S64 Understanding better the pathophysiology of aspiration pneumonia
Background Aspiration of oropharyngeal or gastric contents into the lower airways can cause a number of syndromes including chemical and bacterial pneumonia, although the pathophysiology of each entity is different.1 Data from Dr Foster's Guide and our local coding department revealed a high incidence and mortality from aspiration pneumonia alerting us to study those patients.
Methods Retrospective analysis of 53 patients coded as aspiration pneumonia from February 2010 to March 2011. Analysis of presentation, investigations, management, pre-disposing factors and outcome was undertaken.
Results Average Age 78, M/F ratio (1:1). Out of 53 coded as aspiration pneumonia, 2 were re-coded to an alternative diagnosis. Out of 51 patients, 36 died (71%) and 15 survived but 17/51 (23%) had chest x-rays which were not suggestive of aspiration pneumonia. Of the 36 patients that died, 67% showed positive x-ray changes, while the 15 survivors had 80% x-rays suggesting pneumonia. Abstract S64 table 1 shows the list of clinical presentations and potential risk factors. On average each patient had 4 out of the 7 clinical features positive. 23/51 (45%) had either a basic swallow or SALT assessment of whom only 2/23 (9%) passed. 0/51 (0%) proceeded to mechanical ventilation. 51/51 (100%) had oxygen, intravenous fluids and antibiotics.
Conclusion Aspiration pneumonia has a high mortality, particular in those with a history of aspiration living in residential or nursing facilities. 23% of patients with a good clinical history of aspiration did not show x-ray changes to suggest pneumonia. It may suggest a difference in the pathophysiology of lung injury in these patients who aspirate acidic gastric contents causing a chemical injury without x-ray changes of pneumonia. Although the treatment at present is no different, research needs to be incorporated into guidelines to diagnose, prevent and treat the different types of aspiration.