Addition of a Thiazide: An Effective Remedy for Furosemide Resistance After Cardiac Operations

Background. The frequent use of diuretic drugs in cardiac surgical practice contrasts with the lack of documentation regarding diuretic treatment in this setting. The aims of this study were to delineate the need for diuretic drugs in adult cardiac surgical practice and to evaluate the impact of adding a combination of 50 mg hydrochlorothiazide and 5 mg amiloride orally to patients responding poorly to furosemide. Methods. Two hundred ten consecutive patients, 159 undergoing coronary artery bypass grafting procedures and 51 having valve operations, were studied. Results. Seventy-seven patients received large doses of furosemide (≥80 mg/24 h) at some time during the postoperative course, and of these 20 responded poorly to furosemide (weight loss 0.3 ± 0.2 kg) despite considerable fluid retention. The addition of hydrochlorothiazide and amiloride provided a prompt and effective remedy to relative furosemide resistance. Average weight loss was 2.3 ± 0.2 kg (p < 0.01 compared with response to furosemide) and average diuresis was 2,949 ± 156 mL in the following 24 hours. Conclusions. Relative furosemide resistance is common after cardiac operations. Thiazides, although they are mild diuretic agents, may serve as useful adjuncts in this setting.