The haemodynamic effects of intermittent haemofiltration in critically ill patients.

The haemodynamic effects of intermittent high volume venovenous haemofiltration were studied in 13 critically ill patients. The mean negative fluid balance during filtration was 1.21 and the mean duration of treatment 3 h 40 min. The cardiac index fell initially (4.5 +/- 0.2 to 3.8 +/- 0.21/min/m2; p less than 0.05) but then remained stable throughout treatment before returning to baseline at the end of haemofiltration. The mean arterial pressure was unchanged with an increase in the systemic vascular resistance (651 +/- 33 to 765 +/- 65 dyne.s/cm5; p less than 0.05) suggesting that vascular responsiveness is maintained during haemofiltration.

Adrenaline in treatment of septic shock: effects on haemodynamics and oxygen transport.

The effects of adrenaline on haemodynamics and oxygen transport were studied in 13 patients with septic shock persisting after optimal fluid loading. Adrenaline was administered by intravenous infusion at an increasing dose until no further benefit was seen. There were significant increases in mean arterial pressure, cardiac index, left ventricular stroke work index and oxygen delivery index. There was no significant change in oxygen consumption although the trend was towards an increase. There was a significant reduction in oxygen extraction ratio, but no change in shunt fraction. Adrenaline would appear to have beneficial haemodynamic effects in septic shock.

Pulmonary function tests before and after laparoscopic cholecystectomy.

Pulmonary function tests were performed in 22 patients undergoing laparoscopic cholecystectomy. Measurements were made before, 24 h after, and 6 weeks after operation (12 patients). At 24 h postoperatively there were significant decreases in forced expiratory volume in 1 s, vital capacity, functional residual capacity and total lung capacity to 75% (p < 0.001), 73% (p < 0.001), 92% (p = 0.002) and 83% (p < 0.001) of pre-operative values respectively. Inspiratory and expiratory mouth pressures decreased to 66% (p < 0.001) and 63% (p < 0.001) of the pre-operative pressures respectively. There was a reduction in PaO2 (p < 0.01) and an increase in alveolar-arterial gradient (p < 0.001) but no change in PaCO2 at 24 h. The pulmonary function tests measured in the patients who returned after 6 weeks had returned to pre-operative values.

Spinal anesthesia with tetracaine--effect of added vasoconstrictors.

The effect of adding 0.2 ml of 1:1000 epinephrine or 0.5 ml of 1% phenylephrine to 1.5 ml of 1% tetracaine for spinal anesthesia was assessed in 30 patients in a double-blind study. Phenylephrine but not epinephrine produced a significant prolongation of sensory loss in the T12 dermatome. Both vasoconstrictors produced a significant prolongation of the total duration of sensory and motor blockade. These findings differ from those in previous studies in which lidocaine and bupivacaine were used.

Cerebral blood flow and metabolism in patients with chronic liver disease undergoing orthotopic liver transplantation.

Changes in cerebral hemodynamics and metabolism associated with anesthesia and liver transplantation may present particular hazards for patients with cirrhosis. Fifteen patients undergoing liver transplantation were studied, 7 of whom had encephalopathy. Cerebral blood flow (CBF) was measured at the start of surgery, during veno-venous bypass and post reperfusion, using a method based on the Kety-Schmidt method. Cerebral metabolism was assessed by measuring the cerebral metabolic rate for oxygen (CMRO2) and the lactate oxygen index (LOI). The cerebral vascular reactivity to carbon dioxide (CO2) was studied during the preanhepatic and post reperfusion phases. During the preanhepatic period, the median CBF was 44 mL/100 g/min at an arterial carbon dioxide tension (PaCO2) of 3.8 kPa. After reperfusion the CBF increased (P < .02) to 102 mL/100 g/min, the arterial hydrogen ion concentration increased from 39 nmol/L to 53 nmol/L (P < .02) and the jugular venous oxygen saturation from 74% to 89% (P < .02). CBF was similar in patients with and without encephalopathy. The cerebral vascular reactivity to CO2 remained intact, although after reperfusion, the CBF for a given PaCO2 was greater, and the slope of the CBF/CO2 response curve diminished. The CMRO2 was normal in patients without encephalopathy. In the encephalopathic patients, the CMRO2 was low during all stages of transplantation (0.54, 0.86, 1.24 mL/100 g/min, respectively). Patients with encephalopathy may be at increased risk of hypoxemic brain injury during transplantation. To minimize this possibility, more detailed neurological monitoring may be useful.

The relationship of blood lactate concentrations, oxygen delivery and oxygen consumption in septic shock and the adult respiratory distress syndrome.

Tissue hypoxia is thought to be pivotal to the development of multiple organ failure, but cannot be measured directly in clinical practice. We assessed the relationship between initial arterial blood lactate concentrations and the presence of the phenomenon of delivery-dependent oxygen consumption, both of which may indicate tissue hypoxia. Twenty-three critically ill patients with septic shock and adult respiratory distress syndrome were studied prospectively and allocated to one of two groups according to blood lactate concentrations. In group 1, blood lactate concentration was less than the level widely accepted as significant (2 mmol.l-1); in group 2, the concentration exceeded 2 mmol.l-1. In both groups, resuscitation with colloid, blood and vasoactive drugs resulted in significant increases in oxygen delivery; in group 1 (n = 13), mean (SEM) oxygen delivery increased from 484 (36) to 730 (44) ml.min-1.m-2 (p < 0.005) and in group 2 (n = 10) from 550 (54) to 780 (54) ml.min-1.m-2 (p < 0.05). In neither group was there a significant change in oxygen consumption. However, there were individuals in both groups who exhibited pathological delivery dependence. This suggests that the absence of hyperlactataemia does not preclude delivery dependence of oxygen consumption with the attendant potential for tissue hypoxia.