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Biomedical subjects

C Maayan

Publications and source records attributed to C Maayan.

At least 55 records · Page 3Linked to original sources
PubMed1989

Breath-by-breath respiratory timing and volume control during periodic breathing.

We examined the control of respiratory pattern during non-rapid-eye-movement sleep-related periodic breathing (PB) in adults, with and without hypoxia. We analyzed 186 cycles of PB from 18 epochs occurring in eight subjects; the mean (+/- SD) cycle duration was 30.8 +/- 8.4 s. Significant oscillations occurred in inspired tidal volume (VT), inspiratory duration (TI), mean inspired flow, inspired minute ventilation, and expiratory duration (TE) (P less than 0.005). For each epoch of PB, moving cross-correlation (MCC) functions were employed to describe the time-dependent intervariable relationships between 1) TI vs. TE, 2) VT vs. TE, and 3) VT vs. breath duration (TT) as synchronization, a strong and consistent intervariable correlation; relative coordination (RC), a weaker interaction characterized by an unstable MCC function oscillating at a subharmonic of the PB frequency; or as independence, with no statistical evidence of interaction. Fourteen epochs showed RC between TI and TE, 11 and 12 of which also showed RC between VT and TE, and VT and TT, respectively. In 4 epochs negative synchronization was exhibited by all three variable pairs. In no case were the oscillations between any pair of variables independent. The modes of coupling between variables were not correlated to O2 saturation, end-tidal CO2 levels, or inspired O2 level. We conclude that during sleep-related PB a nonrandom but weak coupling usually exists between TI and TE, VT and TE, and VT and TT.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

Immediate effect of various treatments on lung function in infants with cystic fibrosis.

The immediate effect of four different modes of treatment was assessed by lung function tests on 19 infants with cystic fibrosis (CF) during the first year of life. The regimens were applied in a randomized fashion and consisted of aerosol inhalation of salbutamol (n = 8; SAL), aerosol inhalation of N-acetyl cysteine (n = 5; AC), chest physiotherapy (n = 6; CPT), and combined treatment with aerosol inhalation of SAL and AC followed by CPT (n = 6; COMB). Pulmonary function was measured before and shortly after therapy with each mode of treatment. Thoracic gas volume (Vtg) and specific airway conductance (SGaw) were measured by an infant whole body plethysmograph, and forced expiratory flow at resting lung volume (VmaxFRC) was determined with a thoraco-abdominal squeeze jacket. There was no correlation between baseline lung function and changes in any parameter due to treatment. Overall group comparison showed that the combined therapy resulted in a significant improvement in lung function when compared to any of the three treatments applied separately. There was no significant change in lung volumes in any individual group, but SGaw and VmaxFRC showed a small but significant improvement following the COMB treatment when compared with AC or CPT.

Acetylcysteine↗
PubMed1988

Lung function in infants with cystic fibrosis.

Lung function was measured in 28 infants with cystic fibrosis and repeated in 17 of the infants during the first year of life. Thoracic gas volume (TGV) and specific airway conductance (sGaw) were measured plethysmographically and maximum forced expiratory flow at functional residual capacity (VmaxFRC) was derived from the partial expiratory flow-volume curve. At the time of the initial evaluation respiratory function was correlated with the clinical condition of the infants but not with age. There was a good correlation between sGaw and VmaxFRC when both were expressed as percentages of the predicted normal values. On the basis of the normal range for sGaw the infants were divided into two groups. Group A (n = 9), who had normal sGaw, were younger and had a lower clinical score and normal VmaxFRC and TGV values. Group B (n = 19), who had low sGaw, had increased TGV and decreased VmaxFRC. There was no correlation with age for any measure of lung function for the population as a whole. Repeat testing was undertaken at intervals in 17 representative infants. In most of these infants the relation between sGaw and VmaxFRC was maintained; there was no evidence that VmaxFRC was affected before sGaw. There was no functional evidence that the earliest changes in cystic fibrosis occur in small airways, as reflected by changes in VmaxFRC in infancy.

Airway Resistance↗
PubMed1987

Evaluation of autonomic dysfunction in familial dysautonomia by power spectral analysis.

We examined the nature and extent of the autonomic control defect in patients with autonomic dysfunction using power spectral analysis of heart rate fluctuations. Heart rate variability and respiratory patterns were monitored and discrete blood pressure measurements were made during supine and standing positions in 10 ambulatory patients with familial dysautonomia and in controls. Postural hypotension without compensatory tachycardia was confirmed in the patients upon standing. The balance between sympathetic and parasympathetic activity was compared in both positions by quantifying the power of the low (0.04-0.095 Hz) and high (respiratory) frequency fluctuations in instantaneous heart rate. After changing from supine to standing position there was a small decrease in the low frequency power of heart rate fluctuations in the patients as opposed to a significant increase in controls. The mean power of fluctuations occurring at high frequency decreased only slightly in the patients compared to a marked decrease in the controls. We conclude that the fall in blood pressure, lack of appropriate heart rate modulation, and failure to increase low frequency heart rate power which occurred in the patients upon standing, are all due to lack of increased sympathetic output under the influence of gravity. The failure to decrease power in the respiratory frequency peak in the patients, suggests an abnormal retention of parasympathetic activity. This may be explained by parasympathetic compensation for the substantial sympathetic loss, or by a lack of appropriate inhibition of parasympathetic tone from baroreceptors or supraspinal structures.

Adult↗
PubMed1987

Incidence of familial dysautonomia in Israel 1977-1981.

The incidence of all diagnosed cases of familial dysautonomia in Israel among Ashkenazi Jews from 1977-1981 was 27/100,000 or 1/3703. This incidence is higher than that previously reported in Israel in 1967 or 8.3/100,000 (1/12,048) (Moses et al. 1967). It is also higher than that of North American Ashkenazi Jews in 1970, when the rate was 5-10/100,000 (1/10,000-20,000) (Brunt & McKusick 1970). This higher incidence could be explained by current awareness of the diagnosis, or by the emergence of more cases.

Dysautonomia, Familial↗
PubMed1987

Chloroquine treatment in desquamative interstitial pneumonia.

An infant presented with failure to thrive, tachypnoea, and hypoxia reversed by oxygen. Lung function showed decreased pulmonary compliance; lung biopsy showed desquamative interstitial pneumonitis. Chloroquine 10 mg/kg/day resulted in improvement and relapse when temporarily stopped. The patient was completely asymptomatic during four years' treatment and six months after stopping treatment.

Chloroquine↗
PubMed1987

Comparison of budesonide and beclomethasone dipropionate for treatment of asthma.

Beclomethasone dipropionate (BDP) and budesonide (BUD) were each given in a dose of 200 micrograms twice daily by metered dose inhaler to 10 asthmatic children already dependent on treatment with steroids. In a double blind randomised crossover study each course lasted one month. No clinically important differences were found between the two treatments when symptom scores, symptom free days, additional use of salbutamol, and results of lung function tests were considered. Metyrapone mildly reduced the plasma concentration of 11-deoxycortisol in two patients during treatment with budesonide, and in four during treatment with beclomethasone. It is concluded that although they are usually safe, both drugs may cause mild adrenal suppression when given in a dose of 200 micrograms twice daily.

Administration, Inhalation↗
PubMed1987

Bradycardia associated with hiatal hernia and gastroesophageal reflux relieved by surgery.

A man known to have familial dysautonomia presented with a cardiac arrhythmia due to development of hiatal hernia and gastroesophageal reflux. Preoperative symptoms and assessment are described including use of power spectrum analysis of heart rate fluctuations which was consistent with enhanced parasympathetic stimulation. After surgical repair of hiatal hernia and fundoplication, bradycardia resolved, gastroesophageal reflux symptoms subsided, and the power spectrum analysis of heart rate confirmed decreased parasympathetic influence. Power spectrum analysis proved to be a useful adjunct in confirming preoperative autonomic imbalance and assessing the postoperative result. It is concluded that in individuals with disorders such as familial dysautonomia that are associated with autonomic dysfunction, cardiac arrhythmias may be a sign of esophageal pathology. Thus, cardiac evaluations should be accompanied by investigation of gastroesophageal structure and function and appropriate treatment may prevent a catastrophic arrhythmia.

Adult↗
PubMed1986

Effect of mechanical ventilation and volume loading on left ventricular performance in premature infants with respiratory distress syndrome.

Left ventricular (LV) performance was assessed by echocardiography in 19 premature infants with severe respiratory distress syndrome. Measurements of LV size and function were made from digitized M-mode echocardiographic data in 14 babies (group 1) before and during treatment with mechanical ventilation and positive end-expiratory pressure. During ventilation, maximum LV dimension decreased (p = .001) as did peak filling rate (p = .01). LV shortening fraction decreased slightly (p = .05). There were marked reductions in calculated stroke volume (SV) (p = .001) and cardiac output (p = .0001) but systemic BP was unchanged, presumably due to peripheral vasoconstriction. The effect of simultaneous volume loading was studied in five other babies (group 2) who were ventilated under similar conditions. Blood transfusion with packed cells (10 mg/kg) prevented the fall in LV filling rate, while LV dimensions (max, p = .01; min, p = .02), SV (p = .05), cardiac output (p = .05), and systolic BP (p = .05) increased. This indicates that a low preload was responsible for the decreases observed in group 1.

Blood Cells↗
PubMed1986

Airway resistance measurements throughout the respiratory cycle in infants.

Using a constant-volume infant whole-body plethysmograph containing a heated rebreathing bag, we have been able to measure airway resistance (Raw) throughout the respiratory cycle using a computer-based technique. Data from the plethysmograph transducers are sampled at 60 Hz for the calculations and Raw is calculated at each point sampled during the breath, with appropriate corrections for absolute lung volume. It was found that in most cases Raw varied less with respect to tidal volume than to tidal flow. Various patterns of Raw change in relation to tidal volume were found. These included an elevated but relatively constant resistance, a progressively rising expiratory resistance, and in 3 infants with laryngomalacia, a progressively rising inspiratory resistance. It was also found that the dynamic performance of the rebreathing bag was such that considerable errors would occur if apparatus resistance was assumed to be constant and so the actual apparatus resistance at each point was subtracted from the total resistance to give Raw. In conclusion, Raw is not constant throughout the respiratory cycle in infants and the pattern of change conveys additional information.

Airway Resistance↗
PubMed1986

Can thoracic gas volume be measured in infants with airways obstruction?

Thoracic gas volume (Vtg) was measured in a whole-body, infant plethysmograph in 46 infants with recurrent wheezing after bronchiolitis, 25 infants with cystic fibrosis, and 6 infants without overt lung disease during the first 13 months of life. When related to weight or length, 56.5% of the bronchiolitic infants had low Vtg values, which were more than 2 SD below their predicted normal. The Vtg of the other groups was normal or above. The bronchiolitic infants with Vtg values in the normal range had more severe airways obstruction and it is probable that their Vtg values were also underestimated. Investigation of possible sources of technical or experimental error failed to reveal any explanation for the low Vtg in the bronchiolitic infants. In 5 infants, Vtg determined plethysmographically was correlated linearly to functional residual capacity determined by helium dilution, although Vtg values were greater in all. The administration of albuterol or treatment with steroids failed to make significant changes in Vtg in the bronchiolitic infants. It is suggested that there is a physiologic basis for the presumed underestimation of Vtg in wheezy infants after bronchiolitis, either because of uneven alveolar pressure changes within the chest leading to the effective exclusion of a portion of the lung volume or because there are some alveolar units with very low compliance that change little in volume during respiratory efforts against an occlusion. These results call into question the validity of the plethysmographic measurement of Vtg or airway resistance in these infants. If the error in Vtg is due to uneven alveolar pressure changes, it is suggested that the calculated specific airway conductance is probably correct.

Airway Obstruction↗
PubMed1986

Nemaline myopathy as a cause of sleep hypoventilation.

Two siblings, a 14.5-year-old boy and his 11.5-year-old sister, with congenital nemaline myopathy presented with severe respiratory failure and, in the case of the older patient, with cor pulmonale and systemic hypertension. The children were treated initially by continuous mechanical ventilation, but after a few weeks they only required ventilation at night. At the start of treatment, both were found to have a decreased ventilatory response to CO2 which apparently improved during 4 to 5 years of follow-up treatment. It has not been possible to wean them from nocturnal mechanical ventilation, but during the daytime they attend school and function almost normally. It is postulated that respiratory failure in nemaline myopathy may not be related to the severity of the muscle weakness but may result from a disturbance of the feedback required for normal control of breathing.

Adolescent↗
PubMed1985

The surgical management of children with familial dysautonomia.

Familial dysautonomia (FD) is a rare incurable genetic disorder with multisystem involvement. Most of its clinical manifestations are related to disorders of the autonomic nervous system. The disease is associated with specific disturbances of the upper gastrointestinal tract: pharyngoesophageal dyskinesia, gastroesophageal reflux, and prolonged gastric emptying. About 40% of the dysautonomic children manifest repeat vomiting crises. In view of the extensive gastrointestinal symptomatology, children with FD are prone to repeated aspiration pneumonia and chronic respiratory failure, while inadequate calory and fluid intake may lead to a chronic state of hypovolemia and severe failure to thrive. Control of vomiting, prevention of aspiration due to abnormal swallowing, and the assurance of adequate calory intake are three major objectives in the treatment of the dysautonomic child. Medical treatment of the gastrointestinal disorders using different drugs has had limited success. This study reviews the surgical experience in ten children with FD. The type of the procedure used was determined by the severity of the upper GI disturbances. Nine children underwent gastroesophageal Nissen fundoplication and gastrostomy. In seven of them, a pyloroplasty was added. Gastrostomy alone was done in one patient only. Postoperative complications included transient dysphagia in four patients, gastric dilatation in four patients, and dumping syndrome in one. There has been no incidence of immediate postoperative death. One child died 6 months after operation from severe and irreversible respiratory failure. Following operation, the patients still suffered from dysautonomic crises but these were not associated with vomiting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Idiopathic infantile arterial calcification: a case report and review of the literature.

Idiopathic infantile arterial calcification (IIAC) was diagnosed radiologically in an infant with sudden onset of heart failure. The clinical picture, radiological, laboratory and postmortem findings, are described in detail. There was no family history and a metabolic abnormality could not be detected. Calcifications of major arteries and particularly ligaments are pathognomonic radiologic signs of this condition but diagnosis of IIAC during life has been established only rarely. The value of early diagnosis is emphasised.

Calcinosis↗
PubMed1982

Incidence of convulsions and encephalopathy in childhood Shigella infections. Survey of 117 hospitalized patients.

Of 117 children ill enough to be hospitalized with Shigella gastroenteritis, 53 per cent had neurologic symptoms, the majority during the onset of high fever: 11 per cent had convulsions alone, 22 per cent had encephalopathy alone, and 20 per cent had convulsions and encephalopathy. The neurologic manifestations preceded the gastrointestinal symptoms in one fourth of the patients. Shigella sonnei was the predominant organism found in this study, especially in patients with neurologic symptoms.

Age Factors↗