Electrical Alternans

The other day shortly into my shift we had a MET call which for the uninitiated into the TMBA (Too Many Bloody Acronyms) world of emergency health care stands for Medical Emergency Team.
One of the senior doctors and I went to the ward that called the MET and found the patient, surrounded by nurses and doctors and equipment of varying degrees of usefulness.
Harry (the ED doc) examined the poor chap, who was having great difficulty breathing, was pale and sweating profusely. I looked for an available vein to access, but I had a difficult time finding any, so Harry had a go. After a couple of tries it looked like he might need to put a central line in, but on he third try he got peripheral access in the fellows ante-cubital fossa (the inside hollow of the elbow joint)
Looking at the read out on the ecg Harry enigmatically stated he saw all he needed to see. After using a portable ultrasound to further examine the patient, he set up to put an Inter-costal catheter (or chest tube/drain) in.
We drained 3 litres of blood from the guys chest in the first 3 minutes. He was breathing easier soon. We had stat litres going to try and replace the fluid that he had lost.
I asked Harry what he had seen on the ECG, and he asked the other staff if they knew what he had seen (he's like that) When we gave a few sheepish shakes of the head he said "Electrical Alternans!" which would have been Ok if I could have remembered what that was and what it signified...but that was cool, because it seemed like the other health professionals around the bed were suffering from similar memory lapses.
Harry performed another ultrasound and we could see that the guy's heart was pumping a lot easier than was previously seen. When Harry asked me why that could be so, I stated what I thought was obvious and said "Well, there's less tamponade"
"Ah Ha!" Harry said. We all looked at the previous ECG's again and saw what we had missed before, the signs of electrical alternans and the trickle of memory from our lectures from the distant past started to flow. Electrical alternans can be an indicator of pericardial effusion. In this case the patient actually had a large heamothorax which was creating a type of tamponade (or pressure) on the heart although it was not a classic pericardial effusion, or collection of fluid, as it was not within the pericardium itself.
What does electrical alternans look like? It is often characterised by alternating larger and smaller qrs complexes on an ECG. I will chase up an example and show you. The things you learn (or relearn) on the job. I do like working with Doctor Harry, he challenges you to think.

In other news I have GONE TO THE OTHER SIDE. That's right, I a currently blogging on a mac! Sick and tired of being one of micro$oft's many beta testers I decided to see how the other half lives, or at least computes. So far the experience is good, really good. More to follow in the next few weeks months and years I am sure. My old beige box sits languishing, but I'm sure it will still get some attention as some of my favourite software still resides on it's hard disk and wont play with OS X. Most of what I want to do resides right in the box with the apple machine however so I am having fun for the moment.

Cheers all!