Less invasive determination of cardiac output from the arterial pressure by aortic diameter-calibrated pulse contour.

BACKGROUND: Cardiac output by modelflow pulse contour method can be monitored quantitatively and continuously only after an initial calibration, to adapt the model to an individual patient. The modelflow method computes beat-to-beat cardiac output (COmf) from the radial artery pressure, by simulating a three-element model of aortic impedance with post-mortem data from human aortas. METHODS: In our improved version of modelflow (COmfc) we adapted this model to a real time measure of the aortic cross-sectional area (CSA) of the descending aorta just above the diaphragm, measured by a new transoesophageal echo device (HemoSonic 100). COmf and COmfc were compared with thermodilution cardiac output (COtd) in 24 patients in the intensive care unit. Each thermodilution value was the mean of four measurements equally spread over the ventilatory cycle. RESULTS: Least squares regression of COtd vs COmf gave y=1.09x[95% confidence interval (CI) 0.96-1.22], R2=0.15, and of COtd vs COmfc resulted in y=1.02x(95% CI 0.96-1.08), R2=0.69. The limits of agreement of the un-calibrated COmf were -3.53 to 2.79, bias=0.37 litre min(-1) and of the diameter-calibrated method COmfc, -1.48 to 1.32, bias=-0.08 litre min(-1). The coefficient of variation for the difference between methods decreased from 28 (un-calibrated) to 12% after diameter-calibration. CONCLUSIONS: After diameter-calibration, the improved modelflow pulse contour method reliably estimates cardiac output without the need of a calibration with thermodilution, leading to a less invasive cardiac output monitoring method.

Intravenous fenoldopam infusion in severe heart failure.

Fenoldopam, a selective DA1-receptor agonist, infused intravenously for 24 hours (0.6 +/- 0.3 microgram/kg/min, range 0.1-1.5) in 25 patients with NYHA functional class III or IV heart failure, produced a prompt and sustained hemodynamic response. Cardiac index rose from an average preinfusion baseline value of 1.8 to 2.6/l min. Stroke volume index increased from 19 to 26 ml/m2 and stroke work index increased from 18 to 25 g M/m2. These changes were accompanied by a reduction in systemic vascular resistance from an average of 2400 to 1500 dynes sec/cm5. There was no change in the heart rate or right atrial pressure. There was a transient reduction in the left ventricular filling pressure from 25 to 20 mmHg. Urinary sodium excretion did not change significantly. Transient asymptomatic thrombocytopenia developed in four patients. The drug was well tolerated by all patients. These results suggest that continuous intravenous infusion of fenoldopam is safe and produces favorable hemodynamic responses in severe heart failure. However, unlike its effects in patients with hypertension, it failed to produce sustained natriuresis in these patients.

[The relationship between creatinine clearance and glomerular filtration rate in the critically ill patient]. / Die verband tussen kreatinienopruiming en glomerulêre filtrasiespoed in die kritiek siek pasiënt.

A study was undertaken to show that the determination of glomerular filtration rate with radio-labelled sodium chromate ethylenediaminetetra-acetic acid is a repeatable, easily performed and accurate examination in the critically ill patient. Differences in glomerular filtration rate were relatively small, with a phase difference of between -10,59 and 5,34. Creatinine clearance showed a greater variation over a corresponding period, with a difference of between -27,50 and -4,10. The study indicated that this method of determining glomerular filtration rate can be very useful in an intensive care unit, because it seems to be more accurate and easier to perform. Information is obtained more quickly than when the glomerular filtration rate is determined by means of creatinine clearance.

An electronic apparatus for early detection of changes in red cell content of blood during anaesthesia. A preliminary report.

An electronic apparatus was developed for anaesthetists to use to detect changes in red cell concentration during surgery. The mechanism is based on the relationship between the red cell content and the electrical conductivity of blood. In a pilot study of 170 blood samples, a correlation coefficient of 0.9806 was obtained between haematocrit and the instrument readings. To evaluate the instrument's performance in practice, and factors that might influence its readings, a series of 10 cases of aortic surgery were investigated. It is concluded that, although changes in electrolyte concentration, pH and temperature do affect the instrument's readings, these are insignificant compared with those of red cell content, and that the device can be used to indicate a drop in red cell concentration.

Ingestion of codeine and salicylic acid causing convulsions and coma. A case report.

A 3-year-old White child was admitted to the critical care unit in a coma after a generalized convulsion. Codeine and salicylic acid were present in his plasma. The possible aetiology and management are discussed.

Severe staphylococcal infection with pneumonia treated by plasmapheresis and plasma exchange. A preliminary report.

Three cases of extremely severe staphylococcal infection are reported. All 3 patients were treated by plasmapheresis and fresh plasma or fresh-frozen plasma replacement, and all made a steady recovery. In all 3 cases blood culture for Staphylococcus aureus was positive, 1 patient had osteitis, and 1 signs of spinal cord compression by an infectious process (an abscess). It is thought that the above mentioned procedures may offer a useful additional line of therapy for desperately ill patients with staphylococcus infections.