Case 14: Pneumonectomy in patient with Advanced COPD

Question 1

What are the recommendations for pre-operative cardiac evaluation with thransthoracic echocardiography?

Answer 1

2014 American College of Cardiology Guidelines. It is recommended that patients with clinically suspected moderate or greater degrees of valvular stenosis or regurgitation undergo preoperative electrocardiography if there has been

1) no prior echo within 1 year
2) a significant change in clinical status or physical exam since last exam ie. dyspnea of unknown origin; heartfailure w/ worsening dyspnea, -

- Routine preoperative evaluation of LV function is Not reccommended –

Question 2

Describe some factors to consider when assessing cardiac risk

Answer 2

Patient-related factors  Age  Chronic disease (e.g., coronary artery disease, diabetes mellitus, or hypertension)  Functional status  Medical history  Implantable devices  Previous surgeries Surgery-related factors  Type of surgery (e.g., vascular, endoscopic, or abdominal)  Urgency status (e.g., emergency, urgent, or elective)  Surgical duration, possibility of blood loss and fluid shifts Test-related factors  Sensitivity and specificity of a test  Effect on management

Question 3

Describe the classification of severity of airflow limitations in COPD during PFT

Answer 3

Airflow limitation should be assessed according to the reduction in forced expiratory volume in 1 s

Question 4

Describe some pathophysiological effects that occur during laparoscopy?

Answer 4

Pulmonary Changes

1. In physiological effects of pneumoperitoneum, carbon dioxide is shown to be affected by raising the intra-abdominal pressure (IAP) above the venous pressure which prevents CO2 resorption leading to hypercapnia.
2. Respiratory effects include the changes in pulmonary function during the laparoscopic surgery in the form of a reduction in lung volumes, decrease in pulmonary compliance and increase in peak airflow pressure.
3. Increased IAP shifts the diaphragm cephalad and reduces diaphragmatic excursion, resulting in the early closure of smaller airways, leading to intraoperative atelectasis with a decrease in functional residual capacity.
4. Additionally, the upward displacement of diaphragm leads to the preferential ventilation of nondependent parts of lungs, which results in ventilation-perfusion (V/Q) mismatch with a higher degree of intrapulmonary shunting.

Cardiovascular Changes

1. The principal responses are an increase in systemic vascular resistance, mean arterial blood pressure and myocardial filling pressures with little change in heart rate. CO2 pneumoperitoneum is associated with the increased preload and afterload
2. At IAP levels >15 mmHg, the venous return decreases leading to decreased cardiac output and hypotension.
3. Bradyarrhythmias are attributed to vagal stimulation caused by insertion of the needle or the trocar, peritoneal stretch, or carbon dioxide embolization. These may induce cardiovascular collapse during laparoscopy even in the healthy patients.
4. Increased concentrations of CO2 and catecholamines can create tachyarrhythmias.

Neurologic Changes

1. Increases in IAP, cardiovascular responses to peritoneal insufflation, changes in the patient positioning and alterations in CO2 concentration can alter intracranial pressure and cerebral perfusion.

Renal Changes

1. Pneumoperitoneum reduces renal cortical and medullary blood flow with an associated reduction in glomerular filtration rate, urinary output and creatinine clearance.

Question 5

Maximum benefit is obtained if smoking is stopped atleast how long before surgery?

Answer 5

8 WEEKS

Question 6

Mechanical Ventilation Goals when anesthetizing patients with severe COPD?

Answer 6

• Allowing more time for exhalation. Reducing the respiratory rate or the inhalation: Exhalation ratio (typically to 1:3–1:5) allows more time for exhalation thus reducing the likelihood of breath stacking
• Application of PEEP. The use of external PEEP in ventilated patients with COPD has theoretical benefits by keeping small airways open during late exhalation, so potentially reducing PEEPi
• Treatment of bronchospasm. It should be treated promptly either by inhaled bronchodilators or by deepening anesthesia with propofol or increased concentrations of inhalation anesthetics.

Question 8

Extubation goals for patients with advanced COPD

Answer 8

Before extubation, it is important to optimize the patient’s condition.

• The neuromuscular blocking agent should be fully reversed,
• the patient should be kept warm
• Well oxygenated with a PaCO2 close to the normal preoperative value for the patient.
• Peri-extubation bronchodilator treatment may be helpful.
• Extubation of the high-risk patient directly to noninvasive ventilation may reduce the work of breathing and air trapping and has been shown to reduce the need for reintubation in the postoperative period after major surgery

Question 9

Regional Anesthesia Considerations in Patient with Advanced COPD undergoing major surgery

Answer 9

includes spinal anesthesia,paravertebral block, continuous epidural anesthesia, combined spinal epidural anesthesia (CSEA), CSEA with bi-level positive airway pressure (BiPAP).

It is accepted that GA, and, in particular, tracheal intubation and IPPV, is associated with adverse outcomes in the patients with advanced COPD. Such patients are prone to laryngospasm, bronchospasm, cardiovascular instability, barotraumas, and hypoxemia and have increased the rate of postoperative pulmonary complications

• There is now increasing evidence to support the use of regional techniques in cases traditionally thought possible only under GA.
  
  • ​Respiratory function is not affected by giving spinal and epidural anesthesia at lumbar level, except in morbidly obese patients where the neuraxial blockade has been shown to produce a 20–25% fall in expiratory functional volume (FEV1, forced vital capacity) and that may interfere with the ability to cough and to clear bronchial secretions as a result of blocking the abdominal wall muscles.[23]
  • The only limiting factor for use of spinal anesthesia in laparoscopy is patient’s discomfort with pneumoperitoneum and the associated shoulder tip pain
  • CSEA is a better option in high-risk patients because, it provides safe and effective neuraxial block than either spinal or epidural alone. BiPAP helped to maintain oxygenation when patients were sedated with propofol and were unable to maintain oxygenation with conventional methods, e.g., nasal prongs and polymask. Noninvasive ventilation and propofol sedation with spinal, epidural, and CSEA have been used and accepted as a clinically practicable method in various surgical procedures, and it helps to correct the alveolar hypoventilation.[29]

Question 10

Why would you prefer left sided double lumen tube over right sided?

Answer 10

Because the right upper lobe bronchus proximity to the carina increases the risk of right upper lobe obstruction (1-2.5 cm).

The distance from the carina to the left upper lobe is about 5 cm, providing a greater margin of safety for upper lobe occlusion.

Question 11

What is predictive postoperative FEV1 and its significance to pneumonectomy surgery?

Answer 11

• ppoFEV1 (ppoFEV1) is the predicted postoperative forced expiratory volume at one second.; Of all the spirometric exams which correlate with pulmonary complications (FVC, MVV, RV/TLC, FEV1%, ppoFEV1%), ppoFEV1 is the most predictive of pulmonary complications
• Generally, a ppoFEV1% > 40% is low-risk for respiratory complications, and ppoFEV1% < 30% is high risk
  
  • If the ppoFEV1 >40%, you can extubate in the operating room assuming the patient is alert, warm, and comfortably (AWaC)
  • if ppoFEV1 30-40, you can extubate in the OR as long as patient’s measurements of lung parenchymal function and cardiopulmonary reserve exceed the increased risk thresholds