This pilot study will explore sepsis recognition by North East Ambulance Service NHS Foundation Trust (NEAS), estimate the sensitivity and specificity of paramedic identification of sepsis and examine use of the Sepsis Screening Tool (SST) (See Appendix 1).
NEAS trained all clinical staff in sepsis recognition using the SST between April 2012 and March 2013 in order to improve awareness, detection and treatment of this previously ill-defined condition. Sepsis was covered in a 1-hour session, during the two-day essential annual training. The SST is based on the tool developed by the UK Sepsis Trust (UKST) and adapted locally by the North East Critical Care Network (NECCN) but has not been validated in a pre-hospital setting. The SST was updated in June 2014, in line with recommendations from the NECCN, to include oxygen saturations as a trigger of organ dysfunction. The updated version is referred to as SST+.
Background
It is estimated there are at least 100 000 cases of severe sepsis each year in the UK, although the true prevalence of sepsis may be higher due to under recognition (Cronshaw et al, 2011). Mortality from severe sepsis is unacceptably high, with 35% mortality in severe sepsis and 50% mortality in septic shock (Zeni et al, 1997; Gerber, 2010; Daniels, 2014). In the UK this equates to over 37 000 deaths annually (Cronshaw et al, 2011; Daniels, 2011) and costs the NHS over £2.5 billion (Robson and Daniels, 2013).
In the past decade there has been an international effort to standardise treatment for severe sepsis (Cronshaw et al, 2011; Marik, 2011). Despite education and awareness campaigns, sepsis recognition remains problematic and delayed recognition contributes to delayed treatment. Within the UK, Daniels et al (2011) reported that compliance to the sepsis care bundles was very poor. Recently the UK parliamentary ombudsman published Time to Act (2013) highlighting, and addressing, the failings in sepsis recognition and treatment.
Historically there has been little published on pre-hospital identification and care of sepsis (Herlitz et al, 2012) despite the fact that the ambulance service encounters large numbers of patients with sepsis. Seymour et al (2012) estimated that ambulance services encounter sepsis more often, at 3.3% of cases, than acute myocardial infarction (2.3%) or stroke (2.2%). Gray et al (2013) showed that a large proportion (88%) of severe sepsis patients arrive at hospital by ambulance. Early identification of these severely ill patients by paramedics promotes early diagnosis and treatment, which should lead to improved patient outcomes.
Wallgren et al (2014) considered pre-hospital sepsis identification and compared two screening tools with clinician judgement in a nurse-led ambulance service and found both to be superior to clinician judgement.
Travers et al (2013) described a feasibility study of sepsis diagnosis based on paramedic impression which achieved a sensitivity of 73.2% and specificity 78.9%. Erwin et al (2011) tested a simple SST with point-of-care lactate in nursing home patients transported by paramedics and found a low sensitivity for detecting sepsis or severe sepsis.
The use of various tools to improve sepsis recognition by paramedics has been described, with most following a similar structure with recognition of markers of a systemic response, identification of infection then signs of shock or organ failure. This study will investigate sepsis recognition and the use of one of these tools in a UK regional ambulance service.
Research question
How accurate is pre-hospital sepsis recognition by NEAS staff?
Aims of the study are to:
Method
A retrospective cross-sectional audit was used. A retrospective method was used to overcome issues that arise from delays accessing patient records and to ensure patient outcome data was available. A cross-sectional method (Mann, 2003) was used to capture all patients with sepsis or suspected sepsis within the study timeframe in order to allow an estimate of the sensitivity and specificity of NEAS recognition.
Sample
The sample combined patients from two sources:
These groups were combined in order to give a complete sample of patients with sepsis or suspected sepsis across the study timeframe.
Setting and timeframe
NEAS is the regional ambulance service for the North East of England. JCUH is located in Middlesbrough and covers the southern portion of the area covered by NEAS. JCUH was chosen for the following reasons:
The timeframe chosen for this study was the month of January 2014. A single month was chosen as it represented a manageable amount of data for the purpose of this pilot and due to the complete nature of the records for this month.
Data collection
Data were collected from NEAS patient report forms (paper and electronic) where any form of sepsis was suspected. Records were identified using a search tool developed by the NEAS informatics department based around the keyword of ‘sepsis’, supplemented with physical inspection of records by GM.
Data were collected from JCUH via a monthly report from the JCUH information department, providing monthly coding data on ICD code A41 sepsis supplemented by JJ ongoing audit of sepsis cases.
NHS.net was used to provide secure communications between the two organisations and Caldicott approval and necessary NHS permissions were gained from NEAS and JCUH for this audit-based project.
Definition of sepsis
Within this study sepsis and severe sepsis have been defined using the Surviving Sepsis Campaign and UKST definition. Sepsis is two or more systemic inflammatory response syndrome (SIRS) criteria plus a new or suspected infection. Severe sepsis is sepsis with organ dysfunction (Dellinger et al, 2013).
Results
Demographics
Sixty patients were identified, 68% (n=41) were male with a mean age of 69.8 years (SD 13.8, range 26–93); 48% (n=29) were identified by NEAS and 52% (n=31) were identified by JCUH.
Overall, 18% (n=11) of the original sample were excluded from the analysis. Two patients were excluded as they did not arrive by NEAS; three patients identified by JCUH and six patients identified by NEAS were unable to be traced at the other organisation.
The sample included in the analysis comprised 49 patients with a mean age of 68.5 years (SD 14.4, range 26–93) of which 67% (n=33) were male (mean age 68.9 years, SD 12.4, range 26–89) and 33% (n=16) were female (mean age 67.9 years, SD 16.8, range 40–93). These demographics are comparable with other pre-hospital sepsis studies (Seymour et al, 2012; Wallgren et al, 2014).
The JCUH diagnosis of the included patient population with regards to sepsis is shown in Figure 1.
Recognition of sepsis by NEAS
NEAS correctly recognised 18 patients as having sepsis out of 42 with a hospital diagnosis of sepsis. NEAS incorrectly labelled 6 patients as having sepsis. The sensitivity and specificity of NEAS identification is shown in Table 1.
| Patients correctly identified | Patients included in analysis | Sensitivity (%) 95% CI | Specificity (%) 95% CI | |
|---|---|---|---|---|
| NEAS identification of sepsis (sepsis documented) | 18 | 49 | 43 (28–58) | 14 (0–40) |
| NEAS identification of severe sepsis (sepsis documented + pre-alert) | 8 | 49 | 30 (12–47) | 77 (60–95) |
NEAS identification of sepsis
The classification and outcomes of patients with and without NEAS documentation of sepsis is detailed in Table 2.
| Sepsis documented by NEAS | Sepsis not documented by NEAS | |
|---|---|---|
| Patients | 24 | 25 |
| Severe sepsis at JCUH | 9 | 18 |
| Sepsis at JCUH | 9 | 6 |
| Not sepsis at JCUH | 6 | 1 |
| Requiring HDU/ICU | 4% (1/23) | 13% (3/23) |
| 3-month mortality | 21% (5/24) | 16% (4/25) |
| Mean length of stay (days) (SD, range) | 12 (14, 1–50) | 13 (16, 0.17–62) |
| Mean time to Sepsis Six in severe sepsis (minutes) (SD, range) | 205 (271,10–720)* | 120 (110, 17–450) |
The treatment and outcomes of patients with and without pre-alerting by NEAS is detailed in Table 3.
| Pre-alert by NEAS | No pre-alert by NEAS | |
|---|---|---|
| Patients | 17 | 32 |
| Identified as sepsis by NEAS | 13 | 11 |
| Destination = ED | 17 | 22 |
| High flow oxygen (100%) | 12 | 11 |
| Paramedic on scene | 16 | 21 |
| Cannulated | 63% (10/16) | 14% (3/21) |
| IV fluids (if cannulated) | 60% (6/10) | 67% (2/3) |
| Severe sepsis at JCUH | 11 | 16 |
| Sepsis at JCUH | 5 | 10 |
| Not sepsis at JCUH | 1 | 6 |
| Requiring HDU/ICU | 13% (2/16) | 7% (2/30) |
| 3-month mortality | 18% (3/17) | 19% (6/32) |
| Mean length of stay (days) (SD, range) | 16 (14, 1–50) | 11 (15, 0.17–62) |
| Mean time to Sepsis Six in severe sepsis (minutes) (SD, range) | 81 (80, 10–240) | 194 (210, 35–720) |
NEAS recognition of sepsis and use of the SST
NEAS documented sepsis in 24 cases. 67% (n=16) had ≥2 SIRS criteria documented and of these 75% (n=12) had a documented source or suspicion of infection. Six patients (10 with the additional criteria in the SST+) had ≥2 SIRS criteria, documented source, or suspicion, of infection and one or more indicators of severe sepsis.
In the 25 patients with no suspicion of sepsis recorded by NEAS, 40% (n=10) had ≥2 SIRS criteria and a documented source, or suspicion, of infection. Three (five with the SST+) had ≥2 SIRS criteria, documented source or suspicion of infection and one or more indicators of severe sepsis.
Individual criteria of the three stages of the SST were examined further and are described below.
SST Stage 1: SIRS criteria
37% (n=18) of the patients included had <2 triggering SIRS criteria documented in their pre-hospital observations; 44% (n=8) of these patients had a documented suspicion of sepsis by NEAS. 56% (n=10) of the patients with <2 pre-hospital SIRS triggers had a diagnosis of severe sepsis at JCUH and 17% (n=3) received a diagnosis of sepsis.
Temperature was recorded by NEAS in 82% (n=40) cases. The mean temperature was 37.8°C (SD 1.4, range 34.3–40.0°C). Temperature was a triggering criteria for SIRS in 45% (n=22) patients. Two patients were hypothermic (<35°C) and both displayed a raised lactate and JCUH classification of severe sepsis. Temperature >38.3°C (n=18) was always associated with a JCUH classification of sepsis (8/18) or severe sepsis (10/18). The patients identified as having sepsis by NEAS had a marginally higher mean temperature than those not identified (37.9°C versus 37.6°C). A raised temperature is an important indicator of infection (Moran, 2003; Bota et al, 2004) and is one of the SIRS criteria but clinicians need to guard against ignoring the presence of other SIRS criteria in patients who are normothermic as sepsis patients do not always present with a raised temperature.
Two patients had low white cell count (WCC, <4x109/L). Including this data would not have changed the patient's classification according to the SST. 22 patients had a high WCC (>12x109/L), 68% (n=15) already triggered for SIRS, 23% (n=5) triggered one other SIRS criteria so would have triggered for SIRS if WCC were included and the remaining 9% (n=2) had no other SIRS criteria. Mean WCC across the sample was 12.2 (SD 7.0, range 1–36.5).
SST Stage 2: sepsis criteria
The data shows chest infections are the most prevalent source of infection with urinary tract infections the second most common, combined these sources account for 71% of cases identified by NEAS and 74% of cases identified at JCUH. Abdominal pain, indwelling devices, cellulitis and chemotherapy were roughly equal in terms of frequency and no patients were identified with meningitis or recent organ transplant.
SST Stage 3: severe sepsis criteria
The need for supplemental oxygen (SST+) was the most frequent triggering criteria (available to NEAS) for severe sepsis and doubled the number of patients identified when included. The positive predictive value of the screening tool was 53% with oxygen included, compared to 44% without.
Capillary refill (CR) was the second most frequent trigger for severe sepsis. CR>2 seconds was documented in nine cases. CR was the only triggering criteria for severe sepsis in 78% (n=7, SST) and 33% (n=3, SST+) of these cases. 56% (n=5) of the patients with CR>2 were classified as severe sepsis at JCUH, 33% (n=3) sepsis and 11% (n=1) as not sepsis.
67% (n=6) patients with CR>2 seconds were recognised as sepsis cases and pre-alerted by NEAS. 83% (n=5) of these patients received the complete treatment bundle of 100% oxygen, intravenous (IV) fluids and pre-alert to receiving unit. 50% (n=3) patients were classified as severe sepsis and 50% (n=3) were classified as sepsis at JCUH.
18 patients with a JCUH diagnosis of severe sepsis were not identified by NEAS. 17% of these patients (n=3) triggered ≥2 SIRS criteria, had a documented source or suspicion of infection and one or more indicators of severe sepsis.
Lactate was not available to NEAS staff at the time of this study. Lactate was recorded by JCUH in 67% (n=33) cases. The mean lactate across the total sample was 3.0 (SD 4.2, range 0.5–24). Severe sepsis cases had a higher mean lactate (3.7, SD 4.8, range 0.9–24) than non-severe sepsis cases (1.3, SD 0.7, range 0.5–2.7). 60% of patients with a JCUH diagnosis of severe sepsis who were not identified by NEAS had a lactate of >2mmol/l.
Pre-hospital treatment
Of the 13 patients identified by NEAS as having severe sepsis, 77% (n=10) received high flow oxygen with a further 15% (n=2) receiving a lower concentration of oxygen. 92% (n=12) of these patients were attended by a paramedic, 54% (n=7) were cannulated and 38% (n=5) received IV fluids.
NEAS administered IV fluids (sodium chloride 0.9%) to 16% (n=8) of patients, all were emergencies taken to ED. In patients receiving fluids, 75% (n=6) were pre-alerted, 50% (n=4) had a BP<90 mmHg and 63% (n=5) were identified by NEAS as sepsis. All five patients identified as having sepsis by NEAS who were given IV fluids were also pre-alerted to ED and received high flow O2.
Discussion
From this study it appears that NEAS clinicians diagnose sepsis and severe sepsis without using the SST to support their decision making. The lack of uniformity between NEAS diagnosis of sepsis and what is indicated by the SST supports the assertion that the SST is not being used consistently. Consistent use of the SST would improve the recognition of sepsis and increase the accuracy of identification. Recognition of sepsis continues to be problematic for NEAS so it is paramount that education around sepsis continues.
The use of electronic media to record patient information and support clinical decision-making should lead to higher levels of screening and sepsis identification (Nguyen et al, 2014). One system which has the potential to work in this way is the National Early Warning Score (NEWS) (Royal College of Physicians, 2012), which can aid with sepsis screening (Corfield et al, 2013; Keep et al, 2015).
At present NEAS staff can't measure all the criteria on the SST. It appears that access to WCC would improve the ability of the SST to identify a small number of patients with SIRS. The inclusion of point-of-care lactate would appear to greatly improve the ability of pre-hospital clinicians to identify organ dysfunction as an indication of severe sepsis (Younger and McClelland, 2014). In terms of identifying severe sepsis, it appears that the inclusion of the additional oxygen based criteria in the SST+ is justified and in line with international consensus definitions.
The sensitivity of NEAS staff in identifying severe sepsis falls within the range of values reported elsewhere with sensitivity values from 16.9% (Wallgren et al, 2014) to 47.8% (Guerra et al, 2103). This study found a higher rate of sepsis identification than reported by Wallgren et al, which may be due to the education and research on sepsis within NEAS in recent years.
When paramedics accurately identify and pre-alert severe sepsis patients it appears to decrease the time to completion of the Sepsis Six in hospital (Tables 2 and 3). Paramedic treatment of severe sepsis, when it is identified, is still inconsistent and shows little improvement from previous studies in NEAS (McClelland and Younger, 2013). Paramedic use of IV fluids to treat patients with severe sepsis is an area needing further consideration. The presence of hypotension (BP<90 mmHg) in the pre-hospital setting consistently triggers aggressive treatment by paramedics, including fluids. The diagnosis of severe sepsis does not consistently trigger the same response. Missed opportunities to administer IV fluids in severe sepsis have been reported elsewhere (Seymour et al, 2010). It is the authors' opinion that there is still considerable variance in when to administer IV fluids in the pre-hospital setting stemming from the historic use of a BP<90 mmHg as the main triggering criteria for fluid administration and changes in fluid resuscitation of trauma patients.
Strengths and limitations
This study is a pilot study using data from a single site with a limited timeframe and the data presented is largely descriptive due to the pilot nature of this study and the small sample. This limited scope does not allow conclusions to be drawn about the wider region, seasonal variations or changes over time. The data that is presented is largely descriptive due to the limitations of the small sample and the scope of the project. The inclusion of a statistician in the research team would allow a larger data set to be analysed using more powerful techniques.
The audit of any aspect of pre-hospital care relies on the ability to link to patient outcomes that are often held by Trusts other than the ambulance service and this has proven difficult in the past. The patients excluded from the analysis would need to be considered and appropriately dealt with in a larger study, as would any other missing data.
This study has linked pre-hospital and in-hospital data which can, and should, be used to feedback to staff and promote reflective learning. One barrier to reflective learning in pre-hospital care is that paramedics rarely discover if their diagnoses were correct. Data, such as is presented here, could be used to educate staff but it would need to be delivered in a timely fashion.
The retrospective method used means analysis is limited by the documentation. The format that some of the observations are recorded in limits their usefulness, e.g. capillary refill is recorded as either normal or above 2 seconds. The retrospective application of the SST may not be representative of what would happen in practice if the paramedic had the SST to hand as part of their decision making based on the complete clinical picture.
Expanding on this pilot study
This pilot study has shown that it is possible to audit and track sepsis patients from pre-hospital care into hospital in order to examine the impact of pre-hospital identification. Expanding this study to include multiple hospitals across the region and running over an extended timeframe to control for seasonal variations would give a comprehensive picture of pre-hospital sepsis recognition in the North East.
In one month using a single hospital NEAS identified 24 patients with sepsis. NEAS currently identify around 250 patients per month across the whole region as having sepsis. Based on these figures it is anticipated that a regional study would include up to 500 patients per month. This figure appears low compared to the estimation of Seymour et al (2012) that 3.3% of EMS encounters involve sepsis. This would indicate nearer to 900 cases per month for NEAS.
During the study both authors received mixed reports from pre-hospital and in-hospital staff describing good and bad experiences of delivering sepsis care. A future consideration would be to conduct a qualitative study into the thoughts and perceptions of both groups of staff in order to identify areas of good practice, areas where care could be improved and the reasons why the SST is not being used.
Conclusions
Consistent use of the SST would improve the ability of NEAS staff to identify patients with sepsis. The SST supports and aids clinician decision making but relies on the initial suspicion of sepsis and the decision to use the tool. The addition of oxygen saturations to the screening tool improves its ability to detect patients with severe sepsis and therefore justifies the inclusion of the extra criteria. The treatment delivered to severe sepsis patients identified in the pre-hospital setting is inconsistent and more staff training and resources are required to improve care in this area.