Anesthetics Affect the Cerebral Metabolic Response to Circulatory Catecholamines

Artru, Alan A.; Nugent, Michael; Michenfelder, John D.

doi:10.1111/j.1471-4159.1981.tb10818.x

Cited by 20 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In groups I and II control CBF values were higher than values observed during surgical levels of anesthesia (CBF = 60-70 ml-100 g-'-min-'), 17 -19 but less than or equal to values during light anesthesia with N 2 O (60-70%) and halothane ( < 0.1%) in O, (CBF « 80-140 mMOO g-'-min-1 ) 18 -2 ' with this model. In previous studies high control CBF values during light anesthesia have not impaired subsequent determination of CBF, cerebral metabolic rate for oxygen, cerebral metabolites (ATP, lactate, pyruvate, phosphocreatine, etc.…”

Section: Discussionmentioning

confidence: 61%

Cerebral blood flow responses to hypocapnia during hypotension.

Artru

Colley

1984

Stroke

View full text Add to dashboard Cite

SUMMARY Cerebral vascular responses to hypocapnia during hypotension to a mean arterial blood pressure (MAP) = 50 mm Hg induced with sodium nitroprusside (SNP, n = 12) or trimethaphan (TMP, n = 12) were examined in dogs. Cerebral vascular resistance (CVR) and cerebral blood flow (CBF) at P a= 40 mm Hg, and Pa C0; = 20 mm Hg were examined first at normal MAP then at hypotension in six dogs in the SNP group and six dogs in the TMP group. In both the SNP group and the TMP group, CO 2 responsiveness, as indicated by increased CVR and decreased CBF, was intact at normal MAP, but absent during hypotension. In the remaining 6 of 12 dogs in the SNP group and 6 of 12 dogs in the TMP group, CO 2 responsiveness at MAP = 50 mm Hg was examined without prior determination of CO 2 responsiveness at normal MAP. These additional studies were performed to rule out the possibility that absent CO 2 responsiveness during hypotension in the initial groups resulted from (1) physiologic deterioration of the preparation with time, or (2) adaptation of brain extracellular fluid pH to a proceeding period of hypocapnia. Again, during both SNP-or TMP-induced hypotension CO 2 responsiveness was absent. Stroke Vol 15, No 5, 1984 PREVIOUS STUDIES have reported that hypocapnia causes increased cerebral vascular resistance (CVR) and decreased cerebral blood flow (CBF) at mean arterial pressures (MAP) > 60 mm Hg but not at MAP < 50 when hypotension is induced with hemorrhage or halothane.1 " 4 In clinical practice, elective, controlled hypotension is more commonly achieved with sodium nitroprusside (SNP) or trimethaphan (TMP) rather than hemorrhage or halothane. Based on currently available data, it is not certain whether cerebral vascular responses to hypocapnia also are absent at MAP ^ 50 mm Hg when SNP or TMP are used to produce hypotension. Gregory et al examined the CO, responsiveness of CBF during SNP-induced hypotension (MAP = 37 mm Hg) in cats and reported that when arterial P C02 was altered between 17 and 51 mm Hg, some CO 2 responsiveness persisted though at less than half control levels. 5 However, in that study hypotension was not produced by SNP alone but by combining SNP with practolol, hemorrhage, and 0.5-0.7% halothane. Sullivan et al observed changes in the electroencephalogram (EEG) with hypocapnia (Pa,^ = 18 mm Hg) during SNP-induced hypotension (MAP = 50 mm Hg) in man and speculated that hypocapnia caused cerebral vasoconstriction. 6 However, CVR or CBF were not measured and the EEG changes may have been the result of combining hypocapnia with enfiurane anesthesia.7 -8 Regarding TMP, Hamer et al reported that 5% CO 2 increased CBF in dogs during TMP-induced hypotension to MAP = 40 mm Hg. 9Speculation about cerebral vascular reactivity to hypocapnia during TMP-induced hypotension could only be by extrapolation because CBF responses to hypocapnia were not examined. In contrast, Gregory et al. reported absent CBF responses when P a^ was altered between 20 and 50 mm Hg during TMP-induced hypotension to MAP = 36 mm Hg in cats. ...

show abstract

Section: Discussionmentioning

confidence: 61%

Cerebral blood flow responses to hypocapnia during hypotension.

Artru

Colley

1984

Stroke

View full text Add to dashboard Cite

show abstract

“…Within the 62 animal studies identified, the majority of cases measured CBF response to NE and other agents, utilizing: autoradiographic diffusible tracer technique, electromagnetic flow probe, freely diffusible tracers, thermal diffusion probe, clearance method, laser‐Doppler flow velocity, radioactive gas elimination, radioactive microsphere, flow transducer and flow meter, visual recording software, and two other methods. The animal models studied included baboons (3), 17‐19 cats (8), 20‐27 dogs (11), 28‐38 goats (3), 39‐41 pigs (12), 42‐53 sheep (1), 54 mice (1), 55 rabbits (5), 56‐60 rats (17) 61‐77 and one retrospective study 16 with dogs, cats, rats, and humans. The characteristics of the animal studies can be seen in Tables 1 and 2.…”

Section: Resultsmentioning

confidence: 99%

“…The majority of the models was heavily anesthetized, with only two studies where the animals were lightly sedated 40,42 and four studies where animals had no sedation or anesthetia 39,41,55,60 . A further four articles 27,38,44,70 had NE injected with another vasoactive substance, seven articles 20,23,27,52‐54,70 where the models had craniotomy, five articles 34,36,37,73,77 where models had explanted brains for the evaluation of vessel response, four articles 44‐47 where models were administered cardiopulmonary resuscitation (CPR) during NE injection, four articles 48,50,51,74 where models had a TBI, three articles 21,35,66 where some models had hypothermia, two articles 41,56 where models had a superior cervical sympathetic ganglionectomy, one article where models had bile duct ligations, 19 and one article where models had induced endotoxin shock 43 . Seventeen studies had NE administered at varying dose levels on healthy models 17,20,26,29,36,39,40,52‐54,59,63‐65,69,71,72 .…”

Section: Resultsmentioning

confidence: 99%

“…Seventeen studies had NE administered at varying dose levels on healthy models 17,20,26,29,36,39,40,52‐54,59,63‐65,69,71,72 . In 23 of the studies the partial pressure of oxygen and carbon dioxide were either controlled through ventilation, 21,25,29,31,35,43‐49,51,53,56,57,60‐62,66,70,71,73 or taken to be constant throughout the study in 28 17‐19,22‐24,28,30,32‐34,36‐39,50,52,54,55,58,59,63‐65,68,72,74,75 . Ten studies did not mention accounting for the pCO 2 or pO 2 20,26,27,40‐42,67,69,76,77 …”

Section: Resultsmentioning

confidence: 99%

“…Twenty‐six studies demonstrated an increase in global or rCBF with the administration of NE 17,18,23,25,36,38,40,41,45‐50,62‐65,67‐72,75,76 . The CBF increase ranged from not significant, to changes on the order of 500% of the initial CBF value 45 .…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations