PubMed Health⌕ Search

Biomedical subjects

M Smithies

Publications and source records attributed to M Smithies.

6 recordsLinked to original sources
PubMed1989

Continuous high volume venous-venous haemofiltration in acute renal failure.

Continuous, high volume, venous-venous haemofiltration was used as renal support in 28 critically ill patients with acute renal failure. Fifteen patients survived and were subsequently discharged from the ITU. Although haemofiltration was highly effective in reducing the blood urea and serum creatinine, only survivors demonstrated a significant increase in arterial pH (medians before and at two days 7.28 and 7.49 respectively, p less than 0.005) with a reduction in severity of their illness (median APACHE II scores before and at two days 23 and 16, p less than 0.005). Patients who died remained severely ill and acidotic (median APACHE II scores before and at two days 26 and 28; median arterial pH values 7.32 and 7.31 respectively) and by day two of treatment, marked differences between the patient groups in APACHE II scores, mean arterial pressure, arterial pH and urine flow rate had developed. Haemofiltration with the correction of acute uraemia alone does not necessarily lead to a reduction in the severity of illness which in the critically ill more frequently reflects other organ dysfunction.

Acute Kidney Injury↗
PubMed1987

The effects of vasodilation with prostacyclin on oxygen delivery and uptake in critically ill patients.

We hypothesized that inadequate oxygenation of peripheral tissues may be unrecognized in critically ill patients and may worsen their prognosis. To test this hypothesis, we measured oxygen delivery to tissues, oxygen uptake, and the extraction ratio (uptake/delivery) before and during a 30-minute infusion of a vasodilator, prostacyclin (5 ng per kilogram of body weight per minute), in 27 critically ill patients with acute respiratory failure. Prostacyclin produced an increase in oxygen delivery (median value before vs. during infusion, 375 vs. 492 ml of oxygen per minute per square meter of body-surface area, P less than 0.001) that was similar in the 14 patients who survived and the 13 who died. This increase in oxygen delivery was associated with a significantly greater increase in oxygen uptake in the patients who died as compared with the survivors (median increase, 19 vs. 5 percent, P less than 0.001). In the survivors, the oxygen extraction ratio fell (median change, -17 percent; range, -27 to -6 percent) and the mixed venous oxygen tension increased. In the patients who died, the extraction ratio rose (median change, 11 percent; range -24 to +40 percent) and the mixed venous oxygen tension did not change. These data suggest the presence of a substantial oxygen debt in patients who subsequently die. Inadequate tissue oxygenation, which may be difficult to recognize, appears to be an important mechanism contributing to the development of irreversible multiple organ failure and subsequent death in some patients with acute respiratory failure.

Acute Disease↗
PubMed1987

A comparison of direct and indirect measurements of oxygen delivery and consumption: the effects of prostacyclin in two human volunteers.

To examine the relation of oxygen delivery to uptake in normals, we have measured cardiac index, oxygen delivery and oxygen consumption directly and indirectly in two human volunteers before and during a prostacyclin (PGI2) infusion (5 ng/kg/min). We have also investigated the relation of direct and indirect measurements of delivery to consumption in two critically ill patients over a more prolonged study period of 24 hours. Overall, there were close correlations between both cardiac index measured by thermodilution with that calculated from the Fick equation (r = 0.97 p less than 0.001) and oxygen consumption measured directly by analysis of inspired gases (V O2) with that calculated by the reverse Fick method (OUI) (r = 0.95 p less than 0.001). Nevertheless, the limits of agreement between the two methods were wide (1.6 L/min.m2 for the cardiac index and 70.5 ml 02/min.m2 for oxygen consumption, 95% confidence limits). In the two human volunteers, PGI2 produced substantial increases in oxygen delivery but there was no change in oxygen consumption measured directly or indirectly; V O2 and OUI were unrelated and independent of oxygen delivery. However, in the two patients studied over 24 hours, there were close correlations between delivery and both V O2 (r = 0.93 p less than 0.001) and OUI (r = 0.94 p less than 0.001). These results suggest that the derivation of oxygen consumption by the reverse Fick method (OUI) is a reasonable substitute for direct measurements of V O2 but occasionally the absolute values so obtained may be somewhat different.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗