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Ambulatory IV Diuretic Therapy for Decompensated Heart Failure
Study Questions:
What is the safety and efficacy of intravenous (IV) diuretic administration in ambulatory heart failure (HF)?
Methods:
The study cohort was comprised of patients with early HF decompensation who presented to an ambulatory treatment clinic that allowed IV infusion and was staffed by a pharmacist and a nurse and supervised by a nurse practitioner. These included hemodynamically stable ambulatory patients with chronic systolic or diastolic HF and signs and symptoms of worsening congestion. Patients referred to the emergency department or inpatient ward for further evaluation were excluded from the analysis. Patients are typically scheduled for same-day or next-day treatment depending on the time of presentation to the ambulatory cardiology clinics and are rebooked for repeat visits as needed. Patients were assigned to one of four protocol groups (Low Dose, Standard Dose, High Dose, and Mega Dose) based on their total daily dose of home oral diuretic (maintenance dose). All doses were expressed in mg of oral furosemide and torsemide, or bumetanide doses were converted to an equivalent furosemide dose using standard conversion guidelines.
The efficacy outcomes included urine output and weight loss. The evaluated safety outcomes included hypokalemia, worsening renal function (WRF), and ototoxicity within 7 days of the infusion. Outcomes were compared across maintenance diuretic dose groups with the Kruskal-Wallis test. They calculated the relative risk for hospitalization by comparing observed rates of 30-day hospitalization to the clinician-predicted rates.
Results:
Sixty patients who underwent 112 discrete treatment visits were included in their final analysis. The median age was 70 years (interquartile range [IQR], 60-80 years). Patients were predominantly male (56.7%) and Caucasian (75%); 40% of patients had diastolic HF.
The median urine output was 1045 ml (IQR, 619-1400 ml). The median clinic weight loss was 1 kg (IQR, 0.6-1.3 kg). The median home weight loss was 1.1 kg (IQR, 0.2-1.9 kg). Both the Standard Dose and the High Dose groups had more urine output during the 3-hour clinic visit than the Mega Dose group (1402 ml [IQR, 1003-1795] vs. 1150 ml [IQR, 1040-1398] vs. 950 ml [IQR, 500-1180], respectively; p < 0.05 for both comparisons with the Standard Dose group). Clinic weight loss was greater in the Standard Dose group compared to the Mega Dose group (1.3 kg [IQR, 0.9- 1.8] vs. 0.9 kg [IQR, 0.4-1.2]; p < 0.05). There were no statistically significant differences across diuretic dosing subgroups with respect to home weight loss (p = 0.37).
At 30-day follow up, there were 31.7% total hospitalizations (n = 19), including 18.3% (n = 11) for worsening HF, and no deaths. At 60-day follow up, rates of all-cause hospitalization and HF hospitalization were 38.3% and 21.7% with one recorded death. The study authors compared these findings to hospitalization and was reported by the referring clinician to be imminent or expected within 30 days of referral for 52.8% of patients (relative risk for all-cause hospitalization for observed vs. predicted, 0.60; 95% confidence interval, 0.38-0.94; p = 0.03). There were 9.4% (n = 3) HF hospitalizations at 30 days and 59.4% (n = 5) HF hospitalizations at 60 days in patients with urine output greater than the median. Among patients with urine output less than the median, 18.2% (n = 6) of patients at 30 days and 24.2% (n = 8) of patients at 60 days were hospitalized for HF.
Severe WRF did not occur after any clinic visits. Mild WRF occurred after 8.9% of visits (n = 10), including six in patients with a history of renal impairment. Serum creatinine returned to baseline for each patient within a median of 4 days (IQR, 3-6 days) after initial laboratory follow-up. Mild and severe hypokalemia occurred after 2.7% (n = 3) and 0.9% (n = 1) of clinic visits, respectively. No clinically significant arrhythmias were noted on telemetry during any of clinic visits.
Conclusions:
The authors concluded that ambulatory loop diuretic administration using a standardized protocol is effective in achieving decongestion in patients with decompensated HF across the spectrum of ejection fraction and maintenance diuretic doses.
Perspective:
This is an important study because it provides one more ‘blueprint’ for reducing HF hospitalizations. Other options to reduce HF hospitalizations include providing IV diuresis at home by nurse practitioner, implantable hemodynamic monitoring such as St. Jude’s CardioMEMS, and outpatient ultrafiltration.
Keywords: Ambulatory Care, Bumetanide, Diuretics, Emergency Service, Hospital, Furosemide, Heart Failure, Hemodynamics, Hypokalemia, Nurse Practitioners, Pharmacists, Risk, Sodium Chloride Symporter Inhibitors, Sulfonamides, Telemetry, Ultrafiltration, Weight Loss
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