Effects of occupied and unoccupied bed making on myocardial work in healthy subjects

Patients who have had serious heart attacks are often prescribed complete bed rest, and certain activities, such as making the bed, are performed while the patient remains in the bed. This is done to keep the patient's myocardial (heart muscle) work at a minimum. It is now questioned whether the increase in myocardial work required when a patient moves to a chair while the bed is made is significantly greater than the increase seen while the bed is made with the patient in it. Previous studies have found differences that were statistically significant, but not clinically important. This study examined myocardial work rate increases in healthy subjects when the bed was made with the patient in it and when it was made with the patient moving to a chair. Myocardial work rate was measured indirectly by measuring heart rate (HR), stroke volume (SV), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and total peripheral resistance (TPR). Results revealed that all measurements were relatively constant during bed making when the subjects remained in bed. When patients got out of bed, TPR steadily increased, with SBP, DBP, and MAP slightly decreasing. HR slightly increased and then decreased. The changes in cardiovascular variables were significantly different between the type of bed making. The variables quickly stabilized during rest periods. The important question is whether these changes indicate significantly increased myocardial work loads. Postural changes have been shown to cause these variables to change as a reflexive response to decreased venous return rather than increased myocardial work. The quick recovery seen in this study supports this notion. The results indicate that although unoccupied bed making does cause significant increases in cardiovascular variables, they are not necessarily indicative of clinically significant increases in myocardial work rates. Further studies using patients with illnesses are required. (Consumer Summary produced by Reliance Medical Information, Inc.)