparin appears to be effective and safe in respiratory intensive care unit patients in the prevention of pulmonary emboli.
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This work describes results of measurements made to determine the size distribution of commonly used medical aerosols and the effect of high humidity on size distribution of some of those aerosols. If therapeutic aerosol particles change size considerably at high humidity, deposition quantity and site in the respiratory tract could be altered. If there is little change in size at high humidity, deposition could be estimated using theoretical deposition methods devised for deposition of stable particles. The results of this work suggest that the aerosol produced by most metered dose bronchodilator devices does not change size very much at high humidity.
Physical properties of two metered-dose bronchodilator aerosols packaged as solutions and two aerosols packaged as finely ground powders were measured at low and high relative humidity. The aerodynamic size distribution and particle concentration were measured in real time using the single-particle aerodynamic relaxation time analyzer, which can measure the aerodynamic diameter of single suspended particles in the respirable size range. The count median aerodynamic diameter, the mass per dose were calculated. Significant increases were noted in the count median aerodynamic diameter, the total particles per dose, and the total aerodynamic mass median aerodynamic diameter for three aerosols and in the mass median aerodynamic diameter for two aerosols. The number of particles in the measured size range increased 3.6- and 4.1-fold for the droplet aerosols and 1.4-fold for the powder preparations. The aerodynamic mass per dose in the measured size range increased 5.7- and 11.4-fold for the droplet aerosols and 3.1- and 1.6-fold for the powder aerosols. These data indicate that all aerosols tested increased in size at high humidity and that aerosols dispensed as droplets may be more unstable than those dispensed as powders.