pre-operative pulmonary evaluation

Pre-operative Pulmonary Evaluation

Ri 傅莉芬 /VS郭順文

Pulmonary Complications• Infection (Pneumonia or bronchitis)• Atelectasis• Respiratory failure and prolonged mechanical

ventilation• Bronchospasm• Exacebation of underlying chronic lung

disease

→↑ hospital day, ↑ morbidity & mortality

• Benefits from surgery ←→ Risk of complications

Outline

• Patient related risk factors

• Procedure related risk factors

• Preoperative risk assessment

• Risk reduction strategies

Patient related risk factors

• Age

• Obesity

• Smoking

• General health status

• Chronic obstructive pulmonary disease (COPD)

• Asthma

Age

• Minor risk factor

• independent predictor (?)

• ASA risk class 3 or 4, and advanced age(>50yr) independent risk factors

• Surgery should not be declined in elderly patients who are otherwise acceptable surgical candidates.

Obesity• Morbid obesity → restrictive lung disease,↓

thoracic compliance, alveolar hypoventilation• Not consistent

– 169 patients treated for acetabular fracture,

• obese subjects (BMI ≥ 30) > normal weight (BMI <25)

– 10 series of obese gastric bypass,

• morbidly obese patients(3.9%)≒ non-obese patients.8

Smoking• Important risk factor• Smoking history of 40 pack years or more

→↑risk of pulmonary complications• stopped smoking < 2 months : stopped for > 2

months = 4:1 (57% : 14.5%) • quit smoking > 6 months : never smoked =

1:1 (11% : 11.9%)

General health status

• American Society of Anesthesiologists classification

• Goldman cardiac risk index – include factors from history, physical

examination and laboratory data

COPD• P’t with severe COPD

– 6 times more likely to have major postoperative pul. Complication

• an absolute contraindication is NOT apparent• A careful preoperative evaluation of patients

with COPD – identification of high-risk patients – optimizing their treatment before surgery.

Asthma• Inadequate control of asthma →↑risk of

postoperative complications• Well controlled, peak flow measurement

of >80% of predicted or personal best → average risk

• Asthmatic patients treated with corticosteroids before surgery have a low incidence of complications

Procedure related risk factors

• Surgical site

• Size of removed lung parenchyma

• Duration and type of anesthesia

• Type of neuromuscular blockade

Surgical site• the most important predictor of

pulmonary complications• The incidence of complications is

inversely related to the distance of the surgical incision from the diaphragm

• The complication rates for upper abdominal and thoracic surgery are the highest (range 10% to 40%)

Surgical site (cont.)

• Upper abdomen– Incisions cross the abd. muscle,↓

diaphragmatic motility → ↓Vital capacity

• Lateral thoracotomy– Incision of the intercostal muscle,

introduction of a pleural drain → pleural effusion, post-op pain → ↓ thoracic compliance


• Thoractomy– Without pulmonary disease

• VC ↓ to 60~70% of the pre-operative value• Recovering the baseline value from one to two

weeks, even if the restrictive defect can last longer, if thoracic pain persists

Surgical site (cont.)– With pulmonary disease

• The effects of thoracotomy are amplified by the coexistence of a pulmonary disease

• Thoractomy → thoracic pain → ↓deep breathing, effective coughing → atelectasis, bronchial mucous retention, worsening of gas exchange

Surgical site (cont.)• Video-assisted thoracoscopic surgery (VATS)

– reduced pain, postoperative complications, release and responses of proinflammatory cytokines, and better ventilatory function during very early postoperative period after lung resection than standard thoracotomy

– same or better prognosis with a lesser resection by extended segmentectomy or wedge resection with VATS in patients with small lung cancer has been recently published

– VATS lobectomy in NSCLC at clinical stage I could well be acceptable

• VATS lobectomy for Stage I lung cancer, with 97.2% 8-year survival rate for Stage IA lung cancer, better than outcomes by thoracotomy

• VATS lobectomy for lung cancer has the benefits of less pain, shorter hospital stay, less inflammatory response and better long term functional level (extremity movement)

– It suggests that these procedures would be applied for patients with poor pulmonary reserve who have not been considered as candidates for pulmonary resection.


• Lung biopsy through small thoracotomy– Minimal incision, very small resected lung

parenchyma– Rare respiratory effects– Few contraindications (eg. Hemodynamic

instability, serious haemocoagulative alterations)


• Heart-surgery – usually require median sternotomy– functionally better tolerated than lateral

thoracotomy (due to preserves the pleural space)

– respiratory function is generally well preserved, except for a transitory reduction in pulmonary volumes.

Size of removed lung parenchyma

• Removal of non-functional lung– Bulla

• may cause an improvement or at least no deterioration in lung function

– Bronchiectasis• ↓secretions and purulent exudates

– Benign tumor (ex. thickened pleura decortication)

• may allow the remaining lung to re-expand

Size of removed lung parenchyma (cont.)

• However, in most patients, thoracic surgery results in some function impairment

• Lobectomy shows less functional consequences than pneumonectomy


• Lobectomy– the remaining lobes on that side rapidly

expand to fill the vacant space– only a modest reduction in VC, in Maximal

Voluntary Ventilation (MVV) and in the DLCO occur

– After surgery, the adaptation of the remaining lobe may take up to three months


– The entity of the functional reduction depends on the removed lobe

• lobectomy of the right middle lobe (2 segments) has a smaller functional impact than the lobectomy of the right inferior lobe (5 segments)

Size of removal of removed lung parenchyma (cont.)

• Pneumonectomy– Space remains is partly filled by

mediastinal displacement and ascent of the diaphragm

– Pleural fluid usually collects and replaces the pneumothorax


– Inspite of this, ventilatory capacity after pneumonectomy may be surprisingly good

– If the parenchyma of the remaining lung is normal, blood gases remain in the normal range both at rest and during exertion

– Only pulmonary arterial pressure, which is normal at rest, may increase during exertion

Duration and type of anaesthesia

• Anesthesia time of > 3.5 hours →↑incidence of pulmonary complications

• in a very high risk patient→ a less ambitious, briefer procedure

Duration and type of anaesthesia (cont.)

• a review of high risk p’t– rate of respiratory failure

• general anesthesia > epidural analgesia and light anesthesia


• The review evaluated the results of 141 trials that included 9559 p’t – a reduction in risk of pulmonary complications

among patients receiving neuraxial blockade (either epidural or spinal anesthesia) with or without general anesthesia, when compared to those receiving general anesthesia alone

– neuraxial blockade• ↓39 ％ risk of pneumonia, ↓59％ risk of

respiratory depression


• it appears likely that general anesthesia leads to a higher risk of clinically important pulmonary complications than do epidural or spinal anesthesia, although further studies are required to confirm this

Type of neuromuscular blockade

• Pancuronium, a long-acting neuromuscular blocker– a higher incidence of postoperative

residual neuromuscular blockade – a higher incidence of postoperative

pulmonary complications in those patients with residual neuromuscular blockade

Preoperative risk assessment

• Resective thoracic surgery

• Extra-thoracic and thoracic surgery without lung resection

Resective thoracic surgery

• Clinical evaluation– History & PE

• Pulmonary function test– Spirometry & Blood gas analysis

• Split lung function studies

• Cardopulmonary exercise test

Clinical evaluation• Complete history

– Smoking, poor exercise tolerance, unexplained dyspnea or cough

– unrecognized chronic lung disease should be determined

• Good physical examination– directed toward evidence for obstructive lung

disease– decreased breath sounds, wheezes, rhonchi, or

prolonged expiratory phase

Pulmonary function testing• all candidates for lung resection should

have preoperative PFT • PFTs should not be ordered routinely prior to

abdominal surgery or other high risk surgeries– Patients undergoing coronary bypass or upper

abdominal surgery with a history of smoking or dyspnea.

– Patients undergoing head and neck, orthopedic, or lower abdominal surgery with unexplained dyspnea or pulmonary symptoms

Pulmonary function testing(cont.)

• These tests simply confirm the clinical impression of disease severity in most cases, adding little to the clinical estimation of risk

• There has also been concern that preoperative PFTs are overused and a source of wasted health care dollars


• PFTs should not be used as the primary factor to deny surgery

• the results from PFT should be interpreted in context of clinical situation and should not be the sole reason to withhold necessary surgery

• Most patients with abnormal spirometry would be apparent based on history and physical examination


• Two reasonable goals to use of preoperative PFTs– Identification of a group of patients for whom the

risk of the proposed surgery is not justified by the benefit

– Identification of a subset of patients at higher risk for whom aggressive perioperative management is warranted


• Spirometry– performed when the patient is clinically stable and

receiving maximal bronchodilator therapy– Risky for Pneumonectomy

• FEV1< 60% of the predicted value or < 2 liters • DLCO< 60% of the predicted value • MVV< 50% of the predicted value

– Safe lower limit for Pneumonectomy• FEV1> 80% of the predicted value or > 2 liters

– Safe lower limit for Lobectomy• FEV1>1.5 litres or > 60% of the predicted value


• Blood gas analysis– Current data do not support the use of

preoperative arterial blood gas analyses to stratify risk for postoperative pulmonary complications

– Hypoxemia: SaO2 < 90%– Hypercapnia: PaCO2 > 45mmHg

• not necessarily an absolute contraindication for surgery• lead to a reassessment of the indication for the proposed

procedure and aggressive preoperative preparation


At-risk p’t require a closer diagnostic examination toestimate the likely post-resection pulmonary reserve

Split lung function studies• Predicting post-resection pulmonary function• Predicted postoperative FEV1 (ppoFEV1) is

the most valid single test available– ppoFEV1 = preoperative FEV1 × (1– %functional

tissue removed/100)– lung function can be calculated by counting the

number of segments removed • The lungs contain 19 segments (3 right upper lobes, 2

right middle lobes, 5 right lower lobes, 3 left upper lobes, 4 left lower lobes, 2 left lingula)

Split lung function studies(cont.)

– Ventilation-perfusion(V/Q) scan• allows detailed assessment of the functional capacity of

the lung and accurate determination of which lobes or segments contribute proportionally to ventilation and perfusion before their resection

• Allows the calculation of the functional remaining parenchyma after surgery and the predicted post-resection FEV1 value

• Correlations between the predicted and observed post-resection FEV1 values have proved to be good, although errors tend to underestimate postoperative function

– Quantitatve CT

Split lung function studies(cont.)

• FEV1ppo > 40%, DLco ppo > 40%– Widely accepted as a predictor of average risk for

complications

• FEV1ppo < 40%, DLco ppo < 40%– High risk of perioperative complications including

death– FEV1ppo <1L → sputum retention– FEV1ppo <0.8L → preclude resection , dependent on

a ventilator

• Post-operative lung function shows borderline values → Cardiopulmonary exercise test

Cardiopulmonary exercise test

• stress the entire cardiopulmonary and oxygen delivery system → expect the functional reserve after pulmonary resection

• Maximal oxygen uptake (VO2max)– VO2max > 20mL/kg/min

• are not at increased risk for complications or death

– VO2max < 15 mL/kg/min • an increased risk of peri-operative complications

– VO2max < 10 mL/kg/min • a very high risk for post-operative complications or death

Assessment of p’t candidate for lung resection

A Case of lung resection

Admission

• Chief Complaint– One mass over right paratracheal area was

accidentally found by Chest X-ray

• Diagnosis – Lung cancer

• VATS lobectomy, RUL and LN dissection

• Present Illness– 林 X 雲 , 63-year-old woman– Histories of COPD, angina, peptic ulcer

and renal stone– Cigarette smoking for more than 40 yrs

and got COPD since youth– Since 4 years ago

• Cough with whitish sputum and dyspnea with dizziness while suddenly standing and exercise

– Regular follow-up and took medicine for COPD and angina every month at 苗栗弘大 hospital

– Follow up chest X ray in 96/08• Right paratracheal lesion • CEA: 7.5

– Body weight loss from 38 kg to 34 kg in 2 months

– She was admitted for further survey and managements

• Past History– Major systemic disease

• COPD, angina, peptic ulcer, renal stone, DM(-), HTN(-)

– Operation• Appendectomy, C/S, hysterectomy for myoma,

cataract

– Drug allergy: pyrine– Drinking(-); Smoking(+): <1PPD for 40 yrs

• 96/11/13– PFT

• FVC: 1.92L; % of predict: 93.1%• FEV1: 0.78L; % of predict: 47.7%• FEV1/FVC: 40.6%<60%→airflow obstruction

• 96/11/16– CT-guided biopsy

• Lung cancer, Squamous cell carcinoma

• 96/11/19– Bone scan: negative

• 96/11/22– Exercise PFT

• VO2(ml/min/Kg):61.89%• Discontinued due to weakness and dyspnea

– Whole body PET• Solitary FDG hypermetabolic lesion at RUL

• 96/11/26– VATS lobectomy,RUL and LN dissection– Hemodynamic calculation

• PVR: 749 DS/cm5

ICU Treatment Course• 96/11/27

– Cardiac echo• Good LV contractility, LVEF: 84.6%• TR(+): moderate with PG 25 mmHg• CVP: 11~12• PAP:47/22(32)------Pulmonary Hypertension!• ABP:87/52(66)

– After PGE1 use• PVR: 491 DS/cm5

– Try weaning gradually– Chest tube: -10cm H2O low pressure

• 96/11/30– Right lung pneumonia– Change Cefametazon to Tazocin for

pulmonary infiltration increase– CRP: 8.15– Off PGE1– Remove S-G( 留 sheeth)

Risk reduction strategies

• Pre-operative strategies

• Intra-operative strategies

• Post-operative strategies

Pre-operative strategies

• goals of preoperation pulmonary evaluation– identify high-risk patients in whom

prophylactic measures may reduce the risk of postoperative complications

Pre-operative strategies(cont.)

• Smoking cessation– As least 8 weeks before surgery– Counseling accompanied with nicotine

replacement or bupropion therapy improves the success rate

• COPD– be treated aggressively to achieve their

best possible baseline function – Bronchodilators, smoking cessation,

antibiotics, and chest physical therapy– give preoperative course of systemic

steroids to patients who continue to have symptoms despite bronchodilator therapy.

• Asthma– an evaluation before surgery

• a review of symptoms, medication use (particularly the use of systemic corticosteroids for longer than 2 weeks in the past 6 months), and measurement of pulmonary function.

– A short course of systemic corticosteroids may be necessary to optimize pulmonary function.

– For patients who have received systemic corticosteroids during the past 6 months

• give 100 mg hydrocortisone every 8 hours intravenously during the surgical period and reduce dose rapidly within 24 hours following surgery

• Pre-operative antibiotics– Treat respiratory infection if present– Indiscriminate use of prophylactic

antibiotics does not lead to a reduction in pulmonary complications and should be avoided

• Patient education– Lung expansion, deep breathing and

coughing

Intra-operative strategies

• Type of anesthesia– Intermediate and shorter acting agents are

preferred– Spinal anesthesia is safer than general

anesthesia for high-risk patients

• Duration and type of surgery– a less ambitious, shorter procedure should

be considered in high-risk patients.– Because upper abdominal and thoracic

operations carry the greatest risk, a laparoscopic procedure should be preferred over an open procedure if possible.

Post-operative strategies• Lung expansion maneuvers

– Deep breathing exercises, incentive spirometry

• ↓postoperative pulmonary complications in high-risk patients

– Postoperative continuous positive airway pressure (CPAP)

• ↓the incidence of pulmonary complications after major abdominal surgery

• Pain control– helps minimize pulmonary complications

• encouraging early ambulation, performance of lung expansion maneuvers.

– opioid narcotics and related medications • Intrathecal: longer duration of analgesia (15-22

h) but may be associated with respiratory depression and headaches

• Epidural: an alternative to systemic analgesia

Thanks for your listening!

pre-operative pulmonary evaluation

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