Proof of principle study: diagnostic accuracy of a novel algorithm for the estimation of sleep stages and disease severity in patients with sleep-disordered breathing based on actigraphy and respiratory inductance plethysmography.

PURPOSE: In this proof of principle study, we evaluated the diagnostic accuracy of the novel Nox BodySleepTM 1.0 algorithm (Nox Medical, Iceland) for the estimation of disease severity and sleep stages based on features extracted from actigraphy and respiratory inductance plethysmography (RIP) belts. Validation was performed against in-lab polysomnography (PSG) in patients with sleep-disordered breathing (SDB). METHODS: Patients received PSG according to AASM. Sleep stages were manually scored using the AASM criteria and the recording was evaluated by the novel algorithm. The results were analyzed by descriptive statistics methods (IBM SPSS Statistics 25.0). RESULTS: We found a strong Pearson correlation (r=0.91) with a bias of 0.2/h for AHI estimation as well as a good correlation (r=0.81) and an overestimation of 14 min for total sleep time (TST). Sleep efficiency (SE) was also valued with a good Pearson correlation (r=0.73) and an overestimation of 2.1%. Wake epochs were estimated with a sensitivity of 0.65 and a specificity of 0.59 while REM and non-REM (NREM) phases were evaluated a sensitivity of 0.72 and 0.74, respectively. Specificity was 0.74 for NREM and 0.68 for REM. Additionally, a Cohen's kappa of 0.62 was found for this 3-class classification problem. CONCLUSION: The algorithm shows a moderate diagnostic accuracy for the estimation of sleep. In addition, the algorithm determines the AHI with good agreement with the manual scoring and it shows good diagnostic accuracy in estimating wake-sleep transition. The presented algorithm seems to be an appropriate tool to increase the diagnostic accuracy of portable monitoring. The validated diagnostic algorithm promises a more appropriate and cost-effective method if integrated in out-of-center (OOC) testing of patients with suspicion for SDB.

Stimuli used in the measurement of problematic sexual interests.

Penile plethysmography (PPG) is the primary physiologic assessment method used to gauge sexual responses in adult men. Depending on the country or jurisdiction of assessment, stimuli used to elicit arousal can include videos, still images, and audio materials. It can depict a variety consenting and non-consenting sexual scenarios as well as neutral, non-sexual scenarios. Models in visual stimuli can be clothed, semi-clothed, or nude. Variation in stimuli modality and the type of sexual interest being tested can have a large impact on PPG outcomes. This paper reviews research on types of PPG stimuli, the different sexual interests being assessed, reliability and validity, and the impact of anonymizing models depicted in assessment materials. Innovations in stimuli development in three labs located in Canada, the United States, and the Czech Republic are also discussed. The work done in these three labs and the broader range of research on assessment stimuli are presented to highlight the need for a unified, multi-site, standardized approach to assess problematic sexual interests and their change in response to treatment.

Exploring the source of short-term variations in respiratory data.

This study explores short-term respiratory volume changes in German oral and nasal stops and discusses to what extent these changes may be explained by laryngeal-oral coordination. It is expected that respiratory volumes decrease more rapidly when the glottis and the vocal tract are open after the release of voiceless aspirated stops. Two experiments were performed using Inductance Plethysmography and acoustics, varying consonantal properties, loudness, and prosodic focus. Results show consistent differences in respiratory slopes between voiceless vs voiced and nasal stops, which are more extreme in a loud or focused position. Thus, respiratory changes can even occur at a local level.

Comparing DXA and Air Displacement Plethysmography to Assess Body Composition of Male Collegiate Hockey Players.

Delisle-Houde, P, Reid, RER, Insogna, JA, Prokop, NW, Buchan, TA, Fontaine, SL, and Andersen, RE. Comparing DXA and air-displacement-plethysmography to assess body composition of male collegiate hockey players. J Strength Cond Res 33(2): 474-478, 2019-Accurate assessment of body composition is an important consideration for athletes because it is a health/performance variable. However, little is known about the variability in values obtained across different assessment methods for specific athlete populations. The purpose of this study was to compare 2 common laboratory methods that assess body composition: air displacement plethysmography (BOD POD) and dual energy x-ray absorptiometry (DXA). Twenty-nine male collegiate hockey players, (Age = 24.07 ± 1.49, BMI = 26.5 ± 2.74) participated in this study. All participants underwent back-to-back BOD POD and DXA evaluations. Paired t-tests and Bland-Altman analyses were performed to compare differences in fat mass, fat percentage, and fat-free mass between methods. Average fat percentage reported by the DXA and BOD POD was 15.34 ± 3.53 and 11.66 ± 4.82 respectively, resulting in a bias score of 3.78 ± 2.33 kg (t(28) = 8.71, p ≤ 0.001). Average fat mass reported by the DXA and BOD POD was 13.42 ± 3.59 and 10.15 ± 4.54 kg respectively, resulting in a bias score of 3.27 ± 1.92 kg (t(28) = 9.18, p ≤ 0.001). Average fat-free mass reported by the DXA and BOD POD was 73.31 ± 5.30 and 76.25 ± 5.74 kg respectively, resulting in a bias score of -2.93 ± 2.06 kg (t(28) = -7.66, p ≤ 0.001). Our findings can help make more insightful comparisons between studies that use different body composition methodologies among athletic populations.

The airway hyperresponsiveness to methacholine may be predicted by impulse oscillometry and plethysmography in children with well-controlled asthma.

OBJECTIVE: Airway hyperresponsiveness (AHR) is a hallmark of asthma. Methacholine challenge test which is mostly used to confirm AHR is not routinely available. The aim of this study was to investigate the predictive values of fractional exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and plethysmography for the assessment of AHR in children with well-controlled asthma. METHODS: 60 children with controlled allergic asthma aged 6-18 years participated in the study. FeNO measurement, spirometry, IOS, and plethysmography were performed. Methacholine challenge test was done to assess AHR. PC20 and dose response slope (DRS) of methacholine was calculated. RESULTS: Mild to severe AHR with PC20 < 4 mg/ml was confirmed in 31 (51.7%) patients. Baseline FeNO and total specific airway resistance (SRtot)%pred and residual volume (RV)%pred levels in plethysmography were significantly higher and FEV1%pred, FEV1/FVC%pred, MMEF%pred values were lower in the group with PC20 < 4 mg/ml. FeNO, SRtot%pred, and RV%pred levels were found to be positively correlated with DRS methacholine. The higher baseline FeNO, frequency dependence of resistance (R5-R20) in IOS and SRtot%pred in plethysmography were found to be significantly related to DRS methacholine in linear regression analysis (ß: 1.35, p = 0.046, ß: 4.58, p = 0.002, and ß: 0.78, p = 0.035, respectively). The cut-off points for FeNO and SRtot% for differentiating asthmatic children with PC20 < 4 mg/ml from those with PC20 ≥ 4 mg/ml were 28 ppb (sensitivity: 67.7%, specificity: 72.4%, p < 0.001) and 294.9% (sensitivity: 35.5%, specificity: 96.6%, p = 0.013), respectively. CONCLUSION: IOS and plethysmography may serve as reliable and practical tools for prediction of mild to severe methacholine induced AHR in otherwise "seemingly well-controlled'' asthma.

Venous occlusion plethysmography vs. Doppler ultrasound in the assessment of leg blood flow kinetics during different intensities of calf exercise.

PURPOSE: It has recently been shown that venous occlusion plethysmography (VOP) can successfully assess the rate of increase in leg blood flow (LBF) (LBF kinetics) responses during calf exercise, but there is lack of data supporting its validity. METHODS: Using Doppler ultrasound (DU) as a criterion standard technique, we tested the hypothesis that VOP would provide similar estimates of LBF kinetics responses as DU during calf plantar-flexion exercise at a range of different intensities. Ten healthy men performed repeated intermittent calf plantar-flexion contractions (3 s duty cycles, 1 s contraction/2 s relaxation) at 30, 50 and 70% maximum voluntary contraction (MVC) on different days. RESULTS: Resting LBF values were significantly (P < 0.05) larger for DU than VOP but the overall mean LBF responses during exercise were not different (P > 0.05) between DU and VOP (30% MVC: 330 ± 78 vs. 313 ± 92 ml/min; 50% MVC: 515 ± 145 vs. 483 ± 164 ml/min; 70% MVC: 733 ± 218 vs. 616 ± 229 ml/min). LBF kinetics analyses revealed that the end-amplitude at the highest intensity (70% MVC) was significantly higher when measured by DU compared with VOP, but all other kinetics parameters were not different between VOP and DU. CONCLUSIONS: Given that these slight differences in amplitude observed during exercise can be explained by differences in vascular regions which the two techniques assess, our results suggest that VOP can accurately assess LBF kinetics responses during calf plantar-flexion exercise at intensities between 30 and 70% MVC.

Standardised noxious stimulation-guided individual adjustment of remifentanil target-controlled infusion to prevent haemodynamic responses to laryngoscopy and surgical incision: A randomised controlled trial.

BACKGROUND: The surgical plethysmographic index (SPI) is one of the available indexes of the nociception-antinociception (NAN) balance. Individually adjusting the NAN balance to prevent somatic responses to noxious stimulation remains a challenge. OBJECTIVES: To assess whether guiding remifentanil administration according to the SPI response to a calibrated noxious stimulus (NANCAL) can blunt the haemodynamic response to tracheal intubation and surgical incision. DESIGN: Randomised multicentre study. SETTING: Two Belgian university hospitals from January 2014 to April 2015. PATIENTS: After ethic review board approval and informed consent, 48 American Society of Anesthesiologists I or II adult patients scheduled for surgery under general anaesthesia were enrolled. INTERVENTIONS: Patients were randomly assigned to a SPI group, where remifentanil effect-site concentration was adjusted according to NANCAL, or a control group, where it was fixed at 4 ng ml. Propofol concentration was always adjusted to maintain the bispectral index close to 40. NANCAL consisted of a 100 Hz, 60 mA electrical tetanic stimulation during 30 s at the wrist before tracheal intubation and before surgical incision. MAIN OUTCOME MEASURES: The primary endpoint was the efficacy of the NANCAL-guided remifentanil administration to prevent the haemodynamic response to tracheal intubation and surgical incision. The secondary aim was to compare the ability of SPI, analgesia nociception index, pupil diameter and mean arterial pressure response to NANCAL to predict the haemodynamic response to tracheal intubation and surgical incision. RESULTS: Our SPI response to NANCAL-based correcting scheme for remifentanil administration was not superior to a fixed remifentanil concentration at blunting the haemodynamic response to tracheal intubation or surgical incision. Among all tested NAN balance indices, only mean arterial pressure had significant predictive ability with regard to the haemodynamic response to surgical incision. CONCLUSION: Further research is needed to define the best NANCAL stimulus and the best remifentanil correcting scheme to help individualised tailoring of antinociception for each specific subpopulation of surgical patients. TRIAL REGISTRATION: Clinicaltrials.gov NCT: 02884310; https://clinicaltrials.gov/ct2/show/NCT02884310.

Reference data for BabyBody-plethysmographic measurements in Chinese neonates and infants.

BACKGROUND AND OBJECTIVE: Population-specific pulmonary function reference data are essential to identify the nature and severity of respiratory diseases. However, there is a lack of reference data for Chinese neonates and infants. The objective of this study was to develop reference data for tidal breathing and plethysmographic measurements for Chinese subjects during the first 2 years of life. METHODS: Data of tidal breathing and plethysmography from healthy Chinese neonates (≤28 days) and infants (1-24 months) using the Jaeger MasterScreen BabyBody were collated. All subjects were sedated for the tests. Multivariable analyses were performed to determine predictive variables for the pulmonary function parameters. Reference equations for outcomes were constructed using multilevel modelling and the LMS (lambda-mu-sigma) method was used for establishing smoothed reference percentiles. RESULTS: Four hundred and ten healthy subjects were tested. Acceptable measurements of tidal breathing analysis and plethysmography outcomes were obtained in 396 (96.6%) and 370 (90.4%) subjects, respectively. Normal reference percentiles and equations for the main parameters of tidal breathing and plethysmography were derived from test occasions of 211 neonates and 185 infants. Body weight, crown-heel length and age were significantly associated with lung function, of which length was the strongest predictor. CONCLUSION: This study provides reference data of BabyBody-plethysmographic measurements for healthy Chinese subjects in their first 2 years of life. Weight and length are the strongest predictors for neonatal and infant lung function, respectively.

Assessment of problematic sexual interests with the penile plethysmograph: an overview of assessment laboratories.

Phallometric testing, or penile plethysmography (PPG), is an objective measure of sexual arousal for males. While extensive research on the reliability and validity of PPG has promoted its reputation as the "gold standard" of objective measurement of sexual arousal, there is a lack of standardization of stimulus sets and interpretation of results between sites. This article describes the laboratory protocol employed for PPG at the Royal Ottawa Mental Health Centre's Sexual Behaviours Clinic (SBC) in Ottawa, Ontario, as well as those used by the Sexual Behaviors Clinic and Lab (SBCL) in the Community and Public Safety Psychiatry Division (CPSPD) of the Department of Psychiatry and Behavioral Sciences at Medical University of South Carolina (MUSC) in Charleston, South Carolina. The need for standardization in both testing protocol and stimuli use across sites are highlighted.

A wearable respiratory monitoring device--the between-days variability of calibration.

The between-days variability in ascertained gain factors for calibration of a wearable respiratory inductance plethysmograph (RIP) and validity thereof for the repeated use during exercise were examined. Consecutive 5-min periods of standing still, slow running at 8 km·h(-1), fast running at 14 km·h(-1) (male) or 12 km·h(-1) (female) and recovery were repeated by 10 healthy subjects on 5 days. Breath-by-breath data were recorded simultaneously by flow meter and RIP. Gain factors were determined individually for each trial (CALIND) via least square regression. Reliability and variability in gain factors were quantified respectively by intraclass correlation coefficients (ICC) and limits of agreement. Within a predefined error range of ±20% the amount of RIP-derived tidal volumes after CALIND was compared to corresponding amounts when gain factors of the first trial were applied on the following 4 trials (CALFIRST). ICC ranged within 0.96 and 0.98. The variability in gain factors (up to ± 24.06%) was reduced compensatively by their sum. Amounts of breaths within the predefined error range did not differ between CALIND and (CALFIRST) (P>0.32). The between-days variability of gain factors for a wearable RIP-device does not show impaired reliability in further derived tidal volumes.

Computerized venous strain-gauge plethysmography is a reliable method for measuring venous function.

OBJECTIVES: To achieve reference values for computerized strain-gauge plethysmography (SGP), to assess reproducibility, and to evaluate the influence of different factors such as age, gender, body mass index, and symptomatic post-thrombotic disease on commonly used variables. METHODS: Sixty-three healthy controls and 56 patients with previous deep venous thrombosis (DVT) were included. All participants underwent computerized SGP with evaluation of outflow capacity, as well as evaluation of venous reflux and muscle pump function. RESULTS: All variables were significantly reduced in DVT limbs, both compared with contralateral limbs and with healthy controls. Only two patients had all values within normal ranges (=mean ± 2 SD in controls). Measures of outflow capacity had a coefficient of variation (CV) of 5-6% and exercise-induced volume changes a CV of 10-15%. In symptomatic post-thrombotic limbs half-refilling time was significantly related to presence of edema (R = -0.28, p < .05) and to chronic skin changes (R = -0.58, p < .001). CONCLUSIONS: We suggest that our values in healthy controls can be used as new reference values for computerized venous strain-gauge plethysmography. The computerized design ensures high reproducibility and the results indicate that this is a very useful and sensitive test for functional quantitative assessment of patients with venous disease.

Test-retest reliability of the Bod Pod: the effect of multiple assessments.

The Bod Pod uses air-displacement plethysmography to estimate body fat percentage (BF%). This study was designed to assess the test-retest reliability of the Bod Pod. The study included 283 women (M age = 41.0 yr., SD = 3.0). Each participant was tested at least twice in the Bod Pod. Results showed no significant mean difference between the test and the retest. The intraclass correlation coefficient (ICC) was .991. However, the absolute value of the initial trial differences (absolute mean difference) was .96 (SD = .90). A third assessment of BF% was taken when the initial trial difference was greater than 1 percentage point, and the two closest values were compared. This strategy resulted in a significant decrease in the absolute mean difference, from .96 to .55 percentage point, and ICC increased to .998. The Bod Pod appears to measure body fat percentage reliably; however, findings suggest that multiple trials may be necessary to detect small treatment effects.

Evaluation of cardiac output in intensive care using a non-invasive arterial pulse contour technique (Nexfin(®)) compared with echocardiography.

In this prospective study, cardiac output was measured in 38 intensive care unit patients before and after a fluid challenge, using both pulse contour analysis (Nexfin(®); BMEYE, Amsterdam, the Netherlands) and transthoracic echocardiography. The ability of the Nexfin device to detect significant changes in the velocity-time integral was evaluated. The pulse wave could not be detected by the Nexfin device in five patients (13%), leaving 33 patients for analysis. The Nexfin device adequately tracked changes in the velocity-time integral in 20 (61%) patients. Using a cut-off of a 10% increase in cardiac output estimated by the Nexfin or by echocardiography, the sensitivity of the Nexfin device to detect a response to fluid challenge was 47%, with specificity 81% and accuracy 64%. The percentage error between the Nexfin and echocardiography was 448%; lower limit of agreement -48% (95% CI -62 to -36%) and upper limit of agreement, 32% (95% CI 20-45%). We conclude that the Nexfin device does not adequately track changes in cardiac output in critically ill patients.

Perfusion index and its dynamic changes in preterm neonates with patent ductus arteriosus.

AIM: The perfusion index (PI) and its dynamic change during respiration, and supressed the plethysmographic variability index (PVI), are calculated from pulse oximetry, and these indexes were recently proposed for continuous and noninvasive assessment of peripheral perfusion in neonates. We aimed to assess the effect of patent ductus arteriosus (PDA) on PI and PVI, according to ductal Doppler flow pattern. METHODS: Forty-five neonates with median (Q25-75) gestational age (GA) and birthweight of 27 (25-28) weeks and 857 (750-1080) grams, respectively, were assessed prospectively using serial echocardiography and pulse oximetry during the first postnatal week. RESULTS: Perfusion index increased from 0.70 (0.50-1.05) at day 1 to 1.50 (1.0-2.00) at day 7 (p < 0.01) and was not influenced by ductal flow pattern. PVI was 22 (18-27) and did not vary during the study period but differed according to ductal flow pattern, with lower values in the growing and pulsatile groups compared with the pulmonary hypertension (p < 0.05), closing and closed groups (p < 0.01). CONCLUSIONS: Ductal persistence and flow pattern did not affect PI but did affect PVI in preterm neonates of less than 29 weeks of GA. Future studies are needed to establish the usefulness of PVI in the early detection and management of PDA in preterm neonates.

Plethysmographic variability index (PVI) accuracy in predicting fluid responsiveness in anesthetized children.

INTRODUCTION: Plethysmographic Variability Index (PVI) has been shown to accurately predict responsiveness to fluid loads in adults. The goal of this study was to evaluate PVI accuracy when predicting fluid responsiveness during noncardiac surgery in children. MATERIAL AND METHODS: Children aged 2-10 years scheduled for noncardiac surgery under general anesthesia were included. PVI was assessed concomitantly with stroke volume index (SVI). A response to fluid load was defined by an SVI increase of more than 15%. A 10 ml·kg(-1) normal saline intravenous fluid challenge was administered before surgical incision and after anesthetic induction. After incision, fluid challenges were administered when SVI values decreased by more than 15% or where judged necessary by the anesthesiologist. Statistical analyses include receiving operator characteristics (ROC) analysis and the determination of gray zone method with an error tolerance of 10%. RESULTS: Fifty-four patients were included, 97 fluid challenges administered and 45 responses recorded. Area under the curve of ROC curves was 0.85 [0.77-0.93] and 0.8 [0.7-0.89] for baseline PVI and SVI values, respectively. Corresponding gray zone limits were [10-17%] and [22-31 ml·m(-2)], respectively. PVI values exhibited different gray zone limits for pre-incision and postincision fluid challenges, whereas SVI values were comparable. PVI value percentages in the gray zone were 34% overall and 44% for challenges performed after surgical incision. DISCUSSION: This study found both PVI and prechallenge SVI to be accurate when used to predict fluid load response during anesthetized noncardiac surgery in children. However, a third of recorded PVI values were inconclusive.

Digital orbitoplethysmograph: A new device to study the regional cerebral circulation using extraorbital plethysmography.

BACKGROUND: Noninvasive diagnostic methods utilizing pulse wave measurements on the surface of the head are an important tool in diagnosing various types of cerebrovascular disease. The measurement of extraorbital pressure fluctuations reflects intraocular and intracranial pressure changes and can be used to estimate pressure changes in intracranial arteries and the collateral circulation. NEW METHOD: In this paper, we describe our patented (CZ 305757) digital device for noninvasive measuring and monitoring of orbital movements using pressure detection. We conducted preclinical tests (126 measurements on 42 volunteers) to evaluate the practical capabilities of our device. Two human experts visually assessed the quality of the pressure pulsation and discriminability among various test conditions (specifically, subject lying, sitting, and the Matas carotid occlusion test). RESULTS: The results showed that our device provided clinically relevant outcomes with a sufficient level of detail of the pulse wave and a high reliability (not less than 85%) in all clinically relevant situations. It was possible to record the effect of the Matas carotid occlusion test. COMPARISON WITH EXISTING METHOD(S): Our fully noninvasive, lightweight (185 g), portable, and wireless device provides a considerably cheaper alternative to the current diagnostic methods (e.g., transcranial ultrasound, X-ray, or MRI angiography) for specific assessment of cerebral circulation. Within a minute, it can detect the Willis circle integrity and thus eliminate the potential risks associated with the Matas test using standard EEG. CONCLUSIONS: Our device represents an improvement and a valid alternative to the current methods diagnosing regional cerebral circulation.

Reliability of ventilatory parameters during cycle ergometry in multicentre trials in COPD.

We studied the distribution profiles and repeatability of key exercise performance parameters in the first large multicentre trials to include these measurements in chronic obstructive pulmonary disease (COPD). After a screening visit, 463 subjects with COPD (mean+/-SD forced expiratory volume in 1 s 43+/-13% predicted) completed two run-in visits before treatment randomisation. At the run-in visits, measurements were conducted at rest, at a standardised time near end-exercise (isotime) and at peak exercise during constant work rate (CWR) cycle tests at 75% of each individual's maximum work capacity. The intraclass correlation coefficient was used to evaluate the test-retest repeatability of measurements of endurance time (ET), inspiratory capacity (IC), ventilation and dyspnoea intensity (Borg scale) during exercise. IC, ventilation and dyspnoea ratings were normally distributed; ET showed rightward skew (median or = 0.87). Ventilation was repeatable over the same time-points (R > or = 0.92), as was dyspnoea intensity at isotime (R = 0.79) and at peak exercise (R = 0.81). In conclusion, key perceptual and ventilatory parameters can be reliably measured during CWR cycle exercise in multicentre clinical trials in moderate to very severe COPD.

Absolute versus relative ascertainment of pedophilia in men.

There are at least two different criteria for assessing pedophilia in men: absolute ascertainment (their sexual interest in children is intense) and relative ascertainment (their sexual interest in children is greater than their interest in adults). The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, 3rd edition (DSM-III) used relative ascertainment in its diagnostic criteria for pedophilia; this was abandoned and replaced by absolute ascertainment in the DSM-III-R and all subsequent editions. The present study was conducted to demonstrate the continuing need for relative ascertainment, particularly in the laboratory assessment of pedophilia. A total of 402 heterosexual men were selected from a database of patients referred to a specialty clinic. These had undergone phallometric testing, a psychophysiological procedure in which their penile blood volume was monitored while they were presented with a standardized set of laboratory stimuli depicting male and female children, pubescents, and adults.The 130 men selected for the Teleiophilic Profile group responded substantially to prepubescent girls but even more to adult women; the 272 men selected for the Pedophilic Profile group responded weakly to prepubescent girls but even less to adult women. In terms of absolute magnitude, every patient in the Pedophilic Profile group had a lesser penile response to prepubescent girls than every patient in the Teleiophilic Profile group. Nevertheless, the Pedophilic Profile group had a significantly greater number of known sexual offenses against prepubescent girls, indicating that they contained a higher proportion of true pedophiles. These results dramatically demonstrate the utility-or perhaps necessity-of relative ascertainment in the laboratory assessment of erotic age-preference.