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Biomedical subjects

R P Rivers

Publications and source records attributed to R P Rivers.

At least 37 records · Page 2Linked to original sources
PubMed1988

Ontogeny of fasting small intestinal motor activity in the human infant.

A clearly defined progression of fasting small intestinal motor development is seen in the human infant from disorganised low amplitude motor activity before 31 weeks gestation through an intermediate phase of increasing motor organisation and amplitude to the development of a normal cyclical pattern of motor activity with clearly defined phase I, II, and III activity between 37 weeks gestation and term. With increasing maturity smooth muscle contractility [gastric antral pressure (5-30 mmHg), average duodenal pressure (2-12 mmHg)], propagation and slow wave frequency (10.5-12.5 cpm) all increased in a significant fashion (p less than 0.01). The stage of development of fasting motor activity in the small intestine of the preterm infant can now be readily predicted from the gestational age of the infant.

England↗
PubMed1988

Quantification of cardiovascular instability in premature infants using spectral analysis of waveforms.

Spectral analysis was applied to blood pressure and cerebral blood flow velocity recordings in premature infants with respiratory distress in order to quantify respiration-induced cardiovascular variability. Aortic blood pressure was transduced via an umbilical arterial catheter and cerebral blood flow velocity measured in the anterior cerebral artery using a 10 MHz continuous wave Doppler velocimeter in 16 infants less than or equal to 32 wk gestational age. Spectral analysis of the resulting waveforms revealed heart rate and respiratory rate components whose relative amplitudes (heart rate/respiratory rate amplitude ratio) represent an index of that component of variability induced by respiratory events. The mean (heart rate/respiratory rate amplitude) ratio was 47.2 in spontaneously breathing infants and rose to 165.9 in infants who were ventilated during muscle paralysis (p = 0.0003). Cerebral blood flow velocity recordings showed R components in only 22 of 38 simultaneous recordings. This method can be used to quantify respiration-induced cardiovascular variability and its response to therapy, and may provide a means of identifying infants at risk from brain injury due to an inability to regulate cerebral blood flow.

Blood Flow Velocity↗
PubMed1987

Neonatal candida septicaemia: diagnosis on buffy smear.

We report a case of neonatal candida septicaemia diagnosed by examination of a buffy smear. This would seem to be a fairly simple test for a disease where a good prognosis is dependent on rapid diagnosis and isolation using standard culture techniques is notoriously unforthcoming.

Antifungal Agents↗
PubMed1987

Pulse oximeter and transcutaneous arterial oxygen measurements in neonatal and paediatric intensive care.

Pulse oximeter (SaO2P) measurements were compared with direct arterial line oxygen saturation (SaO2) from co-oximeters in 92 instances in 43 patients, and with arterial line oxygen measurements (PaO2) in 169 instances in 81 patients. The mean (SD) absolute difference between SaO2P and SaO2 was 2.6% (2.4) after attempt to correct for the co-oximeter falsely measuring a proportion of fetal haemoglobin as carboxy haemoglobin. For 19 infants and children greater than or equal to 5 months old, who have very little fetal haemoglobin, the mean (SD) absolute difference of 27 comparisons was 1.8% (2.1). Comparison of SaO2P and PaO2 measurements in 46 instances when PaO2 was less than 6.67 kPa showed SaO2 to be less than 90% on 40 occasions. In 24 instances when PaO2 was greater than or equal to 13.3 kPa the SaO2P was greater than or equal to 98% on 22 occasions. In 23 infants undergoing neonatal intensive care, transcutaneous oxygen monitors were compared with arterial PO2 measurements in 60 instances. The mean (SD) absolute difference between PaO2 and transcutaneous oxygen measurements was 1.60 kPa (1.73). Ten of the 60 comparisons had differences greater than 2.67 kPa and three greater than 5.33 kPa (maximum 8.40 kPa). Pulse oximetry is a clinically useful technique for managing oxygenation but further studies are needed to confirm its safety in premature infants at risk of retinopathy of prematurity.

Adolescent↗
PubMed1986

Group B streptococcal colonisation and the outcome of pregnancy.

Vaginal colonisation of pregnant women with group B streptococci (GBS) was not related to age, parity or blood group. There were marked differences between racial groups, Asians having a low colonisation rate and Negroes a high rate. Vaginal GBS colonisation was associated with intrapartum pyrexia, but not with preterm labour, premature rupture of membranes or other complications in labour. Group B streptococci may be an important cause of bacteriuria in pregnancy and their effect on the outcome of pregnancy as urinary pathogens needs further evaluation.

Abortion, Spontaneous↗
PubMed1985

Is group B streptococcal screening during pregnancy justified?

Twenty-eight per cent of women investigated during pregnancy were carriers of group B streptococci (GBS). The use of broth enrichment was the most significant factor in determining GBS carriage rates. GBS carriage decreased during pregnancy. Transmission of GBS from mother to baby was related to vaginal carriage but rectal carriage in pregnancy was the best predictor of maternal carriage at term. Rectal and vaginal swabs taken at 28 and 36 weeks correctly predicted 92% of intrapartum GBS carriage. Although accurate prediction of intrapartum GBS carriage is possible, mass screening for GBS in pregnancy is unlikely to be cost-effective in those countries with a low incidence of neonatal GBS sepsis.

Carrier State↗
PubMed1983

Epidemiology of group B streptococci: one year's experience in an obstetric and special care baby unit.

The epidemiology of group B streptococci (GBS) was studied in an obstetric unit and the related special care baby unit (SCBU). In 1 year 53 (77%) of 69 babies who acquired GBS from their mothers were colonized within 24 h of birth, compared with only 9 (35%) of 38 who acquired GBS from non-maternal sources. While 38 (36%) of 107 GBS colonized babies in the obstetric unit derived the organism from a non-maternal source, the value for the SCBU was only 2 (9%) of 23. In babies rectal and umbilical swabs gave the highest GBS isolation rates. Phage-typing and serotyping suggested that colonized mother baby pairs, rather than staff, were the primary source of hospital acquired GBS. This mode of GBS acquisition did not result in long-term carriage once babies had left hospital. Nosocomial transmission can play an important part in GBS epidemiology, but can be minimized by attention to infection control procedures.

Carrier State↗
PubMed1983

The effect of intrapartum chemoprophylaxis on the vertical transmission of group B streptococci.

Intrapartum chemoprophylaxis with benzylpenicillin or erythromycin significantly reduced the rate of transmission of group B streptococci (GBS) from mothers colonized during pregnancy to their babies from 45% to 3% (P less than 0.001). None of the babies born to women who were given prophylaxis was colonized with GBS in the first 24 h of life. Six weeks after leaving hospital, however, 23% of the babies in the antibiotic group had become colonized with GBS compared with 44% in the control group. GBS strains resistant and tolerant to both benzyl-penicillin and erythromycin were found in this study. Intrapartum chemoprophylaxis breaks the cycle of GBS transmission at birth and may be useful in preventing early onset GBS disease, but is unlikely to affect late onset infections.

Erythromycin↗
PubMed1983

Desquamative interstitial pneumonia and antigen-antibody complexes in two infants with congenital rubella.

Desquamative interstitial pneumonia was observed in two infants with the late-onset congenital rubella syndrome. In both infants this unusual lung disease was associated with circulating immunoglobulin M complexes and interstitial pulmonary deposits of IgM by immunofluorescence. Both infants had IgG deficiency. The first child recovered with a reduction in IgM complex levels and synthesis of rubella-specific IgG. The second infant died during the acute phase of his illness at which time there were high serum concentrations of IgM complexes and slightly increased levels of IgG complexes. Delayed maturation of the immune response in congenital rubella may predispose to persistent antigenemia and pulmonary deposition of rubella antigen-containing IgM complexes resulting in an acute form of interstitial pneumonia.

Antigen-Antibody Complex↗
PubMed1981

Nosocomial transmission of group B streptococci.

The acquisition of group B streptococci by babies in a special-care baby unit and two postnatal wards was investigated over a six-month period using serology and phage typing. Sixty-three culture-positive babies were identified in the postnatal wards, one-third of whom had been born to mothers who were not carrying the organism in the genital tract or anorectal area during labour. A non-maternal source was identified for 14 of these 21 infants: either colonised mothers and babies in the same ward or, on one occasion, a member of the hospital staff. In the special-care baby unit, however, only one instance of nosocomial acquisition of group B streptococci was recorded despite a high prevalence of colonisation in the staff on the unit and the presence of heavily colonised babies. The results of this survey suggest that although sepsis caused by group B streptococci may be the result of nosocomial transmission, this may be prevented by careful attention to hygiene.

Cross Infection↗
PubMed1977

Necrotizing enterocolitis. Controlled study of 3 years' experience in a neonatal intensive care unit.

During the 3 years 1972-74, 17 infants were treated for necrotizing enterocolitis (NEC) in the Neonatal Unit at University College Hospital. The incidence of the illness was 0.2% of live births in the hospital and 2.7% of those referred from elsewhere. The mean birthweight of the affected infants was 1832 g (range 878-3850 g) and mean gestational age 33 weeks (range 28-40 weeks). The illness was diagnosed at a mean age of 16 days (range 3-33 days). 14 infants (82%) survived. One infant developed NEC because of a volvulus, and another because of an apparently abnormal arterial supply to a segment of bowel. Each of the remaining 15 infants was matched with 3 control infants in order to see whether any factors predisposing to the development of NEC could be identified. Birth asphysia, the use of umbilical catheters, the length of time that these catheters were in place, and complications of catheterization were all significantly more frequent in the infants who developed NEC than in the controls. These findings support the view that hypoxia and ischaemia of the gut wall are important in the pathogenesis of NEC.

Birth Weight↗