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Biomedical subjects

S Godfrey

Publications and source records attributed to S Godfrey.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1988

Enhancement of theophylline clearance by intravenous albuterol.

Co-administration of intravenous albuterol and theophylline resulted in increased theophylline clearance in a child with severe asthma. This required a threefold increase in theophylline dosage to maintain therapeutic serum theophylline concentrations. The possible effect of intravenous albuterol on theophylline metabolism was further supported by a 50 percent decrease in theophylline clearance upon discontinuation of albuterol and a second increase in its clearance when albuterol was readministered. To the best of our knowledge, this is the first documentation of enhanced theophylline clearance by albuterol.

Albuterol↗
PubMed1988

Respiratory mechanics and intrinsic PEEP during ketamine and halothane anesthesia in young children.

Static compliance of the respiratory system (Crs) was measured by the interrupter technique in 18 anesthetized children to compare the effects of ketamine on Crs with those of halothane. Crs was the slope of the pressure-volume (P-V) curve obtained by repeated brief airway occlusions throughout relaxed expiration, and the intercept of the P-V curve on the pressure axis was the intrinsic positive end-expiratory airway pressure (PEEPi). Expiratory time (Te) was measured during a period of quiet breathing, and the passive expiratory time constant (tau) was measured during the relaxed expiration after an end-inspiratory occlusion. Nine children were anesthetized with a continuous infusion of ketamine and a matching group of nine children inhaled halothane in oxygen. Crs was significantly greater in the ketamine group (22.8 +/- 6.2 ml/cm H2O) than in the halothane group (15.7 +/- 5.5 ml/cm H2O). The tau value was also significantly greater in the ketamine group. Mean PEEPi in the ketamine group was 2.3 +/- 1.8 cm H2O and in the halothane group was 0.4 +/- 0.8 cm H2O. PEEPi correlated inversely with Te/tau according to a logarithmic function. It was concluded that, in children anesthetized with ketamine, Crs is significantly greater than that in children anesthetized with halothane, and the resultant prolongation of tau and decreased Te/tau with ketamine anesthesia lead to increased PEEPi.

Airway Resistance↗
PubMed1988

Respiratory heat/water loss alone does not determine the severity of exercise-induced asthma.

Respiratory heat loss (RHL) or water loss (RWL) have been proposed as possible triggering factors in exercise and hyperventilation-induced asthma (EIA and HIA). It has recently been demonstrated that exercise intensity and climatic factors are both important in determining the severity of EIA. Eight young asthmatics performed both exercise and isocapnic hyperventilation (IHV) manoeuvres under identical climatic conditions, as part of our investigation of these interactive factors which determine the severity of the asthmatic response. It was found that, when challenged at low ventilatory levels, exercise produced a significantly attenuated asthmatic response compared to IHV. The fall in forced expired volume in 1 sec (delta FEV1) following exercise was 15 +/- 4% as compared with 27 +/- 3% after IHV (p less than 0.002). It is concluded that while the hypernoea in exercise may serve as a trigger, exercise per se introduces an additional factor which serves to limit the full response seen with IHV. This attenuated response is revealed at low ventilatory levels but is masked at high levels.

Adolescent↗
PubMed1987

A non-invasive method for measuring inspiratory muscle fatigue during progressive isocapnic hyperventilation in man.

Eleven normal adults each performed a ten minute progressive isocapnic hyperventilation (PIHV) test in which ventilatory levels were increased every two minutes. All subjects exhibited mechanical fatigue by failing to maintain the target of 80% of maximum voluntary ventilation (MVV). The mean ventilation at this level was 67.5 +/- 1.4% MVV. This fatigue was accompanied by a fall in transdiaphragmatic pressure. During the test the EMG of the sternomastoid (SM) was monitored by surface electrodes and was analyzed using fast-fourier transform. The centroid frequency (Fc) fell as ventilation increased, and correlated negatively with the inability to achieve target ventilation(r = -0.99, p less than 0.015). Five subjects performed the test while the diaphragmatic EMG was recorded from an oesophageal electrode (DIes) and from surface electrodes (DIs). The Fc of DIes fell with increasing ventilation levels (r = -0.95, p less than 0.05) and there was a correlation between the Fc changes of both DIes and the SM (r = -0.92, p less than 0.001). The Fc of DIs did not correlate with either mechanical performance or the Fc of DIes, because of contamination of surface signals by signals from expiratory muscles. It is concluded that the PIHV along with surface monitoring of EMG activity from the sternomastoid can serve as a non-invasive method for evaluating inspiratory muscle fatigue.

Adult↗
PubMed1987

Lung resection for bronchiectasis in children.

Twenty children with bronchiectasis underwent pulmonary resections during an 8-year period. All patients suffered from significant symptoms that did not respond to medical treatment and had localised disease. In 7 patients bronchiectasis developed following foreign body aspiration and in two the aetiology was cystic fibrosis and immune deficiency, respectively. The lower lobes were most commonly involved. Atelectasis of the remaining ipsilateral lung was the most common postoperative complication occurring in four patients. One patient required reoperation for recurrent symptoms. Fifteen out of 18 patients who underwent curative resections were asymptomatic in the longterm follow-up. It is concluded that for children with significant symptoms due to localised bronchiectasis that fails to respond to medical treatment, resection of the affected lobes is indicated.

Adolescent↗
PubMed1987

Determinants of end expiratory volume in young children during ketamine or halothane anesthesia.

The expiratory time (Te) and the rate of lung emptying in expiration are important determinants of functional residual capacity (FRC) in infants. In order to determine whether these factors also influence FRC in children during anesthesia, 20 preschool children were studied, 10 while receiving ketamine, and 10 during halothane anesthesia. Te was measured during quiet breathing and the passive expiratory time constant (tau) was determined from the passive expiratory flow volume (V/V) curve following a brief end inspiratory airway occlusion. The number of time constants available for expiration, Te/tau, was then calculated. The difference between FRC and the relaxation volume of the respiratory system (Vrs) (FRC-Vrs) was measured by extrapolating the linear segment of the V/V curve to zero flow, and measuring FRC-Vrs. During ketamine anesthesia, tau was markedly prolonged (1.15 s, range 0.73-2.29 s), with the result that Te/tau was, in all subjects, less than 2. Children anesthetized with halothane had shorter tau (0.38 s, range 0.24-0.65 s), and Te/tau was more than 2 in most subjects. FRC-Vrs was significantly greater in the subjects from the ketamine group (203 ml, range 115-392 ml) than in those from the halothane group (32 ml, range 1-71 ml). For the 20 subjects, there was a significant relationship between FRC-Vrs (ml) and Te/tau described by the equation. FRC-Vrs = 845.0e-1.28(Te/tau) The authors conclude that, in children during ketamine anesthesia, tau is prolonged and, in these children, the relationship of Te to tau is an important determinant of FRC-Vrs. Te/tau was not related causally to FRC-Vrs in the halothane group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
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

Expiratory volume clamping: a new method to assess respiratory mechanics in sedated infants.

During breathing under sedation via a two-way valve, airflow (V), volume (delta V), and airway pressure (P) were recorded in eight normal (N) infants, seven with reversible obstructive airway disease (ROAD), and seven with chronic lung disease (CLD). Intermittently, expiratory volume clamping (EVC) was applied, involving selective occlusion of the expiratory valve for three to five breaths. The latter produced cumulative increases in delta V that, due to progressive recruitment of the Hering-Breuer reflex, were accompanied by increasing expiratory plateaus in P (i.e., apneas). The resultant passive inflation delta V-P relationships were closely approximated by the expression: delta V = aP2 + bP + c, wherein a represented the pressure-related changes in chord compliance (Crs), b the Crs at P = 0, and c the difference between the dynamic end-expiratory and relaxation volumes of the respiratory system. Relative to N, the ROAD and CLD infants had significantly reduced weight-specific values of a/kg, their b/kg values were increased, whereas the c/kg measurements did not significantly vary. Moreover, for each subject we determined the net Crs/kg obtaining at P = 20 cmH2O (i.e., Crs20/kg), an estimate of the net deflation compliance; the passive respiratory time constant (tau rs) based on the slope of the expired delta V/V relationship; and the respiratory system conductance (Grs/kg). Relative to N, the mean Crs20/kg was significantly reduced only in the infants with CLD and, due to increases in tau rs, both patient groups depicted significantly diminished values of Grs/kg, suggesting the presence of airways obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1987

Partial forced expiratory flow-volume curves in young children during ketamine anesthesia.

Maximal flows at functional residual capacity (VmaxFRC) from partial forced expiratory flow-volume (PEFV) curves were obtained in 14 normal preschool children (8 boys, 6 girls) of average age 44 mo, under general anesthesia before elective surgery. PEFV curves were generated from end inspiration by rapid compression of the chest wall with an inflatable jacket. VmaxFRC, expressed in milliliter per second, correlated linearly with height, weight, age, and FRC in milliliter and milliliters per kilogram. The best correlation of VmaxFRC (ml/s) was to height to the power of 2.47, which agrees with the results predicted by wave-speed theory. Mean FRC-corrected VmaxFRC was 2.42 +/- 0.50 (SD) FRC's/s with no significant difference between boys (2.35 FRC's/s) and girls (2.51 FRC's/s). There was no correlation between lung-size corrected VmaxFRC and height, weight, or age, but it tended to decrease with increasing FRC. The intersubject variability for VmaxFRC was reduced by normalizing for FRC, and was significantly better than that reported for awake children. This can be attributed to the greater control over volume history and more reliable maximal flow generation during anesthesia. The intrasubject coefficient of variation (CV) for VmaxFRC was 12.2%, and the intersubject CV was 20.0%. The difference may represent the variability due to dysanapsis. It is concluded that dysanapsis is not a prominent factor in children of this age group. In addition, the similarity of the regression equation for VmaxFRC vs. height to that of FRC vs. height supports the concept of equidimensional growth of the airways and lung parenchyma.

Anesthesia, General↗