The impact of intra-operative transoesophageal echocardiography on cardiac surgical practice.

The use of transoesophageal echocardiography during cardiac surgery has increased dramatically and it is now widely accepted as a routine monitoring and diagnostic tool. A prospective study was carried out between September 2004 and September 2007, and included all patients in whom intra-operative echocardiography was performed, 2 473 (44%) out of a total of 5 591 cases. Changes to surgery were subdivided into predictable (where echocardiographic examination was planned specifically to guide surgery) and unpredictable (new pathology not diagnosed pre-operatively). A change in the planned surgical procedure was documented in 312 (15%) cases. In 216 (69%) patients the changes were predictable and in 96 (31%) they were unpredictable. The number of predictable changes increased between 2004-5 and 2006-7 (8% vs 13%, p = 0.025). In these cases, intra-operative echocardiography was specifically requested by the surgeon to help determine the operative intervention. This has implications for consent and operative risk, which have yet to be fully determined.

Transoesophageal echocardiography (TOE) in the operating room.

Perioperative transoesophageal echocardiography (TOE) was introduced from cardiology into cardiac anaesthesia in the 1980s. Initially TOE was used mainly as a monitor of left ventricular ischaemia, but now provides real-time dynamic information about the anatomy and physiology of the whole heart. TOE is of value in the management of patients undergoing procedures including cardiac valvular repair, surgery for endocarditis, surgery of the thoracic aorta, and may contribute useful information in a wide range of cardiac pathology. It is also useful in guiding therapy in haemodynamically unstable patients in the operating room and the intensive care unit. TOE is relatively cheap and non-invasive, but it should not be used as a stand alone device but as a tool which provides data in addition to the data acquired from other forms of monitoring. The use of TOE carries not only the benefits of a rapid and effective investigation, but also risks associated with the procedure itself and the burden of providing training and experience for practitioners. The establishment of TOE in perioperative cardiac anaesthetic care has resulted in a significant change in the role of the anaesthetist who, using TOE, can provide new information which may change the course and the outcome of surgical procedures.

Vecuronium and atracurium infusions during hypothermic cardiopulmonary bypass.

Two similar groups of patients undergoing coronary artery bypass grafting received either atracurium or vecuronium infusions for neuromuscular blockade. Both groups demonstrated a marked reduction in neuromuscular blocking requirements during hypothermic bypass at 30 C. The ratio of the dose rates at 30 C to that at 37 C was significantly less with vecuronium (p less than 0.01).

A method for producing normocarbia during general anaesthesia for caesarean section.

Twenty-six patients were anaesthetised for Caesarean section using the Bain anaesthetic system for intermittent positive pressure ventilation. There was an inverse relationship between maximum end tidal carbon dioxide tension and the fresh gas flow (FGF) to the system. A significant difference existed between the patients receiving 80 ml/kg/min FGF and those receiving 120 ml/kg/min. Estimated carbon dioxide levels in the pregnant term patient were higher at each FGF rate than the levels reported in non-pregnant patients by other workers. In order to maintain maternal arterial carbon dioxide tension at or close to the normally quoted term value of 4.1-4.4 kPa, when using positive pressure ventilation with a Bain system, a fresh gas flow rate of at least 120 ml/kg body weight/minute is required.