Infrared end-tidal CO2 measurement does not accurately predict arterial CO2 values or end-tidal to arterial PCO2, gradients in rabbits with lung injury

The steady-state end-tidal CO2 tension (PCO2) was examined during control and 1% CO2 inhalation periods in awake beagle dogs with an intact airway breathing through a low dead-space respiratory mask. A total of eight experiments were performed in four dogs, comprising 31 control observations and 23 CO2 inhalation observations. The 1% inhaled CO2 produced a significant increase in the steady-state end-tidal PCO2 comparable to the expected 1 Torr predicted from conventional CO2 control of ventilation. We conclude that 1% inhaled CO2 results in a hypercapnia. Any protocol that is to resolve the question of whether mechanisms are acting during low levels of inhaled CO2 such that ventilation increases without any change in arterial PCO2 must have sufficient resolving power to discriminate changes in gas tension in magnitude predicted from conventional (i.e., arterial PCO2) control of ventilation.

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Mass spectrometry for monitoring respiratory and anesthetic gas waveforms in rats

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.2.955 ◽

1988 ◽

Vol 65 (2) ◽

pp. 955-963 ◽

Cited By ~ 8

Author(s):

D. R. Larach ◽

H. G. Schuler ◽

T. M. Skeehan ◽

J. A. Derr

Keyword(s):

Mass Spectrometric ◽

Laboratory Animals ◽

Sprague Dawley ◽

Arterial Pco2 ◽

Sprague Dawley Rats ◽

Reflex Movement ◽

The Difference ◽

End Tidal ◽

Respiratory Gases ◽

End Tidal Co2

A method is presented for real-time monitoring of airway gas concentration waveforms in rats and other small animals. Gas is drawn from the tracheal tube, analyzed by a mass spectrometer, and presented as concentration vs. time waveforms simultaneously for CO2, halothane, and other respiratory gases and anesthetics. By use of a respiratory simulation device, the accuracy of mass spectrometric end-tidal CO2 analysis was compared with both the actual gas composition and infrared spectrophotometry. The effects of various ventilator rates and inspiration-to-expiration ratios on sampling accuracy were also examined. The technique was validated in male Sprague-Dawley rats being ventilated mechanically. The difference between the arterial PCO2 (PaCO2) and the end-tidal PCO2 (PETCO2) was not significantly different from zero, and the correlation between PETCO2 and PaCO2 was strong (r = 0.97, P less than 0.0001). Continuous gas sampling for periods up to 5 min did not affect PaCO2, PETCO2, or airway pressures. By use of this new method for measuring end-tidal halothane concentrations in rats approximately 6.5 mo of age, the minimum alveolar concentration of halothane that prevented reflex movement in response to tail clamping was 0.97 +/- 0.04% atmospheric (n = 14). This mass spectrometric technique can be used in small laboratory animals, such as rats, weighing as little as 250 g. Gas monitoring did not distort either PETCO2 or PaCO2. Under the defined conditions of this study, accurate and simultaneous measurements of phasic respiratory concentrations of anesthetic and respiratory gases can be achieved.

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Single breath end-tidal CO2 estimates of arterial PCO2 in infants and children

Canadian Journal of Anesthesia/Journal canadien d anesthésie ◽

10.1007/bf03011429 ◽

1989 ◽

Vol 36 (2) ◽

pp. 110-112 ◽

Cited By ~ 17

Author(s):

B. Bissonnette ◽

J. Lerman

Keyword(s):

Infants And Children ◽

Arterial Pco2 ◽

Single Breath ◽

End Tidal ◽

End Tidal Co2 ◽

In Infants And Children

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Breathing responses of unanesthetized man and guinea pigs to increased transrespiratory pressure

Journal of Applied Physiology ◽

10.1152/jappl.1979.47.1.119 ◽

1979 ◽

Vol 47 (1) ◽

pp. 119-125 ◽

Cited By ~ 7

Author(s):

J. R. Gillespie ◽

E. Bruce ◽

J. Alexander ◽

J. Mead

Keyword(s):

Lung Volume ◽

Guinea Pigs ◽

The Body ◽

Low Frequencies ◽

Lung Inflation ◽

Arterial Pco2 ◽

The Face ◽

Mechanical Factors ◽

End Tidal ◽

End Tidal Co2

We compared the breathing responses of unanesthetized men and guinea pigs to externally imposed shifts in lung volume produced by steady pressures applied to the body surface while the mouth remained near atmospheric pressure. Lung inflation caused no consistent or significant changes either in frequency or end-tidal CO2 in the three men. In contrast, during lung inflation the guinea pigs breathed at low frequencies and smaller tidal volumes and showed consistent increases in arterial PCO2 lasting up to 10 min. The changes seen immediately on application of pressure, namely apneic periods followed by breathing in which inspiratory duration was shortened while expiratory duration was substantially increased, indicates that conscious guinea pigs have active inflation reflexes. We concluded that the reflex responses rather than mechanical factors probably account for the underventilation in the guinea pigs and that guinea pigs are not nearly as well equipped as is man to defend gas exchange in the face of nonmetabolic shifts in lung volume.

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Comparison of end-tidal CO2 measured by transportable capnometer (EMMA™ capnograph) and arterial pCO2 in general anesthesia

Journal of Clinical Monitoring and Computing ◽

10.1007/s10877-015-9748-x ◽

2015 ◽

Vol 30 (5) ◽

pp. 737-741 ◽

Cited By ~ 6

Author(s):

Kyung Woo Kim ◽

Hey Ran Choi ◽

Si Ra Bang ◽

Jeong-wook Lee

Keyword(s):

General Anesthesia ◽

Arterial Pco2 ◽

End Tidal ◽

End Tidal Co2

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Cardiorespiratory Functioning in Youth with Persistent Post-Concussion Symptoms: A Pilot Study

Journal of Clinical Medicine ◽

10.3390/jcm10040561 ◽

2021 ◽

Vol 10 (4) ◽

pp. 561

Author(s):

Aliyah Snyder ◽

Christopher Sheridan ◽

Alexandra Tanner ◽

Kevin Bickart ◽

Molly Sullan ◽

...

Keyword(s):

Processing Speed ◽

Mean Value ◽

Exhaled Breath ◽

Post Injury ◽

The Past ◽

Neurobehavioral Outcomes ◽

End Tidal ◽

Relationship Of ◽

The Relationship ◽

End Tidal Co2

Dysregulation of the autonomic nervous system (ANS) may play an important role in the development and maintenance of persistent post-concussive symptoms (PPCS). Post-injury breathing dysfunction, which is influenced by the ANS, has not been well-studied in youth. This study evaluated cardiorespiratory functioning at baseline in youth patients with PPCS and examined the relationship of cardiorespiratory variables with neurobehavioral outcomes. Participants were between the ages of 13–25 in two groups: (1) Patients with PPCS (concussion within the past 2–16 months; n = 13) and (2) non-injured controls (n = 12). Capnometry was used to obtain end-tidal CO2 (EtCO2), oxygen saturation (SaO2), respiration rate (RR), and pulse rate (PR) at seated rest. PPCS participants exhibited a reduced mean value of EtCO2 in exhaled breath (M = 36.3 mmHg, SD = 2.86 mmHg) and an altered inter-correlation between EtCO2 and RR compared to controls. Neurobehavioral outcomes including depression, severity of self-reported concussion symptoms, cognitive catastrophizing, and psychomotor processing speed were correlated with cardiorespiratory variables when the groups were combined. Overall, results from this study suggest that breathing dynamics may be altered in youth with PPCS and that cardiorespiratory outcomes could be related to a dimension of neurobehavioral outcomes associated with poorer recovery from concussion.

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