Cerebral oxygen metabolism during total body flow and antegrade cerebral perfusion at deep and moderate hypothermia.
ABSTRACT The aim of this study is to evaluate the effect of temperature on cerebral oxygen metabolism at total body flow bypass and antegrade cerebral perfusion (ACP). Neonatal piglets were put on cardiopulmonary bypass (CPB) with the initial flow rate of 200mL/kg/min. After cooling to 18°C (n=6) or 25°C (n=7), flow was reduced to 100mL/kg/min (half-flow, HF) for 15min and ACP was initiated at 40mL/kg/min for 45min. Following rewarming, animals were weaned from bypass and survived for 4h. At baseline, HF, ACP, and 4 h post-CPB, cerebral blood flow (CBF) was measured using fluorescent microspheres. Cerebral oxygen extraction (CEO(2) ) and cerebral metabolic rate of oxygen (CMRO(2) ) were monitored. Regional cranial oxygen saturation (rSO(2) ) was continuously recorded throughout the procedure using near-infrared spectroscopy. At 18°C, CBF trended lower at HF and ACP and matched baseline after CPB. CEO(2) trended lower at HF and ACP, and trended higher after CPB compared with baseline. CMRO(2) at ACP matched that at HF. Cranial rSO(2) was significantly greater at HF and ACP (P<0.001, P<0.001) and matched baseline after CPB. At 25°C, CBF trended lower at HF, rebounded and trended higher at ACP, and matched baseline after CPB. CEO(2) was equal at HF and ACP and trended higher after CPB compared with baseline. CMRO(2) at ACP was greater than that at HF (P=0.001). Cranial rSO(2) was significantly greater at HF (P=0.01), equal at ACP, and lower after CPB (P=0.03). Lactate was significantly higher at all time points (P=0.036, P<0.001, and P<0.001). ACP provided sufficient oxygen to the brain at a total body flow rate of 100mL/kg/min at deep hypothermia. Although ACP provided minimum oxygenation to the brain which met the oxygen requirement, oxygen metabolism was altered during ACP at moderate hypothermia. ACP strategy at moderate hypothermia needs further investigation.
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ABSTRACT: Fractional anisotropy values in diffusion tensor imaging can quantitatively reflect the consistency of nerve fibers after brain damage, where higher values generally indicate less damage to nerve fibers. Therefore, we hypothesized that diffusion tensor imaging could be used to evaluate the effect of mild hypothermia on diffuse axonal injury. A total of 102 patients with diffuse axonal injury were randomly divided into two groups: normothermic and mild hypothermic treatment groups. Patient's modified Rankin scale scores 2 months after mild hypothermia were significantly lower than those for the normothermia group. The difference in average fractional anisotropy value for each region of interest before and after mild hypothermia was 1.32-1.36 times higher than the value in the normothermia group. Quantitative assessment of diffusion tensor imaging indicates that mild hypothermia therapy may be beneficial for patients with diffuse axonal injury.Neural Regeneration Research 01/2014; 9(2):190-197. · 0.23 Impact Factor
- Artificial Organs 11/2012; 36(11):943-50. · 1.87 Impact Factor
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ABSTRACT: OBJECTIVE: Selective antegrade cerebral perfusion (ACP) during hypothermic circulatory arrest (HCA) provides cerebral protection during aortic arch surgery. However, the ideal temperature for HCA during ACP remains unknown. Clinical outcomes were compared in patients who underwent moderate (nasopharyngeal temperature, ≥20°C) versus deep (nasopharyngeal temperature, <20°C) HCA with ACP during aortic arch repair. METHODS: By using a prospectively maintained clinical database, we analyzed data from 221 consecutive patients who underwent aortic arch replacement with HCA and ACP between December 2006 and May 2009. Seventy-eight patients underwent deep hypothermia (mean lowest temperature, 16.8°C ± 1.7°C) and 143 patients underwent moderate hypothermia (mean, 22.9°C ± 1.4°C) before systemic circulatory arrest was initiated. Multivariate stepwise logistic and linear regressions were performed to determine whether depth of hypothermia independently predicted postoperative outcomes and blood-product use. RESULTS: Compared with moderate hypothermia, deep hypothermia was associated independently with a greater risk of in-hospital death (7.7% vs 0.7%; odds ratio [OR], 9.3; 95% confidence interval [CI], 1.1-81.6; P = .005) and 30-day all-cause mortality (9.0% vs 2.1%; OR, 4.7; 95% CI, 1.2-18.6; P = .02), and with longer cardiopulmonary bypass time (154 ± 62 vs 140 ± 46 min; P = .008). Deep hypothermia also was associated with a higher incidence of stroke, although this association was not statistically significant (7.6% vs 2.8%; P = .073; OR, 4.3; 95% CI, 0.9-12.5). No difference was seen in acute kidney injury, blood product transfusion, or need for surgical re-exploration. CONCLUSIONS: Moderate hypothermia with ACP is associated with lower in-hospital and 30-day mortality, shorter cardiopulmonary bypass time, and fewer neurologic sequelae than deep hypothermia in patients who undergo aortic arch surgery with ACP.The Journal of thoracic and cardiovascular surgery 04/2013; · 3.41 Impact Factor