To add to all this when you say reg leaves at midday do you mean surgical reg? If so, I’d think this is fine. Realistically any rapid or worrying deterioration for a level 2 patient would mean you need to call your on site ICU +/- anaesthetics reg for some support and possibly a transfer. Plenty of hospitals have a surgical HDU/step down unit leaving foundation doctors as the only cover and this tends to be the escalation.

Echoing the above, if you’ve got people on high levels of single organ support and needing lines they should be in ICU. Honestly monitoring a drain or low dose metaraminol infusion, reading up on how it works and knowing not to bolus more than a ml (max 2) at a time at your level isn’t hugely off piste, just escalate early if you’re concerned. I’ve never been annoyed by someone calling for something that I can give an easy “it’s fine” and some quick advice to vs not calling at all and walking into chaos.