UBP 3.4 (Short Form): Pulmonary – Mediastinoscopy

Question 1

What do you think of his shortness of breath?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 1

I am very concerned about his shortness of breath,

recognizing that there are a number of clinical conditions associated with his medical history that could be causing or contributing to his symptomatology, such as:

1. pulmonary disease resulting from his tobacco abuse (i.e. COPD and/or pneumonia);
2. mass-induced ventilation perfusion mismatching;
3. mass-induced post-obstructive pneumonia;
4. superior vena cava syndrome secondary to neoplastic invasion of the vessel wall (usually in association with intravascular thrombosis), with the resultant obstruction of venous drainage leading to mucosal edema and venous engorgement of the airways and subsequent dyspnea, orthopnea, and coughing;
5. mass compression of the heart or other great vessels (i.e. direct cardiac compression, pericardial effusion, pulmonary artery compression);
6. cardiac disease in this older male smoker with hypertension and known carotid disease; or
7. a late finding of Lambert-Eaton Myasthenic Syndrome (LES), a known paraneoplastic syndrome that may also present with signs of autonomic dysfunction, such as constipation and orthostatic hypotension.

Clinical Notes:

• There are a number of paraneoplastic and paraendocrine syndromes associated with cancer.
• Common Paraneoplastic Syndromes:
  
  1. Humoral Hypercalcemia – Tumor release of parathyroid hormone-related peptides can lead to muscle weakness, cardiac arrhythmias, nausea, vomiting, and renal failure.
  2. Syndrome of Inappropriate secretion of Antidiuretic Hormone (SIADH) – tumor production of arginine vasopressin can lead to hyponatremia, decreased serum osmolarity, and inappropriately increased urine osmolarity in the setting of euvolemia and normal thyroid and adrenal function.
  3. Cushing’s Syndrome – increased secretion of ACTH or CRH can lead to hypokalemia, alkalosis, hypertension, and psychosis.
  4. Lambert-Eaton Myasthenic Syndrome – most commonly associated with small cell lung cancer. 40-60% of patients presenting with LES are subsequently diagnosed with a malignancy (3% of cases of small cell lung cancer are associated with LES).
• Paraendocrine Syndrome:
  
  1. Carcinoid syndrome – the most common extra-intestinal location of carcinoid tumors is the lung.

Question 2

With additional investigation you find that the patient was recently diagnosed with Lambert-Eaton Myasthenic Syndrome (LES). Tell me about this syndrome.

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 2

Lambert-Eaton myasthenic syndrome (LES) is a syndrome in which the formation of antibodies to prejunctional voltage-gated calcium channels results in a reduced release of acetylcholine at the motor end-plate.

Patients characteristically present with proximal weakness of the lower extremities (sometimes progressing to involve the upper extremities) and signs of autonomic dysfunction, such as dry mouth, impotence, constipation, and orthostatic hypotension.

In contrast to Myasthenia Gravis where strength improves with rest, patients with LES show improved strength with muscle activity.

While bulbar involvement and respiratory compromise are less common than with Myasthenia Gravis, they do sometimes occur (respiratory weakness is a late finding).

In the case of malignancy, treatment begins with –

1. cancer therapy. … Other interventions include:
2. plasma exchange,
3. intravenous immune globulin therapy,
4. the administration of prednisone or azathioprine for immunosuppression,
5. increasing the release of acetylcholine with 3,4-diaminopyridine (should be continued up to the time of surgery), or
6. decreasing the degradation of acetylcholine with pyridostigmine (a cholinesterase inhibitor).

Question 3

His sodium is 129 mEq/L. What do you think may be the cause?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 3

Given the patient’s medical history, his hyponatremia could be the result of –

• SIADH, a paraneoplastic syndrome associated with malignancy, or it could possibly be the result of
• diuretic administration if this type of medication were being used to treat his hypertension (while loop diuretics can also lead to hyponatremia, they are less likely to do so than thiazide diuretics).

Further evaluation would be helpful in determining the etiology.

Hyponatremia secondary to SIADH is associated with –

• normovolemia
  
  • (no signs of hypovolemia, such as orthostatic hypotension, tachycardia, or dry mucous membranes;
  • no signs of hypervolemia, such as peripheral edema, ascites, or pulmonary edema),
• a normal total body sodium level, and
• an elevated urine osmolality and urinary sodium concentration (increased urine osmolality and urinary sodium concentration result from reduced urine volume).

On the other hand, hyponatremia secondary to diuretic use is associated with –

• hypovolemia (however, this reduction in blood volume may be attenuated by the stimulation of ADH secretion, with subsequent water retention),
• a low total body sodium level, and
• an elevated urinary sodium concentration.

Question 4

Basing your decision on this low sodium level,

would you proceed with surgery?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 4

Since proceeding with surgery in the presence of a sodium concentration under 130 mEq/L places the patient at risk of developing significant cerebral edema,

I would prefer to delay the surgery until the cause of the hyponatremia could be determined, and the sodium level corrected.

However, I would discuss the pros and cons of delaying the case with the surgeon since even a short delay may be unacceptable if an urgent diagnosis is needed.

Question 5

Does his carotid artery disease concern you?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 5

His carotid artery disease does concern me because of the risk of inadequate cerebral perfusion secondary to a hypertension-induced rightward shifting of the cerebral autoregulation curve and/or a surgically-induced decrease in cerebral blood flow secondary to compression of the innominate artery.

A patient with carotid artery disease may be unable to compensate adequately for these insults resulting in neurologic damage.

In fact, because of the risk of innominate artery compression,

mediastinoscopy is relatively contraindicated in a patient with cerebrovascular disease.

In addition to shifting the cerebral autoregulation curve to the right, his poorly controlled hypertension places him at increased risk for cerebral ischemia due to blood pressure lability.

Finally, I would be even more concerned if I believed that his cough and shortness of breath were secondary to superior vena cava syndrome, recognizing that partial or complete obstruction of the superior vena cava could further compromise cerebral perfusion (impaired drainage of cerebral veins → increased cerebral venous pressure → increased ICP and impaired cerebral perfusion).

Therefore, if avoiding mediastinoscopy were not an option, I would monitor the patient for signs of innominate artery compression (i.e. right radial arterial line or right upper extremity pulse oximeter tracing), attempt to optimize his blood pressure, and avoid any additional factors that could compromise cerebral perfusion such as hypotension, additional obstruction of cerebral venous drainage, hypercapnia, and acidosis.

Clinical Notes:

• Previous mediastinoscopy is a strong contraindication to mediastinoscopy.
• Relative contraindications to mediastinoscopy include:
  
  1. severe tracheal deviation,
  2. cerebrovascular disease,
  3. severe cervical spine disease with limited neck extension,
  4. previous chest radiotherapy, and
  5. thoracic aortic aneurysm.

Question 6

Are you concerned about his blood pressure?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 6

I am concerned about his blood pressure because poorly controlled hypertensive patients are more prone to –

intraoperative end-organ ischemia (i.e. myocardial infarction and stroke), arrhythmias, congestive heart failure, hypotension, and hypertension.

The potential for blood pressure lability and a rightward-shifted cerebral autoregulation curve is even more concerning in this patient with carotid artery disease, who is already at increased risk of compromised cerebral perfusion (i.e. cerebral vascular disease, mediastinoscopy, possible superior vena cava syndrome).

Clinical Notes:

• For patients > 50 years of age: a systolic blood pressure in excess of 140 mmHg is a more important risk factor for cardiovascular disease than is elevated diastolic pressure (this does not hold true for patients younger than 50 years of age).
• For patients 40-70 years of age: each incremental increase in SBP of 20 mmHg or DBP of 10 mmHg above 115/75 mmHg doubles the risk of cardiovascular disease.
• Hypertension in children is diagnosed when repeated blood pressure measurements are > the 95^th percentile after making adjustments for age, height, and gender.

Question 7

What would you do?

(previous question – are you concerned about his blood pressure?)

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 7

I would perform a careful history and physical focused on blood pressure medications, the adequacy of blood pressure control, any identifiable cause of his hypertension (i.e. sleep apnea, kidney disease, or hormonal imbalance), and the presence of associated end-organ damage (cardiac, cerebral, renal, and vascular disease).

I would also obtain an ECG and measure electrolytes, blood urea nitrogen, and creatinine to further evaluate end-organ damage and identify metabolic derangements secondary to blood pressure medications.

Finally, if the urgency of the case did not allow for blood pressure optimization over several weeks, I would administer pharmacologic agents to lower his blood pressure to around 140/90 mmHg while carefully monitoring for any signs of cerebral ischemia

(I would not attempt to normalize his blood pressure since his cerebral autoregulation curve is shifted to the right).

Clinical Notes:

• A reasonable approach to the management of preoperative hypertension for an elective procedure is to delay elective surgery for at least 6-8 weeks to optimize the blood pressure of any patient who:
  
  1. has SBP readings > 180 mmHg or DBP reading > 110 mmHg,
  2. has stage 1 or stage 2 hypertension with concomitant end-organ damage, and/or
  3. is undergoing cardiac surgery, carotid surgery, or pheochromocytoma resection.
     
     • However, the decision to delay any case (and the length of that delay) must weigh the risks of blood pressure optimization against the risk of surgical delay.
• Classification of Blood Pressure (adults >/= 18 years of age)*:
  
  • Normal: SBP < 120 and DBP < 80 mmHg
  • Prehypertensive: SBP of 120-139 or DBP of 80-89 mmHg
  • Stage 1 Hypertension: SBP of 140-159 or DBP of 90-99 mmHg
  • Stage 2 Hypertension: SBP > 160 or DBP > 100 mmHg
    
    • Based on the average of 2 or more readings taken in the seated position on two separate occasions.
• Causes of hypertension include:
  
  1. chronic kidney disease,
  2. renovascular disease,
  3. chronic steroid therapy (Cushing’s syndrome),
  4. sleep apnea,
  5. drugs (i.e. cocaine, amphetamines, certain dietary supplements, oral contraceptives),
  6. alcohol abuse,
  7. obesity/metabolic syndrome,
  8. thyroid or parathyroid disease,
  9. pheochromocytoma, and
  10. coarctation of the aorta.
• Signs of end-organ damage include:
  
  1. left ventricular hypertrophy,
  2. angina,
  3. myocardial infarction,
  4. congestive heart failure,
  5. coronary artery disease,
  6. stroke,
  7. transient ischemic attack,
  8. chronic kidney disease,
  9. retinopathy, and
  10. peripheral artery disease.

Question 8

You discover the patient is taking an ACE inhibitor.

Would you continue this medication throughout the perioperative period?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 8

Given the fact that his blood pressure is already poorly controlled, I would continue his ACE inhibitor recognizing that this does increase the risk of intraoperative hypotension.

Therefore, I would be prepared to quickly identify and treat any hypotension in order to maintain adequate cerebral perfusion pressure in this patient with carotid artery disease.

Question 9

Considering this patient’s hypertension and carotid artery disease, do you think that a reasonable physician would proceed with this case?

(A 62-year-old male with suspected lung cancer presents for mediastinoscopy for staging and diagnosis after sputum cytology and needle biopsy failed to provide a definitive diagnosis. Notes from his primary care physician indicate that in the last 6 months the patient has developed a persistent cough, worsening shortness of breath, orthostatic hypotension, and constipation. His medical history is also significant for tobacco use, carotid artery disease, and hypertension. VS: P = 87; BP = 175/103; R = 10; T = 36.6 °C)

Answer 9

Given this patient’s significant hypertension and carotid artery disease, I would prefer to delay the case to control his blood pressure and obtain a vascular surgeon consult.

However, if after discussing the risks and benefits with the surgeon, it was determined that the benefits of timely diagnosis and/or staging of the carcinoma outweighed the risk of cerebrovascular compromise, I would proceed taking the precautions previously discussed.