Intended for healthcare professionals

Feature Christmas 2013: Aggravations

Tied up in science: unknotting an old anaesthetic problem

BMJ 2013; 347 doi: (Published 11 December 2013) Cite this as: BMJ 2013;347:f6735
  1. Clemens R M Barends, anaesthetics registrar ,
  2. Anthony R Absalom, professor of anaesthesia, consultant anaesthetist
  1. 1University Medical Centre Groningen, Department of Anaesthesiology, Groningen, Netherlands
  1. Correspondence to: C R M Barends clemensbarends{at}

Like death and taxes, Clemens Barends and Anthony Absalom show that knots are an immutable fact of life. Acceptance rather than anger is therefore the mature response

Why does every anaesthetic procedure involve a trail of lines and tubes resembling spaghetti? Apart from the frustration this mess generates, it can also be detrimental to patient safety. Monitoring equipment can become undone, intravenous drips can be removed, and endotracheal tubes can become dislodged. Is it carelessness to allow this situation to occur and do we have to apologise at handovers for such a mess? How do these knots arise despite our attempts to prevent them? Studies of knots by mathematicians, physicists, and statisticians provide a reassuring answer.


Topology and knot theory describe how knots can only be formed by a line crossing under and then over itself. A circle can never create a true knot as there are no loose ends for a crossover to occur. Creating a …

View Full Text

Log in

Log in through your institution


* For online subscription