A 70-year-old male is admitted to the ICU following esophagectomy for esophageal carcinoma via laparotomy and right thoracotomy. He has a history of former tobacco use (40 pack-years), hypertension, type 2 diabetes, non–obstructive coronary artery disease, and stage 3 chronic kidney disease.
A thoracic epidural was placed preoperatively and started during the surgery. Postoperatively, the epidural infusion consists of ropivacaine 0.1% with fentanyl 2 µg/mL at 6 mL/h. Initially, the patient complained of rightsided shoulder pain that was relieved with addition of scheduled acetaminophen. On postoperative day 1, the patient is comfortable at rest, but complains of a small area of distal abdominal incisional pain that is uncontrolled when he moves or coughs. He has minimal chest wall pain.
Which of the following is the most appropriate initial change to his pain regimen?
Correct Answer: B
Pain following thoracic surgery can be a serious issue for patients, not only because of its intensity and duration but also because of its adverse effects on pulmonary function and recovery.
Opioids are considered a mainstay of significant postoperative pain management. However, a narrow therapeutic range and potential for sedation and respiratory depression are general limitations of this class of drugs. Morphine (A) in particular should be used with caution in elderly patients and patients with renal disease due to its active metabolites and long-lasting effects. Although addition of an intravenous opioid might improve this patient’s pain control, his major complaint has to do with pain with activity, and scheduling morphine is not the most appropriate first step.
NSAIDs are reversible COX inhibitors that can be very effective for treating the inflammatory component of postoperative pain. In general, meta-analyses of randomized controlled trials report improved pain scores and reduced analgesic use when intravenous morphine combined with ketorolac is compared with intravenous morphine alone. With respect to thoracotomy pain, the addition of NSAIDs as part of a multimodal pain regimen can be especially effective to treat shoulder pain that is refractory to epidural anesthesia, as well as to reduce overall opioid requirements. However, NSAIDs have also been associated with decreased platelet function, gastric erosions, increased bronchial reactivity, and decreased renal function. NSAIDs should be used with caution in patients who are elderly or have known risk factors for postoperative renal failure, including hypertension, diabetes, and preexisting renal disease. This patient’s shoulder pain has already been relieved by acetaminophen, which is a weak COX inhibitor. Although NSAIDs may also improve his incisional pain, scheduled ketorolac (A) would not be the best option given his age and comorbidities.
Currently, in the absence of contraindications, a thoracic epidural may be considered the “standard” of analgesia for open thoracotomy. Coverage of dermatomes far from the site of insertion can be achieved by increasing volume of local anesthetic or replacing epidural fentanyl with a hydrophilic opioid such as hydromorphone (B) or morphine, as highly lipid-soluble agents are associated with narrower dermatomal spread, and given his pain is concentrated to a small area, the fentanyl may be spreading too much.
Paravertebral catheters (C) have been shown to have similar efficacy to epidurals following thoracic surgery and are a reasonable alternative. However, this patient’s epidural appears to be functioning, given that he has no chest wall pain and only a small distal area of pain. Before proceeding with another invasive procedure, it is more appropriate to attempt to augment the existing epidural by changing the solution or increasing the rate.
Increasing the concentration of ropivacaine in the epidural while halving the rate (D) would potentially increase the density of the blockade, but not the spread.
References:
A 48-year-old female with no significant past medical history presents to the emergency department (ED) with 7 days of dyspnea, fatigue, and 2 days of coughing up frank blood. Chest CT shows a large right pulmonary arteriovenous malformation (PAVM) extending the width of the right middle lobe, which is thought to be the source of bleeding. The patient is admitted to the ICU for monitoring and while in the ICU she has an episode of large volume hemoptysis (more than 300 mL) associated with desaturation to 83%, which improves to 98% with deep suctioning and oxygen delivery via non-rebreather face mask.
The patient is intubated using a 39F left-sided double lumen tube (DLT) and the endobronchial cuff is inflated to isolate her right lung and prevent blood from entering the left lung. Immediately after intubation her vital signs are:
After confirming appropriate tube position with bronchoscopy, leftsided one lung ventilation is initiated. Approximately 10 minutes after start of one lung ventilation, her vital signs are as follows:
Which of the following factors correlates with increased risk of hypoxemia during one lung ventilation?
During one lung ventilation while both lungs are perfused only one lung is ventilated. This invariably leads to transpulmonary shunting and impairment in oxygenation. Hypoxemia typically occurs within the first 10 to 30 minutes of initiation of OLV and stabilizes or slightly increases as hypoxic pulmonary vasoconstriction (HPV) increases over the next 2 hours.
A number of factors may be helpful in predicting oxygenation during OLV:
Side of ventilation—The right lung is larger and 10% better perfused than the left lung. Thus, it is not surprising that right-sided OLV is better tolerated than left-sided OLV. The overall mean PaO2 is 100 mm Hg higher during stable right-sided OLV than during left-sided OLV (A).
Baseline Spirometry—Studies consistently show that patients with better spirometric lung function are more likely to desaturate during OLV. This is due to a dramatic increase in shunt fraction on initiation of one lung ventilation. Oxygenation often improves as HPV diverts blood flow to the ventilated lung with decreasing shunt fraction over time.
Typically, patients with an obstructive spirometric pattern tolerate OLV very well. In a chronically diseased lung, perfusion to areas with poor function is decreased because of chronic HPV. Thus, there is a less dramatic change in shunt fraction when OLV is initiated (B).
Baseline PaO2—Abnormally low arterial oxygen tension (PaO2 ) as found by blood gas analysis during two lung ventilation is a reliable indicator of abnormal lung function and a predictor of hypoxemia during OLV. PaO2 levels during two lung ventilation are strongly and positively correlated with PaO2 during OLV (C).
Position—Patient’s position during OLV is a factor in oxygenation. Positioning ventilated lung in the dependent position decreases VQ mismatch as perfusion to the ventilated lung increases because of gravity, whereas blood flow to the nonventilated lung is decreased (D).
A 76-year-old female who is a former smoker with a 30 pack-year history is admitted to the ICU with new productive cough, fevers, dyspnea, and hypoxia. She is started on high flow nasal cannula, steroids, and antibiotics with workup initiated for COPD exacerbation versus pneumonia. Her admission chest X-ray reveals a new focal lesion in the left upper lobe (LUL); follow-up CT shows a solitary tumor involving a portion of the LUL with PET scan finding no evidence of metastases. The patient’s recent pulmonary function testing demonstrates a forced expiratory volume in one second (FEV1) and diffusion capacity (DLCO) of 100%. She is being evaluated by your thoracic surgery team for possible left upper lobectomy. Using the lung segment model, what is her predicted postoperative (PPO) FEV1 and DLCO and what additional testing is necessary to further stratify her operative risk?
Correct Answer: A
It is vital to understand the role of preoperative testing and risk stratification in lung resection surgery candidates, as poor candidate selection can lead to profound morbidity and mortality. There are evidencebased guidelines to help clinicians risk stratify individual patients and pursue further testing for higher risk candidates based on PPO function. According to the American College of Chest Physicians (ACCP): “In patients with lung cancer being considered for surgery, it is recommended that both FEV1 and DLCO be measured in all patients and that both PPO FEV1 and PPO DLCO are calculated” (Brunelli et al 2013, pg. e173S).
The anatomic lung segment model divides the lungs into 19 total segments; the left upper and left lower lobe each respectively contain 5 and 4 segments while the right upper, middle, and lower lobes respectively contain 3, 2, and 5 segments. To calculate the PPO FEV1 or DLCO, first determine the percent reduction in lung volume; in your patient, a left upper lobectomy would eliminate 5 of the 19 segments, or roughly 25% (5/19 = 0.26). Therefore, the new FEV1 (or DLCO) would be:
According to ACCP Guidelines, “In patients with lung cancer being considered for surgery, if both PPO FEV1 and PPO DLCO are >60% predicted, no further tests are recommended” (Brunelli et al 2013, pg e175S). For those whose ppo-FEV1 and/or ppo-DLCO is less than 60%, additional testing is required and depends on the severity of disease (see Brunelli et al 2013, pg e179S).
Reference:
A 67-year-old female with a 50 pack-year of smoking history, COPD, hypertension, and type II diabetes is admitted to the ICU following a right middle lobectomy for resection of non–small-cell adenocarcinoma. The patient has required positive pressure ventilation since her operation because of persistent hypoxemia and inadequate ventilation on pressure support. On postoperative day 5, she develops a new persistent air leak through her right-sided chest tube. Bronchoscopy confirms the presence of a bronchopleural fistula (BPF) on the right side. The ventilator repeatedly alarms for low minute ventilation (less than 0.8 L/min) despite increasing tidal volumes and RR. The latest ABG shows the following:
Blood pressure and heart rate have remained stable.
Which of the following ventilation strategies is most appropriate until surgical repair of BPF can take place?
BPF occurs when air from a lobar or segmental bronchus leaks into the pleural space. This is most commonly encountered after lung resection surgery with a frequency ranging from 4.5% to 20% after pneumonectomy and 0.5% to 1% after lobectomy.
In most cases BPF is present in the early postoperative period (<2 weeks) following lung resection. BPF should be suspected in the postoperative lung resection patient who presents with sudden onset of dyspnea, chest pain, subcutaneous emphysema, and hemodynamic instability (ie symptoms of tension pneumothorax). Symptoms may be less abrupt, however, in patients whose chest tube is still in place. In such patients, presence of persistent or new air leak may be the only presenting sign. Bronchoscopy is often used to confirm the diagnosis.
BPFs are associated with significant morbidity and a mortality that ranges from 16% to 72%. BPFs do not typically resolve spontaneously and almost always require surgical or bronchoscopic intervention. Supportive measures should be taken to maintain hemodynamic and ventilatory stability. The first intervention is insertion of a chest tube (if not already in place) on the ipsilateral side, to drain air and fluid from the pleural space. Positive pressure and PEEP should be minimized as higher airway pressures worsen air leak and may result in impairment in ventilation and gas exchange. If adequate ventilation is not achieved using minimal positive pressure and low PEEP, isolated ventilation of the contralateral lung is indicated to maintain adequate gas exchange until definitive correction of BPF can take place.
A 54-year-old female with HTN, IDDM, obesity, and postintubation tracheal stenosis underwent a 4.3 cm tracheal resection with a pedicle flap. She is extubated after the surgery and maintained with head elevation, neck flexion, voice rest, and NPO. Routine bronchoscopy reveals a small anterior separation at the anastomosis site.
Which of the following is not a risk factor for tracheal anastomosis complications?
Correct Answer: C
The most frequent indication for tracheal resection is postintubation tracheal stenosis. Other indications include tumor, idiopathic laryngotracheal stenosis, and tracheoesophageal fistula. Operative complications can be divided into anastomotic (granulation tissue, restenosis, and separation) and nonanastomotic (infection, laryngeal dysfunction, edema, post-op hoarseness, and fistula). Based on the largest case series published on postoperative outcomes from Massachusetts General Hospital from 1975 to 2003, anastomotic complications occurred in 9% of patients, with separation occurring in 4% of patients. Risk factors for anastomotic complications were identified as reoperation, diabetes, tracheal resection ≥4 cm, laryngotracheal resection, and age <18. Interestingly, neither obesity (BMI >35) or steroid use was a risk factor. The most important postoperative goal is to minimize anastomotic tension. That is accomplished by early extubation (if possible), neck flexion, minimizing coughing and vomiting, voice rest, careful swallow evaluation, and routine bronchoscopy to detect issues before occurrence of symptoms. Careful attention should be paid toward stridor, voice changes, secretions, subcutaneous air, and neck swelling. Should timely extubation be difficult, a small tracheostomy at least 2 cm distal to the anastomosis should be considered.
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