Oedema, Ascites and the Choice of Injection Site

Decision: right femoral artery in, right femoral vein out - not the carotid.

Reasoning:

• The usual first choice, the right common carotid, sits in tissue planes that here are waterlogged. Oedematous fascia tears easily, the vessel is harder to raise cleanly, and any haematoma or incision swelling sits directly beside the face at a viewing. The neck is already thick; adding local swelling makes the presentation worse.
• The femoral triangle is a more forgiving site in a large, oedematous body. Recall the femoral sheath: from lateral to medial lie the nerve, artery, vein (and the femoral canal most medially). The artery is lateral to the vein, has a thicker wall and does not collapse; the vein is thin-walled and lies medial, containing dark blood.
• Drainage is the constraint, not injection. Ascites raises intra-abdominal pressure and opposes flow in the inferior vena cava and iliac veins. So elevate the limb 20–30 cm and tilt the table head-up to let gravity work, and expect to drain slowly and intermittently rather than freely.
• If the face does not fill and resistance climbs, convert to a multi-site approach (add the left femoral, and consider an axillary if the arms are tense) rather than raising pressure, because loose oedematous tissue extravasates at low pressures.

Decision: a stronger than usual solution delivered in a smaller than usual volume, at low pressure and slow rate.

Reasoning:

• Tissue fluid and ascitic fluid will dilute whatever reaches the capillary bed, so the effective concentration at the cell is lower than the dilution you mixed. Compensate by raising concentration, not volume - for example a 2–2.5% formaldehyde solution rather than the 1.5% you might use on a lean body.
• The tissue is already saturated. The aim is to replace fluid, not add to it. Pushing volume into an oedematous limb produces visible swelling, weeping from the mouth and nose, and a wet, shiny face that no cosmetic will hold.
• There is a competing consideration: cardiac failure means retained fluid and a high bacterial load, so preservative demand is genuinely high. That is an argument for concentration and for good drainage - not for flooding the body.
• Practical settings: keep injection pressure low (roughly 1–2 psi of hand pressure on the bulb, not a hard squeeze), run slowly, and use restricted or intermittent drainage so that a little back-pressure helps distribution without forcing fluid into the subcutaneous space.

Warning signs and the response to each:

• Progressive swelling of the face, eyelids or hands, or fluid beading at the mouth and nostrils - the classic sign of extravasation into loose tissue. Stop, reduce pressure, check that drainage is actually running; if not, clear or reposition the drain.
• Rising resistance with a pale, unfilled face - suggests a blockage, a ligated or atheromatous vessel, or that the drainage route is failing. Flush gently, then consider a second injection site rather than forcing pressure.
• Blanching or a wet, mottled patch spreading over the limb - solution tracking subcutaneously. Reduce volume and rate immediately.

What to change:

1. Switch from volume-and-pressure to concentration and time - a smaller volume of stronger solution given slowly.
2. Use regional/hypodermic injection for the face and hands if the arterial route will not carry.
3. Adjust the promise, not just the technique: tell the family honestly that the face may be fuller than expected, and advise a shorter viewing with the casket positioned so the hands are covered. Managing expectation is part of the technical decision.