http://www.diva-portal.org This is the published version of a paper published in Critical Care Research and Practice. Citation for the original published paper (version of record): Schollin-Borg, M., Nordin, P., Zetterström, H., Johansson, J. (2016) Blood Lactate Is a Useful Indicator for the Medical Emergency Team. Critical Care Research and Practice, : 5765202 http://dx.doi.org/10.1155/2016/5765202 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Permanent link to this version: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119091 Hindawi Publishing Corporation Critical Care Research and Practice Volume 2016, Article ID 5765202, 7 pages http://dx.doi.org/10.1155/2016/5765202 Research Article Blood Lactate Is a Useful Indicator for the Medical Emergency Team Maria Schollin-Borg,1 Pär Nordin,2 Henrik Zetterström,3 and Joakim Johansson1,4 1 Department of Anesthesiology and Intensive Care, Ostersund¨ Hospital, 83183 Ostersund,¨ Sweden 2Department of Surgical and Perioperative Sciences, UmeaUniversity,90185Ume˚ a,˚ Sweden 3Department of Surgical Sciences, Anesthesiology and Critical Care Medicine, Uppsala University, 75185 Uppsala, Sweden 4Department of Surgical and Perioperative Sciences, Anesthesiology and Intensive Care, Unit of Research, Education and Development-Ostersund,¨ Umea˚ University, 83183 Ostersund,¨ Sweden Correspondence should be addressed to Maria Schollin-Borg; [email protected] Received 30 November 2015; Revised 2 February 2016; Accepted 7 February 2016 Academic Editor: Samuel A. Tisherman Copyright © 2016 Maria Schollin-Borg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Lactate has been thoroughly studied and found useful for stratification of patients with sepsis, in the Intensive Care Unit, and trauma care. However, little is known about lactate as a risk-stratification marker in the Medical Emergency Team- (MET-) call setting. We aimed to determine whether the arterial blood lactate level at the time of a MET-call is associated with increased 30-day mortality. This is an observational study on a prospectively gathered cohort at a regional secondary referral hospital. All MET-calls during the two-year study period were eligible. Beside blood lactate, age and vital signs were registered at the call. Among the 211 calls included, there were 64 deaths (30.3%). Median lactate concentration at the time of the MET-call was 1.82 mmol/L (IQR 1.16–2.7). We found differences between survivors and nonsurvivors for lactate and oxygen saturation, a trend for age, but no significant correlations between mortality and systolic blood pressure, respiratory rate, and heart rate. As compared to normal lactate (<2.44 mmol/L), OR for 30-day mortality was 3.54 ( < 0.0006) for lactate 2.44–5.0 mmol/L and 4.45 ( < 0.0016)forlactate> 5.0 mmol/L. The present results support that immediate measurement of blood lactate in MET call patients is a useful tool in the judgment of illness severity. 1. Introduction We could not find earlier studies where lactate levels have been studied in patients who are the subject of a Medical The level and clearance ratio of blood lactate are well-known Emergency Team- (MET-) call. as useful parameters in the diagnosis and prognosis of the The Medical Emergency Team is a concept first estab- septic patient [1–4]. In a mixed Intensive Care Unit (ICU) lished in Australia around 1995 [10] and since then has spread setting, there is strong evidence for a correlation between to a large number of countries. The term used to describe high lactate levels and increased mortality [1, 5]. The dynamic the system varies and includes Rapid Response Team or progress of hyperlactatemia over the first 24 hours following Critical Care Outreach. There may be slight differences in ICU admission is a significant and independent determinator how the system works, but the purpose is the same: early of illness severity in a mixed ICU-cohort [6] similar to recognition of patients at risk, avoidance of ICU care if findings in septic patients. adequate, reduction of cardiac arrests, and reduction of in- It has also been shown that lactate correlates with mor- hospital mortality. tality in unselected patients at the emergency department The aim of the present study was to explore relations (ED) [7] including older patients (>65 years) admitted with or between blood lactate levels at the time of a MET-call and withoutsepsis[8]anditwasrecentlysuggestedtobeincluded illness severity. We hypothesized that the blood lactate level as a triage tool [9]. wasassociatedwithanincreasedriskof30-daymortality. 2 Critical Care Research and Practice 2. Material and Methods The cohort was stratified in different lactate intervals, roughly based on the quartiles, for analysis of a possible 2.1. Study Design and Setting. This is an observational study correlation between mortality and level of blood lactate. on a prospective and consecutively gathered cohort of MET- To further explore the impact of hyperlactatemia, we patients where concentration of arterial blood lactate at divided the cohort in four groups based on presence of MET-calls during two years was registered. The study was hyperlactatemia and acidosis. Mortality was calculated in performed at the regional secondary referral hospital of these different groups. Ostersund,¨ Sweden, having a catchment area of approxi- mately 126 000 inhabitants. 2.4. Statistical Analysis. We divided the whole cohort of Thehospitalhas250generalbedswithanannualturnover patients into two groups; survivors and nonsurvivors at 30 of approximately 20 000 patients, and a mixed ICU with 8 days from the MET-call. beds and 600 admissions per year. The overall in-hospital The Mann-Whitney test was used to compare numeric mortality is around 2%. variables, such as lactate concentration, vital signs, and length The study was approved by the Regional Ethics Review of hospital stay between the groups. A two-tailed value Board in Umea.˚ less than 0.05 was chosen as limit for significance, but, The MET system has been employed at Ostersund¨ Hospi- to compensate for multiple comparisons, the Bonferroni correction was used in the univariate analyses, giving a tal since 2007, covering all adult somatic wards. Our Medical = 0.0083 Emergency Team consists of one intensive care physician and corrected level of significance (for the six different one intensive care nurse and is available 24 hours per day, tests in univariate analysis). Data are presented as percentage, seven days a week. The physician with primary responsibility median, and interquartile range (IQR). for the patient and the nurse on the ward are also important Odds Ratios (OR) for mortality in the groups with lactate 2.44–5.0 and ≥5.0 mmol/L were calculated with the group members of the team assembled around the patient. The < annual MET-call rate varies from 70 to 120. Our MET is 2.44 as a reference. not called to a cardiac arrest since there is another team Sensitivity, specificity, positive predictive value (PPV), responsible for cardiopulmonary resuscitation. and negative predictive value (NPV) for 30-day mortality werecalculatedforthetwocut-offlevelsof2.44and5.0. Any nursing staff on the ward can make the MET-call Confidence intervals were calculated with the Wilson score when predefined MET criteria are fulfilled, usually after method. contact with the physician responsible (though this is not a We further analyzed the relationship between the inde- prerequisite). Our hospital uses a slightly modified version pendent variables age, blood lactate, and oxygen saturation of the Early Warning Scoring (EWS) system, first described (i.e., the parameters with < 0.05 in the univariate analyses) in 1997 [11]. Our criteria for a MET-call comprise any of the and the outcome measure 30-day mortality in a multiple following: systolic blood pressure <90 mmHg, heart rate <40 logistic regression. or >130 beats/min, respiratory rate <8or>30 breaths/min, Analyses were carried out using Statistica 12 (Statsoft®, peripheral oxygen saturation (SpO2) <90%, and sudden Tulsa, OK, USA). decrease in consciousness and/or intuition/serious concern for the patient. It is defined that we shall always see the patient within 30 minutes from the call. 3. Results and Discussion During the study period 227 patients were the subject of 2.2. Patients. All patients who were the subject of MET- MET-call and hence eligible for inclusion. Sixteen patients call between March 2012 and March 2014 were screened for were primarily excluded for reasons described in Figure 1. eligibility, regardless of age and comorbidity. Patients were 227 MET-call patients in this study reflect the usual excluded only if a blood lactate was unavailable. calling rate for our hospital when compared to the years preceding. Ninety-three percent of cases had a lactate mea- 2.3. Data Collection. Patient demographics (age, gender), surement result suggesting that our findings may be applied vital signs (systolic blood pressure, heart rate, respiratory to MET-call patients in general. Age, gender, and referral rate, and peripheral oxygen saturation), and the reason for ward are reported in Table 1. the MET-call were collected from records kept at the time The median age of our patients was high, 78 years, of the call. Lab results, comorbidity, the event of transfer