INTERMITTENT VERSUS CONTINUOUS HYPOXIA: IMPACT ON HEMODYNAMIC VARIABLES AND GENE EXPRESSION

The physiologic response to hypoxia may be determined by variables such as exposure pattern and inducible nitric oxide synthase (iNOS) expression. Blood pressure (BP) and heart rate (HR) responses to daily exposure (X 3 days) of intermittent hypoxia (IH) vs. continuous hypoxia (CH) (equivalent total exposure time) were compared. The relation between BP and HR responses and iNOS expression under IH and CH conditions was also examined. On 3 consecutive days, 10 normal males had six 10-min. hypoxic exposures (oxyhemoglobin saturation, SpO2: 80-90%), with each exposure separated by 10 min. of normoxia. Subjects also had 3 consecutive days of CH (60 min/day; SpO2: 80-90%). IH and CH exposure blocks were separated by a greater than 7 days. BP, HR, and SpO2 were recorded during the 5 min. prior to and the last 5 min. of each daily IH and CH exposure. Venous blood for iNOS mRNA was obtained before exposure on day 1, and 2 hrs. after the last exposure on day 3. HR, systolic and diastolic BP were significantly (p less than 0.05) increased from baseline- to end-exposure on each day, regardless of IH or CH. There was a significant negative correlation (p less than 0.01) between both diastolic and mean BP with iNOS at the end of the day 3 IH session. Hypoxic stress reflected by IH and CH is associated with significant, but comparable changes in BP. Negative correlation between BP and iNOS mRNA in conjunction with IH, but not CH, exposure suggests that the hemodynamic response to IH may be modulated by iNOS

Tales from the Hypoxic Side High Altitude Scientific Adventures in the Himalaya

Lecture presentations hosted by the College of Nursing featuring faculty, graduate students, nursing professionals, and allied health experts. Each lunchtime lecture is devoted to a timely topic examining the training, research and scholarly needs of the nursing community.Lectures; Himalaya

Heights and haematology: the story of haemoglobin at altitude

In order to compensate for the low partial pressure of oxygen at altitude, the human body undergoes a number of physiological changes. A vital component in this process is the increase in the concentration of circulating haemoglobin. The role of HIF‐1α, erythropoietin and red blood cells in this acclimatisation process is described, together with the fall in plasma volume that increases the concentration of haemoglobin in the early stages of hypoxic exposure

A review of the literature on the accuracy, strengths, and limitations of visual, thoracic impedance, and electrocardiographic methods used to measure respiratory rate in hospitalized patients.

BackgroundRespiratory rate (RR) is one of the most important indicators of a patient's health. In critically ill patients, unrecognized changes in RR are associated with poorer outcomes. Visual assessment (VA), impedance pneumography (IP), and electrocardiographic-derived respiration (EDR) are the three most commonly used methods to assess RR. While VA and IP are widely used in hospitals, the EDR method has not been validated for use in hospitalized patients. Additionally, little is known about their accuracy compared with one another. The purpose of this systematic review was to compare the accuracy, strengths, and limitations of VA of RR to two methods that use physiologic data, namely IP and EDR.MethodsA systematic review of the literature was undertaken using prespecified inclusion and exclusion criteria. Each of the studies was evaluated using standardized criteria.ResultsFull manuscripts for 23 studies were reviewed, and four studies were included in this review. Three studies compared VA to IP and one study compared VA to EDR. In terms of accuracy, when Bland-Altman analyses were performed, the upper and lower levels of agreement were extremely poor for both the VA and IP and VA and EDR comparisons.ConclusionGiven the paucity of research and the fact that no studies have compared all three methods, no definitive conclusions can be drawn about the accuracy of these three methods. The clinical importance of accurate assessment of RR warrants new research with rigorous designs to determine the accuracy, and clinically meaningful levels of agreement of these methods

A review of the literature on the accuracy, strengths, and limitations of visual, thoracic impedance, and electrocardiographic methods used to measure respiratory rate in hospitalized patients.

BackgroundRespiratory rate (RR) is one of the most important indicators of a patient's health. In critically ill patients, unrecognized changes in RR are associated with poorer outcomes. Visual assessment (VA), impedance pneumography (IP), and electrocardiographic-derived respiration (EDR) are the three most commonly used methods to assess RR. While VA and IP are widely used in hospitals, the EDR method has not been validated for use in hospitalized patients. Additionally, little is known about their accuracy compared with one another. The purpose of this systematic review was to compare the accuracy, strengths, and limitations of VA of RR to two methods that use physiologic data, namely IP and EDR.MethodsA systematic review of the literature was undertaken using prespecified inclusion and exclusion criteria. Each of the studies was evaluated using standardized criteria.ResultsFull manuscripts for 23 studies were reviewed, and four studies were included in this review. Three studies compared VA to IP and one study compared VA to EDR. In terms of accuracy, when Bland-Altman analyses were performed, the upper and lower levels of agreement were extremely poor for both the VA and IP and VA and EDR comparisons.ConclusionGiven the paucity of research and the fact that no studies have compared all three methods, no definitive conclusions can be drawn about the accuracy of these three methods. The clinical importance of accurate assessment of RR warrants new research with rigorous designs to determine the accuracy, and clinically meaningful levels of agreement of these methods