What’s New in the Patient Safety World

January 2014

It MEOWS But Doesn’t Purr



We’ve done several columns on early warning systems or scores using physiologic parameters to help identify patients with early clinical deterioration (see list at the end of today’s column). Most have been used in adult medical/surgical populations and have utilized the MEWS (modified early warning score) or in pediatric populations utilizing PEWS (the pediatric early warning score).


In the UK a modified early obstetric warning system (MEOWS) has been used in obstetric inpatients to track maternal physiological parameters, and to aid early recognition and treatment of clinical deterioration after recommendation by the 2003–2005 Confidential Enquiry into Maternal and Child Health report (Lewis 2007).


MEOWS tracks the following parameters:

·        temperature

·        blood pressure

·        heart rate

·        respiratory rate

·        oxygen saturation

·        conscious level

·        pain scores


Trigger thresholds are set for “red” (most serious) and “yellow” (somewhat less serious) triggers and algorithms describe what responses are indicated for each type trigger. The MEOWS was subsequently validated in 676 consecutive obstetric adminssions at one UK hospital (Singh 2012). 30% of the patients triggered and 13% had morbidity, which included things like haemorrhage, hypertensive disease of pregnancy, and suspected infection. The MEOWS was 89% sensitive and 79% specific, with a positive predictive value 39% and a negative predictive value of 98%. The authors suggest that MEOWS is a useful bedside tool for predicting morbidity. They attributed the high sensitivity to the fact they used morbidity rather than mortality or ICU admissions as their primary end point because the latter are relatively rare in obstetric populations (in fact, there were no admissions to the intensive care unit, cardiorespiratory arrests or deaths during their study period). They suggest that adjustment of the trigger parameters may improve positive predictive value.


So MEOWS has been used in UK obstetrical settings for about a decade now. A recent study, however, has called into question its practical usefulness, impact on workload, and overall adherence (Mackintosh 2014). The Mackintosh study actually provides excellent insight into the contextual, cultural, hierarchical, organizational and practical barriers to implementing EWS programs. They did interviews and chart reviews on maternity wards at 2 UK hospitals, both of which presumably had guidelines which included use of the MEOWS. At one hospital the MEOWS chart was used in only 22% of postnatal cases.


The authors point out that a big barrier was lack of a sound evidence base for MEOWS and fact that it was often perceived as being foist upon staff by outside forces for “political” and economic reasons despite lack of demonstration that it actually improved outcomes. Many staff apparently felt that MEOWS might have some value in high-risk cases but that it was of little value in the much more prevalent “healthy” pregnancies and deliveries. It was felt that the potential gains from MEOWS in this “healthy” population would likely be small. Many of the midwives felt that it resulted in a number of unnecessary interventions and took away some of their autonomy and clinical judgment.


A major problem at one of the hospitals was that even when the algorithm called for the midwives to “call a doctor”, those doctors often either did not respond or did not listen to the midwives. Lack of timely responsiveness by such physicians obviously is a significant barrier to implementation of a system like MEOWS that requires escalation of care based upon physiological triggers.


Part of the problem also had to do with workload and efficiency. Midwives might be required to enter vital signs in up to 4 separate places.


Interestingly, they found that obstetrical units were often treated differently by the organization than med/surg units, a feeling often embraced by the obstetrical units themselves.


As an aside, both the Mackintosh and Singh papers make mention of respiratory rate being a vital sign often incompletely monitored. Given our numerous columns on the hazards of opioid-induced respiratory depression, one might argue that respiratory rate could be extremely valuable in detecting patients at risk of clinical deterioration in a population of patients who may be receiving opioids.


There were, however, some positive impressions of the MEOWS program. Many staff commented on how the MEOWS charts made things like vital signs visually apparent, compared to previously being “hidden” in the medical record, and hence making it easier to see trends. And they were able to cite individual cases where early recognition of deterioration likely provided interventions necessary to prevent adverse outcomes.


The Mackintosh paper could really be a sociology paper about change management in general since so many of the barriers noted are encountered almost any time we look to change the way things are done. But the insights point out that despite the MEOWS concept being “simple” and “intuitively attractive” one needs to look hard at the evidence base and demonstrate that it actually improves outcomes, not just creates more work. (Note that studies like the Singh study demonstrated that MEOWS can identify patients at risk of deterioration but was not designed to show that implementation of MEOWS improved actual patient outcomes). Programs where we can clearly demonstrate a positive impact after implementation are much easier to maintain. Some very good lessons here!



Some of our other columns on MEWS or recognition of clinical deterioration:


·        February 26, 2008 “Nightmares: The Hospital at Night

·        April 2009 “Early Emergency Team Calls Reduce Serious Adverse Events

·        December 15, 2009 “The Weekend Effect

·        December 29, 2009 “Recognizing Deteriorating Patients

·        February 22, 2011 “Rethinking Alarms

·        March 15, 2011 “Early Warnings for Sepsis

·        October 18, 2011 “High Risk Surgical Patients

·        March 2012 “Value of an Expanded Early Warning System Score

·        September 11, 2012 “In Search of the Ideal Early Warning Score

·        May 2013 “Ireland First to Adopt National Early Warning Score

·        September 17, 2013 “First MEWS, Now PEWS








Lewis G (ed.) Saving Mothers’ Lives: Reviewing maternal Deaths to make Motherhood Safer 2003–2005. The Seventh Confidential Enquiry into Maternal Deaths in the United Kingdom. London: CEMACH, 2007




Singh S, McGlennan A, England A, Simons R. A validation study of the CEMACH recommended modified early obstetric warning system (MEOWS). Anesthesia 2012; 67(1): 12–18 Article first published online: 9 NOV 2011




Mackintosh N, Watson K, Rance S, Sandall J. Value of a modified early obstetric warning system (MEOWS) in managing maternal complications in the peripartum period: an ethnographic study. BMJ Qual Saf 2014; 23(1): 26-34 Published Online First: 18 July 2013 doi:10.1136/bmjqs-2012-001781








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