First things first:
A is for Airway - Make sure his airway is open - based on your description I'm guessing this isn't an issue.
B is for Breathing - Get the guy on as much O2 as you can. Start w/ nasal cannula, and if that doesn't bring his O2 sat up to >95 go to a non-rebreather. Sit the patient up. While working on that try to make sure you've got a good pulse ox reading. If we still can't get his sats above 90% on 100% by non-rebreather he may very well need intubation and mechanical ventilation. If somebody more experienced that me wants to try CPAP they could, but if it's that bad I'd go straight to an ETT.
C is for circulation - He has a pulse bu this BP is falling. Not ready quite yet to call a code based on this alone. Between post-MI badness (like a papillary muscle rupture, re-infarct, etc) and a K of 7.6 I'm worried. Push the calcium carbonate/gluconate. Kayalexate can wait a bit as it takes too long to kick in. I'm not about to start this guy on a beta agonist now.
Now that I think he's not going to die in the next 2 minutes, I want to make sure he's in the right spot. If he's a floor patient I want to call the CCU or MICU resident/fellow and alert him/her about a possible transfer, the most pressing reason being acute respiratory failure. The cardiology fellow also needs to be called, especially if we're thinking re-infarct/evolving MI that needs urgent PCI. And if I'm an intern my senior resident need to be alerted to this patient (duh).
My working DDx:
- pulmonary edema secondary to cardiogenic shock or a ruptured papillary muscle, especially a mitral if this guy has had/is having a an inferior MI
- acute renal failure, caused by who knows what at this point (maybe secondary to cardiogenic shock, emboli, thrombosis, hypotension less likely)
- cardiogenic shock of unclear etiology, but likely suspects include papillary muscle rupture given what seems like pulmonary edema, re-infarction/new MI
Treatment to start now:
- oxygen as described above
- the typical MI stuff - ASA, heparin (I'm assuming he's been on it), a beta blocker (again, probably already on one), nitro and morphine for significant pain if I think his BP can handle it
- calcium to stabilize the myocardium, and moving on to insulin and D50 depending on what the ECG and repeat K shows.
I want to get some labs/studies, all stat:
- ABG now, repeated in 10 minutes after we get some O2 on him
- CBC
- Chem 10, especially for the K
- aPTT assuming he's been on heparin
- troponins and CK-MB now and repeated q6 hours x3
- portable chest X-ray to eval for pulmonary edema, lung processes, cardiac tamponade, heart size, any dissections
- ECHO, looking for valve function (especially mitral), estimate LVEF, amount of pericardial fluid, any regional wall motion abnormalities, and depending on what I'm thinking re: lung processes, perhaps even looking for a pneumothorax
- never heard about his temperature, would like to know if he's spiking a huge temp or very hypothermic as that could change my thinking
- review his meds - stop any negative inotropes, and re-think any renally cleared meds
Next steps depending on what my initial evaluation shows:
- further airway management, as discussed above
- if it looks like straight up pulmonary edema I'd start some diuretics, particularly the K-loosing ones like furosemide. Depending on his condition and what my physical exam showed, I might push the furosemide earlier on
- if the CXR is pretty clear and I convince myself that I didn't hear crackles, I'd have to switch from thinking about pulmonary edema to hypovolemia and begin fluid resuscitation with NS (not LR because of the K) and maybe blood depending on the CBC
- if if seems the cardiac output is too low (based on ECHO findings and BPs together with my clinical impression of whether he needs more output) I would start a pressor, most likely dopamine or norepi if his BP is low, or dobutamine if his BP is OK.
- if the BP continues to suck, think about an intra-aortic balloon pump
- assuming nothing surprising has come up, he needs the cath lab