Anesth Analg
From the Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts.
Published: July 2018
Background: The accurate measurement of oxygen consumption (VO2) and energy expenditure (EE) may be helpful to optimize the treatment of critically ill patients. However, current techniques are limited in their ability to accurately quantify these end points in infants due to a low VO2, low tidal volume, and rapid respiratory rate. This study describes and validates a new device intended to perform in this size range.
Methods: We created a customized device that quantifies inspiratory volume using a pneumotachometer and concentrations of oxygen and carbon dioxide gas in the inspiratory and expiratory limbs. We created a customized algorithm to achieve precise time alignment of these measures, incorporating bias flow and compliance factors. The device was validated in 3 ways. First, we infused a certified gas mixture (50% oxygen/50% carbon dioxide) into an artificial lung circuit, comparing measured with simulated VO2 and carbon dioxide production (VCO2) within a matrix of varying tidal volume (4-20 mL), respiratory rate (20-80 bpm), and fraction of inspired oxygen (0.21-0.8). Second, VO2, VCO2, and EE were measured in Sprague Dawley rats under mechanical ventilation and were compared to simultaneous Douglas bag collections. Third, the device was studied on n = 14 intubated, spontaneously breathing neonates and infants, comparing measured values to Douglas measurements. In all cases, we assessed for difference between the device and reference standard by linear regression and Bland-Altman analysis.
Results: In vitro, the mean ± standard deviation difference between the measured and reference standard VO2 was +0.04 ± 1.10 (95% limits of agreement, -2.11 to +2.20) mL/min and VCO2 was +0.26 ± 0.31 (-0.36 to +0.89) mL/min; differences were similar at each respiratory rate and tidal volume measured, but higher at fraction of inspired oxygen of 0.8 than at 0.7 or lower. In rodents, the mean difference was -0.20 ± 0.55 (-1.28 to +0.89) mL/min for VO2, +0.16 ± 0.25 (-0.32 to +0.65) mL/min for VCO2, and -0.84 ± 3.29 (-7.30 to +5.61) kcal/d for EE. In infants, the mean VO2 was 9.0 ± 2.5 mL/kg/min by Douglas method and was accurately measured by the device (bias, +0.22 ± 0.87 [-1.49 to +1.93] mL/kg/min). The average VCO2 was 8.1 ± 2.3 mL/kg/min, and the device exhibited a bias of +0.33 ± 0.82 (-1.27 to +1.94) mL/kg/min. Mean bias was +2.56% ± 11.60% of the reading for VO2 and +4.25% ± 11.20% of the reading for VCO2; among 56 replicates, 6 measurements fell outside of the 20% error range, and no patient had >1 of 4 replicates with a >20% error in either VO2 or VCO2.
Conclusions: This device can measure VO2, VCO2, and EE with sufficient accuracy for clinical decision-making within the neonatal and pediatric size range, including in the setting of tachypnea or hyperoxia.
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http://dx.doi.org/10.1213/ANE.0000000000003308 | DOI Listing |
Pulmonology
December 2025
Sorbonne Université, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France.
Background: Nasal high flow (NHF) has been proposed to sustain high intensity exercise in people with COPD, but we have a poor understanding of its physiological effects in this clinical setting.
Research Question: What is the effect of NHF during exercise on dynamic respiratory muscle function and activation, cardiorespiratory parameters, endurance capacity, dyspnoea and leg fatigue as compared to control intervention.
Study Design And Methods: Randomized single-blind crossover trial including COPD patients.
Front Pediatr
January 2025
The Ritchie Centre, Hudson Institute of Medical Research, Clayton VIC, Australia.
Introduction: As airway liquid is cleared into lung interstitial tissue after birth, the chest wall must expand to accommodate this liquid and the incoming air. We examined the effect of applying external positive and negative pressures to the chest wall on lung aeration in near-term rabbit kittens at risk of developing respiratory distress.
Methods: Rabbit kittens (30 days; term ∼31 days) were randomised into and groups.
Br J Anaesth
February 2025
CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain; Intensive Care Unit, Hospital Universitario La Princesa, Madrid, Spain.
Despite the maturity and sophistication of anaesthesia workstations, improvements in our understanding of intraoperative mechanical ventilation, and use of less invasive surgical techniques, postoperative pulmonary complications (PPCs) are still a common problem in surgical patients of all ages. PPCs are associated with a higher incidence of perioperative morbidity and mortality, longer hospital stays, and higher healthcare costs. PPCs are strongly associated with anaesthesia-induced atelectasis, which predisposes to lung damage when partially collapsed lungs are subjected to mechanical ventilation.
View Article and Find Full Text PDFAm J Vet Res
January 2025
National Taiwan University Veterinary Hospital, National Taiwan University, Taipei, Taiwan.
Objective: Enhancing ventilatory effort during pulmonary function testing can help reveal flow limitations not evident in normal tidal breathing. This study aimed to assess the efficacy and tolerability of using a CO2/O2 gas mixture to enhance tidal breathing with a barometric whole-body plethysmography system in both healthy cats and those with feline lower airway disease (FLAD).
Methods: This prospective study included healthy cats and those with FLAD, which underwent pulmonary function testing and were exposed to a 10% CO2/90% O2 gas mixture in a barometric whole-body plethysmography chamber, with CO2 concentrations maintained within the target range of 5% to 10%.
Adv Clin Exp Med
January 2025
Clinic of Children's Diseases, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Lithuania.
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Material And Methods: The case-control study was conducted from December 2020 to April 2021.
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