Effect of acetazolamide on leg endurance exercise at sea level and simulated altitude

2006 ◽  
Vol 110 (6) ◽  
pp. 683-692 ◽  
Author(s):  
Charles S. Fulco ◽  
Steven R. Muza ◽  
Dan Ditzler ◽  
Eric Lammi ◽  
Steven F. Lewis ◽  
...  
Keyword(s):  
Sea Level ◽  
Arterial Oxygen Saturation ◽  
Acute Mountain Sickness ◽  
Endurance Performance ◽  
Knee Extension ◽  
Arterial Oxygen ◽  
Simulated Altitude ◽  
Double Blind ◽  
Constant Work Rate ◽  
Knee Extension Exercise

Acetazolamide can be taken at sea level to prevent acute mountain sickness during subsequent altitude exposure. Acetazolamide causes metabolic acidosis at sea level and altitude, and increases SaO2 (arterial oxygen saturation) at altitude. The aim of the present study was to determine whether acetazolamide impairs muscle endurance at sea level but not simulated altitude (4300 m for <3 h). Six subjects (20±1 years of age; mean±S.E.M.) performed exhaustive constant work rate one-leg knee-extension exercise (25±2 W) once a week for 4 weeks, twice at sea level and twice at altitude. Each week, subjects took either acetazolamide (250 mg) or placebo orally in a double-blind fashion (three times a day) for 2 days. On day 2, all exercise bouts began approx. 2.5 h after the last dose of acetazolamide or placebo. Acetazolamide caused similar acidosis (pH) in all subjects at sea level (7.43±0.01 with placebo compared with 7.34±0.01 with acetazolamide; P<0.05) and altitude (7.48±0.03 with placebo compared with 7.37±0.01 with acetazolamide; P<0.05). However, endurance performance was impaired with acetazolamide only at sea level (48±4 min with placebo compared with 36±5 min with acetazolamide; P<0.05), but not altitude (17±2 min with placebo compared with 20±3 min with acetazolamide; P=not significant). In conclusion, lack of impairment of endurance performance by acetazolamide compared with placebo at altitude was probably due to off-setting secondary effects resulting from acidosis, e.g. ventilatory induced increase in SaO2 for acetazolamide compared with placebo (89±1 compared with 86±1% respectively; P<0.05), which resulted in an increased oxygen pressure gradient from capillary to exercising muscle.

scholarly journals Morphine for Postoperative Analgesia. A Comparison of Intramuscular and Subcutaneous Routes of Administration

1996 ◽  
Vol 24 (5) ◽  
pp. 574-578 ◽  
Author(s):  
I. M. Cooper
Keyword(s):  
Postoperative Analgesia ◽  
Intramuscular Injection ◽  
Arterial Oxygen Saturation ◽  
Subcutaneous Administration ◽  
Arterial Oxygen ◽  
Patient Acceptance ◽  
Subcutaneous Route ◽  
Double Blind ◽  
Routes Of Administration ◽  
Pain Scores

Intermittent parenteral bolus doses of morphine are commonly used for postoperative analgesia. Morphine is typically given by intramuscular or intravenous injection but there are theoretical advantages for the subcutaneous route of administration. Fifty-nine patients entered a prospective randomized double-blind cross-over study comparing intermittent intramuscular and subcutaneous morphine boluses. Patients received 0.15 mg/kg of morphine by subcutaneous or intramuscular injection. They were reviewed at the time of injection, after 15 minutes and each hour for four hours. The majority of patients indicated a strong preference for the subcutaneous route. There were no significant differences in pain scores, respiratory rate, arterial oxygen saturation, heart rate, mean arterial pressure, sedation or nausea scores between intramuscular and subcutaneous administration of morphine. Postoperative analgesia by subcutaneous morphine bolus injection is as effective as intramuscular injection with a similar side-effect profile but with greater patient acceptance and less risk.

scholarly journals Erythropoiesis in women during 11 days at 4,300 m is not affected by menstrual cycle phase

2001 ◽  
Vol 91 (6) ◽  
pp. 2579-2586 ◽  
Author(s):  
John T. Reeves ◽  
Stacy Zamudio ◽  
Thomas E. Dahms ◽  
Ingrid Asmus ◽  
Barry Braun ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Oxygen Saturation ◽  
Cell Volume ◽  
Sea Level ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Cycle Phase ◽  
Red Cell ◽  
Menstrual Cycle Phase ◽  
Red Cell Volume

Because the ovarian steroid hormones, progesterone and estrogen, have higher blood levels in the luteal (L) than in the follicular (F) phase of the menstrual cycle, and because of their known effects on ventilation and hematopoiesis, we hypothesized that less hypoxemia and less erythropoiesis would occur in the L than the F phase of the cycle after arrival at altitude. We examined erythropoiesis with menstrual cycle phase in 16 women (age 22.6 ± 0.6 yr). At sea level, 11 of 16 women were studied during both menstrual cycle phases, and, where comparison within women was available, cycle phase did not alter erythropoietin ( n= 5), reticulocyte count ( n = 10), and red cell volume ( n = 9). When all 16 women were taken for 11 days to 4,300-m altitude (barometric pressure = 462 mmHg), paired comparisons within women showed no differences in ovarian hormone concentrations at sea level vs. altitude on menstrual cycle day 3 or 10 for either the F ( n = 11) or the L ( n = 5) phase groups. Arterial oxygen saturation did not differ between the F and L groups at altitude. There were no differences by cycle phase on day 11 at 4,300 m for erythropoietin [22.9 ± 4.7 (L) vs. 18.8 ± 3.4 mU/ml (F)], percent reticulocytes [1.9 ± 0.1 (L) vs. 2.1 ± 0.3% (F)], hemoglobin [13.5 ± 0.3 (L) vs. 13.7 ± 0.3 g/100 ml (F)], percent hematocrit [40.6 ± 1.4 (L) vs. 40.7 ± 1.0% (F)], red cell volume [31.1 ± 3.6 (L) vs. 33.0 ± 1.6 ml/kg (F)], and blood ferritin [8.9 ± 1.7 (L) vs. 10.2 ± 0.9 μg/l (F)]. Blood level of erythropoietin was related ( r= 0.77) to arterial oxygen saturation but not to the levels of progesterone or estradiol. We conclude that erythropoiesis was not altered by menstrual cycle phase during the first days at 4,300-m altitude.

P6480Asymmetric dimethylarginine (ADMA) predicts altitude-associated hypoxic pulmonary arterial hypertension

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
R H Boeger ◽  
P Siques ◽  
J Brito ◽  
E Schwedhelm ◽  
E Pena ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Logistic Regression ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Sea Level ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Arterial Blood ◽  
Pulmonary Arterial

Abstract Prolonged exposure to altitude-associated chronic hypoxia (CH) may cause high altitude pulmonary hypertension (HAPH). Chronic intermittent hypobaric hypoxia (CIH) occurs in individuals who commute between sea level and high altitude. CIH is associated with repetitive acute hypoxic acclimatization and conveys the long-term risk of HAPH. As nitric oxide (NO) is an important regulator of systemic and pulmonary vascular tone and asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis that increases in hypoxia, we aimed to investigate whether ADMA predicts the incidence of HAPH among Chilean frontiers personnel exposed to six months of CIH. We performed a prospective study of 123 healthy male subjects who were subjected to CIH (5 days at appr. 3,550 m, followed by 2 days at sea level) for six months. ADMA, SDMA, L-arginine, arterial oxygen saturation, systemic arterial blood pressure, and haematocrit were measured at baseline and at months 1, 4, and 6 at high altitude. Acclimatization to high altitude was determined using the Lake Louise Score and the presence of acute mountain sickness (AMS). Echocardiography was performed after six months of CIH in a subgroup of 43 individuals with either good (n=23) or poor (n=20) aclimatization to altitude, respectively. Logistic regression was used to assess the association of biomarkers with HAPH. 100 study participants aged 18.3±1.3 years with complete data sets were included in the final analysis. Arterial oxygen saturation decreased upon the first ascent to altitude and plateaued at about 90% during the further course of the study. Haematocrit increased to about 47% after one month and remained stable thereafter. ADMA continuously increased and SDMA decreased during the study course, whilst L-arginine levels showed no distinct pattern. The incidence of AMS and the Lake Louise Score were high after the first ascent (53 and 3.1±2.4, respectively) and at one month of CIH (47 and 3.0±2.6, respectively), but decreased to 20 and 1.4±2.0 at month 6, respectively (both p<0.001 for trend). In echocardiography, 18 participants (42%) showed a mean pulmonary arterial pressure (mPAP) greater than 25 mm Hg (mean ± SD, 30.4±3.9 mm Hg), out of which 9 (21%) were classified as HAPH (mPAP ≥30 mm Hg; mean ± SD, 33.9±2.2 mm Hg). Baseline ADMA, but not SDMA, was significantly associated with mPAP at month 6 in univariate logistic regression analysis (R = 0.413; p=0.007). In ROC analysis, a cut-off for baseline ADMA of 0.665 μmol/l was determined as the optimal cut-off level to predict HAPH (mPAP >30 mm Hg) with a sensitivity of 100% and a specificity of 63.6%. ADMA concentration increases during long-term CIH. It is an independent predictive biomarker for the incidence of HAPH. SDMA concentration decreases during CIH and shows no association with HAPH. Our data support a role of impaired NO-mediated pulmonary vasodilation in the pathogenesis of high altitude pulmonary hypertension. Acknowledgement/Funding CONICYT/FONDEF/FONIS Sa 09I20007; FIC Tarapaca BIP 30477541-0; BMBF grant 01DN17046 (DECIPHER); Georg & Jürgen Rickertsen Foundation, Hamburg

Angiotensin Converting Enzyme Response to Hypoxia in Man: Its Role in Altitude Acclimatization

1984 ◽  
Vol 67 (4) ◽  
pp. 453-456 ◽  
Author(s):  
J. S. Milledge ◽  
D. M. Catley
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Oxygen Saturation ◽  
Human Subjects ◽  
Arterial Oxygen Saturation ◽  
Venous Blood ◽  
Acute Mountain Sickness ◽  
Arterial Oxygen ◽  
Converting Enzyme ◽  
Ace Activity ◽  
Mountain Sickness

1. The response of serum angiotensin converting enzyme (ACE) activity to three grades of hypoxia was studied in two groups of human subjects. Hypoxic gas mixtures having oxygen concentrations of 14, 12.6 and 10.4% were breathed successively for a period of 10 min at each concentration. Venous blood was sampled at the end of each of the three periods and arterial oxygen saturation was recorded throughout the experiment. 2. The subjects were selected as being ‘good’ or ‘poor’ acclimatizers according to their history of acute mountain sickness. There were five subjects in each group. 3. Hypoxia resulted in a reduction in ACE activity in both groups, the reduction being linear with respect to arterial oxygen saturation. 4. The reduction in ACE activity was greater in the good acclimatizer group as shown by a significantly greater slope of the response line of ACE activity to arterial oxygen saturation. 5. The significance of this finding in relation to the mechanism underlying acute mountain sickness is discussed.

scholarly journals ANOXIA AND BRIGHTNESS DISCRIMINATION

1946 ◽  
Vol 29 (5) ◽  
pp. 335-351 ◽  
Author(s):  
Selig Hecht ◽  
Charles D. Hendley ◽  
Sylvia R. Frank ◽  
Charles Haig
Keyword(s):  
Sea Level ◽  
Conversion Factor ◽  
Brightness Discrimination ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Fourth Power ◽  
Receptor System ◽  
Quantitative Form ◽  
Light Intensities ◽  
Oxygen Concentrations

1. Brightness discrimination has been studied with individuals breathing oxygen concentrations corresponding to 7 altitudes between sea level and 17,000 feet. The brightnesses were 0.1, 0.01, and 0.001 millilambert involving only daylight (cone) vision. 2. At these light intensities, brightness discrimination begins to deteriorate at fairly low altitudes. The deterioration is obvious at 8,000 feet, and becomes marked at 15,000 feet, where at low brightness, the contrast must be increased 100 per cent over the sea level value before it can be recognized. 3. The impairment of brightness discrimination with increase in altitude is greater at higher altitudes than at lower. The impairment starts slowly and becomes increasingly rapid the higher the altitude. 4. Impairment of brightness discrimination varies inversely with the light intensity. It is most evident under the lowest light intensities studied, but shows in all of them. However, it decreases in such a way that the deterioration is negligible in full daylight and sunlight. 5. The thresholds of night (rod) vision and day (cone) vision are equally affected by anoxia. 6. The quantitative form of the relation between brightness discrimination ΔI/I and the prevailing brightness I remains the same at all oxygen concentrations. The curve merely shifts along the log I axis, and the extent of the shift indicates the visual deterioration. 7. The data are described in terms of retinal chemistry. Since anoxia causes only a shift in log I it is shown that the photochemical receptor system cannot be affected. Instead the conversion of photochemical change into visual function is impaired in such a way that the conversion factor varies as the fourth power of the arterial oxygen saturation.

New insights into ocular blood flow at very high altitudes

2009 ◽  
Vol 106 (2) ◽  
pp. 454-460 ◽  
Author(s):  
Martina M. Bosch ◽  
Tobias M. Merz ◽  
Daniel Barthelmes ◽  
Benno L. Petrig ◽  
Frederic Truffer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Altitude ◽  
Cerebral Edema ◽  
Arterial Oxygen Saturation ◽  
Acute Mountain Sickness ◽  
Fundus Photography ◽  
Arterial Oxygen ◽  
High Altitudes ◽  
Choroidal Blood Flow

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.

Operation Everest II: Arterial Oxygen Saturation and Sleep at Extreme Simulated Altitude

1992 ◽  
Vol 145 (4_pt_1) ◽  
pp. 817-826 ◽  
Author(s):  
James D. Anholm ◽  
A. C. Peter Powles ◽  
Ralph Downey ◽  
Charles S. Houston ◽  
John R. Sutton ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Simulated Altitude

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

2021 ◽  
Vol 6 (6) ◽  
Author(s):  
Alireza Kamali ◽  
Sepideh Sarkhosh ◽  
Hosein Kazemizadeh
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Saturation ◽  
Statistical Tests ◽  
Arterial Oxygen Saturation ◽  
Mean Blood Pressure ◽  
Arterial Oxygen ◽  
P Value ◽  
Double Blind ◽  
Significant Difference

Objectives: The aim of this study was to compare sedative effects of dexmedetomidine and fentanyl with midazolam and fentanyl in patients undergoing bronchoscopy. 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. 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. 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.

Sea-level PCO2 relates to ventilatory acclimatization at 4,300 m

1993 ◽  
Vol 75 (3) ◽  
pp. 1117-1122 ◽  
Author(s):  
J. T. Reeves ◽  
R. E. McCullough ◽  
L. G. Moore ◽  
A. Cymerman ◽  
J. V. Weil
Keyword(s):  
Sea Level ◽  
Ventilatory Response ◽  
Arterial Oxygen Saturation ◽  
Barometric Pressure ◽  
Interindividual Variation ◽  
Arterial Oxygen ◽  
Hypoxic Ventilatory Response ◽  
Wide Range ◽  
Time Required ◽  
End Tidal

There is considerable variation among individuals in the extent of, and the time required for, ventilatory acclimatization to altitude. Factors related to this variation are unclear. The present study tested whether interindividual variation in preascent ventilation or magnitude of hypoxic ventilatory response related to ventilatory acclimatization to altitude. Measurements in 37 healthy resting male subjects at sea level indicated a wide range (34–48 Torr) of end-tidal PCO2 values. When these subjects were taken to Pikes Peak, CO (4,300 m, barometric pressure 462 mmHg), the end-tidal PCO2 values measured on arrival and repeatedly over 19 days were correlated with the sea-level end-tidal PCO2. At 4,300 m, subjects with high end-tidal PCO2 had low values of arterial oxygen saturation (SaO2). Also, sea-level end-tidal PCO2 related to SaO2 after 19 days at 4,300 m. Twenty-six of the subjects had measurements of isocapnic hypoxic ventilatory response (HVR) at sea level. The end-tidal PCO2 values on arrival and after 19 days residence at 4,300 m were inversely related to the sea-level HVR values. Thus both the PCO2 and the HVR as measured at sea level related to the extent of subsequent ventilatory acclimatization (decrease in end-tidal PCO2) and the level of oxygenation at altitude. The finding in our cohort of subjects that sea-level end-tidal PCO2 was inversely related to HVR raised the possibility that among individuals the magnitude of the hypoxic drive to breathe influenced the amount of ventilation at all altitudes, including sea level.

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