suggested guidelines. Secondly, the ACC ⁄ AHA guidelines state that a patient with uncontrolled systemic hypertension (minor clinical predictor) without compromised heart function or signs of coronary heart disease can generally proceed safely with a scheduled operation for low risk surgery [1]. Thirdly, the 'drastic' fall in blood pressure in our patient occurred in the surgical ward without any intervention and therefore was most likely due to a reduction in pre-operative anxiety. The signs of left ventricular hypertrophy were quite mild and without evidence of left ventricular strain. The signs of chronic hypertensive heart disease were not evident on echocardiography. Fourthly, the fluctuating blood pressure and unstable haemodynamics in theatre and, possibly, the signs of left ventricular hypertrophy were due to the thyroid storm, and not an underlying chronic cardiac condition or so-called 'white-coat' hypertension. The aforementioned ACC ⁄ AHA guidelines do not mention thyroid function in preoperative risk assessment and our case report was a timely reminder. Finally, the operation was postponed and performed later after treatment of the thyroid storm.

The Triservice Anaesthetic Apparatus was designed around 30 years ago as a robust and highly portable anaesthesia delivery system for medical support to airborne operations and it has been the core anaesthesia system for the Defence Medical Services since then. Over this period there have been a number of equipment changes but issues remain which are in part mitigated by recent training developments. This article reviews these changes and developments and considers the future of this equipment.• Minimal reliance on compressed gases and electrical supplies • Robust • Compact and portable • Simple to operate • Able to withstand climatic extremes • Easily maintained and serviced • Economical in use • Versatile in the use of volatile agents • Versatile with regard to patient age/size group.bmj.com on July 6, 2015 -Published by