Biomedical subjects

S Abbasi

Publications and source records attributed to S Abbasi.

62 records · Page 4Linked to original sources

PubMed1985

Preterm infants: ventilation and P100 changes with CO2 and inspiratory resistive loading.

The ventilatory effects of inspiratory flow-resistive loading and increased chemical drive were measured in ten neonates during progressive hypercapnia in control and loaded states. Hypercapnia (mean increase PCO2 = 15-20) resulted from inspiring 8% CO2 in room air and inspiratory loading by a flow-resistive load = 100 cmH2O X l-1) X s. Hypercapnia produced an increase in group minute ventilation secondary to increasing tidal volumes and breathing frequencies. Loading shifted the minute ventilation-CO2 response to the right, and slopes decreased significantly (P less than 0.05) consequent to a significant decrease in the frequency-CO2 slopes (P less than 0.05), which became negative in four of the ten subjects. Mouth pressure measured at 100 ms after onset of inspiratory effort (P100) occlusion pressure-CO2 slopes measured in five subjects showed no significant increase with load application. Resistive loading produced significant increases in inspiratory time (P less than 0.02) and the inspiratory time/total breath time ratio (P less than 0.01). Airway occlusion elicited the Hering-Breuer reflex, with a significant increase in inspiratory time-to-total breath time ratio (P less than 0.01). The results show that the inspiratory resistive load produced ventilatory compromise in newborns and insufficient compensatory augmentation of central drive.

Airway Resistance↗

PubMed1985

Relationship of prolonged pharmacologic serum levels of vitamin E to incidence of sepsis and necrotizing enterocolitis in infants with birth weight 1,500 grams or less.

The incidence of culture-proven neonatal sepsis and necrotizing enterocolitis (NEC) in preterm infants maintained at pharmacologic (mean 5.1 mg/dL +/- 1.45 SD) serum vitamin E levels for long periods was prospectively studied as part of a double-masked clinical trial of the effect of prophylactic vitamin E v placebo treatment on the development and course of retinopathy of prematurity (ROP). Within a few days of birth, 914 preterm infants were enrolled in the study; 545 (275 placebo-treated infants, 270 vitamin E-treated infants had birth weight of 1,500 g or less. A significant difference in incidence of neonatal sepsis (17 placebo-treated infants, 37 vitamin E-treated infants) and NEC (18 placebo-treated infants, 32 vitamin E-treated infants) was observed among infants who had been treated for eight or more days and who had developed neither sepsis nor NEC before that time. The association of vitamin E treatment with increased incidence of disease was much higher with sepsis than with NEC. The most likely reason for these observations is a pharmacologic serum vitamin E-related decrease in oxygen-dependent intracellular killing ability which results in a decreased resistance to infection in preterm infants. The data suggest that, if this occurs, it is clinically significant only in the more immature infants. In view of the known variability of absorption of oral vitamin E and the association between high serum vitamin E levels and increased incidence of sepsis and late-onset NEC reported here, it can be concluded that serum vitamin E levels must be monitored when supplemental vitamin E is administered to premature infants, especially those with birth weight 1,500 g or less. The risk-benefit ratio of long-term treatment using vitamin E at high serum levels should be clearly assessed.

Administration, Oral↗

PubMed1984

Long-term assessment of growth, nutritional status, and gastrointestinal function in survivors of necrotizing enterocolitis.

The long-term effect of necrotizing enterocolitis on growth, nutritional status, and gastrointestinal function was assessed in premature infants at the age of 1 year. Of the 22 of 40 infants who developed NEC, 18 were given medical treatment and four required surgical treatment consisting of intestinal resection of less than one fourth of the small bowel. Eighteen infants who did not develop NEC served as controls. At 1 year follow-up, NEC survivors and controls had normal and comparable anthropometric measurements, biochemical values (serum iron, albumin, prealbumin, retinol binding protein, liver function studies) and gastrointestinal tract function (vitamin E absorption, fasting serum bile acids concentration, lactose breath test). This study demonstrates that, in the absence of short bowel syndrome, there is no detectable long-term effect on growth, nutritional status, and gastrointestinal tract function in premature infants who had NEC in the newborn period.

Anthropometry↗

PubMed1984

Effect of external inspiratory loading on ventilation of premature infants.

The ventilatory response of 11 growing premature infants to external inspiratory resistive loads was evaluated. Air flow, tidal volume, minute ventilation, inspiratory duration and total breath duration were measured before and after application of a flow resistive load. A significant (P less than 0.001) immediate decrease in minute ventilation and tidal volume was observed in all infants after load application. Minute ventilation and tidal volume remained decreased throughout the 10-min study period. Minute ventilation and tidal volume for the group decreased to 48 and 50% of control mean value, respectively. In addition, there was a significant (P less than 0.001) sustained increase in inspiratory time resulting in an increase in the ratio of inspiratory time/total respiratory time.

Airway Obstruction↗

PubMedDate not supplied

Physiologic effects of terbutaline on pulmonary function of infants with bronchopulmonary dysplasia.

This study defines the physiologic changes in pulmonary mechanics induced by subcutaneous terbutaline administration in ventilator-dependent infants with severe bronchopulmonary dysplasia (BPD). Eight such infants (mean +/- SEM weight = 2.56 +/- 0.32 kg, postnatal age = 13.0 +/- 3.2 weeks) were chosen for the study. Pulmonary mechanics and arterial blood gases were measured in the control state and at 30 and 60 minutes following the subcutaneous injection of 5 micrograms/kg terbutaline. There was a significant (p less than 0.001) improvement in lung compliance from baseline values at 30 minutes and at 60 minutes (38%). A significant (p less than 0.05) decrease of 23% in the average pulmonary resistance at 30 minutes and a 26% decrease at 60 minutes from control values were observed. An increase in the I/E ratio occurred in all patients at 60 minutes (p less than 0.01). In addition, clinical improvement was noted in six of eight infants. Administration of terbutaline demonstrated a significant improvement in the pulmonary mechanics of infants with severe BPD.

Bronchopulmonary Dysplasia↗

PubMedDate not supplied

Effect of high-frequency jet ventilation on preterm and rabbit tracheal mechanics.

The effect of high-frequency jet ventilation (HFJV) on both tracheal dimensions and mechanics was evaluated in preterm and term rabbit airways. Seven tracheal segments were studied at 27 days (group I) and 31 days (group II) of gestation, respectively. Tracheal dimensions and segmental pressure-volume relationships were determined before and after 60 minutes of HFJV (peak pressure 20 cm H2O; mean airway pressure 6.7 to 6.8 cm H2O at 10 Hz). Both tracheal lengths and diameters increased significantly (p less than 0.01) in each group and resulted in increased tracheal volumes: 109% in group I (p less than 0.01) and 60% in group II (p less than 0.01). The mean specific tracheal compliance decreased in group I, from 0.036 cm H2O-1 to 0.015 cm H2O-1 (p less than 0.01), and in group II from 0.029 cm H2O-1 to 0.021 cm H2O-1 (p less than 0.01). Furthermore, the collapsing transmural pressure (the pressure required for total collapse of tracheal segments) decreased significantly (p less than 0.01) in both groups. These data demonstrate significant dimensional and mechanical deformation of tracheal segments after HFJV. An increased propensity toward collapsibility is also observed following HFJV. These changes are similar to those with tracheomalacia. The influence of such deformation on tracheal gas flow during HFJV needs to be further investigated.

Animals↗

PubMedDate not supplied

Respiratory and systemic effects of inhaled dexamethasone on ventilator dependant preterm infants at risk for bronchopulmonary dysplasia.

Short-term inhaled dexamethasone therapy was evaluated in a double blind placebo controlled trial in 36 ventilator dependent preterm neonates (BW < 1500 gm, postnatal age > 7 days) who were at risk for bronchopulmonary dysplasia. Pulmonary and systemic effects were compared at early (day 3), late (7-10 days) and post (14 days after initiation) phases of therapy. Airflow mechanics improved as demonstrated by a net 101% improvement in pulmonary resistance (a decrease from 139 to 101 cm H2O/L/s in the dexamethasone treated infants as compared to an increase from 153 to 267 cmH2O/L/s in the placebo treated infants during the early phase of therapy); this was associated with a 45% increase in inspiratory airflow (1.29 +/- 0.43 to 1.87 +/- 0.978 L/min; p < 0.01), and 37% increase in expiratory airflow. These changes resulted in a significant reduction in the work of breathing such that the mean tidal driving pressure significantly decreased from 13.6 cmH2O to 9.4 cm H2O with inhaled steroid administration. Though the brief duration of therapy did not result in cessation of ventilatory support, the level of support was significantly reduced (decreased values of oxygen supplementation, mean airway pressure and oxygenation index and increased ventilatory efficiency index). The inhaled dexamethasone therapy was also associated with systemic absorption of the drug as evidenced by transient but apparently reversible reduction in serum cortisol levels. No systemic side effects of hypertension, hyperglycemia or nosocomial sepsis were observed. These data demonstrate beneficial effects of short-term inhaled dexamethasone on the resistive airflow properties of preterm infants at risk for BPD and may provide adjunctive means to facilitate weaning in the ventilator dependent neonates.

Administration, Inhalation↗

PubMedDate not supplied

Pulmonary function and electrolyte balance following spironolactone treatment in preterm infants with chronic lung disease: a double-blind, placebo-controlled, randomized trial.

OBJECTIVE: To study the effect of spironolactone on dietary electrolyte supplementation, pulmonary function, and electrolyte balance in premature infants with chronic lung disease. STUDY DESIGN: A double-blind, randomized, and placebo-controlled trial was designed to study two groups of low birth weight infants with chronic lung disease at Pennsylvania Hospital. The placebo group received chlorothiazide and a placebo, and the spironolactone group received chlorothiazide and spironolactone during the 2-week study period. A two-tailed t-test was used to determine equivalence between the two groups. RESULTS: Pulmonary compliance, resistance and tidal volume, serum sodium and potassium, and FIO2, were not statistically different between the two groups. The need for sodium and/or potassium chloride did not differ between the two groups, nor did the quantity of each salt. CONCLUSION: The addition of spironolactone did not reduce the requirement for supplemental electrolytes, nor did it improve pulmonary mechanics or electrolyte balance.

Chronic Disease↗