←  Home

ICU and You

You asked

Questions sent in by readers, and the answers to them

Almost every piece on this site ends by asking you something. This is where what comes back gets published.

Some questions are answered here in a paragraph. Some turn out to deserve a piece of their own, in which case there is a link. Nobody is named unless they have said they would like to be, and a question that looks obvious to the person asking it is very often the one that half the department was also wondering about.

The questions

Showing questions from All questions  ×

No questions from this part of the site yet — yours would be the first. Use the button at the foot of the page.

August 2026 from a medical student Medical Students' Place

“One topic I would like more information on would be IO access. I've never done one in an adult or a child.”

This turned out to deserve a page rather than a paragraph, and it prompted a whole new series.

The short version: intraosseous access is the fastest reliable route into the circulation of a shocked patient, a trained person can be in the marrow in under a minute, and anything you can give intravenously can go through it at the same dose. The commonest mistake is not technique. It is waiting too long — two failed attempts at a vein, or ninety seconds without access, and you should already be reaching for it.

That you have not seen one is not unusual, and it is rather the point. It is markedly under-used in adults, largely because a generation trained before it was routine.

Read the full piece →

August 2026 from a medical student Medical Students' Place

“Also, can any medication be given subcutaneously?”

No — but a great deal more than most people assume, and the subcutaneous route is badly underestimated outside palliative care, where it is used daily and skilfully.

What governs it is absorption. Subcutaneous tissue has modest blood flow, so onset is slower and less predictable than intravenous, volumes are limited, and irritant or vesicant drugs cause local damage because they sit there. Everything else follows from that.

  • Routinely given subcutaneously — insulin, heparin and low molecular weight heparins, and, in palliative and community practice, morphine, hydromorphone, fentanyl, midazolam, haloperidol, metoclopramide, hyoscine butylbromide, ondansetron and dexamethasone, often by continuous infusion through a small indwelling cannula.
  • Fluids, too — hypodermoclysis. Isotonic fluid subcutaneously, roughly a litre over twenty-four hours per site, genuinely useful in the frail elderly or at the end of life where a drip is disproportionate.
  • Not suitable — anything needing a rapid, predictable effect; anything irritant or strongly acidic or alkaline; large volumes quickly; and most vasoactive drugs.

And the important exception. In shock, subcutaneous absorption is unreliable precisely because the body has shut down peripheral perfusion to preserve the core. A drug given subcutaneously to a shocked patient may not arrive at all — and may then arrive all at once when they are resuscitated.

So in an emergency the subcutaneous route is not a fallback for intravenous access. That is what intraosseous is for, which is a rather neat answer to your first question.

Two footnotes worth having. Adrenaline in anaphylaxis is intramuscular, not subcutaneous — the anterolateral thigh — because muscle absorbs faster and more reliably. And a handful of antibiotics, ceftriaxone among them, are given subcutaneously in some community and palliative settings, which surprises most hospital clinicians.

Ask something

What would you like explained — properly, rather than in passing?

Anything at all: a procedure you have never seen done, a drug you have always given without quite knowing why, a decision you keep having to make without a rule for it. Nothing is too basic. The questions on this page came from someone who was honest enough to say what they had not seen, and both of them were good questions.

I will answer here, or write a piece if it deserves one. Your name appears only if you ask for it.

Send me a question

The button opens a reply straight to me. If your device blocks it, write to icuandyou@icloud.com instead.