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Background During neonatal resuscitation, careful oxygenation is needed. Pulse oximetry is recommended to evaluate the need for oxygenation, but it is not clear whether peripheral perfusion is adequate for the evaluation of arterial oxygen saturation (SpO2). Additionally, there has been no study on the changes in SpO2 immediately after birth in Japan, despite the indispensable need for definitive oxygenation criteria. Methods A prospective observational study was performed in neonates at gestational age 35-41 weeks. An SpO2 measurement probe was attached to the neonates immediately after birth at the right palm or wrist, and the perfusion index ( PI), pulse rate, and SpO2 were measured until 10 min after birth. Results Sixty neonates were examined. Stable PI was obtained soon after birth, preceding SpO2 measurement. The median PI (%) was constant at approximately 1.3, and the median SpO2 at 2-10 min was 70%, 81%, 82%, 87%, 89%, 92%, 92%, 94%, and 95%, respectively. The current target value for SpO2 in the Neonatal Cardiopulmonary Resuscitation ( NCPR) guideline in Japan is approximately the 25th percentile. Conclusion PI is stable and sufficient in the early postnatal period, meaning that peripheral perfusion is adequate for the measurement of SpO2. The current target SpO2 used in the NCPR guidelines is at approximately the 25th percentile and is thought to be sufficient for meeting oxygenation criteria. [ABSTRACT FROM AUTHOR]

We sought to investigate whether carbohydrate-electrolyte beverage ingestion reduced heart rate (HR) in twenty-three healthy young adults while climbing Mount Fuji at a given exercise intensity. Twenty-three healthy adults were randomly divided into two groups: the tap water (11 males [M] and 1 female [F]) and the carbohydrate-electrolyte group (10 M and 1 F). HR and activity energy expenditure (AEE) were recorded every min. The HRs for the first 30 minutes of climbing were not significantly different between the groups [121 ± 2 beats per min (bpm) in the tap water and 116 ± 3 bpm in the carbohydrate-electrolyte]; however, HR significantly increased with climbing in the tap water group (129 ± 2 bpm) but showed no significant increase in the carbohydrate-electrolyte group (121 ± 3 bpm). In addition, body weight changes throughout two days ascending and descending on Mount Fuji were inversely related to changes in resting HR. Further, individual variation of body weight changes was suppressed by carbohydrate-electrolyte drink. Collectively, carbohydrate-electrolyte beverage intake may attenuate an increase in HR at a given AEE while mountaineering at ~3000 m compared with tap water intake. [ABSTRACT FROM AUTHOR]

Aim Although methicillin-resistant S taphylococcus aureus ( MRSA) is commonly isolated from respiratory specimens in healthcare-associated pneumonia ( HCAP), it is difficult to determine the causative pathogen because of the possibilities of contamination/colonization. The present study aimed to identify clinical predictors of the true pathogenicity of MRSA in HCAP. Methods Patients with HCAP with positive MRSA cultures in the sputum or endotracheal aspirates who were admitted to Seirei Mikatahara General Hospital, Hamamatsu, Japan, from 2009 to 2014 were enrolled. According to the administered drugs and the treatment outcomes, patients with true MRSA pneumonia ( MP) and those with contamination/colonization of MRSA (false MP) were identified. Baseline characteristics were compared between groups, and clinical predictors of true MP were evaluated by logistic regression analyses. Results A total of 93 patients (mean age 78.7 ± 12.6 years) were identified and classified into the true MP ( n = 16) or false MP ( n = 77) groups. Although baseline characteristics were broadly similar between groups, the true MP group had significantly more patients with PaO2 ≤ 60 Torr/pulse oximetry saturation ≤90% and those with MRSA single cultivation. Both variables were significant predictors of true MP in multivariate analysis (odds ratio of PaO2 ≤ 60 Torr/pulse oximetry saturation ≤90%: 5.64, 95% confidence interval 1.17-27.32; odds ratio of MRSA single cultivation: 4.76, 95% confidence interval 1.22-18.60). Conclusions Poor oxygenation and MRSA single cultivation imply the true pathogenicity of MRSA in HCAP with positive respiratory MRSA cultures. The present results might be helpful for the proper use of anti- MRSA drugs in this population. Geriatr Gerontol Int 2017; 17: 456-462. [ABSTRACT FROM AUTHOR]

Influence of different load exercise to muscle activity during subsequent exercise with 75% of one repetition maximum (RM) load among trained and untrained individuals was verified. Resistance-trained men who were involved in resistance training (n = 16) and healthy young men who did not exercise regularly (n = 16) were recruited for this study. Each subject performed bench pressing with a narrow grip exercise using two different training set methods, the drop-set (DS) (3 sets x 2-10 repetitions with 95-75% of 1RM) and the reverse drop-set (RDS) (3 sets x 3-10 repetitions with 55-75% of 1RM). The mean concentric contraction power, root mean square (RMS) of electromyogra-phy (EMG), area under the oxygenated hemoglobin (Oxy-Hb) curve, and time constant for muscle oxygen consumption (TcVO2mus) values of the triceps brachii were measured during and after the DS and RDS. The trained group demonstrated significantly higher mean muscle power (242.9 ± 39.6 W vs. 215.8 ± 31.7 W), RMS of EMG (86.4 ± 10.4 % vs. 68.3 ± 9.6 %), and area under the Oxy-Hb curve (38.6 ± 7.4 % • sec vs. 29.3 ± 5.8 % • sec) values during the DS than during the RDS (p < 0.05). However, in the untrained group none of the parameters differed significantly for both the DS and RDS. Furthermore, a negative correlation was detected between the area under the Oxy-Hb curve and muscle thickness (r = -0.51, p < 0.01). Long-term effects of DS on muscle strengthening and hypertrophy will be explored in further research. [ABSTRACT FROM AUTHOR]

Objective:The aim of this study was to identify the best sedation/analgesia protocol for laser photocoagulation (PC) of retinopathy of prematurity (ROP).Study Design:This multicenter observational study included five hospitals, each using a specific sedation/analgesia protocol: local anesthesia with oxybuprocaine hydrochloride (Group L); intravenous pentazocine (Group P); intravenous fentanyl (Group F); air, oxygen and sevoflurane (AOS) inhalation (Group I). The groups were compared for pain responses, vital signs and adverse events.Results:Heart rates and systemic blood pressures were elevated by PC in Groups L and P and Groups L, P and F, respectively. Moreover, poor analgesic efficacy was recognized in Groups L, P and F. In contrast, Group I experienced hypothermia, enteral feeding intolerance and apnea more frequently.Conclusion:From the viewpoint of sedation/pain relief, AOS anesthesia should be the best protocol. However, considering all the various factors together, the most reasonable one can be varied based on the patient's condition and hospital. [ABSTRACT FROM AUTHOR]

Previous studies demonstrated that treatment involving eccentric training was effective in the conservative management of chronic tendinosis. However, the mechanisms for these phenomena are unknown. The purpose of this study was to compare changes in blood circulation of the tendons after the repeated concentric and eccentric contractions. 11 healthy males volunteered for this study. Subjects performed the repeated concentric (CON) and eccentric (ECC) contractions (5 sets of 10 maximal voluntary contractions) of the plantar flexors. During and after repeated contractions, oxyhemoglobin (Oxy), deoxyhemoglobin (Deoxy), total hemoglobin (THb), and oxygen saturation (StO2) of the Achilles tendons were measured using red laser lights. Oxy and THb increased during and after ECC, but not CON. Deoxy decreased during both CON and ECC. Increase in StO2 during and after ECC was greater than that during and after CON. These results suggested that changes in blood circulation of the Achilles tendon during and after repeated eccentric contractions were more remarkable than those during and after repeated concentric contractions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Some patients with obstructive sleep apnea syndrome remove the CPAP device during sleep, although they start CPAP at bedtime. We hypothesized that body position changes and oxygen desaturations may be associated with patient removal of the CPAP device. METHODS: We consecutively enrolled 36 poor CPAP adherers and 25 good CPAP adherers. Body positions and oxygen desaturations were evaluated when these subjects used CPAP during sleep for 2 nights, permitting the removal of the CPAP device during the recording. RESULTS: Twelve poor CPAP adherers exhibited subject removal of the CPAP device within 4 h from the start of body position recording. The frequency of body position changes was significantly higher within 15 min before the CPAP removal than during other periods when CPAP was used. At the same time, oxygen desaturations were significantly more frequent within 15 min before CPAP removal than during other periods when CPAP was used. In addition, the majority (66.7%) of the CPAP removal events were followed by a change from a supine position to a non-supine position within 5 min. The number of body position changes during the first 4-h recording was significantly higher in the poor CPAP adherers who had removed their CPAP device compared with the poor CPAP adherers who had not removed their device. However, the number of body position changes or oxygen desaturation index under CPAP during the first 4-h recording was not significantly different between the poor CPAP adherers and good CPAP adherers. CONCLUSIONS: Our findings are the first to indicate associations among CPAP removal, body position changes, and oxygen desaturations during sleep in poor CPAP adherers. However, our findings also indicated that most good CPAP adherers make frequent body position changes without removal of CPAP device, suggesting that patients can adapt to the discomfort of CPAP therapy at the time of body position changes. [ABSTRACT FROM AUTHOR]

Background: Ankle exercise has been proven to be an effective intervention to increase venous velocity. However, the efficacy of ankle exercise for improving cerebral circulation has not been determined. We hypothesized that ankle exercise in the supine position would be able to increase oxyhemoglobin levels measured at the forehead. Methods: Seventeen community-dwelling elderly women participated in this study. We recorded blood pressure, heart rate (HR), and oxyhemoglobin (OxyHb) levels from the participants in the supine position. Participants repeated ankle plantar flexion and dorsiflexion movements for 1 min. Two types of exercise were used: active movement and passive movement. We used two-way analysis of variance to assess the differences in mean arterial blood pressure (MAP), HR, and OxyHb between different exercises (active and passive) and times (before and after exercise). Results: The HR and MAP increased during active exercise but not during passive exercise. On the other hand, the levels of OxyHb measured at the forehead were elevated during both active and passive exercises. This increase lasted at least 1 min after exercise. There was no significant difference between active and passive exercise with regard to OxyHb; however, a significant difference was observed between before and after exercise (p < 0.05, η²G = 0.153). Conclusions: The physiological response of OxyHb to ankle exercise was different from that of the other cardiovascular functions. Both active and passive ankle exercises were able to increase cerebral blood oxygenation, whereas the other cardiovascular functions did not respond to passive exercise. [ABSTRACT FROM AUTHOR]

Aim The aim of this study was to determine perinatal factors associated with cerebral palsy ( CP) in infants treated with brain hypothermia ( BHT). Material and Methods We carried out a retrospective review of 23 infants with hypoxic ischemic encephalopathy in whom BHT was applied within 6 h after birth. Outcome regarding the presence or absence of CP was assessed at the age of 18 months. Oxygen extraction fraction ( OEF) was measured before, during and after BHT at the jugular sinus. Results Three infants died and 12 developed CP (poor outcome group). The remaining eight infants did not have CP at 18 months old (favorable outcome group). There were no differences in gestational age, birthweight, pH, base deficit, or lactate level between infants with favorable and poor outcomes. Infants with flat trace on electroencephalography on admission were less likely to have favorable outcome (0.0% [0/8] vs 53% [8/15], respectively, P = 0.02), while those with Apgar score at 10 min ≥5 (57% [8/14] vs 0.0% [0/9], P = 0.007) or ≥6 (70% [7/10] vs 7.7% [1/13], P = 0.002), OEF ≥ 13.3% during BHT (64% [7/11] vs 8.3% [1/12], P = 0.009), and OEF ≥ 18.5% after BHT (73% [8/11] vs 0.0% [0/12], P = 0.002) were more likely to have favorable outcome compared with those with counterpart characteristics. Conclusion Infants with an Apgar score at 10 min ≥5, activity on electroencephalography on admission, and higher OEF during and after BHT were likely to have a favorable outcome. [ABSTRACT FROM AUTHOR]

Background Several reports have shown the beneficial effects of early or prophylactic surfactant therapy for preterm infants, who often develop respiratory distress syndrome. No report, however, has addressed which infants should receive surfactant therapy in the delivery room. Therefore, the aim of this study was to assess the validity of identifying infants who need surfactant therapy based on fraction of inspiratory oxygen ( FiO2) requirement in the delivery room. Methods In this observational, retrospective study, FiO2 given in the delivery room, use of surfactant therapy, stable microbubble test ( SMT) results, and changes in FiO2 both before and after surfactant therapy were reviewed in infants born at <33 weeks' gestation. Results Overall, 170 infants were included. Forty infants were given oxygen with FiO2 ≥0.6, and all received surfactant therapy. Of these 40 infants, FiO2 could be reduced in 36 (90%) by an average of 0.46 after surfactant therapy. SMT was done in 22 of 40 infants, and surfactant insufficiency was suspected in 20 (91%). In contrast, 81 of 102 infants (79%) with FiO2 <0.4 did not need surfactant therapy within 48 h after birth. Conclusions Preterm infants who need FiO2 ≥0.6 in the delivery room appear to be at high risk of surfactant insufficiency and would benefit from surfactant. Surfactant therapy would provide a more effective resuscitation method for preterm infants, and thus a larger prospective study is needed to confirm these results. [ABSTRACT FROM AUTHOR]

Monitoring the blood pump and the oxygen gas flow meter are important maneuvers at the initiation of cardiopulmonary bypass (CPB). We present a novel system, designed to improve safety in the heart-lung machine by linking the control of blood flow and the oxygen gas flow meter. This system uses a mass flow controller to provide and control oxygen flow based on the ventilation-perfusion (V/Q) ratio, using the electronic signal of the blood flow. We tested the system, in vitro and in vivo, and examined the resulting level of blood oxygenation. When extracorporeal circulation was initiated, the oxygen flow was instantly linked to the circulating blood flow, providing an adequate V/Q ratio; the partial pressure of oxygen in the blood was maintained at a normal level. Although we have yet to confirm the safety of this system in clinical trials, the new safety assist device can automatically supply oxygen to the oxygenator at the beginning of CPB. [ABSTRACT FROM PUBLISHER]

We compared the effect of recovery condition and durations on performance and muscle oxygenation during short-duration intermittent sprint exercise. 8 subjects performed a graded test and ten 5-s maximal sprints with 25-, 50-, and 100-s passive recovery (PR) or active recovery (AR) on a cycle ergometer. Peak power and percent decrease in power were determined. Oxygen uptake and blood lactate were measured during the sprint exercise. Oxyhemoglobin (O2Hb) and deoxyhemoglobin were measured using near-infrared spectroscopy. Peak power values were higher for PR than AR for the 25-s (2-9 sprints) and 50-s (2-6, 9, or 10 sprints) but not for the 100-s durations. Percentage decrease in peak power was lower for PR than AR in the 25-s (8.5 ± 2.5 vs. 11.5 ± 3.6 %, P = 0.008, ES = 0.66) and 50-s (2.7 ± 1.4 vs. 6.2 ± 3.5 %, P = 0.007, ES = 0.67) but not 100-s durations (2.1 ± 1.3 vs. 3.1 ± 2.6 %, P > 0.05). O2Hb variations were significantly higher for PR than AR for the 25-s and 50-s durations. AR was associated with reduced sprint performance and lower muscular reoxygenation. Performance was not affected over longer recovery durations regardless of recovery condition. [ABSTRACT FROM AUTHOR]

The article reports on research conducted to investigate the effect hyperbaric oxygen therapy had on blood circulation of human muscle and tendon in vivo. Researchers evaluated acute changes in blood volume and oxygen saturation of the medial gastrocnemius muscle and Achilles tendon during oxygen therapy. They found that changes in blood volume in the muscle increased after therapy but that oxygen saturation did not and that in the tendon both blood volume and oxygen saturation increased.

Background: Relatively little is known about acute exacerbation (AE) of interstitial pneumonia associated with collagen vascular diseases (CVD-IPs). Objectives: This study was aimed at clarifying clinical characteristics and outcome in AE of CVD-IPs, compared with those of idiopathic interstitial pneumonias (IIPs). Methods: We retrospectively reviewed 112 admission cases with suspected AE of CVD-IPs or IIPs during 2003-2009. IIPs were diagnosed with idiopathic pulmonary fibrosis (IPF) or non-IPF, mostly based on radiologic findings. Of these, 15 AEs of CVD-IPs (6 rheumatoid arthritis, 6 dermatomyositis and 3 systemic sclerosis) and 47 AEs of IIPs (13 IPF and 34 non-IPF) were included. Results: The clinical characteristics in AE of CVD-IPs were similar to those of IIPs, except for younger age (63.3 ± 6.8 vs. 73.8 ± 9.1 years; p = 0.0001) and higher PaO2/FiO2 at the onset of AE (205 ± 81.2 vs. 145 ± 53.8 mm Hg; p = 0.002) in the former. Dermatomyositis-related interstitial pneumonia (IP) showed a relatively indolent onset and was often associated with worsening control of the underlying disease, whereas AE of other CVD-IPs resembled that of IIPs. 90-day mortality of 33% in AE of CVD-IPs was similar to that of IIPs (44%; p = 0.44) or non-IPF (34%; p = 0.94), but was significantly better than that of IPF (69%; p = 0.04). Conclusion: Clinical features and outcome in AE of CVD-IPs were similar, if not identical, to those of IIPs, having a significant impact on the clinical course. AE of advanced IPF with typical radiologic features seems to have higher mortality compared with other forms of IP. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of acupuncture and heating (application of hot pack) treatments on blood circulation in the contralateral Achilles tendon. During the treatments (10 min for acupuncture, 20 min for heating) and recovery period (40 min), the blood volume (THb) and oxygen saturation (StO2) of the treated and the non-treated tendons were measured using red laser lights. During both treatments, THb and StO2 of the treated tendon increased significantly from the resting level. The increased THb and StO2 of the treated tendon were maintained until the end of the recovery period after removal of the acupuncture needle, although these values decreased after removal of the hot pack. Although THb of the non-treated sides did not change during both acupuncture and heating treatments, it increased gradually after removal of the acupuncture needle or the hot pack. For both treatments, the amount of increase in THb of the non-treated tendon was significantly correlated to that of the treated tendon during the last phase of recovery period. These results obtained from the healthy subjects imply that blood circulation in the injured tendon in a plaster cast may be improved by applying acupuncture or heating treatments to the contralateral healthy limb. [ABSTRACT FROM AUTHOR]

This open-label, nonrandomized study assessed single and repeat ascending doses of a new sublingual fentanyl (SLF) formulation in 48 healthy Japanese opiate-naïve subjects (47 completed). Subjects received single-dose SLF 100, 200, 400, or 800 µg followed by 13 doses 6 hourly, at their dose level. Subjects taking repeat-dose 400 and 800 µg were pretreated with naltrexone in order to block opiate-receptor–mediated effects on respiration, monitored by pulse oximetry and transcutaneous pco2. Sublingual fentanyl was rapidly and consistently absorbed. After single doses, median tfirst was 0.08 to 0.25 hours and tmax 0.50 to 1.00 hours. After repeat dosing, median tmax (tmax,ss) was 0.50 to 2.00 hours. Plasma concentrations were dose proportional both after single and repeat dosing, and naltrexone appeared to have no effect on SLF pharmacokinetics. Plasma fentanyl reached steady state within the 72-hour dosing period and accumulation was approximately 2-fold. After single doses, effects on respiratory variables were evident after the 400-µg and 800-µg doses. Transcutaneous pco2 was not helpful in detecting respiratory depression. Thus, SLF yielded rapid absorption of fentanyl and dose-proportional plasma concentrations that, for 400 µg and 800 µg, were within the typical analgesic range. Respiratory depression in these opioid-naïve volunteers was manageable with simple clinical measures. [ABSTRACT FROM PUBLISHER]

Background:Continuous positive airway pressure (CPAP) therapy has been shown to be effective in alleviating the underlying obstruction as well as reducing patients' excessive sleepiness and improving their functioning and health-related quality of life. However, residual excessive sleepiness is observed in some patients even though CPAP therapy eliminates sleep apnea and desaturation. Objectives:The aim of this study was to determine the prognostic effect of actigraphic sleep-wake rhythm evaluation in the management of patients with obstructive sleep apnea syndrome (OSAS) treated with CPAP. Methods: Eighteen patients with OSAS diagnosed by standard polysomnography (PSG; 48.1 ± 12.5 years) were enrolled in this study. The sleep-wake parameters were determined by actigraphy before and after 1 month of CPAP treatment, and results were compared with PSG data. In addition, data obtained before CPAP were compared with those measured after 1 month of CPAP treatment. Results:The total sleep time (TST) and sleep efficiency using PSG were significantly correlated with those using actigraphy. Bland-Altman plots of TST and sleep efficiency confirmed good agreement between PSG and actigraphy data. Sleep efficiency significantly improved following CPAP compared to baseline, and sleep fragmentation and sleep fragmentation >5 min determined by actigraphy were significantly lower during CPAP therapy than at baseline. Movement was significantly lower on CPAP therapy than at baseline. Conclusions:Actigraphy provides a valuable sleep-wake rhythm assessment in outpatients with OSAS where PSG is difficult to perform. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In order to establish an effective screening method for respiratory inhibition after crying (RIAC), we prospectively studied the correlations between infant RIAC and perinatal factors. We monitored infants ( n = 141) born from May through July 2009 with polygraphy and evaluated the presence of RIAC and respiratory pause that occurred when feeding was initiated immediately after crying with a decrease in oxygen saturation (SpO) to <60%. The infants were screened for increased echogenicity, a cyst in the ganglionic eminence (GE), or a subependymal cyst by cranial ultrasound. Furthermore, we evaluated the correlations between RIAC and perinatal factors. Eleven infants displayed RIAC and 31 experienced respiratory pause during feeding with a decrease in SpO to <60%. There were no significant correlations between RIAC and perinatal factors. Forty infants had ultrasound abnormalities (increased echogenicity in the GE, 26; cyst in the GE, nine; and subependymal cyst, seven). Sensitivity, specificity, and efficiency of abnormal cranial ultrasound findings for RIAC were 1.00, 0.777, and 0.794, respectively. The odds ratio, sensitivity, specificity, and efficiency of the combination of abnormal cranial ultrasound findings and respiratory pause during feeding with a decrease in SpO to <60% and RIAC were 35.9 ( P < 0.001), 0.727, 0.931, and 0.915, respectively. The combination of abnormal cranial ultrasound findings and respiratory pause during feeding with a decrease in SpO appears to be an effective method of screening for RIAC. [ABSTRACT FROM AUTHOR]

We compared the effects of Ringer's lactate (RL) and acetate (RA) solutions on parameters of splanchnic dysoxia such as PgCO2 (PCO2 of gastric mucosa) and pHi (pH of gastric mucosa) using a gastric tonometer, in addition to blood markers such as the serum arterial level of lactate, base excess, ketone body ratio, and antithrombin during the first 72h of the resuscitation period in patients with burns covering 30% or more of their body surface. A prospective study was conducted in the university tertiary referral centers. There were no significant differences in the average age, TBSA (total burn surface area), and resuscitative fluid volume during the first and second 24h between the two groups. In the RA group, PCO2 gap values calculated employing the formula: PgCO2 −PaCO2 (arterial PCO2), and pH gap calculated by: pHa (arterial pH)−pHi, improved to the normal ranges at 24h postburn, which was significantly faster than in the RL group. On the other hand, there were no significant differences in blood parameters between the two groups over the course. These results suggest that fluid resuscitation with RA may more rapidly ameliorate splanchnic dysoxia, as evidenced by gastric tonometry, compared to that with RL. [Copyright &y& Elsevier]

An abstract of the study "Optical Examination of the Efficacy of Contact Needle Therapy for Chemotherapy-Induced Peripheral Neuropathy: Integration of the Inspection of Kampo Therapy and the Color Spectrum Information" by Keiko Ogawa and colleagues is presented.

The present study evaluated whether slow-wave sleep and whole-night delta power of the non-rapid eye movement (NREM) sleep electroencephalogram (EEG) decrease during sleep at a simulated altitude of 2000 m, and whether such changes related to measures of hypoxic ventilatory response (HVR). This study consisted of two parts; in the first, HVR was measured in 41 subjects and each seven subjects with the lowest or the highest HVR were selected for the subsequent sleep study. In the second part, polysomnogram, arterial oxygen saturation (SpO2) and respiratory events are recorded on the selected subjects under normoxic and hypoxic conditions. Hypoxia decreased SpO2and increased respiratory disturbances for both groups. The low HVR group, but not the high HVR group, showed decreases in the whole-night delta power of NREM sleep EEG under hypoxia. On the other hand, two subjects in the high HVR group, who showed relatively high apnoea indices, also showed lower SpO2nadirs and decreases in the whole-night delta power under hypoxia. These results suggest that acute hypoxia equivalent to that at a 2000 m altitude decreases slow-wave sleep in individuals that show low HVR. However, low HVR may not be the only, but one of some factors that decrease the whole-night delta power under hypoxia. Therefore, it was not sufficient to identify individuals likely to be susceptible to deteriorated sleep quality at a simulated altitude of 2000 m only using the HVR test. Other factors, which relate to respiratory instabilities, should be taken into consideration to identify them. [ABSTRACT FROM AUTHOR]