Monitoring Cerebral Blood Flow Pressure Autoregulation in Pediatric Patients During Cardiac Surgery

Abstract

Background and Purpose The limits of cerebral blood flow-pressure autoregulation have not been adequately defined for pediatric patients. Mean arterial blood pressure below these limits might contribute to brain injury during cardiac surgery. The purpose of this pilot study was to assess a novel method of determining the lower limits of pressure autoregulation in pediatric patients supported with cardiopulmonary bypass. Methods A prospective, observational pilot study was conducted in children (n=54) undergoing cardiac surgery with cardiopulmonary bypass for correction of congenital heart defects. Cerebral oximetry index (COx) was calculated as a moving, linear correlation coefficient between slow waves of arterial blood pressure and cerebral oximetry measured with near-infrared spectroscopy. An autoregulation curve was constructed for each patient with averaged COx values sorted by arterial blood pressure. Results Hypotension was associated with increased values of COx (P<0.0001). For 77% of patients, an individual estimate of lower limits of pressure autoregulation could be determined using a threshold COx value of 0.4. The mean lower limits of pressure autoregulation for the cohort using this method was 42±7 mm Hg. Conclusions This pilot study of COx monitoring in pediatric patients demonstrates an association between hypotension during cardiopulmonary bypass and impairment of autoregulation. The COx may be useful to identify arterial blood pressure-dependent limits of cerebral autoregulation during cardiopulmonary bypass. Larger trials with neurological outcomes are indicated.

The effects of CO2-insufflation with 5 and 10 mmHg during thoracoscopy on cerebral oxygenation and hemodynamics in piglets: an animal experimental study

“…However, we do think these results are representative as the trend of the cerebral oxygenation is more important than the absolute value [19]. There was no continuous registration of all parameters; thus, the relation between blood pressure and rScO 2 as an estimator of autoregulatory ability could not be measured [10,26]. In the future, a prospective, human study is required to confirm the effects of CO 2 -insufflation with 5 mmHg on cerebral oxygenation hemodynamics and with neurodevelopmental follow-up.…”

“…Because a significant decrease in the rScO 2 can be damaging, we gave preference to evaluate the effects of CO 2 -insufflation of up to 10 mmHg in this animal experimental model. Previous research showed that a nadir rScO 2 of less than 35 % [21] is associated with impairments in neurodevelopment [8,10].…”

“…The cause of this neurologic impairment in these patients is currently unknown and most likely multifactorial [8,9]. The neonatal brain is extremely vulnerable for external changes because of an immature autoregulatory system and hemodynamic instability, especially within the first days to weeks after birth in neonates [10].…”

Avoid hypotension and hypoxia: an old anesthetic adage with renewed relevance from cerebral oximetry monitoring

“…Cerebral oximetry, a noninvasive optical technology employing NIRS, may allow for real-time determination of the various autoregulatory thresholds 3 and thereby provide relevance as a means to define clinically meaningful hypotension. Cerebral oximetry measures regional cerebral blood (representing approximately 75% venous and 25% arterial content) oxygen saturation (rSO 2 ) using principles similar to conventional pulse oximetry (i.e., Beer-Lambert Law) which allow for the determination of oxygenated and deoxygenated hemoglobin by the differential absorption of various near-infrared light wavelengths.…”

“…L'oxymétrie cérébrale, une technologie optique non effractive utilisant la NIRS, pourrait permettre de déterminer en temps réel les divers seuils d'autorégulation, 3 ce qui pourrait avoir une pertinence dans la façon de définir une hypotension significative d'un point de vue clinique. À l'aide de principes semblables à ceux de l'oxymétrie de pouls conventionnelle (par ex.…”