Tuesday, 9 January 2007

The Hidden Pneumonia

The following case has been anonymised to safe guard patient confidentiality which is the prime importance of all doctors for their patients. However, there are important points to be drawn from the following scenario, which is as follows:

A very elderly man was admitted to another hospital with a chief complaint of fever, breathing difficulty and reduced conscious level-- it was sad because he was so ill.

He had suffered from a right sided stroke last year and was nursed flat and fed by nasogastric tube at home.

He was unable to give the resident any history, so as is commonly the case, the family or carers are the only ones to give a history if any at all.

In this case, the family mentioned that the patient had developed 'breathing difficulty' and his conscious level had decreased.

On admission, the patient was febrile (40 degrees C), shocked with a low blood pressure, tachycardia and his consciousness was decreased. His skin was very dry, JVP was not raised. Heart sounds were normal. His oxygen sats were 96% on nasal cannula oxygen, respiratory rate 24/min. Auscaultation revealed some fine right sided crackles, but left sided examination revealed course 'wet' crackles at the base and mid zone.

ABG revealed a compensated respiratory alkalosis and hypoxaemia on room air.

Clinically, this patient had a left sided pneumonia and dehydration.

Bloods revealed severe dehydration (Na 165, BUN 70, Creat 0.67), a normal white cell count but a high CRP >13. Urine analysis showed 3+ bacteria.

Such severe dehydration can occur due to the sweating phase component of fever, raised metabolic rate from infection, and also NG feeds can add to the problem as they contain standardised solutes which do not take into account the changes in body requirements, as in this case when water replenishment would have been of better advantage.

The junior resident rightly considered a urinary tract infection as a cause of infection and therapy was commenced for that. However, on first inspection, the Chest Roentogen (CXR) looks relatively normal for an elderly patient-- until you take a second look.

However, there was consolidation
BEHIND the heart shadow-- a hidden pneumonia. In any case, the history from his family and his physical examination provided the salient diagnostic clues. The Chest Roetogen is not there to make the diagnosis, it is taken to aide in the formation of a diagnosis.

If at first you do not see, look again, and stand back from the Xray. Unfortunately, on the above picture, the streaky consolidation which is evident on the CXR has not shown up particularly well.

When inspecting a CXR always look in areas that your eye would normally ignore, such as behind the heart, below the diaphragms, as pneumonias can be lurking in those places. Things that are usually missed on Xray are inspection of the ribs (looking for fractures / destruction from cancer), the clavicles, shoulder joints and scapulae-- all important structures. Moreover, the thoracic spine is also very important on a chest Xray, which is usually missed as well.

Don't just look at the lungs and the heart borders-- that is not inspecting an Xray in detail-- it is just the beginning. Also, don't forget to check the patient name!!

One final note of warning, patients being fed with an NG tube in a recumbent position may be predisposed to aspiration of their feed and hence, these 'at risk' patients should be nursed at an incline such that gravity will not allow for feed to regurgitate up the oesophagus and cause aspiration-- of course, never say never, it can still occur despite these measures.

Instructing the nursing staff to nurse these patients at an incline is a MUST and not to lie them flat and this also goes for patients with Cardiac failure and Respiratory Disease, in which patients, can become easily short of breath....but that is for another blog entirely, and I shall touch upon this area again in the future.

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