Shock Index in the Acute Care Geriatric Patient and its Correlation to the Need of a Life Saving Intervention?
Batsheva Tzadok1, Stav Soffer2, Shay Shapira2*, Sandra Bushnak1 and Eran Tal Or1
1Baruch Padeh Medical Center, Poriya Israel
2Bar Ilan Faculty of Medicine, 8 Henrietta Szold Street, Tzefat Israel
*Address for Correspondence: Shay Shapira, Bar Ilan Faculty of Medicine, 8 Henrietta Szold Street, HaKarmel 7, Kfar Yona 4033453, Israel, Tel: +972-528-973-430; E-mail: Shay_Shapira@yahoo.com
Submitted: 20 November 2018; Approved: 04 January 2019; Published: 08 January 2019
Citation this article: Tzadok B, Soffer S, Shapira S, Or ET. Shock Index in the Acute Care Geriatric Patient and its Correlation to the Need of a Life Saving Intervention. Int J Gerontol Geriatr Res. 2019;2(1): 001-004.
Copyright: © 2019 Tzadok B, 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
Five-level triage is the gold standard in Emergency Departments (ED) worldwide; the Emergency Severity Index (ESI) and Canadian Triage and Acuity Scale (CTA) are the leading systems. The accuracy of these systems is in question with respect to the aging population. We examined Shock Index (SI) and Age-Adjusted Shock Index (AASI) as well as traditional vital signs such as Blood Pressure (BP) and Heart Rate (HR) in patients above age sixty-five. We investigated their association to the need for a Lifesaving Intervention (LSI) or mortality (mort) within 48 hours of presentation to the ED.
This retrospective study examined medical files of patients aged sixty-five and above who presented to the ED during 2015-2017 and were then hospitalized in a medical ward or intensive care unit. We then dichotomized them into two groups, those who required an immediate life-saving intervention and/or mortality within 48 hours (LSI/mort), and those who did not. We searched for a correlation between the need for these interventions/mortality with HR, BP, SI, and AASI.
Using T-test we found a positive correlation between SI and AASI and the need for an LSI/mort. In the non-LSI group, the mean SI was 0.59 compared to 0.66 in LSI/mort group (p = 0.033). AASI mean value was 46 non-LSI compared to 52 with LSI (p = 0.027). In contrast, we found no correlation between HR, systolic blood pressure, and age for prediction of LSI. In the patients who died within 48 hours we found a strong association of elevated SI and AASI. Those who died had a mean SI of 0.83 in contrast to 0.60 in the no mortality cohort (p = 0.004). AASI had a comparable trend: 72 for those with mortality and 47 who survived (p = 0.001).
Our findings support the assertion that there is a need to reconsider which vital signs we use for elder patients within our emergency triage algorithms. We also believe there is a place to consider the incorporation of SI and AASI into ED triage of elder patients.
Patients aged 65 years and above account for approximately 20% of Emergency Department (ED) presentations, a number that is expected to rise substantially in the coming decades. The delivery of timely acute care to this vulnerable population will be an increasingly larger challenge in the future; therefore, it is important to optimize our triage tools [1,2].
Physiological and pathological changes of aging may alter homeostatic capacity. A tachycardia might not develop since sympathetic response to stress is reduced and a hypotensive response may be difficult to detect in the elder population, where hypertension is prevalent . The manifestation of such in the triage vital signs of the aging ED population inspired our study.
“Triage” refers to the methods used to assess patient acuity and assignment to the appropriate place of care and treatment. It is an essential factor in proper function of emergency departments. A five-level triage is the gold standard in EDs worldwide. Triage algorithms such as the Canadian Triage and Acuity Scale take into account vital signs of heart rate, O2 saturation, respiratory rate, systolic blood pressure, fever, and Glasgow coma scale . Emergency Severity Index, another popular triage system, considers the vital signs of heart rate, respiratory rate, and oxygen saturation and resources needed [5-8]. There are five classes of urgency in these triage algorithms: one is resuscitation, two is emergent with a high risk of deterioration and a time critical problem, three is stable with need of multiple resources, four and five are less urgent and non-urgent, respectively.
In the Emergency Department (ED) appropriate triage may have a direct effect on mortality. The geriatric patient population has a higher percentage of severe illness and injury than any other age group [9,10]. The impact of growth of this group will be in ED overcrowding with a potentially sicker patient population , making the subject of triage in this vulnerable population of paramount importance.
Not many studies have examined the performance of the triage algorithms on the elderly population. In 2010 Platts-Mills et al. studied the accuracy of the Emergency Severity Index (ESI) triage system for identifying elder ED patients 65 years and above receiving an immediate life-saving intervention and found it to have a sensitivity of only 42% .
Current triage systems may not only err in the use of traditional vital signs, they are often difficult to perform in their entirety. The measurement of respiratory rate is an example of such. Respiratory rate, a known predictor for bad outcomes is a relatively burdensome and time-consuming measurement for triage purposes. It is frequently estimated and not measured directly, or completely omitted from vital signs measurement .
Shock index has shown superiority to traditional vital signs in predicting severity of illness . Shock Index (SI), defined as Heart Rate (HR) divided by systolic blood pressure, has been shown to be predictive of mortality in trauma and pneumonia [15,16], predicting uterine rupture during pregnancy , risk stratification of myocardial infarction, and severity of hypovolemic shock [18,19]. An SI measurement of above 0.7 in the elderly is pathological . Age Adjusted Shock Index (AASI), when SI is multiplied by age, has been shown in some studies superior to SI in predicting mortality and the need for a Life-Saving Intervention (LSI) [15,21].
This combination of factors, known physiological alterations of vital signs in the elder population, the challenges of performing effective triage in the elder population, and the known value of SI for predicting disease severity, drove us to examine SI and AASI as well as traditional vital signs HR and BP at triage in the ED and its association with LSI and mortality within 48 hours in elderly medical patients.
Materials and Methods
We conducted a single site retrospective study of medical patients aged 65 and above during 2016 and 2017 admitted to the Baruch Padeh Medical Center via the ED to the Internal, Cardiac, and/or intensive care wards. The Baruch Padeh Medical Center-Poriya is a 300-bed hospital in Tiberius, Israel with 76,000 ED visits a year and a twenty-six percent admission rate. Fourteen percent of the ED patients are over sixty-five and fifty percent of these elder patients are admitted.
The patients were separated into two groups, those with an LSI intervention or mortality within 48 hours, and those without. The patients’ triage score and vital signs were recorded, including Heart Rate (HR), Blood Pressure (BP), SI, and AASI.
Life-saving interventions included1. Airway and breathing support, including intubation or emergent noninvasive positive pressure ventilation. 2. Procedures: electrical therapy, including defibrillation, emergent cardioversion, or external pacing, pericardiocentesis. 3. Hemodynamic support, including significant intravenous fluid resuscitation in the setting of hypotension. 4. Emergency medications, including naloxone, dextrose, Atropine, Adenosine, or vasopressors.
The files of three-hundred and twenty-one patients above the age of sixty-five were examined. Eleven patients were excluded from the study because they arrived to the ED mechanically or non-invasively ventilated. Fifty-four patients of the group studied had an LSI/mort while two-hundred and fifty-six patients did not.
Using T-test we found a positive correlation between SI and AASI and the need for an LSI/mort. In the non-LSI group, mean SI was 0.59 compared to 0.66 in LSI group, p = 0.033. AASI mean value was 46 in the non-LSI group compared to 52 with LSI, p = 0.027.
In contrast we found no significant difference in HR, BP, and age between those with an LSI/mort and those without. In the intervention group the mean age was 78.4, in the intervention group it was 76.5. In addition, using Pearson correlation we found no correlation of age and SI measurements and no added benefit of AASI to SI (Table 1).
We examined BP, HR, age, SI, and AASI with respect to different subgroups of intervention. The airway intervention subgroup showed no significant relation with SI and AASI, yet it did show a difference with respect to HR (81 bpm vs. 97 bpm, respectively; p = 0.015). In contrast, the group with PTCA showed no significance with respect to HR, SI, or AASI (Table 2).
Seven patients in the cohort population died within forty-eight hours. In this group there was a statistical difference between SI and AASI between those with and without mortality. Those who died had a mean SI of 0.83 in contrast to the no mortality cohort 0.60, p = 0.004. AASI had a similar trend of those with and without mortality: 72 and 47, respectively; p = 0.01. There was a statistical difference between diastolic blood pressure in the no mortality to mortality group 75 vs. 61, p = 0.029. HR showed a limited statistical difference with 81 and 98, respectively, p = 0.06 (Table 2).
Triage in the ED is an entity that requires re-evaluation; traditional vital signs that we depend on for detecting severity of disease often fail us in the elderly population .
In addition, current triage systems use respiratory rate, a problematic vital sign. Due to the time consumption of counting respiratory rate it is often omitted or roughly estimated, affecting the application of triage scores .
Our study examined patients admitted to the hospital with and without LSI within 48 hours. We examined HR, BP, SI, and AASI and their correlation with need for LSI and/or mortality.
Overall, we found correlation with SI and AASI but not with HR and BP. The mean value for those with an LSI was 0.66, which is similar to current literature for an abnormal finding in geriatric populations .
In our study different subgroups of interventions and mortality showed different trends with respect to variables measured. The twenty-three patients who underwent PTCA had few differences between the intervention vs. non-intervention group. Only diastolic BP showed a significant difference, with a higher diastolic blood pressure in the PTCA intervention group (81.4 mmHg versus the non-PTCA group 81.3 mmHg; p = 0.044). It is of note that for acute coronary syndrome the most important tool is the electrocardiogram for detecting acute ischemia rather than the triage score by ESI or CTA.
Patients with airway intervention showed no significant association between airway intervention with respect to SI or AASI. There was a significant association with heart rate between those who had airway intervention and those who did not (81 bpm vs. 97 bpm, respectively; p = 0.015). Our postulation for this finding is that there was a large proportion of airway patients with pulmonary edema in whom elevated blood pressure is a common finding, thus lowering the SI and AASI despite the relative rise in HR.
In the group of patients who died within 48 hours we found both SI and AASI to be significantly higher. It is of note that AASI showed a stronger trend of association to mortality than SI alone (72 and 47, respectively; p = 0.01). Systolic blood pressure had no significant correlation. This is a small group of patients yet it shows a trend that merits further assessment.
We as healthcare workers place a great emphasis on blood pressure and heart rate. They are part of the ESI and Canadian Acuity Score as well as secondary triage criteria such as SIRS criteria and QSOFA criteria for sepsis and ABC score for massive transfusion. With the aging of our patient population we may see changes in trends of vital signs, a rising prevalence of hypertension, as well as an overall alteration in adaptability to stressors of the aging body. We believe there is a need to reexamine our approach to vital signs with respect to ED triage and perhaps to secondary triage tools as well.
There are a few drawbacks to our study, including its small cohort, a single center study, the bias of patient selection. We chose a population that was admitted and thus selection bias towards a sicker population, and not a general ED population.
Shock index for decades has proven useful in detection of sepsis need for massive transfusion, yet it has not found its way yet into primary triage assessment algorithms. We believe our work exemplifies the need to reexamine the traditional vital signs within ED triage. There is a need for larger prospective studies that will examine SI and AASI as triage tools in the elder medical patient population.
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