Search PubMed⌕ Search

Biomedical subjects

S Abbasi

Publications and source records attributed to S Abbasi.

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

The HA1 of cold-adapted influenza B vaccine is not altered during replication in human vaccinees.

Influenza viruses recovered from 14 children 2-10 days after vaccination with an egg-grown, cold-adapted influenza B vaccine (B/AA/1/86) were analyzed. Hemagglutination-inhibition (HI) assays using monoclonal antibodies did not detect antigenic differences between the vaccine strain and the viruses recovered from the vaccinees. Furthermore, nucleotide sequence analysis of the HA1 region did not reveal any changes compared to the sequence of the vaccine strain. These findings indicate that influenza B vaccine hemagglutinin is genetically stable during replication in human vaccinees.

Animals↗
PubMed1995

Penicillin- and cephalosporin-resistant strains of Streptococcus pneumoniae causing sepsis and meningitis in children with sickle cell disease.

OBJECTIVE: We investigated the possibility that antimicrobial-resistant pneumococci were causing invasive disease in children with sickle-cell disease (SCD). STUDY DESIGN: Records of all children with SCD observed at the Mid-South Sickle Cell Center (MSSCC) at LeBonheur Children's Medical Center were reviewed from January 1990 to June 1994. Children with SCD and pneumococcal sepsis were identified. The Streptococcus pneumoniae isolates from these children were examined for serotype and antimicrobial susceptibilities. Two additional children not observed in the MSSCC had pneumococcal sepsis caused by penicillin-resistant isolates and were also included. RESULTS: Antimicrobial susceptibility testing of the six penicillin-resistant isolates revealed that four were resistant to trimethoprim-sulfamethoxazole, two to erythromycin, and one to clindamycin. The two isolates that were resistant to ceftriaxone also were multiply resistant. From the MSSCC, 26 children had pneumococcal sepsis during the 4 1/2-year period studied. Five of these children (19%) died. Four (15%), including one who died, were infected with penicillin-resistant strains. CONCLUSION: Pneumococcal sepsis, meningitis, and infections of other foci in children with SCD may be caused by S. pneumoniae that is resistant to one or more antimicrobial agents, including penicillin. The addition of vancomycin to the antibiotics currently used for initial management should be considered in areas where the antibiotic resistance of S. pneumoniae is prevalent.

Anemia, Sickle Cell↗
PubMed1995

Severe retinopathy of prematurity in infants with birth weights less than 1250 grams: incidence and outcome of treatment with pharmacologic serum levels of vitamin E in addition to cryotherapy from 1985 to 1991.

OBJECTIVE: To determine the effect of vitamin E prophylaxis and treatment on the sequelae of severe (threshold) retinopathy of prematurity (ROP) in infants treated with cryotherapy at Pennsylvania Hospital from 1985 to 1991. STUDY DESIGN: Beginning on day 0, all infants with birth weights < or = 1250 gm received supplements of vitamin E using standard preparations. Serum E levels of 23 to 58 mumol/L (1 to 2.5 mg/dl) were targeted for infants with immature retinal vasculature or ROP of stage 2 or less in severity, and levels of 58 to 81 mumol/L (2.5 to 3.5 mg/dl) for infants with prethreshold ROP. At diagnosis of threshold ROP, treatment with a parenteral investigational new drug preparation of alpha-tocopherol was begun to raise serum levels to the pharmacologic range (93 to 116 mumol/L or 4 to 5 mg/dl). Within 3 days of diagnosis, and at the discretion of the retinal specialist, one or both eyes were treated with cryotherapy. Visual outcome at 4 years was compared with the 42-month outcome reported for eyes in the infants randomly assigned to treatment in the 1986-1987 Multicenter Trial of Cryotherapy for ROP (CRYO-ROP). RESULTS: Threshold ROP developed in 22 of 450 surviving infants (age 3 months). All were treated with pharmacologic serum levels of vitamin E; 17 infants were also treated with cryotherapy (10 in one eye and 7 in both eyes). These 17 infants, in comparison with infants in the CRYO-ROP trial (n = 187), were at least at equal risk for poor visual outcome on the basis of birth weight, gestational age, the percentage of zone 1 ROP, and mean interval from appearance of ROP to diagnosis of prethreshold ROP, which was shorter at Pennsylvania Hospital (4.1 days for the Pennsylvania Hospital group, 10.3 days for the CRYO-ROP group). However, on the basis of the mean number of days from diagnosis of prethreshold to threshold ROP (12.5 days for Pennsylvania Hospital, 10.5 days for CRYO-ROP) and the extent of extraretinal neovascularization at threshold (mean 7.9 sectors for Pennsylvania Hospital, 9.7 for CRYO-ROP), progression of retinopathy beyond the prethreshold stage had slowed and visual outcome in the eyes of infants at Pennsylvania Hospital treated with both cryotherapy and vitamin E (worse eye used for those treated with bilateral cryotherapy) was better than that reported for the treated eye of infants in the CRYO-ROP group (percentage of favorable visual acuity, 76% vs 48%, p = 0.04; percentage of normal structure posterior retinal pole, 71% vs 38%, p < or = 0.02). CONCLUSIONS: In this small case series, the combination of cryotherapy with anti-oxidant prophylaxis and treatment appeared to decrease the severity and sequelae of threshold ROP. This hypothesis deserves testing in a large, randomized clinical trial.

Combined Modality Therapy↗
PubMed1994

Influence of head-neck posture on airflow and pulmonary mechanics in preterm neonates.

The influence of head-neck posture (neutral, 15 degrees, 30 degrees, and 45 degrees extension and flexion) on airflow and pulmonary mechanics was evaluated in 10 spontaneously breathing healthy preterm neonates (mean +/- SD; birth weight, 1.32 +/- 0.23 kg; gestational age, 29.4 +/- 2.4 weeks; study age, 36.6 +/- 1.6 weeks) who had had respiratory distress syndrome. Head-neck postures were quantified using specially constructed wooden wedges. Airflow was measured by a pneumotachometer via face mask. Lung compliance (CL) and resistance (RL) were measured using an esophageal balloon. Airflow interruption was designated as mild (10-40%), moderate (40-80%), and severe (> 80-100%) decrease of airflow. At neutral head-neck posture, 42.8 +/- 7.5% SEM of breaths had airflow interruption (71.4% mild, 19.9% moderate, 8.7% severe). There was no significant change with 15 degrees and 30 degrees head-neck flexion and extension. However, at 45 degrees flexion the overall incidence of airflow interruption (77.3 +/- 4.8%, P < 0.05) and RL (86.6 +/- 6.7 vs. 64.2 +/- 3.9 cmH2O/L/s, mean +/- SEM; P < 0.05) significantly increased. Extension to 45 degrees caused severe airflow interruption and increased RL in some infants, but no statistically significant change for the whole group. The incidence of severe airflow interruption significantly increased (P < 0.05) from 8.7% at neutral head-neck posture to 26.3% at hyperflexion (45 degrees). No changes in CL were observed. We conclude that minor (15-30 degrees) deviations from neutral neck posture are insignificant, whereas hyperflexion, and in some infants, hyperextension, can significantly affect airflow and pulmonary mechanics.

Airway Resistance↗
PubMed1994

Role of positive end-expiratory pressure changes on functional residual capacity in surfactant treated preterm infants.

Both surfactant replacement and positive end-expiratory pressure (PEEP) increase lung volume in infants with respiratory distress syndrome (RDS). We measured pulmonary mechanics and functional residual capacity (FRC) in 21 preterm infants with RDS, > 48 hr post-surfactant therapy (BW, 1,168 +/- 441 g; GA, 28.3 +/- 2.8 weeks; postnatal age, 3-7 days). A non-linear but significant increase in mean FRC was noted as PEEP increased from 2 to 5 cmH2O: 18.4 +/- 4.7 mL/kg at 2 cmH2O; 19.7 +/- 4.3 mL at 3 cmH2O; 22.6 +/- 5.5 ml/kg at 4 cmH2O; and 26.2 +/- 6.2 mL/kg at 5 cmH2O (P < 0.01). Because of the synergistic combined effect on lung volume, surfactant treated neonates should be weaned cautiously from PEEP during ventilatory management. Our study also suggests that the occurrence of inadvertent end-distending pressure during FRC measurement in the ventilated neonate lead to erroneous results.

Female↗
PubMed1994

Gastrointestinal and renal blood flow velocity profile in neonates with birth asphyxia.

Pulsed Doppler ultrasound blood flow profiles were studied, before the initiation of enteral feedings, in 23 neonates with birth asphyxia. We observed a significant direct correlation between the reduction of peak velocity and increased resistance in the renal and superior mesenteric arteries to the severity of asphyxia (r = 0.8; p < 0.05); the changes often persisted up to 3 days of age. Longitudinal evaluation of flow in these vessels might help to time the initiation of enteral nutrition in neonates with asphyxia.

Asphyxia Neonatorum↗
PubMed1993

Evaluation of pulmonary functions during pressure-limited manual ventilation in preterm neonates.

Manual ventilation (MAV) or handbagging is a frequent and often life-saving procedure for neonates; however, few studies allow for an objective evaluation of techniques or possible risks. We compared parameters of ventilation and pulmonary mechanics obtained during routine pressure-limited MAV to those obtained during spontaneous breathing (SPB) in the same infant at approximately the same time. We selected 20 preterm neonates in the recovery phase of respiratory distress syndrome who received periodic MAV and were capable of optimum spontaneous minute ventilation (> 300 mL/kg/min). During MAV compared to SPB we measured higher tidal volume (8.1 +/- 0.5 SE vs. 5.4 +/- 0.4 SE mL/kg, P < 0.001), lower total pulmonary compliance (0.65 +/- 0.05 vs. 1.16 +/- 0.11 SE mL/cmH2O, P < 0.001), end-inspiratory compliance, higher pulmonary resistance (121 +/- 11 vs. 61 +/- 7 SE cmH2O/L/s, P < 0.001) and higher peak inspiratory airflow (2.8 +/- 0.2 vs. 1.6 +/- 0.1 L/s, P < 0.001). Inspiratory time (Ti) was consistently longer during MAV (0.49 +/- 0.02 vs. 0.36 +/- 0.02 SE, P < 0.001) such that during MAV the difference between actual Ti and minimal effective Ti (fivefold inspiratory time constant) was larger (0.29 +/- 0.03 vs. 0.13 +/- 0.03 s, P < 0.05). Our study suggests that operator-dependent ventilatory variables such as tidal volume, inspiratory time, frequency, and airflow need to be further evaluated in order to develop standardized guidelines for the safe administration of MAV. Until then the ventilator used for brief or augmented ventilatory support is a reasonable alternative to administering MAV by inconsistent standards.

Humans↗
PubMed1993

Long-term pulmonary consequences of respiratory distress syndrome in preterm infants treated with exogenous surfactant.

The pulmonary outcome for preterm infants 1 year after synthetic surfactant replacement for respiratory distress syndrome was assessed by examining their pulmonary status and the results of pulmonary function tests. A total of 47 infants were followed: 13 infants mean +/- SD: birth weight, 1960 +/- 616 gm; gestation, 32 +/- 1.1 weeks) had been assigned to the placebo group and 34 (birth weight = 1890 +/- 530 gm; gestation = 32 +/- 2.5 weeks) to surfactant treatment. The infants were examined at 3 to 6 months of age (n = 45) and at 9 to 12 months of age (n = 36). There were no significant differences between the two groups in predisposing clinical conditions that would lead to chronic lung disease. The infants had similar patterns of growth, respiratory-related illness, and need for theophylline therapy, diuretic therapy, or both. None had hypoxemia by pulse oximetry. Mean (+/- SEM) values for pulmonary mechanics and energetics in surfactant-treated infants were significantly (p < 0.01) lower for total pulmonary resistance in late infancy (57.7 +/- 11.7 vs 35.3 +/- 4.6 cm H2O/L per second). Lower values (mean +/- SEM) of resistive work of breathing were also measured in the surfactant-treated group (60.7 +/- 12.0 vs 38.2 +/- 3.6 gm-cm/kg per breath). The dynamic pulmonary compliance values were in the low-normal range for both groups, and the mean (+/- SEM) peak-to-peak esophageal pressure values were elevated (11.47 +/- 2.26 cm H2O in the placebo group; 9.24 +/- 0.69 cm H2O in the surfactant group). Forced expiratory flow measurements in late infancy demonstrated significant (p < 0.01) improvement in expiratory reserves and reduced evidence of airflow obstruction in the surfactant-treated infants (peak flow (mean +/- SEM): 287.1 +/- 69 vs 396.9 +/- 27 ml/sec; forced expiratory flow (mean +/- SEM) at functional residual capacity: 56.3 +/- 7.5 vs 83.4 +/- 19.5 ml/sec). No significant differences in pulmonary functions were noted in early infancy. These data suggest that surfactant replacement for respiratory distress syndrome may be associated with beneficial long-term effects on the resistive airflow properties of larger preterm infants.

Drug Combinations↗
PubMed1993

Effect of enteral gavage feeding rate on pulmonary functions of very low birth weight infants.

To compare the effects of intermittent and continuous feedings on pulmonary function, we studied 24 very low birth weight neonates (mean +/- SD: birth weight, 1.2 +/- 0.3 kg; gestational age, 30.5 +/- 1.1 weeks) at 2 to 4 weeks of age. All infants had a previous diagnosis of respiratory distress syndrome but no subsequent diagnosis of bronchopulmonary dysplasia. Pulmonary mechanics were measured before the beginning of intermittent or continuous feedings and 10 minutes after each meal was completed. Twelve infants were randomly assigned to intermittent and 12 to continuous feedings. These infants had similar birth weight, gestational age, study age, and baseline lung function. After intermittent feedings, there was a significant decrease in tidal volume (38%), minute ventilation (44%), and dynamic compliance (28%), whereas pulmonary resistance increased significantly (100%). In comparison, the pulmonary function data remained unchanged after continuous feedings. These data demonstrate that intermittent feeding of very low birth weight infants can lead to airflow and respiratory instability. These adverse effects appear to be dependent on the rate that feedings are administered. A slower pace of feeding may be more advantageous for infants prone to respiratory instability.

Enteral Nutrition↗
PubMed1992

Alpha-adrenergic bronchoprovocation in neonates with bronchopulmonary dysplasia.

Ophthalmic administration of phenylephrine caused decreased pulmonary compliance, tidal volume, and peak airflow values in infants with bronchopulmonary dysplasia but not in control infants. The alpha-adrenergic effects of phenylephrine may aggravate the bronchospastic component of bronchopulmonary dysplasia.

Bronchial Hyperreactivity↗
PubMed1992

Pulmonary mechanics and energetics in preterm infants who had respiratory distress syndrome treated with synthetic surfactant.

Pulmonary mechanics and energetics were determined in 32 neonates with respiratory distress syndrome, who were randomly assigned to receive treatment with an exogenous synthetic surfactant, Exosurf Neonatal, or air placebo. Pulmonary mechanics were measured before and 2 hours after surfactant (n = 13) or air placebo (n = 19) treatment, then longitudinally at 24, 48, and 72 hours after treatment, and again at 7, 14, and 28 days of age. There were no significant differences in the values for pulmonary mechanics or energetics 2 hours after the first dose of surfactant. Improvement in pulmonary mechanics was apparent 24 hours after surfactant treatment, when dynamic compliance was 36% greater than in the placebo group (p less than 0.03). Lung compliance values were also higher in surfactant-treated infants 48 and 72 hours after treatment, with a maximal increase of 64% at 7 days of age (p less than 0.03). Surfactant treatment also caused a significant decrease in total pulmonary resistance at 48 and 72 hours after initial treatment and at 14 days of age (p less than 0.04). Similarly, a decrease in flow-resistive work of breathing was demonstrated 24, 48, and 72 hours after surfactant treatment. At 28 days of age, pulmonary mechanics were not different in the two groups. We conclude that beneficial effects of surfactant on pulmonary mechanics were not apparent 2 hours after dosing but were evident 24 hours after dosing and persisted for the first 7 to 14 days of life.

Drug Combinations↗
PubMed1992

Relative likelihood of bronchopulmonary dysplasia based on pulmonary mechanics measured in preterm neonates during the first week of life.

We studied 143 low birth weight infants (less than or equal to 1500 gm) with respiratory distress syndrome who required mechanical ventilation, and determined the efficacy of using the alterations in pulmonary mechanics (measured at 1 to 3 days, 4 to 7 days, 2 weeks, and 4 weeks) as possible predictors for the subsequent diagnosis of bronchopulmonary dysplasia (BPD). The sensitivity and specificity of pulmonary compliance and resistance as predictors of BPD were ascertained by logistic regression correlation (p less than 0.01) and receiver operating characteristic curves. With these pulmonary mechanics data and logistic discriminant analysis techniques, we developed BPD prediction models based on pulmonary mechanics, measured between 4 and 7 days of age, to define the likelihood ratio for the subsequent diagnosis of BPD. Eight different BPD prediction models were developed by using combinations of four vectors (pulmonary compliance, total pulmonary resistance, birth weight, gestational age), and each model was validated in a subsequent low birth weight study population (n = 53). All models were deemed accurate for negative prediction of BPD. The models dependent on gestational age and dynamic pulmonary compliance had the highest positive predictive accuracy. The predictive impact of total pulmonary resistance appeared to be minimal. These prediction models may be used to calculate the likelihood ratio for a subsequent BPD diagnosis and thereby objectively categorize both the risk and the magnitude of acute lung injury by the first week of life.

Airway Resistance↗
PubMed1992

Onset of retinopathy of prematurity as related to postnatal and postconceptional age.

The hypothesis that both perinatal events and stage of retinal development are important factors in determining the age at onset of retinopathy of prematurity (ROP) was tested by comparing gestational age at birth with postnatal and postconceptional age when ROP (using ICROP) was first seen. The study population consisted of 207 infants (111 placebo (P) treated, 96 vitamin E (E) treated) who developed ROP among a group of 914 premature infants (460 P, 454 E) enrolled in a randomised clinical trial of the effect of prophylactic use of vitamin E at pharmacological serum levels on incidence and severity of retinopathy. The mean postnatal age at onset of retinopathy was delayed in E treated infants compared with P treated infants by 1.4 weeks (t = 4.004, p < 0.0001). For both P and E treated infants postnatal age at onset of ROP (which reflects the state of retinal development at which birth insults occur) and postconceptional age at onset of ROP which defines state of maturity) were correlated with gestational age at birth. This suggests that both the event of premature birth and the extent of retinal development are important in determining when ROP will first be observed.

Aging↗
PubMed1992

Long-term pulmonary consequences in survivors with bronchopulmonary dysplasia.

The clinical and pulmonary function test evidence of abnormal airway function in infants with BPD is now well established. Studies have shown persistence of airway obstruction into childhood and evidence of residual dysfunction into adulthood. Furthermore, preterm neonates who have been mechanically ventilated but do not meet any of the BPD definitions also have residual pulmonary dysfunction during infancy. As an increasing number of very low birth weight infants survive in the surfactant era, care must be taken to note that their airways are likely to be extremely compliant and thereby exceedingly susceptible to airway barotrauma in the neonatal period. The long-term consequences of airway injury could lead to residual abnormal airway function during infancy. It is hoped that barotrauma can be minimized substantially with a reduction in both the magnitude and duration of ventilatory support following surfactant therapy. With the advent of user-friendly commercial pulmonary function testing equipment, most neonatal follow-up services should include a comprehensive pulmonary follow-up ancillary to the existing neurodevelopmental follow-up services and may thereby reduce the severity of respiratory morbidities and the need for hospital readmissions.

Adrenal Cortex Hormones↗
PubMed1991

Closure of the ductus arteriosus with indomethacin in ventilated neonates with respiratory distress syndrome. Effects of pulmonary compliance and ventilation.

The reported effects of indomethacin on pulmonary compliance are variable depending upon the patient population and on the degree to which indomethacin resulted in successful ductal closure. Eleven fluid-restricted, furosemide-treated premature infants being mechanically ventilated for respiratory distress syndrome (RDS) who also had a significant patent ductus arteriosus (PDA) had pulmonary function testing performed before and after successful closure of the PDA. The diagnosis of a significant PDA was made by clinical and echocardiographic criteria. Indomethacin was administered at a dosage of 0.2 mg/kg/dose every 12 to 18 h for 1 to 3 doses. To control for the 48-h time interval to achieve ductal closure, nine premature infants being ventilated for RDS but who did not have a significant PDA also had pulmonary function evaluations performed before and after the 48 h. Also, to control for the independent effect of fluid restriction and diuretic therapy on pulmonary compliance, eight such premature infants with a PDA had pulmonary function evaluations performed at a 48-h interval. Successful closure of the ductus with indomethacin was associated with an improvement in compliance and ventilation parameters in all infants in the indomethacin-treated infants. In the indomethacin-treated group, the mean percent improvements were noted in the following parameters: CLdyn, 59.2%; CLI, 78.3%; CLE, 63.3%; VT, 63.3%; VE, 54.6%. There were no significant changes in the pulmonary functions in the 48-h RDS or the 48-h PDA fluid-restricted, furosemide-treated control groups. In conclusion, successful closure of the ductus with indomethacin causes a significant improvement in compliance and ventilation parameters in infants being mechanically ventilated for RDS.

Ductus Arteriosus, Patent↗
PubMed1991

Pulmonary mechanics in preterm neonates with respiratory failure treated with high-frequency oscillatory ventilation compared with conventional mechanical ventilation.

Pulmonary mechanics were measured in 43 preterm neonates (mean +/- SD values of birth weight 1.2 +/- 0.3 kg, gestational age 30 +/- 2 weeks) with respiratory failure who were concurrently randomly assigned to receive conventional mechanical ventilation (n = 22) or high-frequency ventilation (n = 21). The incidence of bronchopulmonary dysplasia was comparable in the two groups (high-frequency ventilation 57%, conventional ventilation 50%). Pulmonary functions were determined at 0.5, 1.0, 2.0, and 4.0 weeks postnatal ages. Data were collected while subjects were in a nonsedated state during spontaneous breathing. These sequential data show similar patterns of change in pulmonary mechanics during high-frequency ventilation and conventional mechanical ventilation irrespective of gestational age, birth weight stratification, or bronchopulmonary dysplasia. There was no significant difference in the pulmonary functions with either mode of ventilation during the acute phase (less than or equal to 4 weeks) of respiratory disease. When evaluated by the clinical diagnosis of bronchopulmonary dysplasia, the pulmonary data suggested a less severe dysfunction in the high-frequency oscillatory ventilation-treated bronchopulmonary dysplasia group compared with the conventional mechanical ventilation-treated group. These results indicate that high-frequency oscillatory ventilation in preterm neonates does not reduce the risk of acute lung injury; however, the magnitude of the pulmonary dysfunction in the first 2 weeks of life merits a reevaluation.

Bronchopulmonary Dysplasia↗