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Rapid brain cooling in intubated pigs through nasal flushing with oxygen: prevention of brain hyperthermia.

Einer-Jensen N, Khorooshi MH, Petersen MB, Svendsen P - Acta Vet. Scand. (2001)

Bottom Line: Local cooling of the brain by the respiratory air is found in many animal species.The nasal oxygen flow constantly induced a rapid, reversible and flow dependant decrease in brain temperature: 0.25 degree C +/- 0.04, (n = 2) (mean +/- SD, n) at < 4 l/min; 1.35 degrees C +/- 0.78, (n = 20) at 4-6 l/min; and 1.44 degrees C +/- 0.62, (n = 6) at > 6 l/min.The ventricle temperature decreased 0.59 degree C +/- 0.23, (n = 8) when the animals were transferred to spontaneous respiration and the tracheal tube removed.

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Affiliation: Dept. Physiology & Pharmacology, University of Southern Denmark. n.einer-jensen@imbmed.sdu.dk

ABSTRACT
Local cooling of the brain by the respiratory air is found in many animal species. The mechanism is based on cooling of the nasal vein blood and heat transfer in the cavernous sinus/carotid artery complex and is therefore not active in anaesthetised, intubated animals. The present experiment was made to investigate the effects of oxygen flushing of the nasal cavities in such animals. Nine anaesthetised, intubated male pigs were used. The temperatures in the third ventricle and rectum were measured continuously. Oxygen was infused into the nasal cavities during 10 min periods interrupted by 10 min without flow. The nasal oxygen flow constantly induced a rapid, reversible and flow dependant decrease in brain temperature: 0.25 degree C +/- 0.04, (n = 2) (mean +/- SD, n) at < 4 l/min; 1.35 degrees C +/- 0.78, (n = 20) at 4-6 l/min; and 1.44 degrees C +/- 0.62, (n = 6) at > 6 l/min. The ventricle temperature decreased 0.59 degree C +/- 0.23, (n = 8) when the animals were transferred to spontaneous respiration and the tracheal tube removed. It may be possible to protect the brain in intubated animals and humans from heat-induced damages by establishment of nasal flushing.

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Brain, rectal and ear temperatures in an anaesthetised, intubated pig. The nasal cavities were flushed with oxygen (2–10 l/min) in repeated 10-min periods. The brain temperature was measured in the third ventricle; the position of the probe was controlled by a x-ray. The tracheal tube was removed at the end of the experiment.
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Figure 1: Brain, rectal and ear temperatures in an anaesthetised, intubated pig. The nasal cavities were flushed with oxygen (2–10 l/min) in repeated 10-min periods. The brain temperature was measured in the third ventricle; the position of the probe was controlled by a x-ray. The tracheal tube was removed at the end of the experiment.

Mentions: Brain temperature was similar to the rectal temperature during the last minute of the control periods (no oxygen flushing). Flushing the nasal cavities with oxygen constantly induced a decrease in brain temperature in all 9 intubated animals. The decrease was observed within minutes, reached a steady state after 5–8 min and reversed within minutes after ceasing the gas flow (Fig. 1). The decrease was flow dependant: 0.25°C ± 0.04, (n = 2) (mean ± sd, (n)) at <4 l/min; 1.35°C ± 0.78, (20) at 4–6 l/min; and 1.44°C ± 0.62, (6) at >6 l/min (Fig. 2 and 3). Cooling or humidifying the gas had no obvious effect (Fig 4). Cooling was observed throughout the 2 one-hour oxygen flushing sessions. Only when using high oxygen flow rates did we observe a small decrease in the tympanic and rectal temperatures.


Rapid brain cooling in intubated pigs through nasal flushing with oxygen: prevention of brain hyperthermia.

Einer-Jensen N, Khorooshi MH, Petersen MB, Svendsen P - Acta Vet. Scand. (2001)

Brain, rectal and ear temperatures in an anaesthetised, intubated pig. The nasal cavities were flushed with oxygen (2–10 l/min) in repeated 10-min periods. The brain temperature was measured in the third ventricle; the position of the probe was controlled by a x-ray. The tracheal tube was removed at the end of the experiment.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2203225&req=5

Figure 1: Brain, rectal and ear temperatures in an anaesthetised, intubated pig. The nasal cavities were flushed with oxygen (2–10 l/min) in repeated 10-min periods. The brain temperature was measured in the third ventricle; the position of the probe was controlled by a x-ray. The tracheal tube was removed at the end of the experiment.
Mentions: Brain temperature was similar to the rectal temperature during the last minute of the control periods (no oxygen flushing). Flushing the nasal cavities with oxygen constantly induced a decrease in brain temperature in all 9 intubated animals. The decrease was observed within minutes, reached a steady state after 5–8 min and reversed within minutes after ceasing the gas flow (Fig. 1). The decrease was flow dependant: 0.25°C ± 0.04, (n = 2) (mean ± sd, (n)) at <4 l/min; 1.35°C ± 0.78, (20) at 4–6 l/min; and 1.44°C ± 0.62, (6) at >6 l/min (Fig. 2 and 3). Cooling or humidifying the gas had no obvious effect (Fig 4). Cooling was observed throughout the 2 one-hour oxygen flushing sessions. Only when using high oxygen flow rates did we observe a small decrease in the tympanic and rectal temperatures.

Bottom Line: Local cooling of the brain by the respiratory air is found in many animal species.The nasal oxygen flow constantly induced a rapid, reversible and flow dependant decrease in brain temperature: 0.25 degree C +/- 0.04, (n = 2) (mean +/- SD, n) at < 4 l/min; 1.35 degrees C +/- 0.78, (n = 20) at 4-6 l/min; and 1.44 degrees C +/- 0.62, (n = 6) at > 6 l/min.The ventricle temperature decreased 0.59 degree C +/- 0.23, (n = 8) when the animals were transferred to spontaneous respiration and the tracheal tube removed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept. Physiology & Pharmacology, University of Southern Denmark. n.einer-jensen@imbmed.sdu.dk

ABSTRACT
Local cooling of the brain by the respiratory air is found in many animal species. The mechanism is based on cooling of the nasal vein blood and heat transfer in the cavernous sinus/carotid artery complex and is therefore not active in anaesthetised, intubated animals. The present experiment was made to investigate the effects of oxygen flushing of the nasal cavities in such animals. Nine anaesthetised, intubated male pigs were used. The temperatures in the third ventricle and rectum were measured continuously. Oxygen was infused into the nasal cavities during 10 min periods interrupted by 10 min without flow. The nasal oxygen flow constantly induced a rapid, reversible and flow dependant decrease in brain temperature: 0.25 degree C +/- 0.04, (n = 2) (mean +/- SD, n) at < 4 l/min; 1.35 degrees C +/- 0.78, (n = 20) at 4-6 l/min; and 1.44 degrees C +/- 0.62, (n = 6) at > 6 l/min. The ventricle temperature decreased 0.59 degree C +/- 0.23, (n = 8) when the animals were transferred to spontaneous respiration and the tracheal tube removed. It may be possible to protect the brain in intubated animals and humans from heat-induced damages by establishment of nasal flushing.

Show MeSH
Related in: MedlinePlus