Haemodialysis

Haemodialysis does the work of failed kidneys. Blood is drawn from the body, passed through a filter that removes waste products and excess fluid, and returned. A session typically runs for four hours and, for a patient on a chronic programme, is repeated two or three times a week.

Our unit runs a chronic dialysis programme, takes emergency dialysis referrals, and can dialyse critically ill patients who need other organ support at the same time, because the dialysis unit and the intensive care beds are in the same place.

What happens during a session

You arrive and are weighed. The difference between your current weight and your dry weight, the weight at which your body is neither overloaded nor depleted, determines how much fluid needs to be removed during the session. Blood pressure, pulse and temperature are recorded.

Access is established, either by connecting to your fistula with two needles or by connecting your catheter. The machine is programmed with your prescription: session length, blood flow rate, dialysate composition and the fluid removal target.

For the next three to four hours your blood circulates through the dialyser. You can read, use a phone, eat if permitted, or sleep. Observations are taken every half hour, and staff are watching for the two commonest problems, a fall in blood pressure and cramping, both usually caused by removing fluid faster than the body can tolerate.

At the end, blood in the circuit is returned to you, the needles are removed and pressure applied, and you are weighed again to confirm the target was reached.

Vascular access

Dialysis needs reliable access to the bloodstream, and the type of access has a large effect on both how well dialysis works and how likely you are to get an infection.

An arteriovenous fistula, created surgically by joining an artery to a vein in the arm, is the best long term option. It has the lowest infection rate and the longest life. It takes six to twelve weeks to mature before it can be used, which is why it should be created well before dialysis is expected to start.

A tunnelled catheter in a large vein is used when dialysis is needed immediately or while a fistula matures. It works from the first day but carries a materially higher risk of bloodstream infection, so it is a bridge rather than a destination.

Look after your fistula arm. No blood pressure cuffs, no blood samples, no drips in that arm, and check daily that you can feel the thrill, the buzzing sensation that means it is flowing.

Between sessions

Most of the work of dialysis happens outside the unit. Fluid intake has to be restricted, because everything you drink between sessions has to be removed at the next one, and large gains mean uncomfortable sessions and strain on the heart.

Diet matters more than most patients are told. Potassium, which is high in bananas, oranges, tomatoes, potatoes and many Nigerian staples, can rise to levels that stop the heart between sessions. Phosphate, salt and protein all need managing, and the specifics differ from person to person. A dietary review is part of the programme, not an optional extra.

Never miss a session or cut one short because you feel well. Feeling well between sessions is what dialysis is producing, not evidence that it is unnecessary.

Emergency dialysis

Some patients need dialysis urgently rather than as part of a programme. The usual reasons are a dangerously high potassium level, fluid overload causing breathlessness, severe acidosis, uraemia causing confusion or pericarditis, and certain poisonings.

Our unit accepts emergency referrals at any hour. Referring clinicians should call ahead so that a chair, the nursing staff and the nephrologist are ready when the patient arrives.