Impact of mental and physical stress on blood pressure and pulse pressure under normobaric versus hypoxic conditions.

Michael Trapp,Josef W Egger,Peter Komericki,Giuseppe Schillaci,Peter M Rohrer,Mila Cervar-Zivkovic,Eva-Maria Trapp,Rosemarie Velik,Wolfgang Domej,Nina Hörlesberger,Johannes Baulmann,Dieter Magometschnigg,Alexander Avian,Christopher Torrens

doi:10.1371/journal.pone.0089005

Abstract

ObjectiveHypobaric hypoxia, physical and psychosocial stress may influence key cardiovascular parameters including blood pressure (BP) and pulse pressure (PP). We investigated the effects of mild hypobaric hypoxia exposure on BP and PP reactivity to mental and physical stress and to passive elevation by cable car.Methods36 healthy volunteers participated in a defined test procedure consisting of a period of rest 1, mental stress task (KLT-R), period of rest 2, combined mental (KLT-R) and physical task (bicycle ergometry) and a last period of rest both at Graz, Austria (353 m asl) and at the top station Dachstein (2700 m asl). Beat-to-beat heart rate and BP were analysed both during the test procedures at Graz and at Dachstein and during passive 1000 m elevation by cable car (from 1702 m to 2700 m).ResultsA significant interaction of kind of stress (mental vs. combined mental and physical) and study location (Graz vs. Dachstein) was found in the systolic BP (p = .007) and PP (p = .002) changes indicating that during the combined mental and physical stress task sBP was significantly higher under hypoxic conditions whereas sBP and PP were similar during mental stress both under normobaric normoxia (Graz) and under hypobaric hypoxia (Dachstein). During the passive ascent in cable car less trivialization (psychological coping strategy) was associated with an increase in PP (p = .004).ConclusionOur data show that combined mental and physical stress causes a significant higher raise in sBP and PP under hypoxic conditions whereas isolated mental stress did not affect sBP and PP under hypoxic conditions. PP-reaction to ascent in healthy subjects is not uniform. BP reactions to ascent that represents an accumulation of physical (mild hypobaric hypoxia) and psychological stressors depend on predetermined psychological traits (stress coping strategies). Thus divergent cardiovascular reactions can be explained by applying the multidimensional aspects of the biopsychosocial concept.

Highlights

Hypertension is the most important modifiable risk factor for cardiovascular morbidity and mortality worldwide [1]
A significant interaction between kind of stress and study location was found in the changes of systolic blood pressure (sBP) (p = .007) and pulse pressure (PP) (p = .002)
While the sBP and PP reaction to mental stress was slightly higher in Graz as compared to Dachstein, the sBP and PP reaction to combined mental and physical stress was significantly lower in Graz as compared to Dachstein

Summary

Introduction

Hypertension is the most important modifiable risk factor for cardiovascular morbidity and mortality worldwide [1]. The pulsatile component of arterial blood pressure (BP), i.e. pulse pressure (PP), has been recognized as an important predictor of future cardiovascular events [2,3,4], and its predictive power is stronger than that of diastolic blood pressure (dBP) [5]. PP is a complex parameter which is determined by ventricular ejection and by arterial stiffness/pulse wave reflection [6], and is associated with aging and increased large-artery pulse wave velocity (PWV) [7,8]. Recent studies have shown that acute hypobaric hypoxia provokes an increase in resting HR and BP during real altitude exposure or simulated altitude exposure in a hypobaric chamber [13]

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Discussion

Conclusion