Response time of indirectly accessed gas exchange depends on measurement method

2018 ◽  
Vol 63 (6) ◽  
pp. 647-655 ◽  
Author(s):  
Jakub Rafl ◽  
Filip Kulhanek ◽  
Petr Kudrna ◽  
Vaclav Ort ◽  
Karel Roubik
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Response Time ◽  
Partial Pressure ◽  
Sudden Change ◽  
Lung Ventilation ◽  
Carbon Dioxide Partial Pressure ◽  
Gas Mixture ◽  
Noninvasive Methods ◽  
Transcutaneous Oxygen

Abstract Noninvasive techniques are routinely used for assessment of tissue effects of lung ventilation. However, comprehensive studies of the response time of the methods are scarce. The aim of this study was to compare the response time of noninvasive methods for monitoring of gas exchange to sudden changes in the composition of the inspired gas. A prospective experimental study with 16 healthy volunteers was conducted. A ventilation circuit was designed that enabled a fast change in the composition of the inspiratory gas mixture while allowing spontaneous breathing. The volunteers inhaled a hypoxic mixture, then a hypercapnic mixture, a hyperoxic mixture and finally a 0.3% CO mixture. The parameters with the fastest response to the sudden change of O2 in inhaled gas were peripheral capillary oxygen saturation (SpO2) and regional tissue oxygenation (rSO2). Transcutaneous oxygen partial pressure (tcpO2) had almost the same time of reaction, but its time of relaxation was 2–3 times longer. End-tidal carbon dioxide (EtCO2) response time to change of CO2 concentration in inhaled gas was less than half in comparison with transcutaneous carbon dioxide partial pressure (tcpCO2). All the examined parameters and devices reacted adequately to changes in gas concentration in the inspiratory gas mixture.

The behaviour of plants in various gas mixtures

1971 ◽  
Vol 179 (1056) ◽  
pp. 177-188
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Higher Plants ◽  
Dry Mass ◽  
Carbon Dioxide Partial Pressure ◽  
Ambient Oxygen ◽  
Leaf Dry Mass ◽  
Rate Of Photosynthesis ◽  
Effect Of Oxygen

The effects of the composition and pressure of the ambient gas mixture on the diffusive gas exchange of leaves, and the effects of carbon dioxide and oxygen on respiration and photosynthesis are described. When photosynthesis is limited by the rate at which carbon dioxide reaches the chloroplasts, the net rate of photosynthesis of many (but not all) plant species depends on the ambient oxygen partial pressure. The effect of oxygen may be principally to stimulate a respiratory process rather than to inhibit carboxylation. However, when photosynthesis is not limited by the carbon dioxide supply, this respiratory process seems to be suppressed. The gas exchange of plant communities responds to the aerial environment in the way expected from measurements on single leaves, but the growth response to a given difference in gas composition is smaller than expected because of adaptation, notably in the ratio of leaf dry mass to leaf area. It is concluded that the growth rate of higher plants in given illumination will be independent of the partial pressure of oxygen and of other gases likely to be used to dilute it, provided that the carbon dioxide partial pressure is so adjusted (probably to not more than 2 mbar (200 Pa)) that the rate of photosynthesis is not limited by the rate of diffusion to the chloroplasts.

scholarly journals Second-generation laryngeal mask airway as an alternative to endotracheal tube during prolonged laparoscopic abdominal surgery: a comparative analysis of intraoperative gas exchanges

2021 ◽  
Author(s):  
S Park ◽  
JE Lee ◽  
GS Choi ◽  
JM Kim ◽  
JS Ko ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Laryngeal Mask Airway ◽  
Abdominal Surgery ◽  
Partial Pressure ◽  
Endotracheal Tube ◽  
Second Generation ◽  
Laryngeal Mask ◽  
Arterial Partial Pressure ◽  
Prolonged Surgery

Introduction: Despite several advantages over endotracheal tube (ETT), laryngeal mask airway (LMA), which is used in emergencies under difficult airway maintenance conditions, is rarely utilized in prolonged surgery. We compared the variables representing intraoperative gas exchange with second-generation LMA and ETT during prolonged laparoscopic abdominal surgery. Methods: Prolonged surgery was defined as a surgery lasting more than 2 h. In total, 394 patients who underwent laparoscopic liver resection via either second-generation LMA or ETT were retrospectively analysed. Parameters including end-tidal pressure of carbon dioxide (ETCO2), tidal volume (TV), respiratory rate (RR), peak inspiratory pressure (PIP), arterial partial pressure of carbon dioxide (PaCO2), pH, and ratio of arterial partial pressure of oxygen to fractional inspired oxygen (PFR) during surgery were compared between the two groups. In addition, the incidence of postoperative pulmonary complications (PPC) including pulmonary aspiration was also compared. Results: The values of ETCO2, TV, RR and PIP during pneumoperitoneum were comparable between the two groups. Although PaCO2 at 2 h after induction was higher in patients with LMA (40.5 vs. 38.5 mmHg, p < 0.001), the pH and PFR values of the two groups were comparable. The incidence of PPC was not different. Conclusion: During prolonged laparoscopic abdominal surgery, the second-generation LMA facilitates adequate intraoperative gas exchange and represents an alternative to ETT.

scholarly journals Massive Subcutaneous Emphysema during Laparoscopic Cholecystectomy

1970 ◽  
Vol 21 (1) ◽  
pp. 77-79
Author(s):  
ASM Moosa ◽  
M Baharul Islam ◽  
Shahina Akther ◽  
M Latifur Rahman ◽  
Nazim Uddin Ahmed
Keyword(s):  
Carbon Dioxide ◽  
Laparoscopic Cholecystectomy ◽  
Partial Pressure ◽  
Subcutaneous Emphysema ◽  
Airway Pressure ◽  
Surgical Techniques ◽  
Lung Ventilation ◽  
Peak Airway Pressure ◽  
Sudden Increase ◽  
Partial Pressure Of Oxygen

Laparoscopic surgical techniques are increasingly being applied to treat cholelithiasis and other indications of gallbladder diseases. These procedures however are not without potential morbidity. Herein we describe two patients treated with laparoscopic cholecystectomy; those cases were complicated with subcutaneous emphysema and hypercarbia per-operatively. After discontinuation of pneumoperitoneum, saturation of partial pressure of oxygen (SpO2) gradually increased with improvement of the neck subcutaneous emphysema, at the same time the lung ventilation also improved. Our findings show that we have to stop pneumoperitoneum or decrease partial pressure of end carbon dioxide level immediately, when we find a sudden increase of the peak airway pressure or decrease SpO2 with subcutaneous emphysema during laparoscopic cholecystectomy.   doi: 10.3329/taj.v21i1.3225 TAJ 2008; 21(1): 77-79

Gas-Exchange Rates in a Small Lake as Determined by the Radon Method

1973 ◽  
Vol 30 (10) ◽  
pp. 1475-1484 ◽  
Author(s):  
Steve Emerson ◽  
Wallace Broecker ◽  
D. W. Schindler
Keyword(s):  
Exchange Rate ◽  
Gas Exchange ◽  
Exchange Rates ◽  
Partial Pressure ◽  
Lake Water ◽  
Radon Concentration ◽  
Natural Waters ◽  
Carbon Dioxide Partial Pressure ◽  
Nitrogen And Phosphorus ◽  
Gas Exchange Rate

The radon method, used previously in ocean-atmosphere systems, is used here to determine the gas-exchange rate between the atmosphere and lake 227 of the Experimental Lakes Area. Fertilization of the lake with nitrogen and phosphorus caused the carbon dioxide partial pressure in the lake water to drop well below atmospheric levels; hence, in order to better understand the carbon budget of the lake, an estimate of the CO2 gas-exchange rate was necessary.To determine gas-exchange rates by measuring radon evasion to the atmosphere the source of radon in the lake water must be dissolved radium. Since the radon concentration in lakes derives not only from the decay of dissolved radium but also from the inflow of radon-rich groundwaters, radium was added to the lake to increase the radon concentration well above this fluctuating background level. Although this procedure was complicated by algal uptake of the radium in the lake (Emerson and Hesslein 1973), we were able to place limits on the gas-exchange rate.Our results indicate that the "stagnant boundary layer" thickness is approximately 300 μ. This value is among the largest observed in natural waters. Using this value and the partial pressure of CO2 in the lake water we have calculated an invasion rate of 17 ± 8 mmoles CO2/m2 day.

Temperature-carbon dioxide partial pressure trends in confined aquifers

1998 ◽  
Vol 145 (1-2) ◽  
pp. 73-89 ◽  
Author(s):  
Anne Coudrain-Ribstein ◽  
Philippe Gouze ◽  
Ghislain de Marsily
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Carbon Dioxide Partial Pressure ◽  
Confined Aquifers
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