Why would a person be encouraged to drink more orally to manage hypotension and simultaneously be administered Furosemide (Lasix) post-operative cardiac surgery due to edema and fluid retention?

From the Guidelines

After cardiac surgery, a patient may be encouraged to drink more fluids orally to increase blood pressure while simultaneously receiving Lasix (furosemide) to manage edema because these interventions target different physiological issues, as supported by the most recent evidence from the Perioperative Quality Initiative consensus recommendations 1.

Rationale for Intervention

Oral fluid intake helps maintain adequate blood volume and pressure, particularly if the patient is experiencing relative hypovolemia in the circulating blood compartment. Meanwhile, Lasix addresses the problem of fluid retention and edema in the tissues, which often occurs after cardiac surgery due to inflammatory responses and altered cardiac function.

Key Considerations

• The goal is to achieve a balanced fluid status - maintaining adequate circulating volume for blood pressure support while preventing excessive fluid accumulation in tissues.
• This approach recognizes that fluid distribution between compartments (vascular versus interstitial) is often imbalanced post-surgery, requiring seemingly contradictory interventions.
• Careful monitoring of vital signs, urine output, and electrolytes is essential during this process to ensure proper fluid management and prevent complications like electrolyte imbalances or kidney injury, as emphasized by guidelines for perioperative care 1.

Management Strategy

• Typically, Lasix might be administered at 20-40mg intravenously or orally, depending on the severity of edema.
• The decision to use diuretics like Lasix should consider the patient's volume status and the risk of post-operative heart failure, as discussed in guidelines for pre-operative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery 1.
• Recent consensus recommendations from the international multidisciplinary perioperative quality initiative provide a framework for evidence-based fluid management in the perioperative period, including the use of diuretics and fluid therapy 1.

From the FDA Drug Label

As with any effective diuretic, electrolyte depletion may occur during furosemide therapy, especially in patients receiving higher doses and a restricted salt intake Hypokalemia may develop with furosemide, especially with brisk diuresis, inadequate oral electrolyte intake, when cirrhosis is present, or during concomitant use of corticosteroids, ACTH, licorice in large amounts, or prolonged use of laxatives. Patients receiving furosemide should be advised that they may experience symptoms from excessive fluid and/or electrolyte losses

The person may be encouraged to drink more orally to bring BP up and at the same time be given Lasix post-op cardiac surgery due to edema/fluid retention because:

• Furosemide (Lasix) can cause excessive diuresis, leading to dehydration and electrolyte imbalance.
• Drinking more orally can help replace lost fluids and electrolytes, reducing the risk of hypotension and electrolyte depletion.
• The goal is to balance the need to reduce edema with the risk of dehydration and electrolyte imbalance 2.

From the Research

Post-Operative Care for Cardiac Surgery Patients

• The management of post-operative care for cardiac surgery patients is complex and requires a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass 3.
• Patients undergoing cardiac surgery are at high risk for post-operative complications, including fluid retention and edema, which can lead to hypotension 4, 5, 6, 7.

Hypotension Management

• Hypotension is a common problem in post-operative cardiac surgery patients and can be caused by systemic vasodilatation and relative hypovolemia 6.
• Prolonged episodes of perioperative hypotension have been linked to post-operative outcome, including the incidence of myocardial adverse events 6.
• Intraoperative hypotension is associated with an increased risk of stroke and renal replacement therapy in patients undergoing cardiac surgery 5, 7.

Fluid Management

• Adequate fluid resuscitation is a key component of post-operative care for cardiac surgery patients 3.
• Patients may be encouraged to drink more orally to bring blood pressure up, while also being given diuretics like Lasix to manage fluid retention and edema 4.
• The use of diuretics like Lasix may seem counterintuitive, but it is aimed at reducing fluid overload and preventing further complications, while oral fluid intake is aimed at maintaining adequate blood pressure 3.

Medication Management

• Medications like Lasix are commonly used in post-operative care for cardiac surgery patients to manage fluid retention and edema 4.
• The use of vasoactive and inotropic drugs, as well as volatile anesthesia and mechanical ventilation, should be tailored to individual patient needs and targeted to maintain optimal hemodynamic parameters 4, 3.