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Biomedical subjects

C A Wardrop

Publications and source records attributed to C A Wardrop.

14 recordsLinked to original sources
PubMed1992

Reduced haemoglobin levels in infants presenting with apparent life-threatening events--a retrospective investigation.

Anaemia has been shown to be associated with an increased apnoeic pause frequency and with cyanotic breath-holding spells. In this study, the relationship between anaemia and apparent life-threatening events was retrospectively investigated in 72 term infants referred for assessment and home monitoring following an apparent life-threatening event. For 41 infants (25 male, 16 female; 38 Caucasian, three Asian) a venous red blood cell count was available. Their median age at the time of the apparent life-threatening event was 2.0 (0.6-6.7) months. The Hb levels in these 41 infants were plotted against normal data from the literature. Thirty-four infants had Hb levels below the mean, whilst six infants had values above the corresponding normal mean; the one remaining infant had a Hb value identical to the normal mean. Significantly more infants than expected had Hb levels below the mean (p less than 0.001, binomial test). Anaemia may have played a role in the pathophysiology leading to life-threatening events in some of the infants investigated in this study.

Age Factors↗
PubMed1992

Optimization of the blood for oxygen transport and tissue perfusion in critical care.

In present practice, patients in intensive care are managed with subnormal haematocrit values and oligovolaemia. Optimization of the blood for oxygen transport in preterm infants in intensive care yields major benefits in their prognosis. A rational basis is described for this optimization in terms of the circulating blood volume and haematocrit, represented by circulating red cell volume (mass). Extrapolation of these lessons in haematological management is proposed for adult patients in critical care, so as to reduce dependence on respiratory support and minimize clinical complications and costs.

Adult↗
PubMed1979

Effects of stopping smoking for 48 hours on oxygen availability from the blood: a study on pregnant women.

The effects of stopping smoking for 48 hours on factors governing the availability of oxygen from the blood--that is, carboxyhaemoglobin (COHb), haemoglobin-oxygen (HbO2) affinity, and haemoglobin concentration--were measured in women in the last trimester of pregnancy. Three groups were studied: smokers, smokers who stopped smoking for 48 hours, and non-smokers. The 22 smokers had higher initial COHb values and greater HbO2 affinity than the 10 non-smokers, but their total haemoglobin concentrations were also higher, so that their oxygen availability was not significantly reduced. In the 11 smokers who stopped the reduction in COHb and decrease in HbO2 affinity led to a significant increase of 8% in "available oxygen" in 48 hours. Since even small improvements in oxygen delivery to the tissues may confer critical benefit to the fetus, particularly during labour or when exposed to general anaesthesia, smoking should be discouraged for 48 hours before elective deliveries. The same consideration might reasonably be applied to patients undergoing general anaesthesia for all elective operations.

Carboxyhemoglobin↗
PubMed1978

Oxygen availability from the blood and the effect of phosphate replacement on erythrocyte 2,3-diphosphoglycerate and haemoglobin-oxygen affinity in diabetic ketoacidosis.

Eleven patients with diabetic ketoacidosis were given intravenous phosphate in doses (mean 118 mmol; range 83--320 mmol) adequate to maintain normal plasma phosphate, in addition to a standard treatment regime. Prevention of hypophosphataemia stimulated recovery of the initially low red-cell 2,3-diphosphoglycerate concentrations (10.6 +/- 5.8 (SD) mumol/g Hb) after twenty-four hours. In ten control patients (initial concentration 8.1 +/- 4.4 mumol/g Hb) treated without phosphate replacement, significantly lower red-cell 2,3-diphosphoglycerate concentrations were found between 2 and 6 days after admission (forty-eight hour value for control patients 14.6 +/- 1.6 and for phosphate-treated patients 18.9 +/- 4.1 mumol/g Hb; p less than 0.01). However, no effect on in vivo p 50 or on the availability of oxygen from the blood resulted from the higher 2,3-diphosphoglycerate levels. Maintenance of normal plasma phosphate levels by intravenous phosphate is, therefore, not indicated to improve tissue oxygenation in diabetic ketoacidosis.

Adolescent↗
PubMed1978

Nonphysiological anaemia of prematurity.

Clinical and haematological findings at the nadir of the refractory, early anaemia of prematurity were compared in a study of 95 preterm infants. 53% of 30 babies less than 32 weeks' gestational age at birth had abnormal clinical features resulting from anaemia at its nadir, with a combination of tachycardia, tachypnoea, dyspnoea and feeding difficulties, diminished activity, and pallor. The expression 'available oxygen', derived from the Hb concentration and Hb-O2 affinity, correlated more closely with clinical features of anaemia that did the Hb concentration alone. A formula is presented that predicts the 'available oxygen', provided the Hb concentration and post-conceptual age are known; this avoids the need for direct measurement of Hb-O2 affinity. Clinical anaemia is common in preterm infants with Hb concentrations of up to 10.5 g/dl, consequent on the high O2 affinity of fetal Hb. This is the first description of any common clinical consequence of high Hb-O2 affinity.

Age Factors↗
PubMed1978

Simple and versatile method for measuring oxygen consumption in infants.

A simple, rapid, and accurate method for measuring oxygen consumption in infants is described. Expired gas is entrained in a stream of air drawn through a gently applied face mask. Oxygen consumption is derived from (1) gas flow rate, measured with a flowmeter, and (2) the fall in oxygen concentration of the gas mixture, measured with a paramagnetic analyser. A measurement can be made at the bedside within 2 minutes without disturbing the infant. In 17 mature 2-day-old neonates mean oxygen consumption was 6.52 ml/kg per min, SD 0.90, similar to that previously reported using less simple methods,

Evaluation Studies as Topic↗
PubMed1977

Acute folate deficiency associated with intravenous nutrition with aminoacid-sorbitol-ethanol: prophylaxis with intravenous folic acid.

Preoperative folate levels were initially normal in 30 patients with gastrointestinal tract disease but fell within 48 h by 60-95% in 20 patients who received intravenous nutrition for 6-12 d with aminoacid-sorbitol-ethanol (ASE). This depression persisted in patients not given folate supplements. Folate levels in 10 control patients not given ASE showed only minimal decline. Haematological changes were reduced to a minimum in 10 patients given 0.5 mg i.v. folic acid daily whilst eight unsupplemented patients showed evidence of megaloblastic haemopoiesis. Three of these eight patients developed thrombocytopenia and/or leukopenia which was fatal in one patient.

Aged↗
PubMed1975

Acute folate deficiency in surgical patients on aminoacid/ethanol intravenous nutrition.

Acute folate deficiency with pancytopenia and megaloblastic haemopoiesis developed in four patients after abdominal operations; all four responded to folic acid over 3-9 days. Three of them had been given intravenous nutrition with amino-acid/ethanol before the blood changes developed. A prospective study of twenty-five surgical patients with gastrointestinal diseases revealed a high frequency of acutely developing negative folate balance. Megaloblastic haemopoiesis and consequent blood changes were found in five patients. Treatment with intravenous nutrition correlated strongly with a fall in serum-folate and megaloblastic haemopoiesis. Some surgical patients develop acute folate deficiency which may proceed to megaloblastic arrest of haemopoiesis. Patients receiving intravenous nutrition containing ethanol are especially prone to this complication, which may be life-threatening if untreated. It is not yet known whether other forms of intravenous nutrition carry a similar risk.

Acute Disease↗
PubMed1975

Immunological abnormalities in splenic atrophy.

Multiple immunological abnormalities have been demonstrated in fourteen patients with evidence in the blood-film of hyposplenism due to splenic atrophy. Reduction in spleen size was confirmed radiologically, and impairment of phagocytosis by the spleen was demonstrated by studying the survival and fate of chemically damaged autologous red blood-cells. Eight of the patients had intestinal malabsorption, and there was a high frequency of autoimmune disease in the remainder. Although patients with splenic atrophy showed little evidence of impairment of normal immune responses, there was a high frequency of autoantibody formation. There is thus an association between widespread immunological disturbances, notably autoimmunity, and splenic atrophy.

Adult↗