Changes In SpO2 Research Articles

Atrial septal defects versus ventricular septal defects in BREATHE-5, a placebo-controlled study of pulmonary arterial hypertension related to Eisenmenger's syndrome: A subgroup analysis

Eisenmenger's syndrome (ES) is the most advanced form of pulmonary arterial hypertension related to congenital heart disease. Evolution of pulmonary vascular disease differs markedly between patients with atrial septal defects (ASD) versus ventricular septal defects (VSD), potentially affecting response to treatment. We compared the effects of bosentan and placebo in patients with isolated ASD (ASD subgroup) versus patients with isolated VSD or both defects (VSD subgroup). Post-hoc analysis of a 16-week, multicenter, randomized, double-blind, placebo-controlled trial was performed. Fifty-four patients (13: ASDs, 36: VSDs, 5: VSD+ASD) were randomized to bosentan 62.5 mg bid for four weeks (uptitrated to 125 mg bid thereafter) or placebo. Main outcome measures were: indexed pulmonary vascular resistance (PVRi), exercise capacity, mean pulmonary artery pressure (mPAP), pulmonary blood flow index (Qpi), and changes in oxygen saturation (SpO₂). Placebo-corrected median (95% CI) treatment effects on PVRi were -544.0 dyn·s·cm⁻⁵ (-1593.8, 344.7) and -436.4 dyn·s·cm⁻⁵ (-960.0, 167.0) in the ASD and VSD subgroups, respectively. Effects of bosentan on exercise capacity and mPAP were similar in both subgroups. No changes in SpO₂ or Qpi were observed in either bosentan or placebo subgroups. Improvements in exercise capacity and cardiopulmonary hemodynamics, without desaturation, were observed in ES patients with both ASDs and VSDs. Although not reaching statistical significance, improvements were similar to those in the BREATHE-5 analyses, suggesting that the location of septal defects is not a key determinant of treatment response. These data further support the use of bosentan for the treatment of ES, independent of shunt location.

Pulse oximetric thresholds for tonsillectomy and adenotomy in children: significance of 1–2% decline in oxyhemoglobin saturation

We aimed to establish optimal overnight pulse oximetric thresholds for determining the indication of tonsillectomy and adenotomy (TA) in children by revising the definition of 'desaturation'. One hundred and thirty four children scheduled for TA (TA group, 5.3 +/- 1.4 years old) and 112 otherwise healthy children scheduled for elective minor surgery (control group, 5.4 +/- 1.5 years old) were enrolled into this prospective study. Data were recorded and stored every 10 s using Nellcor N-395. Desaturation/resaturation events were defined as x% change (x = 1-4) of SpO2 (oxyhemoglobin saturation by pulse oximetry) in 10 s. The desaturation/resaturation indices were calculated as events per hour of total sleeping time. For each index, a wide range of temporary thresholds was set. The optimal thresholds for TA were the ones that maximized the weighted average for sensitivity, specificity (based on whether the index improved or not after TA), and the percentage of the control children whose indices were below the threshold. For all the indices, the optimal thresholds that fulfilled the above condition were determined. Compared with the x = 3-4% results, the application of x = 1-2% approximately doubled the TA patients whose preoperative 'positive' indices improved after TA, with the weighted averages of 84.3-92.3% as described above. By defining desaturation/resaturation as a 1-2% change in SpO2 from the preceding value, children with adenotonsillar hypertrophy whose pulse oximetric indices are expected to improve after TA can be detected by pulse oximetry with relatively high sensitivity and specificity.

Effects of Monster Energy drink on cardiovascular and renal function

Recent anecdotal reports have linked energy drink consumption with adverse cardiovascular side effects, especially among college‐aged persons. Drinks, such as Monster Energy (ME), contain a wide variety of ingredients, including but not limited to caffeine, whose physiological effects are not completely understood. This study sought to determine if ME was associated with physiologically significant changes. Following an overnight fast, human subjects (age 19.39±1.03 years; 52 female; 23 male) were randomized to ME (2 servings; 480ml; 200 Cal), Isocaloric sugar water (480 ml; 200 Calories), low Cal sugar water (480 ml; 100 Calories), Water (480 ml; 0 calories), or nothing. Heart rate (HR), hematocrit (Hct%), SpO2, blood glucose, urine specific gravity (USG), urine volume (UV), and urine formation rate (UFR) were measured before beverage administration (0‐minutes), then 30‐, 60‐, and 120‐min postprandially. Visual reaction times (VRT) were measured at 0‐ and 60 min. No significant changes in HR, Hct%, SpO2, UV, and UFR were observed within or between groups. Blood glucose did increase significantly for subjects receiving 200 and 100 calorie treatments. USG decreased significantly in all subjects receiving any beverage. VRT improved significantly following ME consumption. This study suggests that ME consumption improves reaction time and was not associated with any adverse effects.

When should oxygen be given to children at high altitude? A systematic review to define altitude-specific hypoxaemia

Background:Acute respiratory infections (ARI) cause 3 million deaths in children worldwide each year. Most of these deaths occur from pneumonia in developing countries, and hypoxaemia is the most common fatal...

Perioperative nursing for patients with meningiomas of tentorial incisures

Objective To summarize the perioperative experience of nursing for patients with meningiomas of tentorial ineisures (MTI). Methods Nursing data of clinical therapy of 22 microsurgery resection patients with MTI were summarized retrospectively. Results The morbidity and mortality of early postoperative complications of MTI were 31.8% (7/22) and 0, respectively. The complications included acute hydrocephalus (2 cases), visual acuity and visual field impairment (4 cases ), hemiparalysis (2 cases ), cranial nerves impairment (3 cases), sensory aphasia, pulmonary infection and gastrorrhagia. Conclusions Doing the psychological nursing well, enforcing the ward visits, eliminating the risk factors resulted in trauma and preventing the trauma preoperatively, monitoring the changes of breath and SpO2 closely, preventing or treating the complications such as cerebral hemorrhage and edema effectively, and carrying out early functional exercise of limbs and cranial nerves postoperatively are important for the patients' recovery. Key words: Meningiomas; Tentorial incisure; Nursing

CARDIOVASCULAR TOLERANCE IN UPPER GASTROINTESTINAL ENDOSCOPY USING AN ULTRATHIN SCOPE: PROSPECTIVE RANDOMIZED COMPARISON BETWEEN TRANSNASAL AND TRANSORAL PROCEDURES

Background: Transnasal esophagogastroduodenoscopy (EGD) has been suggested to be better tolerated by the cardiovascular system with a lower elevation of systolic blood pressure (BP) than oral EGD. However, limited information is available on the precise comparison of cardiovascular responses between the two endoscopic procedures using the same ultrathin scope.Methods: A prospective patient‐centered randomized study was performed to examine BP, pulse rate (P) and peripheral blood oxygen saturation (SpO2) during nasal and oral EGD using the same ultrathin endoscope. The acceptability of EGD was also assessed using a visual analog scale. A total of 1147 patients were divided into four groups: patients who preferred oral or nasal EGD underwent endoscopy according to their preference (preferred group) and patients without preference were randomly assigned to oral and nasal EGD (randomized group).Results: The study design excluded a bias of the patient's preference. The randomized group involved 149 patients among whom 74 and 75 cases were assigned to the transnasal and oral EGD groups, respectively. The results in the randomized group confirmed a significantly lower elevation of BP in patients undergoing transnasal EGD than those undergoing oral EGD, while the increase in P was slightly smaller in patients undergoing the nasal procedure. Changes in SpO2 were minimal in either procedure. Analyses of patient acceptability showed a favorable evaluation of nasal EGD.Conclusions: The present study confirmed less cardiovascular stress using nasal EGD than oral endoscopy when compared using the same ultrathin scope.

Preliminary report on surgical mask induced deoxygenation during major surgery

This study was undertaken to evaluate whether the surgeons' oxygen saturation of hemoglobin was affected by the surgical mask or not during major operations. Repeated measures, longitudinal and prospective observational study was performed on 53 surgeons using a pulse oximeter pre and postoperatively. Our study revealed a decrease in the oxygen saturation of arterial pulsations (SpO2) and a slight increase in pulse rates compared to preoperative values in all surgeon groups. The decrease was more prominent in the surgeons aged over 35. Considering our findings, pulse rates of the surgeon's increase and SpO2 decrease after the first hour. This early change in SpO2 may be either due to the facial mask or the operational stress. Since a very small decrease in saturation at this level, reflects a large decrease in PaO2, our findings may have a clinical value for the health workers and the surgeons.

Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse oximeters showed gradual decrease of saturations during induced hypoperfusion which demonstrate the direct relation between blood volumes (PPG amplitudes), arterial vessel stenosis and blood oxygen saturation. The custom made pulse oximeter was found to be more sensitive to SpO2 changes than the commercial pulse oximeter especially at high occluding pressures.

Auricall®. A new device for a non-invasive, wireless, continuous monitoring of oxygen saturation and heart rate in patients with heart failure

Sleep apnoea syndrome is frequent in patients with heart failure and associated with a worse prognosis. We evaluated a new device (Auricall®) for non-invasive, continuous recording of oxygen saturation (SpO 2) and heart rate (HR) in patients with heart failure. We studied 20 patients (mean age 48.43 ± 14.4 years, NYHA class II–III). All patients were requested to carry the device for at least 36 h and to write a diary during the recording time. Satisfactory recording of SpO 2 and HR was possible to obtain in 18 of 20 patients. Indeed 9 out of 18 patients showed significant periodic changes in SpO 2 during sleep. Therefore, Auricall® is a useful tool to non-invasively monitor SpO 2 and HR in patients with heart failure and to detect breathing disorders in these patients.

Cardiac output measurements during off-pump coronary surgery

Reply EDITOR: We thank Dr Renner and colleagues for their interest in our article and their comments. We are grateful for all input into the discussion about our article on cardiac output monitoring during off-pump coronary artery bypass (OPCAB) surgery. We agree with Dr Renner and colleagues that aortic transit-time ultrasound (ATTUS) cardiac output measurement is the true clinical gold standard for instantaneous cardiac output measurements. However, to our knowledge, in the case of OPCAB surgery, ATTUS has not yet been compared with other cardiac output measurement techniques. Indeed, continuous cardiac output measurements with either pulmonary artery catheter or partial CO2 rebreathing (PRCO) techniques do not provide continuous beat-to-beat assessment of cardiac output. Ideally, the best monitoring equipment should be non-invasive and beat-to-beat, and neither PRCO nor ATTUS achieve both of these ideals. Concerning ventilation during OPCAB surgery, our anaesthetists only exceptionally have to decrease tidal volume below 10 mL kg−1 in order to adjust to the needs of the surgeons. End-tidal CO2 is maintained by adjusting respiratory rate. As we mentioned in our article, no changes in cardiac output readings were observed, suggesting that acute haemodynamic events recorded by either method were related to changes in ventilatory settings. The differences in attitudes of surgeons and between institutions towards tidal volume during OPCAB surgery might be the reason why we were not concerned about the theoretical link of low tidal volume and inadequate rebreathing under our operating conditions. In addition, as mentioned by Tachibana and colleagues [1], the accuracy of the non-invasive cardiac output (NICO) technique can be maintained even at small tidal volumes if normocapnia is achieved by adjusting the respiratory rate. Conversely, the same authors also stated that the NICO underreports cardiac output at small tidal volumes. On the other hand, it is the variation of cardiac output which gives more information about acute haemodynamic changes than the absolute number itself. A disadvantage of underestimation of cardiac output could rather serve as an incentive to react quicker to haemodynamic changes. The assumption of a stable pulmonary capillary blood flow during NICO measurement cycles is indeed a drawback, and recalibration is needed in case of changes of SPO2 and FiO2. We stated that the NICO showed a faster response than the pulmonary artery catheter during OPCAB surgery. In fact, this statement was based on observation and it is correct to add that it has not been substantiated by any of our data. Bein and colleagues [2] correctly concluded that NICO as compared to ATTUS is not suitable for cardiac output determination during quickly changing haemodynamic conditions applicable to their setting of aortic reconstruction. However, to our knowledge ATTUS has neither been examined nor brought into practice as a monitoring tool for OPCAB surgery. Therefore, in this context, even with a delayed response time of 165 s, NICO still remains an interesting monitoring option for OPCAB surgery [3].

Ambulatory oxygen therapy assessment: a comparative study of incremental shuttle and 6-minute walking tests

Background Walking tests, such as the incremental shuttle walk test (ISWT) and the 6-minute walk test (6MWT), are recommended in the assessment of ambulatory oxygen for patients with chronic obstructive pulmonary disease (COPD). However, there is no evidence that these tests can be used interchangeably. Objectives To compare the ISWT and the 6MWT in COPD patients in terms of indication for ambulatory oxygen therapy. Design Crossover design. Setting Patients attended as outpatients. Participants Fifty patients with stable COPD (31 males; age 67 years, range 43 to 83 years); mean forced expiratory volume in 1 second 1.2 l [standard deviation (SD) 0.6 l] and 48.6% predicted (SD 23.4%). Intervention Patients performed both the ISWT and the 6MWT whilst breathing air. Breathlessness (Borg scale), percutaneous arterial oxygen saturation (SpO 2) and heart rate were measured before and after both tests. Main outcome measures Post-test SpO 2 and change from baseline. Results The mean change in saturation was −4.6% (SD 6.2%) and −2.8% (SD 5.3%) after the ISWT and the 6WMT, respectively. Using Bland and Altman plots, the limits of agreement for difference in change in SpO 2 (%) between the two tests were wide (−8.1 to 11.6) and clinically relevant. Sixteen patients (32%) and 13 patients (26%) met the criteria for ambulatory oxygen with the ISWT and the 6MWT, respectively ( P = 0.32). Conclusions This study found a wide variation between differences in exercise oxygen desaturation after the ISWT compared with the 6MWT, supporting the premise that these tests should not be used interchangeably in the assessment of ambulatory oxygen for COPD patients.

CARDIOVASCULAR TOLERANCE IN UNSEDATED UPPER GASTROINTESTINAL ENDOSCOPY: PROSPECTIVE RANDOMIZED COMPARISON BETWEEN TRANSNASAL AND CONVENTIONAL ORAL PROCEDURES

Background: The utility of transnasal esophagogastroduodenoscopy (EGD) using ultrathin endoscopy has previously been described by analyzing subjective information and comparing it to conventional oral EGD. Limited information is available regarding the advantageous use of nasal EGD when assessed by reliable objective data.Methods: A total of 927 patients undergoing unsedated EGD between June 2004 and May 2005 were enrolled. We used a partially randomized patient‐centered study design in order to exclude a bias of the patient’s preference. Patients were divided into four groups. Patients who preferred oral or nasal EGD underwent endoscopy according to their preference (preferred group). Patients without preference were randomly assigned to oral and nasal EGD (randomized group). Pulse, blood pressure (BP) and peripheral blood oxygen saturation (SpO2) were monitored during the procedure. Acceptability of EGD was also assessed by an acceptance score and the rate of willingness to repeat the same procedure.Results: Oral and nasal EGD were performed in 325 and 387 patients, respectively, in the preferred group, and 81 and 77 cases, respectively, in the randomized group. Nasal EGD was incomplete in 57 patients. Increases in BP were significantly lower in nasal EGD than in oral endoscopy in both the randomized and preferred groups, whereas no significant difference was found in the increment of pulse between the groups. Changes in SpO2 were minimal in either procedure. Analyses of patient acceptability showed favorable evaluation of nasal EGD in both randomized and preferred groups.Conclusions: Nasal EGD appears to be less stressful to the cardiovascular system. Patient’s acceptability also supports its usefulness unless difficulties in transnasal insertion are encountered.

Does End‐tidal Carbon Dioxide Monitoring Detect Respiratory Events Prior to Current Sedation Monitoring Practices?

The value of ventilation monitoring with end-tidal carbon dioxide (ETCO2) to anticipate acute respiratory events during emergency department (ED) procedural sedation and analgesia (PSA) is unclear. The authors sought to determine if ETCO2 monitoring would reveal findings indicating an acute respiratory event earlier than indicated by current monitoring practices. The study included a prospective convenience sample of ED patients undergoing PSA. Clinicians performed ED PSA procedures with generally accepted patient monitoring, including oxygen saturation (SpO2), and clinical ventilation assessment. A study investigator recorded ETCO2 levels and respiratory events during each PSA procedure, with clinical providers blinded to ETCO(2) levels. Acute respiratory events were defined as SpO2 < or =92%, increases in the amount of supplemental oxygen provided, use of bag-valve mask or oral/nasal airway for ventilatory assistance, repositioning or airway alignment maneuvers, and use of physical or verbal means to stimulate patients with depressed ventilation or apnea, and reversal agent administration. Enrollment was stopped after independent review of 20 acute respiratory events in 60 patient sedation encounters (33%). Abnormal ETCO2 findings were documented in 36 patients (60%). Seventeen patients (85%) with acute respiratory events demonstrated ETCO2 findings indicative of hypoventilation or apnea during PSA. Abnormal ETCO2 findings were documented before changes in SpO2 or clinically observed hypoventilation in 14 patients (70%) with acute respiratory events. Abnormal ETCO2 findings were observed with many acute respiratory events. A majority of patients with acute respiratory events had ETCO2 abnormalities that occurred before oxygen desaturation or observed hypoventilation.

Reference values for the 6-min walk test in healthy subjects 20–50 years old

In 102 healthy Caucasians, 20-50 years old, we investigated the effect of anthropometrics on the 6-min walk test (6MWT), in order to provide reference values for walk distance (6MWD), oxygen saturation (SpO2), pulse rate (PR), respiratory rate (RR), breathlessness perception (VAS) and for the walking distance and body weight product (DW). The mean 6MWD and DW values were 593 +/- 57 and 638+/-44 m (P < 0.01) and 35,030 +/- 5306 and 48,882 +/- 6555 kg m (P < 0.01), respectively for women and for men. While walking, SpO2 remained unaltered and subjects reached 67 +/- 10% of their maximal predicted heart rate and a RR mean value of 19 +/- 4 bpm. VAS ratings were significantly higher in females as compared to males (24 +/- 15 vs. 18 +/- 5 mm, P < 0.05), however, when corrected for PR change while walking, they were not different. The equation by stepwise multiple regression analysis included height, age and gender for the 6MWD and accounted for 42% of the total variance. This study confirms the relevant effect of anthropometrics on walking capacity and suggests that when rating dyspnea, the change in heart rate during walking should be considered.

Effect of Tramadol on Bispectral Index during Intravenous Anaesthesia with Propofol and Remifentanil

The aim of this study was to investigate the effects of tramadol on the Bispectral Index (BIS) during total intravenous propofol-remifentanil anaesthesia. Forty-four adult ASA Physical status I-II patients, scheduled for elective general surgical procedures were included in a prospective observational randomized study. Doses for anaesthetics and opioids were adjusted to keep the BIS value at 50 +/- 5. After 20 minutes of stable anaesthesia, the subjects were randomly allocated to receive intravenous saline (control group) or tramadol 1.5 mg/kg (tramadol group). BIS values, mean arterial pressure, and heart rate were recorded every five minutes for 20 minutes. Mean BIS values after tramadol administration were not significantly different from those following saline, throughout the observation period (P > 0.05). There were no patients in whom BIS values were more than 60 or who presented explicit recall of events under anaesthesia. There were no significant changes in mean arterial pressure, SpO2, or heart rate (P > 0.05). The results indicate that the administration of tramadol during stable total intravenous anaesthesia with propofol-remifentanil does not affect BIS values. The clinical relevance is that tramadol can be safely administered pre- and intraoperatively as pre-emptive or preventive analgesia without modification of the depth of anaesthesia.

Effect of Age on Bronchial Reactivity in Children with Asthma

In contrast to an abundance of data concerning age-related changes of bronchial sensitivity, the relationship between age and rapidity of bronchoconstriction (bronchial reactivity) remains unclear. We studied age and bronchial reactivity in children with asthma. Enrolled in this study were 511 asthmatic subjects and 115 age-matched control subjects 1 to 16 years of age. Bronchial reactivity was represented by the slope of the methacholine transcutaneous oxygen pressure dose-response curve (SPO2) in younger children and the slope of the respiratory resistance dose-response curve (SRrs) in older children. Overall, SPO2 and SRrs were higher in asthmatic than control subjects. SPO2 increased significantly from 1 to 6 years in asthmatic subjects, reaching a plateau after age 7. This age-related change in SPO2 also was seen in controls. SRrs in asthmatic subjects decreased after age 13, while SRrs in controls showed no significant change between age 7 and 16. Age-related change in bronchial reactivity occurs during childhood, possibly reflecting early changes in airway smooth muscle maturity and later changes in airway wall rigidity.

SpO2 change when newborn baby and baby's child seats are used

SpO2 change when newborn baby and baby's child seats are used

A preliminary study on the monitoring of mixed venous oxygen saturation through the left main bronchus

IntroductionThe study sought to assess the feasibility and accuracy of measuring mixed venous oxygen saturation (SvO2) through the left main bronchus (SpO2trachea)MethodsTwenty hybrid pigs of each sex were studied. After anesthesia, a Robertshaw double-lumen tracheal tube with a single-use pediatric pulse oximeter attached to the left lateral surface was introduced toward the left main bronchus of the pig by means of a fibrobronchoscope. Measurements of SpO2trachea and oxygen saturation from pulmonary artery samples (SvO2blood) were performed with an intracuff pressure of 0 to 60 cmH2O. After equilibration, hemorrhagic shock was induced in these pigs by bleeding to a mean arterial blood pressure of 40 mmHg. With the intracuff pressure maintained at 60 cmH2O, SpO2trachea and SvO2blood were obtained respectively during the pre-shock period, immediately after the onset of shock, 15 and 30 minutes after shock, and 15, 30, and 60 minutes after resuscitation.ResultsSpO2trachea was the same as SvO2blood at an intracuff pressure of 10, 20, 40, and 60 cmH2O, but was reduced when the intracuff pressure was zero (p < 0.001 compared with SvO2blood) in hemodynamically stable states. Changes of SpO2trachea and SvO2blood corresponded with varieties of cardiac output during the hemorrhagic shock period. There was a significant correlation between the two methods at different time points.ConclusionMeasurement of the left main bronchus SpO2 is feasible and provides similar readings to SvO2blood in hemodynamically stable or in low saturation states. Tracheal oximetry readings are not primarily derived from the tracheal mucosa. The technique merits further evaluation.

Ring-Shaped Pulse Oximeter and Its Application: Measurement of SpO2 and Blood Pressure During Sleep and During Flight

Respiratory and cardiovascular functions show circadian and day-to-day changes. We have developed a wireless ring-shaped pulse oximeter in collaboration with MC Medical Inc. and Advanced Medical Inc. We investigated the accuracy of this pulse oximeter and its application in daily life. Percutaneous arterial oxygen saturation (SpO2) of 47 volunteers was measured simultaneously with the ring-shaped pulse oximeter and a standard pulse oximeter. A total of 103 volunteers underwent measurement of SpO2 for 24 hr, and 11 healthy volunteers underwent measurement of SpO2 and blood pressure (BP) during flight. SpO2 and heart rate (HR) were measured and recorded every 20 sec, cabin barometric pressure and cabin oxygen concentration equivalent to sea level were measured minute-to-minute, and BP was measured every 3 min with a portable BP recorder during each flight. The SpO2 values measured with the ring-shaped pulse oximeter were similar to those measured with the standard method. The mean SpO2 during sleep was significantly lower in the group with high-normal BP or mild hypertension than in the group with normal BP. During flight, the mean change in SpO2 was -2.4 +/- 1.7% during nose-up flight, and 2.1 +/- 2.6% during nose-down flight. There was a significant correlation between change in SpO2 and change in systolic BP during nose-up flight. The wireless ring-shaped pulse oximeter was useful for investigating changes in SpO2 and its effect on BP in daily life during sleep and during air travel.

Ring-Shaped Pulse Oximeter and Its Application: Measurement of SpO2 and Blood Pressure During Sleep and During Flight

Respiratory and cardiovascular functions show circadian and day-to-day changes. We have developed a wireless ring-shaped pulse oximeter in collaboration with MC Medical Inc. and Advanced Medical Inc. We investigated the accuracy of this pulse oximeter and its application in daily life. Percutaneous arterial oxygen saturation (SpO2) of 47 volunteers was measured simultaneously with the ring-shaped pulse oximeter and a standard pulse oximeter. A total of 103 volunteers underwent measurement of SpO2 for 24 hr, and 11 healthy volunteers underwent measurement of SpO2 and blood pressure (BP) during flight. SpO2 and heart rate (HR) were measured and recorded every 20 sec, cabin barometric pressure and cabin oxygen concentration equivalent to sea level were measured minute-to-minute, and BP was measured every 3 min with a portable BP recorder during each flight. The SpO2 values measured with the ring-shaped pulse oximeter were similar to those measured with the standard method. The mean SpO2 during sleep was significantly lower in the group with high-normal BP or mild hypertension than in the group with normal BP. During flight, the mean change in SpO2 was − 2.4 ± 1.7% during nose-up flight, and 2.1 ± 2.6% during nose-down flight. There was a significant correlation between change in SpO2 and change in systolic BP during nose-up flight. The wireless ring-shaped pulse oximeter was useful for investigating changes in SpO2 and its effect on BP in daily life during sleep and during air travel.