Effect of positive-pressure breathing on cardiovascular and thermoregulatory responses to exercise

1985 ◽  
Vol 58 (3) ◽  
pp. 876-881 ◽  
Author(s):  
N. B. Vroman ◽  
W. S. Beckett ◽  
S. Permutt ◽  
S. Fortney
Keyword(s):  
Airway Pressure ◽  
Forearm Blood Flow ◽  
Positive Airway Pressure ◽  
Cycle Ergometer ◽  
Positive Pressure ◽  
Esophageal Temperature ◽  
Healthy Male ◽  
O2 Uptake ◽  
Warm Environment ◽  
Ergometer Exercise

Five healthy male volunteers performed 20 min of both seated and supine cycle-ergometer exercise (intensity, 50% maximal O2 uptake) in a warm environment (Tdb = 30 degrees C, relative humidity = 40–50%) with and without breathing 10 cmH2O of continuous positive airway pressure (CPAP). The final esophageal temperature (Tes) at the end of 20 min of seated exercise was significantly higher during CPAP (mean difference = 0.18 +/- 0.04 degree C, P less than 0.05) compared with control breathing (C). The Tes threshold for forearm vasodilation was significantly higher (P less than 0.05) during seated CPAP exercise than C (C = 37.16 +/- 0.13 degrees C, CPAP = 37.38 + 0.12 degree C). The highest forearm blood flow (FBF) at the end of exercise was significantly lower (P less than 0.05) during seated exercise with CPAP (mean +/- SE % difference from C = -30.8 +/- 5.8%). During supine exercise, there were no significant differences in the Tes threshold, highest FBF, or final Tes with CPAP compared with C. The added strain on the cardiovascular system produced by CPAP during seated exercise in the heat interacts with body thermoregulation as evidenced by elevated vasodilation thresholds, reduced peak FBF, and slightly higher final esophageal temperatures.

Method for computing the oxidation of two 13C-substrates ingested simultaneously during exercise

1993 ◽  
Vol 75 (3) ◽  
pp. 1419-1422 ◽  
Author(s):  
F. Peronnet ◽  
E. Adopo ◽  
D. Massicotte ◽  
G. R. Brisson ◽  
C. Hillaire-Marcel
Keyword(s):  
Prolonged Exercise ◽  
Cycle Ergometer ◽  
Healthy Male ◽  
O2 Uptake ◽  
Oxidation Rates ◽  
Exogenous Glucose ◽  
Ergometer Exercise ◽  
The Difference ◽  
Endogenous Substrates ◽  
Male Subjects

This study presents a method for computing the respective amounts of two simultaneously ingested exogenous substrates (A and B) that are oxidized during a period of prolonged exercise by use of 13C labeling. This method is based on the observation that the total volume of 13CO2 produced (V13CO2tot) is the sum of 1) V13CO2 arising from the oxidation of endogenous substrates (V13CO2endo), 2) V13CO2 arising from the oxidation of substrate A (V13CO2A), and 3) V13CO2 arising from the oxidation of substrate B (V13CO2B). The equation, V13CO2tot = V13CO2endo+V13CO2A+V13CO2B, with three unknowns, can be solved from the results of three experiments conducted under the same conditions but with at least two values for the isotopic composition of A and B. This method has been used on five healthy male subjects to compute the amounts of glucose and fructose oxidized when a mixture of 15 g of glucose and 15 g of fructose is ingested (in 300 ml of water) over 60 min of cycle ergometer exercise at 65% of maximal O2 uptake. Results from three experiments indicated that 9.8 +/- 3.1 and 5.7 +/- 2.1 g of glucose and fructose, respectively, were oxidized. The total amount of exogenous carbohydrates oxidized (15.5 +/- 4.3 g) is in agreement with the oxidation rates of exogenous glucose computed in similar conditions when 30 g of glucose were ingested (13 g; Peronnet et al. Med. Sci. Sports Exercise 25: 297–302, 1993). The difference between the oxidation rates of exogenous glucose and fructose is also in line with data from the literature.

Nasal Intermittent Positive Pressure Ventilation versus Continuous Positive Airway Pressure and Apnea of Prematurity: A Systematic Review and Meta-Analysis

2021 ◽  
Author(s):  
Bayane Sabsabi ◽  
Ava Harrison ◽  
Laura Banfield ◽  
Amit Mukerji
Keyword(s):  
Systematic Review ◽  
Continuous Positive Airway Pressure ◽  
Airway Pressure ◽  
Primary Outcome ◽  
Positive Pressure Ventilation ◽  
Positive Airway Pressure ◽  
Meta Analysis ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Apnea Of Prematurity

Objective The study aimed to systematically review and analyze the impact of nasal intermittent positive pressure ventilation (NIPPV) versus continuous positive airway pressure (CPAP) on apnea of prematurity (AOP) in preterm neonates. Study Design In this systematic review and meta-analysis, experimental studies enrolling preterm infants comparing NIPPV (synchronized, nonsynchronized, and bi-level) and CPAP (all types) were searched in multiple databases and screened for the assessment of AOP. Primary outcome was AOP frequency per hour (as defined by authors of included studies). Results Out of 4,980 articles identified, 18 studies were included with eight studies contributing to the primary outcome. All studies had a high risk of bias, with significant heterogeneity in definition and measurement of AOP. There was no difference in AOPs per hour between NIPPV versus CPAP (weighted mean difference = −0.19; 95% confidence interval [CI]: −0.76 to 0.37; eight studies, 456 patients). However, in a post hoc analysis evaluating the presence of any AOP (over varying time periods), the pooled odds ratio (OR) was lower with NIPPV (OR: 0.46; 95% CI: 0.32–0.67; 10 studies, 872 patients). Conclusion NIPPV was not associated with decrease in AOP frequency, although demonstrated lower odds of developing any AOP. However, definite recommendations cannot be made based on the quality of the published evidence. Key Points

Care of the Neonate on Nasal Continuous Positive Airway Pressure: A Bedside Guide

2018 ◽  
Vol 37 (1) ◽  
pp. 24-32
Author(s):  
Jennifer M. Guay ◽  
Dru Carvi ◽  
Deborah A. Raines ◽  
Wendy A. Luce
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Respiratory Distress ◽  
Parent Education ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Clinical Manifestations ◽  
Neonatal Morbidity ◽  
Intermittent Positive Pressure Ventilation ◽  
Positive Pressure ◽  
Team Approach

Respiratory distress continues to be a major cause of neonatal morbidity. Current neonatal practice recommends the use of nasal continuous positive airway pressure (nCPAP) in the immediate resuscitation and continued support of neonates of all gestations with clinical manifestations of respiratory distress. Despite the many short- and long-term benefits of nCPAP, many neonatal care units have met resistance in its routine use. Although there have been numerous recent publications investigating the use and outcomes of various modes of nCPAP delivery, surfactant administration, mechanical ventilation, and other forms of noninvasive respiratory support (high-flow nasal cannula, nasal intermittent positive pressure ventilation), there has been a relative lack of publications addressing the practical bedside care of infants managed on nCPAP. Effective use of nCPAP requires a coordinated interprofessional team approach, ongoing assessment of the neonate, troubleshooting the nCPAP circuit, and parent education.

Influence of graded dehydration on hyperthermia and cardiovascular drift during exercise

1992 ◽  
Vol 73 (4) ◽  
pp. 1340-1350 ◽  
Author(s):  
S. J. Montain ◽  
E. F. Coyle
Keyword(s):  
Blood Flow ◽  
Prolonged Exercise ◽  
Forearm Blood Flow ◽  
Sweat Rate ◽  
Sodium Concentration ◽  
O2 Consumption ◽  
Esophageal Temperature ◽  
Warm Environment ◽  
Cardiovascular Drift ◽  
Highly Correlated

This investigation determined the effect of different rates of dehydration, induced by ingesting different volumes of fluid during prolonged exercise, on hyperthermia, heart rate (HR), and stroke volume (SV). On four different occasions, eight endurance-trained cyclists [age 23 +/- 3 (SD) yr, body wt 71.9 +/- 11.6 kg, maximal O2 consumption 4.72 +/- 0.33 l/min] cycled at a power output equal to 62-67% maximal O2 consumption for 2 h in a warm environment (33 degrees C dry bulb, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or ingested a small (SF), moderate (MF), or large (LF) volume of fluid that replaced 20 +/- 1, 48 +/- 1, and 81 +/- 2%, respectively, of the fluid lost in sweat during exercise. The protocol resulted in graded magnitudes of dehydration as body weight declined 4.2 +/- 0.1, 3.4 +/- 0.1, 2.3 +/- 0.1, and 1.1 +/- 0.1%, respectively, during NF, SF, MF, and LF. After 2 h of exercise, esophageal temperature (Tes), HR, and SV were significantly different among the four trials (P < 0.05), with the exception of NF and SF. The magnitude of dehydration accrued after 2 h of exercise in the four trials was linearly related with the increase in Tes (r = 0.98, P < 0.02), the increase in HR (r = 0.99, P < 0.01), and the decline in SV (r = 0.99, P < 0.01). LF attenuated hyperthermia, apparently because of higher skin blood flow, inasmuch as forearm blood flow was 20–22% higher than during SF and NF at 105 min (P < 0.05). There were no differences in sweat rate among the four trials. In each subject, the increase in Tes from 20 to 120 min of exercise was highly correlated to the increase in serum osmolality (r = 0.81-0.98, P < 0.02-0.19) and the increase in serum sodium concentration (r = 0.87-0.99, P < 0.01-0.13) from 5 to 120 min of exercise. In summary, the magnitude of increase in core temperature and HR and the decline in SV are graded in proportion to the amount of dehydration accrued during exercise.

Ventilatory responses to the metabolic acidosis of treadmill and cycle ergometry

1976 ◽  
Vol 40 (6) ◽  
pp. 864-867 ◽  
Author(s):  
S. N. Koyal ◽  
B. J. Whipp ◽  
D. Huntsman ◽  
G. A. Bray ◽  
K. Wasserman
Keyword(s):  
Metabolic Acidosis ◽  
Treadmill Exercise ◽  
Cycle Ergometer ◽  
Cycle Ergometry ◽  
O2 Uptake ◽  
Ventilatory Responses ◽  
Arterial Ph ◽  
Ergometer Exercise ◽  
Type Of Exercise ◽  
Relationship Of

Ventilation and acid-base responses were studied at comparable levels of O2 uptake during cycle ergometer and treadmill exercise, to determine the extent to which the type of exercise affects these responses. Twenty male subjects performed 50-, 100-, and 150-W cycle ergometer exercise and three work rates of similar O2 uptake on a treadmill. At comparable oxygen uptakes, arterial lactate and VE were higher and arterial pH and bicarbonate were lower for cycle ergometer than treadmill exercise. These differences could be accounted for by the greater degree of metabolic acidosis during cycle ergometer work. The increment in VE over that predicted (from an extrapolation of the linear relationship of the VE-VO2 relationship for low work rates) was linearly related to the decrease in arterial bicarbonate; VE was increased by approximately 4 1/min for each meq/1 of bicarbonate decrease for both treadmill and cycle ergometry.

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