Exam 1 Session 1
Stem
A 56 year old male, 70 kg, 5'8" tall man is brought to the operating room for a left upper lobetomy.
HPI: Patient noted the onset of a productive cough 6 weeks ago and an episode of hemoptysis 10 days ago. He was seen by pulmonary specialist who noted a 2 cm mass in his left upper lobe on chest x-ray. Fiberoptic bronchoscopy revealed irregularity of the left upper lobe bronchus, and biopsy revealed carcinoma. Metastatic workup was negative
PMH: Uncomplicated myocardial infarction 4 months ago. He notes angina with exercise over past month. A stress test 7 days ago showed minimal ST segment depression at a heart rate of 120 beats per min without angina. An echocardiogram revealed an ejection fraction 55%.
Medications include diltiazem and nitroglycerin PRN. He has no allergies. He smoked 2 packs of cigarettes per day for 25 years until 10 days ago. He drinks an occasional beer.
PHYS Exam: P 72, BP 140/80, R 20, T 37.1 C. His airway appears normal. Chest auscultation reveals expiratory wheezes over the left posterior upper lung field. Cardiac exam is normal. He has no organomegaly or peripheral edema.
X-ray: 2 cm mass and small infiltrate left upper lobe
EKG: Q waves in II, III, aVf with T wave inversion in same leads
Labs: Hgb 14.5 gms/dl, normal electrolytes and normal coagulation studies.
He arrives in operating room at 10:00 am with 1" nitropaste, having taken his diltiazem at 7:00 am
Intra-operative Management
Topic 1
Would you induce with thiopental?
answer
Yes, thiopental is a reasonable induction agent for this case.
Why or why not?
Thiopental provides rapid and reliable induction of anesthesia. Thiopental does cause dose dependent cardiac depression and vasodilation, however considering the patient’s reassuring cardiac history the patient should be able to tolerate an induction with thiopental Note:
You will probably no longer be asked a question on thiopental. A more reasonable question would be “would you induce with etomidate?”. These questions, I believe, are just testing your knowledge on the benefits and risks of different induction agents. In my opinion, they just want you to choose an agent and be able to articulate why you chose that agent.answer
Propofol?
answer
I would choose propofol over thiopental. Thiopental has a long half life and is often associated with unpleasant side effects several hours post procedure such as headache, somnolence and nausea. Propofol on the other hand has rapid clearance. It also has bronchodilatory and antiemetic effects that may prove beneficial for this case.The surgeon request a double lumen tube. You respond?
A double lumen tube would be appropriate for this case. A double lumen tube is both easier to place and less likely to dislodge than a bronchial blocker.answer
How do you confirm position?
answer
The position can be confirmed by auscultation. However, the gold standard is using a fiberoptic. In a properly seated left sided double lumen tube, tha tracheal view should show an inflated blue bronchial balloon just visible beyond the carina on the left side. Going down the right main stem bronchus should show a characteristic early take off of the right upper lobe.
Is a right sided tube appropriate?
answer
A right sided tube would be reasonable. I would discuss with the surgeon to determine is a right sided tube would be needed from a surgical stand point. A right sided tube is slightly more difficult to place as there is an additional orifice that needs to line up with the right uper lobe bronchus.
Topic 2
Is nitrous opioid anesthesia appropriate? Why or why not?
I would not use a nitrous opioid anesthesia as the primary anesthetic. The surgeon will be operating very close to vital structures. To insure ideal surgical conditions, I would adequately anesthetize, paralyze and mechanically ventilate the patient. I would not be able to achieve adequate anesthesia using only nitrous and opiates. Nitrous is also associated with increased rates of atelectasis compared to other inhalational agents, which may contribute to post op complications.answer
Your choice?
answer
I would use an inhalational agent.
Would halothane be preferable if the patient has reactive airway disease?
I would pick sevoflurane as it has a most profound bronchodilatory effect if I am concerned with reactive airway disease. Halothane has traditionally been used as a bronchodilator but it is no longer available due to adverse side effects associated with halothane Note: Halothane is also another agent that is probably no longer tested. Halothane is not available in the United States. A similar question that may be asked is “would desflurane be preferable if the patient has reactive airway disease?”answer
Topic 3
After 20 mins of one lung ventilation, SpO2 decreased from 99% to 90%. Your interpretation and response?
The most common cause of hypoxemia in one lung ventilation is due to shunting, but I would also consider other possible causes such as dislodgment of airway, bronchospasm, airway injury, mucous plug etc.
I would inform the surgeon, and confirm the tube position with fiber optic. Understanding that some level of shunting is unavoidable, I would be comfortable with the current management as long as SpO2 remains above 92%answer
What if the SpO2 drops to 80%
answer
I would inform the surgeon again regarding the change.
Then I would increase the FiO2 to 100%
I would again confirm correct tube positioning with with fiberoptic
I would perform a recruitment maneuver on the ventilated lung
Then I would attempt to increase to PEEP 10 cmH20 on the ventilated lung
If the hypoxemia persists, I would then provide CPAP at 5-10 cmH20 or attempt high frequency ventilation on the non ventilated lung
If hypoxemia continues I would discuss with the surgeon about mechanically restricting blood flow to the operative lung
Topic 4
The surgeon loses control of the pulmonary vein and the patient loses 1200 ml blood in two minutes. Two units of packed cells are available. How to manage?
I would rapidly administer 2 L of crystalloid solution. After 2 L I would reassess the patient’s hemodynamic status by analyzing respirophasic systolic pressure variations in the arterial waveform, if available. I would also look at heart rate, blood pressure, CVP as additional data points to assess volume statusanswer
The blood pressure is not responding to volume replacement. You plan?
answer
I would inform the surgeon. I am concerned about continued rapid blood loss. I would rapidly start transfusing the available pRBCs.
I would initiate a vasopressor to help maintain adequate tissue perfusion until additional blood products are available
I would initiate a massive transfusion protocol to mobilize resources to get additional blood products and get a rapid transfuser.
I would transfuse at a 1:1:1 ratio of pRBC, FFP and platelets
Through the resuscitation I would send labs (CBC, PTT, BMP, INR, Fibrinogen and TEG if available) to guide therapy
Ischemia on ECG. How does this influence your management?
I am concerned about inadequate oxygen delivery to the heart and other end organs. This may be due to inadequate volume and/or inadequate oxygen carrying capacity due to rapid blood loss. I would continue current resuscitation efforts.answer
What is your plan? Why?
answer
The goal is to optimize O2 supply and reduce demand. I would attempt to maintain a normal heart rate and consider a beta blocker with the understanding that there may be significant risk in the setting of resuscitation. Maintain normal blood pressure with vasopressor support. I would also be mindful of volume administration since overdistension of the left ventricle can cause increased demand.
Topic Headers
Topic 1: Induction Topic 2: Anesthetic Selection Topic 3: Intraoperative Hypoxia Topic 4: Massive Blood Lossanswer
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50d6b8b @ 2023-06-07