Noninvasive Neuromonitoring of Hypothermic Circulatory Arrest in Aortic Surgery.

BACKGROUND AND AIMS: Circulatory arrest carries a high risk of neurological damage, but modern monitoring methods lack reliability, and is susceptible to the generalized effects of both anesthesia and hypothermia. The objective of this prospective, explorative study was to research promising, reliable, and noninvasive methods of neuromonitoring, capable of predicting neurological outcome after hypothermic circulatory arrest. MATERIALS AND METHODS: Thirty patients undergoing hypothermic circulatory arrest during surgery of the thoracic aorta were recruited in a single center and over the course of 4 years. Neuromonitoring was performed with a four-channel electroencephalogram montage and a near-infrared spectroscopy monitor. All data were tested off-line against primary neurological outcome, which was poor if the patient suffered a significant neurological complication (stroke, operative death). RESULTS: A poor primary neurological outcome seen in 10 (33%) patients. A majority (63%) of the cases were emergency surgery, and thus, no neurological baseline evaluation was possible. The frontal hemispheric asymmetry of electroencephalogram, as measured by the brain symmetry index, predicted primary neurological outcome with a sensitivity of 79 (interquartile range; 62%-88%) and specificity of 71 (interquartile range; 61%-84%) during the first 6 h after end of circulatory arrest. CONCLUSION: The hemispheric asymmetry of frontal electroencephalogram is inherently resistant to generalized dampening effects and is predictive of primary neurological outcome. The brain symmetry index provides an easy-to-use, noninvasive neuromonitoring method for surgery of the thoracic aorta and postoperative intensive care.

Long-Term Survival and Quality of Life After Hypothermic Circulatory Arrest in Aortic Surgery.

BACKGROUND AND AIMS:: Hypothermic circulatory arrest carries a high risk of mortality and neurological complications. An important part of assessing surgical treatment is the evaluation of long-term survival and postoperative health-related quality of life. MATERIAL AND METHODS:: In this prospective study, 30 patients undergoing hypothermic circulatory arrest during surgery of the thoracic aorta, and 31 comparison patients undergoing elective coronary artery surgery without hypothermic circulatory arrest were evaluated for long-term survival and health-related quality of life, using the RAND 36-Item Health Survey questionnaire. The results were compared to national age- and sex-matched reference populations of the chronically ill and healthy adults. RESULTS:: After 4.6-8.0 years, available study (88%) and comparison (59%) patients were interviewed. The life expectancy was similar with 4- and 8-year survival of 90%, and 87% for the study group, and 94%, and 94% for the comparison group, respectively (log rank test, p = 0.62). The RAND-36 scores for study and comparison groups were congruent in all dimensions, describing physical, mental, and social domains. The study patients' health-related quality of life results were similar to the national reference population with chronic illnesses. CONCLUSION:: After hypothermic circulatory arrest, patients undergoing surgery of the thoracic aorta achieve a similar long-term life expectancy and health-related quality of life as do patients undergoing coronary surgery without hypothermic circulatory arrest, and a health-related quality of life similar to the national reference population with chronic illnesses. These results justify operative treatment in this high-risk patient population.

Transient hyperdynamic response associated with controlled hypocapneic hyperventilation during sevoflurane-nitrous oxide mask induction in adults.

UNLABELLED: We assessed hemodynamic variables during sevoflurane face mask anesthetic induction in female ASA physical status I or II patients. Anesthesia was induced with a single-breath inhalation method with 8% sevoflurane in 50% nitrous oxide in oxygen. Thirty patients were randomized either to breathe spontaneously (SB group, n = 15) or to receive controlled ventilation (CV group, n = 15) for 6 min after the loss of consciousness. Noninvasive blood pressure and heart rate (HR) were recorded at 1-min intervals. Mean +/- SD HR increased from 83+/-18 to 112+/-24 bpm at 4 min in the CV group (P < 0.001 between groups and within group compared with baseline). Mean arterial pressure increased from 97+/-9 to 106+/-26 mm Hg at 4 min in the CV group, which was significantly higher than that in the SB group (P < 0.01). In the SB group, mean arterial pressure decreased significantly, from 96+/-8 to 78+/-13 mmHg, at 6 min (P < 0.001), and HR remained unchanged. Therefore, hyperventilation should be avoided during the induction of sevoflurane anesthesia via a mask. IMPLICATIONS: In this randomized, prospective study, we found that controlled hypocapneic hyperventilation delivered manually during sevoflurane/ N2O/O2 mask induction was associated with a significant transient hyperdynamic response. This kind of hemodynamic arousal can be detrimental to many patients and can be avoided by conducting sevoflurane mask induction with unassisted spontaneous breathing.