Thursday, March 18, 2021

Pulmonary Hypertension Case File

Posted By: Medical Group - 3/18/2021 Post Author : Medical Group Post Date : Thursday, March 18, 2021 Post Time : 3/18/2021
Pulmonary Hypertension Case File
Lydia Conlay, MD, PhD, MBA, Julia Pollock, MD, Mary Ann Vann, MD, Sheela Pai, MD, Eugene C. Toy, MD

Case 20
A 44-year-old woman is scheduled for a vaginal hysterectomy for dysmenorrhea that has failed medical therapy. Although she had been otherwise healthy, over the past year, she has increasingly noticed exertional dyspnea, particularly when shopping in large stores. These symptoms have worsened, to the point that she sometimes felt as though she was about to “pass out.” She consulted her primary physician several months ago. After an extensive workup, she was diagnosed with idiopathic pulmonary hypertension, and treated with amlodipine, a calcium channel blocker, and furosemide. The administration of another medication by permanent central indwelling catheter has been discussed, but is not warranted at this time.

The patient’s vital signs on presentation include a blood pressure 102/56 mm Hg, heart rate 90 bpm, 94% O2 saturation. On physical examination, she has clear lungs to auscultation, mild ankle edema, a 2/6 systolic murmur, and an S4 gallop. The ECG shows right axis deviation and right ventricular hypertrophy. An echocardiogram demonstrates mild right ventricular (RV) enlargement, and a right ventricular systolic pressure (RVSP) of 35 mm Hg. Following the induction of anesthesia, her oxygen saturation decreases to 90%, blood pressure falls to 80/43 mm Hg, and her heart rate increases to 110 bpm.

➤ What should the preoperative evaluation include?

➤ What is the impact of the anesthesia and surgical procedure on pulmonary hypertension?

➤ What are the goals of anesthetic management?


ANSWERS TO CASE 20:
Pulmonary Hypertension

Summary: A 44-year-old woman with pulmonary hypertension and right heart failure presents for a vaginal hysterectomy under general anesthesia.

Preoperative evaluation: The evaluation of patients with pulmonary hypertension should focus on identifying the severity of the disease, the patient’s baseline cardiac function, and assure that the patient’s condition is optimized prior to surgery. It typically includes an arterial blood gas, a chest radiograph, ECG, echocardiography, and right heart catheterization.

Effect of anesthetic and surgical techniques on pulmonary hypertension: Anesthesia and surgery can dramatically affect artery (PA) pressure and right heart function. Acidemia, hypoxia, hypercarbia, and hypotension in the perioperative period can worsen both pulmonary hypertension and right ventricular failure.

Goals of anesthetic management: Goals are directed toward maintaining the stability of pulmonary and systemic arterial pressure, the maintenance of normal sinus rhythm, and the appropriate volume status, oxygenation, and ventilation.


ANALYSIS

Objectives
1. Understand the pathophysiology of pulmonary hypertension.
2. Be able to conduct a preoperative evaluation in a patient with pulmonary hypertension.
3. Understand the implications of anesthesia in the setting of pulmonary hypertension, and develop anesthetic management plan accordingly.
4. Manage the perioperative complications in a patient with pulmonary hypertension.


Considerations
This patient with pulmonary hypertension presents a unique challenge in anesthesia management. A vaginal hysterectomy typically requires general anesthesia, although, general anesthesia can exacerbate pulmonary hypertension and right heart failure. So in addition to the routine monitors as described by the American Society of Anesthesiologists, arterial blood pressure monitoring should be performed to provide beat-to-beat BP measurements, as well as the ability to frequently sample arterial blood gases. Blood gases are useful in the analysis of acid-base status, hemoglobin, and electrolytes. Given the status of her right ventricular dysfunction, it is not unreasonable to monitor her central venous pressure (CVP). If the surgical procedure were more complex or her condition had progressed, then a pulmonary artery catheter might also be indicated.

The major goal of an anesthetic is to avoid situations that might exacerbate her pulmonary hypertension. These include acidemia, hypoxia, hypercarbia, sympathetic stimulation, hypotension, and the use of drugs which exacerbate pulmonary hypertension such as nitrous oxide. Narcotics increase the carbon dioxide threshold, so even patients who are well narcotized require a higher end-tidal carbon dioxide level to initiate spontaneous respiration. Such a well narcotized state may worsen pulmonary hypertension and precipitate RV failure as well.


APPROACH TO
Pulmonary Hypertension

DEFINITIONS
PULMONARY HYPERTENSION: A sustained elevation of the pulmonary artery pressure, which can be idiopathic or secondary to diseases of the respiratory or cardiovascular systems.

COR PULMONALE: A right ventricular enlargement and dysfunction secondary to acute or chronic pulmonary hypertension.


CLINICAL APPROACH

Pathology of Pulmonary Hypertension
The pulmonary circulation is a low-pressure circulation. Elevation of the pulmonary vascular pressure can result from cardiac and respiratory disorders such as primary pulmonary hypertension, congenital heart disease, acquired valvular dysfunction, cardiomyopathy, myocardial infarction, acute and chronic thromboembolism, chronic respiratory disease, collagen vascular disorders, and end-stage liver disease. An elevated pulmonary artery pressure leads to increase in the right ventricular afterload, an increase in preload, tachycardia, and impaired contractility. The increased demand for oxygen in the face of a decreased perfusion of the right ventricle further perpetuates impairment of the right ventricular contractility, increases right ventricular pressure, and causes right ventricular failure. In patients with pulmonary hypertension, the perioperative risk for cardiopulmonary complications is related to the severity of the pulmonary hypertension and the degree of right ventricular dysfunction. Hypoxia, hypercarbia, and acidemia during anesthesia contribute to elevation of the pulmonary artery pressure.

The preoperative evaluation of a patient with pulmonary hypertension should focus on the severity of the disease and the presence of cor pulmonale. Clinical signs and symptoms of right ventricular failure and valvular incompetence include jugular venous distention, peripheral edema, liver congestion,
heart murmurs, and additional heart sounds. The patient’s ECG can demonstrate right axis deviation, right bundle-branch block (RBBB), right atrial enlargement, S1Q3T3 pattern, and electrolyte abnormalities. Echocardiography and cardiac catheterization are utilized to assess ventricular function and pressures, as well as pulmonary vascular resistance, and the response to intravenous or inhaled vasodilators. The respiratory system should be comprehensively evaluated and optimized prior to elective surgery.

The treatment for pulmonary hypertension includes continuing any pulmonary vasodilators, diuretics, and inotropes during the perioperative period. The surgical procedure, as well as the anticipated effects on the pulmonary circulation and the heart guides the choice of general or regional anesthetic technique.

Vaginal hysterectomy procedures can sometimes be done under regional anesthesia. Neuraxial regional anesthesia is associated with decrease in venous return and systemic blood pressure and the need for intravenous fluid load, all of which may exacerbate cardiac dysfunction. The maintenance of optimal fluid balance is critical in these cases. The right ventricular function is preload dependent; however, fluid overload can easily precipitate right heart failure. Neuraxial anesthesia such as spinal or epidural carries risks from the need for fluid preload, and the sympathectomy-induced hypotension, and are not be an optimal choice. In addition, the avoidance of hypercarbia and hypoxia due to heavy sedation is important, and the maintenance of hemodynamic stability is critical.

The prevention of endogenous catecholamine release during intubation and emergence can be achieved with opiates, intravenous anesthetics, and local anesthetics. Hypotension as a result of anesthetic induction, intraoperative fluid overload, excessive anesthesia, or blood loss is detrimental to right ventricular perfusion and should be avoided. The selection of an induction agent such as etomidate, administered slowly and at a reduced dose, facilitates the maintenance of a normal blood pressure. An invasive arterial blood pressure monitor aids in careful hemodynamic control, and monitoring adequacy of oxygenation and ventilation. If significant hemodynamic instability and fluid shifts are anticipated, central venous and pulmonary artery pressure monitoring as well as transesophageal echocardiography are indicated to guide fluid, inotrope, or pressor management.

Blood loss can result in hypovolemia, tachycardia, and decrease in oxygen carrying capacity, all of which can precipitate right ventricular failure and should be corrected promptly. For some procedures, laparoscopic techniques have the benefit of less blood loss, pain, and stress. However, patients with pulmonary hypertension may not tolerate the detrimental effects of the hypercarbia from the CO2 insufflation, or the reduction in preload while increasing afterload which is associated with pneumoperitoneum.


Comprehension Questions

20.1. A 45-year-old man with pulmonary hypertension presents to the emergency room with shortness of breath, jugular venous distension, peripheral edema, BP 87/46 mm Hg, HR 122 bpm, pulse oximeter oxygen saturation (SpO2) 91%, and hemoglobin 8.5 g/dL. Match the treatment (left column) with the order in which it would be administered.
A. Transfusion of red blood cells 1. First
B. Fluid bolus of 1 L normal saline 2. Second
C. Oxygen via face mask 3. Third
D. Furosemide dieresis 4. Fourth
E. Norephrine vasopressor infusion 5. Not at all

20.2. A 37-year-old woman with primary pulmonary hypertension, treated with intravenous epoprostenol infusion, is scheduled for emergency appendectomy. Which of the following statements regarding her anesthetic plan is correct?
A. Aggressive premedication with opiates is recommended.
B. Induction with standard dose of propofol will help in the control of hemodynamics.
C. Vasopressor use to treat hypotension is indicated.
D. The epoprostenol infusion should be discontinued to avoid hypotension.
E. Large fluid bolus before induction is indicated to avoid hypotension.

20.3. A 32-year-old woman with pulmonary hypertension secondary to mitral stenosis is undergoing laparoscopic nephrectomy for a renal mass. Half an hour after the start of the surgery, her SpO2 is 89%, her end-tidal CO2 is 55, BP 89/47, and HR 120. She has received 1 L of i.v. fluids. Which of the following is the most likely diagnosis for her hemodynamic compromise?
A. Left ventricular myocardial infarction (MI)
B. Ventilatory failure
C. Excessive IV fluid administration
D. Hypovolemia due to blood loss
E. Pulmonary embolism
F. A CO2 embolus from insufflation


ANSWERS
20.1. C, 1. Supplemental oxygen will improve oxygenation. Transfusing blood will increase oxygen carrying capacity and pulmonary artery pressure, but it will take time before the blood is available. Thus, E, 2, the vasopressor infusion is started next, to improve RV perfusion and contractility, and D, 3, the patient is diuresed to reduce the RV pressure. Answer B, a large fluid bolus, would further increase the RV pressure and worsen RV failure, and should not be done at all.

20.2. C. Hypotension should be treated with vasopressors to maintain RV perfusion and contractility. Premedication with high dose of opiates can lead to respiratory depression and hypercarbia and should be avoided. Induction agents should be used carefully and in reduced dose to avoid hypotension. Fluid overload can precipitate RV failure and fluids should be administered gradually and incrementally.

20.3. B. Ventilatory failure during laparoscopy with CO2 insufflation can lead to hypoxemia and hypercarbia, which elevates the pulmonary artery pressure and leads to right ventricular failure. E is a possible but less likely diagnosis. Patients with pulmonary hypertension are also at risk for pulmonary embolism in the perioperative period secondary to thromboembolic disease. C, excessive intravenous fluid administration, can also precipitate RV failure, although that would not be anticipated after only 1 L of saline. F, a CO2 embolus from insufflation is an unlikely possibility: CO2 emboli are usually catastrophic and temporally related to insufflation. D, hypovolemia secondary to blood loss is a possibility, although the surgeons have not noticed any bleeding. Answer A is incorrect. This young patient without risk factors for CAD is unlikely to have an MI of the left ventricle.


Clinical Pearls
➤ Patients with pulmonary hypertension may have considerable cardiac dysfunction and have increased risk of heart failure with hemodynamic alterations.
➤ Patients with pulmonary hypertension require a comprehensive preoperative evaluation which identifies the severity of the disease and baseline cardiac function, and assures that the patient’s condition is optimized prior to surgery.
➤ Both anesthetic and surgical techniques can worsen pulmonary hypertension and precipitate heart failure.
➤ The perioperative management of patients with pulmonary hypertension is critical to the reduction of cardiopulmonary complications and improvement of outcomes.

References

Klinger J. Pulmonary arterial hypertension: An overview. Semin in Cardiothorac Vasc Anesth. 2007;11:96-103. 

MacKnight B, Martinez E, Simon B. Anesthetic management of patients with pulmonary hypertension. Semin Cardiothorac Vasc Anesth. 2008;12:91-96. 

Ramakrishna G, Sprung J, Ravi B, Chandrasekaran K, McGoon M. Impact of pulmonary hypertension on the outcomes of noncardiac surgery. J Am Coll Cardiol. 2005;45:1691-1699. 

Subramaniam K, Yared J. Management of pulmonary hypertension in the operating room. Semin Cardiothorac Vasc Anesth. 2007;11:119-136.

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