scholarly journals Measuring Biexponential Transverse Relaxation of the ASL Signal at 9.4 T to Estimate Arterial Oxygen Saturation and the Time of Exchange of Labeled Blood Water into Cortical Brain Tissue

2012 ◽  
Vol 33 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Jack A Wells ◽  
Bernard Siow ◽  
Mark F Lythgoe ◽  
David L Thomas
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Transverse Relaxation ◽  
Exchange Time ◽  
Relative Contribution ◽  
A Value ◽  
Tissue Space ◽  
Biexponential Model ◽  
The Mean

The transverse decay of the arterial spin labeling (ASL) signal was measured at four inflow times in the rat brain cortex at 9.4 T. Biexponential T2 decay was observed that appears to derive from different T2 values associated with labeled water in the intravasculature (IV) and extravascular (EV) compartments. A two compartment biexponential model was used to assess the relative contribution of the IV and EV compartments to the ASL signal, without assuming a value for T2 of labeled blood water in the vessels. This novel methodology was applied to estimate the exchange time of blood water into EV tissue space and the oxygen saturation of blood on the arterial side of the vasculature. The mean exchange time of labeled blood water was estimated to be 370 ± 40 ms. The oxygen saturation of the arterial side of the vasculature was significantly less than 100% (~85%), which may have implications for quantitative functional magnetic resonance imaging studies where the arterial oxygen saturation is frequently assumed to be 100%.

Two patterns of daily hypoxic exposure and their effects on measures of chemosensitivity in humans

2007 ◽  
Vol 103 (6) ◽  
pp. 1973-1978 ◽  
Author(s):  
Michael S. Koehle ◽  
A. William Sheel ◽  
William K. Milsom ◽  
Donald C. McKenzie
Keyword(s):  
Oxygen Saturation ◽  
Intermittent Hypoxia ◽  
Ventilatory Response ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Hypoxic Exposure ◽  
Hypoxic Ventilatory Response ◽  
The Third ◽  
Long Duration ◽  
The Mean

The purpose of this study was to compare chemoresponses following two different intermittent hypoxia (IH) protocols in humans. Ten men underwent two 7-day courses of poikilocapnic IH. The long-duration IH (LDIH) protocol consisted of daily 60-min exposures to normobaric 12% O2. The short-duration IH (SDIH) protocol comprised twelve 5-min bouts of 12% O2, separated by 5-min bouts of room air, daily. Isocapnic hypoxic ventilatory response (HVR) was measured daily during the protocol and 1 and 7 days following. Hypercapnic ventilatory response (HCVR) and CO2 threshold and sensitivity (by the modified Read rebreathing technique) were measured on days 1, 8, and 14. Following 7 days of IH, the mean HVR was significantly increased from 0.47 ± 0.07 and 0.47 ± 0.08 to 0.70 ± 0.06 and 0.79 ± 0.06 l·min−1·%SaO2−1 (LDIH and SDIH, respectively), where %SaO2 is percent arterial oxygen saturation. The increase in HVR reached a plateau after the third day. One week post-IH, HVR values were unchanged from baseline. HCVR increased from 3.0 ± 0.4 to 4.0 ± 0.5 l·min−1·mmHg−1. In both the hyperoxic and hypoxic modified Read rebreathing tests, the slope of the CO2/ventilation plot was unchanged by either intervention, but the CO2/ventilation curve shifted to the left following IH. There were no correlations between the changes in response to hypoxia and hypercapnia. There were no significant differences between the two IH protocols for any measures, indicating that comparable changes in chemoreflex control occur with either protocol. These results also suggest that the two methods of measuring CO2 response are not completely concordant and that the changes in CO2 control do not correlate with the increase in the HVR.

Quantification of adult cerebral hemodynamics by near-infrared spectroscopy

1994 ◽  
Vol 77 (6) ◽  
pp. 2753-2760 ◽  
Author(s):  
C. E. Elwell ◽  
M. Cope ◽  
A. D. Edwards ◽  
J. S. Wyatt ◽  
D. T. Delpy ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Cerebral Hemodynamics ◽  
Arterial Oxygen ◽  
The Mean

Near-infrared spectroscopy was used to measure global cerebral blood flow and volume in 10 healthy adult volunteers. High- and low-cerebral blood flow compartments were detected with mean flows for all 10 subjects of 59 +/- 21 (SD) and 11 +/- 4 ml.100 g-1.min-1, respectively. The mean cerebral blood volume of the group was 2.85 +/- 0.97 ml/100 g. Analysis of spontaneous changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin demonstrated strong correlations between respiratory rate and the oscillation frequency of cerebral oxyhemoglobin concentration (r = 0.99) and arterial oxygen saturation (SaO2) (r = 0.99). An estimate of the mean cerebral oxygen saturation for all subjects averaged 59.4 +/- 12.4% when their mean SaO2 was 91.8 +/- 2.4% (equivalent to 67.6 +/- 13.8% at a normoxic SaO2 of 98%). These results demonstrate that near-infrared spectroscopy can be used as a noninvasive bedside technique for both qualitative and quantitative evaluation of cerebral hemodynamics and oxygenation in adults.

scholarly journals The Effect of Adjunctive use of Dexmedetomidine and Metoral with Thiopental on Hemodynamic Status, Agitation, and Patient Satisfaction in Patients with Mood Disorders after Electroconvulsive Therapy

2020 ◽  
Vol 8 (B) ◽  
pp. 329-333
Author(s):  
Talat Mohammadi ◽  
Hamidreza Jamilian ◽  
Anita Alaghemand ◽  
Alireza Kamali
Keyword(s):  
Patient Satisfaction ◽  
Oxygen Saturation ◽  
Mood Disorders ◽  
Electroconvulsive Therapy ◽  
Recovery Time ◽  
Arterial Oxygen Saturation ◽  
The Other ◽  
Arterial Oxygen ◽  
Hemodynamic Status ◽  
The Mean

AIM: The aim of our study was to determine the effect of adjunctive use of dexmedetomidine and metoral with thiopental on hemodynamic status, agitation, patient satisfaction, and duration of seizure in patients with mood disorders in electroconvulsive therapy (ECT). METHODS: This study is a randomized, double-blind, clinical trial. Sixty patients (18–60 years) according to DSM5 criteria had mood disorder and were candidates for ECT. Patients were randomly divided into two groups of 30 each. One group received 5.0 μg/kg dexmedetomidine 10 min before induction of thiopental, and the other group received 5.2 mg intravenous metoprolol immediately before ECT. Patients’ satisfaction, duration of seizure, and arterial oxygen saturation were evaluated. RESULTS: The mean age of both groups was approximately 37 years with the majority of men. No significant difference was found between the two groups in terms of age and sex, blood pressure (BP), heart rate (HR), duration of seizure, and arterial oxygen saturation before ECT. The mean BP and HR in the recovery were lower in the dexmedetomidine group than in the metoral group. Arterial oxygen saturation percentage was not significantly different between the two groups. The recovery time in the dexmedetomidine group was longer than the metoral group (p = 0.001). Post-ECT satisfaction was found to be higher in the dexmedetomidine group than in the metoral group and the mean agitation score was found to be higher in the metoral group. CONCLUSION: Both metoral and dexmedetomidine as adjuvants decrease the hyperdynamic responses of patients after ECT, whereas the effect of dexmedetomidine is more than metoral; on the other hand, neither dexmedetomidine nor metoral has any negative effect on seizure duration, but dexmedetomidine significantly prolonged recovery time as compared to metoral.

scholarly journals The Effect of the Duration of Pre-Oxygenation before Endotracheal Suction on Hemodynamic Symptoms

2016 ◽  
Vol 9 (2) ◽  
pp. 127
Author(s):  
Hossein Tavangar ◽  
Mostafa Javadi ◽  
Saeed Sobhanian ◽  
Fatemeh Forozan Jahromi
Keyword(s):  
Heart Rate ◽  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Repeated Measure ◽  
Arterial Oxygen ◽  
Endotracheal Suctioning ◽  
Endotracheal Suction ◽  
The Mean ◽  
The One ◽  
Clinical Conditions

<p><strong>BACKGROUND:</strong> Hypoxia and hypoxemia are among the most common complications of endotracheal suctioning. These complications are often mitigated by the administration of oxygen 100% prior to endotracheal suction. Although several studies have supported the application of this method, none have yet specified the exact duration of pre-oxygenation required to be performed before endotracheal suction. The present study was therefore conducted to determine the effect of the duration of pre-oxygenation before endotracheal suction on heart rate and arterial oxygen saturation in patients in intensive care units.</p><p><strong>OBJECTIVES:</strong> This prospective clinical trial conducted on 63 eligible ICU patients under mechanical ventilator. Subjects randomly divided into three groups. Pre-oxygenation was carried out for 30 seconds in the first group, for one minute in the second group and for two minutes in the third group. All three groups were then hyper-oxygenated for one minute. Arterial oxygen saturation and heart rate were recorded on different occasions in the three groups. The data obtained were analyzed using the ANOVA, the one-way ANOVA, the post-hoc test and the repeated measure ANOVA.</p><p><strong>RESULTS:</strong> The results obtained showed a greater reduction in the mean O2sat during the suctioning episodes in the 30-second pre-oxygenation group compared to in the one-minute (P=0.046) and two-minute (P=0.001) pre-oxygenation groups. This mean reduction was also observed immediately after suctioning (P=0.001). The mean O2sat was lower in the 30-second pre-oxygenation group than in the one-minute pre-oxygenation group in minutes 5 (P=0.002) and 20 (P=0.001) of the suctioning. Similarly, the mean O2sat was lower in the 30-second pre-oxygenation group than in the two-minute pre-oxygenation group in minutes 5 (P=0.001) and 20 (P=0.001) of the suctioning. The results obtained through the ANOVA showed the lack of significant differences between the three groups in the mean variation in heart rate in the different stages of suctioning.</p><p><strong>CONCLUSIONS:</strong> According to the results obtained, one-minute and two-minute pre-oxygenations cause less disruption in arterial oxygen saturation compared to a 30-second pre-oxygenation. To achieve stability in arterial oxygen saturation and avoid hypoxemia caused by endotracheal suctioning, one-minute or two-minute pre-oxygenation is recommended in ICUs depending on the patient’s clinical conditions.</p>

scholarly journals Study of Oxygen Saturation by Pulse Oximetry and Arterial Blood Gas in ICU Patients: A Descriptive Cross-sectional Study

2020 ◽  
Vol 58 (230) ◽  
Author(s):  
Nabin Rauniyar ◽  
Shyam Pujari ◽  
Pradeep Shrestha
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Arterial Oxygen Saturation ◽  
Cross Sectional Study ◽  
Arterial Oxygen ◽  
Blood Gas ◽  
Cross Sectional ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
The Mean

Introduction: Pulse oximetery is expected to be an indirect estimation of arterial oxygen saturation. However, there often are gaps between SpO2 and SaO2. This study aims to study on arterial oxygen saturation measured by pulse oximetry and arterial blood gas among patients admitted in intensive care unit. Methods: It was a hospital-based descriptive cross-sectional study in which 101 patients meeting inclusion criteria were studied. SpO2 and SaO2 were measured simultaneously. Mean±SD of SpO2 and SaO2 with accuracy, sensitivity and specificity were measured. Results: According to SpO2 values, out of 101 patients, 26 (25.7%) were hypoxemic and 75 (74.25%) were non–hypoxemic. The mean±SD of SaO2 and SpO2 were 93.22±7.84% and 92.85±6.33% respectively. In 21 patients with SpO2<90%, the mean±SD SaO2 and SpO2 were 91.63±4.92 and 87.42±2.29 respectively. In 5 patients with SpO2 < 80%, the mean ± SD of SaO2 and SpO2 were: 63.40±3.43 and 71.80±4.28, respectively. In non–hypoxemic group based on SpO2 values, the mean±SD of SpO2 and SaO2 were 95.773±2.19% and 95.654±3.01%, respectively. The agreement rate of SpO2 and SaO2 was 83.2%, and sensitivity and specificity of PO were 84.6% and 83%, respectively. Conclusions: Pulse Oximetry has high accuracy in estimating oxygen saturation with sp02>90% and can be used instead of arterial blood gas.

scholarly journals Epidemiological Study of Patients with COVID-19 in Iran (Markazi Province)

2021 ◽  
Author(s):  
Alireza Kamali ◽  
Behnam Mahmoodieh ◽  
Mohammad Jamalian ◽  
Ahmad Amani ◽  
Alireza Jahangirifard
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Underlying Disease ◽  
Epidemiological Studies ◽  
Arterial Oxygen ◽  
Number Of Patients ◽  
Significant Difference ◽  
History Of ◽  
The Mean ◽  
Severity Of The Disease

Background: The increasing prevalence of SARS-COV-2 infection necessitates further epidemiological studies in the field of this epidemic. Methods: during 66 days (20/02/2020 to 01/06/2020) all patients diagnosed with SARS-COV-2 infection referred to Valiasr Hospital in Arak were monitored. Thus, based on the pre-prepared questionnaire, the information of the mentioned patients was extracted from the Hospital Information System (HIS) by the required formats and after eliminating the incomplete cases, it was aggregated based on coding (to preserve the patients' information). The results were evaluated using spss. v25 software. Results: Out of 535 patients with SARS-COV-2 included in the study, 295 (55%) were male and 240 (45%) were female. Women with a mean age of 61.03 years were significantly (p = 0.009) at a higher age than men with a mean age of 56.59 years. Nearly 60% (304 patients) of patients had a history of underlying disease. Gender comparison of patients with a history of underlying disease infected with SARS-COV-2 infection did not show any significant difference between male and female patients. Comparison of the mean age of the improved and dead patients shows that the mean age of the dead patients with a significant difference (P <0.001) was higher than the improved subjects. This result is also true for people with a history of underlying disease (p<0.0001). The number of patients with arterial oxygen saturation <93% was significantly higher in the group of patients with a history of at least one chronic underlying disease than who did not have any chronic disease (P <0.0001). The mortality rate in ICU patients was significantly higher than those admitted to the normal ward (p < 0.0001). Conclusion: Aging, gender, underlying diseases and arterial oxygen saturation (<93%) at the time of admission have important role in the hospitalization rate, severity of the disease and mortality in patients with COVID-19.

OXIMETER STUDIES IN NEWBORN INFANTS DURING CRYING

PEDIATRICS ◽  
1952 ◽  
Vol 9 (6) ◽  
pp. 756-763 ◽  
Author(s):  
KLARA J. PREC ◽  
DONALD E. CASSELS
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Pulmonary Ventilation ◽  
Newborn Infants ◽  
Arterial Oxygen ◽  
Direct Reading ◽  
Single Scale ◽  
The Mean ◽  
Alveolar Oxygen ◽  
The Right

The arterial oxygen saturation was determined in 135 healthy newborn infants during sleep and while crying with a direct reading single scale oximeter. In the first group, consisting of infants from one hour and 30 minutes to 3 days of age, 66% showed a decrease of oxygen saturation with crying, 27% an increase and 6.8% no change. In the second group, which includes all infants between 4 and 9 days of age, 59% showed an increase in saturation with crying, 21% a decrease and 22.4% no change. In comparison, the mean results in these two groups are in the opposite direction. These changes are statistically significant. Twenty-eight infants were studied also while breathing oxygen (73%-98.5%), and the results compared with those in room air were found to show an identical trend. It is concluded that increases in arterial oxygen saturation with crying, which occur most frequently in older infants, are probably due to an increase in alveolar oxygen tension secondary to improved pulmonary ventilation during crying. The paradoxic decrease in saturation during crying, which was found in a large percentage of infants of the younger group, is suggestive of the presence of a transitory venous-arterial shunt. This shunt could be either through atelectatic areas of the lung or through the foramen ovale, which is only functionally closed and can open whenever the pressure in the right auricle exceeds the left auricular pressure. There is some available evidence to support the latter possibility.

Efficacy and safety of balloon dilation as palliative treatment for tetralogy of Fallot

1994 ◽  
Vol 4 (3) ◽  
pp. 255-261 ◽  
Author(s):  
Gurleen K. Sharland ◽  
Shakeel A. Qureshi ◽  
Edmund J. Ladusans ◽  
Jonathon M. Parsons ◽  
Edward J. Baker ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Tetralogy Of Fallot ◽  
Pulmonary Valve ◽  
Arterial Oxygen Saturation ◽  
Balloon Dilation ◽  
Right Ventricular Outflow Tract ◽  
Outflow Tract ◽  
Arterial Oxygen ◽  
The Mean ◽  
The Right

AbstractTwenty-six patients requiring palliation for the tetralogy of Fallot were treated by balloon dilation. The mean age at dilation was 8.5 months (range 0.5−20.6) and the mean weight 6.7 kg (range 2.6−10.7). Successful dilation was achieved in 25 patients. The mean ratio of the balloon to the diameter of the pulmonary outflow tract was 1.6 (range 1.2−2.0). The aortic oxygen saturation increased from mean±SD of 80±12.4% before to 91±4.3% after dilation (p<0.05). The pulmonary arterial oxygen saturation rose from 64±10.7% to 80±7.7% (p<0.05). Transient hypotension and arterial desaturation were noted in 19 patients during inflation of the balloon. One patient had a cardiac arrest prior to dilation and died afterwards. Seven patients had cyanotic spells related to the procedure. Attempts to cross the pulmonary valve resulted in infundibular perforation by the guide wire in one patient. Of the 24 survivors who initially had successful dilation procedures, three have needed a Blalock-Taussig shunt. Palliation without a shunt was achieved in the remaining 21 patients. In 12 patients, repeat angiography, 2.5−20 months (mean 9.1) after dilation, showed an increase in the diameter of the outflow tract from 7.1±2.1 mm before to 9.5±2.0 mm after dilation (p<0.05). Diameters of the pulmonary arteries increased from 6.3±2.2 mm on the right and 6.8±1.9 mm on the left before to 9.2±2.2 mm and 9.3±2.5 mm respectively after dilation (p<0.05 for both branches). Surgical correction has been achieved in 22 patients, 21 of these 2−22 months after balloon dilation and the other patient 20 months after construction of a shunt. At operation, the leaflets of the pulmonary valve were noted to be torn in five patients. In 12 patients, there was extensive scarring of the infundibulum. Balloon dilation of the right ventricular outflow tract achieves adequate palliation and may result in an increase in the diameter of the pulmonary valve and branches of the pulmonary trunk. It should be considered as an alternative to shunt procedures in children with tetralogy of Fallot.

Psychophysiological Responses of Pilots in Hypoxia Training at 7000 and 7500 m

2020 ◽  
Vol 91 (10) ◽  
pp. 785-789
Author(s):  
Dongqing Wen ◽  
Lei Tu ◽  
Guiyou Wang ◽  
Zhao Gu ◽  
Weiru Shi ◽  
...  
Keyword(s):  
Heart Rate ◽  
Psychomotor Performance ◽  
Physiological Responses ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Awareness Training ◽  
Similar Frequency ◽  
Psychophysiological Responses ◽  
The Mean ◽  
Training Protocol

INTRODUCTION: We compared the physiological responses, psychomotor performances, and hypoxia symptoms between 7000 m and 7500 m (23,000 and 24,600 ft) exposure to develop a safer hypoxia training protocol.METHODS: In altitude chamber, 66 male pilots were exposed to 7000 and 7500 m. Heart rate and arterial oxygen saturation were continuously monitored. Psychomotor performance was assessed using the computational task. The hypoxic symptoms were investigated by a questionnaire.RESULTS: The mean duration time of hypoxia was 323.0 56.5 s at 7000 m and 218.2 63.3 s at 7500 m. The 6-min hypoxia training was completed by 57.6% of the pilots and 6.1% of the pilots at 7000 m and at 7500 m, respectively. There were no significant differences in pilots heart rates and psychomotor performance between the two exposures. The Spo2 response at 7500 m was slightly severer than that at 7000 m. During the 7000 m exposure, pilots experienced almost the same symptoms and similar frequency order as those during the 7500 m exposure.CONCLUSIONS: There were concordant symptoms, psychomotor performance, and very similar physiological responses between 7000 m and 7500 m during hypoxia training. The results indicated that 7000-m hypoxia awareness training might be an alternative to 7500-m hypoxia training with lower DCS risk and longer experience time.Wen D, Tu L, Wang G, Gu Z, Shi W, Liu X. Psychophysiological responses of pilots in hypoxia training at 7000 and 7500 m. Aerosp Med Hum Perform. 2020; 91(10):785789.

Outcomes of the Extracardiac Fontan Procedure Using Cardiopulmonary Bypass: Early Results

2014 ◽  
Vol 17 (3) ◽  
pp. 173 ◽  
Author(s):  
Murat Ugurlucan ◽  
Eylem Yayla Tuncer ◽  
Fusun Guzelmeric ◽  
Eylul Kafali ◽  
Omer Ali Sayin ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Fontan Procedure ◽  
Fontan Operation ◽  
Arterial Oxygen Saturation ◽  
Vena Cava ◽  
Arterial Oxygen ◽  
Shunt Operation ◽  
Early Results ◽  
The Mean ◽  
Extracardiac Fontan

<p><strong>Background</strong>: Although the avoidance of cardiopulmonary bypass during the Fontan procedure has potential advantages, using cardiopulmonary bypass during this procedure has no adverse effects in terms of morbidity and mortality rates. In this study, we assessed the postoperative outcomes of our first 9 patients who have undergone extracardiac Fontan operation by the same surgeon using cardiopulmonary bypass.</p><p><strong>Methods</strong>: Between September 2011 and April 2013,  9 consecutive patients (3 males and 6 females) underwent extra-cardiac Fontan operation. All operations were performed under cardiopulmonary bypass at normothermia by the same surgeon.  The age of patients ranged between 4 and 17 (9.8 ± 4.2) years. Previous operations performed on these patients were modified Blalock-Taussig shunt procedure in 2 patients, bidirectional cavopulmonary shunt operation in 6 patients, and pulmonary arterial banding in 1 patient. Except 2 patients who required intracardiac intervention, cross-clamping was not applied. In all patients, the extracardiac Fontan procedure was carried out by interposing an appropriately sized tube graft between the infe-rior vena cava and right pulmonary artery.</p><p><strong>Results</strong>: The mean intraoperative Fontan pressure and transpulmonary gradient were 12.3 ± 2.5 and 6.9 ± 2.2 mm Hg, respectively. Intraoperative fenestration was not required. There was no mortality and 7 patients were discharged with-out complications. Complications included persistent pleural effusion in 1 patient and a transient neurological event in 1 patient. All patients were weaned off mechanical ventila-tion within 24 hours. The mean arterial oxygen saturation increased from 76.1% ± 5.3% to 93.5% ± 2.2%. All patients were in sinus rhythm postoperatively. Five patients required blood and blood-product transfusions. The mean intensive care unit and hospital stay periods were 2.9 ± 1.7 and 8.2 ±  1.9 days, respectively.</p><p><strong>Conclusions</strong>: The extracardiac Fontan operation per-formed using cardiopulmonary bypass provides satisfactory results in short-term follow-up and is associated with favor-able postoperative hemodynamics and morbidity rates.</p>

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