Cerebral blood flow pattern and autoregtilation during open-heart surgery in infants and young children

Buijs, Jeroen T.; F, van Bel; Nandorff, A.; Hardjowijono, R; Stijnen, Theo; Ottenkamp, Jaap

doi:10.1097/00003246-199206000-00013

Cited by 17 publications

(10 citation statements)

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“…In our study, how ever, venous Hb and mean arterial pressure were not different as compared to the cooling and rewarming phase. This may explain the difference between our study and the study of Fallon et al [14], Earlier reports investigating actual cerebral blood flow (133Xe clearance method) and cere bral blood flow (velocity) during hypothermic CPB in infants and young children, indeed found lower cerebral blood flows at lower body temperatures [2,4] and at steady-state hypothermic CPB. A good relationship be tween changes in CBV and actual cerebral blood flow determined with the l33Xe clear ance method was found in neonates with a stable great vessel Hb and hemodynamic con dition [26], Although in our patients individu al venous Hb values were mostly stable, indi vidual MAP values could fluctuate, which may alter the relationship between CBV and actual cerebral blood flow.…”

Section: Discussioncontrasting

confidence: 92%

“…in re lation with MAP (as a measure of effective cerebral perfusion pressure, see also Results), Tnas and the PR of the heart-lung machine. For this analysis a multiple linear regression model was used as described earlier [4], Briefly, ACBV or ACytaa? were the dependent variables, whereas MAP, Tnas and PR were taken as independent variables.…”

Section: Statistical a Nalysismentioning

confidence: 99%

“…In neonates and young children undergo ing cardiopulmonary bypass (CPB) during cardiovascular surgery, brain perfusion and metabolism, as well as electric activity of the brain are affected [1][2][3][4]. Although it is not clear yet whether or not CPB impairs future brain function and developmental outcome, recent experimental and clinical data strongly suggest that deep hypothermic CPB and espe cially circulatory arrest longer than 60 min may be detrimental [5][6][7], In previous studies, we and others showed that especially at deep hypothermic CPB, brain perfusion is very low and cerebral autoregulation seems to be easily disturbed [2,4], Moreover, Greely et al [8] found that the intracellular brain oxygenation of pediatric patients decreased significantly during circulatory arrest and remained im paired after rewarming and CPB despite nor malization of the oxygen availability.…”

Section: Introductionmentioning

confidence: 99%

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Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

et al. 1996

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Delay in development after open-heart surgery in infants has frequently been reported. Inadequate brain perfusion and oxygenation during deep hypothermic cardiopulmonary bypass (CPB) may play an important role. We investigated the effect of CPB on cerebral perfusion and oxygenation in 12 neonates and infants (age 0–11 months) undergoing open-heart surgery. Changes in cerebral blood volume (ΔCBV; in ml/100 g brain tissue) and oxidation level of the intracerebral mitochondrial enzyme cytochrome aa₃ (ΔCytaa₃; in µmol/l) were measured with near infrared spectroscopy. Nasopharyngeal temperature (T_nas) for assessment of changes in brain temperature, and mean arterial blood pressure (MAP) were monitored continuously. CBV lowered during cooling and increased during rewarming. These changes were only related with changes in Tnas (p < 0.001; 0.07 ml·100 g^-1/°C). No relation was found with changes in MAP or pump flow rate of the heart-lung machine. During steady-state hypothermic CPB, changes in CBV were only related to changes in MAP (p < 0.001). The individual regression lines between ΔCBV and MAP became steeper at lower absolute T_nas. Cytaa₃ showed an increase shortly after the initiation of CPB in 9 patients, with a sustained decrease to baseline values in 8 patients towards the end of the CPB period. Two patients who had a circulatory arrest during CPB had a sharp decrease in Δcytaa₃ after cessation of the heart-lung pump and showed no complete recovery of ΔCytaa₃ to baseline at the end of the CPB period. We conclude that changes in CBV during CPB are related to changes in T_nas. During deep hypothermic steady-state CPB, changes in CBV and MAP were related to each other, suggesting lack of cerebral autoregulation. The large decrease in Cytaa₃ in 2 patients with circulatory arrest suggests that this procedure compromises energy metabolism of the brain cell.

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Section: Discussioncontrasting

confidence: 92%

Section: Statistical a Nalysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

et al. 1996

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“…In newborn infants, circulatory arrest is accomplished at core temperatures ranging from 15°C to 24°C and even higher, depending on the experience and judgment of individual surgical teams. 16 - 38 The experimental findings presented here indicate that core temperatures as low as 16°C provide optimal protection at least to the newborn cerebral cortex without adversely influencing other organs, especially the heart. In addition, even small increments in core (and brain) temperature during hypothermic circulatory arrest increase the likelihood for brain injury to occur, especially when the arrest interval is extended beyond any previously defined safety margin.…”

Section: Discussionmentioning

confidence: 78%

Differences in intraischemic temperature influence neurological outcome after deep hypothermic circulatory arrest in newborn dogs.

Mujsce

Towfighi

Heitjan

et al. 1994

Stroke

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Background and Purpose Hypothermia to core temperatures ranging from 16°C to 24°C has become an established procedure to extend the "safe" interval of cardiac arrest during open heart surgery in human infants. The present experiment was designed to ascertain whether differences in core (rectal) temperature during hypothermic circulatory arrest influence the presence and extent of ischemic brain damage in newborn dogs.Methods Newborn dogs (postnatal age, 3 to 5 days) were anesthetized with halothane (4% induction; 0.5% maintenance), intubated, paralyzed, and artificially ventilated with 70% nitrous oxide/30% oxygen. Thereafter, the dogs were surface cooled with ice packs to either 16°C (n=6), 20°C (n=8), or 24°C (n=6). The dogs then were subjected to circulatory arrest for 1.75 hours by the intravenous injection of KC1, following which they were resuscitated with intravenous NaHCO 3 and epinephrine, artificial ventilation, and closed chest cardiac massage. Those dogs that survived for 8 hours of recovery (n=16) underwent neurobehavioral examination followed by perfusion-fixation of their brains for pathological analysis.Results All newborn dogs were successfully resuscitated after 1.75 hours of cardiac arrest, rewarmed to 37°C, and ultimately weaned from anesthesia and ventilatory support. Four dogs sustained secondary systemic complications with death at 4 to 7 hours. All surviving dogs remained stable, with systemic blood pressure, heart rate, arterial oxygen, and acid-base balance within the normal, normothermic range. Of

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“…Although cerebral autoregulation was present during normothermic bypass, it was absent during bypass both at 23-25 °C and 14-19 °C (Figure 3). In a similar study by Buijs et al, 64 also using transcranial Doppler techniques, cerebral autoregulation was present in children maintained on continuous cardiopulmonary bypass at approximately 25 °C, but was absent in those maintained at approximately 20 °C. Thus, there appears to be a transition point, at about approximately 23-25 °C, below which cerebral autoregulation is attenuated or abolished even with a-stat management Greeley et al 21 also noted the ratio of flow to metabolism during profound hypothermia to increase to values even greater than those observed during moderate hypothermia (see above).…”

Section: Cerebral Blood Flowmentioning

confidence: 63%

Cerebral physiology of hypothermia and hypothermic acid-base management during cardiopulmonary bypass

Hindman

1993

Cardiol Young

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Key words: Cardiopulmonary bypass; brain; hypothermia; cerebral blood flow; cerebral metabolism; brain protection C EREBRAL HYPOTHERMIA IS THE PRINCIPAL MEANS OF protecting the brain during cardiac surgery, permitting periods of reduced perfusion and/or circulatory arrest. For example, at 10-20 °C, circulatory arrest for 45-75 minutes is tolerated in animals without subsequent behavioral or histopathologic evidence of neurologic injury. 1 " 4 Nevertheless, clinically, die protective effect of hypothermia is far from complete. In children undergoing hypothermic circulatory arrest under equivalent conditions, coma, seizures, choreoathetosis, and developmental retardation are recognized as potential neurologic sequels, occurring widi a combined incidence of 10-30%. 59 Neurologic complications (stroke, neuropsychologic change) also occur with distressing frequency in adults undergoing cardiac surgery, even in the absence of circulatory arrest. 10 An improved understanding of the physiology of cerebral hypothermia during cardiopulmonary bypass and hypothermic arrest is needed to improve upon these results. This review will address current concepts and controversies regarding flow of blood to the brain and its metabolism during hypothermic cardiopulmonary bypass and their relationship to current techniques for cerebral protection. Mechanisms of hypothermic cerebral protectionThe time between the onset of cerebral ischemia and subsequent failure of neuronal energy 11 ' 12 and terminal depolarization of membranes 13 is related to cerebral metabolic rate. By reducing this rate, hypothermia slows the rate of depletion of high energy phosphate 111214 ' 15 and the development of intracellular acidosis during cerebral ischemia. 1415 In this way, hypothermia is thought to delay or prevent terminal depolarization of membranes during periods of cerebral ischemia (such as hypotension or circulatory arrest). The suppressive effect of hypothermia upon cerebral metabolism may be somewhat greater in children than in adults. Croughwell et al, 15 studying 41 adults during cardiopulmonary bypass at 27 °C, found the cerebral metabolic rate for oxygen to be reduced to a value ofapproximately36%ofthenormothermicvalue (1.4+0.3 vs 0.5±0.2 ml # 100 gnr^min' 1 ). In this, and comparable adult studies, the ratio of the metabolic rate over a 10 °C interval, referred to as Q^, ranged from 2.4 to 2.8. 17 " 20 Greeley et al, 21 studying cerebral blood flow and metabolism in 46 children during cardiopulmonary bypass, found the metabolic rate to decrease logarithmically with decreasing temperature to values of approximately 36% and 12% of normothermic values at 28 °C and 19 °C, respectively ( Figure 1). In this study, Q 10 ranged between 3.3 and 3.6, values somewhat greater than those found in adults. Assuming the tolerable cerebral ischemic interval at 37 °C to be 3-4 minutes, a cerebral temperature of 17 °C should permit 33-65 minutes of arrest ([3-5 min] x [3.3-3.6] x [3.3-3.6]) = 33-65 min). Greeley et al suggested that this predicted duration ...

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Cerebral blood flow pattern and autoregtilation during open-heart surgery in infants and young children

Cited by 17 publications

References 0 publications

Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

Differences in intraischemic temperature influence neurological outcome after deep hypothermic circulatory arrest in newborn dogs.

Cerebral physiology of hypothermia and hypothermic acid-base management during cardiopulmonary bypass

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