Anesthesia: A Topical Update – Thoracic, Cardiac, Neuro, ICU, and Interesting Cases

Amballur D. John

• Publisher: Bentham Science Publishers
• Year: 2018
• ISBN:
  9781681087238
• Topic: Médecine
• Subtopic: Anesthésiologie et gestion de la douleur

This book provides an updated information about major systems for anesthesia in patients with concomitant diseases. Book chapters are designed to allow anesthesia providers to refresh their knowledge, and be able to focus on the current issues in these su

Thoracic Anesthesia

Chandrika R. Garner, Adair Q. Locke, Thomas F. Slaughter^*

Wake Forest School of Medicine, Winston Salem, North Carolina, USA

Abstract

Given a higher prevalence of smoking, pulmonary and cardiovascular disease, and in many cases carcinoma, thoracic surgical patients experience a higher risk for perioperative morbidity and mortality than that of broader surgical populations. Careful preoperative assessment of functional status and a focus on optimizing preexisting conditions prove critical to successful surgical outcomes. As open thoracotomies decline in number, minimally invasive surgeries – including video assisted thoracoscopy (VAT) and robotic surgical approaches pose new challenges for intraoperative anesthetic management. Although double lumen endotracheal tubes remain the most common approach to lung isolation, an array of newer endobronchial blockers provide opportunities to facilitate surgery in patients with difficult airways as well as those requiring lobar isolation to tolerate surgical resection. Surgery of the esophagus and trachea continue to pose enormous challenges to both our intraoperative management and postoperative care. In thoracic surgery, perhaps more so than any other field, there is no doubt that anesthetic interventions in the preoperative, intraoperative, and postoperative settings directly impact patient survival and recovery. Evolving surgical techniques – particularly the move toward less invasive surgery – will challenge our current dogma pertaining to anesthetic management of the thoracic surgical patient – necessitating outcomes based research to further reduce adverse perioperative outcomes and enhance surgical recovery.

Keywords: Bronchial Blocker, Bronchoscopy, Double Lumen Tube, Esophagectomy, Hypoxemia, Lung Cancer, Mediastinoscopy, Non-small Cell Lung Cancer, One Lung Ventilation, Paravertebral Block, Small Cell Lung Cancer, Spirometry, Thoracotomy, Thoracic Anesthesia, Thoracic Epidural, Tracheal Resection, Tracheal Stenosis, Univent, VAT’s.

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^* Corresponding author Thomas F. Slaughter: Wake Forest School of Medicine, Winston Salem, North Carolina, USA; Tel: [phone]; E-mail: [email protected]

INTRODUCTION

As a population, thoracic surgical patients experience at least moderate risk for perioperative morbidity and mortality. In many cases, these patients undergo pulmonary resections for cancer with underlying lung disease due to smoking and

other comorbidities. Patients undergoing thoracic surgery experience post- operative pulmonary and cardiac complications at rates exceeding that of the general surgical population. In addition to benefits afforded by any preoperative evaluation, this assessment serves 2 major purposes before thoracic surgery. First, a directed history and physical examination with targeted laboratory testing afford an opportunity to identify patients at increased risk for postoperative morbidity and mortality such that resources may be directed to mitigate risk. A secondary goal would be to identify patients most likely to require mechanical ventilatory support in the postoperative period – at least short term [1, 2]. In the case of most forms of lung cancer, mortality rates in the absence of surgery prove so dismal as to encourage fairly liberal criteria when assessing suitability for pulmonary resection. Increasing use of minimally invasive surgical procedures, lung sparing surgery, and postoperative pain management (including thoracic epidural analgesia) have extended the population eligible for surgery [3]. However, both patient and surgical team should be aware of the risks as well as potential for impaired quality of life after surgery. Not infrequently, surgical plans change on entry to the chest. A minimally invasive wedge resection may progress to pneumonectomy to offer the best chance for a cure. An understanding of the patient’s underlying medical conditions – and ventilatory reserve in particular– proves crucial to team decisions about the course of action offering the greatest chance for recovery and a meaningful quality of life [4].

PREOPERATIVE CONSIDERATIONS IN THE PATIENT WITH LUNG CANCER

Given that a majority of patients undergoing thoracic surgical procedures will do so for lung cancer consideration of these diseases and underlying anesthetic concerns merit discussion. In the U.S., lung cancer remains the leading cause of cancer related deaths exceeding that of breast, prostate, and colorectal cancers combined. Cigarette smoking has been implicated in 90% of lung cancers with additional contributions by a number of genetic and environmental factors including exposure to asbestos, radon, and industrial carcinogens [5^-10]. Although primary lung cancer may be categorized into more than 5 histologic categories, for purposes of staging and treatment bronchogenic carcinoma is categorized as either: 1) small cell lung cancer (SCLC) or 2) non-small cell lung cancer (NSCLC) [11^-14] (Table 1).

In most cases, micrometastatic disease is present at the time of diagnosis of SCLC, meaning that most often this disease process does not prove amenable to surgical resection. In contrast, survival in NSCLC proves unlikely without surgical resection of the primary tumor [15^-17]. So, the focus of the surgical preoperative assessment is 1) to determine whether the primary tumor is resectable; and 2) to determine whether the patient is likely to tolerate the planned procedure with acceptable perioperative morbidity and mortality.

Histologic Categories of Lung Cancer

Table 1 Histologic Categories of Lung Cancer.

Histologic Category	Incidence	Source	Characteristics
Squamous cell carcinoma	20%	Bronchial epithelium	Centrally located Local spread
Adenocarcinoma	35-40%	Mucus glands	Peripheral location Early metastasis
Large cell carcinoma	3-5%	Heterogeneous	Peripheral location Early metastasis
Carcinoma unspecified	20-25%	Undifferentiated	Aggressive course
Small cell carcinoma	10-15%	Bronchial	Centrally located Early metastasis

Anesthetic considerations specific to any lung cancer include: 1) direct localized effects from the primary tumor (i.e. tracheal deviation, mediastinal or pleural extension, abscess formation, pleural effusion); 2) potential for mestastases (i.e. brain, liver, bone); 3) toxicity resulting from prior chemotherapy (i.e. doxorubicin [cardiac], cisplatin [renal], bleomycin [pulmonary]; and 4) paraneoplastic syndromes (i.e. hypercalcemia, Cushing’s syndrome, syndrome of inappropriate antidiuretic hormone [SIADH], Lambert-Eaton syndrome [1, 2, 18].

Pulmonary Function Testing

Pulmonary Function Testing Suggestive of Increased Postoperative Morbidity

All thoracic surgical patients with underlying lung disease require preoperative assessment by spirometry. Numerous measures derived from spirometry – including forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), maximal voluntary ventilation (MVV), and residual volume/total lung capacity (RV/TLC) – have been associated with adverse outcomes after surgery and pulmonary resection specifically [19^-22] (Table 2). A vital capacity (VC) 3-fold greater than tidal volume is considered necessary to generate an effective cough. Moreover, MVV less than 50% predicted has been associated with poor postoperative outcomes. Patients in otherwise good health with an FEV1 exceeding 2L are considered at low risk for either lobectomy or pneumonectomy. The most predictive spirometric test for postoperative respiratory complications may be the estimated postoperative FEV1%. Estimated postoperative FEV1% may be derived from the preoperative FEV1 after adjustment for the amount of lung to be resected – as depicted below.

Table 2 Pulmonary Function Testing Suggestive of Increased Postoperative Morbidity.

• Estimated postoperative FEV1% < 40%

• Estimated postoperative DLCO < 40%

• Maximal oxygen consumption (VO2max) < 10 ml/kg/min

• Forced vital capacity (FVC) < 50% predicted

• Forced expiratory volume in 1 sec (FEV1) < 2L

• FEV1/ FVC < 50%

• Maximum voluntary ventilation (MVV) < 50% predicted

• Res...