O<sub>2</sub>-CO<sub>2</sub> diagram as a tool for comprehension of blood gas abnormalities

Subramani, Sathya; Kanthakumar, Praghalathan; Maneksh, Delinda; Sidharthan, Anita; Rao, Shoma V.; Parasuraman, Vinodh; Tharion, Elizabeth

doi:10.1152/advan.00110.2010

Cited by 6 publications

(2 citation statements)

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“…The O 2 difference in this hypothesis is based on the estimation of PETO 2 ‐PaO 2 with the aid of standard bedside monitored parameters. It is well‐known that the O 2 difference (PIO 2 ‐PETO 2 ) is approximately PETCO 2, providing an estimate for PETO 2 (PIO 2 ‐PETCO 2 ) 12 …”

Section: Methodsmentioning

confidence: 99%

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

Rentola

Skrifvars

Heinonen

et al. 2020

Acta Anaesthesiol Scand

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Background Controlling arterial carbon dioxide is paramount in mechanically ventilated patients, and an accurate and continuous noninvasive monitoring method would optimize management in dynamic situations. In this study, we validated and further refined formulas for estimating partial pressure of carbon dioxide with respiratory gas and pulse oximetry data in mechanically ventilated cardiac arrest patients. Methods A total of 4741 data sets were collected retrospectively from 233 resuscitated patients undergoing therapeutic hypothermia. The original formula used to analyze the data is PaCO2‐est1 = PETCO2 + k[(PIO2 − PETCO2) − PaO2]. To achieve better accuracy, we further modified the formula to PaCO2‐est2 = k1*PETCO2 + k2*(PIO2 − PETCO2) + k3*(100‐SpO2). The coefficients were determined by identifying the minimal difference between the measured and calculated arterial carbon dioxide values in a development set. The accuracy of these two methods was compared with the estimation of the partial pressure of carbon dioxide using end‐tidal carbon dioxide. Results With PaCO2‐est1, the mean difference between the partial pressure of carbon dioxide, and the estimated carbon dioxide was 0.08 kPa (SE ±0.003); with PaCO2‐est2 the difference was 0.036 kPa (SE ±0.009). The mean difference between the partial pressure of carbon dioxide and end‐tidal carbon dioxide was 0.72 kPa (SE ±0.01). In a mixed linear model, there was a significant difference between the estimation using end‐tidal carbon dioxide and PaCO2‐est1 (P < .001) and PaCO2‐est2 (P < .001) respectively. Conclusions This novel formula appears to provide an accurate, continuous, and noninvasive estimation of arterial carbon dioxide.

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Section: Methodsmentioning

confidence: 99%

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

Rentola

Skrifvars

Heinonen

et al. 2020

Acta Anaesthesiol Scand

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“…As inspired humidified gas moves from the trachea into the lungs, a fourth gas is added as CO2 diffuses into the mix. In mammals, the partial pressure of alveolar oxygen at steady state, is predicted by the alveolar gas equation (Subramani S, et al, 2011). There is a small added factor which affects the final value of PAO2 by less than 1% so the simplified equation is usually used:…”

Section: Methodsmentioning

confidence: 99%

The alveolar gas equation: do lessons from WW2 research into high flying pilots provide insights into the adaptation to high altitude flight in birds?

Seear

2020

Preprint

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Dalton's law of partial pressures applies equally to birds and mammals so, as gas moves from the nostrils to the smallest gas-diffusion airways, the sequential addition of water vapour and CO2, steadily reduce the partial pressure of O2 (PO2) within the gas mixture. The PO2, at the point of gas exchange, at sea level, will be about 60 mm Hg less than the original PO2 within atmospheric air. As a result, the inspired PO2 is an inaccurate starting point for any model of oxygen transport. In humans, the interactions of gases at the point of diffusion, is described and quantified by the Alveolar Gas Equation (AGE). Its development during WW2, provided valuable insights into human gas exchange and also into the responses to high altitude flight in pilots but, except for an early study of hypoxia in pigeons, the AGE is not mentioned in the avian literature. Even detailed models of oxygen transport in birds omit the effect of CO2 clearance on pulmonary oxygen transfer. This paper develops two related arguments concerning the application of the AGE to birds. The first is that avian blood gas predictions, based on the theory of multicapillary serial arterialization (MSA), are inaccurate because they do not account for the added partial pressure of diffused CO2. The second is that the primary adaptation to hypobaric hypoxia is the same for both classes and consists of defending PaO2 by reducing PaCO2 through increasing hyperventilation. Support for the first is demonstrated by comparing PaO2 predictions made using the AGE, with published values from avian studies and also against values predicted by the theory of MSA.The second is illustrated by comparing the results of high altitude studies of both birds and humans. The application of the AGE to avian respiratory physiology would improve the predictive accuracy of models of the O2 cascade and would also provide better insights into the primary adaptation to high altitude flight.Introduction.

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A School Goes into Depth

Ferretti

2023

Perspectives in Physiology

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O₂-CO₂ diagram as a tool for comprehension of blood gas abnormalities

Cited by 6 publications

References 4 publications

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

The alveolar gas equation: do lessons from WW2 research into high flying pilots provide insights into the adaptation to high altitude flight in birds?

A School Goes into Depth

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O2-CO2 diagram as a tool for comprehension of blood gas abnormalities

Cited by 6 publications

References 4 publications

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post‐resuscitation care

The alveolar gas equation: do lessons from WW2 research into high flying pilots provide insights into the adaptation to high altitude flight in birds?

A School Goes into Depth

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O₂-CO₂ diagram as a tool for comprehension of blood gas abnormalities