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S J Boros

Publications and source records attributed to S J Boros.

At least 19 recordsLinked to original sources
PubMed1992

Effect of rapid thoracic compression on the cerebral blood flow-velocity patterns of small infants.

We measured the middle cerebral artery (MCA) flow-velocities of 12 small infants (mean weight, 2,882 +/- 602 g) before, during, and after the rapid thoracic compression (RTC) maneuvers of partial forced expiratory flow-volume studies. Cerebral flow-velocities were measured using transcranial Doppler ultrasonography. RTC increased MCA end diastolic flow-velocities and Pourcelot indices of all infants (P less than 0.001). These values returned to baseline immediately after the release of chest compression. We also measured the MCA flow-velocities of several preterm infants during their normal daily activities. The changes in flow-velocity patterns observed during normal daily life were similar to those observed during RTC. These findings demonstrate that RTC produces real, but likely not pathologic, changes in cerebral blood flow-velocities.

Blood Flow Velocity↗
PubMed1991

Acute airway injury during high-frequency jet ventilation and high-frequency oscillatory ventilation.

BACKGROUND AND METHODS: We compared tracheal histologic injury patterns, airway pressure (Paw) requirements, and in vivo and in vitro estimate of airway humidification in 13 adult cats with normal lungs mechanically ventilated for 16 hr. Six animals were treated with high-frequency jet ventilation at 400 breaths/min and seven animals with high-frequency oscillatory ventilation at 900 breaths/min. RESULTS: Peak airway pressure, Paw, mean Paw, and end-expiratory pressure requirements were significantly higher for high-frequency oscillatory ventilation as compared with high-frequency jet ventilation for similar gas exchange (p less than .01). While in vivo estimates of airway humidification suggested progressively greater H2O delivery into the respirator circuit, and therefore the airway, with higher frequencies, the in vitro study suggested similar relative humidities of the delivered gases during both types of mechanical ventilation. Tracheal injury, measured using a semiquantitative scoring system, was scored similarly for both ventilators studied despite the higher pressure requirements seen with the high-frequency oscillator. CONCLUSIONS: In this animal model, high-frequency ventilation using either jet or oscillation techniques produced similar inflammatory tracheal damage despite differences in Paw exposure and humidity.

Air Pressure↗
PubMed1990

Effect of spontaneous and mechanical breathing on dynamic lung mechanics in hyaline membrane disease.

We measured then compared the dynamic lung mechanics of spontaneous breaths and mechanical breaths in 9 mechanically ventilated neonates with hyaline membrane disease. All were receiving intermittent mandatory ventilation. All breathed spontaneously between ventilator breaths. Tidal volume, transpulmonary pressure, dynamic lung compliance, airways resistance, and peak inspiratory and peak expiratory gas flows were determined for both the mechanical and the spontaneous breaths. The mechanical breaths consistently had larger tidal volumes, higher transpulmonary pressures, higher airway resistance, and lower lung compliance values (P less than 0.05). Peak inspiratory and expiratory gas flows were also higher (P less than 0.01) during mechanical breathing. The spontaneous breaths generated by patients and the mechanical breaths generated by mechanical ventilators are different. The lung mechanics measurements of these two different types of breathing should be collected, analyzed, and reported separately.

Humans↗
PubMed1989

Comparison of high-frequency oscillatory ventilation and high-frequency jet ventilation in cats with normal lungs.

Four adult cats received alternating high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) at equivalent proximal airway pressures. Physiologic measurements were made before and after each ventilator change. Proximal airway pressures were then adjusted as necessary to reestablish normal pH and PaCO2 values. Aortic, pulmonary artery, and central venous pressures were monitored. Cardiac outputs were measured. Pulmonary and systemic vascular resistance, intrapulmonary shunt, and alveolar-arterial oxygen gradient were determined. Following the change from HFOV to HFJV at similar proximal airway pressures, HFJV always produced higher pH values (P less than 0.0001), higher PaO2 values (P less than 0.05), lower PaCO2 values (P less than 0.0001), as well as higher cardiac outputs (P less than 0.01), lower pulmonary artery pressures (P less than 0.001), and lower pulmonary vascular resistances (P less than 0.001). Following the reciprocal crossover, from HFJV to HFOV, HFJV pH values were again higher (P less than 0.001), and PaCO2 values were again lower (P less than 0.001). A comparison of HFOV and HFJV at similar pH and PaCO2 values showed that HFOV consistently required higher peak inspiratory pressures (P less than 0.001), higher mean airway pressure (P less than 0.001), and higher pressure wave amplitudes (P less than 0.001). Under the circumstances of this study, HFJV produced better gas exchange at lower proximal airway pressures.

Airway Resistance↗
PubMed1989

Determining optimum inspiratory time during intermittent positive pressure ventilation in surfactant-depleted cats.

This study compares two methods of selecting inspiratory time (Ti) during mechanical ventilation. One selects a standard Ti producing a brief inspiratory pressure plateau (P). The other uses simultaneous pressure, flow and tidal volume (VT) waveforms, generated by a computer-assisted lung mechanics analyzer, to reduce Ti to the point where Vt ceases to accumulate and flow returns to zero. This method does not produce a pressure plateau (NP). Following saline lung washout, ten intubated, paralyzed surfactant-depleted cats were ventilated with pressure-preset infant ventilators at constant measured VT and rates. Five animals were initially ventilated with P (Ti = 0.98 +/- 0.02 s) and five with NP (Ti = 0.77 +/- 0.10 s). Ti was then varied to produce P or NP by using a four-period crossover design. All other ventilator variables remained constant. Intravascular pressures, thermodilution cardiac outputs, arterial and mixed venous blood gases and oxygen saturations, airway pressures, Ti, VT, and gas flows were measured; respiratory system mechanics, alveolar-arterial oxygen gradients, and intrapulmonary shunts were determined for each study period. When P and NP states were compared, only mean airway pressures differed (10.1 vs. 8.9 cmH2O; P less than 0.001). Blood gas values, intravascular pressures, cardiac output, and respiratory system mechanics were all similar. Under the conditions of this study, there was no advantage to prolonging Ti beyond the point where VT ceased to accumulate.

Airway Resistance↗
PubMed1988

Identifying lung overdistention during mechanical ventilation by using volume-pressure loops.

We measured the pulmonary mechanics of 23 mechanically ventilated neonates. Airway pressures, inspiratory and expiratory flows were simultaneously measured. Values for respiratory system mechanics were then derived from these data by using a personal computer and a special software program. Volume-pressure (V-P) loops and respiratory system compliance values were determined for representative mechanical breaths. Twelve infants had normal-appearing V-P loops. Eleven had V-P loops characteristic of lung overdistention, showing decreasing changes in volume with progressive increases in pressure. To quantify this visual observation, we determined the change in compliance during the last 20% of inspiration (C20). We then compared this value to the total compliance value for the entire breath (C) using the ratio C20/C. Mean values for C, C20, and C20/C were compared for the two patient groups. Total respiratory system compliance values were similar. C20 values were decreased in those patients with V-P loops showing overdistention. C20/C values were significantly decreased in those patients with V-P loop evidence of overdistention. Patients with V-P loop evidence of overdistention all had C20/C values less than 0.8. Those with normal-appearing V-P loops all had C20/C values greater than 1.0. The C20/C ratio appears to effectively quantitate visual V-P loop evidence of lung overdistention during mechanical ventilation.

Barotrauma↗
PubMed1987

Short-term dexamethasone therapy for bronchopulmonary dysplasia: acute effects and 1-year follow-up.

Eight ventilator-dependent infants with bronchopulmonary dysplasia (BPD) were treated with dexamethasone (0.5 mg/kg/day). Therapy was initiated at 19.3 +/- 3.9 days of age, continued at the initial dose for 7 days, then tapered over 2 weeks. The clinical course of these infants with BPD was compared to that of 8 similar ventilator-dependent infants with uncomplicated hyaline membrane disease (HMD). At study entry, the BPD patients had significantly higher ventilator rates, peak inspiratory pressures, mean airway pressures, alveolar-arterial oxygen gradients and fraction of inspired oxygen (FiO2) values. After 7 days of dexamethasone therapy, ventilator rates, peak inspiratory pressures, mean airway pressures, FiO2 values and alveolar-arterial oxygen gradients improved significantly. At this time, ventilator rates, peak inspiratory pressures and FiO2 values were similar to those of patients with uncomplicated HMD. BPD patients were extubated after 6.5 +/- 2.4 days of therapy. The incidences of septicemia, rickets and retinopathy of prematurity were similar in the BPD and uncomplicated HMD patients. Most dexamethasone-treated patients developed arterial hypertension during the first 48 h of therapy. Blood pressures returned to normal within 7 days of stopping therapy. All BPD patients had cosyntropin responses tested 5.5 +/- 2.6 weeks after stopping therapy. Six were normal. Two had inadequate responses. At 1 year adjusted age, the dexamethasone-treated BPD infants and HMD infants had similar radiographic bone ages, similar growth patterns and similar scores on the Bayley infant development scale. Dexamethasone was useful in the treatment of early BPD. Used as short-term therapy, the drug had minimal complications and no long-term sequelae.

Apgar Score↗
PubMed1987

Necrotizing tracheobronchitis: a newly recognized cause of acute obstruction in mechanically ventilated neonates.

Necrotizing tracheobronchitis (NTB) is an acute inflammatory lesion of the lower airway which can result in total airway obstruction. While potentially treatable, this lesion has been described predominantly in autopsy or animal studies. We observed clinical symptoms which reflect development of this lesion. Symptoms of acute airway obstruction (hypercarbia, respiratory acidosis, decreased chest wall movement) occurred in eight neonates undergoing treatment with high-frequency jet ventilation; five patients treated with HFJV were studied without signs of obstruction. Emergency bronchoscopy using a rigid bronchoscope was performed in the intensive care unit. The diagnosis of NTB was made by the observation of hyperemia, intraluminal debris, or the appearance of eschar formation. Necrotic debris was removed using forceps and/or suction as necessary. All patients survived treatment. Seven were long-term survivors, all with bronchopulmonary dysplasia. In patients who died, autopsy evaluation of the airway revealed a characteristic picture consisting of necrosis, neutrophil infiltration, epithelial erosion, and intraluminal obstruction.

Airway Obstruction↗
PubMed1987

Neonatal transcutaneous arterial oxygen saturation monitoring.

Transcutaneous arterial oxygen saturation (TcSaO2) and directly measured oxygen saturation values from 25 neonates with a variety of respiratory problems were compared. At arterial oxygen saturations above 60 per cent, TcSaO2 measurements were accurate and reliable. However, SaO2 values less than 60 per cent were significantly overestimated by TcSaO2, so careful laboratory confirmation of low SaO2 values is necessary. The use, accuracy, and limitations of this noninvasive transcutaneous technique for measuring arterial hemoglobin-oxygen saturation are discussed.

Arteries↗
PubMed1986

Hydrops fetalis and chromosomal trisomies.

Three patients with trisomy 21 and one with trisomy 13 associated with nonimmunologic hydrops fetalis are presented. Analysis of previous nonimmunologic hydrops fetalis, which included chromosomal trisomies, and the present study yields an overall incidence of 7% for chromosomal trisomy disorders in live-born infants with nonimmunologic hydrops fetalis. Our data emphasize the need for chromosomal analysis of neonates with nonimmunologic hydrops fetalis.

Chromosomes, Human, 13-15↗
PubMed1986

Necrotizing tracheobronchitis: a complication of high-frequency ventilation.

The tracheobronchial histopathologic findings in eight neonates who died after treatment with high-frequency jet ventilation (HFJV) were compared with those in eight similar infants who died after treatment with conventional mechanical ventilation. The HFJV and conventionally treated groups were matched as closely as possible for birth weight, gestational age, and duration of mechanical ventilation. A 4-point, nine-variable histologic scoring system was used to grade tissue changes in the trachea, carina, and mainstem bronchi. The patients who received HFJV had significantly more histologic damage in their tracheas, carinas, and right and left mainstem bronchi. At all levels of the airway examined, HFJV was associated with more inflammation, greater losses of ciliated epithelium, and more mucus within the lumen of the airway than was conventional mechanical ventilation.

Bronchi↗
PubMed1986

High-frequency ventilation and tracheal injuries.

Recent reports linking serious tracheal injuries to various forms of high-frequency ventilation prompted this study. We compared the tracheal histopathology seen following standard-frequency, conventional mechanical ventilation with that seen following high-frequency, conventional mechanical ventilation, and two different forms of high-frequency jet ventilation. Twenty-six adult cats were examined. Each was mechanically ventilated for 16 hours. Seven received standard-frequency, conventional mechanical ventilation at 20 breaths per minute. Seven received high-frequency, conventional mechanical ventilation at 150 breaths per minute. Six received high-frequency jet ventilation at 250 breaths per minute via the Instrument Development Corporation VS600 jet ventilator (IDC). Six received high-frequency jet ventilation at 400 breaths per minute via the Bunnell Life Pulse jet ventilator (BLP). A semiquantitative histopathologic scoring system graded tracheal tissue changes. All forms of high-frequency ventilation produced significant inflammation (erosion, necrosis, and polymorphonuclear leukocyte infiltration) in the trachea in the region of the endotracheal tube tip. Conventional mechanical ventilation produced less histopathology than any form of high-frequency ventilation. Of all of the ventilators examined, the BLP, the ventilator operating at the fastest rate, produced the greatest loss of surface cilia and depletion of intracellular mucus. IDC high-frequency jet ventilation and high-frequency, conventional mechanical ventilation produced nearly identical histologic injuries. In this study, significant tracheal damage occurred with all forms of high-frequency ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Neonatal high-frequency jet ventilation: four years' experience.

During a 4-year period, 34 neonates were treated with high-frequency jet ventilation (HFJV) using two different HFJV systems. Twenty-three of the neonates had severe pulmonary air leaks, five had congenital left-sided diaphragmatic hernias, and six had end-stage respiratory failure without pulmonary air leaks. The two HFJV systems performed similarly in all pathologic conditions. Following HFJV, arterial blood gas values improved in 28 of the 34 patients (82%). Eleven patients (32%) ultimately survived. Of 23 patients with pulmonary air leaks, 17 (74%) improved, nine (39%) survived. One infant with diaphragmatic hernia and one with end-stage respiratory failure survived. Ten of 12 patients (85%) who died following eight or more hours of HFJV had significant tracheal histopathology in the region of the endotracheal tube tip. The lesions ranged from moderate erythema to severe necrotizing tracheobronchitis with total tracheal obstruction. HFJV can be useful in the treatment of severe pulmonary air leaks in neonates and may prove useful in the treatment of congenital diaphragmatic hernias. However, HFJV produces inflammatory injuries in the proximal trachea. More clinical and laboratory studies are needed to define the relative risks and benefits of this new therapy.

Blood Gas Analysis↗
PubMed1979

Variations in inspiratory:expiratory ratio and airway pressure wave form during mechanical ventilation: the significance of mean airway pressure.

Twelve neonates with severe lung disease were studied while mechanically ventilated with volume pre-set infant ventilators, using different I:E ratios and different airway pressure waves. While FIO2 tidal volume, respiratory rate, and PEEP remained constant, I:E ratios were increased, first by reducing inspiratory flow rate, which produced a triangular pressure wave, and then by using an inspiratory time hold mechanism, which produced an inspiratory plateau or squared pressure wave. Peak inspiratory pressure, mean airway pressure, PaO2, PaCO2, pH, and blood pressure were measured and compared for each I:E ratio and pressure wave combination. In all patients, increases in oxygenation appeared to be directly related to increases in MAP. Optimum oxygenation and ventilation occurred with the I:E ratio and pressure wave combination that produced the highest MAP. Because MAP changes with any alteration in PEEP, I:E ratio, or airway pressure wave, it is a clinically useful composite measure of all pressures transmitted to the airways by a mechanical ventilator.

Humans↗
PubMed1979

A tdic(5;15)(p31;p11) chromosome showing variation for constriction in the centromeric regions in a patient with the cri du chat syndrome.

Some dicentric chromosomes show only one primary constriction at metaphase and behave in cell division as if they are monocentric. The few previous reports of tdic (translocation dicentric) chromosomes showing one morphologic indicate that among the cells of an individual the same centromere consistently shows the primary constriction. The present case deals with a tdic(5;15)(p13;p11) chromosome that is an exception to this pattern. Scoring 98 GTG-, C-, and QFQ-banded metaphases specifically for primary constrictions revealed 15 (15%) containing a tdic chromosome with a single primary constriction. Among these chromosomes, 8 (8%) were at the chromosome 15 centromere and 7 (7%) were at the chromosome 5 centromere. The remaining 83 (85%) tdic chromosomes showed two primary constrictions. We analyzed a total of 172 metaphases from peripheral blood, and all except 3 (1.7%) contained the tdic chromosome. Among these three cells, the tdic chromosome was broken in two and absent in one, which indicates that there was some unstable separation of this dicentric in cell division. In two metaphases, there was a chromatid gap at the site of one centromere. Possibly, the absence of certain primary constrictions was associated with deletion of centromeres. This mechanism may be a continual source for additional centromere inactivation during the life of this patient. This case demonstrates that for some dicentrics either centromere may become nonfunctional and inactivation can occur more than once within an individual. The karyotype of this patient was 45,XX,tdic(5;15)(p31;p11). Thus, she was monosomic for about 3/4 of the chromosome 5 short arm. Clinically, this infant had a shrill catlike cry and facies of the cri du chat syndrome.

Centromere↗