A 43-year-old man comes to the emergency department after experiencing 4 episodes of coffee ground emesis that started earlier this morning. He also describes epigastric pain over the last 3-4 months that was relieved by over-the-counter antacids. He has no other past medical history. The patient has smoked a pack of cigarettes daily for the last 20 years but does not use alcohol or illicit drugs. Blood pressure is 70/40 mm Hg and pulse is 130/min and regular. Extremities are cool to the touch with loss of skin turgor. Intravenous access is obtained via 2 large-bore peripheral catheters, and rapid infusion of 2 liters of normal saline is initiated. This intervention is most likely to increase which of the following hemodynamic parameters?

Question

A 43-year-old man comes to the emergency department after experiencing 4 episodes of coffee ground emesis that started earlier this morning.  He also describes epigastric pain over the last 3-4 months that was relieved by over-the-counter antacids.  He has no other past medical history.  The patient has smoked a pack of cigarettes daily for the last 20 years but does not use alcohol or illicit drugs.  Blood pressure is 70/40 mm Hg and pulse is 130/min and regular.  Extremities are cool to the touch with loss of skin turgor.  Intravenous access is obtained via 2 large-bore peripheral catheters, and rapid infusion of 2 liters of normal saline is initiated.  This intervention is most likely to increase which of the following hemodynamic parameters?

Quizplus · Accepted Answer

This patient's hypotension, tachycardia, and cool extremities are indicative of hypovolemic shock most likely due to upper gastrointestinal bleeding from peptic ulcer disease (coffee ground emesis due to oxidation of heme iron by exposure to gastric acid). Decreased intravascular volume from significant blood loss activates the sympathetic nervous system and renin-angiotensin-aldosterone system (RAAS), which help to maintain systemic blood pressure via the following compensatory mechanisms: In the treatment of hypovolemic shock, the most important intervention other than identifying and eliminating the source of bleeding is rapid infusion of blood products and crystalloid solutions such as normal saline. By infusing intravenous fluids, intravascular volume and ventricular preload can be increased rapidly. The increase in preload stretches the myocardium and increases the end-diastolic sarcomere length, leading to an increase in stroke volume and cardiac output by the Frank-Starling mechanism. (Choice A) Aortic wall elasticity is based on the intrinsic structure of the aortic media and is not affected by fluid infusions. (Choice B) The diastolic ventricular compliance is determined by intrinsic properties of the myocardium and is unaffected by crystalloid infusions. Conditions that decrease ventricular compliance include left ventricular hypertrophy (aortic stenosis, hypertension), hypertrophic cardiomyopathy, and infiltrative disorders (amyloidosis, sarcoidosis). (Choice D) Adequate fluid resuscitation in a hypovolemic patient decreases the sympathetic drive and endogenous catecholamine release, resulting in decreased heart rate. (Choice E) Plasma renin activity increases in patients with hypovolemic shock due to activation of RAAS and would be expected to decrease after intravenous fluid resuscitation. (Choices F and G) In a patient with hypovolemic shock, total peripheral resistance and myocardial contraction velocity are high due to sympathetic activation. Administration of fluids will reduce sympathetic activation and decrease both of these parameters. Educational objective: Intravenous fluids increase the intravascular and left ventricular end-diastolic volumes. The increase in preload stretches the myocardium and increases the end-diastolic sarcomere length, leading to an increase in stroke volume and cardiac output by the Frank-Starling mechanism.

A 43-Year-Old Man Comes to the Emergency Department After Experiencing