We thank Watkinson and Tarassenko for the interest they have taken in our review on patient surveillance.1 

We are in agreement that in their cited work, they tested mandated five-channel physiologic monitoring versus  standard care,2and that extra monitoring with Biosign™ (OBS Medical Ltd., Abingdon, Oxon, United Kingdom) had no effect on adverse event rates or mortality, which we had summarized as patient outcome. As we pointed out in our review, the study of measuring the impact of patient surveillance or continuous monitoring is challenging.

In addition, we also agree, as described in our review, that deterioration detection must move beyond the use of just static alarm threshold to optimize the balance between “true” and nuisance alarms. In their mentioned recent study of their Biosign ™ monitor in a step-down unit,3use of the device decreased the authors' cardiorespiratory instability criteria without changing the rate of medical emergency team (MET) activations. In our own work,4we consider a reduction of MET calls a success, a sign of an intervention that happened at an earlier stage of deterioration and therefore prevented a physiologic derangement that necessitated a MET activation. But, if on the other hand, monitoring is used to trigger MET alerts, an increase in activations may be a desirable outcome.

At Dartmouth, all medical and surgical patients are now continuously monitored; we have a physiologic database containing more than 3 million hours of patient physiologic data and more than 20 trillion individual data points of inpatient oxygen saturations and heart rates. Like the Oxford research group, we have seen little variation across patient groups. What we have seen is a hospital-wide reduction of MET alerts and transfers to the intensive care unit: between 10–67% depending on the unit.

The research done at Oxford, Pittsburgh, and other locations is outstanding: more pieces are being added to solve the puzzle of patient surveillance, and our patients benefit.

Taenzer AH, Pyke JB, McGrath SP: A review of current and emerging approaches to address failure-to-rescue. ANESTHESIOLOGY 2011; 115:421–31
Watkinson PJ, Barber VS, Price JD, Hann A, Tarassenko L, Young JD: A randomised controlled trial of the effect of continuous electronic physiological monitoring on the adverse event rate in high risk medical and surgical patients. Anaesthesia 2006; 61:1031–9
Hravnak M, Devita MA, Clontz A, Edwards L, Valenta C, Pinsky MR: Cardiorespiratory instability before and after implementing an integrated monitoring system. Crit Care Med 2011; 39:65–72
Taenzer AH, Pyke JB, McGrath SP, Blike GT: Impact of pulse oximetry surveillance on rescue events and intensive care unit transfers: A before-and-after concurrence study. ANESTHESIOLOGY 2010; 112:282–7