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Biomedical subjects

A D Rothberg

Publications and source records attributed to A D Rothberg.

At least 37 records · Page 2Linked to original sources
PubMed1995

Reasons for failure to administer antenatal corticosteroids in preterm labour.

A retrospective review of 101 preterm infants delivered at Johannesburg Hospital was conducted to determine the use of antenatal corticosteroids (ACs). Overall there were 38 opportunities for the use of ACs of which 18 were missed. Of the remaining mothers, 32 presented in advanced labour, 22 presented with obstetric emergencies and 6 were managed as inevitable abortions. There was a significant association between lack of antenatal care and presentation in advanced labour. Therefore, although only 20% of mothers received ACs, there was no opportunity for their use in the majority of patients. The use of a safe and cost-effective measure such as ACs should not be ignored in a country with limited health resources. Better antenatal care as well as increased awareness among obstetricians is required to improve the situation.

Adrenal Cortex Hormones↗
PubMed1995

Determinants of blood pressure in Sowetan infants.

A study of the effect of different variables on the blood pressure of Sowetan infants was undertaken with the Birth-to-Ten (BTT) cohort as the study population. Variables studied at 1 year included anthropometric indices, aspects of feeding practices and relationship to maternal blood pressure. Systolic blood pressure was recorded in 792 infants at 1 year; 29,3% of the variance was determined by weight, upper arm circumference, age at which formula feeds were started, length and volume of formula feeds (in order of significance). Amount of salt added to diet approached statistical significance. Data available for 353 of the 752 infants showed a correlation between the infants' and the mothers' blood pressure. The maternal blood pressure only accounted for an additional 2% of the variance; approximately 70% of blood pressure variance is therefore still unexplained. Firm recommendations with regard to use of formula feeds and the addition of salt to infants' diet are difficult to make on the basis of this limited follow-up.

Anthropometry↗
PubMed1995

Selection of paediatric patients for intensive care.

OBJECTIVES: To determine characteristics of older infants and children admitted to the paediatric intensive care unit (PICU) at Johannesburg Hospital; and to evaluate an admission score based on the PRISM score (an index of severity of illness) as a possible means for selection of patients for admission to the PICU. DESIGN: Retrospective review of patient records and calculation of admission score from data. SETTING: Paediatric intensive care unit at Johannesburg Hospital. SUBJECTS: All patients older than 3 months of age admitted to the PICU from July 1993 to 31 March 1994. RESULTS: There were 117 admissions during the study period with a mean age of 4,6 years. The mortality rate was 29.1%. The mean duration of ICU stay was 4,2 days. A review of requests for admission showed that over a 7-month period, 53 patients (> 3 months) could not be accommodated. In 71 patients with complete data, the admission score was significantly higher in non-survivors than survivors. The area under the ROC curve for predicting mortality from the admission score was 0.73 (SE 0.054). An admission score > or = 16 predicted mortality with a sensitivity of 42% and a specificity of 98%. CONCLUSIONS: PICU facilities at Johannesburg Hospital are insufficient to meet the demand. An admission score based on the PRISM score could assist in the selection of patients for these limited PICU facilities.

Adolescent↗
PubMed1994

Measurement of respiratory mechanics in a mechanically ventilated infant lung simulator: effects of variations in the frequency response of the flow measurement system.

The frequency responses of systems used to measure flow and pressure in ventilated infants may differ, and hence affect estimates of resistance and compliance. We estimated resistance and compliance in 16 ventilated mechanical lung models using linear regression while varying the frequency response of the flow measurement system. Lung models comprised combinations of four sections of tubing and four bottles filled with steel wool. The cut-off frequencies of a filter in the flow measurement system were chosen to yield time delays of 0, +/-3, +/-6, and +/-9 ms relative to the pressure signal. When the phase lags in the measurement systems were not equal at 10 Hz, a bias in resistance approximately (relative delay) x (elastance) ensued. The bias in the resistance estimate when resistance is 5 Pa ml-1 s and compliance is 2 ml kPa-1 is approximately 28% per ms of delay mismatch. Time-shifting the flow data to eliminate the phase discrepancy reduced the resistance bias by 85%. The residual resistance bias was assumed to be due to inappropriate amplitude response. Compliance measurements were affected by less than 8% and less than 2% after time correction of the flow data. Pressure and flow signals must be synchronized to within 1 ms at 10 Hz and the amplitude responses of the measurement systems must be adequate for reliable resistance measurement.

Adult↗
PubMed1994

Human B19 parvovirus infection in an obstetric population. A prospective study determining fetal outcome.

In a prospective study of 1,967 pregnant women who were routinely screened for recent human B19 parvovirus infection, 64 (3.3%) were identified as being IgM positive. No adverse effects were documented by ultrasound in any of the fetuses. The outcome of pregnancy was favorable in 95.1% of these women, with no evidence of hydrops fetalis or any congenital abnormalities. Two neonates (3.4%) were small for gestational age, and there was one abortion. Samples of blood obtained from 20 neonates born to women with evidence of recent infection were B19 parvovirus IgM negative. Recent infection with human B19 parvovirus in pregnancy constitutes a low risk for the development of adverse fetal effects; hence, routine antenatal screening is not warranted.

Antibodies, Viral↗
PubMed1994

Prevalence of hyaline membrane disease in black and white low-birth-weight infants.

Previous studies in South Africa and elsewhere have suggested that there are ethnic differences in the prevalence of hyaline membrane disease (HMD). This study compared the prevalence of HMD between black and white infants with birth weights of 1,000-1,749 g. A cohort of black and one of white low-birth-weight infants were enrolled at Baragwanath and Johannesburg Hospitals respectively. Black infants were found to have a higher rate of intra-uterine growth retardation. When compared according to either birth weight or gestational age categories, black infants had a significantly lower prevalence of HMD. For example, between 29 and 34 weeks' gestation 36.2% of black and 62.5% of white infants developed HMD (P < 0.001). The reasons for these differences are not clear, however, and require further study.

Black People↗
PubMed1993

Does hypoxemia prevent brain damage in birth asphyxia?

The clinical syndrome of hypoxic ischemic encephalopathy (HIE) which occurs in association with birth asphyxia, is thought to represent a reperfusion injury consequent upon the generation of cytotoxic oxygen derived free radicals. It has recently been suggested that resuscitation of asphyxiated infants with unrestricted oxygen may aggravate the brain damage by causing hyperoxia and increased free radical production. To determine whether sustained hypoxemia may be protective in birth asphyxiated infants, we investigated the relationship between HIE and persistent pulmonary hypertension of the neonate (PPHN). The latter condition is also related to intrauterine and intrapartum birth asphyxia but is associated with persistent hypoxemia in the infant. In a retrospective analysis of 39 asphyxiated neonates admitted to the neonatal intensive care unit, we found that 28 had HIE, 10 had PPHN and only 1 had both HIE and PPHN. We therefore suggest that the hypoxemia due to PPHN may limit the production of oxygen derived free radicals in asphyxiated neonates and hence protect against the development of HIE. These findings lend support to current research into air vs. oxygen resuscitation for infants with birth asphyxia.

Asphyxia Neonatorum↗
PubMed1993

Bandwidths of respiratory gas flow and pressure waveforms in mechanically ventilated infants.

The frequency content of airway pressure and gas flow in mechanically ventilated infants (MVIS) has not been adequately investigated. Pressure-cycled infant ventilators generate pressure pulses with short rise-times. Gas flow is approximately equal to the derivative of pressure when lung compliance is low, and hence contains high-frequency components. We defined bandwidth as that frequency fm below which 99.9% of the energy of the signal resided. Simulation of the measurement process using measurement systems with frequency response similar to sixth-order Bessel filters and a lung model comprising series resistance, inertance and compliance showed that measurement systems with frequency response flat +/- 10% to fm yield time domain errors less than 3% of the peak value. We digitized pressure and flow signals from 10-20 ventilator (Healthdyne 105) breaths in 33 stable MVIS. The transducers' (Gould P50, Hans Rudolph 8300 screen pneumotach) frequency responses had been measured between 1 Hz and 100 Hz and phase matched at 10 Hz. We calculated total respiratory resistance R and elastance E using multiple linear regression, and ensemble-average power spectral density using the FFT with a rectangular time window and padding to 2048 points. Power spectra were compensated for non-unity transducer and anti-alias filter responses up to 60 Hz. Measured data sequences that were not self-windowing due to spontaneous breathing efforts, that yielded regression R2 < 0.95 or that contained flow oscillations due to secretions in the airway were discarded. Satisfactory results were obtained from more than eight breaths in 18 infants. Mean bandwidths (+/- SD) of pressure and flow waveforms were 4.7 +/- 0.7, range 3.5-5.9 and 19.6 +/- 6.5, range 10.8-32.1 Hz, respectively. Flow bandwidths B correlated with the respiratory time constant tau (B = -77.2 tau + 26.8, R2 = 0.55, P < 0.0002), and with elastance E (B = 61.4E + 10.1, R2 = 0.74, P < 0.0001). We conclude that the bandwidth of the flow waveform increases with decreasing compliance and mechanical time constant. The frequency response of pressure and flow measurement systems should be flat +/- 10% at least up to 6 and 32 Hz respectively to obtain data with dynamic errors less than 3% in infants with low-compliance lung disease.

Humans↗
PubMed1993

Congenital syphilis as a notifiable disease.

A review of the notification of congenital syphilis at Johannesburg Hospital from 1 May 1991 to 30 April 1992 was conducted to evaluate the effect of the recently introduced notification programme. A total of 209 Wassermann reaction (WR)-positive mothers were delivered during this time; 12 pregnancies (5.7%) resulted in stillbirths and 8 (3.8%) in incomplete abortions, and there were 2 (0.96%) early neonatal deaths. Only 45 (21.5%) of this group of WR-positive mothers had received antenatal care, and of these 9 (20%) had had adequately documented treatment. There were thus 200 potentially notifiable cases of congenital syphilis according to the Centers for Disease Control classification, of which 24 (12.0%) were actually notified. The goals of the notification programme, namely to increase awareness of congenital syphilis among health care providers and to evaluate the extent of the problem accurately, are clearly not being met.

Health Personnel↗
PubMed1992

Speech and hearing problems in a high-risk population.

A retrospective study was conducted on 85 neonatal intensive care unit (NICU) survivors, all of whom had been mechanically ventilated. Mean birth weight was 1,726 +/- 778 g and mean gestational age was 32.3 +/- 3.8 weeks. Infants were evaluated for various risk factors previously reported to cause hearing loss. Language development was assessed using the Early Language Milestone (ELM) scale and hearing was tested by free field responses (FFR). Twenty-four children (28.2%) had an abnormal ELM or FFR result. Seventeen children failed an FFR; 14 of these were normal on follow-up and 3 defaulted. There was thus no permanent sensorineural hearing loss in the sample assessed. Eleven children failed an ELM, of whom 5 had speech problems on long-term follow-up. There was a significant correlation between the ELM and neurodevelopmental scores (P = 0.045). Intraventricular haemorrhage also correlated significantly with the ELM score (P = 0.0016). Thus the overall incidence of hearing loss in this NICU population was low, but there was a significant occurrence of speech problems, which correlated with neurological damage.

Female↗
PubMed1991

Non-ketotic hyperglycinaemia in a neonate. A case report.

Non-ketotic hyperglycinaemia was diagnosed in a newborn infant presenting with lethargy, apnoea, hiccoughs and myoclonic seizures. The typical findings of raised cerebrospinal fluid:plasma glycine ratio, a burst suppression pattern on electro-encephalography, hypodense areas seen on computed tomography and lack of acidosis, ketosis and serum organic acid abnormality confirmed the diagnosis. Prenatal diagnosis by investigating the glycine cleavage enzyme system from a chorionic villus sample is not yet available.

Amino Acid Metabolism, Inborn Errors↗
PubMed1991

Effect of stress on birth weight in two Johannesburg populations.

The effect of stress on birth weight was assessed in mothers delivering at Johannesburg (predominantly white) and Baragwanath (exclusively black) Hospitals. The Social Readjustment Rating Scale of Holmes and Rahe was used to assign maternal stress scores established during an interview conducted within 36 hours of delivery. Only mothers without medical problems who had delivered liveborn infants were included. Maternal age, obstetric history, smoking history and stresses present during the 12 months preceding delivery were recorded. Of 535 Johannesburg and 662 Baragwanath mothers studied, 48% and 55% respectively reported significant stresses. Analysis of the two groups revealed that for the Johannesburg mothers, smoking, cumulative stress score and previous preterm birth were important determinants of birth weight. Of the stress factors studied, marital separation and death of a spouse were significantly associated with a lower birth weight. For Baragwanath mothers the major determinants of low birth weight were maternal age, loss of income through being dismissed from work, or having to leave school as a consequence of the pregnancy.

Black or African American↗
PubMed1991

Effect of airway inertance on linear regression estimates of resistance and compliance in mechanically ventilated infants: a computer model study.

Respiratory inertance (I) is usually ignored when resistance (R) and compliance (C) of mechanically ventilated infants are estimated by least squares linear regression. Values of I that have been reported for these patients can cause impedances whose magnitudes approximate respiratory resistance. We show theoretically that if inertance is neglected no error is expected in resistance estimates, but a positive bias in compliance can be, proportional to the inertance, the compliance, and the sinusoidal frequency at which the measurements are made. To determine the errors in parameter estimates when the pressure waveform is non-sinusoidal, we simulated linear regression based on non-inertive and inertive models. R, C, and I of the simulated lung were varied over the range expected in an infant intensive care unit. The ventilator was simulated as a critically damped second order system with a square pulse input. The rise time (TR) of the pressure pulse was varied over the range reported in infant ICUs. Simulated measurements confirmed that resistance is correctly estimated if inertance is neglected. Maximum error in compliance estimates (13%) occurred when TR and R were low, and C and I were high. The variation in the error in estimated compliance was consistent with the theory. Coefficients of variation of the parameters, the standard errors, and R2 of the regressions tended to deteriorate with increasing compliance error, but the relationships were not single valued. These statistics may alert investigators to possible bias in compliance caused by neglected inertance, but cannot be used to correct any bias.

Airway Resistance↗