Chronic upper airway resistive loading induces growth retardation via the GH/IGF-I axis in prepubescent rats

The effect of upper airway loading on longitudinal bone growth and various components of the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis has not been fully elucidated. In the present study, the effect of chronic resistive airway loading (CAL) in a prepubescent rat model on linear bone growth and weight gain was investigated. We hypothesize that CAL induced in prepubescent rats will lead to impaired longitudinal growth due to impairment in circulating and liver GH/IGF-I parameters. The tracheae of 22-day-old rats were obstructed by tracheal banding to increase inspiratory esophageal pressure. The GH/IGF-I markers were analyzed using ELISA, RT-PCR, and Western immunoblot analysis 14 days after surgery. Animals exhibited impaired longitudinal growth as demonstrated by reduction of tibia and tail length gains by 40% ( P < 0.0001) and body weight gain by 24% ( P < 0.0001). No differences were seen in total body energy balance, i.e., oxygen consumption, daily food intake, or arterial blood gases. Circulating GH, IGF-I, and IGF binding protein-3 (IGFBP-3) levels were reduced by 40% ( P = 0.037), 30% ( P < 0.006), and 27% ( P = 0.02), respectively, in the CAL group. Liver IGF-I mRNA level decreased by 20% ( P < 0.0002), whereas GH receptor mRNA and protein expression were unchanged. We conclude that impaired longitudinal growth in prepubescent CAL rats is related to a decrease in GH, IGF-I, and IGFBP-3 levels.

Detection of K-complexes in sleep EEG using CD-HMM

In the current paper a new approach for K-complex detection using a continuous density hidden Markov model (CD-HMM) is presented. The system performance was evaluated in two manners. First using three seconds long segments of K-complexes and of background EEG (classification problem). Second using a whole night record and detecting the K complexes (detection problem). The fist test achieved an equal error rate of 7%. In the second test the system performance was compared to four trained scores that scored the signal independently. The performance of the algorithm was within the variance of the human scorers.

Elevated morbidity and health care use in children with obstructive sleep apnea syndrome

RATIONALE

Health care use, a reliable measure of morbidity, is noticeably higher 1 yr before obstructive sleep apnea syndrome (OSAS) diagnosis in preschool children. It is not clear at what age OSAS-related morbidity becomes expressed.

OBJECTIVE

To explore morbidity and health care use among children with OSAS starting from first year of life.

METHODS

Case-control study, starting from the first year of life to date of OSAS diagnosis, among 156 patients (age range, 3-5 yr) and their pair-matched healthy control subjects, by age, sex, primary care physician, and geographic location.

MEASUREMENTS

Patients with OSAS underwent nocturnal polysomnography studies. Medical records during hospital visits were reviewed for diagnosis. Variables of health care use were obtained from computerized databases of Clalit Health Care Services, the largest health maintenance organization in Israel.

MAIN RESULTS

From the first year of life to date of OSAS diagnosis, children with OSAS had 40% more (p = 0.048) hospital visits, 20% more repeated (two or more) visits (p < 0.0001), and higher consumption of antiinfective and respiratory system drugs (p < 0.0001). Referrals of children with OSAS to otolaryngology surgeons and pediatric pulmonologists were higher from Year 1 (p < 0.0001) to date of OSAS diagnosis, especially in Year 4 (odds ratio, 9.4; 95% confidence interval, 4.2-21.1). The 215% elevation (p < 0.0001) in health care use of the OSAS group was due mainly to higher occurrence of respiratory tract morbidity (p < 0.0001).

CONCLUSIONS

Practitioners should be aware that starting in Year 1 until date of diagnosis, children with OSAS have higher health care use, mostly related to respiratory diseases.

The effect of adenotonsillectomy on children suffering from obstructive sleep apnea syndrome (OSAS): the Negev perspective

OBJECTIVE

To present the Negev perspective in recent decades as to the effect of adenotonsillectomy regarding clinical and polysomnographic features, cardiopulmonary morbidity, growth, neurocognitive function, health care services utilization, and enuresis by reviewing current related literature.

METHODS

All relevant published data by the Soroka University Medical Center and related community medical services were reviewed and compared to MEDLINE linked literature regarding aspects of childhood obstructive sleep apnea published through November 2005.

RESULTS

Published data support a significant effect of adenotonsillectomy on the associated co morbidities: adenotonsillectomy resulted in the reduction of pulmonary hypertension, improved growth as a result of an increase in growth hormone secretion, improvement of neurocognitive function to the normal range, reduction in nocturnal enuresis, as well as reducing general morbidities, as reflected by the reduction in health care utilization. However, there are still uncertainties relating to major aspects. There is no specific definition for OSAS grading, or for generating a guideline for surgical treatment and refinement of the indications of T&A.

CONCLUSIONS

Adenotonsillectomy has a beneficial effect on children with OSAS, however, further research is required before recommendations for the treatment of OSAS in children can be formulated.

Low Socioeconomic Status Is a Risk Factor for Cardiovascular Disease Among Adult Obstructive Sleep Apnea Syndrome Patients Requiring Treatment

STUDY OBJECTIVE

To evaluate the possible role of low socioeconomic status (SES) as a risk factor for cardiovascular disease (CVD) among obstructive sleep apnea syndrome (OSAS) patients requiring treatment.

DESIGN

Polysomnographic and demographic characteristics and associated morbidity were measured in 686 prospectively recruited adult OSAS patients from two regions in Israel.

SETTING

Two university-affiliated sleep laboratories.

MEASUREMENTS AND RESULTS

The multiple logistic regression (after adjusting for gender, body mass index [BMI], and smoking) revealed that the following are independent determinants for CVD in OSAS patients requiring treatment: each decrease in income level category (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.1 to 1.7), age > or = 1 year (OR, 1.07; 95% CI, 1.04 to 1.1), hypertension (OR, 2.0; 95% CI, 1.3 to 3.1), and hyperlipidemia (OR, 3.7; 95% CI, 2.4 to 5.8); area under the receiver operating characteristic (ROC) = 81.9%. The multivariate determinants describing the low-SES OSAS patients included: minorities and immigrants combined (OR, 6.0; 95% CI, 2.9 to 12), female gender (OR, 2.4; 95% CI, 1.6 to 3.9), increased BMI (OR, 1.9; 95% CI, 1.3 to 2.9), unmarried status (OR, 1.9; 95% CI, 1.2 to 3.1), and years of education (> or = 1 year) [OR, 0.8; 95% CI, 0.7 to 0.8]; area under the ROC = 78.1%.

CONCLUSION

In addition to the already known traditional risk factors, low SES was found to be a novel independent risk factor for CVD among adult OSAS patients requiring treatment.

Adenotonsilectomy improves enuresis in children with obstructive sleep apnea syndrome

OBJECTIVES

To evaluate the prevalence of nocturnal enuresis (NE) in children diagnosed with obstructive sleep apnea syndrome (OSAS) and the effect of tonsillectomy and adenoidectomy on enuresis.

DESIGN, SETTING, AND PARTICIPANTS

All children 4-18 years of age who underwent polysomnography (PSG) between January 2003 and May 2004 were included (n=161). The evaluation was based on a retrospective review of a standard sleep questionnaire and a full overnight PSG, followed by an additional structured telephone questionnaire performed 9 months after adenotonsillectomy (T&A) (range 5-14).

RESULTS

We identified 144 (89%) children with an apnea hypopnea index >1. Of these 144 children, 42 [29.2% (95% CI, 21.8-36.6)] were reported to have enuresis, 27 of these 42 underwent T&A. Among the 27 enuretic children who had undergone adenotonsillectomy, 74.1% had 3 or more wet nights per week before the procedure compared to 37%, 1 month after [n=27 (chi2=3.308, McNemar pv<0.0001)]. Of the 27 children who underwent adenotonsillectomy, any decrease in enuresis severity was reported by 70.4% (95% CI 53.2-87.62), while in 56% of these 27 (95% CI 41.96-70.06) it occurred 1 month postoperatively. In 11/27 children (41%), enuresis totally disappeared within 1 month, while in 3/27 (11%) enuresis disappeared throughout the remaining time of follow-up.

CONCLUSIONS

Obstructive sleep apnea in children is frequently associated with nocturnal enuresis. Adenotonsillectomy has a favorable therapeutic effect on enuresis in children with obstructive sleep apnea presenting this symptom.

Determinants Affecting Health-Care Utilization in Obstructive Sleep Apnea Syndrome Patients

STUDY OBJECTIVE

To investigate determinants of health-care utilization in patients with obstructive sleep apnea syndrome (OSAS).

DESIGN

Case-control prospective study with OSAS patients and a control group. We compared 218 patients with OSAS to those of age-, gender-, geographically-, and family physician-matched control subjects from the general population, matched 1:1 (chi2 = 0.999).

PARTICIPANTS

All participants were members of Clalit Health Care Services, a health maintenance organization in the southern region of Israel. All OSAS patients underwent nocturnal polysomnography studies. Indexes of health-care utilization 2 years prior to the polysomnography were analyzed.

MEASUREMENTS AND RESULTS

Health-care utilization was 1.7-fold higher (p < 0.001) in the OSAS patients due to more hospitalization days (p < 0.001), consultations (p < 0.001), and cost for drugs (p < 0.05), particularly those for the cardiovascular system. In comparison to men, women consumed significantly more health-care resources (p < 0.001). OSAS patients < or = 65 of age years consumed 2.2-fold more health-care resources than control subjects (p < 0.001). Polysomnography findings and OSAS severity and body mass index (BMI) did not predict health-care utilization, using multivariate logistic regression analysis. Age > 65 (odds ratio [OR], 2.2; p < 0.04) and female gender (OR, 2.0; p < 0.05) were the leading elements predicting the most costly OSAS patients. Arbitrarily dividing the OSAS group by cost of health-care utilization, the upper 25% (n = 55) of patients who were the "most costly" consumed sevenfold more health-care resources than the lower 75% of the patients. This was due to higher comorbidity, ie, 10 to 30% more hypertension, ischemic heart disease, diabetes mellitus, and pulmonary disease.

CONCLUSIONS

OSAS patients are heavy users of health-care resources. Age > 65 years and female gender were the leading elements predicting the most costly OSAS patients, and not necessarily patients with a high BMI and classic OSAS severity indexes.

Chronic resistive airway loading reduces weight due to low serum IGF-1 in rats

One of the consequences of chronic resistive airway loading in rats is malfunction in body weight gain post-surgery. The lower body weight of the obstructed animals was not related to lower caloric intake or to the oxygen consumption/food intake ratio. In the current study, we determined whether the retardation in body weight gain was related to impairment of serum insulin-like growth factor-1 (IGF-1) level or due to activation of inflammatory factors 21 weeks post-surgery. During the observation period, the airway-loaded animals (n=8) gained 44% less body weight (P<0.001) compared with controls (n=8) with no apparent effect on skeletal growth, i.e., body, tail and tibia length. Chronic airway-loaded animals had 32.5% lower serum IGF-1 levels (P<0.001) compared to the controls. Interleukin-6 and tumor necrosis factor-alpha levels were below 30 pg/ml in both groups. These data suggest that the weight loss in the chronic airway-loading rats is associated with a decreased IGF-1 level and not to activation of the inflammatory response.

Determinants affecting initiation of continuous positive airway pressure treatment

BACKGROUND

Continuous positive airway pressure is the treatment of choice for patients with obstructive sleep apnea syndrome.

OBJECTIVE

To determine the factors influencing treatment initiation with a CPAP device in a healthcare system in which co-payment is required.

METHODS

A total of 400 adult patients with OSAS who required CPAP therapy completed questionnaires at three different stages of the diagnostic and therapeutic process: CPAP titration study (stage 1), patient adaptation trial (stage 2), and purchase of a CPAP device (stage 3). Logistic regression was used to analyze the variables influencing CPAP use at the different stages of the diagnostic and therapeutic processes.

RESULTS

Only 32% of the patients who underwent CPAP titration study purchased a CPAP device. The number of subjects who purchased a CPAP device increased gradually as monthly income increased, 28% vs 62% in the "very low" and "very high" income levels respectively. Reporting for the titration increased in patients with excessive daytime sleepiness and an Epworth Sleepiness Scale score above 9 (odds ratio = 1.9, P = 0.015). Higher socioeconomic status increased reporting to stage 2 (OR = 1.23, P = 0.03) and CPAP purchase (stage 3, OR = 1.35, P = 0.002). Excessive daytime sleepiness increased reporting to stage 2 (OR = 2.28, P = 0.006). Respiratory disturbance index above 35 increased CPAP purchasing (OR = 2.01, P = 0.022). Support from the bed partner, referring physician and sleep laboratory team increased CPAP purchasing.

CONCLUSIONS

A supportive environment for a patient with OSAS requiring CPAP is crucial to increase initiation of CPAP treatment. Minimizing cost sharing for the CPAP device will reduce inequality and may increase CPAP treatment initiation.

Awareness Level of Obstructive Sleep Apnea Syndrome During Routine Unstructured Interviews of a Standardized Patient by Primary Care Physicians

OBJECTIVE

To assess the awareness level of primary care physicians of obstructive sleep apnea syndrome during patient-physician encounters.

DESIGN

A prospective study using a standardized patient approach, conducted between December 2001 and March 2002. Ten sleep experts reviewed and approved the checklist questionnaire.

SETTING

Primary care clinics of Clalit Health Care Services, in the central region of Israel.

PARTICIPANTS

Thirty physicians (100% compliance) randomly selected (matched by age, sex, board certification) from the 261 primary care givers in the region.

INTERVENTION

A standardized patient incorporated into the physicians' daily practices.

RESULTS

From the original checklist questionnaire, we identified 2 related question areas that at least 90% of sleep experts would pursue in light of the presenting scenario, "Do the patients snore, choke, or stop breathing in sleep?" and "Does the patient have sleepiness, unrefreshed sleep/fall asleep at undesirable times?" During the unstructured interview, only 10% of the physicians asked 3 or more questions. More than 85% of primary care physicians identified the need for polysomnography evaluation (27 physicians) or continuous positive airway pressure (26 physicians) treatment for obstructive sleep apnea syndrome. However, only 16% and 50% discussed possible complications of obstructive sleep apnea syndrome such as motor vehicle and work accidents and cardiovascular events, respectively.

CONCLUSIONS

Primary care physicians cannot identify a common disorder associated with cardiovascular and neurobehavioral disease and could not identify the sleepiness as a source of dangerous driving. While understanding the algorithms for the diagnosis of sleep apnea, physicians cannot identify the patients for whom the diagnostics are needed. Education programs need to be developed to increase the level of suspicion of obstructive sleep apnea syndrome among practicing primary care physicians. Activities can be monitored and evaluated over time in the daily practice by standardized patients.

EDUCATIONAL OBJECTIVE

Increased awareness level of obstructive sleep apnea syndrome among primary care physicians, through publications and educational programs, monitored by standardized patients.

Obstructive sleep apnea syndrome: the diagnostic strategy dilemma

Obstructive sleep apnea syndrome is a major public health hazard affecting 2-4% of the adult population; only 10% of these patients are recognized by healthcare providers. In the last decade the number of referrals for polysomnography increased threefold in Israel, compared to 12-fold worldwide, and is expected to increase even more in the coming years. This constant demand for PSG studies is beyond the current capacity of sleep laboratories, thus preventing diagnosis for most patients with suspected OSAS. In the current review, we examine problems facing decision-makers on how to treat the increasing flood of patients presenting with symptoms suggestive of sleep-disordered breathing. We evaluate the cost-effectiveness of current technologies for OSA diagnosis, i.e., laboratory versus at-home technologies. We conclude that no current alternative exists to the use of PSG for OSA diagnosis. When at-home technologies are suggested for OSAS diagnosis, data should be provided on factors influencing its cost-effectiveness, e.g., accuracy rates of diagnosis, relative cost of human resources, and case-mix of patients tested. Since PSG remains the gold standard for diagnosis of OSAS, in Israel resources should be allocated to increasing the volume of beds for PSG studies in order to increase access to diagnosis and treatment, which in turn provides better quality of life, saves scarce resources of the healthcare system, prevents unnecessary accidents and increases workers' productivity.

Willingness to pay for polysomnography in children with obstructive sleep apnea syndrome: a cost-benefit analysis

OBJECTIVES

To analyze willingness to pay (WTP) for polysomnography (PSG) among parents of children with obstructive sleep apnea syndrome (OSAS). To analyze the cost-benefit of PSG in a collectively funded healthcare system.

SETTING

University-affiliated sleep laboratory.

SUBJECTS

Parents of 158 boys and 94 girls, who had a mean age of 6.0 +/- 3.9 years. The telephone survey, using a contingent valuation approach, was conducted with 3 groups of parents: those whose children were scheduled for PSG (n = 83), whose children were had had PSG within the previous 6 months (n = 77), and whose children had had PSG and adenotonsillectomy in the previous 6 months (n = 92).

RESULTS

Two hundred and fifty-two parents (92% compliance rate), 75% of whom were mothers, responded to the WTP interview. Multivariate analysis revealed that the independent variables influencing WTP were bid (OR = 0.745, P < .001), age times bid (OR = 0.835, P < .05), and affected health status (OR = 3.5, P < .001). The median WTP value for PSG studies of children with OSAS following adenotonsillectomy was dollars 762 plus the savings of dollars 60 to the health care system-subtracting the cost of the dollars 250 PSG study resulted in a monetary benefit of dollars 572 per diagnosis.

CONCLUSIONS

We conclude that PSG diagnosis for children with OSAS is beneficial. Decision makers and sleep specialists can use WTP to prioritize allocation of resources to increase the availability of PSG studies for children.

Adenotonsillectomy improves neurocognitive function in children with obstructive sleep apnea syndrome

OBJECTIVE

To evaluate neurocognitive functions of children with obstructive sleep apnea syndrome (OSAS), before and after adenotonsillectomy, compared with healthy controls.

DESIGN

Prospective study.

PATIENTS AND METHODS

Thirty-nine children with OSAS aged 5 to 9 years (mean age, 6.8 +/- 0.2 years) and 20 healthy children (mean age, 7.4 +/- 1.4 years) who served as controls, underwent a battery of neurocognitive tests containing process-oriented intelligence scales. Twenty-seven children in the OSAS group underwent follow-up neurocognitive testing 6 to 10 months after adenotonsillectomy. Fourteen children in the control group were also reevaluated 6 to 10 months after the first evaluation.

RESULTS

Children with OSAS had lower scores compared with healthy children in some Kaufman Assessment Battery for Children (K-ABC) subtests and in the general scale Mental Processing Composite, indicating impaired neurocognitive function. No correlation was found between neurocognitive performance and OSAS severity. Six to 10 months after adenotonsillectomy, the children with OSAS demonstrated significant improvement in sleep characteristics, as well as in daytime behavior. Their neurocognitive performance improved considerably, reaching the level of the control group in the subtests Gestalt Closure, Triangles, Word Order, and the Matrix analogies, as well as in the K-ABC general scales, Sequential and Simultaneous Processing scales, and the Mental Processing Composite scale. The magnitude of the change expressed as effect sizes showed medium and large improvements in all 3 general scales of the K-ABC tests.

CONCLUSIONS

Neurocognitive function is impaired in otherwise healthy children with OSAS. Most functions improve to the level of the control group, indicating that the impaired neurocognitive functions are mostly reversible, at least 3 to 10 months following adenotonsillectomy.

Polysomnographic and actigraphic evidence of sleep fragmentation in patients with irritable bowel syndrome

STUDY OBJECTIVE

To characterize the function and quality of sleep in patients with irritable bowel syndrome (IBS).

DESIGN

A prospective study with a historic comparison group.

SETTING

A regional hospital that also serves as a tertiary referral center.

PATIENTS

Eighteen patients with IBS and a comparison group of 20 matched adults with mild benign snoring.

INTERVENTIONS

A polysomnography study and a wrist actigraphy study.

MEASUREMENTS

All subjects underwent sleep studies and completed self-report questionnaires (IBS severity, psychosocial variables, sleep function, and Epworth Sleepiness Scale). Fourteen IBS and 11 comparison patients underwent actigraphy.

RESULTS

The IBS patients had more than 70% less slow-wave stage sleep (4.5 +/- 7.3% vs 19.3 +/- 12.9%; P = 0.006), compensated by increased stage 2 sleep (72.2 +/- 6.6% vs 60.1 +/- 16.8%; P = 0.01). The IBS group had significant sleep fragmentation with a significantly higher arousal and awakening index (P < 0.001), a longer wake period after sleep onset (P = 0.02), and more downward shifts to lighter sleep stages (P = 0.01). The 4-night actigraphy study supported the polysomnography findings. The sleep fragmentation index was significantly higher (P = 0.008) in the IBS group. The IBS patients reported greater daytime sleepiness (9.0 +/- 4.8 vs 6.4 +/- 4.8, Epworth Sleepiness Scale score, P < 0.01) and greater impairment in quality of life, which correlated significantly with the sleep fragmentation indexes. The difference between the groups was not due to differences in baseline anxiety/depression levels.

CONCLUSIONS

Patients with IBS have impaired sleep quality, reduced slow-wave sleep activity, and significant sleep fragmentation. The cause-and-effect relationship of these findings with patients' daytime symptoms should be studied further.

Adenotonsillectomy in children with obstructive sleep apnea syndrome reduces health care utilization

OBJECTIVE

To investigate health care utilization of children with obstructive sleep apnea syndrome (OSAS) 1 year after adenotonsillectomy (T&A).

METHODS

A longitudinal, case-controlled, prospective study was conducted at Clalit Health Care Services (CHS), a health maintenance organization in the southern region of Israel. We defined 3 groups of children: 1) children who had OSAS and were treated with T&A (n = 130); 2) children who had OSAS and did not undergo surgery (n = 90); and 3) control subjects who were matched by age, sex, and area of residency (n = 520) and randomly selected from the CHS database. OSAS was verified with polysomnography studies in all patients. Indices of health care utilization were analyzed 1 year before and 1 year after T&A. Medical records in the emergency department and during hospitalization were reviewed for diagnosis before the polysomnography diagnosis.

RESULTS

Mean age of all children with OSAS was 5.6 +/- 3.6 years. Total annual health care costs were reduced by one third in children who underwent T&A, whereas there was no change in the control and untreated OSAS groups. T&A was associated with a 60% reduction in the number of new admissions, 39% reduction in emergency department visits, 47% reduction in the number of consultations, and 22% reduction in costs for prescribed drugs. In group 2, the total costs were similar in years 1 and 2.

CONCLUSIONS

T&A significantly reduces health care utilization in children with OSAS. Untreated children with moderate and severe OSAS will continue to consume high levels of health care resources. Increased morbidity among children with OSAS is mainly related to upper respiratory tract infections.

Sleep characteristics following adenotonsillectomy in children with obstructive sleep apnea syndrome

OBJECTIVE

To compare the effect of adenotonsillectomy on rapid eye movement (REM)- and non-REM-related respiratory and sleep architecture characteristics in children with obstructive sleep apnea syndrome (OSAS).

STUDY DESIGN

This prospective study evaluated 36 children (median age, 6.9 years; range, 1.8 to 12.6 years) with OSAS using polysomnography before and a few months after adenotonsillectomy. Primary outcomes included the number of obstructive apnea and hypopnea and arousals per hour of sleep.

RESULTS

At 4.6 months (range, 1 to 16 months) after adenotonsillectomy, there was a significant improvement of all respiratory parameters. The median respiratory disturbance index (RDI) decreased from 4.1/h (range, 0 to 85/h) to 0.9/h (range, 0 to 13/h) after adenotonsillectomy (p < 0.0001). The median non-REM RDI decreased from 3.0/h (range, 0 to 89/h) to 0.4/h (range, 0 to 13/h) [p < 0.001] as compared with REM RDI, which decreased from 7.8/h (range, 0 to 69/h) to 2.3/h (range, 0 to 54/h) after adenotonsillectomy (p < 0.01). Median arousal index decreased following adenotonsillectomy from 17.5/h (range, 7 to 57/h) to 14.0/h (range, 6 to 47/h) [p < 0.03].

CONCLUSIONS

Adenotonsillectomy resulted in a greater improvement in non-REM RDI as compared with REM-RDI, and a decrease in the number of arousals.

Complications of adenotonsillectomy in children with OSAS younger than 2 years of age

The most common sleep disorder in children is obstructive sleep apnea syndrome (OSAS). The majority of children with OSAS improve following tonsillectomy and adenoidectomy (T&A). T&A as an outpatient procedure in children is very common. Young age in considered risk factors for postoperative respiratory complications. The purpose of this study is to analyze our experience with postoperative T&A complications in patients younger than 2 years of age. A total of 39 T&A were performed in children younger than 2 years of age. OSAS diagnosis was confirmed by overnight polysomnography (PSG). All the patients were hospitalized and monitored by overnight pulse oximetry monitoring. Post-operatively there was marked improvement in respiratory function in all the patients comparing pre- and post-operative nadir oxygen saturation (P<0.05). Complications were documented in seven patients (20%). Five of the complications occurred in children older than 1 year of age. Bleeding occurred in two patients (5.7%). Three patients (8.6%) had dehydration, one patient (2.9%) had hypercarbia and one patient had laryngospasm. In this study there was a low incidence of peri- and post- operative respiratory complications in children younger than 2 years of age who undergo T&A for OSAS. Identification of OSAS severity may be an important factor in determining the risk of T&A in a young child.

Antivenom serotherapy and volume resuscitation partially improve peripheral organ ischemia in dogs injected with scorpion venom

We tested the hypothesis that fluid resuscitation combined with antivenom serotherapy given after injection of scorpion venom may increase cardiac output (CO) and blood pressure (BP) and prevent the decline in bicarbonate, pH and gastric perfusion. Seventeen anesthetized, mechanically ventilated dogs were given 0.1 mg/kg i.v. venom of the scorpion Leiurus quinquestriatus. The dogs were randomized into three groups: six dogs were given venom alone; three dogs were given 6 ml of antivenom 1 minute before venom injection; eight dogs were given 6 ml of antivenom and 20 ml/kg of synthetic colloid solution, 20 min after venom injection. Parameters reflecting respiratory and circulatory functions were determined at baseline and 120 min after venom injection. Scorpion venom caused a decrease in CO, BP, pH and HCO3-. Gastric mucosal perfusion was severely affected as assessed by mucosal pH (pHi) and the gradient between mucosal and arterial pCO2 (delta pCO2). Antivenom given before venom injection prevented all the effects induced by the venom. Antivenom and fluid given 20 min after venom injection caused a marked increase in CO and BP, but had no effect on pH and HCO3- decline (compared with venom alone). Gastric perfusion slightly improved as the increase in delta pCO2 was attenuated. The combination therapy of antivenom and fluid in this dog model is superior to the therapy of each of them alone. The marked and long-standing improvement of CO is promising and may suggest improvement in HCO3- and pH with time.

Sleep disruption and objective sleepiness in children with beta-thalassemia and congenital dyserythropoietic anemia

BACKGROUND

Sleep fragmentation and periodic leg movement syndrome (PLMS) have been reported in adults with iron deficiency anemia. Little is known about sleep function and daytime sleepiness in children with chronic anemia such as beta-thalassemia or congenital dyserythropoietic anemia type 1 (CDA-1).

OBJECTIVES

To investigate if children and adolescents who have beta-thalassemia (major or intermedia) or CDA-1 experience sleep fragmentation and objective daytime sleepiness and also to investigate if children and adolescents with beta-thalassemia have obstructive sleep apnea.

METHODS

Ten patients (7 males and 3 females) with beta-thalassemia (mean [SD] age, 10.4 [7.3] years), 10 patients (7 males and 3 females) with CDA-1 (mean [SD] age, 13.5 [5.1] years), and 13 healthy volunteer control children(7 males and 6 females) (mean [SD] age, 10 [4] years) underwent nocturnal polysomnographic studies. A multiple sleep latency test was performed for 6 patients who had beta-thalassemia and 8 patients who had CDA-1.

RESULTS

Both patient groups, that is, those who had beta-thalassemia and those who had CDA-1, had multiple arousals during sleep (mean [SD], 27.8 [11.4] events per hour and 23.8 [11.8] events per hour, respectively) compared with the control subjects (12.1 [6.6] events per hour) (P<.002). Thirty-eight percent (10.6 events per hour) of the arousals in patients with beta-thalassemia and 25% (6.0 events per hour) of the arousals in patients with CDA-1 were induced by periodic limb movements during sleep. In the control group, most (98%) arousals were spontaneous and unrelated to any definable event. The multiple sleep latency test average was 7.8 minutes for patients with beta-thalassemia (n = 6) and 10.7 minutes for patients with CDA-1 (n = 8). Five patients with beta-thalassemia and 4 patients with CDA-1 underwent a second polysomnographic study on the next night to confirm reproducibility. There was no significant change in the total number or index of arousals and no difference in the severity of the periodic limb movements during sleep compared with the results of the first polysomnographic study.

CONCLUSION

Children and adolescents with beta-thalassemia or CDA-1 have evidence of impaired sleep function that is partially due to periodic limb movements during sleep and arousals that result in objective diurnal sleepiness.

Effect of Venom from the Scorpion Leiurus Quinquestriatus on Rat Vascular Aortic Rings

The present study was designed to examine the effects of venom from the scorpion Leiurus quinquestriatus hebraeus (Lqh) on the contractility of rat aortic rings. We first examined the effect of Lqh venom on the contractile tension of isolated rat vascular aortic rings and then whether long-term exposure to the venom reduces the contractility of vascular smooth muscle by increasing the production of nitric oxide. Following the administration of 33 microg/mL of crude Lqh venom, contractile tension increased by 18.9 +/- 11.4 percent. The administration of 2.4 x 10(-7) M noradrenaline (NA) led to a 31.6 +/- 8.2 percent increase in tension (p < 0.01). The effects induced by NA and Lqh venom were similar and additive (p < 0.01). Pretreatment with the alpha-adrenergic blocker phenoxybenzamine (0.2 microM) eliminated the effect of the venom, whereas the calcium-channel blocker verapil (8.3 microM) merely attenuated the effect. Incubation of the rings with Lqh venom for 16 to 18 h, followed by NA stimulation, led to a 15 to 20 percent decrease in tension (p < 0.001). Treatment with N-omega-nitro-L-arginine methyl ester (110 microM), a constitutional nitric oxide inhibitor, restored the tension to control values. Treatment with S-methyl-isothiourea (0.1 microM), an inducible nitric oxide synthesis inhibitor, had no effect on contractile tension. The results of the present study suggest that the effect of Lqh venom on isolated aortic rings is induced via sympathetic nerve terminals. Calcium had little effect on the smooth muscle contractility of aortic rings incubated with the venom. No evidence was found to support nitric oxide synthesis after the long-term exposure of the rings to Lqh venom.

Health care services utilization in children with obstructive sleep apnea syndrome

OBJECTIVE

Little is known about the effects of obstructive sleep apnea syndrome (OSAS) on utilization of health care services in children. The present study compares medical service utilization by children with OSAS with that of healthy children.

METHODS

A cross-sectional study of 287 consecutively recruited children (1-18 years) with OSAS and no concomitant diseases and a control group matched by age, gender, and geographic location was conducted at the Clalit Health Care Services clinic in the southern region of Israel. Children in the study group underwent nocturnal polysomnography (PSG) studies. The control group (N = 1149) was randomly selected from the Clalit Health Care Services database. PSG was performed for the OSAS patients. Indices of health care utilization 1 year before the PSG study were analyzed.

RESULTS

A 226% increase in health care utilization was noted among children with OSAS. Children up to 5 years of age consumed more health care resources than children over 5 years. Children with OSAS consumed more health care services than the control group at all ages. The leading components of this high cost are utilization of more hospital days, drugs, and visits to the emergency department. The severity of the OSAS correlates directly to total annual costs and independently to age (beta = 0.19).

CONCLUSIONS

Children with OSAS are heavy consumers of health care services 1 year before any specific evaluation and treatment for apnea. Early diagnosis and intervention may be cost-effective.

Volume resuscitation does not alleviate peripheral organ ischemia in dogs injected with scorpion venom

OBJECTIVES

To examine the effect of fluid resuscitation on the hemodynamic changes in dogs injected with scorpion venom and to explore the effects of the venom on the determinants of venous return (i.e., circulatory compliance, time constant, and resistance to venous return).

DESIGN

A prospective, controlled animal study.

SETTING

University animal research laboratory.

SUBJECTS

Mixed-breed dogs.

INTERVENTIONS

The effect of volume resuscitation (20 mL/kg of the synthetic colloid polygeline) 1 hr after venom injection (a time previously found to be related to severe decrease in cardiac output) was tested in two series of experiments. In the first series, 12 dogs were given venom and fluid, eight dogs were given venom alone, and four dogs served as the time-controlled group. In the second series, eight dogs were given venom and ten dogs served as controls. Scorpion venom (Leiurus quinquestriatus) at 0.1 mg/kg in the first series and 0.05 mg/kg in the second series was given intravenously.

MEASUREMENTS AND MAIN RESULTS

In the first series of experiments, the venom decreased cardiac output from 5.0 +/- 1.1 to 2.9 +/- 0.7 L/min at 60 mins (p <.001). Arterial pH decreased from 7.39 +/- 0.05 to 7.16 +/- 0.1 (p <.001). Blood lactate increased from 0.9 +/- 0.8 to 3.2 +/- 1.9 mM (p <.05). Gastric pH decreased from 7.28 +/- 0.2 to 6.7 +/- 0.18 (p <.001). Arterial acidosis was secondary to gastrointestinal ischemia because the gradient between mucosal and arterial Pco2 increased from 17.5 +/- 7.7 to 98.6 +/- 75 (p <.01) 60 mins after venom injection. In the second series of experiments, circulatory compliance and time constant increased by 150% and 128%, respectively (p <.05), in dogs injected with venom compared with control dogs. Resistance to venous return increased after venom injection but did not change after fluid infusion. In both series of experiments, volume administration improved cardiac output but had no effect on oxygen delivery, arterial pH, HCO3-, lactate, and gastric mucosal pH.

CONCLUSIONS

Metabolic acidosis and cardiovascular abnormalities seen after scorpion venom injection in dogs are closely related to gastrointestinal hypoperfusion. Fluid resuscitation increased cardiac output but had no effect on gastrointestinal perfusion and acidosis induced by the venom.

[Impaired daytime functions in children with sleep disorders]

Sleep in adequate amount and quality is essential for normal child development. Sleep disorders may affect the childs daytime functions resulting in behavioral problems such as attention deficit, aggressiveness and hyperactivity. Recent reports have suggested that chronic sleep disturbance can cause neurocognitive deficits and impaired learning abilities. Obstructive sleep apnea syndrome, asthma, atopic dermatitis and juvenile rheumatoid arthritis--are common childhood diseases that can impair normal sleep. This article reviews the sleep characteristics in these diseases and the relation between sleep quality and the social and intellectual performance of the child during the day.

A cost-effectiveness analysis of alternative at-home or in-laboratory technologies for the diagnosis of obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a common disorder that affects 2% to 9% of the population. Health care policy makers have noted increased referrals for sleep studies.

OBJECTIVE

In this article, the authors conduct a cost-effectiveness analysis to determine the optimal technology for the diagnosis of OSAS using polysomnography (PSG) or partial sleep monitoring (PSM).

DESIGN

The target population was a hypothetical cohort of patients suspected of having OSAS. A 2-level decision tree wasformulated that reflects all possible steps of OSAS diagnosis and therapy. The method represents a comprehensive strategy to determine which of the 2 systems-PSG or PSM-has cost advantages. The financial and operational aspects of OSAS diagnosis and therapy were analyzed. A sensitivity analysis was performed over all uncertain parameters (i.e., diagnostic agreement, data loss, and referral to therapy).

RESULTS

Unattended at-home sleep monitoring was the most expensive method. The combination of 1:2 PSG and attended PSM strategy was the optimal strategy with respect tofinancing and operations. Compared to the PSG-only strategy, this combination may lead to a 10% reduction of the annual expenditure.

CONCLUSION

This study provides proof of concept (under a wide range of sensitivity assumptions) that the cost of sleep study techniques can be modeled. It rejects the assumption that athome portable sleep monitoring is cost advantageous. The combination of PSG and attended PSM OSAS is the most cost-effective approach to sleep evaluation.