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Biomedical subjects

B M Holland

Publications and source records attributed to B M Holland.

At least 19 recordsLinked to original sources
PubMed2004

Is it possible to predict the blood volume of a sick preterm infant?

OBJECTIVE: To investigate the relation between the measured intravascular blood volume (BV) and current methods of indirectly assessing BV status in sick preterm infants on the first day of life. METHODS: Thirty eight preterm infants of gestation 24-32 weeks (median 30) and weight 480-2060 g (median 1220) were studied. Red cell volume was measured by the fetal haemoglobin dilution method in six infants and by the biotin labelled autologous red cell dilution method in the remaining 32. Total BV was calculated by dividing red cell volume by packed cell volume. Indirect assessments of BV status using heart rate (HR), core-peripheral temperature difference, mean arterial pressure, base excess, and packed cell volume were recorded. RESULTS: The mean (SD) initial measured BV was 71 (12) ml/kg (range 53-105). The mean HR was 148 beats/min (range 130-180), which correlated positively (r = 0.39, p = 0.02) with BV (higher HR was associated with higher BV). The mean base excess was -3.19 mmol/l (range -18 to +6.2). The negative base excess correlated significantly positively (r = 0.41, p < 0.01) with BV (more acidotic babies tended to have higher BV). There was no significant correlation between core-peripheral temperature difference, mean arterial pressure, or packed cell volume and BV. Regression analysis showed that base excess and HR were significantly related to BV; base excess alone can predict variability in BV only to 17%, and base excess with HR can predict variability in BV to 29%. CONCLUSION: The conventional clinical and laboratory indices are poor predictors of measured blood volume.

Blood Volume↗
PubMed1995

Recombinant haemopoietic growth factors in the newborn--will they be useful?

In vivo, realisation of the physiological reserve capacity of haemopoiesis depends on stimulation by cytokines, growth factors produced by autologous blood mononuclear cells. These cytokines include erythropoietin, granulocyte/macrophage colony stimulating factors, and thrombopoietin. In preterm infants, inadequate haemopoietic growth factor production limits haemopoiesis in its response to demands for extra blood cell production in stress situations. Haemopoiesis may also be inhibited by inflammatory disease and by nutritional deficiencies. In infants in intensive care, losses of blood, which contain haemopoietic stem cells and other progenitors, may also impair blood cell production. Recombinant haemopoietic growth factors promise to prevent or correct in part, this haemopoietic inadequacy. Verification of their therapeutic roles depends on further improvements in management of the preterm infant. These improvements include the optimisation of nutritional support and, especially, in terms of the endowment of blood from the placenta at birth, which strongly influences clinical outcome.

Hematopoiesis↗
PubMed1995

The roles and vital importance of placental blood to the newborn infant.

At 30 weeks' gestation, half of the approximately 110 ml/kg total blood volume (BV) of the feto-placental circulation is in the fetus, rising, by term, to about 90 ml/kg. In preterm infants at birth, subnormal blood volume is the rule, because of immediate cord clamping. Blood volume, typically 50-60 ml/kg during critical care, limits systemic oxygen (O2) transport and, because of shunting, causes hepato-splanchnic ischaemia and impaired lung function. Haemoconcentration results from plasma extravasation because of vascular endothelial damage. This elevates the haematocrit, masking the red cell lack. By allowing placental transfusion at birth, delaying cord clamping by 30-60 seconds, initial oligovolaemia is obviated, and post-natal lung adaptation greatly facilitated. The complications and costs of care can thereby be much reduced. Losses of haemopoietic stem cells are reduced, vital for haematologic and immunologic constitution and for response to haemopoietic growth factors. Further work is urgently needed to determine how to optimize this vital opportunity in preventive medicine in perinatology, with the objective of preventing complications, and reducing costs of all kinds, in management of the infant born preterm.

Blood Volume↗
PubMed1993

Umbilical cord clamping and preterm infants: a randomised trial.

OBJECTIVE: To investigate the clinical effects of regulating umbilical cord clamping in preterm infants. DESIGN: A prospective randomised study. SETTING: The Queen Mother's Hospital, Glasgow. SUBJECTS: 36 vaginally delivered infants over 27 and under 33 weeks' gestation. INTERVENTION: Holding the infant 20 cm below the introitus for 30 seconds before clamping the umbilical cord ("regulated" group, 17 patients), or conventional management ("random" group, 19 patients). MAIN OUTCOME MEASURES: Initial packed cell volume, peak serum bilirubin concentrations, red cell transfusion requirements, and respiratory impairment (assessed by ventilatory requirements, arterial-alveolar oxygen tension ratio over the first day in ventilated infants, and duration of dependence on supplemental oxygen). RESULTS: There were statistically significant differences between the two groups in mean initial packed cell volume (regulated group 0.564, random group 0.509) and median red cell transfusion requirements (regulated group zero, random group 23 ml/kg). 13 infants from each group underwent mechanical ventilation and showed significant differences in mean minimum arterial-alveolar oxygen tension ratio on the first day (regulated group 0.42, random group 0.22) and in median duration of dependence on supplemental oxygen (regulated group three days, random group 10 days). Differences in final outcome measures such as duration of supplemental oxygen dependence and red cell transfusion requirements were mediated primarily through arterial-alveolar oxygen tension ratio and also packed cell volume. CONCLUSIONS: This intervention at preterm deliveries produces clinical and economic benefits.

Bilirubin↗
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↗
PubMed1990

Total circulating red cells versus haematocrit as the primary descriptor of oxygen transport by the blood.

Peripheral haematocrit (PCV) is the traditional target and monitor in many transfusion regimens. Without negating the importance of PCV as a determinant of whole blood viscosity, the present article outlines two important reasons why the red cell volume (RCV) should replace PCV in the central target role during blood transfusion in intensive care and other emergency situations: 1. PCV reflects both RCV and plasma volume (PV) and is therefore not directly proportional to the total blood oxygen carrying capacity. At best, the relationship between PCV and RCV is hyperbolic and this is often overlooked when relating the two parameters in practice. At worst, the hyperbolic relationship is unreliable because PV and RCV can vary independently and the PCV is a fluctuating ratio of variable numbers. 2. PCV is not a good indicator of blood volume (BV), which is another important determinant of oxygen delivery to tissues and a crucial parameter in intensively managed patients. BV is directly proportional to RCV and this relationship also is often overlooked in clinical practice. The recommended values for RCV are 30 ml/kg in men. 25 ml/kg in women and between 30 ml/kg and 45 ml/kg in neonates within the first week of life.

Adult↗
PubMed1990

Increased concentrations of D-dimers in newborn infants.

The concentrations of D-dimers (the D fragments of fibrinogen) were measured in blood from 15 preterm infants, and 45 born at full term, to establish normal ranges. The adult normal range is less than 0.25 mg/l; 31 of the 60 infants (52%) had values less than 0.25 mg/l, in 16 (27%) they were 0.25-0.5, in eight (13%) 0.5-1, in three (5%) 1-2, and in two (3%) 2-4. D-dimer concentrations measured during the neonatal period should be interpreted with caution.

Fibrin Fibrinogen Degradation Products↗
PubMed1990

Biotin labeling of red cells in the measurement of red cell volume in preterm infants.

Determination of circulating red cell volume (RCV) in anemic preterm infants is, in theory, a better indicator of transfusion needs than Hb concentration. Our study reports the results of RCV measurement using biotin labeling of red cells on 40 occasions in preterm infants of 25-34 wk gestation. In 20 infants, who had estimations made within 24 h of birth, the RCV varied between 17.7 and 66 mL/kg. Twenty measurements were made at a later age at the time of a blood transfusion. RCV values were between 13.1 and 41.5 mL/kg before transfusion. In 13 infants, RCV was determined simultaneously using two methods, biotin and dilution of autologous HbF with donor HbA at transfusion. There was no significant difference between the results of RCV estimations using these two methods. Our study demonstrates that biotin labeling is an effective method for determining RCV in preterm infants.

Biotin↗
PubMed1988

Definitive estimate of rate of hemoglobin switching: measurement of percent hemoglobin F in neonatal reticulocytes.

The transition from fetal to adult erythropoiesis starts at 32-36 wk postconception. The rate of this switchover has been controversial. Studies of globin chain synthesis by reticulocytes in vitro have indicated gradual switching with a time for 50% reduction in fetal Hb synthesis ("half-time") of more than 6 wk. This may not accurately reflect fetal/adult Hb synthetic balance in vivo. By contrast, histochemical studies and also indirect mathematical analysis of postnatal changes in circulating fetal Hb and adult Hb may imply abrupt patterns of switching with half-times of less than 1 wk. We have resolved this discrepancy by direct measurement of the changing proportions of fetal and adult Hb in reticulocytes prepared by flourescence activated cell sorting from 10 full-term cord and 45 preterm postnatal blood samples. This method overcomes problems both of extrapolation from in vitro measurements and of mathematical analysis. We find a gradual transition from fetal Hb to adult Hb synthesis. The half-time is approximately 16-18 wk. Values of fetal Hb in reticulocytes were on average higher than predicted from in vitro synthesis studies. We find considerable individual variation. Infants differ in their switching behaviour, many showing prolonged dependence on fetal Hb.

Age Factors↗
PubMed1987

Lessons from the anemia of prematurity.

In our view, three main lessons stem from consideration of the refractory early anemia of prematurity (REAP). These are: (1) Hemoglobin concentration is not enough to describe the anemia. (2) The REAP may be clinically very severe but is often easily missed. It interacts with and worsens other causes of anemia in preterm infants, such as blood losses. Its pathogenesis is multifactorial, but it is generally interrelated with short gestation and its other complications. (3) Prevention, prophylaxis, and if necessary, adequate management are very important.

Anemia, Neonatal↗
PubMed1986

Outbreak of Salmonella eimsbuettel in newborn infants spread by rectal thermometers.

Over a six-week period there were 25 episodes of Salmonella eimsbuettel infection in newborn infants, mothers, and staff in a modern maternity hospital with 3600 annual deliveries. The probable source was a mother and her child, and the organism was spread by rectal thermometers in the labour suite and one of the wings (wards). When the thermometers were withdrawn from use and correctly disinfected the outbreak in babies ceased. Environmental cross-infection of staff was halted by closure, cleaning, and disinfection of the clinical area mainly affected. Some babies had diarrhoea but quickly recovered, and none came to harm. The infected staff had no symptoms and returned to duty after three negative cultures. Measurement of temperature is still an important observation in the care of newborn infants, but for everyday care it is recommended that rectal thermometry be discontinued and replaced by axillary measurement.

Cross Infection↗
PubMed1986

Determination of red-cell mass in assessment and management of anaemia in babies needing blood transfusion.

A new method for the rapid determination of red-blood-cell mass (RCM) in infants needing blood transfusion is described. RCM is estimated from the fall in the baby's fetal haemoglobin level resulting from transfusion of a known mass of adult-haemoglobin-containing red cells. In severe blood loss and refractory anaemias in preterm infants, in addition to the red-cell deficit, the plasma volume is low, leading to a falsely high haematocrit of about 0.30, which conceals a deficiency of 50-70% in circulating red cells. Red-cell transfusion in such infants based on haematocrit often fails to restore RCM to normal, leading to repeated transfusions. The frequency of transfusions may be reduced by giving enough red cells fully to correct the deficiency based on RCM estimation.

Adult↗
PubMed1985

The flow of blood cell suspensions through 3 microns and 5 microns Nuclepore membranes: a comparison of kinetic analysis with scanning electron microscopic examinations.

This study was designed to investigate the effect of red and white cells on the flow of dilute suspensions of blood cells through 3 microns and 5 microns Nuclepore membrane filters. The rate of flow of blood cell suspensions through 3 microns or 5 microns membranes declines continually due to occlusion of pores by slow cells. The cells which occlude 3 microns pores exceed the number of white cells about seven-fold. Electron microscopic examination of a used membrane confirms that these slow cells are not white cells but are red cells which are visibly damaged. With 5 microns membranes, the number of slow cells is entirely consistent with them being white cells. Again, electron microscopic examination confirms that 5 microns pores are occluded by white cells. With both types of membrane, the same kinetic analysis is valid and yields information about the behaviour of red cells during the filtration procedure.

Blood Cells↗