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Background SARS-CoV-2 virus which targets the pulmonary vasculature is supposed to induce an intrapulmonary right to left shunt with an increased pulmonary blood flow. Such vascular injury is difficult to observe because it is hidden by the concomitant lung injury. We report here what may be, to the best of our knowledge, the first case of a pure Covid-19 related Acute Vascular Distress Syndrome (AVDS). Case presentation A 43-year-old physician, tested positive for Covid-19, was addressed to the emergency unit for severe dyspnoea and dizziness. Explorations were non informative with only a doubt regarding a sub-segmental pulmonary embolism (no ground-glass lesions or consolidations related to Covid-19 disease). Dyspnoea persisted despite anticoagulation therapy and normal pulmonary function tests. Contrast-enhanced transthoracic echocardiography was performed which revealed a moderate late right-to-left shunt. Conclusions This case report highlights the crucial importance of the vascular component of the viral disease. The intrapulmonary shunt induced by Covid-19 which remains unrecognized because generally hidden by the concomitant lung injury, can persist for a long time. Contrast-enhanced transthoracic echocardiography is the most appropriate test to propose in case of persistent dyspnoea in Covid-19 patients.

Background: The impact of removing the upper airway lymphoid tissue and in particular, tonsillectomy, in adults with OSA has not been demonstrated in large populations. Aims: To compare the severity of OSA and the prevalence of cardiovascular, metabolic and respiratory co-morbidities between patients with OSA who had undergone previous tonsillectomy and those who had not. Methods: The 19,711 participants in this study came from the European sleep apnea database (ESADA) which comprises data from unselected adult patients aged 18–80 years with a history of symptoms suggestive of OSA referred to sleep centers throughout Europe. Results: There were no differences between the two groups in terms of sex ratio and age (146 patients with previous tonsillectomy vs. 19565 patients without). Patients who had undergone tonsillectomy had a lower body mass index (29.3 ± 5.2 kg/m2 vs 32.2 ± 6.6 kg/m2, p < 0.001), lower subjective sleep latency (17.1 ± 17.8 min vs 25.5 ± 30.4 min, p = 0.001), lower ODI (15.7 ± 18.3 events/hour vs 30.7 ± 26.1 events/hour, p < 0.001), and SpO2, European Respiratory Society, ERS, The ESADA network has previously received support from the European Union COST action B26 and the European Respiratory Society. We gratefully acknowledge unrestricted seeding grants from ResMed Inc and Philips Respironics Inc. for establishment of the organisation and the database. Excellent technical assistance in terms of centre monitoring and database maintenance was provided by Ann-Christin Lundquist, RN and Jeanette Norum, RN.

DEAR SIR, We read with great interest the recent letter to the Editor by Lavinia Monaco et al. [1] about the article by Jeeban P. Das et al. [2] that were both published in your European Journal of Nuclear Medicine and Molecular Imaging. In six patients with a laboratory-confirmed diagnosis of COVID-19 and a moderate or high pre-test probability of pulmonary embolism (PE), perfusion (Q)-single-photon emission computed tomography (SPECT)/CT was found positive in 4/6 of patients with bilateral and segmental PE in 3/4 of patients. [...]

Background and aim: Obstructive sleep apnea (OSA) is an independent risk factor for dyslipidemia. The current study examined the effects of positive airway pressure (PAP) treatment on lipid status in the European Sleep Apnea Database (ESADA). Methods: The prospective cohort study enrolled 1564 OSA subjects (74% male, mean age 54 ± 11y, body mass index (BMI) 32.7 ± 6.6 kg/m2 and apnea-hypopnea index (AHI) 40.3 ± 24.4 n/h) undergoing PAP therapy for at least three months (mean 377.6 ± 419.5 days). Baseline and follow-up total cholesterol (TC) from nine centers were analyzed. Repeated measures and logistic regression tests (adjusted for age, sex, weight changes, lipid lowering medication, PAP compliance, and treatment duration) were used to compare changes in TC concentration. Incident risk for a coronary heart disease event (CHD) was used to compute a Framingham CHD risk score (estimated from age, BMI, blood pressure, and TC). Results: Adjusted means of TC decreased from 194.2 mg/dl to 189.3 mg/dl during follow-up (p = 0.019). A clinically significant (10%) reduction of TC at PAP follow-up was observed in 422 patients (27%). Duration of PAP therapy was identified as independent predictor for TC reduction, which implies an approximately 10% risk reduction for incident CHD events (from 26.7% to 24.1% in men and from 11.2% to 10.1% in women, p < 0.001 respectively). Conclusion: This observational study demonstrates a reduction of TC after long-term PAP treatment. The close association between TC concentration and cardiovascular (CV) mortality suggests that identification and treatment of OSA may have a beneficial effect on overall CV risk due to this mechanism. This possibility needs to be evaluated in prospective randomized studies. © 2020 Elsevier B.V., ResMed Foundation European Respiratory Society, ERS European Respiratory Society, ERS European Respiratory Society, ERS, The ESADA network has received support from the European Union COST action B26 and the European Respiratory Society (ERS) funded Clinical Research Collaboration (CRC). Unrestricted seeding grants from the ResMed Foundation and the Philips Respironics Foundation for establishment of the database in 2007 and 2011 are gratefully acknowledged. The ESADA network has a scientific collaboration with Bayer AG., Nonfinancial support was provided by the European Sleep Research Society (ESRS) and the European Respiratory Society (ERS) in terms of logistics for communication, meetings and data presentations for the ESADA collaborators., Dr. Verbraecken reports grants and personal fees from ResMed, Bioprojet, Jazz Pharmaceutics; personal fees from Philips, Sanofi, Agfa-Gevaert, grants from AirLiquide; personal fees from Springer, Westfalen Medical, SomnoMed, Vivisol, Total Care, Medidis, Fisher & Paykel, Wave Medical, OSG, Mediq Tefa, NightBalance, Heinen & Löwenstein, AstraZen, Accuramed, Bekaert Deslee Academy and UCB Pharma, outside the submitted work. Dr. Hedner reports grants from ResMed, Philips Respironics, and the European Respiratory Society all related to maintenance of database on behalf of the ESADA group during the conduct of the study. Dr. Grote reports grants from Bayer, Resmed, Respironics/Philips, and from the European Respiratory Society during the conduct of the study; non-financial support and other from Itamar Medical, Resmed, Philips, and Astra Zeneca, outside the submitted work. In addition, Dr. Grote has a patent on sleep apnea therapy licensed. The remaining co-authors have no conflict of interest to declare.

Objective/Background: The Clinical Global Impression scale (CGI) reflects the clinician's assessment of the disease impact on patient's global functioning. We assessed predictors of CGI scale rating in patients with obstructive sleep apnea (OSA). Patients/Methods: Consecutive patients with suspected OSA (n = 7581) were identified in the European Sleep Apnea Database (ESADA). Anthropometrics, comorbidities, apnea severity obtained by polygraphy or polysomnography, and daytime sleepiness [Epworth Sleepiness Scale (ESS)] were assessed. The CGI 7-point scale was completed at the end of the diagnostic process (CGI-severity, ie, CGI-S) and, in a sub-population, at treatment follow-up (CGI-Improvement). Results: CGI-S was rated mild to moderate in 44% of patients. CGI rating at any given apnea intensity was worse in women than in men (p < 0.01). Patients undergoing polygraphy (n = 5075) were more frequently rated as severely ill compared to those studied with polysomnography (19.0% vs 13.0%, p < 0.001). In patients aged

Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent chronic respiratory disorder with prevalence among adult males of ≥10%. The most common daytime symptom associated with OSAS is excessive sleepiness, which in more severe manifestations can result in sleepiness at the wheel while driving and probably contributes to the substantial increase in accident risk among patients with OSAS. Fortunately, current evidence indicates that successful therapy of OSAS, particularly with continuous positive airway pressure, can bring the accident risk down to levels similar to an equivalent general population. The recognition of the increased driving accident risk in OSAS prompted the Transport and Mobility Directorate of the European Commission to establish a working group on this topic in 2012, which ultimately led to a revision of Annex III of the EU Driving Licence Directive, which is subject to mandatory implementation by European Union member states by December 2015. This directive specifies that patients with moderate or severe OSAS associated with significant daytime sleepiness should be prohibited from driving until effective therapy is established. These new regulations are designed to balance the legitimate objective of public safety with not penalising OSAS patients who are complying with effective therapy. Successful implementation of regulations on driving in OSAS patients must also include measures to educate relevant stakeholders including patients, medical personnel, traffic police and employers in the transport industry. The key objective is to encourage patients with possible OSAS to seek diagnosis and treatment and not to inhibit OSAS patients from coming forward.

Purpose of the study Periodic leg movements (PLMs) are found in 30% of patients suffering from OSA. Under CPAP, we observed that PLMs can increase, decrease, or remain unchanged. The predictors of these changes are not well established. Objective To determine the predictors of PLMs change under CPAP and its impact on long-term adherence. Materials and method The patients were referred to the sleep laboratory for snoring or sleepiness. A single PSG night has been performed before and after CPAP treatment. Data on medication used, comorbidities and ferritin level were collected. Results A total of 160 patients were recruited with a severe OSA. About 32.5% (52/160) patients had emerging PLM i.e. that appeared after the disappearance of respiratory events. By comparing patients with emerging-PLMs to others, we found that only the blood ferritin level was significantly different between groups. Moreover, after one-year follow-up, a significant difference in adherence and long-term compliance was observed between patients without PLM at both screening and CPAP polysomnographies or emerging PLM at the second study (56%) vs. patients with baseline PLM, whether PLM remained stable or decreased under CPAP treatment (75%) (p-value 0.028). Serum ferritin and presence of diabetes mellitus predicted the evolution of PLM observed. Patients with low ferritin levels demonstrated an increase of PLM after initiation of nasal CPAP treatment. Conclusion The emergence of PLM negatively impacts long-term adherence to nasal CPAP treatment in OSA. Blood ferritin level is a predictor of the evolution of PLM under CPAP therapy.

In Belgium, patients with moderate to severe OSA (AHI 20) who show less than 30 micro-arousals per hour slept (MAI) cannot benefit from CPAP refund by the social security (SS).To assess the influence of reimbursement on CPAP acceptance, and long-term adherence.OSA patients (AHI 20) were included regardless of MAI. All patients were offered a CPAP trial of 3-5 days for habituation. Two groups were defined and compared: «Out of pocket money» patients (OOP) with MAI 30 that were invited to purchase their device and «reimbursed group» that were offered a CPAP reimbursed by the social security.812 patients were found: 59 in the OOP group, mostly females, sleepier and using more hypnotics. Out of the reimbursed group, 183 patients were matched to the OOP patients on the grounds of age, AHI and BMI. 90% of OOP and 94% of reimbursed patients (p 0.379) accepted a CPAP trial; 74% of OOP and 90% of reimbursed patients acquired a CPAP device (p 0.005) thereafter, whereas 82% and, respectively, 84% of those (p 0.254) were still on CPAP after a mean follow-up of 711 and 604 days with a mean ± SD daily compliance of 5.3 ± 3 and 6.1 ± 2 h, respectively (p 0.159). Only fatigue scale seems to influence the purchase of CPAP by OOP patients.CPAP reimbursement influences the purchase of CPAP but once the device becomes available there is no difference with reimbursed patients in long-term adherence.

Sleepiness may account for up to 20% of crashes on monotonous roads, especially highways. Obstructive sleep apnea (OSA) is the most common medical disorder that causes excessive daytime sleepiness, increasing the risk for drowsy driving two to three times. The purpose of these guidelines is to update the 1994 American Thoracic Society Statement that described the relationships among sleepiness, sleep apnea, and driving risk.A multidisciplinary panel was convened to develop evidence-based clinical practice guidelines for the management of sleepy driving due to OSA. Pragmatic systematic reviews were performed, and the Grading of Recommendations, Assessment, Development, and Evaluation approach was used to formulate and grade the recommendations. Critical outcomes included crash-related mortality and real crashes, whereas important outcomes included near-miss crashes and driving performance.A strong recommendation was made for treatment of confirmed OSA with continuous positive airway pressure to reduce driving risk, rather than no treatment, which was supported by moderate-quality evidence. Weak recommendations were made for expeditious diagnostic evaluation and initiation of treatment and against the use of stimulant medications or empiric continuous positive airway pressure to reduce driving risk. The weak recommendations were supported by very low-quality evidence. Additional suggestions included routinely determining the driving risk, inquiring about additional causes of sleepiness, educating patients about the risks of excessive sleepiness, and encouraging clinicians to become familiar with relevant laws.The recommendations presented in this guideline are based on the current evidence, and will require an update as new evidence and/or technologies becomes available.

The physiology of sleep is not completely understood but it is widely accepted that sleep is important to the human body in the recovery of metabolic and neurological processes. This paper summarizes the effects of sleep dysfunction on different systems and considers implications in the context of rehabilitation. When sleep is experimentally completely or partially curtailed important brain functions are impacted leading to psychological and neurological disturbances. Increased cortisol levels, reduction of glucose tolerance, and increased sympathetic nervous system activity have also been identified in healthy subjects under such conditions. Several studies show that 50-80% of patients with chronic pain suffer from sleep dysfunction. It has been suggested that on the one hand pain can cause sleep dysfunction and on the other hand that sleep dysfunction can aggravate pain. The physiologic mechanism behind this interaction is not completely clear; although most authors describe the relationship between pain and sleep dysfunction as aberrant processing of tactile-cutaneous sensory inputs at the meso-encephalic level and in the trigeminal nucleus both when asleep and awake. Decreased duration of sleep also increases heart rate, blood pressure and sympathetic activity magnifying the individual's response to stressful stimuli. Possible causal mechanisms for the established connection between short sleep cycles and coronary pathology include sympathetic nervous system hyperactivity, increased blood pressure increase or reduced glucose tolerance. Finally, sleep and fatigue have traditionally been linked. Fatigue can have a physical etiology but is also associated with depression. Sleep alterations are also considered an important risk factor for psychological dysfunction and also mental illness. However, despite the noted repercussions of sleep dysfunction, studies investigating interventions to improve sleep have been limited in number. Benefits of exercise programs on sleep habits have been controversial with some have finding positive effects, whereas others did not find any significant effect. It is possible that the dose or intensity of exercise programs may have an important influence in the outcomes. It is our opinion that based on the multi-system repercussions of different sleep dysfunctions, evaluation of sleep habits should be considered fundamental in the context of rehabilitation and should be included as part of the clinical history of each patient attending physical therapy.

Obstructive sleep apnea has been associated with a high risk for motor vehicle accidents, probably the highest of all risks due to medical conditions. Treatment of sleep apnea with nasal continuous positive airway pressure appears to reduce the risk of traffic accidents to the one of the general population. The risk for accidents may also be increased in untreated patients in the home and work environment. The increased risk seems unrelated to the symptom of daytime excessive sleepiness, and in many studies lacks a clear dose-response relationship with respect to the severity of apneas and hypopneas. The association of sleep apnea, chronic sleep deprivation and consumption of hypnotics or alcohol has not been thoroughly studied, although alcohol has been considered as a confounding variable in some studies. The cost of traffic accidents due to sleep apnea has been estimated to be so high that diagnosing and treating all drivers with sleep apnea in the USA would be cost saving and result in a decrease in society costs related to the disease. Driving licenses are delivered according to national legislations. These are all but uniform, especially concerning sleep apnea. Even within the European Union, where a minimum set of rules is mandatory for all countries, sleep apnea is not included in the minimum. Therefore, drivers are left in a very uncomfortable position, behaving according to the law in one country but being unlawful once the border with the neighbor country is crossed. Physicians are also in a very difficult position if they have to counsel their patients on the best attitude when travelling by car. The situation is even worse for commercial drivers, for whom the legislation is more severe but leaves sleep apnea uncovered in many countries. This is all the more disturbing if one considers that sleep apnea can be suspected, screened and diagnosed with relative ease, and that once diagnosed the adequate treatment allows for safe driving. The inclusion of sleep apnea in the European traffic license regulations would represent a step forward towards safe routes for patients and healthy people alike.

Obstructive sleep apnea (OSA) is a very frequent affliction that affects about 1-5% of the adult population in its severe form. Continuous positive airway pressure (CPAP) is the most commonly used treatment and is highly effective, but its use is limited by low long-term adherence rates and overall poor acceptance among the patients. Therefore, there is a need for developing alternative approaches to OSA treatment, including a more 'natural' concept of maintaining an open airway through neuromodulation. Here we review the concept, scientific rationale, and technical details of hypoglossal nerve stimulation. We also review results of published clinical studies with several hypoglossal stimulation devices that are being investigated today. Hypoglossal nerve stimulation appears to be a very promising treatment for patients with moderate-to-severe OSA. If its efficacy is confirmed, it will probably be complementary with CPAP therapy and initially aimed at patients unable or unwilling to use CPAP. Once it becomes a standard therapy, its advantages might prove sufficient to challenge CPAP as the first-line therapy.

" Fig.3), under the mucosal flap. The patient successfully restarted oral food intake and was discharged. Upper endoscopy and bronchoscopy confirmed the closure of the orifice during the subse- quent 8 months. There are currently multiple endoscopic options available for the treatment of tracheoesophageal fistulas, with an over- all success rate of 84% (1). Only one case report has described the use of mucosal resection (2). Biosynthetic mesh is fre- quently used in the surgical repair of multiple defects. However, endoscopic placement of mesh for tracheoesophageal fistula has only been described once, where it was deployed from the respira- tory tract and achieved a complete closure of the orifice (3). The case reported here describes a new endoscopic approach to tracheoesophageal fistulas that should be considered as an alternative in the man- agement of these challenging cases. Endoscopy_UCTN_Code_TTT_1AO_2AI

The intrapulmonary percussive ventilation (IPV), frequently coupled with a nebulizer, is increasingly used as a physiotherapy technique; however, its physiologic and clinical values have been poorly studied. The aim of this study was to compare lung deposition of amikacin by the nebulizer of the IPV device (Percussionaire; Percussionaire Corporation; Sandpoint, ID) and that of standard jet nebulization (SST; SideStream; Medic-Aid; West Sussex, UK). Amikacin was nebulized with both devices in a group of five healthy subjects during spontaneous breathing. The deposition of amikacin was measured by urinary monitoring. Drug output of both devices was measured. Respiratory frequency (RF) was significantly lower when comparing the IPV device with SST (8.2 +/- 1.6 breaths/min vs. 12.6 +/- 2.5 breaths/min, p < 0.05). The total daily amount of amikacin excreted in the urine was significantly lower with IPV than with SST (0.8% initial dose vs. 5.6% initial dose, p < 0.001). Elimination halflife was identical with both devices. Drug output was lower with IPV than with SST. The amount of amikacin delivered to the lung is sixfold lower with IPV than with SST, although a lower respiratory frequency was adopted by the subjects with the IPV. Therefore, the IPV seems unfavorable for the nebulization of antibiotics.

Continuous positive airway pressure (CPAP) remains the best treatment for sleep apnoea syndrome (SAS). In the 1990s, many authors reported on daily compliance, but all of the studies utilised relatively short periods of follow-up that did not exceed a few years. The mean annual rate of CPAP use in patients with SAS was prospectively recorded. In the current study, the results are presented along with compliance data from patients who started CPAP between 1991 and 1998 and were still using it by the end of 2003. The cohort was chosen in order to obtain >or=5 yrs of follow-up for each patient. In total, there were 204 patients. For the whole group, mean+/-sd compliance reached 321+/-90 and 393+/-84 min after 1 and 10 yrs, respectively. There was no significant change in the first 2 yrs, with a significant increase from the third year onwards. Compliance, or its evolution over time, was not correlated either to the baseline polysomnographical data (except slightly for the CPAP pressure), to the difference of these data before and under CPAP therapy, to the age of retirement or to changes in the marital status. In conclusion, very long-term compliance with continuous positive airway pressure increases by a mean of 8 min.day-1 per year of follow-up in patients with sleep apnoea syndrome.

OBJECTIVES: We compared, in a prospective study, the side effects and the postoperative complications of three procedures commonly used for the treatment of primary snoring. METHOD: Forty-nine patients underwent velopharyngeal surgery for primary snoring (17 for uvulopalatopharyngoplasty [UPPP]; 15 for laser-assisted uvulopalatoplasty [LAUP], and 17 for radiofrequency tissue volume reduction [RFTVR]). Preoperative full polysomnographic studies ruled out obstructive sleep apnea syndrome. Each patient's evaluation encompassed postoperative pharyngeal pain (as measured by a 5-point visual analogue scale) and use of narcotic drugs in the early postoperative period as well as a subjective evaluation of late postoperative complaints. A surgeon's examination was performed to report postoperative complications in the oropharynx. RESULTS: Postoperative pharyngeal pain was less important in the RFTVR group than in the UPPP and LAUP groups. Mean scores at days 3, 7, 16 were as follows: 4.2, 4.0, and 2.4, respectively, for UPPP; 4.6, 3.8, and 1.6 for LAUP; and 2.4, 2.0, and 0.7 for RFTVR. Mean duration of pain with a score greater than 2 was calculated as follows: UPPP, 21.3 days; LAUP, 15.1 days; and RFTVR, 6.1 days. Mean duration of narcotic drug use for the patients who needed this medication was 10.1 days for UPPP, 7.2 days for LAUP, and 1.3 for RFTVR. Postoperative side effects (trouble with smell and taste, pharyngeal dryness, globus sensation, voice change, and pharyngonasal reflux) were more present in the UPPP and LAUP groups than in the RFTVR group. Surgeon's assessment for postoperative complications reported more wound infection, dehiscence, and posterior pillar narrowing in the UPPP and LAUP groups than in the RFTVR group. CONCLUSION: RFTVR is a safer and less painful procedure than UPPP and LAUP for the treatment of primary snoring. Postoperative discomfort after LAUP and after UPPP appears to be very similar.

Rationale: Previous studies have shown that an increase in inspiratory pressure during nasal intermittent positive pressure ventilation (IPPV) does not result in increased effective minute ventilation ((V) over doe E) due to glottic interference. Study objectives: To test the consequences of increases in negative pressure ventilation (NPV) on (V) over dot E. Material and methods: Eight healthy awake subjects underwent NPV delivered by an iron lung. First, NPV was started at a respirator frequency (f) of 15 cycles per minute with an inspiratory negative pressure (INP) of - 15 cm H2O (F15-P15). Then,f was increased to 20 cycles per minute and INP was kept at - 15 cm H2O. Next,f was kept at 20 cycles per minute and INP was reduced to - 30 cm H2O (F20-P30). Finally,f was decreased to 15 cycles per minute and INP was kept at - 30 em H2O. At each step and for each breath, effective tidal volume (VT), (V) over dot E, and end-tidal carbon dioxide pressure were measured. In three subjects, the glottis width was assessed using fiberoptic bronchoseopy. Results: From spontaneous breathing to the first step of NPV (F15-P15), we observed an inhibition of the phasic inspiratory diaphragmatic electromyogram concomitant to a significant increase in (V) over dot E (p < 0.0005). For the group as a whole, the increase in mechanical ventilation (from F15-P15 to F20-P30) resulted in significant increases in VT and (V) over dot E leading to hypocapnia (p < 0.0005). Moreover, the glottis width did not decrease with the increase in mechanical ventilation. Conclusions: We conclude that in normal awake subjects, NPV allowed a significant increase in (V) over dot E. These results differ from those previously obtained with nasal IPPV in which the glottic width interferes with the delivered mechanical ventilation.

OBJECTIVE: To confirm the hypothesis that the ventilatory response to hypoxia (VRH) may be abolished by hypocapnia. METHODS: We studied four healthy subjects during intermittent positive-pressure ventilation delivered through a nasal mask (nIPPV). Delivered minute ventilation (Ed) was progressively increased to lower end-tidal carbon dioxide pressure (PETCO(2)) below the apneic threshold. Then, at different hypocapnic levels, nitrogen was added to induce falls in oxygen saturation, a hypoxic run (N(2) run). For each N(2) run, the reappearance of a diaphragmatic muscle activity and/or an increase in effective minute ventilation (E) and/or deformations in mask-pressure tracings were considered as a VRH, whereas unchanged tracings signified absence of a VRH. For the N(2) runs eliciting a VRH, the threshold response to hypoxia (TRh) was defined as the transcutaneous oxygen saturation level that corresponds to the beginning of the ventilatory changes. RESULTS: Thirty-seven N(2) runs were performed (7 N(2) runs during wakefulness and 30 N(2) runs during sleep). For severe hypocapnia (PETCO(2) of 27.1 +/- 5.2 mm Hg), no VRH was noted, whereas a VRH was observed for N(2) runs performed at significantly higher PETCO(2) levels (PETCO(2) of 34.0 +/- 2.1 mm Hg, p < 0.001). Deep oxygen desaturation (up to 64%) never elicited a VRH when the PETCO(2) level was < 29.3 mm Hg, which was considered the carbon dioxide inhibition threshold. For the 16 N(2) runs inducing a VRH, no correlations were found between PETCO(2) and TRh and between TRh and both Ed and E. CONCLUSION: During nIPPV, VRH is highly dependent on the carbon dioxide level and can be definitely abolished for severe hypocapnia.

Sleep apnoea is a condition in which people stop breathing during sleep. A number of studies in general and worker populations have shown that the prevalence of an apnoea-hypopnoea index (AHI) > 10 is in the range of 20%. Subjects with an AHI > 10 that complain of excessive daytime somnolence, tiredness, asphyxic episodes during the night or non-refreshing sleep, among other symptoms, suffer from the sleep apnoea hypopnoea syndrome (SAHS). The prevalence of SAHS is around 4%. Owing to its high prevalence, clinical symptoms, probable secondary cardiovascular consequences and associated social problems, SAHS has a considerable impact on health, management of which is worth considering. Despite the fact that SAHS treatment has been challenged recent studies conclude that nasal continuous positive airway pressure (nCPAP) is undoubtedly effective in clearly symptomatic patients. Its use in clinical practice is adequately supported in the treatment of moderate to severe SAHS. Further studies are needed in order to define the lower range of symptoms to be treated. One of the most important problems encountered in this area results from the combination of two situations. On the one hand, different epidemiological studies have demonstrated that an AHI > 10 without symptoms is present in around 15% of the general population. On the other hand, several studies suggest that having a high AHI, even without secondary symptoms, gives rise to some undesirable effects such as traffic accidents and cardiovascular consequences. In this context, comprehensive epidemiological studies are therefore warranted to define the role of nCPAP treatment especially in those subjects with a high AHI but with few or no symptoms. (C) 2002 Published by Elsevier Science Ltd.

The measurement of arousals during sleep is useful to quantify sleep fragmentation. The criteria for electroencephalography (EEG) arousals defined by the American Sleep Disorders Association (ASDA) have recently been criticized because of lack of interobserver agreement. The authors have adopted a scoring method that associates the increase in chin electromyography (EMG) with the occurrence of an α-rhythm in all sleep stages (Université Catholique de Louvain (UCL) definition of arousals). The aim of the present study was to compare the two scoring definitions in terms of agreement and repeatability and the time taken for scoring in patients with obstructive sleep apnoea syndrome (OSAS) of varying severity.Two readers using both ASDA and UCL definitions scored twenty polysomnographies (PSGs) each on two occasions. The PSGs were chosen retrospectively to represent a wide range of arousal index (from 6–82) in OSAS patients.There was no difference in the arousal indices between readers and between scoring methods. The mean±sd difference between the two definitions (the bias) was 1.1±3.76 (95% confidence interval: −0.66–2.86). There was a strong linear relationship between the arousal index scored with the two definitions (r=0.981, pversus25.3±6.6 min, pIn conclusion, it has been found that in obstructive sleep apnoea syndrome patients, the American Sleep Disorders Association and Université Catholique de Louvain definitions were comparable in terms of agreement and repeatability.

Obstructive sleep apnea syndrome (OSAS) is characterized by repetitive episodes of partial or complete obstruction of the upper airway during sleep. The obstruction predominantly occurs along the pharyngeal airway but other sites of obstruction have occasionally been described. We report our experience with three patients suffering from OSAS suspected to be of laryngeal origin. OSAS developed after reconstructive laryngectomy for glottic carcinoma and upper airway obstruction seemed to be located in the reconstructed laryngeal area. The three patients were given nCPAP (nasal-continuous positive airway pressure) treatment associated with peroral endoscopic CO2 laser vaporization of the laryngeal edema. After CO2 laser treatment, one patient was able to stop nCPAP treatment. The other two have remained on nCPAP therapy. OSAS may arise in the post-operative period of reconstructive laryngectomy for glottic carcinoma and can be managed by CO2 laser vaporization (laryngeal edema in the reconstructed area) in association with nCPAP treatment.

[Severe acute respiratory syndrome, avian influenza, the World Health Organization, and the Internet]

STUDY OBJECTIVES: The purpose of the present study was to compare in awake and asleep healthy subjects, under nasal intermittent positive pressure ventilation (nIPPV) with a two-level intermittent positive pressure device (two-level nIPPV), the efficacy of the controlled and spontaneous modes, and of different ventilator settings in increasing effective minute ventilation (VE). PARTICIPANTS: Eight healthy subjects were studied. SETTING: In the controlled mode, inspiratory positive airway pressure (IPAP) was kept at 15 cm H2O, expiratory positive airway pressure (EPAP) at 4 cm H2O, and the inspiratory/expiratory (I/E) time ratio at 1. The respirator frequencies were 17 and 25/min. In the spontaneous mode experiment, IPAP was started at 10 cm H2O and progressively increased to 15 and 20 cm H2O; EPAP was kept at 4 cm H2O. MEASUREMENTS AND RESULTS: We measured breath by breath the effective tidal volume (VT with respiratory inductive plethysmography), actual respiratory frequency (f), and effective VE. Using the controlled mode, effective VE was significantly higher on nIPPV than during spontaneous unassisted breathing, except in stage 2 nonrapid eye movement sleep at 17/min of frequency; increases in f from 17 to 25/min led to a significant decrease in VT reaching the lungs, during wakefulness and sleep; effective VE was higher at 25 than at 17/min of frequency only during sleep; periodic breathing was scarce and apneas were never observed. Using the spontaneous mode, with respect to awake spontaneous unassisted breathing, two-level nIPPV at 10 and 15 cm H2O of IPAP did not result in any significant increase in effective VE either in wakefulness or in sleep; only IPAP levels of 20 cm H2O resulted in a significant increase in effective VE; during sleep, effective VE was significantly lower than during wakefulness; respiratory rhythm instability (ie, periodic breathing and central apneas) were exceedingly common, and in some subjects extremely frequent, leading to surprisingly large falls in arterial oxygen saturation. CONCLUSIONS: It appears that two-level nIPPV should be used in the controlled mode rather than in the spontaneous mode, since it seems easier to increase effective VE with a lower IPAP at a high frequency than at a high pressure using the spontaneous mode. We suggest that the initial respirator settings in the controlled mode should be an f around 20/min, an I/E ratio of 1, 15 cm H2O of IPAP, and EPAP as low as possible.

In mechanically ventilated patients, pressure and flow tracings can be used to assess respiratory pump muscle activity or rest. When the ventilation is delivered through an endotracheal tube, the respiratory system can be considered a one-compartment model, and activation of the respiratory muscles results in deformations and variability of the pressure tracings. This is also true when mechanical ventilation is delivered nasally. With intermittent positive-pressure ventilation delivered through a nasal mask (nIPPV), we have recently shown that the glottis can interfere with ventilation even in the absence of diaphragmatic surface electromyographic (EMG) activity. On the basis of our observations, we suggested that when mechanical ventilation is delivered through a nasal means of access, the respiratory system cannot be considered a one-compartment model. To confirm this hypothesis, we submitted one healthy subject to nIPPV while his glottis was continuously monitored through a fiberoptic bronchoscope and his diaphragmatic activity was monitored with a bipolar esophageal electrode. During wakefulness or sleep, we observed irregularities in the nasal mask pressure waveform, in nasal mask peak pressure, and in actual VT despite the absence of respiratory pump muscle activity. These irregularities were related to significant variations in the glottic width, rather than to the reappearance of transient phasic inspiratory muscle activity. We conclude that during nIPPV, deformations in the mask pressure waveform can be induced by variations in the glottic aperture without activation of the diaphragm. Thus, when mechanical ventilation does not bypass the glottis, the respiratory system does not behave like a one-compartment model, and EMG remains the only reliable technique for assessing diaphragmatic muscle activity.

The aim of the present study was to assess whether nasal continuous positive airway pressure (nCPAP) treatment, applied for only a few hours at the beginning of the night, has any residual effect on sleep and breathing during the ensuing hours of unassisted sleep in patients with obstructive sleep apnoea syndrome (OSAS). In 27 patients with newly-diagnosed OSAS, effective nCPAP was applied during the first part of the night and then withdrawn. Polysomnographic parameters after nCPAP withdrawal were compared with those of the corresponding part of the diagnostic polysomnography performed a few days or weeks before and with those of the first part of night on nCPAP. After 255+/-63 (mean+/-SD) min of sleep with normalization of sleep and breathing parameters under nCPAP, there was partial improvement of OSAS severity during the remaining 124+/-56 min of nocturnal sleep without treatment; mean oxygen saturation, desaturation index (equivalent to the apnoea/hypopnoea index) and movement arousal index all improved significantly with respect to the diagnostic night (p=0.001). This improvement was not accounted for by a change in sleep architecture. We conclude that there is an improvement in severity of obstructive sleep apnoea syndrome after only 4 h of nasal continuous positive airway pressure. This carryover effect could explain why a number of patients with obstructive sleep apnoea syndrome apply nasal continuous positive airway pressure for only part of the night or not every night.

During a nocturnal dream, the authors discover a strange and unknown country, Absurdistan. Absurdistanis main concern appears to be sleep, whether nocturnal or diurnal, rather than wakefulness. They are fond of sleeping in any form, and devote much time to this activity. The authors follow a guide that shows them all kinds of strange sleep habits and keeps explaining the complex as well as the obvious. As the journey evolves, the explanations turn more and more confusing, becoming also amazingly surrealistic. The dream ends with a welcome wakefulness leaving the authors unsure of which is the waking state and which the dream.

Snoring, a symptom which may indicate the presence of the obstructive sleep apnoea syndrome (OSA), is also common in the general population. Recent studies have suggested that the acoustic characteristics of snoring sound may differ between simple snorers and OSA patients. We have studied a small number of patients with simple snoring and OSA, analysing the acoustic characteristics of the snoring sound. Seventeen male patients, 10 with OSA (apnoea/hypopnoea index (AHI) 26.2 events x h(-1)) and seven simple snorers (AHI 3.8 events x h(-1)), were studied. Full night polysomnography was performed and the snoring sound power spectrum was analysed. Spectral analysis of snoring sound showed the existence of two different patterns. The first pattern was characterized by the presence of a fundamental frequency and several harmonics. The second pattern was characterized by a low frequency peak with the sound energy scattered on a narrower band of frequencies, but without clearly identified harmonics. The seven simple snorers and two of the 10 patients with OSA (AIH 13 and 14 events x h(-1), respectively) showed the first pattern. The rest of the OSA patients showed the second pattern. The peak frequency of snoring was significantly lower in OSA patients, with all but one OSA patient and only one simple snorer showing a peak frequency below 150 Hz. A significant negative correlation was found between AHI and peak and mean frequencies of the snoring power spectrum (p

Sleep fragmentation (an increase in the number of short EEG arousals) is considered a major determinant of excessive daytime sleepiness but is seldom quantified in sleep studies, and reference values are scarce at best. We present data on the movement arousal index (MAI) in five groups of subjects: normals, simple snorers, patients with the sleep apnea-hypopnea syndrome (SAHS), and patients with sleep-related oxygen desaturations due to chronic obstructive pulmonary disease or neuromusculoskeletal disorders. In normal subjects, the MAI was 13 +/- 7 (mean +/- SD). MAI was distinctly increased in most patients with SAHS and was strongly correlated with the apnea-hypopnea index and loss of both slow wave and REM sleep. It was corrected to normal by nasal continuous positive airway pressure (CPAP). There was some overlap of MAI between SAHS patients and snorers, suggesting that a minority of nonapneic snorers may suffer from daytime sleepiness due to upper airway dysfunction. Sleep fragmentation is not a feature of sleep-related hypoventilation due to COPD or neuromusculoskeletal disorders, and an increase of the number of movement arousals (MA) is very suggestive of upper airway dysfunction and of potential success of CPAP. Quantification of sleep fragmentation is feasible and clinically useful; it should be included in the assessment of sleep-related breathing disorders.

Obstructive sleep apnoea is a chronic condition characterized by repetitive episodes of upper airway collapse during sleep, leading to sleep fragmentation. The management of sleep apnoea consists of general and specific measures. General measures should include weight loss in overweight patients; avoidance of alcohol during the evening hours; avoidance of any hypnotic drug. Specific measures may range from simple position training in patients with positional sleep apnoea (sleep apnoea appearing only when lying on the back) of slight severity; to oral appliances with the aim of creating a prognathism during sleep, to the introduction of a nasopharyngeal tube during sleep every night. When position training, oral appliances or a nasopharyngeal tube are used, their effect should be monitored by full night polysomnography. The best specific treatment for sleep apnoea is nasal continuous positive airway pressure. The main problem with nasal continuous positive airway pressure is the long-term compliance which should be assessed regularly over the years. In cases where nasal continuous positive airway pressure is not tolerated or compliance is bad, a surgical treatment can be proposed. Uvulopalatopharyngoplasty seems to give disappointing results. By contrast, maxillomandibular surgery is credited with the best results available as far as surgery is concerned, comparable to nasal continuous positive airway pressure.

We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.

Purpose: Sleep is commonly altered in critically ill patients. Ventilatory mode may impact on quality of sleep. The aim of our study was to evaluate the effect on sleep of pressure-controlled ventilation (PCV) to spontaneous ventilation with 6 cm H2O inspiratory pressure (low-PSV). Methods: Thirty-five patients intubated and mechanically ventilated for acute-on-chronic respiratory failure were included in this prospective randomized cross-over study. Nine were discarded, 13 received PCV first (10 p.m.-2 a.m.) and then low-PSV (2-6 a.m.) and 13 patients received low-PSV first and then PCV. Results: Sleep architecture was altered (50.4% of the night was spent in wakefulness). PCV was associated with significantly improved sleep quality and quantity compared to low-PSV: sleep efficiency (total sleep time/total recording time) was 63% (range: 9-100) vs. 37% (0-96; p = 0.0002), stage 2 NREM sleep was 33% vs. 13% (p = 0.0005), stages 3 and 4 NREM sleep were 9% vs. 3.5% (p = 0.003) and REM sleep was 6.5% vs. 0% (p = 0.003). Conclusions: Sleep quantity and quality were significantly improved with PCV compared to low-PSV. Nocturnal respiratory muscles rest through PCV is recommended to improve sleep in ICU patients with acute-on-chronic respiratory failure

Continuous positive airway pressure (CPAP) is an effective but cumbersome treatment for obstructive sleep apnoea (OSA). Noncompliant patients need alternative therapies. We studied a tongue neurostimulation approach: targeted hypoglossal neurostimulation (THN) therapy with the aura6000™ System. A multi-contact electrode positioned around the main trunk of the twelfth nerve connected to an implanted pulse generator stimulates segments of the nerve, activating dilator muscles. The primary objective was to improve the polysomnographically determined apnoea/hypopnoea index (AHI) at 3 months, and maintain the improvement after 12 months of treatment. 13 out of 14 operated patients were successfully implanted. At 12 months, the AHI decreased from 45±18 to 21±17, a 53% reduction (p

Background: Stable severe chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnic respiratory failure treated by nocturnal bi-level positive pressure non-invasive ventilation (NIV) may experience severe morning deventilation dyspnea. We hypothesised that in these patients, progressive hyperinflation, resulting from inappropriate ventilator settings, leads to patient-ventilator asynchrony (PVA) with a high rate of unrewarded inspiratory efforts and morning discomfort. Methods: Polysomnography (PSG), diaphragm electromyogram and transcutaneous capnography (PtcCO2) under NIV during two consecutive nights using baseline ventilator settings on the first night, then, during the second night, adjustment of ventilator parameters under PSG with assessment of impact of settings changes on sleep, patient-ventilator synchronisation, morning arterial blood gases and morning dyspnea. Results: Eight patients (61 ± 8 years, FEV1 30 ± 8% predicted, residual volume 210 ± 30% predicted) were included. In all patients, pressure support was decreased during setting adjustments, as well as tidal volume, while respiratory rate increased without any deleterious effect on nocturnal PtcCO2 or morning PaCO 2. PVA index, initially high (40 ± 30%) during the baseline night, decreased significantly after adjusting ventilator settings (p = 0.0009), as well as subjective perception of PVA leaks, and morning dyspnea while quality of sleep improved. Conclusion: The subgroup of COPD patients treated by home NIV, who present marked deventilation dyspnea and unrewarded efforts may benefit from adjustment of ventilator settings under PSG or polygraphy

Non-invasive ventilation (NIV) is recognised as an effective treatment for chronic hypercapnic respiratory failure. Monitoring NIV during sleep may be preferable to daytime assessment. This paper reports the findings of an international consensus group, which systematically analysed nocturnal polygraphic or polysomnographic tracings recorded with either volume-cycled or pressure-cycled ventilators. A systematic description of nocturnal respiratory events, which occur during NIV, is proposed: leaks, obstruction at different levels of the upper airway (glottis and/or pharynx), with or without decrease of respiratory drive and asynchrony.

The European Sleep Apnoea Database (ESADA) reflects a network of 22 sleep disorder centres in Europe enabled by a COST action B26 programme. This ongoing project aims to describe differences in standard clinical care of patients with obstructive sleep apnoea (OSA) and to establish a resource for genetic research in this disorder. Patients with suspected OSA are consecutively included and followed up according to local clinical standards. Anthropometrics, medical history, medication, daytime symptoms and sleep data (polysomnography or cardiorespiratory polygraphy) are recorded in a structured web-based report form. 5,103 patients (1,426 females, mean±SD age 51.8±12.6 yrs, 79.4% with apnoea/hypopnoea index (AHI) ≥5 events·h -1) were included from March 15, 2007 to August 1, 2009. Morbid obesity (body mass index ≥35 kg·m -2) was present in 21.1% of males and 28.6% of females. Cardiovascular, metabolic and pulmonary comorbidities were frequent (49.1%, 32.9% and 14.2%, respectively). Patients investigated with a polygraphic method had a lower AHI than those undergoing polysomnography (23.2±23.5 versus 29.1±26.3 events·h -1, p

We studied vocalization in 18 men with obstructive sleep apnea syndrome (OSAS) (age, 49 [7.5] years; body mass index [BMI] 33.6 [7.6]) and 10 normal men as a control group (age, 46.7 [6.2] years; BMI 24.6 [2.2]). Polysomnographic data for patients with OSAS were as follows: total sleep time (TST), 387.5 [27.9] min; awake, 17.6 (12.6% TST); stage 1, 19.8 (18.7 percent TST); stage 2, 54.8 (23.2 percent TST); stage 3 and 4, 1.5 (0.3 percent TST); and stage REM, 4.2 (1.7 percent TST). Apnea hypopnea index (AHI) was 43.0 (18.2) and lowest O2 saturation was 73.6 (11.4). We recorded the following sounds in all subjects: /a/ as in ''father''; /e/ as in ''get''; /i/ as in ''see''; /o/ as in ''go''; / u/ as in ''too.'' Three maneuvers for each vowel sound were taken for analysis. Signals were digitized at 10,000 Hz. Fast Fourier transformation was applied to segments of 512 points of each utterance corresponding to the vowel sound. The following parameters were obtained: maximum frequency of harmonics, mean frequency of harmonics, and the number of harmonics. Results: There were significant differences between both groups in the maximum frequency of harmonics of /i/ and /e/ vowels. (For /i/: 2,650 [672] Hz controls; 425 [71.2] Hz OSAS. For /e/: 2,605 [772.3] Hz controls; 1,250.0 [828.41 OSAS.) The number of harmonics for /i/ vowel was 4.5 (1.2) for controls as compared with 2.7 (1) Hz for OSAS. Conclusions: Vocalization in patients with OSAS is different from normal subjects. Vowel /i/ can distinguish these patients from normal subjects.

Compared with invasive ventilation, non-invasive ventilation (NIV) has two unique characteristics: the non-hermetic nature of the system and the fact that the ventilator-lung assembly cannot be considered as a single-compartment model because of the presence of variable resistance represented by the upper airway. When NIV is initiated, the ventilator settings are determined empirically based on a clinical evaluation and diurnal blood gas variations. However, NIV is predominantly applied during sleep. Consequently, to assess overnight patient-machine 'agreement' and efficacy of ventilation, more specific and sophisticated monitoring is needed. The effectiveness of NIV might therefore be more correctly assessed by sleep studies than by daytime assessment. The most available and simple monitoring can be done from flow and pressure curves from the mask or the ventilator circuit. Examination of these tracings can give useful information to evaluate if the settings chosen by the operator were the right ones for that patient. However, as NIV allows a large range of ventilatory parameters and settings, it is mandatory to have information about this to better understand patient-ventilator interaction. Ventilatory modality, mode of triggering, pressurisation slope, use or not of positive end expiratory pressure and type of exhalation as well as ventilator performances may all have physiological consequences. Leaks and upper airway resistance variations may, in turn, modify these patterns. This article discusses the equipment available for NIV, analyses the effect of different ventilator modes and settings and of exhalation and connecting circuits on ventilatory traces and gives the background necessary to understand their impact on nocturnal monitoring of NIV.

Study objectives: Hypercapnic ventilatory failure due to restrictive disorders may have a negative impact on sleep architecture. Non-invasive ventilation (NIV) may improve arterial blood gases but may adversely affect sleep. We assessed sleep structure and blood gases before and during NIV in patients with restrictive disorders in hypercapnic ventilatory failure. Design: Retrospective cohort study. Setting: Sleep laboratory of Saint-Luc University Hospital (Belgium). Patients: Chart review of all patients with predominantly restrictive disorders and respiratory failure seen between 1987 and 2008 and evaluated with a baseline polysomnography (PSG) and a PSG under NIV. Measurements and results: Sixty patients aged (mean±SD) 48±20years, with total lung capacity of 57±20% of predicted value, PaO 2 of 62±16mm Hg and PaCO 2 54±10mm Hg, were included. At baseline, total sleep time, sleep efficiency, slow wave and rapid-eye movement (REM) sleep were markedly decreased. Conversely, micro-arousals and stage I sleep (N1) were increased. NIV administered with volume-cycled (53%) or pressure-cycled (47%) ventilators improved daytime PaO 2 , PaCO 2 , pH and HCO 3 - . In addition, sleep efficiency, REM sleep, mean and lowest nocturnal SpO 2 increased while stage 1, sleep fragmentation, and oxygen desaturation index decreased significantly. Conclusion: Hypercapnic ventilatory failure in restrictive disorders profoundly affects sleep quality. NIV can improve not only blood gases, but also sleep architecture. © 2011 Elsevier B.V.

Contemporary homes can include a number of electrical devices aimed at making life easier, such as washing machines, dishwashers and vacuum cleaners. One can also find devices aimed at improving lifestyle, such as exercise bicycles or rowing machines. However, one can also find other types of devices that are aimed at supporting or saving people's life. These can include continuous positive airway pressure machines, home dialysis machines, oxygen concentrators and home respirators. All these devices have electrical plugs, knobs, switches, light bulbs, LEDs and screens. However, the manipulation of these devices is not at all similar, and the interactions between the devices and the users have quite different meanings. Despite the obvious differences between these machines, it remains true that a malfunctioning washing machine or a malfunctioning respirator will require a similar reaction: call the user support number. Respiratory physicians do not have a long tradition of home life support treatment and every piece of information concerning this issue is worth learning. In the present issue of the European Respiratory Journal , Chatwin et al. 1 present data on the call centre they established to support more than 1,000 patients on home respirators. The Respiratory Unit of the Royal Brompton Hospital (London, UK) serves a vast geographical area. In order to allow patients to reach them, they established a communication protocol based on telephone numbers patients can call day and night in case they need to or they feel they need to. These calls can be made for a number of reasons; from simple concerns such as asking for spare part replacement, to more disturbing ones such alarms coming on during the night or to a respirator becoming noisy all of a sudden, to very serious ones such as a respirator breakdown in a respirator dependent patient. Chatwin et al. …

Upper airway receptors are thought to contribute to upper airway stability by reducing collapsing forces. Their activity can be abolished by topical anesthesia. We have measured in 16 healthy volunteers (mean +/- SD age, 23.7 +/- 1.6 yr) specific airway conductance (SGaw), maximal inspiratory (MIFR) and expiratory (MEFR) flow rates before and 15, 35, and 45 min after extensive upper airway anesthesia (UAA) with 10% lidocaine. Average values of MIFR decreased (p less than 0.01) 15 min after UAA, but they returned to or near to control values at 45 min: MIF25 (4.8 versus 6.0 L/s); MIF50 (5.1 versus 6.2 L/s); MIF75 (4.4 versus 5.3 L/s). Transient decreases in flow (V) rates, reaching zero flow in some subjects, were observed in 13 subjects during forced inspiratory vital capacity (FIVC) maneuvers and in seven subjects during forced expiratory vital capacity (FEVC) maneuvers. MEFR at 25, 50, and 75% FVC, SGaw, and FVC did not change after anesthesia. Simultaneous measurements of supraglottic pressure, V, and lung volume in 12 of the 16 subjects showed that the site of flow limitation was localized at the level of the glottis in all except one subject in whom there was both a glottic and a supraglottic obstruction. We conclude that extensive upper airway anesthesia induced a profound but transitory upper airway obstruction during FIVC and FEVC maneuvers. These findings are compatible with the concept of reflex regulation of upper airway caliber.