Case Study
A low-risk nulliparous woman at 30 weeks’ gestation presented to the delivery suite at 11 p.m. complaining of abdominal pain, fever, and vaginal blood loss. Her initial observations were heart rate 125 beats/min, blood pressure 100/60 mmHg, respiratory rate 28 breaths/min, oxygen saturation 98 percent on air, and core temperature 40.1°C. After midwifery and junior obstetrician assessment, routine bloods and cultures were taken. Vaginal examination revealed “bulging” membranes, noted to be “very warm” to touch. An ultrasound scan confirmed an intrauterine death; this was considered secondary to a presumed diagnosis of chorioamnionitis.
The decision to labor was made by the senior obstetric registrar, and assisted rupture of membranes (ARM) occurred at 1:00 a.m. Heavily blood-stained liquor and a cervical dilatation of 6 cm were noted. At 3:10 a.m., spontaneous vaginal delivery of a stillborn male fetus occurred. IV antibiotics were administered an hour after ARM, and IV fluids were running at 125 ml/h.
At 3:30 a.m., the parturient’s observations were heart rate 130 beats/min, blood pressure 87/60 mmHg, and temperature 38.2°C, with no recorded values for respiratory rate or oxygen saturation. At 7:30 a.m., she remained tachycardic and hypotensive. After further review following a shift changeover, her persistent tachycardia and borderline urine output prompted arterial blood gas analysis. This revealed a raised lactate level of 2.8 mmol/liter, and subsequent care was escalated to an obstetric high-dependency area, invasive blood pressure monitoring, and aggressive fluid management. This process was managed by the consultant anesthetist and obstetrician and facilitated by the senior midwife.
The parturient’s physiologic status slowly improved over the day, and she subsequently made a full recovery. Blood cultures grew group B streptococcus, and placental histology later demonstrated florid chorioamnionitis. Her Modified Early Obstetric Warning Score (MEOWS) chart is shown in Figure 14.1.
Figure 14.1 Reproduction of the parturient’s MEOWS chart
Key Points
Parturients may present with severe sepsis, where time-critical assessments, investigations, and treatments are crucial in preventing morbidity and mortality.
The Modified Early Obstetric Warning Score (MEOWS) chart enables early identification of deterioration as well as changing trends and guides appropriate escalation in care.
Inaccurate and incomplete recording of physiologic observations can seriously delay prompt intervention.
Admission observations may reveal physiologic triggers such as a “red” heart rate and temperature, “yellow” systolic blood pressure, and a “yellow” respiratory rate.
In this case, the first 8 hours displayed a distinct lack of blood pressure readings, almost no respiratory rate or oxygen saturation documentation, and a persistent tachycardia. It was not until the morning, with a changeover of staff, that she received the appropriate senior level of care.
The importance of the early warning score chain of action and its four essential steps should be highlighted.
The first tracks the physiologic parameters, and when they fall outside the normal ranges, a clinical response is triggered.
An escalation policy should state whom to call, how urgently they should respond, and appropriate interventions.
The final step analyzes the intervention effectiveness and correction of the physiologic derangement. This process is underpinned by education, training, and audit, without which the chain will fail.
Discussion
Early warning scores (EWSs) were introduced to aid detection of early deterioration in general medical patients in the belief that they may lead to a reduction in deaths, cardiac arrests, and unanticipated critical care admissions. In 2007, the National Institute of Health and Care Excellence (NICE) recommended that physiologic “track and trigger” scoring systems be used for monitoring all patients in acute care settings.1 They identified six key physiologic parameters one or more of whose deviation from normal could generate a risk score. These vital signs were respiratory rate, oxygen saturation, heart rate, systolic blood pressure, temperature, and consciousness level.
Such track and trigger systems can be categorized as single parameter, multiple parameter, aggregate weighted, or a combination.2 Single-parameter systems will trigger on one extreme observation value, and although they are simple to use, they do not permit risk stratification and a graded response. In multiparameter and aggregate-weighted systems, a score is obtained by adding together weighted values of abnormal vital signs. This permits charting of progress with time and/or intervention and enables classification of patients into low, medium, or high risk and their appropriate graded response.
Obstetric EWSs
Using these systems in obstetrics has proved challenging because those designed for adult medical patients may be considered unsuitable primarily because of changing physiology during pregnancy. However, the NICE recommendations apply the recording of vital signs to all acute admissions, including obstetrics. Despite lack of good evidence and validation, national organizations have recommended EWS use in obstetrics.3–5
The recommended MEOWS chart, based on the Stirling Royal Infirmary chart, permits a graphical display of specific calling criteria and their trigger points via a color-coding, parameter-based EWS. This is a simple visual display whereby a “red” or two “yellows” suggests that the parturient’s condition is worsening, triggering escalation of clinical intervention. The MEOWS chart records six vital signs: respiratory rate, heart rate, systolic and diastolic blood pressures, oxygen saturation, and temperature. It also records secondary observations such as proteinuria, lochia, pain scores, and whether the parturient looks subjectively unwell. Values within an arbitrarily agreed “normal” range fall into white squares, “mildly abnormal” observation values into yellow squares, and “abnormal” observations into red squares.
Practicalities of EWSs
The importance of accurate and complete documentation cannot be overemphasized. As highlighted in the Case Study, the actual value for respiratory rate and oxygen saturation must be written down in the correct color-coded box. A rate of 28 breaths/min was wrongly documented in the “normal” zone, and as a consequence, this early trigger was missed. Clearly marked points connected by straight lines must be used for heart rate, blood pressure, and temperature to highlight trends. The lack of respiratory rate recordings is problematic because this is one of the most sensitive indicators of serious morbidity.6 If MEOWS does trigger, the unit’s escalation policy must be adhered to. Of concern in this case was the lack of early anesthetic/critical care involvement and early senior input toward the management of sepsis and the critically unwell patient. This is particularly pertinent in severe sepsis, where rapid patient deterioration and death can ensue. The parturient triggered on several parameters at the initial assessment but without clinical escalation, and this may have led to further deterioration without intervention. The classic stepwise deterioration (rising heart rate and falling blood pressure in sepsis) was not evident, but instead, there was the constant maintenance of a high EWS trigger score. This is not unexpected in young, fit patients, who often can maintain their functional reserve despite abnormal vital signs until eventually reaching a point of critical and rapid deterioration.
Current Problems in Practice
Clinical validation of any obstetric EWS system is necessary to demonstrate improved outcome. A study in a tertiary center reviewed 676 consecutive obstetric admissions, analyzing their completed EWS charts and notes for evidence of morbidity.7 Two hundred parturients (30 percent) triggered and 86 parturients (13 percent) experienced morbidity according to predefined criteria. The study found that the MEOWS chart was 89 percent sensitive and 79 percent specific, with a low positive predictive value of 39 percent. The authors concluded that the MEOWS chart is a useful bedside tool for predicting morbidity and suggested adjustment of trigger parameters to improve positive predictive value. However, there is evidence of limitations of MEOWS in women with chorioamnionitis or other serious infections during pregnancy.8
Recent UK surveys of lead obstetric anesthetists and heads of midwifery have revealed intriguing insights into the use of such charts in practice.9, 10 Although fewer than half the respondents use the Confidential Enquiry into Maternal and Child Health (CEMACH)–recommended chart, several use a slightly modified version. There is widespread interhospital variation in the type of EWS and thresholds for escalating care but good agreement between anesthetists and midwives regarding the top six physiologic parameters to be included in any obstetric EWS. There are also differing opinions as to exactly which women need an obstetric EWS.9
The more subjective assessments of a woman’s health status by a midwife should not be overlooked. Concerns of midwives, patient partners, and relatives have been highlighted to be of importance.10 An ethnographic study provides excellent insight into the contextual, cultural, and practical barriers to implementation of MEOWS into clinical practice.11 Many healthcare professionals felt that MEOWS might have some benefit for high-risk women but that it was of limited value in “normal, healthy” pregnancies and deliveries. Midwives also felt that it led to a number of unnecessary interventions and limited their autonomy and judgment. Staffing pressures, lack of support for EWSs, and limited education and training are considered to be the three biggest barriers.9
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