Anesthetic considerations in the patients of chronic obstructive pulmonary disease undergoing laparoscopic surgeries.

The aim of this study was to review the various anesthetic options which can be considered for laparoscopic surgeries in the patients with the chronic obstructive pulmonary disease. The literature search was performed in the Google, PubMed, and Medscape using key words "analgesia, anesthesia, general, laparoscopy, lung diseases, obstructive." More than thirty-five free full articles and books published from the year 1994 to 2014 were retrieved and studied. Retrospective data observed from various studies and case reports showed regional anesthesia (RA) to be valid and safer option in the patients who are not good candidates of general anesthesia like patients having obstructive pulmonary diseases. It showed better postoperative patient outcome with respect to safety, efficacy, postoperative pulmonary complications, and analgesia. So depending upon disease severity RA in various forms such as spinal anesthesia, paravertebral block, continuous epidural anesthesia, combined spinal epidural anesthesia (CSEA), and CSEA with bi-level positive airway pressure should be considered.

INTRODUCTION

With advancing technology, began the era of laparoscopic surgical techniques. First, laparoscopic cholecystectomy (LC) was performed by Dr. (Prof.) Erich Mühe in 1985.[1] Increased public awareness of this minimally invasive endoscopic surgery and its benefits in the form of diminished pain, no cosmetic disfigurement, satisfactory therapeutic results as well as quicker resumption of normal activities accelerated its acceptance so much that it has become the procedure of choice for gall stone disease. The literature search was performed in the Google, PubMed, and Medscape using key words “analgesia, anesthesia, general, laparoscopy, lung diseases, obstructive.” More than thirty-five free full articles and books published from the year 1994 to 2014 were retrieved and studied. From systematic review and meta-analysis, it has been found that the global prevalence of chronic obstructive pulmonary disease (COPD) has increased over the last few decades due to increasing sedentary life styles, smoking, and prolonged life expectancy.[2] The global prevalence of physiologically defined COPD in adults aged >40 years is approximately 9–10%. Recently, the Indian study on the epidemiology of asthma, respiratory symptoms and chronic bronchitis in adults has shown that the overall prevalence of chronic bronchitis in adults >35 years is 3.49%.[3] In 2011, 12.7 million US adults (aged 18 and over) were estimated to have COPD.[4] That's why surgeons, as well as anesthesiologists, are coping with a large number of high-risk respiratory patients, especially COPD. Performing these new endoscopic surgical procedures especially on high-risk patients with COPD, translate to new anesthetic challenges demanding changes in anesthesia techniques.

At present, most laparoscopic operations are usually performed under general anesthesia (GA). Recently, however, several large retrospective studies questioned the widely held belief that GA is the best anesthetic method for laparoscopic surgeries and suggested that regional anesthesia (RA) could also be a reasonable choice in certain settings.[5] This review explores the various anesthetic techniques which can be opted for advanced cases of COPD during laparoscopic surgeries.

PATHOPHYSIOLOGY OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE

Single physiological parameter that defines this syndrome is: Limitation of expiratory airflow.[6] It is because of the combination of small airway inflammation and parenchymal destruction. Several anatomical lesions contribute to airflow limitation, including the loss of lung elastic recoil and fibrosis and narrowing of small airways, both of which are likely to cause fixed airflow limitation.[7] It adversely affects both the ventilation/perfusion (V/Q) matching and mechanics of the respiratory muscles. In the patients with advanced COPD, the combination of V/Q mismatch decreased gas transfer and alveolar hypoventilation ultimately leads to respiratory failure. Multiple pathogenetic mechanisms contribute to the development of COPD among which the most important risk factor is cigarette smoking, which can affect the lungs by a variety of mechanisms.[8] However, recently, the role of genetic factors has also been implicated, with the finding that a genetic variant (FAM13A) is associated with the development of COPD in the COPD gene study.[9] Patients with COPD pose a challenge to the anesthetist because intraoperative and postoperative complications occur more commonly than in those without the disease and can lead to prolonged hospital stay and increased mortality.

DIAGNOSIS AND ASSESSMENT

Surgeons and anesthesiologists should have clearly defined criteria for COPD regarding the assessment of perioperative and postoperative risks, surgical outcome and postoperative ventilation requirement. Airflow limitation should be assessed according to the reduction in forced expiratory volume in 1 s (FEV1), as shown in Table 1.

Table 1

Classification of severity of airflow limitation in COPD

Providing anesthesia to severe cases of lung disease poses some challenges especially when the patients are taken up for laparoscopic surgery. An underlying knowledge of the cardiovascular and respiratory pathophysiology is of paramount importance for providing safe anesthesia in these patients because all these changes get aggravated in patients with COPD.

PATHOPHYSIOLOGICAL EFFECTS DURING LAPAROSCOPY

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. 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. 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. 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 depend on the interaction of several factors including patient positioning, neurohumoral response and the patient factors such as cardiorespiratory status, and intravascular volume. 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 in the patients undergoing LC. It also decreases heart performance (fractional shortening) but does not affect cardiac output. At IAP levels >15 mmHg, the venous return decreases leading to decreased cardiac output and hypotension. 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. Increased concentrations of CO2 and catecholamines can create tachyarrhythmias. Paroxysmal tachycardia and hypertension, followed by ventricular fibrillation, have been reported.

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

The increase in IAP reduces the femoral venous blood flow. This is due to the increased pressure on the inferior vena cava and iliac veins, which reduces venous blood flow in the lower extremities. It has also been shown to reduce the portal blood flow, which may lead to transient elevation of liver enzymes.

ANESTHETIC MANAGEMENT

Preoperative evaluation and medical optimization

Patients with COPD require a comprehensive preoperative evaluation which ideally should commence well in advance with the proposed surgical intervention to allow adequate time for additional investigation and initiation of treatment.

Preoperative evaluation

A detailed history is essential for the clinical assessment of COPD severity and should focus on exercise tolerance. In addition to the routine preoperative blood tests, the patients with COPD require an electrocardiogram to look for any evidence of right-sided heart disease or concomitant ischemic heart disease. Spirometry is useful to confirm the diagnosis and to assess the severity of COPD. A baseline arterial blood gas measurement may be useful in predicting high-risk patients, with both PaCO2 > 5.9 kPa and PaO2 < 7.9 kPa predicting a worse outcome.

Nutritional status should be routinely assessed, as patients with both high and low body mass index have increased risk. Poor nutritional status with a serum albumin level <35 mg/L is a strong predictor of postoperative pulmonary complications.[13]

Maximum benefit is obtained if smoking is stopped at least 8 weeks before surgery with some studies suggesting that cessation <8 weeks before surgery is associated with increased risk of postoperative complications.[13] Patients should be urged to seek help with this as new cessation treatment methods have resulted in greatly improved success rates. In addition to nicotine replacement therapy, varenicline, or amfebutamone are options for motivated patients, but should only be prescribed alongside behavioral support. Varenicline (Champix) is a partial agonist at the a4b2 neuronal nicotinic acetylcholine receptor and has been shown to reduce withdrawal and craving by preventing the nicotine binding to the receptor.[14]

All patients with COPD require a detailed preoperative examination, as decreased breath sounds, prolonged expiration, wheeze, and rhonchi are predictive of postoperative pulmonary complications. Preoperative wheezing warrants aggressive treatment with bronchodilators and possibly steroids before surgery. Signs of active respiratory infection such as pyrexia, purulent sputum, worsening cough, or dyspnea should be sought, and if identified, surgery should if possible, are postponed and appropriate treatment instituted.

PREOPERATIVE INTERVENTIONS

It includes incentive spirometry, chest physiotherapy, and cessation of smoking.

Conduct of anesthesia

General anesthesia

General anesthetic agents, opiates, myo- relaxants as well as mechanical ventilation are known to interfere with the respiratory system.[15] The combined effects of the supine position, GA and thoracic/abdominal incision produce an immediate decline in lung volumes with atelectasis formation in the most dependent parts of the lung.[16] Moreover, the residual neuromuscular blockade persisting after anesthesia emergence has been incriminated in deficient coughing depressed hypoxic ventilatory drive and “silent” inhalation of gastric contents.[17] GA exceeding 2.5–4 h has been identified as a strong predictor of PPCs.[1819] Upper airway instrumentation (e.g., tracheal intubation) and inhalation of irritants (e.g., desflurane, external disinfectants) may trigger vagally-mediated reflex bronchoconstriction thereby promoting the expiratory collapse of the peripheral airways with incomplete lung alveolar emptying.[2021] A patient with COPD requiring a general anesthetic is likely to be at a risk of hemodynamic compromise on induction of anesthesia and initiation of intermittent positive pressure ventilation (IPPV). Placement of an arterial catheter should be considered for both beat-to-beat blood pressure monitoring and for repeated blood gas analysis. The patients in major surgeries with severe COPD and hypoxia, continuous positive airway pressure during induction may be used to improve the efficacy of preoxygenation and to reduce the development of atelectasis.

Mechanical ventilation

Most of the difficulties encountered when anesthetizing patients with COPD can be explained by the occurrence of increased intrathoracic pressure when using IPPV. Limited expiratory flow rate because of airway narrowing results in the next inhalation occurring before the expiration of the previous breath is complete, and leads to “breath stacking” or “air trapping” and the development of intrinsic positive end-expiratory pressure (PEEPi). The elevation of intrathoracic pressure results in decreased systemic venous return and may be transmitted to the pulmonary artery, raising pulmonary vascular resistance and leading to right heart strain. Other potential harmful effects of air trapping include pulmonary barotraumas or volutrauma, hypercapnia, and acidosis. When considering ways to reduce the harmful effects of air trapping, there are three approaches to consider:

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.

Before extubation, it is important to optimize the patient's condition. The neuromuscular blocking agent should be fully reversed, and 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.[14]

Hypoventilation as a result of residual anesthesia or opioids should be avoided as this may lead to hypercarbia and hypoxia.

Regional anesthesia

It includes spinal anesthesia,[22] 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.[242526]

A study was conducted by Gramatica et al. to support this evidence of using RA in laparoscopic surgeries in advanced COPD cases and showed that patients remained stable during the procedure with minimal postoperative pain and quicker recovery. The risk of increasing CO2 partial pressure can be lowered by adequately oxygenating the patient.[27]

Pursnani et al. in 1998 published a study in which it was concluded that LC can be performed safely under epidural anesthesia in patients with severe COPD. Intraoperative shoulder tip or abdominal pain does not seem to be a major deterrent and can be effectively controlled with small doses of opioid analgesia.[28]

Another case study was done in a known case of COPD patient who presented with gall stones and was scheduled for LC. In this study, the role of the combination of BiPAP and CSEA was found to be effective in high-risk cases scheduled for LC having multiple diseases including poor respiratory reserves due to severe COPD. 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]

One more case report was published by van Zundert et al. in 2006 showing the role of CSEA technique in the lower thoracic region for performing LC in a patient with severely abnormal respiratory function.[30] A study was published in 2007 by Kim et al. where LC was performed successfully under RA in patients with the severe respiratory disease and was found to be a safe alternative to GA.[31] A case report was published in 2009 by Yi et al. In their study 70-year-old male with the previous history of pneumonectomy, moderate obstructive and restrictive pattern on PFT and hypokinesia of apical anterior and septum segments on echocardiography underwent LC under segmental spinal anesthesia. Successful experience with segmental spinal anesthesia was reported in the patients with cardiopulmonary problems undergoing LC.[32] In 2014, Theodorou et al. published a case report to demonstrate the efficacy and safety of continuous spinal anesthesia (CSA) in an elderly patient with severe COPD, who was scheduled for elective LC. It was found that CSA can be used to provide a sufficient block in order to allow LC to be performed even in patients with severely abnormal respiratory function.[33]

POSTOPERATIVE MANAGEMENT

Prophylaxis against the development of postoperative pulmonary complications is based on maintaining adequate lung volume especially FRC and facilitating an effective cough. Lung expansion maneuvers such as deep breathing exercise, incentive spirometry, chest physiotherapy, and positive pressure breathing techniques prevent postoperative pulmonary complications in high-risk patients. Postoperative mechanical ventilation may be required.

ANALGESIA

Effective analgesia is a significant determinant of postoperative pulmonary function. Regional anesthetic techniques and patient-controlled rather than “on demand” drug regimen are gaining attention in modern analgesic strategies. The effectiveness of pain control can be further increased by the combination of different analgesic agents (opioids, paracetamol, and nonsteroidal anti-inflammatory drugs) while drug-related side-effects are minimized (sedation, respiratory depression, nausea, and vomiting).[3435] Epidural analgesia is a particularly attractive option as it reduces the risk of respiratory failure because of excessive sedation from opioids. It should, therefore, be considered if appropriate to the surgical procedure.

Limitations

There is a paucity of data in the literature on the laparoscopic procedures being performed under RA in patients with coexisting pulmonary disease who are deemed high-risk for GA. There are still concerns about safety and efficacy of regional techniques in these patients. Each case should be evaluated independently with regard to relative risks and a better cost-benefit ratio.

CONCLUSION

It has been concluded from above discussion that LC is not only feasible under RA but should be considered as a valid option for the patients who are poor candidates for GA like patients with advanced COPD as there is avoidance of the strong stimulation of intubation or the risk of bronchoconstriction on extubation, less risk of atelectasis, closing capacity, and FRC are less affected, pulmonary gas exchange is better maintained and it provides superior postoperative analgesia without risking respiratory depression, and so decreases the need for postoperative mechanical ventilation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest