Effect of dextran on cerebral function and blood after cardiac arrest. An experimental study on the dog.

Abstract

SUMMARY EEG activity and regional cerebral blood flow were monitored during S hour survival following cardiac arrest in 32 pentobarbital anesthetized mongrel dogs. The animals were mechanically ventilated and blood gases were maintained at physiologic levels. Regional cerebral blood flow and cardiac output were measured using 15 n microspheres. EEG was recorded from 6 epidural electrodes using bipolar techniques.The animals were divided into 3 groups. The animals in Group I had an arrest of 8-11 minutes and those in Group II and III had an arrest of 12-16 minutes. Group II animals received no treatment. Group III animals were given 1 g/kg of dextran 40 at a concentration of 10% in normal saline following the arrest and maintained with 10 mg/kg/min during the 5 hours of recovery. In Groups I and III there was shorter duration of a flat EEG and 5 hours after the arrest the EEG activity was closer to normal than in Group II. After 5 hours the EEG scores of Group III were significantly greater than Group II (p < 0.03). The cortical grey matter and hippocampus had the greatest reduction of blood flow following cardiac arrest. The mean cortical grey matter blood flow in Group II was less than in Groups I and III at 3 hours. After 5 hours the grey matter blood flow was greater in Group III than in Group II (p < 0.09).The findings of this study are consistent with the hypothesis that after cardiac arrest perfusion abnormalities persist or develop after return of blood pressure and that these can be corrected or prevented with improved functional survival by treatment with dextran 40 after the arrest.Stroke, Vol 10, Nol, 1979 LOW MOLECULAR WEIGHT dextran 40 (Rheomacrodex) has been shown to diminish mortality and to enhance the quality of survival when given to patients following acute stroke." Experimental study also has shown that administration of this hemodiluting agent following cerebral arterial occlusion reduced the circulatory impairment at the microvasculature level. 36 Dextran's effectiveness may be related to its action in reducing blood viscosity and increasing plasma volume; 12 ' 37 to its effect in minimizing aggregation of formed blood elements; 13 or to an antiplatelet aggregation effect. 13 These actions suggest that low molecular weight dextran may be of value in the treatment of the brain injury induced by circulatory arrest, particularly if "no reflow" 1 is an important cause of such injury. MethodsThirty-two nonheparinized mongrel dogs, revived from cardiac arrest and maintained 5 hours during the postarrest period, were analyzed. They were divided into 3 groups. Animals in Group I (n = 8) had an arrest of 8-11 minutes and those in Group II (n = 12) had an arrest of 12-16 minutes. Animals in Group III (n = 12) had an arrest of 12-16 minutes followed by treatment with a high dose of 40,000 molecular weight

Regional cerebral glucose metabolism during and after bilateral cerebral ischemia in the gerbil.

“…But it seems that the postischemic brain gets better reperfusion with the infusion of dextran than without since arterial blood pressure was stabilized with the addition of this fluid and it does not cause any decrement in blood flow. 26 Thus observed changes in CMRG are if anything an underestimation of true metabolic alterations during the reperfusion period.…”

Why do all drugs work in animals but none in stroke patients ? 1 Drugs promoting cerebral blood flow

“…Dextran, a collection of polydisperse polysaccharides, reduces whole-blood viscosity in vitro, and has antiplatelet properties which derive from coating of platelets 1471. In dogs, isovolaemic haemodilution with dextran increased cardiac output and intracranial pressure [48], whilst dextran infusion following cardiac arrest was associated with augmentation of grey matter CBF and a somewhat improved EEG score [49]. In 10 primates undergoing transorbital MCA clipping, Hartmann et al described a significant increase in rCBF in the MCA territory following hypervolaemic haemodilution with lowmolecular-weight (LMW) dextran which was ac-companied by a moderate haematocrit reduction Hetastarch, a polydisperse hydroxyethylated preparation of amylopectin with a mean molecular weight of 480 kDa, has also been employed for volume expansion.…”