![]() ![]() The different techniques used to monitor cerebral blood flow may contribute to differences in results. ![]() In many cases, adrenaline reduces microcirculatory flow, even if global organ blood flow is either increased or unchanged. In summary, adrenaline increases the mean aortic pressure, but the effect on coronary and cerebral blood flow is inconsistent. The adrenaline bolus groups had transient increases in CBF after each bolus, but the infusion group had higher CBF overall ( p < 0.01). The effect on CBF of bolus adrenaline compared with an infusion was evaluated in 24 pigs that were randomised to receive either boluses of adrenaline every 3 min (20 μg/kg) or a bolus (20 μg/kg) followed by an infusion (10 μg/kg/min). The higher lactate values associated with administration of adrenaline could reflect either increased myocardial oxygen demand and/or stimulation of glycolysis. There was no significant difference between the groups in ATP values but the adrenaline group had a higher lactate concentration in the epicardium (6.3 ± 0.6 vs 4.2 ± 0.6 nmol/mg, p < 0.05, with a rise from baseline of 5.6 ± 0.5 vs 3.8 ± 0.5 nmol/mg, p < 0.05). The dogs were allocated randomly into two groups-those that received CPR alone and those that also received adrenaline (1 mg bolus then 0.2 mg/min). In a study of 20 adult dogs, coronary, cerebral and renal blood flow were measured, and cardiac tissue samples were taken for lactate concentration and myocardial adenosine 5′-triphosphate (ATP). Neuronal injury and signs of disruption to the blood–brain barrier were both greater in the adrenaline group. Although the adrenaline with vasopressin group had higher mean blood pressure ( p = 0.03) and CBF ( p < 0.05) during CPR, after resuscitation the CBF was numerically 36% lower, although this was not statistically significant ( p = 0.06). ![]() In another study, piglets were randomised to vasopressin, or vasopressin and adrenaline, with the adrenaline given by bolus (20 μg/kg) followed by infusion (10 μg/kg/min). Injection of adrenaline reduced microcirculatory blood flow ( p < 0.05), which persisted for several minutes. Six of the pigs received 1 mg of adrenaline after 1 min of precordial compression. Microcirculatory blood flow was assessed in the sublingual mucosa at regular intervals, and CPP was also recorded. This was also observed in a separate study where 15 pigs were subjected to 5 min of VF, and 5 minutes of precordial compression before electrical defibrillation was attempted. Microcirculatory blood flow was lower in the adrenaline groups than the placebo group after resuscitation ( p < 0.01). The pigs receiving bolus adrenaline (30 μg/kg) achieved a higher mean aortic pressure than those given placebo during and after CPR ( p < 0.05), but had lower PbO 2 values ( p < 0.01) and higher PbCO 2 values ( p < 0.01) after resuscitation. In another study by the same group, cerebral blood flow (CBF assessed with microcirculatory imaging), cerebral oxygen tension (PbO 2), and carbon dioxide tension (PbCO 2) were measured in four groups of five pigs. Post-resuscitation microvascular flows and cerebral oxygen tension (PbO 2) were higher and cerebral carbon dioxide tension (PbCO 2) lower after vasopressin compared with adrenaline. Microcirculatory blood flow was evaluated with orthogonal polarization spectral imaging in ten pigs that were randomised to receive either adrenaline 30 μg/kg or vasopressin 0.4 units/kg during CPR. A six-pig study measuring cerebral, coronary, and aortic pressures and blood flow identified that injection of 40 μg/kg of intravenous (IV) adrenaline significantly increased mean aortic pressure (29 ± 5 vs 42 ± 12 mmHg, p = 0.01), cerebral perfusion pressure (12 ± 5 vs 22 ± 10 mmHg, p = 0.01) and coronary perfusion pressure (8 ± 7 vs 17 ± 4 mmHg, p = 0.02), but mean coronary blood flow decreased (29 ± 15 vs 14 ± 7.0 mL/min, p = 0.03). These two groups, however, had lower SpO 2 values and lower cerebral tissue oximetry values than the placebo group, consistent with reduced organ and brain perfusion. A study of 36 adult pigs, which were randomised to one of two adrenaline doses (20 or 30 μg/kg) or to placebo, bolused every 3 minutes, documented increased arterial blood pressure and increased CePP in the adrenaline groups. ![]()
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