Time course of changes in cerebral blood flow velocity after tourniquet deflation in patients with diabetes mellitus or previous stroke under sevoflurane anesthesia.

Division of Intensive Care, Gunma University Hospital, Maebashi, Japan.
Journal of Anesthesia (Impact Factor: 0.87). 04/2011; 25(3):409-14. DOI: 10.1007/s00540-011-1131-6
Source: PubMed

ABSTRACT We observed an increase in mean middle cerebral artery blood flow velocity (V(mca)) after tourniquet deflation during orthopedic surgery under sevoflurane anesthesia in patients with diabetes mellitus or previous stroke. Eight controls, seven insulin-treated diabetic patients, and eight previous stroke patients were studied. Arterial blood pressure, heart rate, V(mca), arterial blood gases, and plasma lactate levels were measured every minute for 10 min after tourniquet release in all patients. V(mca) was measured using a transcranial Doppler probe. V(mca) in all three groups increased after tourniquet deflation, the increase lasting for 4 or 5 min. However, the degree of increase in V(mca) in the diabetic patients was smaller than that in the other two groups after tourniquet deflation (at 2 min after tourniquet deflation: control 58.5 ± 3.3, previous stroke 58.4 ± 4.6, diabetes 51.7 ± 2.3; P < 0.05 compared with the other two groups). In conclusion, the degree of increase in V (mca) in diabetic patients is smaller than that in controls and patients with previous stroke.

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    ABSTRACT: We studied the changes in end-tidal CO(2) (ET(CO)(2)) and systemic responses after tourniquet deflation in spontaneously breathing and ventilation-controlled patients during orthopedic surgery of both the upper and/or the lower extremities. In most patients, increases in ET(CO)(2), heart rate, and Pa(CO)(2), as well as decreases in blood pressure and pH were observed. In every spontaneously breathing patient, the respiratory rate began to increase before the ET(CO)(2) reached a maximum. Arterial blood gas analysis suggested that the increase in ET(CO)(2) closely reflected the increase in Pa(CO)(2). Our study yielded new information on the ET(CO)(2) changes as follows: 1) the time for ET(CO)(2) level to reach a peak (peak time) was almost constant despite the considerable differences in the increases in ET(CO)(2) both in spontaneous breathing and ventilation-controlled groups and the peak time in the former group was shorter than that in the latter group; and 2) it was suggested that the increase in ET(CO)(2) in the spontaneously breathing patients was smaller than that in ventilation-controlled patients when both patients were subjected to the same conditions on tourniquet time and tourniqueted area. Our data showed that the increase in ET(CO)(2) (or Pa(CO)(2)) can be large and prolonged in some situations. Thus, we recommend continuous ET(CO)(2) monitoring and the proper hyperventilation at tourniquet deflation in order to minimize any adverse effects of acidosis.
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