Effect of different degrees of tilt on heart rate, pulse pressure and mean arterial blood pressure in young male and female Nigerians

ABSTRACT

It is well documented that changes in cardiac output are lower in the upright than supine positions. This study investigates the effect of different angles of tilt on the heart rate, pulse pressure and mean arterial pressure (MAP) of healthy male and female subjects in the 18 to 24 years age group and heights between 150 -180cm. All subjects were students in the University of Ilorin. Each participant was studied and the parameters were determined at the supine position and head up tilts at 15º, 30º, 45º and, 60º for 15 minutes interval. Additionally the supine position variables were taken as the resting value against each of the head up tilt angle degree. The result shows that there was progressive and significant increase in heart rate from supine 59.5±1.3beat/min to 62.2 ± 1.4beat/min (p<0.05) at 15º; 59.5±1.3beat/min to 63.8 ± 1.4beat/min at 30⁰ tilt (p<0.05); 59.5 ± 1.3beat/min to 65.9 ± 1.4beat/min at 45⁰ tilt (p<0.05); 59.5 ± 1.3beat/min and 68.2 ± 1.6beat/min at 60⁰ tilt (p<0.05). The results also showed that there were significant (p<0.05) increases in pulse pressure at all angles which peaked at 30⁰ tilt. Furthermore, it was observed that MAP significantly (p<0.05) increased with corresponding increase in the angle of tilt from supine to 60º (76.5±2.2 mmHg (supine) to 80.6±2.1 mmHg (15 º) to 83.8±2.1 mmHg (30 º) to 85.4±2.1 mmHg (45 º) to 85.4±2.2 mmHg (60 º). Our results demonstrated that the heart rate, pulse pressure and MAP were significantly (p<0.05) increased in males and females for all the variables.