A patient develops increasing dyspnea and hypoxemia 2 days after heart surgery. What procedure should the nurse anticipate assisting with to determine whether the patient has acute respiratory distress syndrome (ARDS) or pulmonary edema caused by heart failure?

C. Mean arterial pressure (MAP) reflects the average pressure in the arteries during one cardiac cycle and is an important indicator of tissue perfusion. A MAP of 56 mm Hg is below the normal range (typically >60 mm Hg) and may indicate inadequate tissue perfusion. While norepinephrine is commonly used to increase blood pressure and improve tissue perfusion in hypotensive patients, a MAP of 56 mm Hg suggests that the current infusion rate may not be sufficient to maintain adequate perfusion, and adjusting the infusion rate may be warranted.

A. Norepinephrine is a vasopressor medication primarily used to increase blood pressure in patients with hypotension or shock. A low pulmonary artery wedge pressure (PAWP) suggests decreased preload, which may indicate hypovolemia or inadequate fluid resuscitation. In this case, adjusting the norepinephrine infusion rate may not be necessary, but rather addressing the underlying cause of hypovolemia or inadequate preload.

B. Systemic vascular resistance (SVR) represents the resistance the heart must overcome to pump blood into the systemic circulation. An elevated SVR may suggest vasoconstriction, which could be a desired effect of norepinephrine infusion to increase blood pressure. Therefore, an elevated SVR may not necessarily indicate a need to adjust the norepinephrine infusion rate, as it may reflect the medication's intended action.

D. Norepinephrine primarily acts on alpha-adrenergic receptors to increase blood pressure by inducing vasoconstriction. While it may cause reflex bradycardia due to increased systemic vascular resistance, a heart rate of 58 beats/min may be within an acceptable range depending on the patient's clinical condition and baseline heart rate. Therefore, a slow heart rate alone may not necessarily indicate a need to adjust the norepinephrine infusion rate unless it is associated with signs of inadequate tissue perfusion or other concerning symptoms.

B. Muffled heart sounds, often described as distant or indistinct, are classic findings in cardiac tamponade. The accumulation of fluid in the pericardial sac dampens the transmission of sound from the heart to the chest wall, resulting in muffled heart sounds on auscultation. This finding is known as Beck's triad, which also includes hypotension and jugular venous distention.

A. Bradycardia is not a typical finding in cardiac tamponade. In fact, tachycardia is more commonly observed due to the compensatory response to decreased cardiac output and decreased stroke volume. The sympathetic nervous system is activated, leading to an increase in heart rate as a compensatory mechanism to maintain cardiac output.

C. Flattened neck veins are not consistent with cardiac tamponade. In cardiac tamponade, jugular venous distention (JVD) is typically observed due to increased venous pressure resulting from impaired right ventricular filling. The presence of JVD is an important clinical finding in cardiac tamponade and can help differentiate it from other causes of shock.

D. Sudden lethargy can occur in various medical emergencies, including cardiac tamponade, but it is not a specific or diagnostic finding for this condition. In cardiac tamponade, symptoms may include dyspnea, chest pain, hypotension, and signs of decreased cardiac output such as cool extremities and altered mental status. However, sudden lethargy alone may not be specific enough to confirm cardiac tamponade.