First do no harm: The dangers of mineral oil

CASE PRESENTATION

A three and a half year-old girl with spastic quadriplegic cerebral palsy was admitted to hospital for the investigation of increasing tachypnea and respiratory distress over a two-month period. The girl did not have a history of fever, upper respiratory tract infection, prominent cough, any obvious aspiration event or inhalation of a foreign body. She did not improve after treatment with amoxicillin or clarithromycin. Her past medical history was notable for cerebral palsy, and developmental delay secondary to prematurity and birth asphyxia. The patient was fed orally with solids and liquids, and did not have a history of recurrent cough or choking.

Physical examination revealed a chronically ill-looking, malnourished girl with a weight below the third percentile for her age. She was afebrile and tachypneic, with use of accessory muscles, and her oxygen saturation was 89% in room air. She had marked digital clubbing (Figure 1), and auscultation revealed diminished breath sounds without wheezing or crackles. Chest x-ray showed bilateral airspace disease with relative upper lobe sparing (Figure 2). Blood cultures and nasal swabs for viral antigens were negative. A radiological feeding assessment showed no evidence of aspiration, and a sweat chloride test was normal.

Further history revealed that the family had been using over-the-counter mineral oil to manage the girl’s chronic constipation. This had been administered by syringe into the girl’s mouth while she was in a sitting position, three to four times weekly over a three-month period. After obtaining this history, a computed tomography scan of the chest was performed; the scan suggested the presence of lipid within the airspaces on T1-weighted images, which is consistent with a diagnosis of lipoid pneumonia due to mineral oil aspiration.

The child required supplemental oxygen for 20 months; during that time, chronic abnormalities were evident on radiographical tests and a restrictive pattern was documented on pulmonary function tests. A gastrostomy tube was inserted one month after her initial presentation to hospital to improve her nutritional management, and her chronic constipation was managed with high fibre tube feedings and lactulose.

DISCUSSION

Chronic constipation is a very common problem in the paediatric population, and is a particularly frequent issue in the management of the neurologically impaired child. The use of mineral oil in the treatment of constipation has been well accepted because of its efficacy and infrequent side effects. Acute or chronic aspiration of mineral oil leading to lipoid pneumonitis is well documented in the paediatric and adult medical literature (1,2). Ciliary clearance is disrupted by mineral oil, and the bland nature of this compound makes it well tolerated by the airways, thus, eliciting little protective cough (3). The spectrum of disease varies widely. Deposition of mineral oil in the lung may be associated with an asymptomatic, incidentally discovered pulmonary infiltrate (4), or may lead to severe lung disease and death (5).

In the past, the diagnosis of lipoid pneumonitis has usually depended on finding lipid laden macrophages on broncho-alveolar lavage specimens or open lung biopsy (6); however, both computed tomography and magnetic resonance imaging have demonstrated specific signs of lipid infiltration of pulmonary parenchyma (7,8). These diagnostic modalities may obviate the need for more invasive procedures in the right clinical scenario, as occurred in the present case.

Treatment of lipoid pneumonitis has been supportive in nature, with retrospective case series demonstrating no benefit to the use of corticosteroids, and there is significant morbidity and mortality secondary to pulmonary fibrosis and cor pulmonale (9). Antibiotics only have a role to play in the treatment of secondary or intercurrent infections. There was a report of the successful use of whole lung lavage in one child with a more acute lipoid pneumonitis; however, spontaneous improvement has been documented in acute lipid pneumonitis when the offending agent is withdrawn (10).

This case is an addition to the body of existing literature, and serves to highlight the rare but potentially disastrous complications of an over-the-counter preparation that is used very commonly. In light of how common the problem of chronic constipation is, especially in the neurologically impaired child, there is an under-recognition of the potential problems associated with the use of mineral oil. Its use does not require a prescription and many preparations do not have a warning label relating to adverse side effects. The Compendium of Pharmaceuticals and Specialties (CPS) (11) does contain a caution relating to the possibility of fat-soluble vitamin deficiency with the prolonged use of mineral oil (even though mineral oil has been used extensively in children with cystic fibrosis and exocrine pancreatic deficiency), but the CPS does not caution against the use of mineral oil in patients with a swallowing dysfunction. The CPS also notes that “administration of a single dose at night upon retiring is usually recommended” (11), even though this practice may increase the risk of aspiration.

CONCLUSIONS

An increased awareness of the risk of aspiration, which is a potential side effect of mineral oil use, is needed among physicians and caregivers of neurologically impaired children. Recommendations could include mention of the potential risk of mineral oil aspiration in the CPS and on mineral oil packaging. Mineral oil is generally a well tolerated medication with few, uncommon side effects, but it should not be used in any patient with a potential swallowing dysfunction.