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Cerebrovascular reactivity monitoring has been used to identify the lower limit of pressure autoregulation in adult patients with brain injury. We hypothesise that impaired cerebrovascular reactivity and time spent below the lower limit of autoregulation during cardiopulmonary bypass will result in hypoperfusion injuries to the brain detectable by elevation in serum glial fibrillary acidic protein level.
We designed a multicentre observational pilot study combining concurrent cerebrovascular reactivity and biomarker monitoring during cardiopulmonary bypass. All children undergoing bypass for CHD were eligible. Autoregulation was monitored with the haemoglobin volume index, a moving correlation coefficient between the mean arterial blood pressure and the near-infrared spectroscopy-based trend of cerebral blood volume. Both haemoglobin volume index and glial fibrillary acidic protein data were analysed by phases of bypass. Each patient’s autoregulation curve was analysed to identify the lower limit of autoregulation and optimal arterial blood pressure.
A total of 57 children had autoregulation and biomarker data for all phases of bypass. The mean baseline haemoglobin volume index was 0.084. Haemoglobin volume index increased with lowering of pressure with 82% demonstrating a lower limit of autoregulation (41±9 mmHg), whereas 100% demonstrated optimal blood pressure (48±11 mmHg). There was a significant association between an individual’s peak autoregulation and biomarker values (p=0.01).
Individual, dynamic non-invasive cerebrovascular reactivity monitoring demonstrated transient periods of impairment related to possible silent brain injury. The association between an impaired autoregulation burden and elevation in the serum brain biomarker may identify brain perfusion risk that could result in injury.
Background: Although some prior studies have provided evidence to question the historical belief that pulmonary vascular resistance index ⩾6 Wood Units×m2 should be a contraindication to heart transplantation in children, no national analyses specific to the modern area have addressed this question. Methods: Data were analysed for paediatric heart transplant recipients from 1 January, 2002 to 1 September, 2012 (n=699). The relationship between pulmonary vascular resistance and all-cause 30-day mortality was evaluated using univariate and multivariate analyses. Results: The 30-day mortality included 10 patients (1.43%), which is lower than in the previous analyses. Receiver operating curve analysis of pulmonary vascular resistance index as a predictor of mortality yielded a cut-off value of 3.37 Wood Units×m2, but the area under the curve and specificity of this threshold was weaker than in previous analyses. Whereas pulmonary vascular resistance index treated as a dichotomised variable was a significant predictor of mortality in univariate (odds ratio 4.92, 95% confidence interval 1.04–23.33, p=0.045) and multivariate (odds ratio 5.26, 95% confidence interval 1.07–25.80, p=0.041) analyses, pulmonary vascular resistance index treated as a continuous variable was not a significant predictor of mortality in univariate (p=0.12) or multivariate (p=0.11) analyses. Conclusions: The relationship between pulmonary vascular resistance and post-heart transplant mortality in children is less convincing in this analysis of a comprehensive, contemporary database than in previous series. This suggests the possibility that modern improvements in the management of post-transplant right ventricular dysfunction have mitigated the contribution of pulmonary hypertension to early mortality.
Objective: To determine whether blood levels of the brain-specific biomarker glial fibrillary acidic protein rise during cardiopulmonary bypass for repair of congenital heart disease. Methods: This is a prospective observational pilot study to characterise the blood levels of glial fibrillary acidic protein during bypass. Children <21 years of age undergoing bypass for congenital heart disease at Johns Hopkins Hospital and Texas Children's Hospital were enrolled. Blood samples were collected during four phases: pre-bypass, cooling, re-warming, and post-bypass. Results: A total of 85 patients were enrolled between October, 2010 and May, 2011. The median age was 0.73 years (range 0.01–17). The median weight was 7.14 kilograms (range 2.2–86.5). Single ventricle anatomy was present in 18 patients (22%). Median glial fibrillary acidic protein values by phase were: pre-bypass: 0 ng/ml (range 0–0.35); cooling: 0.039 (0–0.68); re-warming: 0.165 (0–2.29); and post-bypass: 0.112 (0–0.97). There were significant elevations from pre-bypass to all subsequent stages, with the greatest increase during re-warming (p = 0.0001). Maximal levels were significantly related to younger age (p = 0.03), bypass time (p = 0.03), cross-clamp time (p = 0.047), and temperature nadir (0.04). Peak levels did not vary significantly in those with single ventricle anatomy versus two ventricle repairs. Conclusion: There are significant increases in glial fibrillary acidic protein levels in children undergoing cardiopulmonary bypass for repair of congenital heart disease. The highest values were seen during the re-warming phase. Elevations are significantly associated with younger age, bypass and cross-clamp times, and temperature nadir. Owing to the fact that glial fibrillary acidic protein is the most brain-specific biomarker identified to date, it may act as a rapid diagnostic marker of brain injury during cardiac surgery.
The modern practice of sedation is the end result of a process of evolution in alteration of consciousness, likely starting with the discovery of the analgesic properties of ether. Recent technological advances have drastically changed the practice of sedation. One of the most significant was certainly the development of pulse oximetry during World War II by Glen Millikan. In 2002, the American Society of Anesthesiologists (ASA) appointed a task force to update practice guidelines for non-anesthesiologists administering sedation and analgesia. The Association of periOperative Registered Nurses (AORN) has produced guidelines for what every registered nurse should know about "conscious sedation". According to the AORN, moderate sedation/analgesia is produced by the administration of amnesic, analgesic, and sedative pharmacologic agents. With continued attention to a high standard of safety, many different professionals are able to provide sedation services to those patients who need them.
This chapter deals with important considerations with regard to pre-procedure, peri-procedure, and post-procedure patient assessment and pain management strategies. Practitioner training and experience in administering sedation is an important consideration. For most patients, pain assessments and establishment of pain treatment goals can be performed by a non-anesthesiologist. Appropriate assessment of pain increases caregiver awareness of pain status, allows for the delivery of appropriate interventions, provides for feedback, decreases both patient and caregiver frustration, and improves patient satisfaction. The chapter outlines the most common pain assessment tools in current use in general and special populations. In the general population, which includes mature children, adults, and the cognitively intact elderly, the use of self-report scales has been validated as the most reliable indicator of pain. With appropriate vigilance, planning, and continuous communication between team members, many of the barriers involved in planning and executing an effective pain management strategy can be overcome.