PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

The perioperativemanagement of patients withmusculoskeletal disease andfor the burns patientPeter Berry

Patricia Richardson

AbstractMusculoskeletal disease may exist as a single or multi-system disorder

and affects patients in all age groups. Pre-anaesthetic assessment should

be focussed on defining the extent of both musculoskeletal disease and

systemic disease, and consideration will need to be given to the manage-

ment of medications in the perioperative period. Limited joint mobility

can hinder dynamic preoperative assessment of cardiorespiratory reserve.

The range of neck movement will influence the choice of anaesthetic tech-

nique and this should be planned well in advance of surgery. The need for

postoperative high dependency or intensive care should be anticipated.

Patients with burns present many potential problems in both the acute

and longer term. Protecting the airway from rapid swelling is an urgent

priority in the acute phase. Large burn injuries cause systemic changes

in fluid balance, temperature control and metabolic rate. Long-term

changes in physiology, pharmacokinetics and mental state need to be

considered when planning perioperative care.

Keywords Anaesthesia; ankylosing spondylitis; burn injury; malignant

hyperpyrexia; muscular dystrophy; musculoskeletal disease; rheumatoid

arthritis

ANAESTHESIA IN PATIENTS WITH MUSCULOSKELETAL DISEASE

Musculoskeletal diseases (MSDs) comprise a wide range of

multi-system disorders that affect all age groups. Whilst some are

very common and others thankfully rare, all are chronic. Patients

affected by these diseases may present either for incidental

surgery or for procedures related to their condition.

Preoperative assessment

The goals of assessment are to assess the likely impact of surgery

and anaesthesia on the patient, and the impact of the patient’s

disease and functional status on the conduct of surgery and

anaesthesia. The elderly, paediatric patients, and patients with

Peter Berry BMed Sci BM BS FRCA is a Fellow in Burns and Plastics

Anaesthesia at St Andrew’s Centre for Plastic Surgery and Burns,

Broomfield Hospital, Essex, UK. Conflicts of interest: none declared.

Patricia Richardson BM MRCP FRCA is a Consultant Anaesthetist at

St Andrew’s Centre for Plastic Surgery and Burns, Broomfield Hospital,

Essex, UK. Conflicts of interest: none declared.

SURGERY 28:9 452

significant comorbidities require additional attention. In many

instances, patients will already have undergone multiple proce-

dures and reviewing the records of previous anaesthetics and

asking directly about problems or preferences will be of benefit.

Poor exercise tolerance is an important predictor of perioper-

ative respiratory and cardiovascular complications. Limited joint

mobility can ‘protect’ patients from symptoms such as angina that

are induced or exacerbated by exercise. Consequently the use of

activity-based cardiorespiratory testing with a treadmill or cycle

ergometer (as in cardiopulmonary exercise, CPEX) will be diffi-

cult. An arm-cycle ergometer, thallium scintigraphy or dobut-

amine stress echocardiography are useful alternatives. Circulating

levels of B natriuretic peptide (BNP)may also be used to assess the

risk of perioperative cardiac events; >300 pg/ml signifies a high

risk whilst <100 pg/ml signifies a low risk.

Assessment of the upper airway is essential when planning

perioperative airway control (see below). Direct laryngoscopy

requires goodmouth opening and the ability to flex the neck while

extending the atlanto-occipital joint. Rheumatoid arthritis may

cause atlanto-axial subluxation, and temporo-mandibular joint

involvement may limit mouth opening. As only 25% of patients

with cervical spine instability have neurological symptoms it is

prudent to assess neck mobility and associated symptoms in the

patient awake, and determine the degree of mechanical instability

with cervical spine radiographs taken in flexion and extension.

Ankylosing spondylosis fuses the spine, reducing neck movement

and rendering tracheal intubation under direct vision extremely

difficult. Congenital (achondroplasia) or acquired (acromegaly,

facial trauma) deformities of the facial bones can also lead to

difficulty with mask ventilation and intubation.

Therapy with disease-modifying drugs will require special

consideration in the perioperative period. Anti-rheumatic drugs such

as gold, penicillamine and corticosteroids can be toxic to the kidneys,

bonemarrowor immunesystem.The risksof reducedwoundhealing

and infection need to be balanced against the risks of stopping

therapy. Corticosteroids must not be stopped abruptly and in those

patientswhohave taken>10mg/dayprednisolone (or equivalent) in

the preceding 3 months, intravenous supplementation will be

required for up to 72 hours because of adrenal suppression. Further

guidance can be found in the British National Formulary.

Many MSDs have a multi-system component and preoperative

assessment should involve questioning to determine the extent of

disease. Boxes 1e3 summarize clinical characteristics of some of

the most frequently encountered diseases and malignant hyper-

pyrexia. This latter, inherited disorder is rare, but patients may

show a fatal response to anaesthetic agents.

Intraoperative management

Airway control

The most appropriate method of achieving safe airway control is

usually dictated by the surgical procedure proposed, patient

positioning and individual patient risk factors. The laryngeal

mask airway (LMA) can usually be inserted with less mouth

opening and neck movement than is required for tracheal intu-

bation, but does not fully protect the airway from aspiration or

allow ventilation with high airway pressures.

Nasal or oral fibreoptic tracheal intubation is considered the

safest means by which to secure the airway when direct

� 2010 Elsevier Ltd. All rights reserved.

Anaesthetic implications of musculoskeletal diseases

Rheumatoid arthritis

C Multi-system disease affecting up to 3% of females and 1% of

males associated with

Temporomandibular joint disease reducing mouth opening.

Atlanto-axial subluxation which may be asymptomatic.

Excessive neck movement which risks cervical cord

compression.

Pulmonary fibrosis causing restrictive changes.

Pleural effusion and pulmonary nodules.

Pericardial effusion (usually asymptomatic), rarely

pericarditis, myocarditis and conduction defects.

Vasculitis effective vessels of any size.

Anaemia, usually normochromic anaemia of chronic

disease.

Secondary anaemia from drug-induced myelosuppression

or occult bleeding with non-steroidal anti-inflammatory

drug (NSAID) use.

Renal impairment; interstitial nephritis, amyloid or drug-

induced.

Peripheral neuropathy due to entrapment (cervical nerves,

ulna nerve at the elbow, etc.) or vasculitis.

C Full blood count, creatinine and electrolytes, electrocardio-

graphy (ECG), chest radiograph necessary for every case.

C Consider cervical spine radiographs, pulmonary function tests

and echocardiography depending on signs and symptoms.

Ankylosing spondylitis

C Kyphosis and fusion of the spine can make intubation difficult

or impossible without fibreoptic techniques.

C Difficult patient positioning and access for central neuraxial

block.

C Pulmonary fibrosis and limited chest expansion can compro-

mise gas exchange.

C Cardiomegaly, aortic regurgitation may be present, rarely

conduction defects.

C Renal impairment, may be due to amyloid.

ScoliosisC Chest deformity causes limited expansion and restrictive defect.

C Plan for postoperative ventilation if vital capacity <50%

predicted.

C Chronichypoxia causespulmonaryhypertension, right ventricular

hypertrophy and consequent failure (cor pulmonale).

C Assess with ECG, echocardiography and pulmonary function

tests.

Box 1

Anaesthetic implications of specific diseases

Myaesthenia gravis

C Autoimmunediseaseof the postsynaptic acetylcholine receptor.

C Muscle weakness causes reduced respiratory reserve, aspira-

tion risk and sensitivity to neuromuscular blocking (NMB)drugs.

C Preoperatively, optimize medical treatment and ask about the

effects of a missed dose.

C Maintain normal anticholinesterase treatment up to time of

induction and restart as soon as possible postoperatively.

C Pulmonary function tests help predict the need for post

operative ventilation.

Dystrophia myotonica

C A group of hereditary degenerative diseases causing persis-

tent contraction of skeletal muscle following stimulation,

progressing to muscle atrophy.

C Muscle contraction is unaffected by regional anaesthesia and

most NMB drugs, but suxamethonium should be avoided.

C Bulbar palsy and reduced gastric emptying cause an aspiration

risk.

C Deterioration of skeletal, cardiac and smooth muscle causes

deterioration in cardiorespiratory function and cardiomyopathy.

C Endocrine dysfunction, central respiratory depression, mental

deterioration, cardiac dysrhythmias and mitral valve prolapse

may occur.

C Postoperatively avoid or minimize opiates. High-dependency

care is essential.

Muscular dystrophy

C A group of hereditary diseases causing atrophy in affected

muscle groups.

C Risk of aspiration due to reduced gut motility and weak

laryngeal reflexes.

C Respiratory muscle weakness causing restrictive defect and

poor cough.

C Heart failure due to myocardial degeneration e avoid cardiac

depressing drugs.

C Kyphoscoliosis due to muscle weakness.

C Avoid suxamethonium and reduce dose of other NMB drugs.

C Postoperatively avoid or minimize opiates. High-dependency

care is essential.

Box 2

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

laryngoscopy and tracheal intubation are expected to be very

difficult. This can be done ‘awake’ using topical local anaes-

thesia, before the induction of general anaesthesia.

Ventilation

Some MSDs are associated with respiratory complications that

must be considered when deciding upon an anaesthetic tech-

nique. Restrictive pulmonary disease may be the result of lung

SURGERY 28:9 453

fibrosis (as in rheumatoid arthritis) or a skeletal deformity (as

in scoliosis). Muscle disorders (e.g. muscular dystrophy)

resulting in respiratory muscle weakness can cause respiratory

failure and impair the ability to cough effectively. In some

cases mechanical ventilation is the most appropriate technique,

in other cases spontaneous ventilation or avoiding general

anaesthesia by use of regional or local anaesthesia may be

safer.

Positioning

Safe positioning is the responsibility of both the surgeon and the

anaesthetist. Osteogenesis imperfecta leads to easy fracturing,

� 2010 Elsevier Ltd. All rights reserved.

Malignant hyperthermia (MH)

Potentially fatal disorder of skeletal muscle that presents

during general anaesthesia.

Incidence of 1:10,000 of the population, all races are affected.

Autosomal dominant inheritance but several different

mutations identified.

Mortality has dropped to 2e3% with improved awareness and

treatment.

Caused by a loss of normal Ca2þ homeostasis at some point

along the system of excitationecontraction coupling.

Presentation

Triggered by suxamethonium (succinylcholine) and/or volatile

anaesthetics. Local anaesthetics and intravenous anaesthetics

are thought to be safe.

Most patients have one or more uneventful general

anaesthetics before the one that causes the crisis. The reason

for this is unknown.

Clinical signs are divided into two groups

C Uncontrolled muscle contraction: rigidity, masseter spasm,

hyperkalaemia, high creatine kinase, myoglobinuria.

C Metabolic storm: tachycardia, pyrexia, increased CO2 produc-

tion, metabolic acidosis.

Management

Remove triggers and convert to alternative anaesthetic tech-

nique (e.g. total intravenous anaesthesia).

Hyperventilate with 100% O2.

Stop surgery if feasible or call for extra surgical help to

conclude operation as quickly as possible.

Administer intravenous dantrolene (1e10 mg/kg) and cool

patient with ice packs and cold water lavage.

Watch for hyperkalaemia, acidosis, coagulopathy, myoglobi-

nuria and acute renal failure. Manage on intensive care unit.

Box 3

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

and the hypermobile joints associated with some collagen

disorders (e.g. Marfan’s syndrome) may become dislocated.

Corticosteroid use is associated with skin thinning and osteopo-

rosis. Rheumatoid arthritis may cause instability of the cervical

spine. Preoperative assessment should include a review of which

joint positions are most comfortable. Inflamed and painful joints

must be carefully padded and excessive pressure on small areas

avoided.

Venous access

Patients with MSD may have undergone multiple procedures

resulting in scarring and thrombosis of peripheral veins. Venous

cannulation may be made more difficult by limb deformity or

proximity to surgical site. Care must be taken when securing

intravenous cannulae to prevent pressure necrosis and skin

damage secondary to the inappropriate use of adhesive dressings.

Anaesthetic technique

Despite its attendant risks, general anaesthesia may be the

preferred option when surgery is likely to be prolonged,

SURGERY 28:9 454

significant blood loss is anticipated or the surgical site precludes

a regional technique. The residual effects of anaesthetic drugs on

respiratory function in patients with muscular disease dictate

that high-dependency or intensive care facilities may be needed

postoperatively.

A number of anaesthetic drugs require careful consideration

in specific patient groups. The depolarizing neuromuscular

blocker suxamethonium causes rapid hyperkalaemia in patients

with spinal cord injury and muscular dystrophies. In patients

with myotonia it may produce muscle rigidity and interfere with

airway control. Care must also be taken with non-depolarizing

neuromuscular blockers as their effect can be unpredictable in

patients with muscular disease.

Central neuraxial (spinal or epidural) anaesthesia has the

advantage of having minimal impact on the respiratory muscles,

where the block remains below T10, and obviates the need for

tracheal intubation (and thus neck movement). This is therefore

often the anaesthetic technique of choice for lower limb surgery.

However, accessing the subarachnoid (spinal anaesthetic) or

epidural space may be difficult in patients with spinal immobility

or following spinal surgery. Furthermore, in conditions such as

scoliosis, local anaesthetic spread is unpredictable. Blockade of

the sympathetic nerves causes widespread vasodilation, reducing

both venous return (preload) and systemic vascular resistance

(afterload) e changes that may be catastrophic in patients with

cardiac disease. In patients receiving low-molecular-weight

heparin insertion or removal of an epidural catheter, and lumbar

puncture (subarachnoid block) should be delayed until 12 hours

after the last dose, and a subsequent dose should not be given for

at least 6 hours.

Regional anaesthetic techniques, either as a conventional

‘single-shot’ block or a catheter technique to prolong the effect,

may be useful for operations involving a single limb. Used alone,

they avoid the systemic effects of general anaesthesia. When

used as an adjunct to general anaesthesia they reduce perioper-

ative opiate requirements, which is of particular benefit in those

with limited respiratory reserve.

Postoperative care

High-dependency and intensive care

When managing patients with complex multi-system diseases

preoperative planning should include identification of the most

appropriate setting for postoperative care. Patients with muscular

disease must be monitored in a high-dependency area for signs of

respiratory failure (rising respiratory rate and pCO2, falling tidal

volume and vital capacity), but in some cases a period of elective

postoperative mechanical ventilation may be appropriate.

Patients with poor respiratory function should have preoperative

multi-disciplinary review, so that risks can be discussed, the

patient can give fully informed consent and appropriate post-

operative care can be planned.

Analgesia

Pain relief can present a challenge in patients who are already

habituated to analgesics. Where possible, it is prudent to seek the

advice of the acute pain team. The general principle is to

continue any pre-existing analgesics and add further agents to

cover the perioperative period. Opiates, administered using

patient-controlled analgesia (PCA) systems, may be combined

� 2010 Elsevier Ltd. All rights reserved.

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

with ‘chronic’ oral opiates in this way. However, most PCA

systems require the patient to push a button; this may be difficult

or impossible for those with a hand deformity (e.g. rheumatoid

arthritis) or bandaging. Opiates should be avoided in patients

suffering from muscular disorders who are at risk of respiratory

depression. Local anaesthetics infused via epidural or nerve

plexus catheters may be particularly useful in these

circumstances.

Physiotherapy and mobilization

Physiotherapy will be essential for many patients both to assist

with joint mobilization and to reduce the risks of venous

thromboembolism and respiratory complications. Analgesia

needs to be adequate to cover physiotherapy and movement, not

just pain at rest.

ANAESTHESIA IN THE ACUTE BURNS PATIENT

Patients suffering a significant thermal injury should be trans-

ferred to a specialist burns unit. Surgical management will be

required in the early phase for deeper burns as wound debride-

ment and skin grafting allow faster wound closure than conser-

vative, non-surgical management. Ongoing operative procedures

may be necessary for scar revision and contracture release but

burns patients may also present to a non-specialist centre for

other types surgery and it is important to understand the unique

needs of these patients.

Airway and respiratory system

Following a burn injury, early tracheal intubation should be

considered in patients at risk of airway obstruction e those with

facial burns, singed nasal hair, carbonaceous sputum or

hoarseness. The endotracheal tube should be left uncut in case

facial swelling worsens. Circumferential chest burns may restrict

chest wall movement and escharotomies will be needed to enable

adequate ventilation.

Smoke contains a cocktail of noxious chemicals, which cause

inhalational chemical burns, in addition to the chemical

asphyxiants carbon monoxide and cyanide. Fibreoptic bron-

choscopy can identify the extent of injury and facilitate lavage of

inhaled soot. Smoke inhalation is not an indication of tracheal

intubation per se, but subsequent inflammation may lead to acute

respiratory distress syndrome (ARDS).

Resolution of the acute inflammatory changes occurs with

varying degrees of fibrotic scarring and long-term respiratory

disability may be significant. As the burn wound heals, neck

scarring and contractures may limit head and neck movement,

making tracheal intubation difficult; fibreoptic intubation can

enable safe control of the airway in this situation.

Circulatory changes and fluid balance

Major burn injuries result in rapid activation of a systemic

inflammatory response and widespread capillary leak in both

burnt and unburnt tissue. Large quantities of fluid will be

required in the early stages of resuscitation in order to maintain

tissue perfusion. Hypovolaemia and myoglobin release from

damaged muscle put the kidneys at risk of acute tubular necrosis.

Haemodynamic monitoring in the first 48 hours, or resuscitative

phase, typically reveals a picture of myocardial depression and

vasoconstriction, evolving in to one of widespread vasodilatation

SURGERY 28:9 455

and increased cardiac output in the second, post-48-hour

hyperdynamic phase.

Burn excision and harvesting of donor skin for grafting have

the potential for significant blood loss and massive quantities of

blood and clotting factors are frequently required. Older and

infected burns tend to bleed more profusely. Accurate measure-

ment of blood loss is difficult and measurement of haemoglobin

concentration and coagulation tests should be used to guide

transfusion requirements.

Microvascular changes following burn injury result in loss of

intravascular water, sodium and albumin. Ongoing electrolyte

imbalance will impact upon choice of fluid replacement and

handling of infused free water. Both invasive (e.g. pulmonary

artery catheter) and non-invasive (e.g. oesophageal Doppler

monitor) haemodynamic monitoring are routinely used to assess

volaemic status and the response to fluid administration.

Hypermetabolic response

A major burn injury is followed by a marked hypermetabolic

response; the normal basal metabolic rate of 35e40 kcal/body

surface area/hour is increased by 50% following 25% burn and

doubled where burn injury exceeds 40% burn surface area. The

development of sepsis will increase this further. Catabolism, with

nitrogen loss and lipolysis must be matched with an increased

calorie intake to prevent excessive weight loss, and periods of

starvation prior to anaesthesia must be kept to a minimum.

Nasogastric feeding may be administered overnight and intu-

bated patients may be fed in this way during surgery. Increased

calorie requirements will persist for at least a year following burn

wound closure.

Although the hypothalamic core temperature ‘set point’ is

increased by 0.03 �C for each 1% of body surface area burned, loss

of cutaneous mechanisms reduces the ability to regulate body

temperature. Loss of thermoregulation persists indefinitely in

areas of skin grafting. Thermoregulation is further impeded during

both regional and general anaesthesia, and every effort must be

made to maintain body temperature. Overhead heaters, the use of

warmed fluids for infusion and irrigation, and a high ambient

temperature and humidity are all necessary to avoid hypothermia

which, unchecked, would increase calorie requirements further.

Pharmacological changes

A reduced serum albumin concentration will increase the

unbound fraction of acidic drugs (e.g. anticonvulsants, sulpho-

nylureas) and increased a1-acid glycoprotein concentration

reduces the unbound fraction of basic drugs (e.g. local anaes-

thetics, propranolol, muscle relaxants). The increase in total

body water alters drug compartment sizes and the hypermeta-

bolic state will further alter pharmacokinetics of some drugs.

These changes may persist for months.

Muscle relaxant use is of particular interest in this patient

group. The long-acting non-depolarizing muscle relaxants have

a significantly reduced duration of action in the hypermetabolic

burn patient. Suxamethonium is a short-acting depolarizing

muscle relaxant used to assist in tracheal intubation, in particular

where difficulty is anticipated. It precipitates a marked hyper-

kalaemic response in burns patients from 2 to 3 days after injury.

The risk persists for about a year and the drug is best avoided

altogether in this population.

� 2010 Elsevier Ltd. All rights reserved.

PERIOPERATIVE MANAGEMENT OF CO-MORBID CONDITIONS

Burn patients develop a tolerance to opiates that cannot be

entirely explained by the defined metabolic changes outlined

above and frequently need massive doses for analgesic effect.

Opiate switching, for example to methadone, has been used with

some success. There is evidence to suggest that N-methyl-D-

aspartate (NMDA) receptor blockade, an effect demonstrated by

methadone, may attenuate this effect. Ketamine and gabapentin

are other useful drugs in this respect.

Other perioperative factors

Minimum monitoring for any patient under anaesthesia is rec-

ommended as including electrocardiography (ECG), blood pres-

sure, pulse oximetry, and respiratory gas analysis. This may be

difficult to achieve in a patient with a burnt chest and injured

limbs. The ECG may be obtained using fetal scalp electrodes that

hook into the chest wall and blood pressure can be measured

invasively. Pulse oximeter use can be impossible and the

anaesthetist may need to rely on blood gas analysis.

As a general rule, intravascular lines should not be inserted

through burnt tissue although avoidance may not be possible.

They are best sutured in as adhesives are unreliable on injured

skin, and frequent turning of patients will increase the risk of

inadvertent line removal.

Patient identification bands may be difficult to secure and

labelling of a ‘fixed’ piece of equipment, such as the urinary

catheter, with patient details aids positive identification prior to

procedures and blood transfusions.

Postoperative considerations

The debridement of wounds and harvesting of skin grafts induce

a considerable, additional stress response. Careful consideration

must be given to whether the patient would be best managed in

a high-dependency area postoperatively. In particular, following

facial surgery, when swelling may recur and a period of artificial

ventilation may be necessary.

SURGERY 28:9 456

Reorganization of the burn wound and nerve regeneration

means that analgesic requirements change throughout the

duration of healing for better and for worse. Following burn

wound debridement nociceptive neuronal traffic from the wound

will alter. Sites of donor skin harvest are notoriously painful.

Burns patients require a dynamic analgesic regime able to cope

with these variations. This is impossible without effective, timely

pain scoring which must be appropriate to the patient’s age and

their social and ethnic background. Paracetamol is opiate

sparing, has very few contraindications and should be consid-

ered in all patients. The non-steroidal anti-inflammatory drugs

are effective for the inflammatory nature of burn pain, yet are

contraindicated in the acute setting and following major burns

because of the increased incidence of renal complications and

peptic ulceration. Opiates are the mainstay of analgesic therapy

and should be titrated to effect.

Psychological factors

Psychological support should be offered to all patients following

a burn injury. Repeated visits to the operating theatre and

sedation for dressing changes can be very stressful. Both phar-

macological (i.e. premedication) and non-pharmacological ther-

apies can be used together to allay this. A

FURTHER READING

Allman KG, McIndoe A, Wilson IH, eds. Oxford handbook of anaesthesia.

2nd edn. Oxford: Oxford University Press, 2006.

Hines R, Marschall K, eds. Stoelting’s anesthesia and coexisting disease.

5th edn. Philadelphia: Saunders Elsevier, 2009.

Herndon D. Total burn care. 3rd edn. Philadelphia: Saunders Elsevier,

2007.

Web site: www.totalburncare.com, 2010.

� 2010 Elsevier Ltd. All rights reserved.