Mechanics of the respiratory system in the newborn tammar wallaby

2002 ◽  
Vol 205 (4) ◽  
pp. 533-538 ◽  
Author(s):  
P. M. MacFarlane ◽  
P. B. Frappell ◽  
J. P. Mortola
Keyword(s):  
Respiratory System ◽  
Spontaneous Breathing ◽  
Minute Ventilation ◽  
Pulmonary Ventilation ◽  
Age Groups ◽  
Mechanical Efficiency ◽  
Tammar Wallaby ◽  
Ventilatory Equivalent ◽  
Rate Of Oxygen Consumption ◽  
Respiratory System Resistance

SUMMARY We investigated whether the mechanical properties of the respiratory system represent a major constraint to spontaneous breathing in the newborn tammar wallaby Macropus eugenii, which is born after a very short gestation (approximately 28 days, birth mass approximately 380 mg). The rate of oxygen consumption (V̇O2) through the skin was approximately 33 % of the total V̇O2 at day 1 and approximately 14 % at day 6. The mass-specific resting minute ventilation (V̇e) and the ventilatory equivalent (V̇e/V̇O2) were approximately the same at the two ages, with a breathing pattern significantly deeper and slower at day 1. The mass-specific compliance of the respiratory system (Crs) did not differ significantly between the two age groups and was close to the values predicted from measurements in eutherian newborns. Mass-specific respiratory system resistance (Rrs) at day 1 was higher than at day 6, and also higher than in eutherian newborns. Chest distortion, quantified as the degree of abdominal motion during spontaneous breathing compared with that required to inflate the lungs passively, at day 1 was very large, whereas it was modest at day 6. We conclude that, in the tammar wallaby at birth, the high resistance of the respiratory system and the distortion of the chest wall greatly reduce the mechanical efficiency of breathing. At this age, gas exchange through the skin is therefore an important complement to pulmonary ventilation.

Ontogeny of dry gas hyperpnea-induced bronchoconstriction in guinea pigs

1994 ◽  
Vol 76 (3) ◽  
pp. 1150-1155 ◽  
Author(s):  
T. M. Murphy ◽  
D. W. Ray ◽  
L. E. Alger ◽  
I. J. Phillips ◽  
J. C. Roach ◽  
...  
Keyword(s):  
Respiratory System ◽  
Guinea Pigs ◽  
Minute Ventilation ◽  
Similar Degree ◽  
Fractional Increase ◽  
Respiratory System Resistance ◽  
Key Features

Adolescent guinea pigs (AGPs) demonstrate dry gas hyperpnea-induced bronchoconstriction (HIB) that shares key features with HIB in humans with asthma. The airways of immature animals exhibit enhanced reactivity to diverse types of stimulation. We tested whether dry gas HIB is also increased in newborn guinea pigs (NGPs). We quantified HIB as the fractional increase of respiratory system resistance (Rrs) over baseline (BL) in five 4- to 7-day-old NGPs after 10 min of hyperpnea, as well as changes in Rrs elicited by intravenous methacholine or capsaicin, and compared these responses with those of AGPs. During hyperpnea, analogous stimuli were delivered by mechanically imposing hyperpnea at 3.0, 4.5, and 6.0 times quiet eucapnic minute ventilation (VE). In AGPs, hyperpnea caused significant bronchoconstriction that increased with VE; peak fractional increase of Rrs was 7.6 +/- 2.0 times BL. In contrast, hyperpnea caused insignificant bronchoconstriction in NGPs (1.4 +/- 0.2 times BL after the largest VE; P < 0.05 vs. AGP). Responses elicited by methacholine (10(-10)-10(-7) mol/kg) or capsaicin (0.01–10.0 microgram/kg) were similar in NGPs and AGPs. In AGPs, hyperpnea suppressed HIB until posthyperpnea. To determine whether the reduced HIB of NGPs was caused by enhanced suppression, NGPs and AGPs were administered acetylcholine (10(-10)-10(-7) mol/kg i.v.) during BL eucapnic ventilation and during eucapnic hyperpnea with warm humidified gas. Responses to acetylcholine were suppressed in AGPs and NGPs to a similar degree. We conclude that HIB is markedly diminished shortly after birth in guinea pigs and that it increases substantially during maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ovalbumin-induced lung disease in the pony: role of vagal mechanisms

1982 ◽  
Vol 53 (3) ◽  
pp. 719-725 ◽  
Author(s):  
F. J. Derksen ◽  
N. E. Robinson ◽  
R. F. Slocombe
Keyword(s):  
Respiratory System ◽  
Minute Ventilation ◽  
Left Lung ◽  
Arterial Oxygen Tension ◽  
Lung Compliance ◽  
Arterial Oxygen ◽  
Pulmonary Mechanics ◽  
Vagal Blockade ◽  
Before And After ◽  
Respiratory System Resistance

In awake sensitized ponies, we studied the effect of aerosol ovalbumin challenge on ventilation, pulmonary mechanics, lung volume, and gas exchange before and after vagal blockade. We also challenged the left lung and measured respiratory rate (f) and right and left respiratory system resistance (RrsR, RrsL) before and after both left and bilateral vagal section. Bilateral ovalbumin aerosol challenge increased f, minute ventilation (VE), total respiratory system resistance (Rrs), and minimal volume, decreased dynamic compliance, total lung capacity, and arterial oxygen tension, and was without effect on tidal volume (VT), functional residual capacity, quasi-static lung compliance, and arterial carbon dioxide tension. Vagal blockade reversed the increase in f, VE, and Rrs and increased VT. Challenge of the left lung increased f and RrsL but did not alter RrsR. Bilateral vagal section reversed the tachypnea but unilateral section did not. Histopathologic lesions included acute fibrinopurulent obstructive bronchiolitis, bronchitis, edema, and alveolar distension. We conclude that local mechanisms are of critical importance in the pathogenesis of ovalbumin-induced airway obstruction in ponies, that increased sensitivity of airway smooth muscle to normal vagal tone may also play a role, and that tachypnea following challenge is caused by activity of pulmonary receptors with vagal afferent fibers.

Metabolic and cardiopulmonary responses to wheelchair and bicycle ergometry

1979 ◽  
Vol 46 (6) ◽  
pp. 1066-1070 ◽  
Author(s):  
R. M. Glaser ◽  
M. N. Sawka ◽  
L. L. Laubach ◽  
A. G. Suryaprasad
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Power Output ◽  
Respiratory Exchange Ratio ◽  
Pulmonary Ventilation ◽  
Mechanical Efficiency ◽  
Bicycle Ergometer ◽  
Upper Body ◽  
Bicycle Ergometry ◽  
Ventilatory Equivalent

To evaluate wheelchair activity in reference to a more familiar mode of locomotion, metabolic and cardiopulmonary responses to wheelchair ergometer (WERG) and bicycle ergometer (BERG) exercise were compared. Eighteen able-bodies subjects were tested on a combination wheelchair-bicycle ergometer. Oxygen uptake (VO2), respiratory exchange ratio (R), pulmonary ventilation (VE), ventilatory equivalent (VE/VO2), percent net mechanical efficiency (ME), and heart rate (HR) were determined at power output (PO) levels of 30, 90, and 150 kpm/min on each ergometer. For WERG and BERG exercise, VO2, VE, and HR increased linearly with PO. Generally, VO2, R, VE, VE/VO2, and HR responses were higher (P less than 0.05) during WERG than BERG exercise at each PO. Blood lactate was determined after 150 kpm/min, and found to be higher (P less than 0.05) during WERG than BERG exercise. ME increased with PO and was lower (P less than 0.05) for WERG than BERG exercise at each PO level. The greater metabolic and cardiopulmonary responses observed during WERG exercise may be due to inefficient biomechanics and the relatively small upper body musculature used for propulsion.

scholarly journals Letter to the Editor: Microbiota in the Respiratory System—A Possible Explanation to Age and Sex Variability in Susceptibility to SARS-CoV-2

2021 ◽  
Vol 14 ◽  
pp. 117863612098860
Author(s):  
Vishal Shah
Keyword(s):  
Respiratory System ◽  
Elderly Population ◽  
Age Groups ◽  
The Elderly ◽  
Elderly Adult ◽  
Human Respiratory Tract ◽  
System A ◽  
Number Of Patients ◽  
Children And Young Adults ◽  
Age And Sex

The Human respiratory tract is colonized by a variety of microbes and the microbiota change as we age. In this perspective, literature support is presented for the hypothesis that the respiratory system microbiota could explain the differential age and sex breakdown amongst COVID-19 patients. The number of patients in the older and elderly adult group is higher than the other age groups. The perspective presents the possibility that certain genera of bacteria present in the respiratory system microbiota in children and young adults could be directly or through eliciting an immune response from the host, prevent full-fledged infection of SARS-CoV-2. The possibility also exists that the microbiota in older adults and the elderly population have bacteria that make it easier for the virus to cause infection. I call upon the scientific community to investigate the link between human microbiota and SARS-CoV-2 susceptibility to further understand the viral pathogenesis.

scholarly journals Evaluation of Regional Pulmonary Ventilation in Spontaneously Breathing Patients with Idiopathic Pulmonary Fibrosis (IPF) Employing Electrical Impedance Tomography (EIT): A Pilot Study from the European IPF Registry (eurIPFreg)

2021 ◽  
Vol 10 (2) ◽  
pp. 192
Author(s):  
Ekaterina Krauss ◽  
Daniel van der Beck ◽  
Isabel Schmalz ◽  
Jochen Wilhelm ◽  
Silke Tello ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Electrical Impedance Tomography ◽  
Spontaneous Breathing ◽  
Electrical Impedance ◽  
Statistical Significance ◽  
Pulmonary Ventilation ◽  
Healthy Controls ◽  
Impedance Tomography ◽  
Spontaneously Breathing

Objectives: In idiopathic pulmonary fibrosis (IPF), alterations in the pulmonary surfactant system result in an increased alveolar surface tension and favor repetitive alveolar collapse. This study aimed to assess the usefulness of electrical impedance tomography (EIT) in characterization of regional ventilation in IPF. Materials and methods: We investigated 17 patients with IPF and 15 healthy controls from the University of Giessen and Marburg Lung Center (UGMLC), Germany, for differences in the following EIT parameters: distribution of ventilation (TID), global inhomogeneity index (GI), regional impedance differences through the delta of end-expiratory lung impedance (dEELI), differences in surface of ventilated area (SURF), as well as center of ventilation (CG) and intratidal gas distribution (ITV). These parameters were assessed under spontaneous breathing and following a predefined escalation protocol of the positive end-expiratory pressure (PEEP), applied through a face mask by an intensive care respirator (EVITA, Draeger, Germany). Results: Individual slopes of dEELI over the PEEP increment protocol were found to be highly significantly increased in both groups (p < 0.001) but were not found to be significantly different between groups. Similarly, dTID slopes were increasing in response to PEEP, but this did not reach statistical significance within or between groups. Individual breathing patterns were very heterogeneous. There were no relevant differences of SURF, GI or CGVD over the PEEP escalation range. A correlation of dEELI to FVC, BMI, age, or weight did not forward significant results. Conclusions: In this study, we did see a significant increase in dEELI and a non-significant increase in dTID in IPF patients as well as in healthy controls in response to an increase of PEEP under spontaneous breathing. We propose the combined measurements of EIT and lung function to assess regional lung ventilation in spontaneously breathing subjects.

Intermittent hypoxia increases ventilation and SaO2 during hypoxic exercise and hypoxic chemosensitivity

2001 ◽  
Vol 90 (4) ◽  
pp. 1431-1440 ◽  
Author(s):  
Keisho Katayama ◽  
Yasutake Sato ◽  
Yoshifumi Morotome ◽  
Norihiro Shima ◽  
Koji Ishida ◽  
...  
Keyword(s):  
Intermittent Hypoxia ◽  
Minute Ventilation ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Submaximal Exercise ◽  
Arterial Oxygen ◽  
Hypoxic Exposure ◽  
Hypoxic Ventilatory Response ◽  
Ventilatory Equivalent ◽  
Hypoxic Exercise

The purpose of this study was 1) to test the hypothesis that ventilation and arterial oxygen saturation (SaO2 ) during acute hypoxia may increase during intermittent hypoxia and remain elevated for a week without hypoxic exposure and 2) to clarify whether the changes in ventilation and SaO2 during hypoxic exercise are correlated with the change in hypoxic chemosensitivity. Six subjects were exposed to a simulated altitude of 4,500 m altitude for 7 days (1 h/day). Oxygen uptake (V˙o 2), expired minute ventilation (V˙e), and SaO2 were measured during maximal and submaximal exercise at 432 Torr before (Pre), after intermittent hypoxia (Post), and again after a week at sea level (De). Hypoxic ventilatory response (HVR) was also determined. At both Post and De, significant increases from Pre were found in HVR at rest and in ventilatory equivalent for O2(V˙e/V˙o 2) and SaO2 during submaximal exercise. There were significant correlations among the changes in HVR at rest and inV˙e/V˙o 2 and SaO2 during hypoxic exercise during intermittent hypoxia. We conclude that 1 wk of daily exposure to 1 h of hypoxia significantly improved oxygenation in exercise during subsequent acute hypoxic exposures up to 1 wk after the conditioning, presumably caused by the enhanced hypoxic ventilatory chemosensitivity.

scholarly journals Clinico-Pathological Findings of Bangladeshi Covid 19 Patients with their Clinical Outcome: Study of A Cohort of 201 Cases

2020 ◽  
pp. 37-42
Author(s):  
Nasir Uddin Ahmed ◽  
Md Azizul Islam ◽  
Md Anwarul Kabir ◽  
Md Habibur Rahman ◽  
SM Anwar Sadat
Keyword(s):  
Clinical Outcome ◽  
Respiratory Distress ◽  
Sore Throat ◽  
Respiratory System ◽  
Clinical Presentation ◽  
Severe Disease ◽  
Age Groups ◽  
Military Hospital ◽  
Human Beings ◽  
History Of

Introduction: COVID-19 is a major threat to human beings. Clinical characterization, rapid identification of cases and isolation are vital for containments of rapidly spreading disease. The objectives of the study were to evaluate the clinico pathologic profile of Covid 19 positive Bangladeshi patients and also to see their clinical outcome within defined period. Methods: This cohort study on 201 Bangladeshi cases was done in Combined Military Hospital, a tertiary level hospital in Dhaka, Bangladesh from April 2020 to May 2020. Total 201 COVID-19 cases were enrolled after getting the result positive for RT-PCR. After collection, data were analysed to show the characteristics of Covid 19 and their outcome after treatment. Results: Among 201 cases, 180 (90%) were male and 21 (10%) were female. The most prevalent affected age groups were 71 (35.5%) patients in 26-35 years age, 54 (27%) in 16- 25 years, 49 (24.5%) in 35-45 years. Mean age is 32.2±2. Among the total cases, 146 (73%) have positive history of contact, 37 (18.5%) have no history of any contact, 8 (4%) denied any contact with COVID-19 patients. Regarding clinical presentations, 67 (33.5%) patients presented with only one symptoms, 125 (62.5%) had multiple symptoms and 9 (4.5%) cases were asymptomatic. 154 (77%) patients presented with fever. Other presentations were cough 71 (35.5%), headache 27 (13.5%), myalgia 25 (12.5%), sore throat 25 (12.5%), malaise 15 (7.5%), respiratory distress 11 (5.5%). Respiratory system was the dominant domain of clinical presentation. Leukopenia was presented by 12 patients and 12 had lymphopenia. 18 patients had mild thrombocytopenia. Pulse oxymetry showed oxygen saturation below 88% in 12 cases. After oxygen therapy 7 cases were improved and 5 cases were shifted to Corona ICU as their saturation fell below 70. These 5 patients are categorised as severe disease, rest 196 patients were mild in nature. Conclusion: COVID 19 affects male more than female. Common symptoms are fever, cough, headache, myalgia, sore throat, malaise, respiratory distress. Respiratory system is the dominant domain of clinical presentation. ICU support was needed in 2.5 % cases and death rate was 1% which was associated with comorbidity of CKD. J Bangladesh Coll Phys Surg 2020; 38(0): 37-42

A model for the relation between respiratory neural and mechanical outputs. II. Methods

1981 ◽  
Vol 51 (4) ◽  
pp. 979-989 ◽  
Author(s):  
W. Riddle ◽  
M. Younes
Keyword(s):  
Theoretical Analysis ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Muscle Activation ◽  
Indirect Evidence ◽  
Present Communication ◽  
Inspiratory Muscles ◽  
Flow Profiles ◽  
Preceding Communication ◽  
Pressure Output

In the preceding communication we developed a model for the conversion of neural output to mechanical output. We were left with two qualitative uncertainties, namely, the relation between neural output and isometric pressure, and the behavior of inspiratory muscles during expiratory flow; and two quantitative uncertainties concerning the effect of configurational pathway on pressure output, and the slope of the pressure-flow relation. For each of the above uncertainties we made certain assumptions based on indirect evidence but defined reasonable error limits. In the present communication we describe the method of implementing the model and evaluate the significance, in terms of spirometric output, of possible errors in the assumptions. Volume and flow profiles were generated from different neural output profiles. Analysis was repeated when the different assumptions were systematically altered within the limits set by the previous theoretical analysis. We conclude that the pattern of inspiratory muscle activation during spontaneous breathing and the existence of several mechanical interactions within the respiratory system combine to render spirometric output fairly insensitive to most potential errors in our assumptions.

Digital Simulation of the Chemical Control of Ventilation

1973 ◽  
Vol 95 (3) ◽  
pp. 335-339
Author(s):  
H. T. Milhorn ◽  
W. J. Reynolds
Keyword(s):  
Computer Model ◽  
Respiratory System ◽  
Digital Computer ◽  
Chemical Control ◽  
Minute Ventilation ◽  
Digital Simulation ◽  
Transient Responses ◽  
O2 Concentration ◽  
Lower Oxygen ◽  
Series Of Experiments

Experimental human data, obtained for the development and evaluation of a digital computer model of the human respiratory system, are presented. The data are from two series of experiments. In the first series the transient responses of tidal volume, respiratory frequency, minute ventilation, alveolar Pco2 and alveolar Po2 were obtained for several inspired CO2 concentrations (3, 5, 6, and 7 percent). In the second series, transient responses of the same variables were obtained for steps of inspired O2 concentration from room air to several lower oxygen levels (9, 8, and 7 percent). An example of the use of the data for the development and evaluation of a model is indicated.

Sign in / Sign up

Export Citation Format

Share Document