Acute toxicity of total ammonia to Macrobrachium rosenbergii postlarvae at different salinity levels.

Nitrogen compounds, particularly ammonium, nitrite and nitrate, are a major problem in shrimp production systems. These compounds can accumulate in the aquatic environment and reach harmful or even lethal levels. Thus, monitoring the levels of nitrogenous compounds such as ammonia and studying their effects on the animals are essential. One tool used for this purpose is acute toxicity testing based on the evaluation of LC50 values. Furthermore, tools that can help improve the performance of aquatic organisms in culture are needed. The present study aimed to evaluate the effect of salinity on the toxicity of total ammonia to postlarvae of the freshwater prawn Macrobrachium rosenbergii. For this purpose, acute toxicity testing (LC50-96h) was performed using 540 postlarvae with a mean weight of 0.13 g and a mean total length of 2.47 cm, divided into 54 experimental units of two liters each. A completely randomized design in a 3×6 factorial scheme was used, combining three salinities (0, 5, and 10 g.L-1) and six total ammonia concentrations (0, 8, 16, 32, 64, and 128 mg.L-1), with three replicates per combination. The LC50 values for M. rosenbergii postlarvae at 24, 48, 72, and 96 h and their respective confidence intervals (95%) were estimated using the trimmed Spearman-Karber method. The results showed that salinities of 5 or 10 g.L-1 did not reduce the acute toxicity of total ammonia.

Growth differentiation factor 11 (GDF11) - a promising anti-ageing factor - is highly concentrated in platelets.

Recent research suggests that growth differentiation factor 11 (GDF11) could reverse age-related diseases and that its blood concentration decreases with age. This poses plasma from young donors as a therapeutic GDF11 source to treat age-related diseases. In addition, the tissue source of circulating GDF11 remains unknown. We analysed GDF11 levels in paired samples of serum, plasma and platelet lysate (PL) from 23 volunteers. Plasma and PL were collected by plateletpheresis. Here, we show that GDF11 is highly concentrated in platelets and that the circulating levels reported in previous studies could be biased as a result of serum sample manipulation.

Multi-site reproducibility of prefrontal-hippocampal connectivity estimates by stochastic DCM.

This study examined the reproducibility of prefrontal-hippocampal connectivity estimates obtained by stochastic dynamic causal modeling (sDCM). 180 healthy subjects were measured by functional magnetic resonance imaging (fMRI) during a standard working memory N-Back task at three different sites (Mannheim, Bonn, Berlin; each with 60 participants). The reproducibility of regional activations in key regions for working memory (dorsolateral prefrontal cortex, DLPFC; hippocampal formation, HF) was evaluated using conjunction analyses across locations. These analyses showed consistent activation of right DLPFC and deactivation of left HF across all three different sites. The effective connectivity between DLPFC and HF was analyzed using a simple two-region sDCM. For each subject, we evaluated sixty-seven alternative sDCMs and compared their relative plausibility using Bayesian model selection (BMS). Across all locations, BMS consistently revealed the same winning model, with the 2-Back working memory condition as driving input to both DLPFC and HF and with a connection from DLPFC to HF. Statistical tests on the sDCM parameter estimates did not show any significant differences across the three sites. The consistency of both the BMS results and model parameter estimates indicates the reliability of sDCM in our paradigm. This provides a basis for future genetic and clinical studies using this approach.

Bronchiectasis in primary Sjögren's syndrome: prevalence and clinical significance.

OBJECTIVES: To analyse the prevalence and clinical significance of bronchiectasis in a large series of patients with primary Sjögren's syndrome (SS) and evaluate its impact on disease expression and outcomes. METHODS: The study cohort included 507 patients with primary SS. Bronchiectasis were diagnosed according to pulmonary computed tomography (CT). As a control group, we included 37 consecutive SS patients evaluated by pulmonary CT during the same study period without pulmonary involvement. RESULTS: Fifty primary SS patients had bronchiectasis according to the pulmonary CT. Nine patients were excluded due to non-autoimmune processes and 41 were classified as bronchiectasis associated with primary SS (40 women, mean age of 64 years). All cases of bronchiectasis were of the cylindrical type and were located in the inferior lobes in 29 cases (71%). Patients with bronchiectasis were older at diagnosis of SS (60.39 vs. 52.54 years, p=0.022) and had a higher frequency of hiatus hernia (41% vs. 16%, p=0.024) in comparison with controls. Immunologically, patients with bronchiectasis had a lower frequency of anti-Ro/SS-A antibodies (27% vs. 54%, p=0.022) but a higher frequency of anti-smooth muscle--SMAantibodies (82% vs. 60%, p=0.043). During follow-up, patients with bronchiectasis had a higher frequency of respiratory infections (56% vs. 3%, p<0.001) and pneumonia (29% vs. 3%, p=0.002) in comparison with those without. CONCLUSIONS: Patients with primary SS and bronchiectasis are characterised by an older age, a high frequency of hiatus hernia, a specific immunologic pattern (low frequency of anti-Ro/SS-A and high frequency of anti-SMA) and during follow-up a much higher frequency of respiratory infections and pneumonia.

The linearity of emergent spectro-temporal receptive fields in a model of auditory cortex.

The responses of cortical neurons are often characterized by measuring their spectro-temporal receptive fields (STRFs). The STRF of a cell can be thought of as a representation of its stimulus 'preference' but it is also a filter or 'kernel' that represents the best linear prediction of the response of that cell to any stimulus. A range of in vivo STRFs with varying properties have been reported in various species, although none in humans. Using a computational model it has been shown that responses of ensembles of artificial STRFs, derived from limited sets of formative stimuli, preserve information about utterance class and prosody as well as the identity and sex of the speaker in a model speech classification system. In this work we help to put this idea on a biologically plausible footing by developing a simple model thalamo-cortical system built of conductance based neurons and synapses some of which exhibit spike-time-dependent plasticity. We show that the neurons in such a model when exposed to formative stimuli develop STRFs with varying temporal properties exhibiting a range of heterotopic integration. These model neurons also, in common with neurons measured in vivo, exhibit a wide range of non-linearities; this deviation from linearity can be exposed by characterizing the difference between the measured response of each neuron to a stimulus, and the response predicted by the STRF estimated for that neuron. The proposed model, with its simple architecture, learning rule, and modest number of neurons (<1000), is suitable for implementation in neuromorphic analogue VLSI hardware and hence could form the basis of a developmental, real time, neuromorphic sound classification system.

[Pulmonary varix inside a bulla]. / Variz pulmonar en el interior de una bulla.

Pulmonary varices are uncommon vascular abnormalities that are usually asymptomatic and so they are normally diagnosed by chance from a chest x-ray. They often present as a pulmonary nodule and can be either congenital or acquired. If acquired, they are associated with pulmonary venous hypertension, usually as a result of mitral valve disease. Pulmonary arteriography provides a definitive diagnosis, although the use of new noninvasive imaging techniques is spreading. Treatment is not normally required unless serious complications arise. We present the case of a pulmonary varix located within a pulmonary bulla. This form of presentation has not been previously reported.

Late detection of a shigellosis outbreak in a school in Madrid.

Even though shigellosis in Spain is rare, an indigenous outbreak is occasionally detected. We describe an outbreak in a school in Madrid caused by person-to-person transmission of Shigella sonnei. After the detection of Shigella sonnei in a stool sample from a 3 year old girl, an investigation at her school was initiated. Questionnaires were distributed to the parents of 520 pupils attending the school. A case was defined as a school case if it was the first case in a child's household, and as a household case if other members of the household had fallen ill first. We identified 88 cases (60 pupils and 28 of their family members). The attack rate (AR) was 12% in the school and 32% in the families. There was a significant association between higher AR and lower age. The outbreak lasted for two months. The length and the shape of the epidemic curve of the 60 cases in pupils suggests person-to-person transmission. Shigella sonnei isolated from 5 different cases were typed by pulsed field gel electrophoresis (PFGE) and was found to be an identical strain. The prolonged duration of the outbreak was probably due to delayed detection, and stopped as soon as control measures were introduced.

Mortality in Spain during the heat waves of summer 2003.

The effect of the elevated temperatures on mortality experienced in Europe during the summer of 2003 was observed in several countries. This study, carried out in Spain, describes mortality between 1 June and 31 August and evaluates the effect of the heat wave on mortality. Observed deaths were obtained from official death registers from 50 provincial capitals. Observed deaths were compared with the expected number, estimated by applying a Poisson regression model to historical mortality series and adjusting for the upward trend and seasonality observed. Meteorological information was provided by the Instituto Nacional de Meteorologia (National Institute of Meteorology). Spain experienced three heat waves in 2003. The total associated excess deaths were 8% (43 212 observed deaths compared with 40 046 expected deaths). Excess deaths were only observed in those aged 75 years and over (15% more deaths than expected for the age group 75 to 84 and 29% for those aged 85 or over). This phenomenon (heat-associated excess mortality) is an emerging public health problem because of its increasing attributable risk, the aging of the Spanish population and its forecasted increasing frequency due to global warming. The implementation of alert and response systems based on monitoring of climate-related risks, emergency room activity and mortality, and strengthening the response capacity of the social and health services should be considered.

Late detection of a shigellosis outbreak in a school in Madrid.

Even though shigellosis in Spain is rare, an indigenous outbreak is occasionally detected. We describe an outbreak in a school in Madrid caused by person-to-person transmission of Shigella sonnei. After the detection of Shigella sonnei in a stool sample from a 3 year old girl, an investigation at her school was initiated. Questionnaires were distributed to the parents of 520 pupils attending the school. A case was defined as a school case if it was the first case in a child's household, and as a household case if other members of the household had fallen ill first. We identified 88 cases (60 pupils and 28 of their family members). The attack rate (AR) was 12% in the school and 32% in the families. There was a significant association between higher AR and lower age. The outbreak lasted for two months. The length and the shape of the epidemic curve of the 60 cases in pupils suggests person-to-person transmission. Shigella sonnei isolated from 5 different cases were typed by pulsed field gel electrophoresis (PFGE) and was found to be an identical strain. The prolonged duration of the outbreak was probably due to delayed detection, and stopped as soon as control measures were introduced.

Mortality in Spain during the heat waves of summer 2003.

The effect of the elevated temperatures on mortality experienced in Europe during the summer of 2003 was observed in several countries. This study, carried out in Spain, describes mortality between 1 June and 31 August and evaluates the effect of the heat wave on mortality. Observed deaths were obtained from official death registers from 50 provincial capitals. Observed deaths were compared with the expected number, estimated by applying a Poisson regression model to historical mortality series and adjusting for the upward trend and seasonality observed. Meteorological information was provided by the Instituto Nacional de Meteorología (National Institute of Meteorology). Spain experienced three heat waves in 2003. The total associated excess deaths were 8% (43 212 observed deaths compared with 40 046 expected deaths). Excess deaths were only observed in those aged 75 years and over (15% more deaths than expected for the age group 75 to 84 and 29% for those aged 85 or over). This phenomenon (heat-associated excess mortality) is an emerging public health problem because of its increasing attributable risk, the aging of the Spanish population and its forecasted increasing frequency due to global warming. The implementation of alert and response systems based on monitoring of climate-related risks, emergency room activity and mortality, and strengthening the response capacity of the social and health services should be considered.

Laser-assisted uvulopalatoplasty for snoring: does it meet the expectations?

The high prevalence of habitual snoring (35% of the general population) and the increasing demand for an effective treatment have led, in the last decade, to the generalisation of laser-assisted uvulopalatoplasty (LAUP). However, acceptable studies on its effectiveness are lacking. The present randomised, placebo-controlled study included 25 nonapnoeic and mild obstructive sleep apnoea snorers to evaluate LAUP effectiveness for snoring. Group I received a one-stage LAUP treatment and group II a placebo (simulated snore surgery followed by an oral placebo). Before each treatment and 3 months after, the variables and procedures assessed were: body weight; sleepiness (Epworth sleepiness scale); quality of life (SF-36); subjective snoring intensity (0-10 analogue scale); objective snoring intensity (average decibel intensity); snoring index (number of snores per hour); and apnoea/hypopnea index. No differences were observed in body weight, sleepiness, quality of life, subjective and objective intensity, and frequency of snoring, and apnoea/hypopnea index between the groups before and 3 months after treatment. In conclusion, this study provides evidence of the lack of effectiveness of one-stage laser-assisted uvulopalatoplasty for snoring in nonapnoeic and mild obstructive sleep apnoea patients, with the result that it does not meet the expectations generated by the procedure.

Effectiveness of CPAP treatment in daytime function in sleep apnea syndrome: a randomized controlled study with an optimized placebo.

Application of continuous positive airway pressure (CPAP) as the standard treatment for sleep apnea/hypopnea syndrome (SAHS) is a moot point. Studies on the effectiveness of this treatment have been challenged because of the lack of a suitable placebo. The recent description of a true placebo (sham CPAP) prompted us to conduct a randomized trial of CPAP or placebo to assess the effectiveness of CPAP in improving SAHS-related symptoms and daytime function in patients with moderate to severe SAHS. Forty-eight patients, stratified in four groups according to severity, were randomly allocated into two treatment groups (optimal and sham CPAP) for a 6-wk period. Of these, 45 completed follow-up (91% males; age: 54 +/- 10 yr; body mass index [BMI]: 32 +/- 6 kg/m(2); apnea-hypopnea index [AHI]: 54 +/- 19 events/h; and Epworth Sleepiness Scale [ESS]: 16 +/- 5). The ESS, a questionnaire on SAHS-related symptoms, Functional Outcomes Sleep Questionnaire (FOSQ), and the Short Form Health Survey (SF-36) were completed at inclusion and after treatment. After 10 d of washout, the placebo group was treated with optimal CPAP and reassessed before and after optimal CPAP. The group receiving optimal CPAP when compared with the group with sham CPAP showed considerably greater improvement in the relief of sleepiness (-9.5 versus -2.3, p < 0.001), other SAHS-related symptoms (-18.5 versus -4.5, p < 0.001), vigilance (+8.5 versus +3.4, p = 0.009), and general productivity (+4.0 versus +0.5, p = 0.04) FOSQ scales. Both groups used a similar number of hours for the optimal and the sham CPAP (4.3 versus 4.5, (p = NS). The patients initially treated with placebo CPAP improved significantly more when optimal CPAP was applied for ESS (-2.3 versus -6.7, p < 0.001) and other sleep apnea syndrome (SAS)-related symptoms (-4.5 versus -11.2, p = 0.02). Our study provides strong evidence of the effectiveness of CPAP treatment in improving symptoms and perceived health status in moderate to severe SAHS.

[Benign sinusal mucor colonization in association with septal deviation]. / Colonización benigna sinusal por mucor asociada a desviación septal.

Mucormycosis is a well recognised opportunistic infection caused by saprophytic fungi of the Mucoraceae family. Usually, the upper aerodigestive tract is the portal of entry. Patients who are debilitated or inmunosuppressed might present with these infections, although sometimes can happen in patients with good health. We present a case of benign mucor colonitation at the sinus maxillary associated a deviated nasal septum.

Evaluation of a simplified oscillation technique for assessing airway obstruction in sleep apnoea.

The forced oscillation technique (FOT) is a noninvasive method that is useful for assessing airway obstruction and for titrating continuous positive airway pressure (CPAP) in patients with sleep apnoea. The aim was to evaluate the routine applicability of a simplified FOT set-up based on recording pressure and flow at the level of the CPAP device, i.e. obviating the need for connecting the transducers to the nasal mask. A correction to account for the tubing and the exhaust port was applied. This simplified FOT was evaluated on nine patients with moderate or severe sleep apnoea during routine CPAP titration. Patient impedance measured by the simplified FOT ([Z]) was compared with actual patient impedance ([Zrs]) measured simultaneously with a reference FOT based on recording pressure and flow at the nasal mask. An excellent agreement was found between [Z] and [Zrs] over the wide range of airway obstruction explored (4.8-72.1 cmH2O x s x L(-1)): [Z] = [Zrs] x 0.86 + 1.3 cmH2O x s x L(-1) (r = 0.99). Moreover, the simplified and the conventional FOT settings detected the same respiratory events during sleep. These results demonstrate that this simplified FOT is applicable for measuring airway obstruction during routine sleep studies in patients with sleep apnoea.

Development of a new flow-through bulk optode for the determination of manganese(III).

A flow-through bulk optode based on the use of 1-(2-pyridylazo)-2-naphthol (PAN) immobilized in a plasticized poly(vinyl chloride) membrane entrapped in a cellulose support, in conjuntion with the flow injection analysis technique, is proposed for the determination of manganese(II). The calibration graph obtained at 570 nm was linear in the range 0.27-27.5 mg L(-1) (5 x 10(-6)-5 x 10(-4) M) Mn(II) with a detection limit of 0.18 mg L(-1). The coefficients of variation of the sensor response for 5.5 mg L(-1) of Mn(II) were +/-0.22% for consecutive measurements (n = 10), +/-0.48% between days (n = 5) and +/-0.38% between different membranes (n = 6). The sensor was readily regenerated with the carrier acetic acid/acetate buffer of pH 4.5. The method was applied to the determination of manganese in steels, waters and lemon tree leaves.

Relevance of linearizing nasal prongs for assessing hypopneas and flow limitation during sleep.

Respiratory disturbances in patients with the sleep apnea-hypopnea syndrome (SAHS) may be detected by means of nasal prongs (NP) pressure (PNP). Nevertheless, PNP is nonlinearly related to flow (V). Our aim was to demonstrate the relevance of linearizing P NP for assessing hypopneas and flow limitation in SAHS. V was measured with a pneumotachograph during the hypopneas and flow limitation events in a continuous positive airway pressure (CPAP) titration in six patients with severe SAHS. These flow patterns were reproduced by a flow generator through an analog of the nares and recorded by NP. PNP was linearized [V NP = (PNP)1/2] by a specially designed analog circuit. For each event we used V, P NP, and V NP to compute the hypopnea flow amplitude (HFA) and a flow limitation index (FLI). Owing to NP nonlinearity, PNP considerably misestimated HFA and FLI. By contrast, V NP provided HFA and FLI values that were very close to those obtained from V: HFA (V NP) = 1.098. HFA(V) - 0.063 (r2 = 0.98) and FLI(V NP) = 1.044. FLI(V) + 0.004 (r2 = 0.99). Square-root linearization of NP greatly increases the accuracy of quantifying hypopneas and flow limitation. This procedure, which could be readily carried out in routine practice by means of the analog circuit we developed, is of interest in optimizing the assessment of respiratory sleep disturbances in SAHS.

Performance of nasal prongs in sleep studies : spectrum of flow-related events.

OBJECTIVES: The use of nasal prongs connected to a pressure transducer is a noninvasive, sensitive method to detect respiratory events, and can be easily implemented in routine sleep studies. Moreover, its good time response allows the detection of several flow-related phenomena of high interest, in addition to apnea and hypopnea. The aims of the study were to examine the quality and performance of the nasal prong flow signal, and to describe other flow-related events during full-night polysomnography studies. METHODS: Twenty-seven subjects were studied (16 male subjects; mean +/- SD age, 49 +/- 14 years; mean body mass index, 27 +/- 4 kg/m(2)): 15 subjects recruited from the general population and 12 consecutive patients with suspected sleep apnea/hypopnea syndrome (SAHS). RESULTS: A blind analysis of the respiratory events detected both by nasal prongs and thermistor was done. The quality of the nasal prong signal recordings was considered optimal for scoring purposes in 78% of cases, and no recording was considered uninterpretable. The nasal prong signal detected additional flow-related events not observed by the thermistor: (1) short and long (> 2 min) periods of inspiratory flow limitation morphology without decrease in the amplitude of the signal; (2) periods of mouth expiration; and (3) snoring. The apnea/hypopnea index was significantly higher with the nasal prong scoring (18 vs 11 [p < 0.05] in the general population and 37 vs 27 [p < 0.001] in the group with suspected SAHS). CONCLUSIONS: The incorporation of nasal prongs in routine full-night studies is an attainable technical option that provides adequate recordings in most cases. Additionally, relevant information not scored by thermistors is obtained on flow-related respiratory events, thus increasing diagnostic accuracy.

Evaluation of a portable respiratory recording device for detecting apnoeas and hypopnoeas in subjects from a general population.

This study was designed to validate a new home portable respiratory recording device (PRRD) to identify sleep apnoea and hypopnoea in a group of subjects (n=116), from a sample of the general population. Full night polysomnography (PSG) was used as the gold standard and simultaneously performed with PRRD. PRRD measurements included oronasal airflow (thermistry), chest wall impedance, oxygen saturation, snoring and body position. The sensors were unique for each recording system. Data obtained was blindly reviewed and analysed. A high level of agreement between both methods apnoea/hypopnoea index by PSG and the respiratory disturbance index (RDI) by PRRD was observed. Accuracy of the PRRD was evaluated in terms of sensitivity and specificity for different RDI-PRRD cut-off points with respect to AHI-PSG >10 and AHI-PSG >30. A logistic regression model was performed to estimate the chance per unit of RDI of apnoeas. A received operating characteristic (ROC) curve was drawn to obtain the sensitivity/specificity profile for each observed RDI value obtained. From the ROC curve the authors identified the better cut-off points, which represent a balanced sensitivity/specificity. Through a classification table defined by the cut-off point, the post-odds to exhibit the disease was calculated. For a full PSG cut-off point of 10 a PRRD of six showed a balanced sensitivity of 95% and a specificity of 92%. For a full PSG cut-off point of 30 a PRRD of 16 shows a balanced sensitivity/specificity (100% and 97%, respectively). Post odds of apnoea were calculated for each cut-off point. In conclusion, these data suggest that the portable respiratory recording device is an effective device to identify apnoeas and hypopnoeas in a general population and is therefore a suitable device to be used in epidemiological studies.

Time course of sleep-related breathing disorders in first-ever stroke or transient ischemic attack.

To investigate the prevalence and behavior of sleep-related breathing disorders (SRBDs) associated with a first-ever stroke or transient ischemic attack (TIA), we prospectively studied 161 consecutive patients admitted to our stroke unit. Complete neurological assessment was performed to determine parenchymatous and vascular localization of the neurological lesion. Stroke subtype was categorized as TIA, ischemic (IS), or hemorrhagic (HS). A portable respiratory recording (PRR) study was performed within 48-72 h after admission (acute phase), and subsequently after 3 mo (stable phase). During the acute phase, 116 patients (71.4%) had an apnea-hypopnea index (AHI) > 10 events/h and 45 (28%) had an AHI > 30. No relationships were found between sleep-related respiratory events and the topographical parenchymatous location of the neurological lesion or vascular involvement. Cheyne-Stokes breathing (CSB) was observed in 42 cases (26.1%). There were no significant differences in SRBD according to the stroke subtype except for the central apnea index (CAI). During the stable phase a second PRR was performed in 86 patients: 53 of 86 had an AHI > 10 and 17 of 86 had an AHI > 30. The AHI and CAI were significantly lower than those in the acute phase (16.9 +/- 13.8 versus 22.4 +/- 17.3 and 3.3 +/- 7.6 versus 6.2 +/- 10.2, respectively) (p < 0.05) while the obstructive apnea index (OAI) remained unchanged. CSB was observed in 6 of 86 patients. The prevalence of SRBD in patients with first-ever stroke or TIA is higher than expected from the available epidemiological data in our country. No correlation was found between neurological location and the presence or type of SRBD. Obstructive events seem to be a condition prior to the neurological disease whereas central events and CSB could be its consequence.

Clinical application of the forced oscillation technique for CPAP titration in the sleep apnea/hypopnea syndrome.

We have previously demonstrated that upper airway obstruction in sleep apnea/hypopnea syndrome (SAHS) can be accurately assessed in real-time by measuring respiratory impedance (|Z|) with the forced oscillation technique (FOT). The aims of the present study were: (1) to determine the feasibility of identifying the optimal continuous positive airway pressure (CPAP) for patients with SAHS based on analysis of the |Z| signal during conventional polysomnographic CPAP titration studies; and (2) to evaluate practical issues involved in the application of FOT during CPAP titration. We performed CPAP titration in 28 patients with SAHS during polysomnography (PSG) (14 nap and 14 full overnight studies) using a FOT system applied continuously to obtain an on-line measurement of |Z|. FOT was easily implemented and was well-tolerated by the patients. Optimal CPAP levels were determined both in the conventional manner from the standard PSG titration record and during a separate blinded analysis using the FOT signal alone. The mean conventional versus FOT-based optimal CPAP values were similar for both nap studies (10.6 +/- 0.6 [mean +/- SEM] versus 11.1 +/- 0.6 cm H(2)O, respectively, p = 0. 054) and overnight studies (9.9 +/- 0.7 versus 9.9 +/- 0.6 cm H(2)O, respectively, p = 1.00). Subsequent analysis of the PSG record with the FOT signal incorporated demonstrated that artefacts in the |Z| tracing occurred during mask leak, mouth breathing, and movement during arousal. Such abnormalities were readily identified from the flow tracing. These results indicate that, for adequate interpretation, the tracing and values of respiratory impedance obtained by FOT should be evaluated in conjunction with the flow signal. Continuous FOT-guided CPAP titration is feasible and may be a useful adjunct during manual titration. FOT could also potentially serve as the basis for automated CPAP in SAHS.