Maximal inspiratory ( PImax ) and expiratory ( PEmax ) pressures were measured 7 separate times d... more Maximal inspiratory ( PImax ) and expiratory ( PEmax ) pressures were measured 7 separate times during 1 month in 40 children (13 males and 27 females, 101 to 208 months of age). After an initial period of learning, the Pimax for 20 repeated efforts was 11.1 +/- 2.4 kPa and the PEmax was 14.0 +/- 3.6 kPa. Mean values for the 20 efforts were 83% of PImax and 84% of PEmax . Individual coefficient of variation was 10% for PImax and 11% for PEmax . Postpubertal boys had higher pressures than did girls, primarily related to their greater muscle area. Pressures correlated with upper arm muscle area in both sexes and with age and height in boys. The PEmax was lower in these children than in previously reported normal adults, probably because of less muscle development. The PImax was similar to adult values, suggesting that a factor in addition to muscle strength influences inspiratory pressures in children.
The physician's ability to recognize airflow limitation was assessed in 92 stable asthmat... more The physician's ability to recognize airflow limitation was assessed in 92 stable asthmatics between seven and 12 years of age. A parental symptom score was obtained. The physician assigned a physical sign score and a clinical impression score based on the severity and lability of symptoms. Airflow limitation was considered significant if the forced expiratory flow between 25 and 75% of the vital capacity (FEF25-75) was less than 50% predicted. The FEF25-75 did not correlate with any of the scores and was less than 50% predicted in 27 of 92. There was no clinical suspicion of abnormality in 12 of 27. The FEF25-75 increased significantly after salbutamol inhalation in 22 of 23 but was persistently abnormal on follow-up in 9 of 21. We conclude that without pulmonary function tests the physician may fail to identify significant reversible airflow limitation in 13% of stable asthmatic children.
Vigorous cough was compared with complete chest physiotherapy by functional evaluation in 9 patie... more Vigorous cough was compared with complete chest physiotherapy by functional evaluation in 9 patients with cystic fibrosis who had moderate airways obstruction. Pulmonary function tests were performed before and 1 h after treatment on consecutive mornings. The time spent coughing and in sputum production were equivalent for both treatments. There were no significant differences in functional response to either treatment. Static lung volumes and flows at high lung volumes were not affected. The increases in maximal expiratory flows at 50 and 25% of the vital capacity were 14 +/- 10 SEM% and 22 +/- 11 SEM%, respectively, after cough and 18 +/- 8% and 25 +/- 13% after chest physiotherapy. These responses did not correlate with the volume of sputum produced. Because there was no clear-cut benefit of chest physiotherapy over cough alone, and the latter is easier to perform, cough is an attractive alternate method of treatment.
A three-and-a-half-month-old 2780 g critically ill infant had successful transvenous coil occlusi... more A three-and-a-half-month-old 2780 g critically ill infant had successful transvenous coil occlusion of a ductus arteriosus. At six-and-a-half months of age the infant died, and autopsy showed coverage of the coil on the aortic aspect and no lumenal narrowing. It was concluded that transvenous coil occlusion of the patent ductus arteriosus in small infants is possible and that th venous route is preferred to be arterial route.
Ventilation, breathing pattern and vagal reflexes were studied in anaesthetized (pentobarbital) n... more Ventilation, breathing pattern and vagal reflexes were studied in anaesthetized (pentobarbital) newborn rabbits aged 2-7 days before and after injection of 10 mg/kg of caffeine. With caffeine, tidal volume decreased and respiratory frequency increased but minute ventilation remained unchanged. Mean inspiratory flow increased only in the older rabbits. The breath-to-breath variability in tidal volume, mean inspiratory flow, inspiratory and expiratory times observed under control conditions was diminished in several animals following caffeine injection. Vagal pulmonary afferentation was not affected by caffeine. A facilitatory effect of caffeine on the central mechanisms controlling the breathing pattern was indicated by: (1) an enhanced Hering-Breuer expiratory-promoting reflex; (2) lack of effect on the Hering-Breuer deflation reflex; and (3) qualitatively similar effects of caffeine postvagotomy as prevagotomy.
Journal of applied physiology: respiratory, environmental and exercise physiology, 1981
The effects or airway occlusion at the end of inspiration on timing parameters and the "inte... more The effects or airway occlusion at the end of inspiration on timing parameters and the "integrated" phrenic activity were studied in 1- to 21-day-old kittens at two levels of pentobarbital anesthesia before and after bilateral vagotomy. In intact kittens during the first 2 wk of life, instead of the classical effects of airway occlusion at functional residual capacity (FRC), shortening of both inspiration and expiration, a decrease in amplitude and rate of rise of the integrated phrenic activity, or augmented breaths were recorded. These effects were not altered by an additional dose of pentobarbital sodium. In kittens of all ages, airway occlusion performed after bilateral vagotomy had no significant effects on either timing and phrenic activity. Therefore, vagally mediated reflexes are probably responsible for the paradoxical effects of airway occlusion at FRC. However, a possible contribution of the chest wall receptors cannot be excluded.
Although exertional hypercapnea has been observed in patients with advanced cystic fibrosis (CF),... more Although exertional hypercapnea has been observed in patients with advanced cystic fibrosis (CF), the causes have not been fully elucidated. In 14 patients aged 15 to 35 yr of age with advanced CF, the effects of chronic airflow limitation (CAL), increased physiologic dead space (VD), and the timing components of ventilation (VE) on gas exchange during maximal exercise were assessed. The patients were divided into those who retained CO2 during exercise, the CO2R group, and those who did not, the CO2NR group. CO2 retention was defined as a rise in end-tidal CO2 tension of 5 mm Hg or more or to a value greater than 50 mm Hg during a progressive exercise test on a cycle ergometer. CO2 retention occurred in half the subjects, usually by the halfway mark of the test, and did not rise progressively as exercise continued. It was associated with a low VE caused by a low tidal volume (VT) that was the result of a short inspiratory time to total respiratory time ratio (0.33 +/- 0.03 versus 0.38 +/- 0.04, p less than 0.02), whereas there was no difference in mean inspiratory flow or respiratory rate. Although the CO2R group had the worst CAL, with a FEV1 of 28 +/- 7 versus 41 +/- 12% predicted (p less than 0.5) and a FVC of 42 +/- 12 versus 61 +/- 9% predicted (p less than 0.01), the VT at maximal work expressed as a percentage of FVC was lower (45 +/- 13 versus 60 +/- 11, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
The relationship of abdominothoracic configuration (AT config) to maximal static inspiratory and ... more The relationship of abdominothoracic configuration (AT config) to maximal static inspiratory and expiratory mouth pressure (Pimax, Pemax) was studied in 9 children. Pmax manoeuvres were performed from the relaxed end-expiratory position (FRC relax) and after contracting the abdomen (Abd) and expanding the rib cage (RC), (FRC isovol). Anteroposterior diameters (AP) of RC and Abd during Pmax were measured with magnetometers and compared to AT config at FRC relax. During both Pimax and Pemax from FRC relax the RC AP increased and Abd AP decreased. The pressures generated did not correlate with the change in either diameter. Moving to FRC isovol prior to the onset of pressure generation had no effect on AT config obtained for Pemax, but for Pimax resulted in further increase in RC AP and decrease in Abd AP as compared to FRC relax. Despite these differences in AT config, Pimax was not significantly affected. This suggests that changes in AT config expected to place the diaphragm at a mechanical advantage were countered by an opposite effect on the other inspiratory muscles. Because the AT config for Pemax was fixed, there appears to be a unique balance of forces between the expiratory muscles acting on the rib cage and the abdomen during a maximal static expiratory effort.
Maximal static pressures (Pmax) were measured at the mouth in 119 Caucasian school children aged ... more Maximal static pressures (Pmax) were measured at the mouth in 119 Caucasian school children aged 7-13 years. Lung volumes were determined by body plethysmography. Pressures were generated near RV, at FRC and near TLC. As in adults, inspiratory Pmax decreased with increasing lung volume, whereas expiratory Pmax increased. At all lung volumes expiratory and inspiratory Pmax increased with age and were greater in males than females. Net respiratory muscle force was derived from the product of pressure and surface area (SA) over which pressure was applied. SA was estimated at different lung volumes on the basis of chest wall measurements. The dimensions obtained were utilized to calculate the SA of a truncated cone. This model was shown to be appropriate at TLC and FRC, but not RV. Since both SA and Pmax increased with age, the derived forces, as compared with pressures, proportionally increased more with age. Thus changes in Pmax underestimated changes in force during growth.
The relationship between the growth of lung volumes and the development of maximal static pressur... more The relationship between the growth of lung volumes and the development of maximal static pressures was examined in a 1 year follow-up study of 17 female swimmers, initially less than 12 years of age. Lung volumes were measured by body plethysmography, and maximal static inspiratory and expiratory pressures were generated near residual volume, at functional residual capacity and near total lung capacity (TLC). The results were compared to the regressions obtained from cross-sectional data generated on 59 girls randomly selected from a local school. Height was similar in swimmers and controls. Vital capacity and total lung capacity increased during the year to exceed normal limits in 11 of 17 swimmers. The only significant increase of maximal static pressures during 1 year occurred in expiration near TLC in those swimmers initially less than 10 years of age, and all pressures fell within normal limits. We conclude that large lung volumes in swimmers cannot be accounted for by an increased ability to inflate and deflate the lung by the respiratory muscles.
The objective of this study was to document that an observational study decreases the use of the ... more The objective of this study was to document that an observational study decreases the use of the emergency department (ED) for asthma. Comparison of rates between an audit and prospective period were used at a regional referral pediatric hospital ED. A total of 526 asthma visits from February 12, 1992, to April 10, 1992, were examined in an initial audit and compared to 725 visits during a prospective study from May 16, 1993, to September 29, 1993. A physician check list for medications and follow-up plans was utilized during the prospective study. The rate of repeat visits and admissions was compared between the audit and the prospective periods. In the audit, 422 asthma patients were seen, and there were 68 repeat visits within one week of the initial visit and 153 admissions. For 29 of the 68 repeat visits there was no documentation that medication had been increased after the initial visit. No follow-up plans were recorded in 275 of the 526 visits. During the prospective period 668 children presented to the ED with asthma, and 346 were enrolled into the study on risks for repeat visits. There were 57 repeat visits and 89 admissions. The repeat visit rate during the prospective period was 9 and 8%, respectively, in the enrolled and nonenrolled subjects. The repeat visit and admission rate decreased during the prospective period as compared to during the audit by 39% (P = 0.004) and 58% (P < 0.0001), respectively. A possible explanation for the difference in admission and repeat visit rates between the audit and prospective study is that physicians' behavior may have been altered by the awareness that their behavior was being closely monitored during the study.
Abnormalities in control of breathing have been associated with near-miss sudden infant death syn... more Abnormalities in control of breathing have been associated with near-miss sudden infant death syndrome. Because caffeine is a respiratory stimulant, its effect on breathing pattern was evaluated in 12 infants with infantile apnea. Caffeine induced a significant increase in ventilation, tidal volume, and mean inspiratory flow. In contrast, no changes were noted in inspiratory time, expiratory time, or total cycle duration. These effects were observed with plasma concentrations of caffeine ranging from 8 to 20 mg/L. Caffeine increases ventilation mainly by increasing central inspiratory drive, and not be effective timing (T1/TTOT). This drug may be of value in near-miss SIDS.
The effect of nocturnal oxygen therapy on mortality and morbidity rates and on progression of dis... more The effect of nocturnal oxygen therapy on mortality and morbidity rates and on progression of disease was tested in a double-blind, randomized trial of 28 subjects with advanced cystic fibrosis. Patients were selected on the basis that their awake arterial oxygen tension was less than 65 mm Hg when they were clinically stable. Oxygen was prescribed in 1 L/min increments to obtain an awake arterial oxygen tension of greater than or equal to 70 mm Hg. Subjects received humidified oxygen or room air from modified concentrators. They were enrolled over a 3-year period and followed for an average (+/- SD) of 26 +/- 9 months. The average number of hours per night of concentrator use was 5.3 +/- 3.2 hours in the air group and 7.0 +/- 1.9 hours in the oxygen group. Over the follow-up period there were four deaths in each group, and oxygen therapy had no significant effect on the frequency of hospitalizations. Progression of disease was ascertained from nutritional status, pulmonary function, blood gas values, exercise ability, and right ventricular ejection fraction response to exercise (as measured by equilibrium-gated radionuclide angiocardiography), and psychologic status was measured by standardized tests of mood, self-esteem, and cognitive function; group comparisons for the first year revealed no significant differences; however, school or work attendance was maintained in the oxygen group but deteriorated in the air group. Clinical signs of cor pulmonale were documented during follow-up in 10 patients in toto, and all lived at least 9 months from the onset of these signs. The lack of association between the onset of these signs and imminent death, or the usefulness of measurements of the maximal oxygen uptake during progressive exercise and the right ventricular ejection fraction response to exercise as prognostic indicators, suggest that death may not be the result of cor pulmonale. We conclude that nocturnal oxygen treatment in patients with cystic fibrosis did not appear to affect mortality rates, the frequency of hospitalizations, or the progression of disease; oxygen use should be instituted only after the development of symptoms related to hypoxemia.
Journal of Pediatric Gastroenterology and Nutrition, 1988
We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug... more We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug, who had no clinical or biochemical evidence of pancreatic insufficiency during infancy. They underwent pancreatic secretory function testing at 11 and 9 months of age, respectively. Both patients had sufficient lipase and colipase secretion to maintain normal digestion of fat, confirming that meconium disease in CF does not necessarily imply pancreatic insufficiency and the need for enzyme supplementation in infancy. Nonetheless, we documented markedly reduced enzyme secretion in both patients, implying a potential role for the pancreas in the pathogenesis of meconium disease, even when clinical pancreatic insufficiency is absent. In addition, our patient with meconium ileus had a severely limited fluid secretory capacity (10.3% of mean normal values). In contrast, the patient with the milder presentation of meconium plug had a far greater ability to secrete fluid (75% of mean normal), but had poorer pancreatic proteolytic activity. We suggest that impaired fluid secretion may be a very significant factor in the pathogenesis of meconium ileus, and we speculate that an inability to maintain sufficient intraluminal fluid relative to the degree of pancreatic proteolytic deficiency may more adequately explain the risk of occurrence and the severity of intestinal obstruction in CF than either factor alone.
... Pulmonary Complications After Congenital Heart Surgery Fiona Healy 1 , Brian D. Hanna 2 and R... more ... Pulmonary Complications After Congenital Heart Surgery Fiona Healy 1 , Brian D. Hanna 2 and Raezelle Zinman *,1 ... Koga et al. demonstrated significant clinical improvement with the use of HFCWO in a patient with acute respiratory distress from plastic bronchitis [82]. ...
Archives of Pediatrics & Adolescent Medicine, 1995
To identify risk factors predictive of sunscreen use in children. Cross-sectional review of conve... more To identify risk factors predictive of sunscreen use in children. Cross-sectional review of convenience sample. Emergency department of a regional referral pediatric hospital. Nine hundred twenty-five parents of children presenting to the emergency department in August 1993. Parental risk factors assessed were use of sunscreen, tanning behaviors, previous blistering sunburn, knowledge of cancer risk related to sunburn and sun protection factor definition, education level, and other health-promoting behaviors. The parents were asked about perceived risk for their child's being sunburned in the next month or development of skin cancer in their lifetime, as well as an estimation of safe sun exposure time for their child. Child risk factors included a history of previous painful sunburn and parental assessment of their child's skin type based on susceptibility to sunburn. Eighty-four percent of parents reported that their children had used sunscreen at least once in the previous 2 months. The use of sunscreen in children younger than 1 year was 54%, from 1 to 12 years of age was 91%, and older than 12 years was 68%. Factors associated with increased likelihood of sunscreen use were age of 1 to 12 years, parental use of sunscreen, estimation of safe sun exposure of less than 30 minutes, description of child skin type as burns "sometimes," "easily," or "always," and correct definition of sun protection factor. Application of a multivariate model yielded a sensitivity of 96%, specificity of 36%, and positive predictive value of sunscreen use of 89%. Sunscreen use in parents is predictive of use in their children and relates more to experience with sunburn than with concerns about future skin cancer risk.
Maximal inspiratory ( PImax ) and expiratory ( PEmax ) pressures were measured 7 separate times d... more Maximal inspiratory ( PImax ) and expiratory ( PEmax ) pressures were measured 7 separate times during 1 month in 40 children (13 males and 27 females, 101 to 208 months of age). After an initial period of learning, the Pimax for 20 repeated efforts was 11.1 +/- 2.4 kPa and the PEmax was 14.0 +/- 3.6 kPa. Mean values for the 20 efforts were 83% of PImax and 84% of PEmax . Individual coefficient of variation was 10% for PImax and 11% for PEmax . Postpubertal boys had higher pressures than did girls, primarily related to their greater muscle area. Pressures correlated with upper arm muscle area in both sexes and with age and height in boys. The PEmax was lower in these children than in previously reported normal adults, probably because of less muscle development. The PImax was similar to adult values, suggesting that a factor in addition to muscle strength influences inspiratory pressures in children.
The physician's ability to recognize airflow limitation was assessed in 92 stable asthmat... more The physician's ability to recognize airflow limitation was assessed in 92 stable asthmatics between seven and 12 years of age. A parental symptom score was obtained. The physician assigned a physical sign score and a clinical impression score based on the severity and lability of symptoms. Airflow limitation was considered significant if the forced expiratory flow between 25 and 75% of the vital capacity (FEF25-75) was less than 50% predicted. The FEF25-75 did not correlate with any of the scores and was less than 50% predicted in 27 of 92. There was no clinical suspicion of abnormality in 12 of 27. The FEF25-75 increased significantly after salbutamol inhalation in 22 of 23 but was persistently abnormal on follow-up in 9 of 21. We conclude that without pulmonary function tests the physician may fail to identify significant reversible airflow limitation in 13% of stable asthmatic children.
Vigorous cough was compared with complete chest physiotherapy by functional evaluation in 9 patie... more Vigorous cough was compared with complete chest physiotherapy by functional evaluation in 9 patients with cystic fibrosis who had moderate airways obstruction. Pulmonary function tests were performed before and 1 h after treatment on consecutive mornings. The time spent coughing and in sputum production were equivalent for both treatments. There were no significant differences in functional response to either treatment. Static lung volumes and flows at high lung volumes were not affected. The increases in maximal expiratory flows at 50 and 25% of the vital capacity were 14 +/- 10 SEM% and 22 +/- 11 SEM%, respectively, after cough and 18 +/- 8% and 25 +/- 13% after chest physiotherapy. These responses did not correlate with the volume of sputum produced. Because there was no clear-cut benefit of chest physiotherapy over cough alone, and the latter is easier to perform, cough is an attractive alternate method of treatment.
A three-and-a-half-month-old 2780 g critically ill infant had successful transvenous coil occlusi... more A three-and-a-half-month-old 2780 g critically ill infant had successful transvenous coil occlusion of a ductus arteriosus. At six-and-a-half months of age the infant died, and autopsy showed coverage of the coil on the aortic aspect and no lumenal narrowing. It was concluded that transvenous coil occlusion of the patent ductus arteriosus in small infants is possible and that th venous route is preferred to be arterial route.
Ventilation, breathing pattern and vagal reflexes were studied in anaesthetized (pentobarbital) n... more Ventilation, breathing pattern and vagal reflexes were studied in anaesthetized (pentobarbital) newborn rabbits aged 2-7 days before and after injection of 10 mg/kg of caffeine. With caffeine, tidal volume decreased and respiratory frequency increased but minute ventilation remained unchanged. Mean inspiratory flow increased only in the older rabbits. The breath-to-breath variability in tidal volume, mean inspiratory flow, inspiratory and expiratory times observed under control conditions was diminished in several animals following caffeine injection. Vagal pulmonary afferentation was not affected by caffeine. A facilitatory effect of caffeine on the central mechanisms controlling the breathing pattern was indicated by: (1) an enhanced Hering-Breuer expiratory-promoting reflex; (2) lack of effect on the Hering-Breuer deflation reflex; and (3) qualitatively similar effects of caffeine postvagotomy as prevagotomy.
Journal of applied physiology: respiratory, environmental and exercise physiology, 1981
The effects or airway occlusion at the end of inspiration on timing parameters and the "inte... more The effects or airway occlusion at the end of inspiration on timing parameters and the "integrated" phrenic activity were studied in 1- to 21-day-old kittens at two levels of pentobarbital anesthesia before and after bilateral vagotomy. In intact kittens during the first 2 wk of life, instead of the classical effects of airway occlusion at functional residual capacity (FRC), shortening of both inspiration and expiration, a decrease in amplitude and rate of rise of the integrated phrenic activity, or augmented breaths were recorded. These effects were not altered by an additional dose of pentobarbital sodium. In kittens of all ages, airway occlusion performed after bilateral vagotomy had no significant effects on either timing and phrenic activity. Therefore, vagally mediated reflexes are probably responsible for the paradoxical effects of airway occlusion at FRC. However, a possible contribution of the chest wall receptors cannot be excluded.
Although exertional hypercapnea has been observed in patients with advanced cystic fibrosis (CF),... more Although exertional hypercapnea has been observed in patients with advanced cystic fibrosis (CF), the causes have not been fully elucidated. In 14 patients aged 15 to 35 yr of age with advanced CF, the effects of chronic airflow limitation (CAL), increased physiologic dead space (VD), and the timing components of ventilation (VE) on gas exchange during maximal exercise were assessed. The patients were divided into those who retained CO2 during exercise, the CO2R group, and those who did not, the CO2NR group. CO2 retention was defined as a rise in end-tidal CO2 tension of 5 mm Hg or more or to a value greater than 50 mm Hg during a progressive exercise test on a cycle ergometer. CO2 retention occurred in half the subjects, usually by the halfway mark of the test, and did not rise progressively as exercise continued. It was associated with a low VE caused by a low tidal volume (VT) that was the result of a short inspiratory time to total respiratory time ratio (0.33 +/- 0.03 versus 0.38 +/- 0.04, p less than 0.02), whereas there was no difference in mean inspiratory flow or respiratory rate. Although the CO2R group had the worst CAL, with a FEV1 of 28 +/- 7 versus 41 +/- 12% predicted (p less than 0.5) and a FVC of 42 +/- 12 versus 61 +/- 9% predicted (p less than 0.01), the VT at maximal work expressed as a percentage of FVC was lower (45 +/- 13 versus 60 +/- 11, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
The relationship of abdominothoracic configuration (AT config) to maximal static inspiratory and ... more The relationship of abdominothoracic configuration (AT config) to maximal static inspiratory and expiratory mouth pressure (Pimax, Pemax) was studied in 9 children. Pmax manoeuvres were performed from the relaxed end-expiratory position (FRC relax) and after contracting the abdomen (Abd) and expanding the rib cage (RC), (FRC isovol). Anteroposterior diameters (AP) of RC and Abd during Pmax were measured with magnetometers and compared to AT config at FRC relax. During both Pimax and Pemax from FRC relax the RC AP increased and Abd AP decreased. The pressures generated did not correlate with the change in either diameter. Moving to FRC isovol prior to the onset of pressure generation had no effect on AT config obtained for Pemax, but for Pimax resulted in further increase in RC AP and decrease in Abd AP as compared to FRC relax. Despite these differences in AT config, Pimax was not significantly affected. This suggests that changes in AT config expected to place the diaphragm at a mechanical advantage were countered by an opposite effect on the other inspiratory muscles. Because the AT config for Pemax was fixed, there appears to be a unique balance of forces between the expiratory muscles acting on the rib cage and the abdomen during a maximal static expiratory effort.
Maximal static pressures (Pmax) were measured at the mouth in 119 Caucasian school children aged ... more Maximal static pressures (Pmax) were measured at the mouth in 119 Caucasian school children aged 7-13 years. Lung volumes were determined by body plethysmography. Pressures were generated near RV, at FRC and near TLC. As in adults, inspiratory Pmax decreased with increasing lung volume, whereas expiratory Pmax increased. At all lung volumes expiratory and inspiratory Pmax increased with age and were greater in males than females. Net respiratory muscle force was derived from the product of pressure and surface area (SA) over which pressure was applied. SA was estimated at different lung volumes on the basis of chest wall measurements. The dimensions obtained were utilized to calculate the SA of a truncated cone. This model was shown to be appropriate at TLC and FRC, but not RV. Since both SA and Pmax increased with age, the derived forces, as compared with pressures, proportionally increased more with age. Thus changes in Pmax underestimated changes in force during growth.
The relationship between the growth of lung volumes and the development of maximal static pressur... more The relationship between the growth of lung volumes and the development of maximal static pressures was examined in a 1 year follow-up study of 17 female swimmers, initially less than 12 years of age. Lung volumes were measured by body plethysmography, and maximal static inspiratory and expiratory pressures were generated near residual volume, at functional residual capacity and near total lung capacity (TLC). The results were compared to the regressions obtained from cross-sectional data generated on 59 girls randomly selected from a local school. Height was similar in swimmers and controls. Vital capacity and total lung capacity increased during the year to exceed normal limits in 11 of 17 swimmers. The only significant increase of maximal static pressures during 1 year occurred in expiration near TLC in those swimmers initially less than 10 years of age, and all pressures fell within normal limits. We conclude that large lung volumes in swimmers cannot be accounted for by an increased ability to inflate and deflate the lung by the respiratory muscles.
The objective of this study was to document that an observational study decreases the use of the ... more The objective of this study was to document that an observational study decreases the use of the emergency department (ED) for asthma. Comparison of rates between an audit and prospective period were used at a regional referral pediatric hospital ED. A total of 526 asthma visits from February 12, 1992, to April 10, 1992, were examined in an initial audit and compared to 725 visits during a prospective study from May 16, 1993, to September 29, 1993. A physician check list for medications and follow-up plans was utilized during the prospective study. The rate of repeat visits and admissions was compared between the audit and the prospective periods. In the audit, 422 asthma patients were seen, and there were 68 repeat visits within one week of the initial visit and 153 admissions. For 29 of the 68 repeat visits there was no documentation that medication had been increased after the initial visit. No follow-up plans were recorded in 275 of the 526 visits. During the prospective period 668 children presented to the ED with asthma, and 346 were enrolled into the study on risks for repeat visits. There were 57 repeat visits and 89 admissions. The repeat visit rate during the prospective period was 9 and 8%, respectively, in the enrolled and nonenrolled subjects. The repeat visit and admission rate decreased during the prospective period as compared to during the audit by 39% (P = 0.004) and 58% (P < 0.0001), respectively. A possible explanation for the difference in admission and repeat visit rates between the audit and prospective study is that physicians' behavior may have been altered by the awareness that their behavior was being closely monitored during the study.
Abnormalities in control of breathing have been associated with near-miss sudden infant death syn... more Abnormalities in control of breathing have been associated with near-miss sudden infant death syndrome. Because caffeine is a respiratory stimulant, its effect on breathing pattern was evaluated in 12 infants with infantile apnea. Caffeine induced a significant increase in ventilation, tidal volume, and mean inspiratory flow. In contrast, no changes were noted in inspiratory time, expiratory time, or total cycle duration. These effects were observed with plasma concentrations of caffeine ranging from 8 to 20 mg/L. Caffeine increases ventilation mainly by increasing central inspiratory drive, and not be effective timing (T1/TTOT). This drug may be of value in near-miss SIDS.
The effect of nocturnal oxygen therapy on mortality and morbidity rates and on progression of dis... more The effect of nocturnal oxygen therapy on mortality and morbidity rates and on progression of disease was tested in a double-blind, randomized trial of 28 subjects with advanced cystic fibrosis. Patients were selected on the basis that their awake arterial oxygen tension was less than 65 mm Hg when they were clinically stable. Oxygen was prescribed in 1 L/min increments to obtain an awake arterial oxygen tension of greater than or equal to 70 mm Hg. Subjects received humidified oxygen or room air from modified concentrators. They were enrolled over a 3-year period and followed for an average (+/- SD) of 26 +/- 9 months. The average number of hours per night of concentrator use was 5.3 +/- 3.2 hours in the air group and 7.0 +/- 1.9 hours in the oxygen group. Over the follow-up period there were four deaths in each group, and oxygen therapy had no significant effect on the frequency of hospitalizations. Progression of disease was ascertained from nutritional status, pulmonary function, blood gas values, exercise ability, and right ventricular ejection fraction response to exercise (as measured by equilibrium-gated radionuclide angiocardiography), and psychologic status was measured by standardized tests of mood, self-esteem, and cognitive function; group comparisons for the first year revealed no significant differences; however, school or work attendance was maintained in the oxygen group but deteriorated in the air group. Clinical signs of cor pulmonale were documented during follow-up in 10 patients in toto, and all lived at least 9 months from the onset of these signs. The lack of association between the onset of these signs and imminent death, or the usefulness of measurements of the maximal oxygen uptake during progressive exercise and the right ventricular ejection fraction response to exercise as prognostic indicators, suggest that death may not be the result of cor pulmonale. We conclude that nocturnal oxygen treatment in patients with cystic fibrosis did not appear to affect mortality rates, the frequency of hospitalizations, or the progression of disease; oxygen use should be instituted only after the development of symptoms related to hypoxemia.
Journal of Pediatric Gastroenterology and Nutrition, 1988
We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug... more We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug, who had no clinical or biochemical evidence of pancreatic insufficiency during infancy. They underwent pancreatic secretory function testing at 11 and 9 months of age, respectively. Both patients had sufficient lipase and colipase secretion to maintain normal digestion of fat, confirming that meconium disease in CF does not necessarily imply pancreatic insufficiency and the need for enzyme supplementation in infancy. Nonetheless, we documented markedly reduced enzyme secretion in both patients, implying a potential role for the pancreas in the pathogenesis of meconium disease, even when clinical pancreatic insufficiency is absent. In addition, our patient with meconium ileus had a severely limited fluid secretory capacity (10.3% of mean normal values). In contrast, the patient with the milder presentation of meconium plug had a far greater ability to secrete fluid (75% of mean normal), but had poorer pancreatic proteolytic activity. We suggest that impaired fluid secretion may be a very significant factor in the pathogenesis of meconium ileus, and we speculate that an inability to maintain sufficient intraluminal fluid relative to the degree of pancreatic proteolytic deficiency may more adequately explain the risk of occurrence and the severity of intestinal obstruction in CF than either factor alone.
... Pulmonary Complications After Congenital Heart Surgery Fiona Healy 1 , Brian D. Hanna 2 and R... more ... Pulmonary Complications After Congenital Heart Surgery Fiona Healy 1 , Brian D. Hanna 2 and Raezelle Zinman *,1 ... Koga et al. demonstrated significant clinical improvement with the use of HFCWO in a patient with acute respiratory distress from plastic bronchitis [82]. ...
Archives of Pediatrics & Adolescent Medicine, 1995
To identify risk factors predictive of sunscreen use in children. Cross-sectional review of conve... more To identify risk factors predictive of sunscreen use in children. Cross-sectional review of convenience sample. Emergency department of a regional referral pediatric hospital. Nine hundred twenty-five parents of children presenting to the emergency department in August 1993. Parental risk factors assessed were use of sunscreen, tanning behaviors, previous blistering sunburn, knowledge of cancer risk related to sunburn and sun protection factor definition, education level, and other health-promoting behaviors. The parents were asked about perceived risk for their child's being sunburned in the next month or development of skin cancer in their lifetime, as well as an estimation of safe sun exposure time for their child. Child risk factors included a history of previous painful sunburn and parental assessment of their child's skin type based on susceptibility to sunburn. Eighty-four percent of parents reported that their children had used sunscreen at least once in the previous 2 months. The use of sunscreen in children younger than 1 year was 54%, from 1 to 12 years of age was 91%, and older than 12 years was 68%. Factors associated with increased likelihood of sunscreen use were age of 1 to 12 years, parental use of sunscreen, estimation of safe sun exposure of less than 30 minutes, description of child skin type as burns "sometimes," "easily," or "always," and correct definition of sun protection factor. Application of a multivariate model yielded a sensitivity of 96%, specificity of 36%, and positive predictive value of sunscreen use of 89%. Sunscreen use in parents is predictive of use in their children and relates more to experience with sunburn than with concerns about future skin cancer risk.
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