5 Respiratory disease

Predicting postoperative pulmonary complications 99

Assessment of respiratory function 100

Respiratory investigations 102

Postoperative care 104

Postoperative admission to HDU/ICU 106

Respiratory tract infection and elective surgery 107

Smoking 108

Asthma 110

Chronic obstructive pulmonary disease (COPD) 114

Bronchiectasis 116

Cystic fibrosis 118

Restrictive pulmonary disease 120

Sleep apnoea syndrome 122

Sarcoidosis 124

Anaesthesia after lung transplantation 125

Incidence with lower abdominal surgery is 2–5%.

Following upper abdominal or thoracic surgery, lung volume (FRC) and tidal volume fall, and coughing may be ineffective. The diaphragm moves less after abdominal surgery (vital capacity falls by 50% after open cholecystectomy, even in healthy patients).

Poor basal air entry and sputum retention often result, which may develop into atelectasis and/or infection. Effective postoperative analgesia, early mobilisation, and physiotherapy may reduce both the incidence and severity.

Complications are minimised if the underlying condition is identified and optimally controlled preoperatively.

All patients benefit from a review of their medical therapy, early mobilisation, and pre- and postoperative chest physiotherapy.

Consider review by a respiratory physician.

FRC may be reduced by 50% of awake supine value in morbidly obese patients. Positive end expiratory pressure (PEEP) may reduce these effects. FRC is relatively maintained during ketamine anaesthesia.

Under anaesthesia, closing capacity (the lung volume at which airway closure begins) encroaches upon FRC and airway closure occurs. This happens more readily in smokers, the elderly, and those with underlying lung disease.

Chest CT shows atelectasis in the dependent zones of the lungs in >80% of anaesthetised subjects. At least 10% of pulmonary blood flow is shunted or goes to areas of low V/Q ratio.

Intubation halves dead space by circumventing the upper airway.

The ventilatory response to hypercapnia is blunted and the acute responses to hypoxia and acidaemia almost abolished by anaesthetic vapours at concentrations as low as 0.1 MAC.

Most of these adverse changes are more marked in patients with lung disease but usually improve within a few hours postoperatively. After major surgery they may last several days.

Preoperative identification of patients with pre-existing respiratory dysfunction reduces postoperative complications.

Even for patients with severe pulmonary disease, surgery that does not involve the abdominal or chest cavities is inherently of very low risk for serious perioperative pulmonary complications.

Abnormal findings on examination or an abnormal CXR may reflect significant lung disease and are independent predictors of pulmonary complications.

Absence of symptoms or signs does not exclude significant pathology which will be unmasked by anaesthesia (e.g. sarcoidosis—see p. 124).

Spirometry was formerly considered highly important in the assessment of surgical patients. Recent evidence suggests that preoperative spirometry does not predict individual risk of pulmonary complications and should not be used alone to determine operability for non-thoracic surgery.

Large and rigorous studies to identify risk factors for pulmonary complications are lacking (in contrast to those identifying cardiac risk).

Increasing age (>60yr)

Chronic obstructive pulmonary disease

Smoking within 8wk of surgery

ASA grade 2 or greater

Congestive heart failure

Functional dependence

Alcohol use

Impaired consciousness

Serum albumin less than 35g/dl

Upper abdominal and thoracic surgery

Neurosurgery, head and neck surgery

Vascular surgery, especially aortic aneurysm repair

Emergency surgery

Determine patient's assessment of lung function and their compliance with treatment. Respiratory disease tends to fluctuate in severity and patients are usually best at determining their current state. Elective surgery should be performed when respiratory function is optimal.

Note cough and sputum production (character and quantity). Send a sputum specimen for culture and sensitivity.

Note past and present cigarette consumption, encouraging cessation.

Assess current treatment, reversibility of symptoms with bronchodilators, and steroid intake.

Note any respiratory symptoms suggestive of cardiac disease (orthopnoea, PND). Investigate and treat accordingly.

Dyspnoea can be described using Roizen's classification. Undiagnosed dyspnoea of grade II or worse may require further investigation (see below).

Complications of respiratory disease (e.g. right heart failure) and its treatment (e.g. steroid effects) should be sought. Try to establish any contribution of cardiac disease to respiratory symptoms.

A formal assessment of exercise tolerance such as stair climbing correlates well with pulmonary function tests and provides a reliable test of pulmonary function. However, it also reflects cardiovascular status, cooperation, and determination and is an impractical assessment for those with limited mobility.

Measured on ward using a peak flow meter (best of three attempts); technique is important. For normal values see p. 1264.

The patient's daily record gives a good indication of current fitness.

Coughing is ineffective if the peak flow is <200l/min.

Normally the forced vital capacity (FVC) is reported along with forced expiration in 1s (FEV₁), plus the ratio FEV₁/FVC (as a percentage). The results of these tests are given with normal values calculated for that individual. A normal FEV₁/FVC ratio is 70% (see p. 1264).

Previously used to assess risk in patients with significant respiratory disease scheduled for major surgery. However, recent evidence suggests that spirometry does not predict pulmonary complications, even in patients with severe COPD.

No spirometric values should be viewed as prohibitive for surgery. Despite poor preoperative spirometry, many series of patients undergoing thoracic and major non-thoracic surgery are being increasingly reported. An FEV₁ <1000ml indicates that postoperative coughing and secretion clearance will be poor and increases the likelihood of needing respiratory support following major surgery.

Specific subgroups of patients who may benefit from spirometry are:

Spirometry also forms part of the assessment of patients for lung parenchymal resection (see p. 366).

In those with an obstructive picture (low FEV₁/FVC ratio), reversibility with salbutamol should be tested. If time permits, the spirometry should be repeated after a course of steroids (prednisolone 20–40mg daily for 7d).

Peak flows at different lung volumes are recorded. Although more complex to interpret, loops provide more accurate information regarding ventilatory function. They provide useful data about the severity of obstructive and restrictive respiratory disease.

Used in assessment of airway obstruction from both extrinsic (e.g. thyroid) and intrinsic (e.g. bronchospasm) causes.

Reduced in lung fibrosis and other interstitial disease processes affecting gas transfer from alveolus to capillary.

Normal value: 17–25ml/min/mmHg.

Detects CO₂ retention. A resting PaCO₂ >6.0kPa (45mmHg) is predictive of pulmonary complications and suggests ventilatory failure.

Demonstrates usual level of oxygenation, which indicates severity of disease and is useful to set realistic parameters postoperatively.

An abnormality predicts risk of pulmonary complications.

Reveals lung pathology, cardiac size and outline, and provides a baseline should postoperative problems develop.

Impingement of mass lesions on the major airways and likely extent of lung resection can be assessed.

May demonstrate anterior or posterior pneumothorax and interstitial disease such as lung fibrosis, not seen on CXR.

Spiral CT chest investigations can detect pulmonary embolus and dissecting aortic lesions.

Useful in assessment of patients for lung parenchymal resection to predict the effect of resection on overall pulmonary performance (resecting a non-ventilated/perfused lung will reduce shunt and should improve oxygenation).

Early mobilisation reduces the incidence of thromboembolic disease.

Chart respiratory rate and S_pO₂.

Seek assessment and advice of intensive care/outreach team early if patient does not respond to initial treatment.

Depression of respiratory function can occur for up to 72hr postoperatively and is most common at night. Supplemental oxygen should be delivered for at least this period of time particularly if receiving opioids.

Preoperative measurement of PaO₂/SaO₂ and PaCO₂ is essential to establish a realistic target for each patient.

Patients who chronically retain CO₂ (advanced COPD) may be dependent on hypoxaemia as their main ventilatory drive due to down-regulation of central chemoreceptors. The concentration of delivered oxygen should be controlled (e.g. by Venturi mask) and titrated, in order to optimise oxygenation and prevent hypoventilation. Adequate monitoring should be available, ideally using serial ABG measurement (pulse oximetry shows only S_pO₂).

Humidification of oxygen aids physiotherapy and sputum clearance.

However, patients with lung disease are at increased risk of pulmonary oedema (a dilated right ventricle may mechanically compromise the function of the left ventricle). Fluid overload is poorly tolerated in these patients and a high index of suspicion should be maintained.

Readings from central venous catheters may be misleading in the presence of pulmonary hypertension or right ventricular failure (cor pulmonale).

Regular oral or IV paracetamol and, where not contraindicated, NSAIDs should be prescribed. NSAIDs should be used with caution in the elderly as renal function may be compromised and they may induce fluid retention.

Patients with lung dysfunction may benefit from local or regional anaesthesia. The sedative effects of systemic opioids can be avoided. The surgeon may be able to place a catheter for regional anaesthesia at the time of operation (e.g. paravertebral catheter for thoracotomy).

The benefits of opioid-based analgesia (patient control, mobility, and avoidance of catheterisation) should be weighed against the benefits of regional analgesia (avoidance of high-dose systemic opioids, preservation of respiratory function) and discussed with the patient preoperatively.

Involve the pain management team early in the postoperative period, requesting at least daily reviews.

Patients may require admission for ventilatory support (CPAP, BIPAP, invasive ventilation) or increased levels of monitoring and nursing care that are not available on the surgical ward.

Adult patients with simple coryza are not at significantly increased risk of developing postoperative pulmonary problems, unless they have pre-existing respiratory disease or are having major abdominal or thoracic surgery.

Laryngospasm may be more likely in patients with a recent history of upper respiratory tract symptoms who are asymptomatic at the time of surgery.

Compared with asymptomatic children, children with symptoms of acute or recent upper respiratory tract infection are more likely to suffer transient postoperative hypoxaemia (S_pO₂ <93%). This is most marked when intubation is necessary.

Respiratory tract mucus is produced in greater quantities, but mucociliary clearance is less efficient. Smokers are more susceptible to respiratory events during anaesthesia and to postoperative atelectasis/ pneumonia. Abdominal or thoracic surgery and obesity increase these risks.

Carboxyhaemoglobin (COHb) levels may reach 5–15% in heavy smokers, causing reduced oxygen carriage by the blood. COHb has a similar absorption spectrum to oxyhaemoglobin and will cause falsely high oxygen saturation readings.

Increased airway irritability increases coughing, laryngospasm, and desaturation during induction and airway manipulation (e.g. laryngeal mask insertion). Avoid by using a less irritant volatile (e.g. sevoflurane) and deepening anaesthesia slowly.

Maintaining spontaneous breathing via an ETT or LMA may be awkward due to airway irritation—consider local anaesthesia to the vocal cords, opioids, relaxants, and IPPV.

Smokers unwilling to stop preoperatively will still benefit by refraining from smoking for 12hr before surgery. During this time the effects of nicotine (activation of the sympathoadrenergic system with raised coronary vascular resistance) and COHb will decrease.

The incidence of perioperative bronchospasm and laryngospasm in asthmatic patients undergoing routine surgery is <2%, especially if routine medication is continued.

The frequency of complications is increased in patients >50yr and in those with active disease.

Poorly controlled asthmatics are at risk of perioperative problems (bronchospasm, sputum retention, atelectasis, infection, respiratory failure).

Do not anaesthetise a patient for elective surgery whose asthma is not optimally controlled.

Assess exercise tolerance (e.g. breathlessness when climbing stairs, walking on level ground, or undressing) and general activity levels.

Document any allergies/drug sensitivities, especially the effect of aspirin/NSAIDs. The prevalence of aspirin-induced asthma (measured by oral provocation) is 21% in adult asthmatics and 5% in paediatric asthmatics. Much lower rates are quoted if verbal history is used to assess prevalence (3% and 2%, respectively).

Examination is often unremarkable but may reveal chest hyperinflation, prolonged expiratory phase, and wheeze. The presence or absence of wheeze does not correlate with severity of underlying asthma.

For patients with severe asthma, consider additional medication or treatment with systemic steroids.

Patients with mild asthma (peak flow >80% predicted and minimal symptoms) rarely require extra treatment prior to surgery.

Emphasise benefits of good compliance with treatment prior to surgery. Consider doubling dose of inhaled steroids 1wk prior to surgery if there is evidence of poor control (>20% variability in PEFR). If control is very poor, consider review by chest physician and a 1wk course of oral prednisolone (20–40mg daily).

Viral infections are potent triggers of asthma, so postpone elective surgery if symptoms suggest URTI.

There is an association with nasal polyps in atopic patients.

Spirometry gives a more accurate assessment. Results of peak flow and spirometry are compared with predicted values based on age, sex, and height (see p. 1264).

Blood gases are only necessary in assessing patients with severe asthma (poorly controlled, frequent hospital admissions, previous ICU admission), particularly prior to major surgery.

Add nebulised salbutamol 2.5mg to premedication.

Avoid histamine-releasing drugs or use with care (morphine, d-tubocurarine, atracurium, mivacurium).

Intubation may provoke bronchospasm—consider potent opioid cover (alfentanil). LA to the cords may help.

When asthma is poorly controlled, regional techniques are ideal for peripheral surgery. Spinal anaesthesia or plexus/nerve blocks are generally safe, provided the patient is able to lie flat comfortably.

Where general anaesthesia is necessary, use short-acting anaesthetic agents. Short-acting opioid analgesics (e.g. alfentanil, remifentanil) are appropriate for procedures with minimal postoperative pain or when a reliable regional block is present.

Patients with severe asthma (previous ICU admissions, brittle disease) undergoing major abdominal or thoracic surgery should be admitted to HDU/ICU for postoperative observation.

Extubate and recover in sitting position.

Following major abdominal or thoracic surgery, good pain control is important and epidural analgesia is frequently the best choice, provided widespread intercostal blockade is avoided.

For patient-controlled analgesia (PCA), consider fentanyl if morphine has previously exacerbated bronchospasm.

Prescribe oxygen for the duration of epidural or PCA.

Prescribe regular nebuliser therapy with additional nebulised bronchodilators as needed.

Review dose and route of administration of steroid daily.

Regular NSAIDs can be used if tolerated in the past. Avoid in brittle and poorly controlled asthmatics.

If there is increasing dyspnoea and wheeze following surgery, consider other possible contributing factors (left ventricular failure and pulmonary emboli are potent triggers of bronchospasm). Also consider fluid overload and pneumothorax (check for recent central line).

The majority of patients with COPD have been tobacco smokers for a significant period of their lives. Other factors associated with COPD include occupational exposure to dusts and atmospheric pollution, poor socio-economic status, repeated viral infections, A1-antitrypsin deficiency, and regional variation.

Patients with predominantly emphysema may be thin, tachypnoeic, breathless at rest, and, although hypoxic, develop CO₂ retention only as a late or terminal event. Patients with predominantly chronic bronchitis are frequently overweight with marked peripheral oedema, poor respiratory effort, and CO₂ retention. These classical stereotyped pictures of ‘pink puffer’ or ‘blue bloater’ are infrequently seen compared with the majority of patients, who have a combination of features.

Non-invasive ventilation via a full face or nasal mask (BiPAP) is increasingly used to treat acute severe exacerbations of COPD. This technique may be used to assist severely affected patients through the postoperative phase of major surgery. Preoperative training is essential in conjunction with a respiratory unit or HDU.

Establish exercise tolerance—ask specifically about hills and stairs. A formal assessment of exercise tolerance such as stair climbing correlates well with pulmonary function tests.

Ensure any element of reversible airflow obstruction (asthma) is optimally treated. Consider a trial of oral prednisolone, combined with review by a respiratory physician.

Pulmonary hypertension and right ventricular failure may follow severe or chronic pulmonary disease—optimise treatment of heart failure if present.

Change to nebulised bronchodilators prior to surgery and continue for 24–48hr afterwards.

Check ABGs if the patient has difficulty climbing one flight of stairs, is cyanotic, has S_pO₂ <95% on air, or has peripheral oedema.

ECG may reveal right heart disease (right ventricular hypertrophy or strain). Consider echocardiography.

CXR is useful to exclude active infection and other pathology (e.g. bronchial carcinoma).

If patients have severe COPD (exercise tolerance less than one flight of stairs or CO₂ retention), postoperative respiratory failure is likely after abdominal or thoracic surgery. Plan for elective HDU/ICU admission.

Avoid intubation where possible—however, some patients (particularly those who are obese, breathless, and require long operations) are unsuitable for a spontaneously breathing technique. Patients with heavy sputum production may benefit from endotracheal toilet.

Be vigilant for pneumothorax.

Mobilise as early as possible.

Regular physiotherapy to prevent atelectasis and encourage sputum clearance.

Give oxygen as appropriate.

If the patient becomes pyrexial with more copious or purulent sputum send a sample for culture and start antibiotics. Oral amoxycillin or clarithromycin are usually sufficient for mild exacerbations. If the patient becomes systemically unwell treat as pneumonia.

Continue with nebulised salbutamol (2.5mg qds) and ipratropium (500µg qds) until fully mobile. Change back to inhalers at least 24hr before discharge.

If the patient is slow to mobilise consider referral to a pulmonary rehabilitation programme.¹

Once established, bacterial infections can be difficult or impossible to eradicate. Pseudomonas aeruginosa is a common pathogen that may be present for many years and be associated with intermittent exacerbations of respiratory symptoms.

The mainstay of treatment for bronchiectasis is regular physiotherapy, frequent courses of appropriate antibiotics, and treatment of any asthmatic symptoms.

Consultation with the patient's chest physician is essential.

Send sputum sample for culture before surgery. A course of IV antibiotics and physiotherapy for 3–10d immediately prior to surgery may be necessary. Prior to major surgery, consider starting IV antibiotics on admission. Use current or most recent sputum culture to guide appropriate prescribing. If in doubt assume that the patient has Pseudomonas aeruginosa and use a combination such as ceftazidime and gentamicin, or imipenem and gentamicin.

Maximise bronchodilation by converting to nebulised bronchodilators.

Increase dose of prednisolone by 5–10mg/d if on long-term oral steroids.

Postpone elective surgery if the patient has more respiratory symptoms than usual.

Send sputum sample for culture.

Although it is desirable to avoid intubation, this will be necessary for all but the shortest operations to facilitate intra-operative removal of secretions.

Use short-acting anaesthetic and analgesic agents where postoperative pain is minimal or regional analgesia can be used.

Extubate and recover in sitting position.

Ensure that the patient will receive physiotherapy immediately postoperatively. Contact on-call physiotherapist if necessary.

Monitor S_pO₂, giving supplemental oxygen to achieve adequate oxygenation (guided by preoperative value).

Continue appropriate IV antibiotics for at least 3d postoperatively or until discharged.

Maintain adequate nutrition, especially if any malabsorption.

Refer to respiratory physician early if there is any deterioration in respiratory symptoms.

In the lung, viscid mucus causes plugging, atelectasis, and frequent chest infection (particularly Pseudomonas). Treatment is primarily clearance of secretions by postural drainage and antibiotic treatment of infections.

The perioperative complication rate in cystic fibrosis is ∼10% (mostly pulmonary), but half of this is for minor ENT procedures.

Lung transplantation has an 82% 1yr survival.

Clinical signs can be misleading.

Spirometry: FEV₁ may be prognostic.

Always inform the patient's physician of an admission to a surgical ward.

Intubation allows bronchial toilet. Monitor for pneumothorax.

80% of cystic fibrosis patients have pancreatic malabsorption. Maintaining adequate nutrition after surgery is essential as is the advice of an experienced dietician.

An initial inflammatory reaction centred on the alveoli impairs gas exchange. This is followed by collagen deposition and fibrosis, resulting in lungs that are smaller in volume and less compliant to inflation.

Causes of pulmonary fibrosis include autoimmune disorders (e.g. rheumatoid arthritis, scleroderma), exposure to inhaled dusts (e.g. asbestos), allergenic substances (bird fancier's and farmer's lung), ingested substances (especially drugs such as amiodarone, chemotherapy agents, paraquat poisoning), and fibrosis after acute respiratory distress syndrome.

Pulmonary infections rarely trigger a fibrotic response.

Treatment is usually with oral steroids, but other immunosuppressive therapy may be used and young patients may be considered for lung transplantation if severely affected.

Many patients are stable and only slowly deteriorate over some years. These patients may tolerate surgery relatively well.

Obtain lung function tests including spirometry, lung volumes (all are reduced), and gas transfer if these have not been done within previous 6–8wk.

CXR changes will be according to the underlying condition.

Where IPPV is necessary, minimise peak airway pressure using pressure-controlled ventilation, with high rate and low tidal volume.

For those on steroids, increase dose on day of surgery and continue an extra 5–10mg of prednisolone per day until the patient goes home.

Maintain a high index of suspicion for pneumothorax.

Extubate in a sitting position.

Give supplemental oxygen and maintain S_pO₂ >92%.

Good physiotherapy and analgesia are vital to achieve sputum clearance. With severe disease, minor respiratory complications may precipitate respiratory failure.

Mobilise early.

Treat respiratory infection vigorously.

Ensure steroid cover continues in appropriate formulation.

Central apnoea (10%) is due to intermittent loss of respiratory drive.

Most patients are treated with CPAP applied overnight by a nasal mask.

In children, obstructive sleep apnoea is most commonly associated with adenotonsillar hypertrophy, but the severity of obstructive sleep apnoea is not always proportional to the size of the tonsils and adenoids.

Patients with sleep apnoea syndrome are at risk of perioperative airway obstruction and respiratory failure while under the effects of sedative drugs.

Ask about daytime hypersomnolence (falling asleep during daily activities, e.g. reading or driving).

Ask partner about snoring and whether apnoeic spells have been noted at night (patient usually unaware).

Obesity and a collar size of >17 inches (43cm) are risk factors for obstructive sleep apnoea—weight reduction is beneficial.

Obstructive sleep apnoea should be considered in all children presenting for adenotonsillectomy.

Ensure that management of associated conditions such as obstructive airway disease, hypertension, and cardiac failure is optimal.

Consider a respiratory opinion in patients with peripheral oedema and oxygen saturation <92%.

Ask patients to bring their own CPAP machine and mask for postoperative use. Ensure that ward staff are familiar with set-up and running of equipment.

If ECG shows right ventricular strain (3% of children presenting for adenotonsillectomy) echocardiography is indicated to exclude right ventricular hypertrophy.

Obtain baseline ABGs.

Avoid night sedation or sedative premedication.

Anticipate that mask ventilation and intubation may be difficult and prepare for this.

Regional anaesthesia/analgesia and postoperative analgesia will avoid or minimise use of general anaesthetic agents and sedative opioid analgesics. Reduce doses of all sedative/anaesthesia drugs—patients are very sensitive. Use short-acting anaesthetic/analgesic agents where postoperative pain is minimal.

Give NSAIDs and paracetamol.

Patients are best managed in the HDU or ICU.

A few hours of postoperative ventilation may be required after major surgery.

Continuous pulse oximetry should be used on the ward.

Aim to maintain the oxygen saturation that the patient had preoperatively, titrating oxygen to the minimum required. A few patients may develop CO₂ retention with oxygen therapy. Serial blood gas analysis may be necessary in drowsy patients at risk of CO₂ retention.

Cardiac effects (in 20%). Right ventricular failure secondary to lung disease. Myocardial and valvular granulomata are rare. Conduction abnormalities, VT, and sudden death have been reported.

Other effects include skin involvement, uveitis/iritis, and hypercalcaemia.

May have extensive pathology but only minor symptoms.

Note steroid treatment or other immunosuppressive drugs.

ECG may show right ventricular hypertrophy or arrhythmias.

Check serum Ca²⁺ for hypercalcaemia (treat with systemic steroids).

Consider regional analgesia for abdominal surgery if significant respiratory disease.

Give appropriate steroid cover if needed.

Good postoperative analgesia.

Chest physiotherapy/breathing exercises.

Complications of immunosuppressive treatment

The underlying condition (emphysema, A1-antitrypsin deficiency, pulmonary fibrosis, primary pulmonary hypertension, cystic fibrosis)

Unrelated reasons

Hypoxic vasoconstriction is unimpaired.

Lymphatic drainage is severed but then re-established 2–4wk post transplantation. Transplanted lungs are at particular risk of pulmonary oedema, especially in the early postoperative period.

In double lung transplant, the heart may be denervated and has a higher resting heart rate (90–100bpm). It may be more susceptible to arrhythmias.

Monitor neuromuscular function and avoid high doses of opioid in order to achieve early extubation.

Intubation should be performed to leave the tube just through the cords and the cuff carefully inflated and checked intra-operatively to minimise the risk of damage to the tracheal/bronchial anastomosis. If a double lumen tube is required it should be placed under direct vision using a fibrescope.

Strict attention to fluid balance is required.

Aim for early return of pulmonary function and extubation.