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Biomedical subjects

Y Sivan

Publications and source records attributed to Y Sivan.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effect of positive end-expiratory pressure on respiratory compliance in children with acute respiratory failure.

We studied the effect of positive end-expiratory pressure (PEEP) on the compliance of the respiratory system (Crs) in 25 children (age, 3 weeks to 10 years) requiring mechanical ventilation. Functional residual capacity (FRC) measurements were performed at 2 cm H2O increments, from 0 to 18 cm H2O of PEEP, and the FRC values were regressed versus PEEP. Static Crs, Crs/kg, and specific compliance (Crs/FRC) were calculated for each PEEP level. When FRC normality was reached Crs/kg improved in 15/25 (60%) patients but decreased in 2/25 (8%). Overall, Crs/kg increased from a mean +/- SE of 0.94 +/- 0.09 to 1.35 +/- 0.13 mL/cm H2O/kg (P = 0.003) and Crs/FRC from a mean +/- SE of 0.067 +/- 0.006 to 0.077 +/- 0.007 mL/cm H2O/mL (P = 0.057). The maximum compliance (mean Max Crs/kg, 1.56 +/- 0.12 mL/cm H2O/kg, and mean Max Crs/FRC, 0.089 +/- 0.005 mL/cm H2O/mL) was significantly higher than the compliance at the clinically chosen PEEP level and the compliance at the PEEP that normalized FRC. Maximum compliance was achieved within 4 cm H2O of the PEEP that normalized FRC. In 14/25 (60%) of cases the PEEP at maximum compliance coincided with the PEEP that resulted in FRC normalization. We concluded that static respiratory compliance improves in most (but not all) children with acute respiratory failure when FRC is normalized. Static respiratory compliance reaches maximum levels at PEEP values that are close (but not equal) to those that result in FRC normalization. Thus, assessment of the effect of PEEP on compliance is required in individual patients.

Child↗
PubMed1991

Rib cage to abdominal asynchrony in children undergoing polygraphic sleep studies.

We assessed rib cage (RC) to abdominal (AB) asynchrony in 110 children, aged 1 to 50 months who underwent diagnostic daytime polygraphic sleep studies (PSG), and correlated the results. RC-AB asynchrony was calculated by the phase angle (PA) technique and compared to normal values (0-24 degrees) derived from a separate group of 45 control children, matched for age and weight. Eighty-two of the 110 patients had PSG as part of their evaluation for obstructive sleep apnea. There was a high association between the phase angles and the PSG results (P less than 0.01; Fisher's exact test). PSG was abnormal in 38/82 patients (46%) and the phase angle was increased in 51/82 (62%) (mean +/- SD, 68 degrees +/- 39 degrees; range 28 degrees - 168 degrees) compared to the normal controls (P less than 0.001). Fourteen of the 110 patients had bronchopulmonary dysplasia; of these, PSG and PA results agreed in six normal and seven abnormal studies and disagreed in only one (P = 0.002). Six of 110 patients had Down's syndrome; 5 of 6 had increased RC-AB asynchrony, compared to 3 of 6 who had abnormal PSG. Eight of 110 patients were evaluated for central apnea and hypoventilation; PA was abnormal in 4 of 8, who also had abnormal PSG and in 1 with normal PSG. We conclude that RC-AB measurement by the PA technique may be an important adjunct to the evaluation of breathing disorders during sleep in small children and it may be a good screening test for small children who need PSG.

Abdominal Muscles↗
PubMed1991

Outcome of oncology patients in the pediatric intensive care unit.

We evaluated the outcome of oncology patients in the Pediatric Intensive Care Unit (PICU) from a total of 72 consecutive admissions. Severity of illness and quantity of care were measured by the Physiologic Stability Index (PSI) and the Therapeutic Intervention Scoring System (TISS), respectively. The overall mortality was 51% and was especially high in patients admitted for acute organ system failure (OSF)-66%. Acute respiratory failure was the most frequent OSF (73%) and the most common cause for PICU admission. A poor outcome was associated with severe leucopenia (less than 1000 WBC/mm3, 91% mortality), acute renal failure (94% mortality) and central nervous system deterioration (83% mortality). When the outcome was predicted using a quantitative algorithm the observed mortality was significantly higher than the predicted for all admissions with a PSI higher than 5. Improved scoring systems are required to enable characterization of pediatric cancer patients admitted to the PICU.

Acute Kidney Injury↗
PubMed1991

Laryngomalacia: a cause for early near miss for SIDS.

Six infants had recurrent apnea of infancy episodes (near miss sudden infant death syndrome) during their neonatal period. Physical examination and laboratory investigation were normal. Polygraphic sleep monitoring revealed recurrent obstructive sleep apnea. These infants underwent fiberoptic endoscopy which showed that airway obstruction occurred at the laryngeal orifice as a result of laryngomalacia. It is suggested that laryngomalacia may be a cause for early apnea of infancy.

Airway Obstruction↗
PubMed1990

Adult respiratory distress syndrome in severely neutropenic children.

It has been suggested that polymorphonuclear cells (PMNs) are required for the development of the adult respiratory distress syndrome (ARDS). We investigated the occurrence of ARDS with acute respiratory failure in 30 children with severe neutropenia (less than 500 PMNs/mm3) who met the clinical diagnostic criteria for ARDS and in whom postmortem histopathology findings were available within 7 days of the onset of ARDS. In 26 patients the histopathology was consistent with ARDS. In 12/26 children no white blood cells (WBC) were found in the lung tissue, 10/26 had moderate infiltration of mononuclear cells, 2/26 had massive tumor cell infiltration, and in 2/26 PMNs were found. Thus, in at least 22/26 patients ARDS developed without neutrophilic infiltration of the lungs. The maximum active lung infection rate was found to be 69% (18/26) by endotracheal and post mortem lung cultures and histology. Thus 5/26 children had ARDS without any WBC in the lung tissue. We conclude, as have other studies in adults that the absence of PMNs does not protect children from the development of ARDS and that the mechanism which involves PMNs is probably only one of several pathways for diffuse alveolar damage, some of which is neutrophil-independent.

Adolescent↗
PubMed1990

A double-blind, randomized study of sodium cromoglycate versus placebo in patients with cystic fibrosis and bronchial hyperreactivity.

To evaluate the effects of sodium cromoglycate (SCG) on patients with cystic fibrosis (CF) and with bronchial hyperreactivity, a long-term, double-blind, placebo-controlled, crossover study was performed. Fourteen patients with CF and without asthma (aged 7 to 29 years) and with bronchial hyperreactivity entered the study. Each patient received 8 weeks of 1% SCG nebulizer solution three to four times daily and 8 weeks of placebo. Seven patients received the treatment in the order SCG/placebo and seven patients in the reverse order. Evaluation of SCG effect was performed every 4 to 8 weeks by (1) clinical assessment of symptoms, (2) clinician and patient/parent opinion, (3) pulmonary function tests, and (4) methacholine provocation tests. After two patients were withdrawn for lack of cooperation, the results were evaluated for treatment effect (SCG versus placebo), period effect (whether SCG was administered first or last), or combination of both. No significant difference was found for these parameters for the clinical assessment of symptoms, the patient/parent and clinician opinion, their subjective preferences, the metacholine challenges, or the pulmonary function tests. The study did not demonstrate any benefit from the use of SCG in patients with CF and with bronchial hyperreactivity and does not support the routine use of SCG in patients with CF.

Adolescent↗
PubMed1990

Thoracoabdominal asynchrony in acute upper airway obstruction in small children.

The assessment of the severity and response to therapy of acute upper airway obstruction (UAO) in small children relies on subjective parameters. Using a noncalibrated respiratory inductance plethysmograph (RIP), we quantitated the rib cage (RC) to abdominal (AB) asynchrony and the lag phase in chest wall expansion by the phase angle from the RC versus AB signal curve. Phase angles were obtained in 17 children aged 1 to 50 months with acute UAO and 30 normal control subjects. The phase angle in UAO (16 to 165 degrees; mean = 83.6 degrees) was significantly higher than in control subjects (3 to 25 degrees; mean = 11.5 degrees), p less than 0.001. Following 29 episodes of inhalation treatment with 0.03 ml/kg of racemic epinephrine, the phase angle in the UAO group decreased to 7 to 160 degrees (mean = 38.3; p = 0.001) as the shape of the RC versus AB loop became narrower. In response to the treatment, the clinical severity of UAO decreased and the tidal breathing flow-volume loop improved. A high association was observed between the phase angle and the degree of stridor (p less than 0.005 Fisher's exact test), and in 90% (26 of 29) the changes in the phase angle and in the degree of stridor were in agreement. We conclude that the RC-AB asynchrony in acute UAO can be objectively quantitated by phase-angle measurement from a noncalibrated RIP and is thus suitable for use in infants and small children. The phase angle may be used to assess objectively the response of UAO to therapy.

Abdomen↗
PubMed1990

Early diaphragmatic paralysis. In infants with genetic disorders.

Three infants with recently diagnosed genetic diseases presented with respiratory failure and required assisted ventilation. One infant had spinal muscular atrophy (Werdnig-Hoffmann disease), and two had acid maltase deficiency. The cause of the respiratory failure in all was diaphragmatic paralysis, and they became ventilator dependent. Early diaphragmatic paralysis must be considered as a manifestation of genetic neuromuscular disorders.

Female↗
PubMed1990

An automated bedside method for measuring functional residual capacity by N2 washout in mechanically ventilated children.

Beside measurement of functional residual capacity (FRC) in ventilated children is impractical. Using a simple technique based on open circuit N2 washout, we measured FRC in ventilated children. The system was evaluated in the laboratory and in patients. Using a mechanical lung, the reproducibility of 200 studies over a range of 100-500 mL at each of four different flow rates (10 determinations at each level) was very high with a mean coefficient of variation of 2.3% (range 0.5-5.1%). Linearity of the integrated N2 signal for volumes of 100-500 mL washed out at different flow rates was excellent (range 7.4-17.9 L/min), r = 0.99. The mean difference between measured and preset mechanical lung volumes was 2.4% (range 0-4.6%). In vivo, reproducibility of six to 10 FRC determinations in each of 30 children gave a mean coefficient of variation of 2.7%. Comparison to the conventional Douglas bag collection method showed a high correlation (r = 0.97). We conclude that this is an easy, highly reproducible, and accurate method for FRC determination suitable to ventilated infants and children.

Child↗
PubMed1990

Functional residual capacity in ventilated infants and children.

Positive end expiratory pressure (PEEP) is an accepted treatment for children with acute respiratory failure secondary to restrictive lung diseases. Using a simple technique based on open circuit nitrogen washout, we determined the functional residual capacity (FRC) in 25 ventilated children (age 3 wk-10 y) with acute respiratory failure secondary to restrictive lung disease (pulmonary edema, bilateral pneumonia). FRC measured at a physiologic level of PEEP (2-4 cm H2O) was 45.0 +/- 3.6% (mean +/- SEM; range 12-80%) lower than normal predicted values. At the PEEP level chosen clinically (4-10 cm H2O, mean = 6.0), the FRC was below normal predicted values for nonintubated children by a mean of 31.8% (range 0-73%) (p = 0.0001) and only seven patients (28%) had FRC within 20% below predicted normal values. FRC normalized at PEEP levels of 6-18 cm H2O (mean = 11.6), which was up to 200% above the clinically chosen PEEP level. In six children without lung disease who were ventilated at a PEEP level of 2-4 cm H2O, the FRC was within normal range in two, but significantly higher (by 45%) in the other four. We conclude that FRC in ventilated children with acute restrictive lung disease is significantly lower than normal and the clinically chosen PEEP fails to normalize the FRC in most of the cases.

Child↗