Skip to main content

HF diuretic resistance....the causes and management


Diuretic resistance is multifactorial.
  • Patients with heart failure often have some degree of chronic kidney disease.  As previously discussed, loop diuretics reached the tubular lumen by active secretion.  In renal insufficiency, secretion of loop diuretics is reduced.  This is in part because of accumulated, endogenous organic anions, which compete with loop diuretics at the transporter site.  Increased doses of loop diuretics are thus required to overcome this competitive inhibition.  Additionally, renal blood flow may be decreased in states of renal impairment, further interfering with diuretic secretion. Peak urinary concentrations of loop diuretics are reduced and delayed, resulting in a diminished diuretic effect.
  • Non-adherence to sodium restriction can obviate the benefits of loop diuretics.
  • Non-steroidal anti-inflammatory drugs interfere with prostaglandin synthesis and can antagonize the response to loop diuretics.

Resistance management 
Considering the mechanisms of diuretic resistance discussed above, there are 4 strategies to manage diuretic resistance:
  • Ensure adherence to sodium restriction and medical regimen.
  • Escalate the dose of the loop diuretic.  Alternatively, some clinicians favor changing to a different loop diuretic.  For example, bumetanide has better oral bioavailability than furosemide (80% versus 40%, respectively).  Although bumetanide is more potent than furosemide by a factor of 40 based on weight, both drugs should be equally effective in equivalent dosing.
  • Consider changing intravenous bolus injections to continuous infusion of a loop diuretic.  Continuous intravenous infusion has the advantage of maintaining an effective urinary drug concentration and avoiding periods of post-diuresis sodium retention.  An IV drip may be considered if patients with CHF are refractory to 250 mg of furosemide given orally or intravenously (e.g. continuous furosemide infusion of 10 to 20 mg/hr or bumetanide infusion of 0.5 mg/hr).
  • Consider combination diuretic therapy.  At least 3 studies support the use of thiazide diuretics in addition to loop diuretics for patients resistant to high doses of loop diuretics.  Although there was survival benefit to spironolactone in the RALES study, this was not specifically tested in the context of diuretic resistance and CHF.

Comments

Post a Comment

Popular posts from this blog

Driving Pressure in ARDS: A new concept!

Driving Pressure and Survival in the Acute Respiratory Distress Syndrome Marcelo B.P. Amato, M.D., Maureen O. Meade, M.D., Arthur S. Slutsky, M.D., Laurent Brochard, M.D., Eduardo L.V. Costa, M.D., David A. Schoenfeld, Ph.D., Thomas E. Stewart, M.D., Matthias Briel, M.D., Daniel Talmor, M.D., M.P.H., Alain Mercat, M.D., Jean-Christophe M. Richard, M.D., Carlos R.R. Carvalho, M.D., and Roy G. Brower, M.D. N Engl J Med 2015; 372:747-755 February 19, 2015 DOI: 10.1056/NEJMsa1410639 BACKGROUND Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (V T ), and higher positive end-expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory-system compliance (C RS ) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size)...
5 comments
Read more

Anaphylaxis updates part 2- Empty Ventricle Syndrome

Patients with anaphylaxis should not suddenly sit, stand, or be placed in the upright position. Instead, they should be placed on the back with their lower extremities elevated or, if they are experiencing respiratory distress or vomiting, they should be placed in a position of comfort with their lower extremities elevated. This accomplishes 2 therapeutic goals: 1) preservation of fluid in the circulation (the central vascular compartment), an important step in managing distributive shock; and 2) prevention of the empty vena cava/empty ventricle syndrome, which can occur within seconds when patients with anaphylaxis suddenly assume or are placed in an upright position. Patients with this syndrome are at high risk for sudden death. They are unlikely to respond to epinephrine regardless of route of administration, because it does not reach the heart and therefore cannot be circulated throughout the body
Post a Comment
Read more

Epidural catheter tests...not only the test dose

Siphon test The catheter is held upright and a fluid level sought. If the catheter is then elevated, the fluid level should fall (see inset) as the fluid siphons in to the epidural space, which is usually under negative pressure compared with atmospheric. If the fluid column continues to rise, this may suggest subarachnoid placement. The siphon test can be reassuring, but is not mandatory. Aspiration  This should be considered mandatory. The Luer connector is attached to the catheter and a syringe is used to apply negative pressure. Free and continued aspiration of clear fluid can indicate subarachnoid placement of the catheter. However, if saline has been used for loss of resistance, it is not unusual for a small amount of this to be aspirated. If there is doubt, the aspirated fluid can be tested for glucose (cerebrospinal fluid will generally test positive) or mixed with thiopentone (cerebrospinal fluid forms a precipitate). If blood is freely and continuously aspirated, this sug...
Post a Comment
Read more