Exam 1 Session 1 Postoperative
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
Post-operative Management
Topic 1
How would you decide suitability for extubation?
answer
I decide to extubate if the patent meets my extubation criteria.
The patient must be in stable medical condition. The patient no longer requires aggressive resuscitation and is not on multiple high dose pressors to main blood pressure.
The patient must be able to maintain SpO2 of greater than 90% with an FiO2 < .4, or a PaO2/FiO2 > 150
The patient is fully reversed from paralytics
Patient is spontaneously breathing at a reasonable rate and adequate tidal volumes on no or minimal support
For high risk patient, as in this case I would also require the patient awake or easily arousable to insure recovery of protective laryngotracheal and upper airway reflexes and upper airway tone
Rationale?
Adverse respiratory events leading to significant long term morbidity is more often associated with extubation. Applying a consistent criteria minimizes the chance of extubating a patient who is not ready for extubation.answer
How does criteria for this patient differ from ASA-1 cholecystectomy?
answer
I would apply the same criteria to all my patients. Although the risk of needing re-intubation and/or significant respiratory complication is much lower in a healthy patient undergoing a low risk surgery. I believe, maintaining a consistent criteria can reduce significant desaturations in pacu, larygospasm, hypoventilation and prolonged pacu stays.
Topic 2
Assume ABG at end of surgery with double lumen ETT and bilateral ventilation shows PaO2 65, PaCO2 58, pH 7.29 with a FiO2 .5 and spontaneous ventilation. Interpret
answer
The PaO2/FiO2 ratio is about 130. The PaO2/FiO2 ratio is a clinical indicator of hypoxemia. The PaCO2 is high resulting in respiratory acidosis indicating inadequate ventilation.
How will you proceed?
answer
The patient is unable to adequately ventilate to maintain normocarbia. Additionally the patient does not meet an extubation criteria of a PaO2/FiO2 > 150. I would keep the patient intubated and mechanically ventilated.
Why?
answer
The patient is at high risk of hypoxemia and hypoventilation following extubation. At worst if undetected the patient is at risk of long term neurological injury or cardiovascular collapse. The more likely scenario is that the patient will likely need to be reintubated.
If you decide to ventilate in the ICU will you change a double lumen ETT to single lumen ETT?
I would switch out the double lumen tube. There is very little familiarity with double lumen tubes outside the operating rooms, which can increase the chance of user error. If I felt that the exchange might be difficult or if it expected that the patient would remain intubated for a short period of time, it would be reasonable to leave a left sided double lumen tube.answer
What ventilations settings would you use?
I would utilize a lung protective ventilation strategy. I would use SIMV. I would target a tidal volume to 6-8 ml/kg of ideal body weight, and set a minimum rate to achieve a EtCO2 of 40. I would add 5 of PEEP to decrease the risk of atelectasis.answer
SIMV vs PCV?
answer
I would use synchronized intermittent mandatory ventilation over pressure controlled ventilation, if the patient is initiating breaths. SIMV may be used to reduce the work of breathing, and support ventilation while weaning from controlled ventilation. With PCV, frequent adjustments may be needed because the tidal volume will change with change in lung compliance.
Discuss PEEP
PEEP prevents alveolar collapse and can maintain end-expiratory lung volume recruited during inspiration. It’s important to know that PEEP can have detrimental hemodynamic effects such as decreased cardiac output, hypotension and increased intracranial pressure.answer
Topic 3
Would PCA be a good choice?
answer
Yes a PCA would be a reasonable choice for post op pain control. I would also consider a multimodal approach utilizing other oral analgesics such as NSAIDs/Acetaminophen and a regional anesthetic technique.
Why?
Compared with conventional parenteral analgesia, PCA use is associated with higher opioid consumption and more pruritus but provides better pain control and often results in greater patient satisfaction.answer
Is a thoracic epidural a better choice?
answer
I believe a thoracic epidural is better for certain patients. For most patients, however, adequate analgesia and high satisfaction can be achieved without a thoracic epidural.
Why?
A thoracic epidural can significantly decrease postoperative opioid requirements. I would use a thoracic epidural for patients where opioids may not be as effective or should be avoided. For example, in patients who have chronic pain, severe sleep apnea, severe COPD, etc.answer
If epidural is in place, which medication would you administer?
answer
I would use a solution that contains either ropivacaine or bupivacaine and an opiate such as fentanyl.
Why?
Both ropivacaine and bupivacaine tend to have less motor blockade compared to other local anesthetics at equal analgesic doses. I would also add opiates because it improves the analgesic effect of local anesthetics allowing me to use a lower concentration of local anestheticanswer
Topic 4
answer
8 hours after surgery, the patient complains of chest pain and you note new ST segment elevation on the bedside monitor. How will you proceed?
I would order a stat 12 lead EKG, Chest X-ray, troponin, CBC, BMP and coagulation studies. I would administer an aspirin. I would also administer a beta blocker if the patient is hemodynamically stable and there is no evidence of bradycardia, heart block, or heart failure. I would call cardiology for evaluation for possible urgent percutaneous coronary intervention (PCI) and adminster a P2Y12 Inhibitor inline with my institution’s PCI protocol
30 mins later, his blood pressure is 80/30 and you note tachypnea and diffuse rales. Discuss evaluation and management.
answer
Initial evaluation would focus on the patient’s respiratory and hemodynamic status. I would evaluate respiratory status using SpO2, ABG, CXR and work of breathing. If the patient appears to be in respiratory distress, I would secure an airway and provide mechanical ventilatory support.
To assess the patient’s hemodynamic status I would assess the patient’s blood pressure, heart rate, and perform a focused physical and a bedside TTE if available. I would initiate norepinephrine to maintain a MAP greater than 65. Then, I would facilitate the patient getting a percutaneous coronary intervention as quickly as possible.
Topic 5
Following extubation and at time of discharge from ICU, the patient complains of numbness over ulnar distribution of right forearm and hand. What might be the cause?
answer
Ulnar neuropathy following surgery is poorly understood but it is likely a combination of multiple factors including mechanical injury due to improper positioning and patient comorbidity such as diabetes, body habitus, etc. Other possible but much less likely causes for the symptoms include a lesion at the C8 nerve root, Cervical syringomyelia, or a small cortical brain infarct.
How will you evaluate?
answer
I would start with a physical exam. I would carefully examine and try to identify any motor deficits. I would then test sensory to both pinprick and light touch. Following my exam, I would refer the patient to a specialist for a confirmatory electromyography.
Is there a treatment for this?
answer
Initial management is conservative. Most peripheral nerve neuropathies following surgery tend to be temporary. Therapy is primarily directed toward activity modification to reduce possible further injury. For severe symptoms or progressive symptoms a referral to a surgical specialist may be warranted for possible surgical intervention
What will you tell the patient?
answer
I would apologize to the patient, and explain that improper positioning during surgery may have contributed to the patient’s symptoms. I would tell the patient that I would provide ongoing support to ensure proper management and treatment to minimize any long term consequences.
Topic 6
4 days after surgery, the patient’s bilirubin is 6.5 mg/dl. Surgeon questions if anesthesia might be the cause. You respond?
answer
In the past, a common inhalational anesthetic halothane was often associated with hepatotoxicity. Modern inhalational anesthetics are not associated with hepatotoxicity, therefore it is unlikely that the elevated bilirubin is due to an anesthetic medication.
Discuss further evaluation?
The differential diagnosis is extremely broad for elevated bilirubin. Evaluation should start with a careful history. Patients should be asked about other symptoms, recent medications, prior history of jaundice, recent travel and so forth. Following a history and physical, laboratory studies should be ordered. I would order a conjugated and unconjugated bilirubin, ALT, AST, Alk phos, PTT and INR. Further tests would depend on this initial assessment.answer
Go to Additional Topics
50d6b8b @ 2023-06-07