Cystic Fibrosis

The curriculum basis for this page is admittely rather tenuous, leaning on the rather generic requirement to deliver 'safe perioperative anaesthetic care to...those with significant co-morbidities including...respiratory disease'.

As such, it may be deemed rather expendable during the revision process.

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Cystic fibrosis (CF) is a monogenetic, multisystem disorder
It is characterised by chronic airways infection, exocrine pancreatic insufficiency, intestinal dysfunction and urogenital dysfunction

Autosomal recessive disease; 1 in 25 Europeans are carriers of mutated CFTR gene
Equal female and male preponderance
Incidence 1 in 1,250

Respiratory

Impaired movement of chloride extracellularly and sodium absorption intracellularly
Leads to depletion of the periciliary water layer and thickened mucus
There is subsequent failure to clear mucus, which acts as a site for bacterial colonisation and chronic infection

Pulmonary consequences of CF

Chronic pneumonia

Bronchiectasis

Recurrent mucous plugging

Mixed restrictive-obstructive pulmonary disease

Bullous disease

Pneumothoraces

Respiratory failure

Cardiovascular

Pulmonary HTN and cor pulmonale can occur

Pancreatic & hepatic

Failure to secrete sodium, bicarbonate and water in pancreatic duct
There is therefore retention of pancreatic enzymes within the pancreas itself, thus destroying pancreatic tissue
Consequent exocrine failure (in 85-90%) with:

Failure of protein and lipid absorption → chronic malnutrition, cachexia, deconditioning
Failure of vitamin A/D/E/K absorption → coagulopathy
Steatorrhoea

In time, endocrine failure due to beta cell destruction and CF-related diabetes

Hepatic features range from abnormal transaminases through to cirrhosis and portal hypertension

Gastrointestinal

Lack of chloride and thus water secretion from the intestinal epithelium leads to:

Failure of mucin flushing from the crypts
Excessive absorption of water distally within the intestine

This leads to desiccated intra-luminal contents and bowel obstruction e.g. due to tenacious meconium

GORD

Genito-urianary

Chronic lung disease and inadequate nutrition cause late onset puberty
97% of males have congenital, bilateral absence of the vas deferens
There is infertility (20% females; 95% males)

Other

Inability of sweat duct epithelia to reabsorb sodium and chloride ions leads to highly salty sweat
Chronic sinusitis
Anaemia of chronic disease
Abnormal bone mineralisation/osteoporosis due to lack of vitamin D (25%)
Depression (29%)

Symptoms

Initial presentation may be with a combination of chronic cough, (excessively) salty sweat and abdominal pain
Subsequent presentations usually relate to either infective pathology or CF complication:

Chest infections e.g. cough, green sputum, haemoptysis
Recurrent pneumothoraces
Weight loss despite reasonable caloric intake
Abdominal symptoms e.g. pain, cramps, diarrhoea, obstruction
Chronic sinusitis and nasal polyposis; 20% undergo sinus surgery at some point

Signs

Cyanosis
Clubbing
Cachexia
Acute respiratory distress

Common pathogens

Initially, e.g. during first presentation with respiratory disease, Staph. aureus, Strep. pyogenes or H. influenza

Subsequently tend to develop:

Pseudomonas
Burkholderia cepacia (if present is associated with poorer post-transplant mortality outcomes)

15% of children are diagnosed within 24hrs of birth due to the presence of meconium ileus
65% are diagnosed within the first year of life
7% of patients aren't diagnosed until they're >18yrs old

Investigations

CF patients have raised immunoreactive plasma trypsin levels

This is used for screening in the first few weeks of life via heel prick test
99% specific but >90% false positive rate

A positive chloride sweat test is unambiguous

Forearm sweating induced by pilocarpine and iontophoresis
Abnormally high sodium and chloride levels indicates CF

Delay or prevent disease progression

Promotion of secretion clearance

Physiotherapy & postural drainage with percussion/vibration
Forced expiratory technique | active cycle breathing technique
Positive expiratory pressure | flutter valve
Exercise

Medications

Inhaled DNAse to reduce secretion viscosity
Hypertonic saline to thin mucus and improved clearance; may be irritant
Acetylcysteine; does not improve lung function (and smells bad)
Bronchodilators
Corticosteroids and NSAIDs may have some benefits but usual side-effects apply
LTOT (∽6% of patients)

Control of lung infection

Antibiotics based on sputum sensitivities
May require IV anti-Pseudomonas therapy ("tune ups") as exacerbations accumulate and lung deteriorates

Ultimately, lung transplant is required (2yr survival >60%)

Attain optimal growth and nutrition

Gastroenterologist-led management aiming to prevent intestinal obstruction and attain adequate nutrition

Dietician-led nutritional assessment and advice
High calorie/fat/protein diet
Consideration for PEG feeding
Pancreatic enzyme supplements
Vitamin A, D, E and K supplements

Long-term care & psychosocial aspects

MDT approach
Regular check-ups
Prompt recognition and treatment of exacerbations
Education and support independent lifestyle
Family support

Median survival improving and now nearing 50's
>90% die from respiratory failure; liver disease and diabetes are other contributors to mortality/morbidity
Survival rates post-lung transplant:

1yr; >80%
3yr; 70%
5yr; 60%
10yr; 50%

Perioperative management of the patient with cystic fibrosis

Patients typically need surgery for:

Portacath insertion
Urological/renal surgery
Bronchoscopy ± pulmonary lavage
GI endoscopy including PEG insertion or jejunostomy
ENT surgery e.g. FESS, nasal polypectomy
Lung transplant

Overall they are at high risk of perioperative pulmonary complications

Patients are best management in a major centre with MDT input, which naturally includes their CF team
They should be optimised as much as possible prior to elective surgery, including an intensification of daily physiotherapy
Their regular medications should be continued as late as possible pre-operatively

Focussed history and examination

Existing therapies
Disease progression; severity of disease frequently correlates with bronchial hyper-responsiveness
Frequency of exacerbations and hospital admissions
Microbiological flora
Extra-pulmonary manifestations of the disease
Functional capacity

Investigations

Bloods: FBC | U&E | Coagulation| LFTs | Blood glucose
CXR: may show flattening of the diaphragm and a prominent retrosternal space in keeping with obstructive (bronchiectatic) pathology
ABG: hypoxia and hypercapnoea may predict increased risk of post-operative respiratory problems
ECG ± TTE to look for right heart strain/cor pulmonale

Spirometry

Typically an obstructive pattern
An FEV₁ <1L may indicate high risk of pulmonary complications ± need for post-operative ventilation

Functional assessment e.g. 6 minute walk test or CPET

Risk assessment

The risk of pulmonary complications are influenced largely by surgical factors, including:

Type of surgery
Duration of surgery
Surgical incisions close to the diaphragm e.g. upper abdomen, thoracic
NG tube insertion is a risk factor for post-operative pulmonary complications

Monitoring and access

AAGBI as standard
Arterial line for frequent blood gas analysis
Consider CVC ± CO monitoring in those undergoing major surgery or with cor pulmonale

GA technique

Overall, one should attempt to avoid GA where possible
Consider bronchodilator pre-medication:

Can help reduce risk of bronchospasm
May precipitate airway obstruction in 10-20% due to loss of airway smooth muscle tone

If a GA is necessary, SV on LMA may minimise detrimental effects of GA on respiratory mechanics
However, MV on ETT facilitates suctioning of secretions and better control of gas exchange
General principles which apply either way:

Avoid nasal ETT
Keep PPV pressures to minimum
Employ lung-protective ventilation
Use maximally humidified gas, bronchodilators and adequate hydration
May need to use segmental or subsegmental bronchoalveolar lavage
Avoid prolonged ventilation
Use short-acting drugs to facilitate rapid emergence

Maintenance with sevoflurane is generally preferred as:

It is not irritant (unlike desflurane or isoflurane)
It is bronchodilatory (unlike TIVA)

RA technique

May be beneficial to avoid risks of airway intervention
Their use reduces risk of post-operative respiratory depression and pulmonary infections
Can be used as an analgesic adjunct to limit use of opioids post-operatively

Verify normal coagulation parameters prior to neuraxial/regional anaesthesia

Care bundle

Careful positioning as often cachectic and osteoporotic
Normothermia using temperature monitoring
May need Microbiology input regarding appropriate perioperative antibiotic choices

Multi-modal analgesia to limit use of sedating agents
Typically require an HDU setting, especially if severe disease e.g. FEV₁ <1L
Although not typically performed as day-cases, should aim to minimise interruption of daily routine

Pulmonary support

Early extubation following full reversal of NMBA is ideal
Consider use of NIV post-operatively
Early and aggressive chest physiotherapy