Hemodynamic Monitoring Case Study

Advanced Medical-Surgical Nursing (University of Rhode Island)

Patient Overview:Mrs. M., a 61-year-old female, is admitted to the critical care unit following emergency surgery for a perforated bowel. During surgery, she experienced an estimated blood loss of 300 mL and received 2.5 L of crystalloid solution. She has an arterial line, a subclavian triple-lumen catheter, and an indwelling urinary catheter. Upon admission, Mrs. M. is intubated, sedated, and placed on mechanical ventilation with the following settings: assist/control mode at 12 breaths/min, tidal volume 650 mL, fraction of inspired oxygen 1.0 (100%), and positive end-expiratory pressure 5 cm H2O.

Initial Postoperative Vital Signs and Laboratory Findings:

• Heart rate: 140 beats/min
• Blood pressure: 88/49 mm Hg
• Mean arterial pressure: 62 mm Hg
• Respiratory rate: 12 breaths/min
• Right atrial pressure: 4 mm Hg
• Temperature: 39.2°C (102.6°F)
• Lactate: 1.1 mEq/L

Interventions:The physician orders a 500-mL infusion of normal saline (NS) 0.9%, a repeat serum lactate level, and the replacement of the triple-lumen catheter with a catheter that measures ScvO2. The nurse administers the fluids and assists with the placement of the ScvO2 catheter.

Reassessment Findings:

• Heart rate: 118 beats/min
• Blood pressure: 96/52 mm Hg
• Mean arterial pressure: 66 mm Hg
• Right atrial pressure: 8 mm Hg
• Cardiac index (CI): 2.8 L/min/m²
• ScvO2: 59%
• Lactate: 3.6 mEq/L

Discussion:

1. Rationale for Placing the ScvO2 Catheter:ScvO2 monitoring is crucial for critically ill or injured patients who may develop an imbalance between oxygen delivery and consumption. It is particularly beneficial for patients with trauma, acute respiratory distress syndrome, sepsis, and those undergoing complex cardiac surgery. In Mrs. M.’s case, ScvO2 monitoring helps assess her oxygenation status and guide therapy.
2. Normal Range for ScvO2:The normal range for ScvO2 is 65% to 85%.
3. Possible Causes of Decreased ScvO2 in Mrs. M.:A decreased ScvO2 (<65%) can result from several factors. For Mrs. M., an elevated metabolic rate due to fever (102.6°F) is a likely cause. Additionally, inadequate oxygen perfusion to tissues, possibly due to her recent surgery and resultant physiological stress, could contribute to her low ScvO2 levels.
4. Clinical Significance of Increased Lactate Levels:The increase in lactate levels from 1.1 mEq/L to 3.6 mEq/L is clinically significant. Elevated lactate levels indicate anaerobic metabolism, often due to inadequate oxygen delivery to tissues. Conditions such as heart failure, severe infection, or shock can lead to elevated lactate levels. In Mrs. M.’s case, the increased lactate may suggest sepsis, indicated by her high heart rate, low blood pressure, and fever. This rise in lactate levels could reflect insufficient oxygenation and blood flow throughout her body.

Conclusion:Mrs. M.’s case illustrates the importance of hemodynamic monitoring in critically ill patients. Continuous assessment of vital signs and laboratory parameters, including ScvO2 and lactate levels, is essential in guiding appropriate therapeutic interventions and improving patient outcomes in the critical care setting.