Biomedical subjects

Frank J Cerny

Publications and source records attributed to Frank J Cerny.

4 recordsLinked to original sources

PubMed2004

Arm work interferes with normal ventilation.

Arm work, by limiting movement of the chest wall and use of the respiratory muscles, may alter breathing pattern and gas exchange sufficiently to interfere with the ability to perform certain tasks. To determine the effects of arm work on breathing pattern during a well-controlled work task, depth of breathing, breathing frequency and end-expiratory lung volume (EELV) were measured at rest and during cycling exercise using an arm and a leg ergometer. Six subjects performed arm work at light, moderate and heavy intensities (30%, 60% and 90% of maximum arm work capacity respectively) and leg work at three intensities where ventilation was matched for that achieved during the arm work. This matching was necessary since the level of ventilation affects the breathing pattern. Subjects breathed on a mouthpiece and tubing that led to automated equipment for the measurement of respiratory variables. Ventilation during arm work was accomplished with a lower depth of breathing, a higher breathing frequency and a decreased EELV compared to leg work. Arm work places increased demands on the ventilatory system, including the muscles of respiration that are also recruited for task performance. The competition for using these muscles for breathing as opposed to a particular work task may result in a compromise in breathing capacity that ultimately may limit the ability to perform tasks requiring sustained heavy use of the arms. These increased demands on the upper body muscles must be considered when evaluating the ability of individuals to perform tasks that involve heavy arm work.

Adult↗

PubMed2004

Ventilatory response to exercise in simulated obesity by chest loading.

INTRODUCTION & PURPOSE: Obesity-related increases of weight on the chest wall are known to decrease lung volume and chest wall compliance, but the effect of this mass loading, independent of other obesity-related complications on the ventilatory response to exercise is unknown. The purpose of this study was to investigate the effect of chest mass loading on the ventilatory response to exercise. METHODS: External chest loading (CL) was used to simulate the effect of moderate obesity (BMI = 32 kg x m). Eight healthy nonobese subjects performed two incremental exercise tests on a cycle ergometer with work rate increasing 25 W every 3 min once without (control; CON) and once with CL. Expiratory reserve volume (ERV), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were measured before each test. During exercise, inspiratory capacity (IC), to estimate changes in end-expiratory lung volume, and inspiratory (TI) and expiratory (TE) duration, tidal volume (Vt), breathing frequency (Fb), minute ventilation (VE), mean inspiratory (Vt/TI) and expiratory (Vt/TE) flow rates, and oxygen consumption (VO2) were measured. RESULTS: Baseline ERV, FVC and FEV1 were lower with CL (P < 0.05). Compared with CON, the peak work rate achieved during exercise with CL was lower and VO2, VE, Fb, Vt/TI, and Vt/TE were higher, and Vt was lower at work rates > or = 100 W (P < 0.05). IC increased progressively in CON during exercise but remained unchanged with CL. CONCLUSION: Obesity-related chest loading decreases lung volumes and increases the mechanical ventilatory constraints during exercise and is likely a critical factor in reducing exercise capacity in obesity.

Adult↗

PubMed2004

Physiologic evidence for the efficacy of positive expiratory pressure as an airway clearance technique in patients with cystic fibrosis.

BACKGROUND AND PURPOSE: Individuals with cystic fibrosis (CF) have large amounts of infected mucus in their lungs, which causes irreversible lung tissue damage. Although patient-administered positive expiratory pressure (PEP) breathing has been promoted as an effective therapeutic modality for removing mucus and improving ventilation distribution in these patients, the effects of PEP on ventilation distribution and gas mixing have not been documented. Therefore, this preliminary investigation described responses in distribution of ventilation and gas mixing to PEP breathing for patients with moderate to severe CF lung disease. SUBJECTS AND METHODS: The effects of PEP breathing on ventilation distribution, gas mixing, lung volumes, expiratory airflow, percentage of arterial blood oxyhemoglobin saturation (SpO(2)), and sputum volume were studied in 5 patients with CF (mean age=18 years, SD=4, range=13-22) after no-PEP, low-PEP (10-20 cm H(2)O), and high-PEP (>20 cm H(2)O) breathing conditions. Single-breath inert gas studies and lung function tests were performed before, immediately after, and 45 minutes after intervention. Single-breath tests assess ventilation distribution homogeneity and gas mixing by observing the extent to which an inspired test gas mixes with gas already residing in the lung. RESULTS: Improvements in gas mixing were observed in all PEP conditions. By 45 minutes after intervention, the no-PEP group improved by 5%, the low-PEP group improved by 15%, and the high-PEP group improved by 23%. Slow vital capacity increased by 1% for no PEP, by 9% for low PEP, and by 13% for high PEP 45 minutes after intervention. Residual volume decreased by 13% after no PEP, by 20% after low PEP, and by 30% after high PEP. Immediate improvements in forced expiratory flow during the middle half of the forced vital capacity maneuver (FEF(25%-75%)) were sustained following high PEP but not following low PEP. DISCUSSION AND CONCLUSION: This study demonstrated the physiologic basis for the efficacy of PEP therapy. The results confirm that low PEP and high PEP improve gas mixing in individuals with CF, and these improvements were associated with increased lung function, sputum expectoration, and SpO(2). The authors propose that improvements in gas mixing may lead to increases in oxygenation and thus functional exercise capacity.

Adolescent↗

PubMedDate not supplied

Neandertal cold adaptation: physiological and energetic factors.

European Neandertals employed a complex set of physiological cold defenses, homologous to those seen in contemporary humans and nonhuman primates. While Neandertal morphological patterns, such as foreshortened extremities and low relative surface-area, may have explained some of the variance in cold resistance, it is suggested the adaptive package was strongly dependent on a rich array of physiological defenses. A summary of the environmental cold conditions in which the Neandertals lived is presented, and a comparative ethnographic model from Tierra del Fuego is used. Muscle and subcutaneous fat are excellent "passive" insulators. Neandertals were quite muscular, but it is unlikely that they could maintain enough superficial body fat to offer much cold protection. A major, high-energy metabolic adaptation facilitated by modest amounts of highly thermogenic brown adipose tissue (BAT) is proposed. In addition, Neandertals would have been protected by general mammalian cold defenses based on systemic vasoconstriction and intensified by acclimatization, aerobic fitness, and localized cold--induced vasodilation. However, these defenses are energetically expensive. Based on contemporary data from circumpolar peoples, it is estimated that Neandertals required 3,360 to 4,480 kcal per day to support strenuous winter foraging and cold resistance costs. Several specific genetic cold adaptations are also proposed--heat shock protein (actually, stress shock protein), an ACP*1 locus somatic growth factor, and a specialized calcium metabolism not as yet understood.

Acclimatization↗