The Relationship among Canine Brain Temperature, Metabolism, and Function during Hypothermia

Michenfelder, John D.; Milde, James H.

doi:10.1097/00000542-199107000-00021

Cited by 255 publications

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Section: Methodsmentioning

confidence: 99%

“…The preparation of the animals for the study was iden tical to that previously described in detail (Michenfelder and Milde, 1991). In brief, CBF was measured by a sag ittal sinus outflow method (Michenfelder et aI., 1968;Takeshita et aI., 1972); brain temperature was monitored with a calibrated parietal epidural thermistor; and a four lead, two-channel EEG was recorded.…”

Section: Methodsmentioning

confidence: 99%

“…With rewarming to 37°C, cerebral metabolic variables returned to control It is commonly assumed that the basis for hypo thermia-induced cerebral protection is metabolic suppression. If one assumes that the temperature coefficient (QIO ) for CMR02 is similar to that for most biologic reaction rates of between 2.0 and 3.0 (Harper, 1973), the magnitude of protection clini cally observed at 15-18°C (Tharion et aI., 1982) ex ceeds that which would be predicted on a metabolic basis alone.In two previous studies we examined the effect of temperature on canine CMR02 over the tempera ture range of 14-37°C and demonstrated that the relationship is a complex one, resulting from the combined direct effect of temperature on biologic reaction rates and the effect this has on cerebral function as reflected by the EEG (Steen et aI., 1983;Michenfelder and Milde, 1991 877 levels. Brain biopsies taken at the end of the study yielded normal values for brain energy stores.…”

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confidence: 99%

“…Ventilation was controlled to maintain P ac02 at 35-40 mm Hg. Anesthesia was maintained with halothane 1% (end-expired) in nitrogen and oxygen which were ad justed to maintain Pa02 at 100--150 mm Hg.The preparation of the animals for the study was iden tical to that previously described in detail (Michenfelder and Milde, 1991). In brief, CBF was measured by a sag ittal sinus outflow method (Michenfelder et aI., 1968; …”

mentioning

confidence: 99%

“…In two previous studies we examined the effect of temperature on canine CMR02 over the tempera ture range of 14-37°C and demonstrated that the relationship is a complex one, resulting from the combined direct effect of temperature on biologic reaction rates and the effect this has on cerebral function as reflected by the EEG (Steen et aI., 1983;Michenfelder and Milde, 1991 877 levels. Brain biopsies taken at the end of the study yielded normal values for brain energy stores.…”

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confidence: 99%

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The Effect of Profound Levels of Hypothermia (Below 14°C) on Canine Cerebral Metabolism

Michenfelder

Milde

1992

J Cereb Blood Flow Metab

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Summary: The goal of this study was to determine the temperature coefficient (QIO) for canine CMR02 at tem peratures below 14°C. Eight dogs were anesthetized with halothane for surgical preparation. The animals were placed on total cardiopulmonary bypass and CBF was measured by direct sagittal sinus outflow. Duplicate mea surements were taken at 37, 13, and 7°C. The EEG be came isoelectric at a temperature of 12.0 ± 0.8°C. The QIO between 13 and 7°C was 2.19 ± 0.59. With rewarming to 37°C, cerebral metabolic variables returned to control It is commonly assumed that the basis for hypo thermia-induced cerebral protection is metabolic suppression. If one assumes that the temperature coefficient (QIO ) for CMR02 is similar to that for most biologic reaction rates of between 2.0 and 3.0 (Harper, 1973), the magnitude of protection clini cally observed at 15-18°C (Tharion et aI., 1982) ex ceeds that which would be predicted on a metabolic basis alone.In two previous studies we examined the effect of temperature on canine CMR02 over the tempera ture range of 14-37°C and demonstrated that the relationship is a complex one, resulting from the combined direct effect of temperature on biologic reaction rates and the effect this has on cerebral function as reflected by the EEG (Steen et aI., 1983;Michenfelder and Milde, 1991 877 levels. Brain biopsies taken at the end of the study yielded normal values for brain energy stores. We con clude that the QIO for CMR02 at temperatures between 7 and 37"C can be profoundly affected by the state of cere bral function as reflected by the EEG. In the absence of EEG activity, an expected QIO value of 2.2 reflects only the direct effect of temperature on the rates of biologic reactions. Key Words: Cerebral blood flow-Cerebral metabolic rate for oxygen-Cerebral protection Hypothermia.progresses from a near normal pattern to an isoelec tric one. Such a Q10 would fully explain the proven brain protection at 15-18°C.The present study was pursued to test the hy pothesis that the CMR02 effects of hypothermia re vert to a simple exponential relationship at and be low temperatures associated with an isoelectric EEG (below 14°C), resulting in a Q,o value of near 2.0. We are unaware of any other reports concerned with cerebral metabolic rates at temperatures below 14°C. METHODSThe protocol was reviewed and approved by the insti tutional animal care and use committee. Eight unmedi cated, fasting adult mongrel dogs, weighing 17.5 ± 2.2 kg (mean ± SD), were studied. Dogs were anesthetized with halothane 3-4% inspired followed by muscle paralysis with pancuronium 0.2 mg kg -I i. v. and intubation of the trachea. Ventilation was controlled to maintain P ac02 at 35-40 mm Hg. Anesthesia was maintained with halothane 1% (end-expired) in nitrogen and oxygen which were ad justed to maintain Pa02 at 100--150 mm Hg.The preparation of the animals for the study was iden tical to that previously described in detail (Michenfelder and Milde, 1991). In brief, CBF was measured by a sag ittal sinus outflow method (Mic...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The Effect of Profound Levels of Hypothermia (Below 14°C) on Canine Cerebral Metabolism

Michenfelder

Milde

1992

J Cereb Blood Flow Metab

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The bypass plan

Matte

2015

Perfusion for Congenital Heart Surgery

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The perfusionist must be familiar with the patient's original diagnosis, catheterization lab interventions, previous surgeries, and current needs when developing the bypass plan. The following are major considerations for management of the patient during cardiopulmonary bypass. Please refer to Chapter 6 for defect-specific considerations.The care team must have a reasonably standardized communication plan for the bypass run [1][2][3]. This includes standardizing to closed-loop communication for certain anesthesia, surgical, and cardiopulmonary bypass (CPB) commands, notifications, and/or concerns. Each communication should be verbally acknowledged per the team standard (either repeated back or with another affirmation) to ensure the information is properly delivered and handled. This technique is essential for bypass safety and is used at most centers to announce checkpoints during the case.Common bypass-related checkpoints where closedloop communication among the team is essential include the following: • Heparin in • ACT running • Bypass lines clamped and ready for division at the field • Pump suckers on (with suckers and vent line tested under saline at field)

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Perioperative Thermoregulation and Heat Balance

Grimm

2015

Veterinary Anesthesia and Analgesia

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The Relationship among Canine Brain Temperature, Metabolism, and Function during Hypothermia

Cited by 255 publications

References 0 publications

The Effect of Profound Levels of Hypothermia (Below 14°C) on Canine Cerebral Metabolism

The Effect of Profound Levels of Hypothermia (Below 14°C) on Canine Cerebral Metabolism

The bypass plan

Perioperative Thermoregulation and Heat Balance

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