["Somatic symptom disorders" in adolescence. A systematic review of the recent literature]. / « Troubles à symptomatologie somatique ¼ chez les adolescents. Une revue systématique.

OBJECTIVES: Body expression of mental disorders is common in adolescence. Only two literature reviews over the last five years have been identified about somatoform disorders in children., The present article provides a systematic review of articles in English, which concern "Somatic Symptom and Related Disorders" according to the DSM-5 (Diagnostic and Statistical Manual - 5th Edition) among adolescents. METHODS: The article search was made on Medline, Psychinfo, Google Scholar, BiomedCentral, Central and tripdatabase (for grey literature) according to PRISMA criteria and with the items "somatoform disorders" or "somatic symptom disorders". An age filter was applied for "adolescents", and a selection was done from the last five years. All articles concerning adolescents (often associated with children) were initially included, except for articles concerning eating disorders, dysmorphic disorders or adult population. Comments, editorials, opinion or descriptive articles were also excluded. The authors then carried out an analysis of the main topics, themes and questions covered in the selected publications and presented a descriptive synthesis. RESULTS: A total of seventy-seven publications were included in the analysis, from three hundred and seventy-two publications. First, the terms used to refer to these "somatic symptom disorders" were varied, such as "somatization", "somatic complaints/symptoms", "functional disorder", "unexplained symptoms" and "somatoform disorders". Then, studies related just to adolescents were limited: most of studies included children and adolescents in their methodologies; and some of them questioned somatic symptoms from a developmental perspective. Case reports were the most represented articles among all medical specialties, with clinical descriptions about "functional neurological symptom disorder", "factitious disorder" and "somatic symptom disorder" with a medical disease, among children and adolescents. We sometimes observed a controversial borderline between psychological and somatic disorders. Various explanatory models appeared, especially the trauma path; familial and social environment was also pointed out, with a possible peer group effect; neurocognitive theories were finally described. The literature highlights the effectiveness of psychosocial therapies (especially the cognitive-behavioral therapy) and the importance of multidisciplinary management. Finally, a few studies with a qualitative methodology are represented. CONCLUSIONS: Only nine articles included "somatic symptom disorder" in their titles, despite a terminology valued by many authors (compared to "somatoform disorders" from the DSM-IV). The heterogeneity of terminologies, case reports and explanatory models witness a lack of connexions between medical specialties. This could explain in part the wandering of adolescents and their families in the health care system. It could also contribute to the delay before diagnosis, especially when neurological symptoms exist, and a late referral for psychiatric consultation. Further studies are needed to understand difficulties to use a clinical pathway among medical specialties, when the benefit of amultidisciplinary approach seems to be unanimous.

[Externalizing behaviour problems of internationally adopted adolescents: a review]. / Troubles du comportement externalisés à l'adolescence et adoptions internationales: revue de la littérature.

INTRODUCTION: International adoption involves more than 40 000 children a year. The objective of this review is to estimate the effects of international adoption on externalizing behaviour problems during adolescence. In this paper we examine the prevalence of externalizing problem behaviours in samples of adolescents who were adopted from a foreign country as infants or young children, compare to non-adopted adolescents. SETTING: We searched Medline, Inist and psycInfo from 1960 to 2005 using the terms adopt* combined with behaviour problem, behaviour disorder, maladjustment or mental health. METHODS: The search was limited to English and French-language publications. Studies that were selected involved adoptees in the general population and compared international adoptees with non-adopted controls. Adoptees from 12 to 22 years old were included. We included studies using the Child Behaviour Check List or related measures to measure externalizing problem behaviour. We reviewed 10 studies from 1990 to 2002 and 2 meta-analyses (2003, 2005). RESULTS: Results indicate that 6 studies conclude that internationally adopted adolescents exhibit more externalizing behaviour problems than do non-adopted adolescents, and 4 studies conclude that there is no difference between the two groups. The two meta-analyses concluded that the prevalence of externalizing behaviour problems is increased. The difference, however, is small. International adoptees with preadoption adversity showed more externalizing problems than international adoptees whithout evidence of extreme deprivation. CONCLUSION: Finally, it should be stressed that adoption itself is not a risk factor in the adjustment of adolescents. Differences between groups of adopted and non-adopted adolescents may reflect the presence of a small number of severely disturbed adolescents, possibly with extremely adverse pre-placement histories.

Computation of ventilation-perfusion ratio with Kr-81m in pulmonary embolism.

Diagnostic difficulties occur in pulmonary embolism (PE) during visual analysis of ventilation-perfusion images in matched defects or in chronic obstructive lung disease (COPD). In 44 patients with angiographically confirmed PE and in 40 patients with COPD, the regional ventilation-perfusion ratios (V/Q) were therefore computed using krypton-81m for each perfusion defect, and were displayed in a functional image. In patients with PE and mismatched defects, a high V/Q (1.96) was observed. A V/Q greater than 1.25 was also found in nine of 11 patients having PE and indeterminate studies (studies with perfusion abnormalities matched by radiographic abnormalities). COPD was characterized by matched defects and low V/Q. The percentage of patients correctly classified as having PE or COPD increased from 56% when considering the match or mismatched character to 88% when based on a V/Q of 1.25 in the region of the perfusion defect. This quantitative analysis, therefore, seems useful in classifying patients with scintigraphic suspicion of PE.

Effects of rilmenidine on bronchomotor responses in the guinea pig.

This study compares the effects of 2 alpha 2-adrenergic agonists, rilmenidine (S 3341) and clonidine, on histamine-induced bronchoconstriction (HIB) in guinea pigs. Clonidine has previously been shown to potentiate HIB in guinea pigs. The study was conducted in anesthetized, paralyzed and ventilated guinea pigs. Six groups of at least 6 guinea pigs were pretreated with saline, rilmenidine (0.1, 0.3 and 1 mg/kg intravenously) or clonidine (0.01 and 0.03 mg/kg intravenously), respectively. Conductance, dynamic compliance and static compliance of the respiratory system were measured before and during histamine infusion (80 ng/kg/s) and expressed as percent variation. Clonidine potentiated HIB as previously reported. In contrast, rilmenidine potentiated HIB only at the dose of 1 mg/kg. As it is well known that HIB is influenced by adrenergic outflow, these results suggest that rilmenidine has less inhibitory effect than clonidine on adrenal secretion.

Failure of enhancement by labetalol of bronchopulmonary effects of histamine in guinea-pigs: independence of alpha-adrenoceptor antagonism.

The effect of labetalol on histamine-induced bronchoconstriction was studied in anaesthetized guinea-pigs. Unlike propranolol (1 mg kg-1), the same dose of labetalol did not enhance histamine-induced bronchoconstriction. To determine whether the absence of enhancement of the respiratory effects of histamine by labetalol was due to its alpha 1-blocking properties or to its partial agonist activity at beta 2-adrenoceptors, the effects of propranolol plus prazosin and of propranolol plus labetalol on histamine-induced bronchoconstriction were examined. In both cases, the bronchoconstrictor effects of histamine were enhanced to the same extent as with propranolol alone. These data support the hypothesis that the non impairment of respiratory mechanics by labetalol is not due to antagonism at alpha-adrenoceptors and may be mediated by its partial agonist activity at beta 2-adrenoceptors.

5-Hydroxytryptamine-induced bronchoconstriction in the guinea-pig: effect of 5-HT2 receptor activation on acetylcholine release.

1. The bronchoconstrictor responses to 5-hydroxytryptamine (5-HT) were studied in the guinea-pig to establish whether they are partly attributable to parasympathetic activation within the airways. 5-HT dose-response curves were constructed in anaesthetized and ventilated guinea-pigs pretreated with saline, or by bilateral cervical vagotomy or vagotomy plus atropine 3 mg kg-1, i.v. Vagotomy had no effect on 5-HT-induced bronchoconstriction but vagotomy plus atropine significantly reduced it. 2. To determine whether parasympathetic activation within the airways resulted from pre- or postganglionic stimulation, 5-HT dose-response curves were constructed for two groups of vagotomized guinea-pigs treated with hexamethonium 2 mg kg-1, or hexamethonium 2 mg kg-1, plus atropine 3 mg kg-1. Guinea-pigs treated with hexamethonium plus atropine experienced significantly less 5-HT-induced bronchoconstriction than those treated with hexamethonium alone. 3. To characterize the subtype of 5-HT receptors involved in the activation of the parasympathetic system by 5-HT, dose-response curves to 5-HT were constructed for four groups of vagotomized guinea-pigs treated with saline, 1 mg kg-1 of the 5-HT3 antagonist ICS 205-930, or either 0.01 or 0.1 mg kg-1 of the 5-HT2 antagonist ketanserin. ICS 205-930 enhanced 5-HT-induced bronchoconstriction but 0.01 mg kg-1 ketanserin inhibited it significantly and 0.1 mg kg-1 ketanserin abolished it. To confirm the involvement of 5-HT2 receptors in these responses, we studied the effects in vagotomized guinea-pigs of atropine on the bronchoconstriction induced by the 5-HT2 agonist,x alpha-methyl-5-HT, infused at rates of 40 and 80ngkg-1s-'. At both rates, atropine significantly reduced the bronchoconstrictor responses to alpha-methyl-5-HT. 4. The above results indicate that 5-HT-induced bronchoconstriction is indeed partly mediated by parasympathetic activation within the airways. This activation is mediated by stimulation of 5-HT2 receptors which are probably located on the postganglionic parasympathetic nerve endings.

Prevalence of sleep-disordered breathing in patients on a heart transplant waiting list.

We investigated the prevalence of sleep-disordered breathing in 20 outpatients on a heart transplant waiting list. All were younger than 60 years and had severe stable cardiac failure with a cardiac index below 2.5 L/min/m2 and a left ventricular ejection fraction below 25%. Nine patients (45%) exhibited ten or more apneas and hypopneas per hour of sleep (apneic group). In all patients but one, apneas and hypopneas were predominantly of the central type and occurred during Cheyne-Stokes respiration. There were no statistically significant differences between the apneic and nonapneic groups of patients in terms of age (51 +/- 5 years vs 49 +/- 11), body mass index (24 +/- 4 kg/m2 vs 22 +/- 3), cardiac index (1.87 +/- 0.35 L/min/m2 vs 1.84 +/- 0.40), isotopic left ventricular ejection fraction (13 +/- 5 vs 12 +/- 3%), arterial blood gas, or pulmonary function tests. Hypnogram characteristics showed poorer sleep quality in the apneic group than in the nonapneic group, with a larger number of arousals; this difference was found both for arousals lasting more than 30 s (8 +/- 5/h vs 4 +/- 2) and for arousals lasting less than 30 s (18 +/- 16/h vs 5 +/- 6) and was associated with increased wakefulness after sleep onset in the apneic group (138 +/- 82 min vs 84 +/- 45). Arousals were strongly associated with hyperpneic phases of Cheyne-Stokes respiration. We conclude that sleep-disordered breathing is common in patients with end-stage heart disease and adversely affects the quality of sleep.

Effects of obesity on respiratory resistance.

To assess the effects of obesity on pulmonary function, 46 healthy subjects exhibiting various degrees of obesity underwent lung function tests. Subjects were divided into three groups according to body mass index (BMI): 13 had minimal obesity (BMI, 25 to 29 kg/m2, group 1); 24 had a BMI in the 30 to 40 range (group 2); and 9 displayed to morbid obesity (BMI > 40, group 3). Respiratory resistance was estimated by the forced random noise oscillation technique and airway resistance was determined by body plethysmography. Lung volumes and expiratory flows were also determined and significant negative correlations with BMI were found. Expiratory flows diminished in proportion to lung volumes, and the ratio of forced expiratory volume in 1 s to forced vital capacity was within normal limits. Although expiratory flows did not suggest bronchial obstruction, both respiratory resistance and airway resistance rose significantly with the level of obesity (p < 0.005 and p < 0.025, respectively), from 3.2 (+/- 0.02) and 3.2 (+/- 0.02) cm H2O.s.L-1, respectively, in group 1, to 5.5 (+/- 0.06) and 5.0 (+/- 0.05), respectively, in group 3. Evaluation of the factors responsible for this increased resistance disclosed a significant linear correlation between airway conductance and functional residual capacity (r = 0.70, p < 10(-4)), but specific airway conductance was found to be independent of the degree of obesity. The difference between respiratory resistance and airway resistance did not widen significantly according to the level of obesity, suggesting that chest wall resistance was not a factor enhancing these resistances. Taken together, these findings suggest that in addition to the elastic load, obese subjects have to overcome increased respiratory resistance resulting from the reduction in lung volumes related to being overweight.

Cardiopulmonary effects of a single oral dose of almitrine at rest and on exercise in patients with hypoxic chronic airflow obstruction.

Almitrine, a new triazine derivative, was studied in a double-blind, randomized, parallel study in 16 patients with hypoxic chronic airflow obstruction (eight almitrine and eight placebo). At rest, compared to placebo, a 3 mg/kg single dose of almitrine given orally significantly increased the partial pressure of oxygen (mean increase: +12.0 +/- SEM 2.1 mm Hg, p less than 0.001) and decreased the partial pressure of carbon dioxide (mean decrease: -6.0 +/- 0.7 mm Hg, p less than 0.001); this improvement in arterial blood gases persisted on exercise. The lack of significant change in ventilation and the decrease in the alveolar-arterial oxygen gradient (mean decrease -10.0 +/- 1.9 mm Hg; p less than 0.001) at rest suggests a change in the distribution of the ventilation-perfusion ratio in the lung; such a change was confirmed by a krypton 81m isotopic study. Pulmonary hemodynamic responses were studied at rest and on exercise; a significant but slight increase in mean pulmonary artery pressure at rest (+4.0 +/- 1.5 mm Hg, p less than 0.05) was found.

Mechanisms of impaired arterial oxygenation in patients with liver cirrhosis and severe respiratory insufficiency. Effects of indomethacin.

The mechanisms of impaired arterial oxygenation that occur in certain patients with chronic liver cirrhosis are still debated. In the present study, we investigated nine cirrhotic patients with severe respiratory disability (mean PaO2, 64 +/- 5 mm Hg), using the inert gas elimination technique to assess the distribution of ventilation-perfusion (VA/Q) ratios. We also determined shunt fraction during pure oxygen breathing, both in supine and sitting positions. To test the hypothesis that vasodilating prostaglandins could contribute to alter gas exchange in such patients with cirrhosis, we examined the hemodynamic and gasometric responses to indomethacin, 50 mg IV, in six of them. During baseline conditions, patients had high cardiac index (CI, 4.9 +/- 0.2 L/min/m2), and low pulmonary (PVR, 1.78 +/- 0.37 mm Hg/L/min/m2) or systemic (SVR, 17.7 +/- 1.15 mm Hg/L/min/m2) vascular resistances. Large intrapulmonary shunt fraction was documented in each patient with a mean value of 19.6 +/- 2.7 percent. Small perfusion in low VA/Q areas was associated with shunt in only three patients (2.5 to 5.3 percent of blood flow). Arterial PO2 was negatively related to shunt (p < 0.01) and to the dispersion of blood flow distribution (p < 0.02). There was no difference between measured and predicted PaO2. Shunt estimates from the inert gas and the 100 percent O2 breathing techniques were, respectively, 19.6 +/- 2.7 percent and 21.7 +/- 3.0 percent. During 100 percent oxygen breathing, changing from supine to sitting position decreased PaO2 from 401 +/- 50 to 333 +/- 64 mm Hg (p < 0.02), while O2 shunt remained unchanged, arteriovenous difference widened, and mixed venous PO2 decreased, from 61 +/- 3 to 47 +/- 4 mm Hg (p < 0.001). Indomethacin did not improve gas exchange or VA/Q distribution and did not affect systemic or pulmonary hemodynamics. The results show that in cirrhotic patients with severe respiratory disability, intrapulmonary shunting is the main determinant of impaired gas exchange, with no evidence of a defect in oxygen diffusion or an extrapulmonary shunt. Vasodilating prostaglandins do not appear to contribute to these alterations.

Forced oscillation technique vs spirometry to assess bronchodilatation in patients with asthma and COPD.

The forced oscillation technique (FOT) is a noninvasive test used to characterize the mechanical impedance of the respiratory system. The aim of the study was to compare the changes in respiratory conductance (Grs) measured with FOT to those in FEV1 in 22 patients with asthma and 20 patients with chronic obstructive pulmonary diseases (COPD) after salbutamol inhalation. FEV1 and Grs indexes, computed as the ratio of the difference between postbronchodilator and prebronchodilator values over the predicted value, were used to express reversibility of airway obstruction. After inhalation of salbutamol in cumulative doses up to 1,200 micrograms in ten patients of each group, FEV1 and Grs indexes showed parallel changes, and most of the increase was observed after the first dose of 200 micrograms of salbutamol for the two indexes. In all the 42 patients, we found a linear relationship between the two indexes after inhalation of 200 micrograms of salbutamol (r = 0.7, p < 0.0001). We evaluated FEV1 and Grs indexes in terms of sensitivity and specificity for identifying asthmatics among patients with COPD: using a 10% change as the cut-off value, these indexes proved of similar value (sensitivity, 0.91 and 0.95; specificity, 0.95 and 0.85, respectively). We conclude that the use of FOT can be considered as an alternative to forced expiration for detecting bronchodilatation in asthmatics and patients with COPD.

Evaluation of carbon dioxide rebreathing during pressure support ventilation with airway management system (BiPAP) devices.

The purpose of this study was to evaluate whether carbon dioxide (CO2) rebreathing occurs in acute respiratory failure patients ventilated using the standard airway management system (BiPAP pressure support ventilator; Respironics; Murrysville, Pa) with positive inspiratory airway pressure and a minimal level of positive end-expiratory pressure (PEEP) and whether any CO2 rebreathing may be efficiently prevented by the addition of a nonrebreathing valve to the BiPAP system circuit. In the first part of the study, the standard device was tested on a lung model with a nonrebreathing valve (BiPAP-NRV) and with the usual Whisper Swivel connector (BiPAP-uc). With the BiPAP-uc device, the resident volume of expired air in the inspiratory circuit at the end of expiration (RVEA) was 55% of the tidal volume (VT) when the inspiratory pressure was 10 cm H2O and the frequency was at 15 cycles per minute. The BiPAP-NRV device efficiently prevented CO2 rebreathing but resulted in a slight decrease in VT, which was due to a significant increase in external PEEP (2.4 vs 1.3 cm H2O) caused by the additional expiratory valve resistance. For similar reasons, both the pressure swing necessary to trigger pressure support and the imposed expiratory work were increased in the lung model when the nonrebreathing valve was used. In the second part of the study, seven patients weaned from mechanical ventilation were investigated using a randomized crossover design to compare three situations: pressure support ventilation with a conventional intensive care ventilator (CIPS), BiPAP system use, and BiPAP-NRV. When we compared the BiPAP system use with the other two systems, we observed no significant effect on blood gases but found significant increases in VT, minute ventilation, and work of breathing. These findings are experimental and are clinical evidence that significant CO2 rebreathing occurs with the standard BiPAP system. This drawback can be overcome by using a non-rebreathing valve, but only at the expense of greater expiratory resistance.

PEEP-induced airspace overdistension complicating paraquat lung.

This report describes a case of paraquat poisoning, treated with continuous positive airway pressure. After an initial phase of acute respiratory failure with diffuse pulmonary edema, we observed radiologically a complete clearing of both lungs, associated with an aspect of overdistension. Surprisingly, FRC was above normal, as was total quasi static compliance. The patient died on the 15th day, with intractable hypoxemia. Pathologic analysis revealed large zones of parenchyma with overdistended airspaces, explaining the emphysematous-like aspect of the lungs. We propose that the attempts to increase lung volume with CPAP, at an early phase of diffuse epithelial disorganization, may have, partially at least, dilated the remaining distal airspaces.

Combined effects of a mechanical nasal dilator and a topical decongestant on nasal airflow resistance.

The goal of this study was to compare the isolated and combined effects of two treatments being used to reduce nasal airflow resistance (NR): an internal nasal mechanical dilator (Nozovent; Prevancure; Sté Pouret, Paris, France) and a topical decongestant, fenoxazoline hydrochloride (Aturgyl; Synthelabo; Le Plessis-Robinson, France). The study was performed in 17 healthy subjects. NR was estimated by active posterior rhinometry at a 0.5 L/s flow under four conditions: in the basal state, with the internal nasal mechanical dilator, after treatment with fenoxazoline hydrochloride, and with both fenoxazoline hydrochloride and the mechanical dilator. The mean NR (+/- SD) decreased from 1.65+/-0.54 cm H2O/L/s in the basal state to 1.02+/-0.27 cm H2O/L/s with the mechanical dilator (p < 0.001), 1.03+/-0.47 cm H2O/L/s with fenoxazoline hydrochloride (p < 0.001), and 0.48+/-0.15 cm H2O/L/s with both the mechanical dilator and fenoxazoline hydrochloride (p < 0.001). The decreases in NR observed after using either the mechanical dilator (deltaNR(N)) or fenoxazoline hydrochloride (deltaNR(A)) were not significantly different. The decrease in NR observed with both (deltaNR(N + A)) was not significantly different from the sum deltaNR(N) + deltaNR(A): 1.16+/-0.53 cm H2O/L/s vs 1.25+/-0.63 cm H2O/L/s, respectively (p > 0.05). deltaNR(N + A) strongly correlated with deltaNR(N) + deltaNR(A): deltaNR(N + A) = 0.80 (deltaNR(N) + deltaNR(A)) + 0.15 (r = 0.96; p < 0.0001). However, the slope of the regression line of deltaNR(N + A) vs deltaNR(N) + deltaNR(A) was significantly lower than unity (p < 0.003). These results demonstrate that, although not totally additive, the effects of using the mechanical dilator and fenoxazoline hydrochloride are cumulative. Further studies that include patients with nasal obstruction would allow us to better evaluate the benefit of a therapy combining both treatments.

Arterial blood pressure response to transient arousals from NREM sleep in nonapneic snorers with sleep fragmentation.

STUDY OBJECTIVES: To assess the hemodynamic effects of graded arousals during nonrapid eye movement (NREM) sleep in patients with partial upper airway obstruction during sleep without obstructive sleep apnea/hypopnea, overnight beat-to-beat BP was recorded in six patients. SETTING: At the end of each nonapneic obstructive event, EEG responses were graded as follows: grade 2, grade 1, and grade 0 were defined as increased high-frequency EEG lasting >15 s, 3 to 15 s, and no EEG arousals according to the American Sleep Disorders Association, respectively. MEASUREMENTS AND RESULTS: The following were observed during grade 0, 1, and 2 EEG patterns (mean+/-SD): systolic pressure increased by 7.1+/-1.5, 11.7+/-1.9, and 14.2+/-3.4 (p<0.005), respectively; diastolic pressure increased by 4.6+/-0.6, 6.7+/-1.7, and 9.4+/-3.0 (p<0.005), respectively; heart rate increased by 2.9+/-0.4, 3.9+/-2.2, and 8.6+/-4.6 (p<0.005), respectively. CONCLUSIONS: We conclude that nonapneic-nonhypopneic obstructive events are followed by arterial systemic pressure increases whose magnitude varies with the grade of the arousal.

Sleep fragmentation as a risk factor for hypertension in middle-aged nonapneic snorers.

Although a high prevalence of hypertension has been observed in snorers, whether there is a direct link between hypertension and snoring remains controversial. It has recently been demonstrated that an abnormal amount of breathing effort during snoring is responsible for sleep fragmentation even in the absence of sleep apnea syndrome criteria. We hypothesized that sleep fragmentation during snoring may be a direct risk factor for the development of hypertension. On the basis of polysomnographic data, 105 nonapneic patients between 40 and 65 years of age referred for snoring with social impairment were selected and categorized as snorers with (n=55) or without sleep fragmentation (n=50) based on whether the arousals index was 10 or greater or less than 10/h of sleep, respectively. Sleep distribution did not differ between the two groups, except for a longer duration of wake after sleep onset (58 +/- 43 min vs 42 +/- 38 min) and a shorter duration of slow-wave sleep in the group with sleep fragmentation (72 +/- 34 min vs 97 +/- 34 min). Although there were no statistically significant differences between the snorers with and without sleep disruption in terms of age (51.3 +/- 7.7 vs 48.6 +/- 6.0 years), body mass index (26.9 +/- 4.0 vs 27.2 +/- 5.5 kg/m2), sex ratio, respiratory indexes during sleep, daytime sleepiness, and daytime tiredness, prevalence of systemic hypertension was significantly higher in the sleep-fragmented group (20/55 vs 7/50). This significant difference persisted (16/51 vs 6/49) when patients using antihypertensive drugs with possible effects on the CNS were excluded. Our data suggest that sleep fragmentation is common in patients who seek medical help for snoring with social impairment and may play a role in the development of hypertension.

Abdominal muscle activity in sleep apnea during continuous positive airway pressure titration.

STUDY OBJECTIVES: The aim of this study was to investigate whether presence of expiratory abdominal muscle activity (EAMA) in obstructive sleep apnea syndrome (OSAS) patients during nasal continuous positive airway pressure (nCPAP) is due to either nCPAP overprescription or nCPAP underprescription. DESIGN: Airflow, esophageal pressure (Pes), and gastric pressure (Pga) were routinely measured during polysomnography aimed at determining the optimal nCPAP level, and the magnitude of EAMA was evaluated in relation to the nCPAP level and to the conventional indexes of upper-airway obstruction used during nCPAP titration. PATIENTS: The study was performed 12 patients with OSAS. RESULTS: Six patients displayed sustained EAMA, ie, EAMA lasting > 3 min, and characterized by a decrease in abdominal diameter and a paradoxical rise in Pga during expiration. In all six patients, EAMA decreased gradually as nCPAP neared optimal levels, and then disappeared when the optimal nCPAP level was achieved. The decrease in EAMA as nCPAP increased was associated with an increase in minute ventilation, decreases in both inspiratory and expiratory resistance, a decrease in Pes swing, and the normalization of the inspiratory flow contour. CONCLUSIONS: We conclude that the EAMA observed in some OSAS patients might be an indirect marker of upper-airway obstruction, and that the presence of EAMA during nCPAP titration might indicate a suboptimal nCPAP level rather than a deleterious effect of nCPAP.

Use of glass capillaries avoids the time changes in high blood PO(2) observed with plastic syringes.

STUDY OBJECTIVES: In adults, arterial blood samples are usually drawn using plastic syringes. In contrast to glass syringes, plastic syringes let oxygen diffuse through their wall. This results in PO(2) changes during storage, especially when PO(2) is high. An alternative to glass syringes is the Microsampler (Roche Diagnostics; Schaffhausen, Switzerland), a commercially available device consisting of a heparinized glass capillary fitted with a 26-gauge needle and used to collect arterial blood in the same way as a plastic syringe fitted with a needle. DESIGN: We evaluated the performance of the Roche Microsampler for storing arterial blood in view of PO(2) measurement, comparatively with glass and plastic syringes. Five approximate initial PO(2) levels (650, 400, 200, 130, and 80 mm Hg) and two storage temperatures (ambient temperature and 4 degrees C) were studied. SETTINGS: Bench study. RESULTS: Plastic syringes allowed reliable measurement of PO(2) values when initial PO(2) was too low to ensure complete hemoglobin oxygen saturation, but were associated with time-dependent underestimation of PO(2) at higher initial PO(2) values. No such underestimation occurred with the Roche Microsampler stored at 4 degrees C for up to 1 h for all PO(2) levels studied. CONCLUSION: The Roche Microsamplers appeared to be reliable devices in preventing oxygen diffusion.

Total respiratory pressure-volume curves in the adult respiratory distress syndrome.

To assess the value of measuring compliance in the adult respiratory distress syndrome, sequential pressure-volume curves were obtained in 19 patients with this syndrome. Analysis of the pressure-volume curves allowed separation of the patients into the following four groups: (1) group 1 (n = 6), normal compliance measured during deflation, little hysteresis, and no inflection in the ascending limb of the pressure-volume tracing; (2) group 2 (n = 8), normal compliance during deflation, increased hysteresis, and presence of an inflection; (3) group 3 (n = 10), decreased compliance during deflation, marked hysteresis, and presence of an inflection; and (4) group 4 (n = 10), reduced compliance during deflation, no increased hysteresis, and no inflection. These patterns were correlated with the stage of the adult respiratory distress syndrome and to the pattern of the chest x-ray film. Group 2 corresponds to the initial stage of the syndrome and to pure alveolar opacities on the chest x-ray film. Group 3 is seen later in the course of the syndrome and corresponds to mixed alveolar and interstitial opacities. Group 4 corresponds to patients with end-stage adult respiratory distress syndrome (two weeks) and a predominant interstitial pattern on the chest x-ray film. Group 1 corresponds to a nearly normal chest x-ray film and to recovery.

Effects of nasal prongs on nasal airflow resistance.

STUDY OBJECTIVES: The aim of this study was to investigate whether nasal prongs, which have been proposed to assess nasal flow during sleep, affect nasal airflow resistance (NR). DESIGN: NR was estimated by posterior rhinomanometry at a 0.5 L/s flow, under eight conditions: in the basal state, and with seven different nasal prongs. PARTICIPANTS: The study was performed in 17 healthy supine subjects, 8 of whom had basal NR values within the normal range (< or = 2 cm H(2)O.L(-1).s, group 1), and 9 had increased basal NR values (> 2.5 cm H(2)O.L(-1).s, group 2), because of nare narrowness and/or deviated nasal septum. MEASUREMENTS AND RESULTS: NR increased significantly while breathing with nasal prongs (p < 0.0001 in both groups). The changes in NR (DeltaNR) induced by the different nasal prongs were characterized by large intersubject and intrasubject variability, with a maximum DeltaNR of 24.2 cm H(2)O.L(-1).s. Significant differences were found between the DeltaNR induced by the different nasal prongs (p < 0.001 in group 1, and p < 0.0003 in group 2), and for six of them, DeltaNR was significantly higher in group 1 than in group 2 (p < 0.02). CONCLUSIONS: This study demonstrates that nasal prongs can markedly increase NR in subjects presenting with nare narrowness and/or deviated nasal septum. Further investigations that would include nocturnal polysomnography are still required to evaluate the possible influence of nasal prongs on the diagnosis of obstructive sleep apnea syndrome and its severity.