Biomedical subjects

W C Hop

Publications and source records attributed to W C Hop.

At least 37 records · Page 2Linked to original sources

PubMed2001

Erectile and ejaculatory dysfunction in a community-based sample of men 50 to 78 years old: prevalence, concern, and relation to sexual activity.

OBJECTIVES: To determine the prevalence rates of erectile and ejaculatory dysfunction, associated bother, and their relation to sexual activity in a population-based sample of elderly men.Methods. Data were collected from 1688 men by way of self-administered questionnaires (including the International Continence Society male sex questionnaire) and measurements at a health center and urology outpatient department. RESULTS: The prevalence of significant erectile dysfunction (ie, erections of severely reduced rigidity or no erections) increased from 3% in men 50 to 54 years old to 26% in men 70 to 78 years old. In the same age strata, the prevalence of significant ejaculatory dysfunction (ie, ejaculations with significantly reduced volume or no ejaculations) increased from 3% to 35%. Pain or discomfort during ejaculation was rare (1%) and independent of age. In general, men were more concerned about erectile dysfunction than about ejaculatory dysfunction. However, most men had no or only little concern about their dysfunction. The percentage of men who reported being sexually active declined with increasing age and was lower in men with erectile and ejaculatory dysfunction and in men without a partner. In sexually active men, 17% to 28% had no normal erections, indicating that with advancing age normal erections are not an absolute prerequisite for a sexually active life. CONCLUSIONS: Erectile and ejaculatory dysfunction are common in elderly men. The results of this study indicate that these conditions are much less of a problem for older men than previously suggested.

Age Distribution↗

PubMed2001

The prognostic value of histology in the assessment of patients with Budd-Chiari syndrome.

BACKGROUND/AIMS: It is unclear whether treatment of patients with Budd-Chiari syndrome (BCS) should be based on liver histology, as large histopathological studies have not been performed. We investigated the relationship between the histopathological findings and survival. METHODS: We studied the clinical features and findings on biopsy specimens in 45 patients with BCS who were admitted to four tertiary referral medical centers. Histological findings, i.e. congestion, necrosis, inflammation and fibrosis, were graded. Survival was assessed in relation to histological findings and clinical features at the time of diagnosis as well as in relation to subsequent treatment with or without portosystemic shunting. RESULTS: Centrilobular congestion, centrilobular necrosis, lobular inflammation and portal inflammation were not significantly related to survival. In addition, there was no association between either pericentral or periportal fibrosis and survival. Univariate analysis revealed that the prothrombin time and Child-Pugh score were significantly related to survival (P = 0.005 and Ptrend = 0.02, respectively). Multivariate analysis yielded the Child-Pugh score, serum alanine aminotransferase (ALT) and treatment with portosystemic shunting as independent prognostic indicators. CONCLUSIONS: We found no evidence for a relationship between early liver pathology and survival. Child-Pugh score, serum ALT and portosystemic shunting appeared to be prognostic indicators for patients with BCS.

Adolescent↗

PubMed2001

In vitro cytokine production of TNFalpha and IL-13 correlates with acute liver transplant rejection.

Individuals may differ in their capacity to produce cytokines. Since cytokines play a key role in allograft rejection, we investigated whether inter-individual differences in cytokine production by in vitro stimulated PBMC are related to the occurrence of acute liver transplant rejection. Our study group comprised 49 liver transplant recipients and 30 healthy individuals. Rejection, which occurred within one month after liver transplantation, was defined in 22 patients ("rejectors") as biopsy-proven rejection, treated with high dose prednisolone. Patients who never experienced rejection episodes were termed as "nonrejectors" (n=27). PBMC of healthy individuals and of liver transplant recipients, collected late after transplantation (mean 3.5 years), were cultured in the presence and absence of Concanavalin A. The production of TNF-alpha, IFN-gamma, IL-10, and IL-13 was measured in supernatant after 1, 2, 3, 4, and 7 days of cell culture. In cell culture, stimulated PBMC of rejectors were found to produce significantly higher levels of TNF-alpha, while there was a trend towards higher production of IFN-gamma and IL-10 as compared to nonrejectors. After grouping patients into high or low cytokine producers based upon reference levels of the healthy individuals using multivariate analysis it was found that occurrence of acute liver transplant rejection correlated to high production of TNF-alpha and low production of IL-13. After stimulated cell culture PBMC of liver transplant recipients show a differential production of TNF-alpha and IL-13 which is correlated with the occurrence of acute liver transplant rejection.

Acute Disease↗

PubMed2001

Dynamics of immunoreactive endothelin plasma levels during ovarian stimulation for in vitro fertilization with and without dietary sodium restriction.

OBJECTIVE: To investigate the correlation between immunoreactive endothelin plasma levels and both the number and size of follicles and its relationship with the development of ovarian hyperstimulation syndrome, in in vitro fertilization cycles, with and without dietary sodium restriction. STUDY DESIGN: Randomized study in an assisted reproduction unit of a large teaching hospital. Data of 88 women form the basis of this report (45 ad libitum sodium intake and 43 dietary sodium restriction). Non-parametric tests were used for statistical analysis. RESULTS: Immunoreactive endothelin plasma levels neither correlate with the number of follicles, independent of their size, nor with the grade of ovarian hyperstimulation syndrome. Immunoreactive endothelin plasma levels decrease significantly in the luteal phase. These results are the same in both sodium diet groups. CONCLUSIONS: Immunoreactive endothelin plasma levels do not correlate with the number and size of follicles and they are not related to the development of ovarian hyperstimulation syndrome. These findings are independent of sodium intake.

Diet, Sodium-Restricted↗

PubMed2001

Randomized study comparing cardiac response in endovascular and open abdominal aortic aneurysm repair.

BACKGROUND: The aim was to compare the cardiac response and the incidence of adverse cardiac events during and after endovascular (EVAR) and open (OR) repair of abdominal aortic aneurysms (AAAs). METHODS: Seventy-six patients with an AAA suitable for EVAR, and in a general condition allowing open surgery were randomized to EVAR (57 patients) or OR (19 patients). The analysis was on an intention-to-treat basis. Haemodynamic variables were assessed intraoperatively before, during and after aortic occlusion. During the procedure myocardial ischaemia was identified with use of electrocardiography (ECG) and transoesophageal echocardiography (TEE). After operation, cardiac complications were diagnosed by clinical observation, 12-lead ECG at 1 h, 1 day and 7 days, echocardiography at 1 month and measurement of cardiac enzymes. RESULTS: After aortic occlusion, a greater decrease in systemic vascular resistance compared with baseline was observed with OR than with EVAR (- 396 and - 70 dyne s/cm5 respectively; P = 0.03). The stroke work index, as a direct measure of myocardial performance, demonstrated a decrease during OR and an increase during EVAR during aortic occlusion (- 6.6 and + 1.7 g m/m2 respectively; P = 0.03) as well as after aortic occlusion (- 7.6 and + 3.4 g m/m2 respectively; P < 0.01), compared with baseline. The incidence of postoperative clinical cardiac complications was comparable in the two study groups; however, myocardial ischaemia, as observed by ECG and TEE, was observed more frequently in the OR group (ten of 19 versus 15 of 57 patients; P = 0.05). CONCLUSION: Haemodynamic changes were less severe and there was a lower incidence of myocardial ischaemia during EVAR than during OR. Studies are needed to demonstrate whether this may reduce the operative mortality rate.

Aged↗

PubMed2001

'Pseudo-aldosteronism' induced by intravenous glycyrrhizin treatment of chronic hepatitis C patients.

BACKGROUND AND AIMS: Treatment with intravenous glycyrrhizin reduces the progression of liver disease caused by chronic hepatitis C (HCV) infection. Glycyrrhetinic acid, a metabolite of glycyrrhizin, inhibits the renal conversion of cortisol to cortisone by inhibiting the enzyme 11 beta-hydroxysteroiddehydrogenase in the kidney. The resulting excess of cortisol subsequently stimulates the mineralocorticoid receptor, leading to pseudo-aldosteronism with hypertension, hypokalemia and eventually renin and aldosterone suppression. The aim of this study was to evaluate the occurrence of pseudo-aldosteronism after treatment of chronic hepatitis C (HCV) patients with increasing doses of intravenous glycyrrhizin. METHODS: Forty-four HCV patients with chronic hepatitis or compensated cirrhosis were treated with intravenous glycyrrhizin 6 x 200 mg/week, 3 x 240 mg/week or 3 x 0 mg/week (placebo) for 4 weeks. In all patients, bodyweight, blood pressure and plasma concentrations of sodium, potassium, cortisol, DHEA-S (dehydroepiandrosterone sulfate), renin and aldosterone were measured before, and at 0 and 4 weeks after treatment. RESULTS: Within the placebo group, no significant changes were observed. Within the 1200 mg group systolic blood pressure was significantly higher at the end of treatment, while aldosterone was significantly lower; at the end of the follow-up period these values had returned to baseline. The changes from baseline in systolic and diastolic blood pressure at the end of treatment were significantly higher in the 1200 mg group compared to the placebo group. The changes in aldosterone and potassium concentrations at the end of treatment increased with increasing dosage, although not significantly. CONCLUSION: Hepatitis C virus patients with chronic hepatitis or compensated cirrhosis show minor reversible symptoms of pseudo-aldosteronism after treatment with 1200 mg glycyrrhizin weekly for 4 weeks.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed2001

A comparison of distal end-to-side and end-to-end anastomoses in femoropopliteal bypasses.

OBJECTIVES: to compare end-to-side (ETS) and end-to-end (ETE) distal anastomoses. Design retrospective cohort study. METHODS: retrospective cohort study. Between 1988 and 1992, 204 femoropopliteal bypasses (188 patients) were performed for claudication (55%), rest pain (22%) and tissue loss (23%). One hundred and eighteen ETS were compared with 86 ETE in terms of patency or a mean (range) follow-up of 68 (0.5-120) months. RESULTS: overall patency was 86%, 66% and 57% at 1, 5 and 8 years, respectively. Multivariate analysis showed ETE anastomoses (p =0.04), and also knee bypass ( p =0.05) and venous conduit ( p =0.004) to be significantly associated with impaired patency. CONCLUSIONS: ETE may improve femoropopliteal bypass patency.

Anastomosis, Surgical↗

PubMed2001

Pharmacokinetics and metabolism of intravenous midazolam in preterm infants.

BACKGROUND: Midazolam, a benzodiazepine, is finding expanded use in neonatal intensive care units. We studied the pharmacokinetics and metabolism of midazolam after a single intravenous dose in preterm infants. METHODS: The pharmacokinetics of midazolam and its hydroxylated metabolite (1-OH-midazolam) after a single 0.1 mg/kg intravenous dose of midazolam were determined in 24 preterm infants (gestational age, 26 to 34 weeks; postnatal age, 3 to 11 days). Blood samples were obtained before drug administration and at 0.5, 1, 2, 4, 6, 12, and 24 hours after the start of the infusion. Midazolam and 1-OH-midazolam concentrations were determined by use of gas chromatography-mass spectrometry. RESULTS: Total body clearance, apparent volume of distribution, and plasma half-life of midazolam were (median [range]): 1.8 (0.7-6.7) ml/kg per min, 1.1 (0.4-4.2) L/kg, and 6.3 (2.6-17.7) h, respectively. In 19 of 24 preterm infants, 1-OH-midazolam concentrations could be detected: 1-OH-midazolam (1-OH-M) maximal concentration of drug in plasma (C(max)), time to reach C(max) (T(max)), and 1-OH-M/M area under the concentration-time curve from time zero to the last sampling time point (AUC(0-t)) ratio were [median (range)]: 8.2 (<0.5-68.2) ng/ml, 6 (1-12) h, and 0.09 (<0.001-1), respectively. Midazolam plasma clearance was increased in those infants who had indomethacin (INN, indometacin) exposure. DISCUSSION: Consequent to immature hepatic cytochrome P450 3A4 (CYP3A4) activity, midazolam clearance and 1-OH-midazolam concentrations are reduced markedly in preterm infants as compared to concentrations in previous reports from studies in older children and adults. Indomethacin exposure and its apparent impact on midazolam clearance support alteration of drug disposition produced by a patent ductus arteriosus or by the direct effects of indomethacin on hemodynamic or renal function.

Anti-Anxiety Agents↗

PubMed2001

A comparison of 3 types of covered metal stents for the palliation of patients with dysphagia caused by esophagogastric carcinoma: a prospective, randomized study.

BACKGROUND: There are currently 3 types of covered metal stents available in Europe for palliation of patients with malignant dysphagia. Their relative merits have not been compared in a prospective, randomized study. METHODS: One hundred consecutive patients with esophagogastric carcinoma were randomized to placement of an Ultraflex stent, a Flamingo Wallstent, or a Gianturco-Z stent. Malignant strictures of the esophagus were treated by insertion of a small-diameter stent (n = 71), whereas those involving the gastric cardia were treated with a large-diameter stent (n = 29). RESULTS: At 4 weeks, dysphagia had improved in all patient groups (p < 0.001), but the degree of improvement did not differ among the 3 groups (p = 0.14). There were differences among the 3 stent types with respect to major complications (Ultraflex stent: 8/34 [24%], Flamingo Wallstent: 6/33 [18%], and Gianturco-Z stent: 12/33 [36%]), but these were not statistically significant (p = 0.23). Nine patients (26%) with an Ultraflex stent, 11 (33%) with a Flamingo Wallstent, and 8 (24%) with a Gianturco-Z stent had recurrent dysphagia (p = 0.73), mainly because of tumor overgrowth or stent migration; 12 of 13 episodes of migration involved small-diameter stents in the esophagus. CONCLUSIONS: All 3 covered metal stents evaluated offer the same degree of palliation of patients with malignant dysphagia. Placement of Gianturco-Z stents was associated with more complications as compared with Ultraflex stents and Flamingo Wallstents. Although stent migration is reduced by increasing stent diameter, tumor overgrowth remains an intractable problem that requires a new approach.

Aged↗

PubMed2001

Hormonal and metabolic stress responses after major surgery in children aged 0-3 years: a double-blind, randomized trial comparing the effects of continuous versus intermittent morphine.

Children aged 0-3 yr were stratified for age and randomized to receive either continuous morphine (CM, 10 microg x kg(-1) x h(-1)) with three-hourly placebo boluses or intermittent morphine (IM, 30 microg x kg(-1) every 3 h) with a placebo infusion for postoperative analgesia. Plasma concentrations of epinephrine, norepinephrine, insulin, glucose and lactate were measured before and at the end of surgery and 6, 12 and 24 h after surgery. Pain was assessed with validated pain scales [the COMFORT scale and a visual analogue scale (VAS)] with the availability of additional morphine doses. Minor differences occurred between the randomized treatment groups, the oldest IM group (aged 1-3 yr) having a higher blood glucose concentration (P=0.003), mean arterial pressure (P=0.02) and COMFORT score (P=0.02) than the CM group. In the neonates, preoperative plasma concentrations of norepinephrine (P=0.01) and lactate (P<0.001) were significantly higher, while the postoperative plasma concentrations of epinephrine were significantly lower (P<0.001) and plasma concentrations of insulin significantly higher (P<0.005) than in the older age groups. Postoperative pain scores (P<0.003) and morphine consumption (P<0.001) were significantly lower in the neonates than in the older age groups. Our results show that continuous infusion of morphine does not provide any major advantages over intermittent morphine boluses for postoperative analgesia in neonates and infants.

Age Distribution↗

PubMed2001

Efficacy, safety and tolerability of 3 day azithromycin versus 10 day co-amoxiclav in the treatment of children with acute lower respiratory tract infections.

To compare the efficacy, safety and tolerability of a 3 day course of azithromycin with a 10 day course of co-amoxiclav in the treatment of children with acute lower respiratory tract infection (LRTI), 118 patients with community-acquired LRTI were included in a multicentre randomized double-blind, double-dummy study. The diagnosis of LRTI was based on the presence of respiratory signs and symptoms in combination with consolidation on a chest radiograph or clinical evidence of LRTI. Patients received oral azithromycin suspension (10 mg/kg/24 h) or placebo in one dose for 3 days and co-amoxiclav (45/11.25 mg/kg/24 h) or placebo in three doses for 10 days. Of 110 eligible patients, 56 and 54 patients, respectively, were treated with azithromycin or co-amoxiclav. The percentage of patients cured or clinically improved at days 10-13 (primary endpoint) was 91% for azithromycin and 87% for co-amoxiclav. This difference of 4% (90% confidence interval: -6%, +14%) was not statistically significant (P= 0.55). Significantly (P = 0.01) more related adverse events were found in the co-amoxiclav group. This was largely due to a higher percentage (43% versus 19%) of gastrointestinal complaints. A 3 day course of azithromycin (three doses) is as effective in the treatment of LRTI in children as a 10 day course of co-amoxiclav (30 doses). The azithromycin group had fewer adverse events. We conclude that azithromycin is an effective, safe and well-tolerated drug in the treatment of children with LRTI. An additional advantage is the easy administration and short duration of therapy.

Amoxicillin-Potassium Clavulanate Combination↗

PubMed2001

Use of saliva in therapeutic drug monitoring of caffeine in preterm infants.

Caffeine is frequently used to treat apnea of prematurity in preterm infants. Because caffeine has a narrow therapeutic window, plasma concentrations are generally monitored weekly. It would be advantageous to monitor this therapy without blood sampling; saliva might offer this possibility. Paired plasma-saliva and saliva-saliva observations were made in preterm infants (n = 140, gestational ages between 24 and 34 weeks) who received caffeine for the treatment of apnea of prematurity. Three methods were used to collect saliva: no stimulation, dilute citric acid on collection gauze, and dilute citric acid in the cheek pouch before collection. Plasma and saliva caffeine concentrations were determined using high-performance liquid chromatography (HPLC). For all collection methods, the plots of the plasma/saliva outcomes showed linear relationships. The correlation between caffeine concentration in plasma and saliva and the reproducibility of saliva sampling was better with stimulation of saliva production using citric acid in the cheek pouch (r = 0.89) than with no stimulation (r = 0.68) or with stimulation using citric acid on the collection swab (r = 0.79). Monitoring of caffeine therapy in saliva can be applied reliably for routine use in clinical practice, but its reliability and reproducibility depend on the saliva sampling method used; saliva stimulation with citric acid in the cheek pouch is the best method studied.

Blood Proteins↗

PubMed2001

No beneficial effects of transdermal nicotine in patients with primary sclerosing cholangitis: results of a randomized double-blind placebo-controlled cross-over study.

BACKGROUND/AIMS: Smoking is associated with a decreased risk of primary sclerosing cholangitis. We aimed to explore the therapeutic efficacy of and tolerance for transdermal nicotine treatment in this disease. METHODS: Twelve patients (11 males; 37 +/- 6 years; six with ulcerative colitis) who did not achieve complete biochemical remission on ursodeoxycholic acid (14 mg/ kg/day) were treated in a randomized cross-over trial with transdermal nicotine (15 mg/day) or a placebo, each for 8 weeks (4-week washout period between treatments). RESULTS: One patient developed de novo ulcerative colitis and two did not complete the entire protocol because of intercurrent bacterial cholangitis. Baseline values [mean (range)] were: bilirubin, 1.3 (0.5-2.6); alkaline phosphatase (APh), 2.5 (1.4-4.7); gamma-glutamyl transpeptidase (gammaGT), 7.7 (0.7-38); aspartate aminotransferase (AST), 1.9 (0.5-3.2); alanine aminotransferase (ALT), 2.4 (0.4-7.3); and bile salts, 10.9 (2.1 -39) times the upper limit of normal. No significant effect on pruritus or fatigue was noted during either period, but a small increase in bodyweight was observed during placebo treatment. No significant differences were observed between the two treatment modalities after 8 weeks in bilirubin (nicotine versus placebo, +13% versus -6% change from baseline), APh (-3% versus -17%), gammaGT (-11% versus -13%), AST (+2% versus -10%), ALT (-1% versus -11%) or bile salts (+36% versus -3%). CONCLUSION: Transdermal nicotine does not seem to have a clear short-term beneficial effect in primary sclerosing cholangitis treated with ursodeoxycholic acid.

Administration, Cutaneous↗

PubMed2001

Glycyrrhizin-induced reduction of ALT in European patients with chronic hepatitis C.

OBJECTIVE: In Japan, ALT normalization induced by long-term i.v. glycyrrhizin treatment reportedly reduces the progression of liver disease to hepatocellular carcinoma in chronic hepatitis C patients. The aim of this study was to evaluate the short-term (4-wk) feasibility and efficacy on serum ALT of three or six times per week i.v. glycyrrhizin therapy in European patients. METHODS: Patients with chronic hepatitis C, nonresponders, or unlikely to respond (genotype 1/cirrhosis) to interferon therapy were included in this study. Medication was administered i.v. three or six times per week for 4 wk; follow-up also lasted 4 wk. RESULTS: Sixty-nine out of 72 treatment courses were completed according to protocol. There were no significant changes in ALT levels within the placebo group (n = 13). The mean percentage ALT decrease from baseline at the end of treatment was 26% and 47% for the three times per week and six times per week treatment group, respectively (both p < 0.001 vs placebo). At the end of active treatment, 10% (four of 41) and 20% (three of 15) of the patients reached normal ALT levels for the three times per week and six times per week treatment group, respectively. The ALT lowering effect disappeared after cessation of treatment. No major side effects were observed. CONCLUSION: It appeared feasible to treat European outpatients with chronic hepatitis C three or six times per week with i.v. glycyrrhizin. Glycyrrhizin treatment induces a significant ALT decrease in patients with chronic hepatitis C. Six times per week treatment appears more effective than three times per week.

Adult↗

PubMed2001

Jaundice in non-cirrhotic primary biliary cirrhosis: the premature ductopenic variant.

The clinical and pathological findings of four females with primary biliary cirrhosis (PBC) with an unusual and hitherto not well recognised course are reported. Patients suffered severe pruritus and weight loss with progressive icteric cholestasis which did not respond to such treatments as ursodeoxycholic acid and immunosuppressives. In all cases liver histology revealed marked bile duct loss without however significant fibrosis or cirrhosis. Further diagnostic studies and repeat biopsies confirmed the absence of liver cirrhosis as well as other potential causes of hyperbilirubinaemia. Comparison of the fibrosis-ductopenia relationship for our cases with that for a group of 101 non-cirrhotic PBC patients indicated that in the former the severity of bile duct loss relative to the amount of fibrosis was significantly higher. The proportion of portal triads containing an interlobular bile duct was 3%, 4%, 6%, and 10% compared with 45% (median; range 8.3--100%) for controls (p<0.001). Three patients received a liver transplant 6--7 years after the first manifestation of PBC because of progressive cholestasis, refractory pruritus, and weight loss, while the fourth patient is considering this option. In one case cirrhosis had developed at the time of transplantation while the others still had non-cirrhotic disease. These cases suggest that cholestatic jaundice in non-cirrhotic PBC may be secondary to extensive "premature" or accelerated intrahepatic bile duct loss. Although the extent of fibrosis may be limited initially, progression to cirrhosis appears to be inevitable in the long run. Despite intact protein synthesis and absence of cirrhotic complications, liver transplantation in the pre-cirrhotic stage for preventing malnutrition and to improve quality of life should be considered for these patients.

Adult↗

PubMed2001

Controlled low flow off line sampling of exhaled nitric oxide in children.

BACKGROUND: The aim of this study was to validate exhaled nitric oxide (eNO) values obtained with an alternative off line, single breath, low flow balloon sampling method against on line sampling according to ERS and ATS guidelines in children who could perform both methods. METHODS: One hundred and twenty seven white children of median age 14.1 years, all pupils of a secondary school, participated in the study. They performed the two different sampling techniques at three different flows of 50, 100, 150 ml/s. Additional measurements were done in random subgroups to determine the influence of the dead space air on eNO values obtained off line by excluding the first 220 ml of exhaled air. All children completed a questionnaire on respiratory and allergic disorders and underwent spirometric tests. RESULTS: The off line eNO values were significantly higher than the on line values at all flows. At 50 ml/s the geometric mean (SE) off line eNO was 18.7 (1.1) ppb and the on line eNO was 15.1 (1.1) ppb (p<0.0001). However, when dead space air was discarded, off line and on line values were similar: at 50 ml/s off line eNO was 17.7 (1.0) ppb and on line eNO 16.0 (1.2) ppb. There was a good agreement between off line eNO values without dead space air and on line eNO: for 50 ml/s the mean on/off line ratio was 0.95 (95% agreement limits 0.63 to 1.27). The off line eNO level at 50 ml/s in 80 children with negative questionnaires for asthma, rhinitis, and eczema was 13.6 (1.0) ppb compared with 33.3 (1.1) ppb in the remaining children with positive questionnaires on asthma and allergy and/or recent symptoms of cold (p<0.0001). CONCLUSIONS: In children, off line assessment of eNO using constant low flow sampling and excluding dead space air is feasible and produces similar results as on line assessment with the same exhalation flow rate. Both sampling methods are sufficiently sensitive to differentiate between groups of otherwise healthy school children with and without self-reported asthma, allergy, and/or colds. We propose that, for off line sampling, similar low flow rates should be used as are recommended for on line measurements.

Adolescent↗

PubMed2001

Interrupter resistance in preschool children: measurement characteristics and reference values.

There is a need for quick, reliable, and noninvasive lung function tests to assess airway obstruction in preschool children both for pediatric pulmonary care as well as for research purposes. We studied feasibility, reproducibility, and validity of measurements of the respiratory system using the interrupter technique (interrupter resistance [Rint]) and obtained reference values in children from a general population, 2 to 7 yr of age. Accuracy was studied by comparisons of Rint with plethysmographic airway resistance (Raw) in 20 patients (7 to 14 yr) with mild to severe chronic airways obstruction and was satisfactory in patients with FEV(1) > 60% predicted. The technique proved sensitive enough to detect changes in airway caliber within a small group of 12 children who developed mild respiratory tract infections. Among children from a general population, subgroups with mild respiratory symptoms or mild respiratory disease had higher mean Rint values. Airway obstruction was better detected using expiratory rather than inspiratory interruptions, both programmed at peak tidal ventilatory flow. Reproducibility within subjects was satisfactory (intraclass correlation 0.82 and 0.79). The same applied to interobserver agreement (intraclass correlation 0.98). The interrupter technique proves to be a reliable and practical test of airway function, suitable for clinical and epidemiologic studies in preschool children.

Age Factors↗

PubMed2001

Off-line sampling of exhaled air for nitric oxide measurement in children: methodological aspects.

Measurement of nitric oxide in exhaled air is a noninvasive method to assess airway inflammation in asthma. This study was undertaken to establish the reference range of exhaled NO in healthy school-aged children and to determine the influence of ambient NO, noseclip and breath-holding on exhaled NO, using an off-line balloon sampling method. All children attending a primary school (age range 8-13 yrs) underwent NO measurements on two occasions with high and low ambient NO. Each time, the children performed four expiratory manoeuvres into NO-impermeable balloons, with and without 10 s of breath-holding and with and without wearing a noseclip. Exhalation flow and pressure were not controlled. NO was measured within 4 h after collection, by means of chemiluminescence. All children completed a questionnaire on respiratory and allergic disorders, and performed flow/volume spirometry. With low ambient NO, the mean exhaled NO value of 72 healthy children with negative questionnaires and normal lung function was 5.1 +/- 0.2 parts per billion (ppb) versus a mean of 6.8 +/- 0.3 ppb in the remaining 49 children with positive questionnaires for asthma and allergy, and/or recent symptoms of cold (p=0.001). Exhaled and ambient NO were significantly related, especially with ambient NO > 10 ppb (r = 0.86, p=0.0001 versus r=0.34, p=0.004 for ambient values <10 ppb). The use of a noseclip, with low ambient NO and without breath-holding, caused a small decrease in exhaled NO values (p=0.001). The effect of breath-holding on exhaled NO depended on ambient NO. With ambient NO > 10 ppb, exhaled NO decreased, whereas with ambient NO < 10 ppb, exhaled NO increased after 10 s breath-hold. It is concluded that off-line sampling in balloons is a simple and, hence, attractive method for exhaled nitric oxide measurements in children which differentiates between groups with and without self-reported asthma, allergy and colds, when ambient nitric oxide is < 10 parts per billion. Wearing a noseclip and breath-holding affected measured values and should, therefore be standardized or, preferably, avoided.

Adolescent↗