The influence of fluid and diuretic administration on the index of atrial contribution in sequentially paced patients.

AIMS

To examine whether acute changes in patient hydration can change atrial contribution (AC) to circulatory function.

METHODS AND RESULTS

Atrial contribution was quantified by beat-to-beat changes in the amplitude of pulse oximetry signal in 24 paced outpatients. Changes in body weight were used for assessment of changes in total body water. The first measurement was performed at steady state. The second measurement was made after infusion of saline (5 mL/kg) and the third measurement was obtained 2 h after a bolus of furosemide (1 mg/kg). Changes found after furosemide administration (compared with steady state): a substantial decrease in body weight from median 78.6 (interquartile range 65.7-86.5) to 77.1 (64.4-85.6) kg (P < 0.001), accompanied by an increase in AC from 30.4 (20.2-47.1) up to 43.3 (30.6-80.9)% (P < 0.001). An increase in heart rate and shortening of the atrioventricular conduction time occurred during acute hypohydration in some of the subjects.

CONCLUSION

Administration of furosemide was followed by a decrease in body weight and an increase in AC to stroke volume. This suggests that in conditions where pre-load is reduced cardiac output is preserved by an increase in AC enforced by sympathetic activation.