Effects of nitrous oxide on end-tidal carbon dioxide measurements in spontaneously breathing patients under general anesthesia

Effects of nitrous oxide (N2O) on minimum alveolar concentration (MAC) of desflurane were studied. For that purpose, 30 dogs were randomly allocated into two groups: desflurane group (GD) and N2O and desflurane group (GDN). GD animals received propofol to intubation, and 11.5V% of desflurane diluted in 100% O2. After 30 minutes, they received electric stimulus and if the animal did not react to stimulus, desflurane concentration was reduced by 1.5V%. This protocol was repeated at each 15 minutes, and stimulus was interrupted when voluntary reaction was observed. GDN dogs were submitted to diluent flow 30% O2 and 70% N2O. Desflurane's MAC; heart (HR) and respiratory (RR) rates; systolic, diastolic and mean arterial pressures (SAP, DAP, and MAP, respectively); end tidal carbon dioxide (ETCO2); oxyhemoglobin saturation (SpO2) and body temperature (T) were evaluated. In both groups increase in HR and ETCO2, and decrease in RR and T were associated with administration of the highest dose of desflurane. Blood pressures decreased 30 minutes after desflurane administration in GDN, and after this measurement the values increased. Reduction in desflurane's MAC was observed as well. It is concluded that N2O associated with desflurane reduced desflurane's MAC by 16% with increase in HR and respiratory depression.

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Relationship between Arterial and End-tidal Carbon Dioxide Tension during General Anesthesia for Caesarean Section

Korean Journal of Anesthesiology ◽

10.4097/kjae.1991.24.5.991 ◽

1991 ◽

Vol 24 (5) ◽

pp. 991

Author(s):

Kyung Bong Yoon ◽

Wyun Kon Park ◽

Hyun Kyo Lim ◽

Dae Ja Um ◽

Ryoung Choi

Keyword(s):

Carbon Dioxide ◽

Caesarean Section ◽

General Anesthesia ◽

Carbon Dioxide Tension ◽

End Tidal Carbon Dioxide ◽

End Tidal

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Changes in Optic Nerve Sheath Diameter in Response to Various Levels of End-Tidal Carbon Dioxide in Healthy Patients under General Anesthesia

Journal of Neuroanaesthesiology and Critical Care ◽

10.1055/s-0038-1654749 ◽

2018 ◽

Vol 05 (02) ◽

pp. 94-97

Author(s):

Indu Kapoor ◽

Ankur Khandelwal ◽

Charu Mahajan ◽

Hemanshu Prabhakar ◽

Parmod Kumar Bithal

Keyword(s):

Carbon Dioxide ◽

Optic Nerve ◽

General Anesthesia ◽

Optic Nerve Sheath Diameter ◽

Nerve Sheath ◽

End Tidal Carbon Dioxide ◽

Two Measures ◽

The Difference ◽

End Tidal ◽

Different Levels

Abstract Background Intracranial pressure (ICP) monitoring is an essential component in management of traumatic brain-injured (TBI) patients. While invasive techniques are associated with many complications, noninvasive nature of ultrasonographic measurement of optic nerve sheath diameter (ONSD) is now becoming popular. Carbon dioxide (CO2) alters the ICP by changing the size of cerebral vasculature. We aimed to assess the effect of (hypercarbia and hypocarbia) different levels of end-tidal carbon dioxide (EtCO2) on ONSD. Methods Thirty adult patients aged between 18 and 65 years, undergoing brachial plexus injury surgery under general anesthesia, were enrolled. Following standard anesthetic protocol, ONSD was measured at different time points of EtCO2. ONSD was measured at EtCO2 of 40 and then 30 mm Hg to assess change in ONSD due to hypocarbia (Thypocarbia). Similarly, ONSD was measured at EtCO2 of 50 mm Hg to assess change in ONSD due to hypercarbia (Thypercarbia). The mean of three ONSD values at each time point was taken as the final value. The generalized estimating equation (GEE) was used to analyze correlation between different levels of EtCO2 and ONSD. Results The calculated 95% confidence interval (CI) for the difference of two measures (Thypocarbia, EtCO2 40 and 30 mm Hg) on ONSD was −0.056 to −0.036, and the calculated CI for the difference of other two measures (Thypercarbia, EtCO2 40 and 50 mm Hg) on ONSD was 0.044 to 0.077, and thus were observed to be significant. Conclusions ONSD changes significantly in response to different EtCO2 levels in healthy non-neurosurgical patients under general anesthesia.

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