PREOPERATIVE OPTIMIZATION IN THORACIC SURGERY

-Dr Santosh Dhakal

Moderator: Dr Shyam Krishna Maharjan

INTRODUCTIONNON-CARDIAC SURGERY• Infection• Malignancies (lungs and oesophagus)• Chest trauma• Oesophageal disease• Mediastinal tumors• Diagnostic procedures (bronchoscopy, mediastinoscopy, and

open-lung biopsies)• Tracheal resection• Lung and heart transplantation• Thoracic aortic aneurysm• Lung volume reduction• VATS ( Video assisted thoracoscopic surgery )

CARDIAC SURGERY

PREOPERATIVE EVALUATION

• Focusing on the extent and severity of pulmonary disease and cardiovascular involvement

• To determine whether the patient will be able to tolerate the planned lung resection

• Optimal pulmonary preparation

HISTORY

• Dyspnea

• Cough

• Cigarette smoking

• Exercise tolerance

• Risk factors for acute lung injury (preoperative alcohol abuse, patients undergoing pneumonectomy)

• Physical examination - Respiratory pattern: cyanosis, clubbing, breathing pattern, type of breath sounds

• Tracheal deviation, Potentially difficult intubation of the trachea, airway obstruction on induction of anaesthesia

EVALUATION OF CARDIOVASCULAR SYSTEM

• Presence of increased pulmonary vascular resistance secondary to fixed reduction in cross-sectional area of pulmonary vascular bed

• Auscultatory signs of increased PAP and PVR: a. narrowly split second heart sound, b. increased intensity of the pulmonary component of

second heart sound, c. fourth heart sound, d. high pitched early systolic ejection click

H/o angina or ECG suggestive of ischemia

Non-invasive exercise ECG testing(limited by low ventilatory or cardiac reserve)

If normal, if indicates ischemiaproceed to surgery

Thallium exercise test plan for surgery

If positive for ischemia

Coronary angiography

If negative

• If significant coronary artery disease, coronary artery bypass grafting before or at the time of pulmonary resection

• For lesser degree of CAD, preoperative appropriate medical therapy and then plan for surgery

• In cases that require large resections in compromised patients, CABG should be done first and pulmonary resection should be delayed until the patient has gained weight and muscle mass (usually 4 to 6 weeks).

INVESTIGATIONS• Blood investigations: Hct, Hb, TC, DC, RFT, Na+, K+,

RBS• ECG - low voltage QRS complex - poor progression of R wave across the precordial leads - features of RVH

• Chest x-ray: location of lung lesion assessed by PA and lateral view

- Tracheal or carinal shift - Hyperinflated lung field - increased vascular markings - Bullae - Mediastinal mass

• Arterial blood gas analysis

• Pulmonary function tests

• Echocardiography

• CT scan chest

• Splint-lung function test

• Diffusing capacity for carbon monoxide

PULMONARY FUNCTION TESTING

• To identify the patient at risk of increased postoperative morbidity and mortality

• To identify the patient who will need short-term or long-term postoperative ventilatory support

• To evaluate the beneficial effect and reversibility of airway obstruction with the use of brochodilators

SPIROMETRY

• An abnormal vital capacity: 33% likelihood of complications and 10% risk of postoperative mortality

• FEV1: a more direct indication of airway obstruction

• Ratio FEV1/FVC

• Maximum voluntary ventilation (MVV): < 50% of predicted value – high risk

• Ratio of RV/TLC: > 50% of predicted value – usually indicative for high risk patient for pulmonary resection

• Predicted postoperative FEV1 value: Preoperative FEV1 x (1- % functional lung tissue removed/100)

if < 30%: increased risk for postoperative pulmonary complications, more likely to need postoperative ventilation

• Significance of bronchodilator therapy: for assessment of the degree of airways obstruction and the patient’s effort ability

- A 15% improvement in PFTs may be considered a positive response to bronchodilator therapy

Preoperative FEV1 = 70% of predicted

Postoperative FEV1 = 70 x (1 – 29/100)

= 50%

FLOW-VOLUME LOOPS

SPLINT-LUNG FUNCTION TEST• To predict the function of the lung tissue that would

remain after lung resection• Regional perfusion test• Regional ventilation test

CT scan chest• Provide anatomic sections through the chest• Can delineate the size of the airway• Reveals if there is airway or cardiovascular compression

Diffusing capacity for Carbon monoxide• Reflects ability of the lung to perform gas

exchange

• A predicted postoperative diffusing capacity for carbon monoxide <40% is associated increased risk

• Predicted postoperative diffusing capacity percent is the strongest single predictor of risk of complications and mortality after lung resection

MAXIMAL OXYGEN CONSUMPTION• A predictor of postoperative complications

• Patients with a VO2 max > 15 to 20 ml/kg/min are at reduced risk

• A VO2 max < 10 ml/kg/min indicates very high risk for lung resection

• Exercise oximetry: a decrease of 4 % during exercise is associated with increased risk

• A 6 minute walk test

IMPORTANCE OF PREOPERATIVE OPTIMIZATION

• High risk for postoperative pulmonary complications –

- positively correlate with the degree of preoperative respiratory dysfunction

- impairment of lung function due to performance of surgery

- resistance to deep breathing and coughing secondary to painful incision

• Preoperative preparation efforts for managing any preexisting pulmonary disease.

• Elements of the preoperative regimen:

1) Stopping smoking,

2) Dilating the airways,

3) Loosening secretions

4) Removing secretions

5) Adjunct medication

6) Increased education, motivation, and facilitation of postoperative care

1) Stop smoking, avoid industrial pollutants (if able to)

- cessation of smoking for more than 4 to 8 weeks associated with a decrease in the incidence of postoperative respiratory complications

Beneficial effects of smoking cessation and time course

Time course Beneficial effects12 – 24 hrs Decreased CO and nicotine levels48 – 72 hrs COHb levels normalized, ciliary function improves1 – 2 wk Decreased sputum production4 – 6 wk PFTs improve6 – 8 wk Immune function and metabolism normalizes8 – 12 wk Decreased overall postoperative morbidity and

mortality

2) Dilate airways

a. Beta2 – agonists b. Ipratropium bromide- especially if severe

COPD c. Methylxanthines d. Inhaled steroids (systemic steroids – when

bronchospasm is severe)

3) Loosen secretions a. Airway hydration (humidifier/nebulizer) b. Systemic hydration c. Mucolytic and expectorant drugs

4) Remove secretions a. Postural drainage b. Coughing c. Chest physiotherapy (percussion and vibration)

• Relative contraindications of chest physiotherapy:

a) lung abscesses

b) metastases to the ribs

c) a history of significant hemoptysis

d) inability to tolerate the postural drainage positions

5) Adjunct medication a. Antibodies – if purulent sputum/bronchitis b. Antacids, H2 blockers, or PPIs – if symptomatic reflux

6) Increased education, motivation, and facilitation of postoperative care

a. Psychological preparation b. Preoperative pulmonary care training 1. Incentive spirometry 2. Secretion removal maneuvers c. Preoperative exercise d. Weight loss/gain e. Stabilize other medical problems

• Lung expansion maneuver:

- deep breathing exercise and use of incentive spirometry

- critical for limiting postoperative morbidity related to atelectasis and pneumonia

- preoperative preparation better than delaying until after the surgery

• Preoperative prophylaxis against atrial flutter/fibrillation - approx. 25% of patients

- etiology: poorly understood, may be due to manipulation of heart, reduction in available vascular bed for perfusion after resection of pulmonary tissue

- 60 years or older : most consistent independent preoperative risk factor

- Digoxin, calcium channel blocker

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