Decrease In Arterial Oxygen Saturation Research Articles

Analysis of the factors of heart rate variability affected after a hypoxia tolerance test as a function of gender

Heart rate variability (HRV), the variation of time intervals between heartbeats, reflects the result of the interaction between the autonomic nervous system and the cardiovascular system. Hypoxia is a stressor that causes changes in HRV and a decrease in arterial oxygen saturation (SaO2). The aim of our study is to analyse if the time and frequency domains of HRV are affected after a hypoxia tolerance test in healthy participants as a function of gender. Material and methods: 23 healthy volunteers (11 women and 12 men) with a mean age of 23.08±2.99 performed a hypoxia tolerance test (11%, 5050 m) with the iAltitude simulator. Heart rate and SaO2 were monitored during the test and HRV frequency domain (FD) and time domain (TD) data were obtained. We analysed the five minutes before and after each session. Outcomes: Simulated altitude-induced hypoxia can cause changes in HRV in a group of healthy individuals. Statistically significant differences were also found between before and after the normobaric hypoxia test in the time-domain variables RRm, SDNN, HRm, HR STD, pNN50. In addition, in women statistically significant differences were found in RMSSD, and in the frequency-domain variables HF and LF/HF. While in males, statistically significant differences were found in SDNN. In both men and women, significant differences were observed in RRm, HRm and pNN50. Conclusion: The differences found in HRV after the hypoxia tolerance test indicate that females show a greater activation of the parasympathetic nervous system compared to males. While males showed greater sympathetic activation. Keywords: Heart rate variability, normobaric hypoxia, stress, autonomic nervous system.

Prospective clinical validation of the Empatica EmbracePlus wristband as a reflective pulse oximeter.

Respiratory diseases such as chronic obstructive pulmonary disease, obstructive sleep apnea syndrome, and COVID-19 may cause a decrease in arterial oxygen saturation (SaO2). The continuous monitoring of oxygen levels may be beneficial for the early detection of hypoxemia and timely intervention. Wearable non-invasive pulse oximetry devices measuring peripheral oxygen saturation (SpO2) have been garnering increasing popularity. However, there is still a strong need for extended and robust clinical validation of such devices, especially to address topical concerns about disparities in performances across racial groups. This prospective clinical validation aimed to assess the accuracy of the reflective pulse oximeter function of the EmbracePlus wristband during a controlled hypoxia study in accordance with the ISO 80601-2-61:2017 standard and the Food & Drug Administration (FDA) guidance. Healthy adult participants were recruited in a controlled desaturation protocol to reproduce mild, moderate, and severe hypoxic conditions with SaO2 ranging from 100% to 70% (ClinicalTrials.gov registration #NCT04964609). The SpO2 level was estimated with an EmbracePlus device placed on the participant's wrist and the reference SaO2 was obtained from blood samples analyzed with a multiwavelength co-oximeter. The controlled hypoxia study yielded 373 conclusive measurements on 15 subjects, including 30% of participants with dark skin pigmentation (V-VI on the Fitzpatrick scale). The accuracy root mean square (Arms) error was found to be 2.4%, within the 3.5% limit recommended by the FDA. A strong positive correlation between the wristband SpO2 and the reference SaO2 was observed (r = 0.96, P < 0.001), and a good concordance was found with Bland-Altman analysis (bias, 0.05%; standard deviation, 1.66; lower limit, -4.7%; and upper limit, 4.8%). Moreover, acceptable accuracy was observed when stratifying data points by skin pigmentation (Arms 2.2% in Fitzpatrick V-VI, 2.5% in Fitzpatrick I-IV), and sex (Arms 1.9% in females, and 2.9% in males). This study demonstrates that the EmbracePlus wristband could be used to assess SpO2 with clinically acceptable accuracy under no-motion and high perfusion conditions for individuals of different ethnicities across the claimed range. This study paves the way for further accuracy evaluations on unhealthy subjects and during prolonged use in ambulatory settings.

Unraveling the Underlying Molecular Mechanism of 'Silent Hypoxia' in COVID-19 Patients Suggests a Central Role for Angiotensin II Modulation of the AT1R-Hypoxia-Inducible Factor Signaling Pathway.

A few days after being infected with SARS-CoV-2, a fraction of people remain asymptomatic but suffer from a decrease in arterial oxygen saturation in the absence of apparent dyspnea. In light of our clinical investigation on the modulation of molecules belonging to the renin angiotensin system (RAS) in COVID-19 patients, we propose a model that explains 'silent hypoxia'. The RAS imbalance caused by SARS-CoV-2 results in an accumulation of angiotensin 2 (Ang II), which activates the angiotensin 2 type 1 receptor (AT1R) and triggers a harmful cascade of intracellular signals leading to the nuclear translocation of the hypoxia-inducible factor (HIF)-1α. HIF-1α transactivates many genes including the angiotensin-converting enzyme 1 (ACE1), while at the same time, ACE2 is downregulated. A growing number of cells is maintained in a hypoxic condition that is self-sustained by the presence of the virus and the ACE1/ACE2 ratio imbalance. This is associated with a progressive worsening of the patient's biological parameters including decreased oxygen saturation, without further clinical manifestations. When too many cells activate the Ang II-AT1R-HIF-1α axis, there is a 'hypoxic spillover', which marks the tipping point between 'silent' and symptomatic hypoxia in the patient. Immediate ventilation is required to prevent the 'hypoxic spillover'.

Hypoxic White Matter Injury and Recovery After Reoxygenation in Adult Mice: Magnetic Resonance Imaging Findings and Histological Studies.

Cognitive dysfunction and brain white matter (WM) injury have been found in adults exposed to hypoxia. However, the mechanisms underlying these impairments remain unclear, and moreover, it is also unclear whether these impairments are reversible after reoxygenation. In this study, adult male mice were exposed to hypoxia for 15days at a simulated altitude of 4300m and then reoxygenated for 2months. Control mice were raised under normoxic conditions. Mice showed a significant decrease inarterial oxygen saturation (SaO2)and an increase in heart rate and breath rate after hypoxic exposure, and they displayed anxiety-like emotion and impaired cognitions. Hypoxic mice showed decreased brain WM fractional anisotropy(FA) and increased mean diffusion (MD) mainly in the corpus callosum and internal capsule. The reason for the adult brain WM injury was myelin rather than axon. Further, the myelin injury was due to the obstruction of oligodendrocyte precursor cells (OPCs) differentiation and eventually led to behavioral deficits. More importantly, the changes in physiological indicators, behavioral disorders, and WM injury caused by hypoxia can be recovered after reoxygenation. Taken together, our data indicate that adult brain WM injury caused by hypoxia is reversible after reoxygenation and enhancing OPCs differentiation may be a promising therapy for clinical hypoxic diseases associated with brain injury. Schematic diagram of brain WM and behavioral changes induced by hypoxia/reoxygenation in adult mice.

The physiological, perceptual, and thermoregulatory responses to facemask use during exercise.

The use of masks in public settings and when around people has been recommended to limit the spread of Coronavirus disease 2019 (COVID-19) by major public health agencies. Several different types of masks classified as either medical- or non-medical grade are commonly used among the public. However, concerns with difficulty breathing, re-breathing exhaled carbon dioxide, a decrease in arterial oxygen saturation, and a decrease in exercise performance have been raised regarding the use of mask during exercise. We review the current knowledge related to the effect of different masks during exercise on cardiorespiratory, metabolic, thermoregulatory, and perceptual responses. As such, the current literature seems to suggest that there are minimal changes to cardiovascular, metabolic, and no changes to thermoregulatory parameters with facemask use. However, differences in ventilatory parameters have been reported with submaximal and maximal intensity exercise to volitional fatigue. Literature on perceptual responses to exercise indicate an impact on ratings of perceived exertion, dyspnea, and overall discomfort dependent on mask use as well as exercise intensity. In conclusion, data from the current literature suggests a minimal impact on physiological, perceptual, and thermoregulatory responses dependent on the type of mask used during exercise.

Congenital heart disease and air travel.

The number of individuals traveling by airplanes is increasing every year. Patients with congenital heart disease and shunts, exposure to high altitude during a flight is important since it causes pulmonary vaso- constriction leading to an increase in right-to-left shunting and a decrease in arterial oxygen saturation. Patients with cyanotic congenital heart disease and Eisenmenger syndrome should be evaluated before the flight, and necessary precautions should be taken.

Comparison the Sedation Effect and Satisfaction of Two Combinations, Dexmedetomidine and Fentanyl with Midazolam and Fentanyl, in Patients Undergoing Bronchoscopy

Objectives: The aim of this study was to compare sedative effects of dexmedetomidine and fentanyl with midazolam and fentanyl in patients undergoing bronchoscopy.&#x0D; Methods: This study was a double-blind randomized clinical trial that was performed on 92 patients who referred to Amir al Momenin Hospital in Arak for bronchoscopy and underwent ASA 1 or 2 underlying grading procedure. Patients were randomly divided into two groups of dexmedetomidine and fentanyl (D) midazolam and fentanyl (M). Primary vital signs including hypertension and arterial oxygen saturation were monitored and recorded. Then all patients were injected with 2 μg / kg fentanyl as a painkiller and after 3 minutes 30 μg dexmedetomidine in syringe with code A and midazolam 3 mg in syringe with code B were injected to patients by an anesthesiologist. Then the two groups were compared in terms of pain at injection, conscious relaxation, satisfaction of operation, recovery time, hypotension and arterial oxygen saturation and drug side effects and data were analyzed by using statistical tests.&#x0D; Results: There was no significant difference between the two groups in terms of mean age and sex distribution. According to the results of this study, there was no significant difference between the two groups in mean blood pressure (P-value = 0.6) and mean heart rate (P-value = 0.4) at the time of bronchoscopy, but at 5 and 10 minutes after bronchoscopy there was a significant difference, mean blood pressure and heart rate were significantly lower in dexmedetomidine group.&#x0D; Conclusion: Both dexmedetomidine and midazolam drug groups contributed to the development of stable and sedative hemodynamics and satisfaction in patients undergoing bronchoscopy, however, the dexmedetomidine and fentanyl group showed a significant decrease in blood pressure and heart rate compared to midazolam and fentanyl and a weaker decrease in arterial oxygen saturation, and patients with bronchoscopy were more satisfied in the dexmedetomidine group.

A Focused Review on the Maximal Exercise Responses in Hypo- and Normobaric Hypoxia: Divergent Oxygen Uptake and Ventilation Responses.

The literature suggests that acute hypobaric (HH) and normobaric (NH) hypoxia exposure elicits different physiological responses. Only limited information is available on whether maximal cardiorespiratory exercise test outcomes, performed on either the treadmill or the cycle ergometer, are affected differently by NH and HH. A focused literature review was performed to identify relevant studies reporting cardiorespiratory responses in well-trained male athletes (individuals with a maximal oxygen uptake, VO2max > 50 mL/min/kg at sea level) to cycling or treadmill running in simulated acute HH or NH. Twenty-one studies were selected. The exercise tests in these studies were performed in HH (n = 90) or NH (n = 151) conditions, on a bicycle ergometer (n = 178) or on a treadmill (n = 63). Altitudes (simulated and terrestrial) varied between 2182 and 5400 m. Analyses (based on weighted group means) revealed that the decline in VO2max per 1000 m gain in altitude was more pronounced in acute NH vs. HH (−7.0 ± 1.4% vs. −5.6 ± 0.9%). Maximal minute ventilation (VEmax) increased in acute HH but decreased in NH with increasing simulated altitude (+1.9 ± 0.9% vs. −1.4 ± 1.8% per 1000 m gain in altitude). Treadmill running in HH caused larger decreases in arterial oxygen saturation and heart rate than ergometer cycling in acute HH, which was not the case in NH. These results indicate distinct differences between maximal cardiorespiratory responses to cycling and treadmill running in acute NH or HH. Such differences should be considered when interpreting exercise test results and/or monitoring athletic training.

The Frequency of Monocyte Chemoattractant Protein-1 Gene Polymorphism in Obstructive Sleep Apnea Syndrome.

In obstructive sleep apnea syndrome (OSAS) many proinflammatory cytokines are released from activated endothelial cells due to repeated decreases in arterial oxygen saturation. Some of these proinflammatory cytokines are involved in the etiology of coronary artery disease (CAD). Although the association between OSAS and CAD is known, risk factors for CAD have not been determined in this patient group. Monocyte chemoattractant protein-1 (MCP-1) is a proinflammatory cytokine that plays a key role in the development of atherosclerosis. In this study, we compared the frequency of MCP1 rs1024610-rs1024611 single-nucleotide polymorphisms (SNPs) in OSAS patients with no comorbidity, OSAS patients with no comorbidity except CAD, and healthy individuals. The study included 301 subjects. Two hundred one patients with OSAS (OSAS only and OSAS + CAD groups) and 100 healthy control subjects underwent polysomnography. MCP1 rs1024610 and rs1024611 mutation frequencies were determined. Body mass index, apnea-hypopnea index, triglyceride levels, and mean oxygen desaturation were significantly higher in the OSAS patients than in the healthy population (p < 0.05). In MCP1 rs1024611 SNP analysis, homozygous mutation was significantly more common in the OSAS + CAD group than in the OSAS and control groups (p < 0.001). MCP1 rs1024610 SNP analysis showed no significant differences among the study groups. OSAS patients with homozygous MCP1 rs1024611 SNP are at higher risk for CAD. The MCP1 rs1024610 SNP was not associated with incidence of CAD. Patients with OSAS and MCP1 rs1024611 homozygous mutation are more susceptible to CAD and early detection and treatment may significantly reduce mortality and morbidity.

The Results of Surgical Treatment of Hypertension in Mild and Moderate Obstructive Sleep Apnea Syndrome

Background: Obstructive sleep apnea syndrome (OSAS) is the most common respiratory disorder related to sleep. It is characterized by recurrent upper airway obstruction episodes and a decrease in arterial oxygen saturation during sleep. The most important complications of OSAS are related to the cardiovascular system. Hypertension (30% - 60%) is the leading cause of these complications. Objectives: This study aimed to investigate the removal of upper airway obstruction through surgical operations in the tension treatment of OSAS patients with hypertension. Methods: This retrospective study included 42 patients with hypertension from 2008 to 2017 who were diagnosed with OSAS based on the result of polysomnogram (PSG) test. All the patients were examined in detail in otorhinolaryngology and cardiology clinics, their endoscopic and imaging evaluations were carried out and their blood pressure was followed-up. Preoperative and postoperative arterial blood pressure values for upper airway obstruction were statistically analyzed. Results: The mean preoperative systolic and diastolic arterial blood pressure values of the patients with hypertension were 152.3 ± 21.2 and 97.2 ± 12.3 mmHg, respectively. Their postoperative systolic and diastolic arterial blood pressure levels were found to be 124.5 ± 19.3 and 86.4 ± 12.1 mmHg, respectively (P < 0.05). This decrease in the arterial blood pressure was significant. Conclusions: Removal of upper airway obstruction through a surgical operation was found to play an important role in the blood pressure treatment of OSAS patients with hypertension.

Efficiency of Expansion Sphincter Pharyngoplasty in the Treatment of Obstructive Sleep Apnea Syndrome.

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper respiratory-tract obstruction during sleep and decrease in arterial oxygen saturation. Expansion sphincter pharyngoplasty (ESP) is a simple, safe, and effective method for the surgical treatment of OSAS. The aim of our study was to evaluate the efficacy of ESP with polysomnography (PSG) in OSAS patients. This study was conducted on patients referred to our center for the treatment of snoring, apnea, witnessed apnea, and daytime sleepiness during 2010-2018. Overall, 67 patients (16 females, 51 males) who had PSG test at postoperative three months and were considered suitable with history, physical examination, and surgery after PSG were included in the study. Patients were classified into three groups according to OSAS severity: mild, moderate, and severe. Patient age, sex, body mass index (BMI), pre- and postoperative period apnea-hypopnea index (AHI), Epworth sleepiness scores, and PSG data were recorded. The mean BMI of all groups was 27.44±2.73. The postoperative AHI decreased from 18.26±2.23 to 8.01±0.97 (p<0.001). Surgical success rate was 67.2%; it was higher in females (p=0.047). The highest success rate was found in the mild OSAS group; however, this difference was not statistically significant when compared to the other groups (p=0.217). There were statistically significant improvement at postoperative Epworth sleepiness scores and minimum O2 saturations (p<0.001 and p=0.018, respectively). ESP is an effective and successful surgery in selected patients with lateral pharyngeal and retropalatal narrowing.

Acute lung injury induced by intestinal ischemia and reperfusion is altered in obese female mice

RationalAcute lung injury (ALI) is a common complication after intestinal ischemia and reperfusion (I/R) injury that can lead to acute respiratory distress syndrome (ARDS). We have previously demonstrated that females are protected against lung damage induced by intestinal I/R through an estrogen mediated mechanism. ObjectivesTo investigate the effect of obesity on ALI induced by intestinal I/R in female mice. MethodsC57Bl/6 female mice were fed with a standard low-fat diet (SD) or a high-fat diet (HFD) for 9 weeks. Intestinal I/R injury was induced by a 45 min occlusion of the mesenteric artery followed by 2 and 24 h of reperfusion. ResultsSignificant increase in lung myeloperoxidase expression (MPO) and neutrophil numbers of SD and HFD mice occurred at 2 h and 24 h of reperfusion. Furthermore, HFD mice presented a significant increase in lung eosinophil peroxidase (EPO) expression and eosinophil numbers compared to SD mice. Lung wet/dry weight ratio was significantly greater in HFD mice at 2 and 24 h of reperfusion, accompanied by a significant increase in the expression of inducible NO in the lung tissue and a significant decrease in arterial oxygen saturation at 24 h of reperfusion relative to SD mice. ConclusionObesity predisposes female mice to increased pulmonary oedema and deterioration in gas exchange, which is accompanied by an increase in iNOS expression in the lung.

Hemoconcentration During Maximum Exercise in Miners with Chronic Intermittent Exposure to Hypobaric Hypoxia (3800 m)

To evaluate the effect of maximum exercise on hemoconcentration in miners with chronic intermittent hypobaric hypoxia (CIHH) at 3800 m. Sixteen miners with CIHH at high altitude (3800 m) were subjected to maximum exercise levels on a cycle ergometer, increasing exercise load by 50 W every 3 minutes at sea level and high altitude (3800 m). During exercise, arterial oxygen saturation and heart rate were measured. Blood samples were taken at each step to measure hemoglobin concentration and hematocrit. Arterial blood oxygen content was also calculated. At sea level, a decrease in arterial oxygen saturation to 92.1% ± 2.5% was observed at 150 W and the hematocrit, hemoglobin concentration and oxygen content were not altered. At high altitude, arterial oxygen saturation decreased, reaching 88.2% ± 4.9% at 50 W and remained constant during the entire exercise protocol. Hemoglobin concentration and hematocrit increased reaching 16.4 ± 0.9 g/dL and 48.8% ± 1.6%, respectively, at 100 W and were maintained until recovery. Arterial oxygen content was constant during exercise and increased in the recovery period. An increase in hemoglobin concentration during exercise compensates for the decline in arterial oxygen saturation, meanwhile arterial oxygen content remains constant.

Physiological Dynamic Apnea Responses in Relation to Apnea Capacity in Triathletes.

The aim was to assess the cardiac, arterial oxygen saturation, lactate, hormonal and Borg rating of perceived exertion (RPE) responses to acute apnea in relation to apnea capacity in 18 middle-aged triathletes. Subjects were monitored while swimming two 50-m freestyle exercise trials with fins at maximal speed: with normal frequency breathing (NB) and with complete apnea (Ap); the latter was used to assess apnea capacity. The subjects with significant alteration in swimming performance inducing a time increase greater than 2.5% during Ap vs. NB were put in the group: bad apnea capacity (Bad Ap); the others, who showed no significant alteration in performance, were put in the group: Good Ap. Under apnea, both groups showed a decrease in arterial oxygen saturation (p<0.05). In Ap conditions, only Bad Ap had a significant lower maximal heart rate vs. NB (p<0.05), with lower blood lactate (p<0.05) and arm stroke frequency (p<0.01). No change in saliva hormonal concentrations was found during the experiment for both groups, whereas RPE responses were increased in the Good Ap group under Ap vs. NB conditions. In conclusion, a good apnea capacity seems to be associated with lower cardiovascular and metabolic apnea alterations in middle-aged recreationally-trained triathletes.

Diurnal changes of arterial oxygen saturation and erythropoietin concentration in male and female highlanders.

In Caucasians and Native Americans living at altitude, hemoglobin mass is increased in spite of erythropoietin concentrations ([Epo]) not markedly differing from sea level values. We hypothesized that a nocturnal decrease of arterial oxygen saturation (SaO2) causes a temporary rise of [Epo] not detected by morning measurements. SaO2 (continuous, finger oximeter) and [Epo] (ELISA, every 4 h) were determined in young highlanders (altitude 2600 m) during 24 h of usual daily activity. In Series I (six male, nine female students), SaO2 fell during the night with the nadir occurring between 01:00 and 03:00; daily means (range 92.4–95.2%) were higher in females (+1.7%, P < 0.01). [Epo] showed opposite changes with zenith occurring at 04:00 without a sex difference. Mean daily values (22.9 ± 10.7SD U/L) were higher than values obtained at 08:00 (17.2 ± 9.5 U/L, P < 0.05). In Series II (seven females), only SaO2 was measured. During follicular and luteal phases, SaO2 variation was similar to Series I, but the rhythm was disturbed during menstruation. While daily [Epo] variations at sea level are not homogeneous, there is a diurnal variation at altitude following changes in SaO2. Larger hypoventilation‐dependent decreases of alveolar PO2 decreases during the night probably cause a stronger reduction of SaO2 in highlanders compared to lowlanders. This variation might be enlarged by a diurnal fluctuation of Hb concentration. In spite of a lower [Hb], the higher SaO2 in women compared to men led to a similar arterial oxygen content, likely explaining the absence of differences in [Epo] between sexes.

4650m 상당의 평압·저산소 조건에서 근지구성 운동이 심박변이도에 미치는 영향

The purpose of this study was to investigate the effect of extreme normobaric hypoxia exposure corresponding to 4650m altitude on heart rate variability during muscular endurance exercise. In a cross-over design, 19 young (21.7±2.4years) healthy males were asked to perform the isokinetic leg endurance exercise twice in hypoxia and control(sea level) condition with a week interval. Subjects assigned to the hypoxia condition group was breathed in hypoxia air corresponding to 4,650m altitude condition for 30minutes through the hypoxic control device(Altrainer, SMTEC Sports & Medical Technologies SA, Nyon, Switzerland). Each Subject conducted iso-kinetic knee flexion and extension exercise at 180°/sec, 10bouts, and 10sets using isokinetic dynamometer(Biodex system 4, Medical System Inc, USA). The parameters of heart rate variability were obtained from both time-and frequency domain analysis of 5min EC G recording at rest, post exercise, and post 10min(3 time) after exercise. Mean RR interval and its standard deviation(SDNN), the mean square successive differences(RMSSD), the low and high frequency components were calculated as normalized units. Arterial oxygen saturation was also measured by pulse oximetry at rest, post exercise, and post 10minute. The results were as follows. First, following the hypoxia exposure a significant decrease in arterial oxygen saturation was found(p.05). Second, analysis of HRV revealed a significant increase in sympathetic activity and a significant decrease in parasympathetic activity following muscular endurance exercise both group(p0.1~0.05). Third, no significantly different in parameters of HRV was not found between the hypoxia group and the control group. These findings suggest that the dropped level of arterial oxygen saturation induced by hypoxia exposure may not affect heart rate variability at resting status, during exercise and recovery period. The results also showed that exercise itself rather than status of blood might have more powerful effect on autonomic nerve activities.

Effect Of Training Under Hyperoxia On Exercise Performance And Aerobic Capacity In Trained Cyclists

Some previous studies suggested that trained athletes can perform exercise at high power outputs and long duration during inspiration of a hyperoxic gas mixture, which would inhibit the decrease in arterial oxygen saturation (SpO2) levels during intense exercise. Training under hyperoxia could increase aerobic capacity, and thus improve exercise performance in trained athletes. PURPOSE: This study aimed to determine the effect of training under hyperoxia on exercise performance and aerobic capacity in trained cyclists. METHODS: Six male trained cyclists (age: 21.3 ± 1.9 yr, height: 168.6 ± 5.5 cm, weight: 59.7 ± 9.0 kg) performed training under hyperoxia. Before the training periods (pre-training), the subjects performed an incremental exercise test to exhaustion in which the work rate at initiation was 120 W for 3 min. The work rate was then increased as a step function by 40 W every 3 min at a pedal rate of 90 rpm to determine the workload corresponding to the maximal oxygen uptake (VO2max) and work rate max (WRmax) by using a bicycle ergometer. VO2max was determined by calculating the average of the breath–by–breath data over 30-s intervals during the incremental test. All the subjects underwent training under hyperoxia on 3 days per week for a 4-weeks period. The training protocol consisted of 5 repetitions of intense exercise at 3–min intervals. The intensity of the intense exercise was 90–100% WRmax. The duration of the intense exercise was 3 min in sets of 1–4, and the subjects cycled to voluntary exhaustion in 5 sets. All the subjects completed the training under conditions of hyperoxic gas mixture (36.1–37.2% O2). They also performed the incremental exercise test 3–6 days after the training periods (post-training). RESULTS: The time required by the subjects to perform the incremental exercise test in the post-training period was significantly longer than that required in the pre-training period (16.69 ± 1.64 min vs. 15.81 ± 2.22 min; p = 0.022). There were no statistically significant differences in VO2max between the post-training period and the pre-training period (57.2 ± 6.0 ml min-1 vs. 56.2 ± 6.6 ml min-1). CONCLUSION: Our results showed that submaximal training with inspiration of a hyperoxic gas mixture for 4 weeks improves exercise performance in trained cyclists.

Duration criterion of respiratory events for children with obstructive sleep apnea

ObjectiveTo investigate the duration criterion of respiratory events in children with obstructive sleep apnea syndrome (OSAS) by analyzing standard nocturnal polysomnograms (PSG). To provide reference values for pediatric PSG. Methods107 OSAS children diagnosed by PSG from January 2004 to May 2006 were randomly selected. The decrease in arterial oxygen saturation (ΔSaO2) and the corresponding event duration of each respiratory event were observed. Results(1) There was significant positive correlation between oxygen desaturation values (ΔSaO2=0–17%) and the corresponding durations of respiratory events (P<0.001). (2) There was no significant difference in durations of respiratory events in rapid eye movement (REM) sleep and NREM sleep, the demographics between male and female children. (3) Significant positive correlation between age and duration of respiratory events (apnea/hypopnea) when oxygen desaturation values equal to 4% (ΔSaO2=4%) was observed. (4) The lower limit of 95% confidence intervals of which duration of oxygen desaturation value equals to 4% was 5.4s. Conclusion(1) PSG studies may allow the establishment of the duration criterion of significant respiratory events; (2) 5.4s can be defined as duration criteria of respiratory events; (3) the present study provides reference values for Pediatric PSG.

Comparative Analysis of Lateral Pharyngoplasty and Uvulopalatopharyngoplasty Techniques With Polisomnography and Epworth Sleepiness Scales

Snoring is caused by the vibration of structures of the oral cavity, such as the soft palate, uvula, tonsils, base of the tongue, epiglottis, and lateral pharyngeal walls. When these structures collapse and obstruct the airway, apnea occurs. Obstructive sleep apnea syndrome (OSAS) is characterized by repeated periods of upper airway obstruction, a decrease in arterial oxygen saturation, and interrupted sleep. The prevalence of OSAS is 1% to 5% in men and 1.2% to 2.5% in women. Crucial factors in deciding the surgical approach include a detailed ear-nose-throat examination, Muller maneuver, sleep endoscopy, and apnea hypopnea index scores. Accepted treatments include continuous positive airway pressure (CPAP), surgeries of the base of the tongue and/or palate, and multi-level surgeries. It, however, is important to continue to evaluate the efficacies of such procedures. The authors evaluated the outcomes of 23 patients who underwent surgery for OSAS, using preoperative and postoperative polysomnography (PSG) and the Epworth sleepiness scale (ESS). The results were compared before and after surgery. In all, 14 patients had lateral pharyngoplasty and 9 had uvulopalatopharyngoplasty (UPPP). The PSG and Epworth scale values were significantly lower in both groups, postoperatively. Patients indicated that their quality of life had improved. In conclusion, the surgeries were successful. In line with the literature, our results indicate that lateral pharyngoplasty and UPPP can be used in appropriate patients. Longer-term studies on more patients will provide more detailed information in the future.

General Anesthesia for Lumbar Puncture and Bone Marrow Aspiration /Biopsy in Children

Background Multiple procedures (Lumbar puncture and bone marrow aspiration /biopsy) cause pain, stress, depression and etc for the patients and their families. Various methods have been recommended for pain reduction during invasive procedures. The aim of this study is to report the complications following general anesthesia. Methods In this prospective observational study, two hundred and two children with cancer were enrolled. All patients received propofol 2.5 mg /kg and fentanyl 1 µg/kg. After adequate anesthesia, procedures were performed by a pediatric oncologist. All anesthesia complications were classified into two groups: Intraoperative and Postoperative complications. Complications which were recorded include: abnormal age-specific bradycardia (≤20 × baseline), decrease in arterial oxygen saturation (≤90%), laryngospasm, vomiting, agitation, headache, hypothermia ( 37/8 C°), signs of allergy, traumatic LP (bloody), and unusual local bleeding. Results In this study, 118 males and 84 females underwent 623 general anesthetic procedures with a median of 3 procedures per patient. Intraoperative period complications occurred in 48 of total 623 procedures (7.7 %). The most common complications were traumatic LP, bradycardia and decrease in arterial oxygen saturation which occurred in 25, 6 and 6 cases, respectively. Postoperative period complications occurred in 74 (11.9%) cases. The most common complications were vomiting, agitation and headache, decrease O2 saturation and bradycardia. Conclusion General anesthesia by propofol and fentanyl may be a good choice for short-term painful procedures in children undergoing treatment for bone marrow aspiration/biopsy and intratechal injection. Key Words: Embryonic stem cells; Bone Marrow, Biopsy.