Hypertonic Saline for Cystic Fibrosis
Answer: B
Cystic fibrosis (CF) involves a chloride channelopathy in exocrine tissues – it is a multi-organ system disease, involving impaired lung function, pancreatic insufficiency and diabetes mellitus, hepatobiliary disease and cirrhosis, bone disease, and genitourinary disease. Pulmonary complications account for over 90% of the morbidity and mortality in CF patients.
CF demonstrates a spectrum not only in terms of organ systems involved but also in severity of disease burden in the individual patent. For this reason the emergency department evaluation should include pointed questioning about the child’s frequency of illness, strength of cough, amount of sputum produced, airway reactivity, history of recovery from illnesses, and a thorough review of systems. A review of current therapies and recent acceleration of treatment may reveal the child’s current trajectory of disease.
Younger children with CF have more reactive airways, which may respond to β–agonists. It is important to note, however, that older children may have worsening expiratory airflow with the use of bronchodilators. This is due to the progressive damage to cartilaginous support in the lower airways; chronic bronchial muscle hypertrophy may in fact help to “stent” the airways open. In these patients, bronchodilators may result in “floppy” lower airways, and impaired gas exchange. A careful history and reassessment regarding response to β–agonists are important to anticipate and avoid complications (B).
Hypertonic saline provides a high osmolar solution to hydrate inspissated mucus by drawing water from the airway to improve the aqueous surface layer that is deficient in CF. Various studies have shown an improvement in mucus clearance, lung function, and symptom scores in children over 6 years of age.
N-acetylcysteine cleaves disulfide bonds in mucus glycoproteins; it has been shown to liquefy sputum from CF patients in vitro. Although thought to be a mucolytic agent, there is little evidence of its in vivo efficacy. Unfortunately NAC can also induce bronchospasm and airway inflammation. Its unproven efficacy, potential deleterious side-effects, and odor make it a less attractive alternative (D).
Other therapies with better evidence include inhaled DNase (cleaves strands of DNA left behind by degenerating neutrophils – “clears the debris”), chest physiotherapy (breathing/”huffing” techniques promote clearance or external percussion to clear secretions), and antibiotics (provide anti-microbial and inherent anti-inflammatory effects).
This child should be treated for his reactive airways disease and be carefully evaluated for early pneumonia. After an observation period with improving signs and symptoms, an appropriate outpatient strategy includes coordination of care, ensuring proper hydration, and strict return precautions.
In addition to acute exacerbations and worsening lung infections, children with CF are at risk for apical blebs (up to 3.4%) that may cause spontaneous pneumothorax (A). Although this complication should be at the forefront of the clinician’s mind, this normotensive child with bilateral breath sounds, no chest pain, and slow-onset worsening symptoms is unlikely to have a pneumothorax – he is stable enough to await confirmation.
Given his normal oxygenation and generally well appearance, emergent intubation is unlikely to be needed at this point. A careful observation period will reveal how he responds to acute therapy (C).
References
Fitzgerald, M. and D. Ryan, Cystic fibrosis and anaesthesia. Continuing Education in Anaesthesia, Critical Care & Pain, 2011. 11(6): p. 204-209.
Gibson, R.L., J.L. Burns, and B.W. Ramsey, Pathophysiology and management of pulmonary infections in cystic fibrosis. Am J Respir Crit Care Med, 2003. 168(8): p. 918-51.
Ratjen, F. and G. Doring, Cystic fibrosis. Lancet, 2003. 361(9358): p. 681-9.
Cystic fibrosis (CF) involves a chloride channelopathy in exocrine tissues – it is a multi-organ system disease, involving impaired lung function, pancreatic insufficiency and diabetes mellitus, hepatobiliary disease and cirrhosis, bone disease, and genitourinary disease. Pulmonary complications account for over 90% of the morbidity and mortality in CF patients.
CF demonstrates a spectrum not only in terms of organ systems involved but also in severity of disease burden in the individual patent. For this reason the emergency department evaluation should include pointed questioning about the child’s frequency of illness, strength of cough, amount of sputum produced, airway reactivity, history of recovery from illnesses, and a thorough review of systems. A review of current therapies and recent acceleration of treatment may reveal the child’s current trajectory of disease.
Younger children with CF have more reactive airways, which may respond to β–agonists. It is important to note, however, that older children may have worsening expiratory airflow with the use of bronchodilators. This is due to the progressive damage to cartilaginous support in the lower airways; chronic bronchial muscle hypertrophy may in fact help to “stent” the airways open. In these patients, bronchodilators may result in “floppy” lower airways, and impaired gas exchange. A careful history and reassessment regarding response to β–agonists are important to anticipate and avoid complications (B).
Hypertonic saline provides a high osmolar solution to hydrate inspissated mucus by drawing water from the airway to improve the aqueous surface layer that is deficient in CF. Various studies have shown an improvement in mucus clearance, lung function, and symptom scores in children over 6 years of age.
N-acetylcysteine cleaves disulfide bonds in mucus glycoproteins; it has been shown to liquefy sputum from CF patients in vitro. Although thought to be a mucolytic agent, there is little evidence of its in vivo efficacy. Unfortunately NAC can also induce bronchospasm and airway inflammation. Its unproven efficacy, potential deleterious side-effects, and odor make it a less attractive alternative (D).
Other therapies with better evidence include inhaled DNase (cleaves strands of DNA left behind by degenerating neutrophils – “clears the debris”), chest physiotherapy (breathing/”huffing” techniques promote clearance or external percussion to clear secretions), and antibiotics (provide anti-microbial and inherent anti-inflammatory effects).
This child should be treated for his reactive airways disease and be carefully evaluated for early pneumonia. After an observation period with improving signs and symptoms, an appropriate outpatient strategy includes coordination of care, ensuring proper hydration, and strict return precautions.
In addition to acute exacerbations and worsening lung infections, children with CF are at risk for apical blebs (up to 3.4%) that may cause spontaneous pneumothorax (A). Although this complication should be at the forefront of the clinician’s mind, this normotensive child with bilateral breath sounds, no chest pain, and slow-onset worsening symptoms is unlikely to have a pneumothorax – he is stable enough to await confirmation.
Given his normal oxygenation and generally well appearance, emergent intubation is unlikely to be needed at this point. A careful observation period will reveal how he responds to acute therapy (C).
References
Fitzgerald, M. and D. Ryan, Cystic fibrosis and anaesthesia. Continuing Education in Anaesthesia, Critical Care & Pain, 2011. 11(6): p. 204-209.
Gibson, R.L., J.L. Burns, and B.W. Ramsey, Pathophysiology and management of pulmonary infections in cystic fibrosis. Am J Respir Crit Care Med, 2003. 168(8): p. 918-51.
Ratjen, F. and G. Doring, Cystic fibrosis. Lancet, 2003. 361(9358): p. 681-9.