PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

Perioperative management ofthe patient with respiratorydiseaseJanis Shaw

Analysis of co-existing medical problems in one sampleof 1911 patients who died within 3 days followingemergency surgery

Co-existing medical problems at the time

of final operation (answers may be multiple)

Frequency (%)

None/question not answered 4

Cardiovascular 76

Respiratory 56

Neurological 37

Alimentary 25

Renal 21

Sepsis 20

Endocrine 17

Musculoskeletal 13

AbstractCardiorespiratory disease is the commonest cause of perioperative

morbidity and mortality in the western world. Each year in the UK, around

25,000 to 30,000 patients die within 30 days of surgery. The most impor-

tant pulmonary complications are exacerbation of existing respiratory

disease, pneumonia and respiratory failure. The key to reducing problems

in this group of patients is identification of those individuals most at risk

and optimization of medical management. A perioperative care plan can

then be instituted for each individual patient in order to gain maximum

benefit from available therapeutic interventions. While complications can

never be totally prevented, a worsening of vital signs generally precedes

impending critical illness. Prompt recognition of any physiological deteri-

oration and early intervention are the key to avoiding a poor outcome in

such circumstances. Early warning scoring (EWS) systems have been

implemented in many postoperative care areas to draw attention to any

deterioration in vital signs at an early stage. This article focuses on the

perioperative management of patients with respiratory disease.

Keywords Cardiopulmonary exercise test; early warning score; peri-

operative risk; postoperative lung function; postoperative respiratory

failure; pulmonary function tests

Overall strategy and general assessment

Of the 25,000 to 30,000 patients who die within 30 days of

surgery in the UK per annum, the majority are >65 years old and

are suffering from one or more co-existing medical disorders at

the time of operation. Data from the National Confidential

Enquiry into Perioperative Deaths (NCEPOD)1 shown in Table 1

give a detailed analysis according to the prevalence of co-existing

medical problems of one sample of 1911 patients who died

within 3 days of surgery. Respiratory disease ranks only second

to cardiovascular disease as a contributory comorbidity.

A detailed history and physical examination, together with the

sensible application of preoperative screening tests should

identify those patients who fall into a higher risk category. The

surgical team should aim to:

� make an initial assessment of the severity of the respiratory

disease process

� assess the patient’s functional capacity

� ensure optimal medical management of the underlying

disease and treat any current chest infection

Janis Shaw FRCA is a Consultant Cardiothoracic Anaesthetist at

Manchester Royal Infirmary, Manchester, UK and Honorary Lecturer at

the University of Manchester. Conflicts of interest: none declared.

SURGERY 28:9 427

Any patient deemed to fall into a higher than normal risk cate-

gory should be referred, either directly for an anaesthetic

opinion, or via a respiratory physician if it appears that the

patient’s respiratory status could be improved. This strategy

should avoid the ‘last-minute’ cancellation of an elective proce-

dure. In an emergency situation, options for improving patient

status are limited but a rapid referral for an emergency consul-

tation and effective multidisciplinary team working can often

improve outcomes.

Risk factors associated with postoperative pulmonary

complications

A recent systematic literature review2 identified a number of

factors associated with increase likelihood of postoperative

pulmonary complications and these are dependent on:

� patient-related risk factors

� procedure-related risk factors

Patient-related risk factors

Age: unadjusted risk attributable to increasing age was previ-

ously believed to be due to the accumulation of comorbid

conditions, but evidence now shows that advancing age is an

important independent predictor of postoperative pulmonary

complications. NCEPOD data shows that the risk rises sharply

over the age of 65. Patients aged 70 or over have an approxi-

mately four times greater risk of developing postoperative

pulmonary complications.

Respiratory disease status: patients with respiratory disease

frequently develop pulmonary complications following surgery.

A functional classification of some of the problems associated

with chronic pulmonary disease is shown in Table 2. Meta-

analysis has shown that chronic obstructive pulmonary disease

(COPD) is the most frequently identified risk factor and is more

likely to be associated with postoperative respiratory failure than

either chronic restrictive pulmonary disease or other restrictive

pathologies.

Haematological 11

Hepatic 6

Other 11

Table 1

� 2010 Elsevier Ltd. All rights reserved.

Functional classification of respiratory disorders

Functional change Disease process

Air trapping and

bronchospasm

C Asthma

C Emphysema

Excessive pulmonary

secretions

C Chronic bronchitis

C Intercurrent chest infection

C Bronchiectasis

C Pulmonary oedema

Parenchymal lung disease

Showing a

restrictive pattern

C Idiopathic fibrotic disease

C Connective tissue disorders

C Sarcoidosis and primary lung disease

C Drug-induced lung disease

Extraparenchymal disease

Showing a

restrictive pattern

C Chest wall abnormalities

C Pleural disease

C Neuromuscular disorders

Reduced ventilatory

capacity

C Central nervous system depression

C Diaphragmatic paralysis

C Obstructive sleep apnoea

Table 2

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

Other comorbidities: The American Society of Anesthesiologists’

(ASA) Classification, which predicts perioperative mortality, has

been shown to predict both pulmonary and cardiac postoperative

complications. Patients in ASA classes IIeV have a fourfold

greater risk of developing postoperative pulmonary complica-

tions. There is particularly good evidence to support identifica-

tion and treatment of any element of congestive cardiac failure as

this is independently associated with an increased risk of

pulmonary complications.

Smoking history: there is a modest increase in the risk of

postoperative pulmonary complications in ex-smokers, whereas

current smokers have an approximately fivefold greater risk. In

order to reduce this risk, patients need to stop smoking 8 weeks

prior to surgery. Curiously, patients who stop smoking less than

8 weeks before surgery may have a slightly increased risk. There

may be some benefit in abstaining from smoking for 12 hours

prior to surgery as this will reduce the level of carbox-

yhaemoglobin and improve oxygen-carrying capacity.

Functional dependence: functional dependence has been

shown to be a risk factor for postoperative pulmonary compli-

cations. Total functional dependence is the inability to perform

any activities of daily living and carries a threefold increase in

risk. Partial dependence is the need for equipment or devices

and assistance from another person for some activities of daily

living and carries a 1.5 times increase in risk.

Procedure-related risk factors

These include surgical factors such as the site of the surgery, the

duration of surgery, anaesthetic technique and emergency

surgery. The major procedure-related risk factors have been

shown to confer a higher risk for pulmonary complications than

the patient-related risk factors.

SURGERY 28:9 428

Surgical site: patients undergoing open aortic surgery are at the

greatest risk for postoperative pulmonary complications e

a sevenfold increase in incidence. Other high-risk surgeries

include thoracic and upper abdominal procedures, which carry

a three- to fourfold increase in risk, respectively.

Duration of surgery: prolonged surgery approximately doubles

the risk of developing postoperative pulmonary complications.

The definition of prolonged surgery varied between 2.5 and

4 hours in published studies.

Anaesthetic technique: the administration of general anaes-

thesia doubles the risk of developing postoperative pulmonary

complications compared with the use of regional or local

anaesthetic techniques.

Emergency surgery: again the risk of postoperative pulmonary

complications is doubled when the surgery needs to be per-

formed as an emergency rather than as an elective procedure.

Preoperative assessment and risk stratification

A detailed history and examination should be performed to

identify all known potential risk factors and to evaluate the

patient’s pre-existing pulmonary status.

Respiratory disease status

Any element of airway obstruction should be well controlled prior

to elective surgery. Detailed recommendations for the manage-

ment of asthmatic patients have recently been published jointly by

the British Thoracic Society and the Scottish Intercollegiate

Guidelines Network (SIGN).3 Inhaled b2 agonists (e.g. salbuta-

mol), inhaled steroids (e.g. beclomethasone) and antimuscarinic

drugs (e.g. ipratropium) are themainstays of treatment and should

always be continued perioperatively. Current or recent treatment

with systemic steroids invariably indicates greater severity of

disease or a recent exacerbation. Any patient taking 10mg ormore

of prednisolone daily will require perioperative hydrocortisone

supplementation. If active pulmonary infection is suspected the

patient’s sputum should be obtained for laboratory culture and

sensitivity and a course of appropriate antibiotics should be

prescribed once sensitivities are known. Referral to a chest

physician may be indicated if the history suggests that respiratory

status may be improved by further optimization of therapy. Some

patients who have very poor control may benefit from a week’s

course of systemic steroids in the perioperative period.

Further investigations to estimate risk

Routine investigations for patients with respiratory disease

generally include blood tests, chest X-ray and pulmonary func-

tion testing.

Blood tests: full blood count, urea and electrolytes and liver

function tests should be performed as a routine. A small number

of studies have identified raised serum levels of urea and

creatinine as independent risk factors. Hypoalbuminaemia (<36

g/litre) has been shown to be a very important predictor of

30-day perioperative morbidity and mortality.

Chest X-ray: most studies of the value of preoperative chest

X-rays have evaluated the impact of abnormal findings on

� 2010 Elsevier Ltd. All rights reserved.

A comparison of pulmonary function test results inrestrictive and obstructive disease (FVC, forced vitalcapacity; FEV1, forced expiratory volume in 1 s)

Measurement Restrictive disease Obstructive disease

FVC Decreased Normal or decreased

FEV1 Decreased Normal or decreased

FVC/FEV1 Normal Decreased

Table 3

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

perioperative management rather than postoperative pulmonary

complications. In a series of eight studies, 23.1% of preoperative

chest radiographs showed an abnormality but only 3% influ-

enced management.

Pulmonary function tests: an understanding of the normal

physiological lung volumes, shown in Figure 1, is essential when

interpreting many of the routinely performed preoperative

pulmonary function tests.

Spirometry: forced vital capacity (FVC) and forced expiratory

volume in 1 second (FEV1) are the most common pulmonary

function tests performed as part of routine preoperative assess-

ment. The patient performs a maximum inspiration to total lung

capacity and then breathes out as quickly as possible to maximum

expiration. The FVC and FEV1,which are typicallymeasured using

a Vitalograph or a mobile device, may be used to assess the nature

and severity of respiratory disease (see Table 3). The FEV1/FVC

ratio is normal (over 70%) in restrictive lung disease but reduced

in obstructive lung disease. If the patient has an obstructive

pattern, measurements should be repeated 5e10 minutes after

administration of an inhaled bronchodilator to assess acute

reversibility. The tests are very dependent on patient effort and can

be unreliable. In terms of risk stratification, it has been shown that

most patients identified as high risk by spirometry canbe identified

equally well by clinical evaluation. The FEV1 has been validated as

the most useful single measure for predicting poor outcome. An

FEV1< 0.8 l and an FVC< 1 l indicate that the patient’s cough will

be poor and respiratory support is likely to be required following

major surgery.

Peak expiratory flow rate: measurement of peak expiratory

flow rate (PEFR) can be performed at the bedside with a peak

flow meter. PEFR falls during obstructive episodes and is useful

for monitoring the response to bronchodilator therapy. Coughing

is ineffective when PEFR < 200 litres/minute.

Physiological lung volumes (litres). Normal tidalventilation and one large vital capacity breathare shown

Ph

ysio

log

ica

l lu

ng

vo

lum

es

(lit

res)

5.0

3.0

2.5

1.25

0

Residual volume

Total

lung

capacity

Vital

capacity

Inspiratory

capacity

Expiratory

reserve

volume

Tidal

volume

Functional

residual

capacity

Inspiratory

reserve

volume

Figure 1

SURGERY 28:9 429

Diffusing capacity for carbon monoxide: parenchymal

(alveolar-capillary membrane) lung function is typically assessed

by measuring the diffusing capacity for carbon monoxide

(DLCO). Patients requiring more than simple spirometry (i.e.

DLCO, arterial blood gas analysis) should be assessed using

a multidisciplinary approach.

Assessment of functional capacity

Cardiorespiratory reserve should be expressed in Metabolic

Equivalents of Task (MET). Patients should be able to perform

four METs (equivalent to climbing a flight of stairs) of physical

activity or more if they are to be considered for major surgery.

Patients’ estimations of their exercise capability are very

subjective and may frequently be overestimated.

Cardiopulmonary exercise testing (CPET) is regarded as

a very reliable, objective test of functional capacity.4 It has now

been recognized as an acceptable method of quantifying

a patient’s ability to respond to the increased metabolic demands

of major surgery.5 CPET is currently available in more that 30

centres across the UK and provides a safe, non-invasive,

repeatable, individual assessment of combined pulmonary,

cardiac and circulatory function. If CPET is not available, simple

walk tests such as the 6-minute walk test (6MWT) provide an

acceptable alternative measure of global cardiorespiratory func-

tion. The 6MWT measures how far a patient can walk along a flat

corridor turning around cones at each end. A median distance

attained is around 500e600 m in healthy subjects.

Perioperative care

A perioperative care plan should be produced for each patient.

All patients having major surgery and identified as falling into

a high-risk category for postoperative pulmonary complications

should be cared for in an appropriately staffed high-dependency

(level 2) or intensive therapy unit (level 3) facility. In ideal

circumstances, all patients suffering from significant respiratory

problems would go to a high-care area following surgery.

Unfortunately, the lack of resources often dictates that patients

may need to return to a ward environment. The difficult decision

of where to send the patient in the immediate postoperative

period should be undertaken by the multidisciplinary team.

Factors affecting complication rates

There are many reasons why patients with pre-existing pulmo-

nary disease develop complications. The most important respi-

ratory problems in this group of patients are exacerbation of

existing respiratory disease, pneumonia and respiratory failure.

There is a complex relationship between all the factors involved

in the development of postoperative respiratory failure

� 2010 Elsevier Ltd. All rights reserved.

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

(Figure 2). This section identifies the risk factors which have not

yet been considered and discusses some of the pathophysiology

involved in the development of postoperative respiratory failure.

Metabolic response to surgery: the inflammatory response

provoked by major surgery increases the body’s oxygen

consumption by up to 40% or more. This state of increased

oxygen demand, which persists for several days is largely met by

an increase in cardiac output. Any disease which affects the

function of the cardiac or respiratory systems may mean the

patient is unable to increase oxygen delivery to meet these

increased metabolic demands.

Effects of anaesthesia: significant atelectasis occurs within

minutes of the induction of general anaesthesia. General anaes-

thesia reduces functional residual capacity (FRC) of the lungs by

as much as 20%. Collapse of the airspaces occurs as the FRC falls

below the lung’s closing capacity (CC). The CC is the lung

volume at which the small dependent airways collapse causing

basal (dependent) alveolar atelectasis and ventilation/perfusion

mismatch leading to hypoxaemia. Decreased FRC is associated

with increasing age, obesity and the supine position. If possible,

general anaesthesia should be avoided in patients with severe

respiratory disease. Local or regional anaesthetic techniques are

preferable. For peripheral operations, spontaneously breathing

techniques may lead to less postoperative morbidity and are

Factors which affect the development of postoperative respir

Atelecta↓ Ventilation

and impaired cough

Oxygen thand hype

Effects of chroniclung disease

Effect of postoperativeopioids

↑ Mucus seChest wall & respiratory

muscle functionNeurological

Effects of anaand surg

Figure 2

SURGERY 28:9 430

often well tolerated. If surgery cannot be undertaken without

muscle relaxation a short-acting neuromuscular blocking drug

should be administered as part of the anaesthetic technique.

Some anaesthetists use a combined general/epidural anaesthetic

technique for thoracic major abdominal surgery in the hope of

reducing the risk of complications.

Postoperative hypoventilation: anaesthetic drugs may have

residual effects leading to decreased central respiratory drive and

respiratory muscle weakness. The FRC may be further reduced

by incisional pain and diaphragmatic dysfunction, particularly

after upper abdominal and thoracic procedures. Inadequate

analgesia may impair the ability to cough and clear secretions.

Effective postoperative analgesia is essential but a drug-induced

reduction in central respiratory drive is often associated with the

administration of potent opioids. The used of a regional anaes-

thetic technique (i.e. an epidural) is often effective in allowing

deep breathing, coughing and early mobilization.

Other intraoperative factors: administration of crystalloids,

postoperative fluid retention secondary to vasopressin and

aldosterone and hypoproteinaemia may predispose patients with

impaired left ventricular function to pulmonary oedema, which

increases the alveolarearterial oxygen gradient and reduces lung

compliance. Other factors that may increase alveolar-capillary

permeability include:

atory complications and respiratory failure

sis

↓ Gas exchange

erapy roxia

Postoperative respiratory

failure

Alveolar-capillary membrane

function & oedema

Metabolic response to surgery

cretion Airway

esthesia ery

� 2010 Elsevier Ltd. All rights reserved.

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

� sepsis

� shock

� transfusion of blood and blood products

� high volume mechanical ventilation

� aspiration of gastric contents

Many anaesthetic and surgical procedures are associated with an

increased risk of aspiration of gastric contents leading to bron-

chospasm, airway obstruction, pneumonia or acute lung injury.

Selective use of nasogastric tube drainage after abdominal

surgery may help to prevent postoperative respiratory

complications.

Strategies to reduce complications

A recent systematic review of the literature on interventions to

prevent postoperative pulmonary complications6 is summarized

below:

Strategies of proven benefit: good evidence suggests that lung

expansion therapy reduces postoperative pulmonary risk after

abdominal surgery. Examples of lung expansion therapy include:

� incentive spirometry

� deep breathing exercises

� continuous positive airway pressure (CPAP)

All reduce postoperative pulmonary risk after abdominal

surgery.

Strategies of probable benefit: two strategies of probable benefit

are:

� selective use of nasogastric tube decompression following

abdominal surgery

� use of short-acting neuromuscular blocking agents if muscle

relaxation is required

Strategies of possible benefit: possible benefit may be gained

from the use of:

� laparoscopic procedures compared with open abdominal

operations to reduce pain and pulmonary compromise as

measured by spirometry and oxygenation

� regional anaesthetic techniques such as a continuous epidural

for postoperative pain relief

Strategies of unproven benefit: evidence is insufficient to judge

the potential benefit of:

� preoperative smoking cessation

� the use intraoperative epidural anaesthesia

Early warning score sheet

Observations Score

3 2 1 0

Temperature (�C) �35.0 35.1e36.0 36.1e37.9

Systolic blood

pressure (mmHg)

�70 71e80 81e100 101e199

Heart rate �40 41e50 51e100

Respiratory rate �8 9e14

Central nervous system New confusion Alert

Table 4

SURGERY 28:9 431

More good-quality efficacy trials of sufficient size are needed to

accurately examine complication rates.

Strategies of no benefit: no benefit can be demonstrated

from:

� routine parenteral or enteral hyperalimentation, despite the

fact that malnutrition is associated with increased risk for

postoperative pulmonary complications

� routine perioperative monitoring using a pulmonary artery

flotation catheter

Summary of important strategies to reduce pulmonary

complications

Careful preoperative assessment using a multidisciplinary

approach together with early optimization of medical

management is the key to reducing potential problems. Phys-

ical therapies that aim to improve lung expansion and sputum

clearance, combined with early mobilization, seem to be

crucial in avoiding postoperative respiratory failure. All high-

risk patients with respiratory disease presenting for elective

surgery should have a preoperative consultation with a phys-

iotherapist to learn appropriate techniques which will maxi-

mize postoperative care. Effective postoperative analgesia is

essential to deep breathing, coughing and clearance of secre-

tions, and early mobilization. Postoperative oxygen therapy

should be administered for several days until the patient has

recovered from the metabolic demands imposed by major

surgery.

Recognition of postoperative pulmonary complications

Complications can never be entirely prevented. Every year

large numbers of patients suffer unnecessary morbidity and

mortality because the early signs of catastrophic deterioration

were not noticed. In response, most centres have adopted the

use of early warning scoring (EWS) systems. The EWS relies

on observations of the patient’s physiological status that

reflect the clinical evaluation of oxygen delivery and organ

perfusion. This ensures small deviations in vital signs are

noticed rather than waiting for a more obvious change in

a single variable. Table 4 shows a typical modified EWS

record. It must be remembered that the EWS is a tool and is

only as good as the staff using it. Multidisciplinary interven-

tion is required when an abnormal trend has been recognized.

The team need to familiarize themselves, not just with the

1 2 3

38.0e38.9 �39.0

�200

101e110 111e129 �130

15e20 21e29 �30

Responds to verbal commands Responds to pain No response

� 2010 Elsevier Ltd. All rights reserved.

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

local scoring system, but also with local critical care outreach

services which are in place to manage patients who are

deteriorating. A

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581e95.

SURGERY 28:9 432

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� 2010 Elsevier Ltd. All rights reserved.