A 55-year-old female with a history of renal cell carcinoma with metastases to the spine is scheduled for a spinal separation procedure to facilitate radiation therapy. The surgical procedure was uneventful. Following skin closure, there was a sudden drop in oxygen saturation to 86% with an increase in heart rate to 124/min and blood pressure of 85/41 mm Hg. The peak airway pressure was 25 cm H2O and the ETCO2 is 15 mm Hg. 100% oxygen was administered and the patient was started on an epinephrine infusion to support hemodynamics.
Which of the following statements is LEAST likely to be true if you are considering a diagnosis of pulmonary embolism in this patient?
Correct Answer: D
Advancing age, immobilization, and a diagnosis of cancer confer an increased risk of deep vein thrombosis and pulmonary embolism (PE). Contrast-enhanced chest CT scan is the most commonly used modality to confirm the diagnosis of a PE. As PE represents a perfusion defect, there is an increase in dead space ventilation in these patients. In addition to initial stabilization, volume infusion, and vasopressor therapy, systemic anticoagulation is initiated in most patients with a PE as long as there are no contraindications. Recent surgery, especially in closed spaces like brain/spinal cord, active bleeding, and malignant hypertension are considered contraindications for systemic anticoagulation. Thrombolytic therapy is reserved for patients with PE who present with hemodynamic instability. Although it could rapidly restore pulmonary circulation and improve right ventricular function, it confers a higher risk of bleeding. Catheter-directed thrombolysis can be considered in patients in whom the risk of bleeding with systemic therapy outweighs the benefits.
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Which of the following statements regarding monitoring modalities for venous air embolism (VAE) is MOST accurate?
Correct Answer: B
Transesophageal echocardiography (TEE) is the most sensitive monitoring modality to detect venous air embolism. TEE can detect as little as 0.02 mL/kg of air. Precordial Doppler is the most sensitive noninvasive monitoring modality with the ability to detect 0.05 mL/kg of air. Other available monitoring modalities for the detection of VAE include transcranial Doppler, esophageal stethoscope, pulmonary artery catheter, end tidal carbon dioxide and nitrogen. Changes in end tidal nitrogen are seen to occur 30 to 90 seconds prior to the changes in end tidal carbon dioxide. Although their sensitivities seem equivalent, for large volume entrainment, the sensitivity of end tidal nitrogen might exceed that of end tidal CO2 . Pulmonary artery catheters are fairly insensitive monitors for this purpose. The mill-wheel murmur auscultated with an esophageal stethoscope has a low sensitivity and is not an early sign (1.7 mL/kg/min).
A 40-year-old female is admitted to the intensive care unit with worsening shortness of breath. She states that she had a clot in her lung “a long time ago” for which she “took blood thinners for a few months.” Her initial transthoracic echocardiogram reveals enlarged right-sided chambers with severe tricuspid regurgitation and a large thrombus in the pulmonary artery with severe pulmonary hypertension.
This patient is MOST likely to belong to which of the groups of the World Health Organization clinical classification of pulmonary hypertension.
The World Health Organization clinical classification of pulmonary hypertension categorizes this diagnosis into groups based on similarities in pathophysiology, clinical presentation, and therapeutic measures. The five broad groups are as follows:
Given the clinical presentation, this patient seems to have a large clot in the pulmonary artery with enlarged right-sided chambers and pulmonary hypertension. She most likely has CTEPH and belongs to group 4.
A 56-year-old male with 30-pack year smoking history, CAD, and advanced liver disease due to alcoholic cirrhosis is being evaluated for a liver transplantation. He complains of worsening shortness of breath. His heart rate is 110/min, blood pressure is 97/64 mm Hg, respiratory rate is 32/min, and saturation 90% on 5 L/min nasal cannula. When asked to sit up in bed, the patient states that he “usually breathes better” when lying supine.
Which of the following is the MOST likely pathophysiology behind the diagnosis?
Correct Answer: C
The development of intrapulmonary vascular dilatations (IVPD) in the presence of advanced liver disease and portal hypertension results in hepatopulmonary syndrome (HPS). Several mediators included nitric oxide, endothelin 1, TNF alfa, and vascular endothelial growth factor have been implicated in the development of these IVPDs. The dilation of these blood vessels results in shunting of blood, leading to V/Q mismatch, hypoxemia, and an increased alveolar arterial oxygen gradient. These IVPDs tend to occur predominantly in the base of the lungs, resulting in worsening of the shunt while upright. This manifests as platypneaorthodeoxia. Contrast-enhanced echocardiography can aid with the diagnosis of HPS and microaggregated albumin (MAA) can help distinguish and quantify hypoxemia resulting from IVPD in patients with other lung parenchymal disorders. Liver transplantation is the definitive treatment. Although several experimental medical therapies have been tried, none of them have consistently shown to be of benefit in the treatment of HPS.
A 67-year-old female with a history of DVT/PE, hypertension, diabetes mellitus, and coronary artery disease undergoes a hemicolectomy with end ileostomy for colorectal carcinoma. On postoperative day 4, she aspirates following an episode of emesis. She is intubated and transferred to the ICU for further management. Ventilator settings are as follows:
Her HR is 105 bpm; BP is 127/64 mm Hg, saturation 85%. Her most recent ABG reveals:
Which of the following interventions is MOST likely to improve the oxygen delivery in this patient?
Increase in dead space ventilation contributes to the V/Q mismatch in patients with pulmonary embolism. Oxygen attached to hemoglobin contributes a great extent to the overall oxygen content in the arterial system. The other factors that contribute to the arterial oxygen content include the oxygen saturation and partial pressure of oxygen in the blood or the dissolved oxygen.
This is depicted by the equation, CaO2 = (1.34 × Hgb × SaO2 ) + (0.0031 × PaO2 ).
The role of the dissolved component of oxygen is negligible as it is multiplied by a factor of 0.0031. The saturation of oxygen has an upper limit of 100% which limits its ability to improve the content above a certain limit. Consequently, PRBC transfusion is most effective in increasing the oxygen content of arterial blood, especially in an anemic patient. Oxygen delivery is a product of oxygen content and cardiac output. Although inotropes could increase cardiac output, this patient has appropriate hemodynamics at this time which would not warrant inotropic support.
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