654 British Journal of Plastic Surgery

doi: 10.1054/bjps.2001.3690

Effective insulation of the cutting diathermy blade

Sir, To reduce blood loss and the subsequent need for transfusion, many plastic surgeons use cutting diathermy, particularly when dissecting a large surface area. When the surgery is performed through a relatively small incision, there is a risk of diathermy burns to the skin edge.

To reduce this risk, many surgeons attempt to insulate the proximal end of the cutting blade. The commonest methods are to use Steristrips (3M Healthcare) wrapped around the proximal end of the blade, or plastic suction tubing through which the blade is passed. Tubing can also provide a means of smoke extraction if suction is applied, but it is bulky and may be unwieldy to handle. Both methods are time-consuming and depend on the skill and dexterity of the scrub nurse or surgeon for their effectiveness.

Neither paper nor plastic provides a reliable method of insu- lation. Rubber is a much more effective insulator against the passage of electricity. We have observed that a size 10 French Jaques/Nelaton catheter (Rusch) fits snugly over the cutting diathermy blade (Fig. 1). It is quick and simple to apply, cheap and readily available. It does not add significant bulk, so there is no alteration in the handling characteristics of the cutting diathermy. Its effectiveness is not dependent on the scrub nurse's dexterity. Being rubber, it provides better more effective insulation.

Until the manufacturers produce shorter cutting blades, surgeons will continue to devise methods of insulating the prox- imal end to avoid iatrogenic thermal injury and the complica- tions and litigation that can result. We, like others, 1 recommend the use of rubber as insulation. A Jaques/Nelaton catheter is simpler and more effective than the alternatives we have tried.

Yours faithfully,

Giilian D. Smith MB, BCh, FRCSEd, Specialist Registrar in Plastic Surgery Jeremy Roberts MA, MB, MS, FRCS, Consultant Plastic Surgeon

Department of Plastic and Reconstructive Surgery, New Surgical Development Block, City General Hospital, Newcastle Road, Stoke on Trent ST4 6QG, UK.

R e f e r e n c e

1. Nichter LS, Goldstein LJ, Bush AM, Reinisch JE Sloan GM. A sim- ple method for preventing misplaced electrocauterization. Plast Reconstr Surg 1987; 80: 307.

doi: 10.1054/bjps.2001.3671

New technology for interactive teaching

Sir, We have used a digital projector and 'white board' as a teaching aid for joint case review, preoperative planning, outpatient follow-up and peer-review audit.

A Mitsubishi LCD digital projector (LVP-X300U) was ceil- ing mounted in our departmental conference room to project an image onto a wipeable 'white board'. The connections allow images from either a laptop computer or a desktop computer to be projected onto the 'white board'. This enables the easy view- ing of digital images taken in clinics and wards in both Nottingham City Hospital and peripheral hospitals.

As part of the unit teaching, trainees were asked to make differential diagnoses and plan incisions and flaps to recon- struct defects by drawing directly onto the 'white board' over the projected image, 1 using the pen as a 'two-dimensional scalpel' (Fig. 1).

Difficult management cases were discussed jointly with other consultants, and surgical options were planned and

Figure 1--Rubber catheter insulation to diathermy blade. Figure 1--The digital LCD projector (1) and the 'white board' (2).

Short reports and correspondence 655

discussed on the 'white board'. Slides could, of course, be used in a similar way, but the immediate availability of digital images has obvious advantages.

Yours faithfully,

R. M. Haywood MBBS, FRCS, Specialist Registrar A. G. B. Perks FRCS(Plast), FRACS, Consultant Plastic Surgeon

Department of Plastic, Reconstructive and Burns Surgery, Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PB, UK.

Reference

1. Millard DR. Make a plan, a pattern, a second plan. In Millard DR, ed. Principalization of Plastic Surgery, 1st ed. Boston: Little, Brown and Company, 1986: 266.

doi: 10.1054/bjps.2001.3655

The effect of elevation on digital blood pressure

Sir, We read with interest the article by Khan et al 1 and would like to offer some comments. We think that the study was concise and showed valuable data regarding the drop in mean arterial pres- sure with elevation. However, these data were obtained from normal subjects; replanted and revascularised digits may behave

differently because there is no vasomotor control, so one would not expect a drop in mean arterial pressure with elevation.

The study makes the assumption that blood pressure is pro- portional to blood flow and tissue oxygenation, but this is not the case according to Poiseuille's law (Q=nprn/8ql, where Q is the flow in cm 3 sec l, p is the pressure gradient in dyne cm 2 r is the radius in cm, 7"/is the viscosity in dyne sec cm -2 and l is the length in cm), which shows the relative contribu- tions of the various determinants of flow3 It is evident that even small changes in calibre result in marked alterations in flow, since flow is proportional to the fourth power of the radius.

It should be noted that the metabolic requirement of a replanted digit is a lot less than a muscle flap and therefore a drop in blood pressure may not affect the outcome.

Finally, if a limb is not elevated after surgery then a more marked swelling will develop, which can compromise circulation)

Yours faithfully,

Beryl A. De Souza BSe, MPhil, FRCS, Registrar M. Shibu FRCS, FRCS(Plast) , Consultant Plastic Surgeon

Department of Plastic Surgery, The Royal London Hospital, Whitechapel, London E1 1BB, UK.

References

1. Khan IU, Southern S J, Nishikawa H. The effect of elevation on digi- tal blood pressure. Br J Plast Surg 2001; 54: 137-9.

2. Ganong WE Dynamics of blood and lymph flow. In Review of Medical Physiology, 11 th ed. Lange Medical Publications, 1983.

3. Matsen FA III. Compartmental syndrome. An unified concept. Clin Orthop 1975; 113: 8-14.