Role of Multimodal Monitoring (MMM) in the Perioperative Period: Improving Outcomes in High Risk Surgical Patients

Abstract

The early 1980s saw radical advances in perioperative monitoring. In a relatively short period of time, the “finger on the pulse”, manual measurement of blood pressure using Riva Rocci cuff, aneroid mercury column and listening for Korotkov sounds with a stethoscope and (if you were lucky) a primitive ECG machine were replaced from the early to mid 1980s with pulse oximetry, automated non-invasive BP, end tidal carbon dioxide and anaesthetic agent monitoring and sophisticated ECG technology. This was a major transition in monitoring technology but, since then, progress has been halted. From the late 1990s technology has become widely available to measure the extent of anaesthesia induced cortical suppression using EEG monitoring technology (e.g. BIS, Medtronic, USA), cerebral and tissue oxygenation using the Invos cerebral oximeter (Medtronic, USA) and various flow monitors using Doppler and arterial pulse waveform analysis from the radial or femoral artery lines. In 2011 NICE (National Institute for Health and Care Excellence, UK) guidelines were introduced advocating the use of flow monitoring and then in 2012 “depth of anaesthesia” in high-risk surgical patients. Although widely available this technology is still only used in a small percentage of patients in the UK. Recent evidence indicates that the introduction of flow monitoring alongside existing monitoring does not radically improve outcome in terms of reduction in complications and has no effect on 30 day and in-hospital mortality, which remains at around 5 % in the elderly, high risk surgical population. This is probably due to a fundamental misunderstanding of circulatory physiology which has led to protocols and interventions using flow monitoring which are inappropriate. Often they result in massive fluid and sodium overload. This is particularly a problem in the highest risk patients. The rapid rise in the number of such patients has I believe necessitated a radical re-evaluation of circulatory physiology under anaesthesia and its implication for management. Using the combination of these new monitoring technologies (flow, depth of anaesthesia and cerebral and tissue oximetry) in a multimodal monitoring strategy provides maximum benefit by reducing complications, the necessity for high dependency care and mortality. This combined strategy and its rationale is the subject of this chapter.