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Biomedical subjects

A M Weindling

Publications and source records attributed to A M Weindling.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cerebral oxygenation during cardiopulmonary bypass.

Cerebral fractional oxygen extraction (FOE) was monitored in 30 children, using near infrared spectroscopy during cardiopulmonary bypass, to investigate the effect of hypothermia and circulatory arrest. One group of children (n = 15) underwent profound hypothermia with total circulatory arrest (n = 8) or continuous flow (n = 7). Another group (n = 15), of whom only one had circulatory arrest, underwent mild (n = 6) or moderate (n = 9) hypothermia. The mean FOE (SD) before bypass was 0.35 (0.12) and this correlated negatively with the preoperative arterial oxygen content (r = -0.58). Between the stage of cooling on bypass and cold bypass there was a reduction in FOE in all groups. Between cold bypass and rewarming there was an increase in FOE only in the groups with continuous flow. In the circulatory arrest group, the FOE remained low during rewarming and was significantly lower than that of the continuous flow group. No patients died and none had neurological abnormalities postoperatively. Apparent changes in oxidised cytochrome oxidase concentration were also monitored using near infrared spectroscopy. There was a fall in cytochrome aa3 on starting cardiopulmonary bypass, but there were no significant differences in the changes in cytochrome aa3 between any stage in any of the patient groups. Using this non-invasive technique, cooling was shown to reduce cerebral FOE. During rewarming on bypass there was an increase in cerebral FOE only in patients who had had continuous flow bypass. In contrast, the cerebral FOE in those with circulatory arrest remained constant after arrest and during the duration of the study. This may have implications for the timing of hypoxic brain injury.

Adolescent↗
PubMed1998

Three year visual outcome for treated stage 3 retinopathy of prematurity: cryotherapy versus laser.

BACKGROUND/AIMS: In the management of retinopathy of prematurity (ROP), several studies have demonstrated laser photocoagulation to be as effective as cryotherapy in reducing the incidence of unfavourable structural outcome. However, few data are available on the functional outcome. The 3 year visual acuity outcome of infants treated with laser or cryotherapy in a neonatal unit is presented. METHODS: The case notes of 34 infants (64 eyes) treated with cryotherapy, between 1989 and 1992, and 32 infants (59 eyes) treated with laser, between 1992 and 1995, were reviewed. RESULTS: In the cryotherapy group 69% of eyes had a favourable structural outcome. Of these structurally successful eyes 62.5%, 35.0%, and 33.3% of eyes had visual acuities within normal limits at the 12 month, 24 month, and 36 month corrected age milestones respectively. In the laser group 93% of eyes had a favourable structural outcome. Of these structurally successful eyes 96.4%, 66.7%, and 59.5% of eyes had visual acuities within normal limits at the 12 month, 24 month, and 36 month corrected age milestones respectively. CONCLUSION: In the management of ROP, when laser photocoagulation induces a structurally successful result, the potential for normal visual acuity development at 3 years is high. Whether the poorer functional outcome of the eyes treated with cryotherapy is an artefact of the historical nature of the study or as a result of an adverse effect of the destructive transcleral application is unknown.

Child Development↗
PubMed1998

Peripheral oxygenation and anemia in preterm babies.

A measurement of tissue oxygenation may be a better marker of transfusion need than the Hb concentration. Peripheral fractional oxygen extraction, oxygen consumption, and oxygen delivery were measured noninvasively using near infrared spectroscopy in babies, some of whom were given blood transfusions. The above indicators of oxygenation were measured in 96 preterm babies. The decision to transfuse was based on a standard protocol. Transfusions were not considered necessary for babies in group 1 but were given to those in groups 2 (asymptomatic) and 3 (symptoms attributed to anemia). Hb and Hb fraction F (HbF) were measured in each baby. Oxygenation, Hb, and HbF measurements were made again 12-24 h after transfusion, and red cell volume (RCV) was calculated. Fractional oxygen extraction was significantly higher in symptomatic (0.43 +/- 0.06) but not asymptomatic (0.33 +/- 0.05) babies compared with control subjects (0.35 +/- 0.06). Oxygen consumption and oxygen delivery were similar in the three groups before transfusion. After transfusion the mean fractional oxygen extraction fell significantly in symptomatic but not in asymptomatic babies. There was no significant change in either oxygen consumption or oxygen delivery in symptomatic babies. The asymptomatic group had no change in oxygen extraction or oxygen consumption after transfusion, although oxygen delivery increased significantly. Fractional oxygen extraction correlated with HbF (n = 66, r = 0.49, p < 0.001) and RCV (n = 19, r = -0.48, p = 0.04) and there was a weak correlation with Hb (n = 94, r = -0.21, p = 0.04). Peripheral fractional oxygen extraction monitored noninvasively correlated with variables known to determine oxygen availability to the tissues, namely RCV and HbF, and was higher in babies with symptomatic anemia and decreased after transfusion.

Anemia↗
PubMed1998

Measurement of cerebral oxygen consumption in the human neonate using near infrared spectroscopy: cerebral oxygen consumption increases with advancing gestational age.

Measurements of cerebral oxygen consumption (CVO2) may improve our understanding of cerebral oxygenation, but there are few published data for sick neonates. Although cerebral maturation is associated with an increase in cerebral glucose consumption, the relationship between CVO2 and increasing gestational age has not previously been assessed in humans. The aims of this study were to evaluate a noninvasive method for the estimation of CVO2 in the neonate using near infrared spectroscopy, and to investigate the relationship between gestational age and CVO2. Twenty babies who were undergoing intensive care in the neonatal period were studied. Cerebral hemoglobin flow (CHbF) and cerebral venous oxyhemoglobin saturation (CSVO2) were measured using near infrared spectroscopy. Arterial oxyhemoglobin saturation was measure by pulse oximetry (SpO2). CVO2 was calculated from the equation: CVO2=CHbF x (SpO2 - SvO2 x 4. The median (range) CVO2 was 0.9 (0.52-1.76) mL x 100 g(-1) min(-1). There was an increase in CVO2 with advancing gestational age (n=20, p=0.55, p=0.014). We conclude that CVO2 can be estimated in sick neonates using noninvasive optical methods. The values obtained are similar to those obtained in other studies by more invasive methods, and are in agreement with values which would be expected from the known rate of cerebral glucose consumption in neonates. Mean (SD) CVO2 at 24-26 wk was 0.5 (0.18) mL x 100 g(-1) min(-1) and rose with increasing gestation to term by 0.03 mL x 100 g(-1) min(-1) per wk.

Anticonvulsants↗
PubMed1997

Measurement of venous oxyhaemoglobin saturation in the adult human forearm by near infrared spectroscopy with venous occlusion.

Measurement of the oxygenation of the peripheral tissues provides useful information about tissue perfusion. A method is described for the measurement of peripheral venous oxyhaemaglobin saturation (SvO2) in the adult forearm by a noninvasive technique, near infrared spectroscopy (NIRS) with venous occlusion. A series of studies is performed on healthy adults to compare measurements of forearm SvO2 made by NIRS with measurements of superficial venous SvO2 made by co-oximetry, and to study the effect of different optode spacings. There is a significant correlation between forearm SvO2 measured by NIRS and SvO2 of superficial venous blood measured by co-oximetry (n = 19, r = 0.7, p < 0.0001). Higher values for SvO2 were obtained using a 2.5 cm spacing than with a 4 cm spacing (mean difference = 4.1% (95% CI 1.4%-6.8%) n = 16). This difference is likely to have been due to a more superficial volume of tissue being studied with the closer optode spacing. Peripheral SvO2 can be measured non-invasively using NIRS with venous occlusion. It may prove to be a useful method to study circulatory disturbances.

Adult↗
PubMed1996

A randomized controlled trial of early physiotherapy for high-risk infants.

The aim of this study was to investigate the hypothesis that infants at high risk of cerebral palsy would benefit from early physiotherapy. In total, 105 infants with abnormal cranial ultrasound scans were randomized at around term to early physiotherapy or standard treatment (delaying physiotherapy until abnormal physical signs became apparent). At 12 and 30 months there were clinical and objective assessments. Nine infants died and nine were lost to follow-up by 12 months when 87 infants were assessed. One other child had died and three others were lost to follow-up by 30 months when 83 children were assessed. Cerebral palsy was only accurately predicted in 45 (54%) infants. There was no difference in outcome. The difficulty of predicting cerebral palsy reliably and the heterogeneity of the condition should be borne in mind when planning treatment and assessing its efficacy.

Cerebral Palsy↗
PubMed1996

The effect of a child's disability on mother's mental health.

The prevalence of maternal depression was investigated in the mothers of 96 children: 30 premature infants at risk for the development of cerebral palsy; 35 premature infants considered not to be at risk for the development of cerebral palsy; and 31 healthy fullterm infants. There were equally high levels of depression in all three groups of mothers, regardless of birth status, prediction of disability, or presence of actual disability, throughout the first year of the children's lives. Depressed mothers were, however, found to have significantly more psychosocial stress. An early physiotherapy intervention had no effect on the prevalence of depression in mothers whose children were at risk for the development of cerebral palsy.

Cerebral Palsy↗
PubMed1996

The measurement of peripheral venous oxyhemoglobin saturation in newborn infants by near infrared spectroscopy with venous occlusion.

A novel, noninvasive method for measuring peripheral venous oxygen saturation (Svo2) in newborn infants using near infrared spectroscopy (NIRS) with venous occlusion is described, along with a comparison with co-oximetry of peripheral venous blood. Peripheral Svo2 was measured in 16 newborn infants by NIRS with venous occlusion, and the results were compared with those obtained by co-oximetry of blood from a forearm vein. There was a significant correlation between the two measurements (r = 0.85, p < 0.0001) and close agreement between the two techniques (mean difference (co-oximeter-NIRS) 6%, limits of agreement-5.1% to 17.1%). Three different methods for analysis of the NIRS data were examined to determine which period during the venous occlusion provided the most accurate measurement. The agreement was the same for all methods of analysis.

Female↗
PubMed1995

Raised pulmonary artery pressure in very low birthweight infants requiring supplemental oxygen at 36 weeks after conception.

This study aimed to investigate the changes in pulmonary artery pressure in infants with chronic lung disease who then developed prolonged oxygen dependency. The time to peak velocity: right ventricular ejection time (TPV:RVET) ratio calculated from the Doppler waveform, which correlates negatively with pulmonary artery pressure, was used. Thirty four infants with chronic lung disease were studied. At 36 weeks after conception 19 infants still required supplemental oxygen (POD group) and 16 infants were in air (controls). Over the first three weeks, there was a significant rise in the ratio in both groups, indicating a fall in pulmonary arterial pressure. From the third week onwards the ratio was significantly lower in the POD group. There was a significant rise in the ratio from four to 36 weeks after conception in the control group; the POD group showed a tendency towards a fall over the same time period. The requirement for supplemental oxygen almost mirrored the changes in the ratio in both groups but was not significantly different until the fifth week after birth. These data suggest that pulmonary arterial pressure has a significant role in the pathophysiology of prolonged oxygen dependency and may be important in the subsequent morbidity associated with this group of very low birthweight infants.

Blood Pressure↗
PubMed1995

Measurement of cerebral venous oxyhemoglobin saturation in children by near-infrared spectroscopy and partial jugular venous occlusion.

Changes in cerebral venous oxyhemoglobin saturation reflect changes in the balance between cerebral oxygen delivery and cerebral oxygen consumption. Invasive monitoring of cerebral venous saturation (CSVO2) has provided useful information in the management of critically ill adults at risk of cerebral hypoxia. This study describes the development and validation of a non-invasive method of measuring CSVO2 suitable for use in sick neonates using near-infrared spectroscopy (NIRS) and partial jugular venous occlusion. This technique was validated by comparison with an invasive measurement of CSVO2, co-oximetry of jugular bulb blood obtained during cardiac catheterization. Agreement between the two methods was assessed using the method of J. M. Bland and D. G. Altman. Fifteen children were studied, aged 3 mo to 14 y (median 2 y). CSVO2 by co-oximetry ranged from 36 to 80% (median 60%). The mean difference (Co-Oximeter - NIRS) was 1.5%. Limits of agreement were -12.8 to 15.9%. Three different methods of analyzing the NIRS signal were compared. The best agreement was obtained when the changes occurring during the first 5 s of partial jugular venous occlusion were studied. Greatest accuracy was seen in those subjects with least movement artifact, and we believe this technique will be reliable in sick neonates.

Adolescent↗
PubMed1994

Neonatal intracranial lesions following placental abruption.

A case-controlled study of the cerebral ultrasound appearances of neonates following placental abruption was undertaken. Twenty-nine index subjects (median gestation 29 weeks) were identified over a 2-year period with gestation- and sex-matched controls. Placental abruption was associated with a four-fold increased incidence of periventricular leukomalacia and extensive periventricular haemorrhage, without increased mortality. Ten infants (34%) developed cystic periventricular leukomalacia following placental abruption, compared with three (10%) in the control group. Intraventricular haemorrhage (excluding subependymal haemorrhage) and haemorrhage into the brain parenchyma occurred in 21 (72%) infants in the abruption group, compared with 14 (48%) in the control group (P < 0.05).

Abruptio Placentae↗
PubMed1993

Ureaplasma urealyticum and chronic lung disease.

Neonatal lower respiratory tract colonisation with mycoplasma organisms was examined for an association with chronic lung disease. Ureaplasma urealyticum colonised 9/70 (13%) infants less than 1500 g. Seven (78%) colonised and 33 (54%) non-colonised infants developed chronic lung disease. Logistic regression analyses revealed early gestation, but not mycoplasma colonisation, was independently associated with chronic lung disease.

Chronic Disease↗
PubMed1993

The apparent role of blood transfusions in the development of retinopathy of prematurity.

During a 30-month-period, 184 very low birth weight infants from two Liverpool neonatal intensive care units were screened for evidence of retinopathy of prematurity (ROP). Seventeen clinical variables previously considered relevant to the development of ROP, blood gas and blood pressure data over the first 7 days, and the maximum stage of ROP reached in either eye were recorded, together with the need for cryotherapy and current visual status. Ninety-two infants developed any stage of ROP and 15 required cryotherapy or became blind. Logistic regression showed that only gestational age and frequency of blood transfusion were independently associated both with the risk of occurrence of ROP and its severity.

Female↗
PubMed1993

A comparison of three procedures to assess the motor ability of 12-month-old infants with cerebral palsy.

This study compared three methods of assessing motor impairment during infancy. The 77 infants studied were considered to be at high risk of motor impairment because of abnormal neonatal cranial ultrasound scans or abnormal somatosensory responses. The children were assessed at eight and 12 months post-term by the Movement Assessment of Infants, the Griffiths locomotor development quotient and the limb-by-limb approach, and the results were compared with clinical assessment at 12 months post-term. The sensitivity of the limb-by-limb approach was highest, although its specificity was slightly lower than the other tests. It was also the easiest to perform. While giving information about the quality of movement, none of these methods is a quantitative test of movement.

Cerebral Palsy↗