Endotypic traits of supine position and supine-predominant obstructive sleep apnoea in Asian patients.

BACKGROUND: Over half of all cases of obstructive sleep apnoea (OSA) are classified as supine-related OSA; however, the pathological endotype during supine position is not fully understood. This study aims to investigate the endotypic traits of supine-predominant OSA and explore the variations in endotypic traits between the supine and lateral positions. METHODS: We prospectively recruited 689 adult patients with OSA from a single sleep centre between April 2020 and December 2022. Endotypic traits, namely arousal threshold, collapsibility, loop gain and upper airway muscle compensation, were retrieved from polysomnographic signals. We identified spOSA by a supine to non-supine apnoea-hypopnoea index (AHI) ratio >2. We cross-sectionally compared demographic and endotypic traits between supine-predominant OSA and non-positional OSA and examined the associations between supine-predominant OSA and endotypic traits. Additionally, we compared the changes in endotypic traits between supine and lateral positions in patients with supine-predominant OSA and non-positional OSA. RESULTS: In our study sample, 75.8% of patients were identified as having supine-predominant OSA. Compared to non-positional OSA, supine-predominant OSA was associated with low collapsibility (ß= -3.46 %eupnoea, 95% CI -5.93- -1.00 %eupnoea) and reduced compensation (ß= -6.79 %eupnoea, 95% CI -10.60- -2.99 %eupnoea). When transitioning from the lateral to supine position, patients with supine-predominant OSA had a substantial decrease in compensation compared to those with non-positional OSA (-11.98 versus -6.28 %eupnoea). CONCLUSIONS: Supine-predominant OSA is the prevalent phenotype of OSA in Asian patients. Inadequate upper airway compensation appears to be a crucial underlying pathology in patients with supine-predominant OSA.

Force Production Measurements During a Supine Medicine Ball Throw: a Reliability and Correlation Study.

OBJECTIVES: This study aimed to examine the reliability of supine medicine ball throw peak force and rate of force development (RFD) measurements. A secondary aim was to investigate the correlations between these measurements and vertical jump height. METHODS: Twenty young women (21±3 years) reported for experimental testing on two different occasions. Supine medicine ball throw assessments were performed during each testing session to assess peak force, RFDmax, and RFD at specific percentages of peak force (RFD30% and RFD40-80%). Vertical jumps were performed on a jump mat. The jump mat measured vertical jump height based on flight time. RESULTS: Good intraclass correlation coefficients (≥0.82) and coefficients of variation (≤14.0%) were observed between sessions for peak force, RFDmax, and RFD40-80%, but not for RFD30% (0.55, 27.2%). There were significant correlations between jump height and peak force (r=0.483, P=0.031), RFDmax (r=0.484, P=0.031), and RFD40-80% (r=0.491, P=0.028). There was no significant correlation between jump height and RFD30% (r=0.359, P=0.120). CONCLUSIONS: Our results showed that supine medicine ball throw peak force, RFDmax, and RFD40-80% were reliable measures for assessing upper-body explosive strength in young adults. These measurements were significantly associated with vertical jump height and therefore, may be effective predictors of one's athletic ability.

Effect of lateral position on rostral fluid shift and relationship to severity of Cheyne-Stokes respiration in heart failure patients.

PURPOSE: Lateral sleep position has a significant beneficial effect on the severity of Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) in patients with heart failure (HF). We hypothesized that a reduction in rostral fluid shift from the legs in this position compared with the supine position may contribute to this effect. METHODS: In patients with CSR-CSA and an apnea-hypopnea index (AHI) ≥ 15/h (by standard polysomnography), uncalibrated leg fluid volume was measured in the supine, left lateral decubitus, and right lateral decubitus positions (in-laboratory assessment). The correlation between postural changes in fluid volume and corresponding changes in AHI was evaluated. Since there was no difference in both leg fluid volume and AHI between the right and left positions, measurements in these two conditions were combined into a single lateral position. RESULTS: In 18 patients with CSR-CSA, leg fluid volume increased by 2.7 ± 3.1% (p = 0.002) in the lateral position compared to the supine position, while AHI decreased by 46 ± 20% (p < 0.0001) with the same postural change. The correlation between postural changes in AHI and leg fluid volume was 0.22 (p = 0.42). Changes in leg fluid volume were a slow phenomenon, whereas changes in CSR-CSA severity were almost synchronous with changes in posture. CONCLUSION: Lateral position causes a reduction in rostral fluid shift compared to the supine position, but this change does not correlate with the corresponding change in CSR-CSA severity. The two changes occur on different time scales. These findings question the role of postural changes in rostral fluid shift as a determinant of corresponding changes in CSR-CSA severity.

Higher awakening threshold of preterm infants in prone position may be a risk factor for SIDS.

AIM: The supine sleeping position in the prevention of sudden infant death syndrome in preterm infants is poorly understood. We aimed to investigate the effect of sleep posture on cardiorespiratory parameters and movement patterns in preterm infants close to discharge. METHODS: This observational study included neonates born in 2022 at the University Hospital Schleswig-Holstein, Lübeck, Germany. Motion sensor data, heart rate, respiratory rate and oxygen saturation were recorded for infants with postconceptional age 35-37 weeks during sleep in the prone and supine positions. RESULTS: We recorded data from 50 infants, born at 31 (24-35) weeks of gestation (mean(range)), aged 5.2 ± 3.7 weeks (mean ± SD), of whom 48% were female. Five typical movement patterns were identified. In the prone position, the percentage of calm, regular breathing was higher and active movement was less frequent when compared to the supine position. The percentage of calm irregular breathing, number of apnoeas, bradycardias, desaturations and vital sign changes were not influenced by position. CONCLUSION: The prone position seems to be associated with a higher arousal threshold. The supine position appears advantageous for escape from life-threatening situations such as sudden infant death syndrome.

ISSLS prize in clinical/bioengineering science 2024: How standing and supine positions influence nutrient transport in human lumbar discs?-A serial post-contrast MRI study evaluating interplay between convection and diffusion.

PURPOSE: The intervertebral disc being avascular depends on diffusion and load-based convection for essential nutrient supply and waste removal. There are no reliable methods to simultaneously investigate them in humans under natural loads. For the first time, present study aims to investigate this by strategically employing positional MRI and post-contrast studies in three physiological positions: supine, standing and post-standing recovery. METHODS: A total of 100 healthy intervertebral discs from 20 volunteers were subjected to a serial post-contrast MR study after injecting 0.3 mmol/kg gadodiamide and T1-weighted MR images were obtained at 0, 2, 6, 12 and 24 h. At each time interval, images were obtained in three positions, i.e. supine, standing and post-standing recovery supine. The signal intensity values at endplate zone and nucleus pulposus were measured. Enhancement percentages were calculated and analysed comparing three positions. RESULTS: During unloaded supine position, there was slow gradual increase in enhancement reaching peak at 6 h. When the subjects assumed standing position, there was immediate loss of enhancement at nucleus pulposus which resulted in reciprocal increase in enhancement at endplate zone (washout phenomenon). Interestingly, when subjects assumed the post-standing recovery position, the nucleus pulposus regained the enhancement and endplate zone showed reciprocal loss (pumping-in phenomenon). CONCLUSIONS: For the first time, present study documented acute effects of physiological loading and unloading on nutrition of human discs in vivo. While during rest, solutes diffused gradually into disc, the diurnal short loading and unloading redistribute small solutes by convection. Standing caused rapid solute depletion but promptly regained by assuming resting supine position.

The effect of sleep position on sleep bruxism in adults with obstructive sleep apnea.

BACKGROUND: Most of the respiratory events in adults with obstructive sleep apnea (OSA) occurs in supine position. It has been reported that the contraction of masseter muscles is dependent on the occurrence of arousals rather than on the occurrence of respiratory events. OBJECTIVES: This study had two aims: (1) to compare the rhythmic masticatory muscle activity (RMMA) index in supine position (RMMA_sup) and in non-supine positions (RMMA_nsup) in adults with OSA; and (2) to determine the associations between RMMA index in both supine position and non-supine positions on the one hand, and several demographic and polysomnographic variables on the other hand. METHODS: One hundred OSA participants (36 females and 64 males; mean age = 50.3 years (SD = 10.5)) were selected randomly from among patients with a full-night polysomnographic recording. RMMA_sup index and RMMA_nsup index were compared using Mann-Whitney U-test. Multivariate linear regression analyses were used to predict RMMA index both in supine and non-supine positions based on several demographic and polysomnographic variables. RESULTS: In patients with OSA, the RMMA_sup index was significantly higher than the RMMA_nsup index (p < .001). RMMA_sup index was significantly associated with the arousal index (p = .002) and arousal index in supine position (p < .001). RMMA_nsup index was only significantly associated with the arousal index in non-supine positions (p = .004). CONCLUSION: Within the limitations of this study, RMMAs occur more frequently in supine position than in non-supine positions in patients with OSA. In both sleep positions, RMMAs are associated with arousals.

Orthostatic variation of pulmonary artery pressure in ambulatory heart failure patients.

AIM: To study effect of change in position (supine and standing) on pulmonary artery pressure (PAP) in ambulatory heart failure (HF) patients. METHODS: Seventeen patients with CardioMEMS® sensor and stable heart failure were consented and included in this single center study. Supine and standing measurements were obtained with at least 5 min interval between the two positions. These measurements included PAP readings utilizing the manufacturer handheld interrogator obtaining 10 s data in addition to the systemic blood pressure and heart rate recordings. RESULTS: Mean supine and standing readings and their difference (Δ) were as follows respectively: Systolic PAP were 33.4 (± 11.19), 23.6 (± 10) and Δ was 9.9 mmHg (p = 0.0001), diastolic PAP were 14.2 (± 5.6), 7.9 (± 5.7) and Δ was 6.3 mmHg (p = 0.0001) and mean PAP were 21.8 (± 7.8), 14 (± 7.2) and Δ was 7.4 mmHg (p = 0.0001) while the systemic blood pressure did not vary significantly. CONCLUSION: There is orthostatic variation of PAP in ambulatory HF patients demonstrating a mean decline with standing in diastolic PAP by 6.3 mmHg, systolic PAP by 9.9 mmHg and mean PAP by 7.4 mmHg in absence of significant orthostatic variation in systemic blood pressure or heart rate. These findings have significant clinical implications and inform that PAP in each patient should always be measured in the same position. Since initial readings at the time of implant were taken in supine position, it may be best to use supine position or to obtain a baseline standing PAP reading if standing PAP is planned on being used.

Why upright standing men urinate more efficiently than in supine position: A morphological analysis with real-time magnetic resonance imaging.

PURPOSE: Few studies have examined the effects of body position on urination efficiency morphologically. We aimed to dissect out the anatomical changes of pelvic organs during urination in the upright and supine positions by a real-time magnetic resonance imaging (rtMRI) system. METHODS: Thirteen healthy male volunteers aged 26-60 years were included in the study. The sagittal real-time two-dimensional images were taken to evaluate urinary efficiency, along with change in six morphological indices at the time of storage and the beginning of voiding, in both upright ant supine positions. RESULTS: Urination was more efficient in upright position than in supine position, as expressed by higher average rate of bladder emptying (9.9 ± 4.2 vs. 6.8 ± 2.9 ml/s, p < 0.05) and also by fewer participants showing significant residual urine (1/13 vs. 7/13, p < 0.05). At the onset of voiding in standing position, the levator ani (LA) muscle moves downward and backward followed by descent of the bladder neck and rotation of the prostate around the symphysis. Such changes were expressed by two morphological indices. One was posterior vesicourethral angle at the start of voiding, 152 ± 7 versus 140 ± 1 in upright and supine position (p < 0.05). The other index was the change in angle between the LA line and pubo-coccygeal line in upright and supine position, 9.4 ± 9.9 versus 1.6 ± 7.9 before voiding (p < 0.05) and 30.2 ± 14.0 versus 17.3 ± 12.9 after the start of voiding (p < 0.05). CONCLUSION: The dynamic relaxation of LA seemed to be a key movement that enables more efficient urination in standing position than in supine position.

Intraoperative pressure monitoring of the lower leg for preventing compression-related complications associated with the lithotomy position.

BACKGROUND: Several serious complications are associated with the lithotomy position, including well-leg compartment syndrome and peroneal nerve paralysis. The aims of this study were to identify risk factors for the intraoperative elevation of lower leg pressure and to evaluate the effectiveness of monitoring external pressure during surgery for preventing these complications. METHODS: The study included 106 patients with a diagnosis of sigmoid colon or rectal cancer who underwent elective laparoscopic surgery between June 2019 and December 2020. We divided the posterior side of the lower leg into four parts (upper outside, upper inside, lower outside, lower inside) and recorded the peak pressure applied to each area at hourly intervals during surgery (called "regular points") and when the operating position was changed (e.g., by head-tilt or leg elevation; called "points after change in position"). When the pressure was observed to be higher than 50 mmHg, we adjusted the position of the leg and re-recorded the data. Data on postoperative leg-associated complications were also collected. RESULTS: The pressure was measured at a total of 1125 points (regular, n = 620; after change of position, n = 505). The external pressure on the upper outer side of the right leg (median, 36 mmHg) was higher than that on any other area of the lower leg. The pressure increase to more than 50 mmHg was observed not only during the change of position (27.5%) but also during regular points (22.4%). Bodyweight, strong leg elevation, and low head position were identified as factors associated with increased external pressure. There have been no compression-related complications in 534 cases at our institution since the introduction of intraoperative pressure monitoring. CONCLUSIONS: Several risk factors associated with increased external pressure on the lower leg were identified. Intraoperative pressure monitoring might help reduction of pressure-related complications, needing further and larger prospective data collections.

Anesthesiology trainees performing flexible scope intubation in spontaneously breathing patients in the left lateral position and the supine position: a prospective randomized trial.

BACKGROUND: Flexible scope intubation is an important airway management skill that requires hands-on training in a real airway. We compared flexible scope intubation by trainees between patients in the left lateral and supine positions. METHODS: Forty patients aged 20 to 80 years with American Society of Anesthesiologists physical status class I to III were scheduled for elective surgery under general endotracheal anesthesia in Ramathibodi Hospital from February 2020 to June 2020. Patients were randomly assigned to be intubated in one of two positions: supine (Group S) or left lateral (Group L). Trainees performed flexible scope intubation in sedated patients under the supervision of an attending anesthesiologist. Intubation success, time to successful intubation, number of attempts, airway adjustment maneuvers, and hemodynamic changes were compared between groups. RESULTS: Patient characteristics did not differ between groups except for Mallampati airway classification. The rate of successful intubation on the first attempt and intubation time did not significantly differ between groups. The proportion of patients who required a jaw thrust during intubation was significantly lower in Group L (10.5% vs. 85%; P < 0.01). Blood pressure and oxygen saturation declined in both groups after intubation. The relative risk of desaturation in patients in the left lateral position compared with the supine position was 0.44 (0.1649-1.1978). CONCLUSION: The rate of successful flexible scope intubation on the first attempt and intubation time did not differ between the groups. The proportion of patients who required a jaw thrust maneuver was significantly lower in patients in the left lateral position. TRIAL REGISTRATION: https://www.thaiclinicaltrials.org/ ( TCTR20200208001 ) on 08/02/2020.

The outcome of oral appliance therapy on position-dependent obstructive sleep apnea: A multicenter randomized controlled trial.

INTRODUCTION: This multicenter trial on patients with obstructive sleep apnea (OSA) treated with an oral appliance aimed to determine the effect of sleeping positions. METHODS: A cohort of 314 patients with OSA were enrolled and evaluated at 8 weeks and 1 year, focusing on treatment effects. At baseline and the 2 follow-ups, new polygraphic registration comparing the proportion of treatment responders without position-dependent OSA (non-position-dependent OSA [non-POSA]) and with POSA was used. RESULTS: At the 8-week and 1-year follow-up, 205 and 139 patients were included, respectively. The proportion of responders (apnea-hypopnea index [AHI] <10 and/or ≥50% reduction in AHI) was 56% for the non-POSA group and 69% for the POSA group (not significant [NS]). The responders increased at the 1-year follow-up: 68% and 77% for the non-POSA and POSA groups (NS), respectively. The absolute change in AHI in all sleeping positions at 8 weeks was -12.9 (interquartile range, -25.0 to -0.5) in the non-POSA group and -10.5 (interquartile range, -19.9 to -5.3; NS) in the POSA group. However, the decrease in supine AHI was significantly greater among subjects with POSA. In contrast, the decrease in nonsupine AHI was significantly greater in the non-POSA group, an effect that remained at the 1-year follow-up. CONCLUSIONS: Our hypothesis that subjects with POSA at baseline would have a higher treatment response rate after oral appliance treatment compared with subjects without POSA was rejected. However, those with POSA had a significantly higher supine AHI decrease, and those without POSA had significantly less nonsupine AHI.

Cerebral Oxygenation and Perfusion when Positioning Preterm Infants: Clinical Implications.

OBJECTIVES: To evaluate cerebral tissue oxygenation (cTOI) and cerebral perfusion in preterm infants in supine vs prone positions. STUDY DESIGN: Sixty preterm infants, born before 32 weeks of gestation, were enrolled; 30 had bronchopulmonary dysplasia (BPD, defined as the need for respiratory support and/or supplemental oxygen at 36 weeks of postmenstrual age). Cerebral perfusion, cTOI, and polysomnography were measured in both the supine and prone position with the initial position being randomized. Infants with a major intraventricular hemorrhage or major congenital abnormality were excluded. RESULTS: Cerebral perfusion was unaffected by position or BPD status. In the BPD group, the mean cTOI was higher in the prone position compared with the supine position by a difference of 3.27% (P = .03; 95% CI 6.28-0.25) with no difference seen in the no-BPD group. For the BPD group, the burden of cerebral hypoxemia (cumulative time spent with cTOI <55%) was significantly lower in the prone position (23%) compared with the supine position (29%) (P < .001). In those without BPD, position had no effect on cTOI. CONCLUSIONS: In preterm infants with BPD, the prone position improved cerebral oxygenation and reduced cerebral hypoxemia. These findings may have implications for positioning practices. Further research will establish the impact of position on short- and long-term developmental outcomes.

Blood flow response to orthostatic challenge identifies signatures of the failure of static cerebral autoregulation in patients with cerebrovascular disease.

BACKGROUND: The cortical microvascular cerebral blood flow response (CBF) to different changes in head-of-bed (HOB) position has been shown to be altered in acute ischemic stroke (AIS) by diffuse correlation spectroscopy (DCS) technique. However, the relationship between these relative ΔCBF changes and associated systemic blood pressure changes has not been studied, even though blood pressure is a major driver of cerebral blood flow. METHODS: Transcranial DCS data from four studies measuring bilateral frontal microvascular cerebral blood flow in healthy controls (n = 15), patients with asymptomatic severe internal carotid artery stenosis (ICA, n = 27), and patients with acute ischemic stroke (AIS, n = 72) were aggregated. DCS-measured CBF was measured in response to a short head-of-bed (HOB) position manipulation protocol (supine/elevated/supine, 5 min at each position). In a sub-group (AIS, n = 26; ICA, n = 14; control, n = 15), mean arterial pressure (MAP) was measured dynamically during the protocol. RESULTS: After elevated positioning, DCS CBF returned to baseline supine values in controls (p = 0.890) but not in patients with AIS (9.6% [6.0,13.3], mean 95% CI, p < 0.001) or ICA stenosis (8.6% [3.1,14.0], p = 0.003)). MAP in AIS patients did not return to baseline values (2.6 mmHg [0.5, 4.7], p = 0.018), but in ICA stenosis patients and controls did. Instead ipsilesional but not contralesional CBF was correlated with MAP (AIS 6.0%/mmHg [- 2.4,14.3], p = 0.038; ICA stenosis 11.0%/mmHg [2.4,19.5], p < 0.001). CONCLUSIONS: The observed associations between ipsilateral CBF and MAP suggest that short HOB position changes may elicit deficits in cerebral autoregulation in cerebrovascular disorders. Additional research is required to further characterize this phenomenon.

The effectiveness of the laid-back position on lactation-related nipple problems and comfort: a meta-analysis.

BACKGROUND: The importance of breastfeeding for maternal and child health is agreed upon worldwide. However, lactation-related nipple problems are common and are important factors affecting breastfeeding. Multiple studies recommended laid-back breastfeeding, but they are of various levels of quality, and the results are inconclusive. METHODS: We systematically searched the following twelve databases from inception to January 28,2020: Cochrane Library, EMBASE, Medline, Ovid, PubMed, Web of Science, CINAHL, Scopus, Chinese National Knowledge Infrastructure (CNKI), China Biology Medicine disc (CBM), WanFang, and VIP. All studies regarding laid-back breastfeeding or biological nurturing were considered, regardless of whether they were randomized controlled trials. Two trained investigators independently evaluated the quality of the selected articles and screened the data. All the data were analysed separately using Review Manager Version 5.3 and STATA/SE Version 15.1. RESULTS: A total of 12 studies involving 1936 groups of postpartum women and their newborns were included. The results of the meta-analysis showed that nipple pain (RR = 0.24; 95% CI 0.14, 0.40; p < 0.00001), nipple trauma (RR = 0.47; 95% CI 0.29, 0.75; p = 0.002) and correct latching position (RR = 1.22; 95% CI 1.11, 1.33; p < 0.0001) in the experimental groups were all better than those of the control groups, and the differences were statistically significant (p < 0.05), which indicates that the laid-back position has a positive effect on maternal breastfeeding. However, the results of position comfort showed that there was no statistical significance between the two groups (ES = 0.09; 95% CI -0.63, 0.81; p = 0.798). CONCLUSION: Compared with traditional breastfeeding positions, the laid-back position has been proven to be related to a decreased incidence of nipple pain and nipple trauma and is seemingly conducive to the use of the correct latching position. It is suggested that the laid-back position is helpful in solving lactation-related nipple problems and can be recommended as a position for breastfeeding. However, no significant difference in position comfort was found between the two groups based on the current evidence, and further studies are still needed to validate these results due to the limitations of the included studies.

The effects of whole-body vibration on EMG activity of the lower body muscles in supine static bridge position.

OBJECTIVES: The purpose of the current study was to firstly examine the effects of different whole-body vibration (WBV) frequencies in the lower-body muscles when applied simultaneously during a bridge exercise. Secondly, determine if there were any sex differences in the lower-body muscles of WBV during the bridge. METHODS: Seven females and 7 males completed 2 familiarization and 1 test sessions. In the test session participants were randomized to complete one 30 s bout of a bridge exercise for 3 separate conditions followed by 3-min of rest. The 3 conditions (a) No-WBV (without WBV); (b) WBV-30 (30 Hz, low amplitude); (c) WBV-50 (50 Hz, low amplitude) were performed on a WBV platform. Muscle activity of the biceps femoris (BF), semitendinosus (ST), gluteus maximus (Gmax), multifidus muscle (MF) muscles were measured. RESULTS: Muscle activity was increased with WBV in the BF and ST muscles at WBV-30 and WBV-50 conditions (p<0.05) vs. no-WBV. During No-WBV and WBV-50 conditions, males had a higher biceps femoris activity compared to females for (p<0.05) 45 and 27 %, respectively; however, during all conditions females had a high level of Gmax activity (57%) than males (p<0.05). CONCLUSION: Additional vibration at 30 and 50 Hz during the bridge exercise could be a useful method to enhance hamstring muscle activity.

Muscle length influence on rectus femoris damage and protective effect in knee extensor eccentric exercise.

This study tested the hypothesis that the magnitude of rectus femoris (RF) damage and the repeated bout effect (RBE) would be greater after knee extensor eccentric exercise performed in a supine (long RF lengths) than a sitting (short RF lengths) position, and the muscle length effects would be more prominent at the proximal than distal RF. Young untrained men were placed to one of the two groups (n = 14 per group). S group performed the knee extensor eccentric exercise in the sitting position for the first bout and the supine position for the second bout, and L group performed the exercise in the supine position for two bouts, with 4 weeks between bouts. Dependent variables included evoked and maximal voluntary isometric contraction (MVC) torque, electromyography (EMG) during MVC, muscle soreness, and shear modulus, which were measured before and 1-3 days after each exercise bout. After the first bout, L group in comparison with S group showed greater (P < .05) changes in hip flexor MVC torque (average of 1-3 days post-exercise: -11.1 ± 9.4% vs -5.0 ± 7.5%), proximal RF EMG (-22.4 ± 16% vs -9.0 ± 21.9%), and proximal RF shear modulus (33.2 ± 22.8% vs 16.9 ± 13.5%). No significant differences between groups were evident for any of other variables after the first bout including knee extensor MVC torque, and for the changes in all variables after the second bout. These results supported the hypothesis that RF damage would be greater for the spine than sitting position especially at the proximal region, but did not support the hypothesis about the RBE.

Effects of wrist position on eccentric exercise-induced muscle damage of the elbow flexors.

We tested the hypothesis that the magnitude of changes in indirect muscle damage markers would be greater after maximal elbow flexor eccentric exercise in the supinated (shorter biceps brachii) than neutral wrist (longer) position, and the difference in the magnitude would be associated with greater elongation over contractions for the supinated than neutral position, rather than the initial muscle length. Ten untrained men (21-39 years) performed two bouts of 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors in the supinated position for one arm and neutral position for the other arm separated by 2 weeks in a randomized order. Biceps brachii myotendinous junction (MTJ) movements during eccentric contractions were recorded by B-mode ultrasonography, and the displacement from the start to end of each contraction was quantified. Peak torque (supinated: 367.8 ± 112.5 Nm, neutral: 381.5 ± 120.4 Nm) and total work (1816 ± 539 J, 1865 ± 673 J) produced during eccentric contractions were similar between conditions. The average MTJ displacement increased (P < .05) from the 1st set (8.0 ± 2.0 mm) to 10th set (15.8 ± 1.9 mm) for the supinated condition, but no such increase was found in the neutral condition (1st set: 5.1 ± 1.0 mm, 10th set: 5.0 ± 0.8 mm). Changes in indirect muscle damage markers (maximal voluntary isometric contraction torque, range of motion, serum creatine kinase activity, and muscle soreness) after exercise were greater (P < .05) for the supinated than neutral condition. These results suggest that the greater muscle damage marker changes for the supinated than neutral wrist position was associated with the greater muscle lengthening (strain).

Combination of positional therapy with positive airway pressure for titration in patients with difficult to treat obstructive sleep apnea.

INTRODUCTION: Positional therapy has been described as add-on therapy to a mandibular advancement device, but the efficacy of combination of positional therapy and positive airway pressure (PPAP) has not been documented. We have found PPAP therapy as an effective method of titration in patients with difficult to treat OSA (obstructive sleep apnea). METHODOLOGY: This retrospective analysis was done in patients who had difficult to treat OSA, i.e., in whom titration in the supine position was unacceptable with any PAP device (CPAP or bilevel PAP) and could only be successfully titrated with a PAP device in the lateral position. This study describes our experience of PPAP therapy. Baseline characteristics and polysomnography data of patients who were successfully titrated in supine v/s lateral positions were compared. RESULTS: Of 272 consecutive patients with OSA selected for analysis, 218 patients (191 and 27 with CPAP and bilevel PAP, respectively) could be successfully titrated in supine position. Further 54 (20%) patients in whom titration in supine position was unacceptable were titrated in lateral position. Patients titrated with PAP in the lateral position therapy group had higher BMI, higher neck and waist circumference, and lower awake sPO2 and nadir sPO2 during sleep, and spent more time in sleep with sPO2 < 90%. CONCLUSION: Combination of positional therapy and PAP device is an effective way of titration for difficult to treat OSA patients. It can be tried in patients who fail titration in supine position.

The effect of in-lab polysomnography and home sleep polygraphy on sleep position.

PURPOSE: Little is known regarding the influence of in-laboratory polysomnography (PSG) equipment on sleep position, especially on the prevalence of supine positioning, which in many cases may lead to a more severe sleep apnea diagnosis. The aim of this study was to assess the percentage of supine sleep during an in-laboratory PSG compared to that seen during a home sleep apnea test (HSAT). METHODS: This was a retrospective cohort study comparing in-laboratory PSG and HSAT using a peripheral arterial tone (PAT) technology device. RESULTS: Of 445 PSG and 416 HSAT studies analyzed, there was no significant difference in the proportion of supine sleep time between PSG (44%) and HSAT (45%, p = 0.53). Analysis of the differences in sleep position (supine versus non-supine), analyzed by sex, BMI (≥ 30 kg/m2 versus < 30 kg/m2), and age (≥ 60 years versus < 60 years), was significant only for women, who had more supine sleep during HSAT at 61 ± 24% than during PSG at 45 ± 26% (p < 0.001). CONCLUSION: Overall there was no difference in the percentage of supine sleep when comparing in-laboratory PSG to HSAT. However, women had more supine sleep with HSAT than with PSG.

Truth or Myth: Intra-abdominal Pressure Increases in the Lithotomy Position.

STUDY OBJECTIVE: To determine if there were differences in intra-abdominal pressure (IAP) in the supine, low lithotomy, and high lithotomy positions. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: Twenty-nine women undergoing surgery for prolapse or stress incontinence. INTERVENTIONS: Relevant medical history, including the pelvic organ prolapse quantification stage, body mass index, and airway grade (Mallampati score), was abstracted from patients' medical charts. IAP was measured in centimeters of water (cmH2O) on the day of their surgery before induction of general or intravenous anesthesia using a T-doc air charged urodynamic catheter (Laborie Aquarius; Ontario, Canada) placed in a patient's vagina (for patients with incontinence) or rectum (for patients with prolapse). MEASUREMENTS AND MAIN RESULTS: IAP was measured in 3 positions: supine (legs at 0°), low lithotomy (legs in Yellowfin stirrups at 45°; Allen Medical, Acton, MA), and high lithotomy (legs at 90°). The means ± SDs IAP for the groups were as follows: in the supine position, 18.6 cmH2O ± 7.6; low lithotomy, 17.7 cmH2O ± 6.6; and high lithotomy, 17.1 cmH2O ± 6.3. In the same women, there was a significant decrease in IAP from the supine to high lithotomy positions, with a mean difference of 1.4 cmH2O ± 3.7, p = .05. Similarly, there was a significant, though smaller, decrease in mean IAP when moving from the supine to low lithotomy positions in these same women (mean decrease of 0.9 cmH2O ± 1.5, p = .004). Neither change is clinically significant based on previous research that suggests 5 cmH2O is a clinically significant change. CONCLUSION: Placing patients' legs in a low or high lithotomy position does not result in a clinically significant increase in IAP. Therefore, surgeons and anesthesiologists can consider positioning patients' lower extremities in stirrups while patients are awake to minimize discomfort and possibly reduce the risk of nerve injuries.