Article, Pediatrics

Tachycardia may prognosticate life- or organ-threatening diseases in children with abdominal pain

a b s t r a c t

Background: Abdominal pain is common in children, but expeditious diagnosis of life- or organ-threatening dis- eases can be challenging. An evidence-based definition of tachycardia in children was established recently, but its diagnostic utility has not yet been studied.

Objective: To test the hypothesis that abdominal pain with tachycardia may pose a higher likelihood of life- or organ-threatening diseases in children.

Methods: A nested case-control study was conducted in a pediatric emergency department in 2013. Tachycardia was defined as a resting heart rate of more than 3 standard deviations above the average for that age. Life- or organ-threatening diseases were defined as “disorders that might result in permanent morbidity or mortality without appropriate intervention.” A triage team recorded vital signs before emergency physicians attended pa- tients. Patients with tachycardia (cases) and without tachycardia (controls) were systematically matched for age, sex, and month of visit. The groups were compared for the presence of life- or organ-threatening diseases.

Results: There were 1683 visits for abdominal pain, 1512 of which had vital signs measured at rest. Eighty-three patients experienced tachycardia, while 1429 did not. Fifty-eight cases and 58 controls were matched. Life- or organ-threatening diseases were more common in the case group (19%) than the control group (5%, p = 0.043). The relative risk of tachycardia to the presence of the diseases was 3.7 (95% confidence interval 1.2-12.0). Conclusion: Tachycardia significantly increased the likelihood of life- or organ-threatening diseases. Tachycardia in children with abdominal pain should alert emergency physicians to the possibility of serious illness.

(C) 2017

Introduction

Abdominal pain is one of the most common causes of unplanned medical visits. It comprises 5.1% of all chief complaints in the pediatric emergency department (ED). It is reported that as many as 92% of chil- dren with non-traumatic abdominal pain do not require any interven- tion and the patients recover completely by observation alone [1,2]. However, the remaining 8% need emergency medical or surgical inter- vention to save their lives. This includes a wide range of diseases, such as acute appendicitis, intussusception, mid-gut volvulus, diabetic ketoacidosis, Ovarian torsion, and so on. Thus, it is mandatory yet very challenging for emergency physicians to consider and rule out life- or organ-threatening illnesses in a precise and efficient manner.

* Corresponding author at: 133-0033, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan.

E-mail addresses: [email protected] (I. Hayakawa), [email protected] (H. Sakakibara), [email protected] (Y. Atsumi), [email protected] (H. Hataya), [email protected] (T. Terakawa).

Tachycardia suggests the possibility of an impending crisis of the cir- culatory system and is one of the most important physiological signs to watch for in the ED. Recently, an evidence-based definition of tachycar- dia in children was established [3-6]. However, the importance of tachy- cardia has never been evaluated in children with abdominal pain.

This nested case-control study demonstrated that tachycardia at tri- age may prognosticate life- or organ-threatening conditions in children with abdominal pain in the ED. This study provides unique evidence of the importance of tachycardia in patients with abdominal pain.

Methods

Definition of terms

Tachycardia was defined as an elevated heart rate at rest that corre- sponds to the triage level 1 heart rate range in the Canadian Emergency Department Triage and Acuity Scale (CTAS), which are heart rates pre- senting more than 3 standard deviations above or below the average for that age [3-5]. Life- or organ-threatening diseases were defined as

http://dx.doi.org/10.1016/j.ajem.2017.01.032

0735-6757/(C) 2017

Power calculations,”>820 I. Hayakawa et al. / American Journal of Emergency Medicine 35 (2017) 819822

“disorders that without appropriate medical or surgical intervention might result in permanent morbidity or mortality,” including, for example, acute appendicitis, acute cholangitis, sepsis, acute myocarditis, intussusception, Bowel obstruction, pancreatitis, urinary tract infection, diabetic ketoacidosis, and testicular or ovarian torsion. Non-life- or organ-threatening diseases were defined as “illnesses from which patients recover completely without medical support and from which lifelong complications do not result,” such as acute gastroenteritis and non-specific abdominal pain [7].

Study design and setting

This is a nested case-control study in a cohort of children at a single pediatric ED in a large academic children’s hospital from January to December 2013. The hospital serves a community of 4 million people, and the ED unit admits about 38,000 children annually.

Triage

All ED visits were first triaged by a triage team. The team consists of nurse practitioners that are thoroughly educated on pediatric emergen- cy triage skills through hands-on and theoretical trainings. All triage data were prospectively collected by an in-hospital electronic triage sys- tem (eTriage(R), DankNet and DoWell Inc., Tokyo, Japan) and served as the mother cohort. The triage system was developed in accordance with previous literature [8,9]. Of note, the system requires the triage team to choose the patients’ chief complaint from a large variety of pos- sible complaints that are pre-designated in the system. For example, if the patient and their caregivers first complain of “abdominal pain, vomiting, mild fever, and loose stools,” the triage team should select, through the triage, the most significant health concern of the patient, such as “abdominal pain.” This provides simple and efficient communi- cation between the triage team and the emergency physicians, avoiding lengthy and poorly specified lists of complaints. Thus, for each visit in

the ED, the chief complaint and the full vital signs (level of conscious- ness, respiratory rate, heart rate, blood pressure, and body temperature) were always documented before the emergency physicians attended the patients. The data were then automatically exported to the hospital’s electronic health records system after triage.

Study population

Eligibility criteria for case visits were as follows: 1) the chief complaint of abdominal pain, 2) an age of less than 18 years, and 3) vital signs measured at rest showed tachycardia. For each case, a matched control visit was selected. Eligibility criteria for control visits were as follows: 1) the chief complaint of abdominal pain, 2) the same sex to the matched case, 3) control visit made in the same month as the matched case, 4) an age of less than 18 years with an age discrepancy of 1.5 years or less between the case and control for each case-control pair, and 5) vital signs measured at rest did not show tachycardia. Importantly, researchers had access to the triage data but not to the hospital’s electronic health records during selection of the cases and matched controls. Thus, they were blinded to the emer- gency physicians’ diagnoses during the study population selection. This prevented potential bias that may have been caused by the researcher inadvertently excluding life- or organ-threatening diseases from the control data and vice versa. After the selection of the two groups, the researchers were allowed to access the electronic health records of the patients, and final diagnoses were determined.

Sample size and power calculations, data collection, and analyses

The overall incidence of life- or organ-threatening diseases in chil- dren with abdominal pain in ED was estimated to be 7% [1]. Assuming the incidence would reach 3-fold (21%) in the case group and would be half (3.5%) in the control group, the required sample size was

N = 37,961

Visits in the year 2013

N = 1683

Visits with abdominal pain

age < 18 years

N = 1512

Heart rate at triage measured at rest

N = 171

Heart rate at triage measured while crying

N = 83

Tachycardia (+)

N = 1429

Tachycardia (-)

N = 58

Case group

N = 58

Control group

Matching for age, sex, and month of the visit

Fig. 1. Study design and flow of patients’ selection.

I. Hayakawa et al. / American Journal of Emergency Medicine 35 (2017) 819822 821

determined to be 59 in each group when alpha and beta error rates were

0.05 and 0.2, respectively. Age, sex, heart rate, respiratory rate, and final diagnosis were collect-

ed. Final diagnoses were categorized as either life- or organ-threatening

Table 2

List of life- or organ-threatening diseases in case and control groups. Heart and respiratory rates at triage and final diagnoses of life- or organ-threatening diseases are shown.

Case group

disease or not. As was mentioned in Section 2.4 Study population, the two groups were matched for age (b 1.5 years discrepancy), sex, and months

Age (year)

Sex Heart rate

Respiratory rate

Final diagnosis

of the visits. Fisher’s exact probability test was used to test for differ- ences in the incidence of life- or organ-threatening diseases between the two groups.

1 Male 173 28 Intussusception

7 Female 143 28 Acute appendicitis

7 Female 164 32 Urinary retention, acute renal failure

Female 140 32 Acute appendicitis

3. Results

9

10

Female

Male

136

126

32

20

Acute appendicitis

Acute appendicitis

10

Female

129

22

Acute appendicitis

3.1. Baseline characteristics

11

Male

129

38

Acute appendicitis

13

Male

120

18

Acute appendicitis

Of 37,961 ED visits in 2013, 1683 (4.4%) were for abdominal pain. Of these, vital signs were measured at rest in 1512 (89.8%) visits. Eighty- three patients experienced tachycardia while 1429 did not. Fifty-eight patients and 58 controls were recruited (Fig. 1). In each group, the me- dian age was 6.5 years (with an interquartile range of 4-10 years).

Control group Age

14

Male

122

26

Acute appendicitis, bowel obstruction

17

Female

120

24

Urinary tract infection

(year)

Sex Heart

rate

Respiratory rate

Final diagnosis

Males comprised 48% of the population (28 of 58 visits).

3.2. Main results

The overall incidence of life- or organ-threatening disease was 12% (14 of 116). The frequency of life- or organ-threatening diseases was significantly higher in the case group (11 of 58, 19%) than in the control group (3 of 58, 5%, p = 0.043, Fisher’s exact probability test) (Table 1). The relative risk, positive likelihood ratio, and negative likelihood ratio of tachycardia to the presence of a life- or organ-threatening disease was 3.7 (95% confidence interval 1.2-12.0), 1.7 (1.1-2.1) and 0.4 (0.1- 0.9), respectively. The specific details of life- or organ-threatening dis- eases are listed in Table 2. Acute appendicitis was the most frequent cause, followed by 3 cases of urinary tract infection and 2 cases of intus- susception. No patients died or suffered permanent morbidity.

Discussion

Tachycardia correlated with life- or organ-threatening diseases in children with abdominal pain. The case group showed 3.7-fold increase in the incidence of life- or organ-threatening disease compared to the control group.

Definition and recognition of tachycardia in children

Tachycardia is the most important vital signs to watch for in the ED because it suggests the possibility of an impending crisis of the circula- tory system, i.e. compensatory shock. However, pediatric tachycardia has proved to be very difficult to study scientifically because evidence- based age-adjusted normal heart rate ranges were lacking.

Until recently, pediatric tachycardia was often evaluated with the use of heart rate ranges in the pediatric advanced life support American Heart Association guidelines [10] or using other guidelines. Pediatric

Table 1

Tachycardia increases the likelihood of patients suffering from life or organ threatening diseases (p = 0.043, Fisher’s exact probability test). Numbers in parentheses denote 95% confidence intervals.

Life or organ threatening diseases

Yes

No

Tachycardia Yes

11

47

58

No

3

55

58

14

102

116

Relative risk = 3.7 (1.2-12.0).

Positive likelihood ratio = 1.7 (1.1-2.1).

Negative likelihood ratio = 0.4 (0.1-0.9).

3 Male 108 24 Intussusception

5 Female 134 24 Urinary tract infection

Female 82 20 Acute appendicitis

Advanced Life Support guidelines, for example, divide the ages from birth to 18 years of age into as little as 4 categories in order to describe the normal heart rate ranges of each category. This simple a priori cate- gorization might not represent the true heart rate distribution through- out childhood.

Recent advances in this field changed the situation. A systematic review in 2011 [6] on normal ranges of Heart and respiratory rates in children systematically gathered current observational data on pediatric vital signs, and revealed a wide discrepancy between the actual distri- bution curves and the heart rate ranges in previous guidelines and stud- ies. The CTAS National Working Group adopted this newly developed evidence on heart rates and revised the CTAS accordingly [3-5]. This re- vision has enabled pediatric health care providers to carry out studies on pediatric tachycardia with increased certainty.

Our ED adopted the new heart rate range definition in 2013. Accord- ing to the CTAS, triage level 1 abnormality corresponds to 3 standard deviations above or below the normal heart rate distribution curves. In our ED, in order to recognize Abnormal vital signs quickly and effi- ciently, the vital signs are automatically color-coded in the electronic health records once the vital signs are recorded in the electronic triage system, and are then exported to the electronic health record system (level 1 in blue, level 2 in red, level 3 in yellow, and level 4 or 5 in green). The color-coding allows the emergency physician to promptly recognize any abnormal vital signs in a patient.

Importance of tachycardia in children with abdominal pain

To our knowledge, this is a unique study that suggests the diagnostic importance of tachycardia with acute abdomen. Historically, it was sug- gested that tachycardia might not become apparent unless the patient was collapsing due to overt peritonitis [11]. Tachycardia in cases of ab- dominal pain has been given little attention if patients do not appear to be sick. We demonstrated that tachycardia has a 3.7-fold increased relative risk of life- or organ-threatening diseases. In addition, no patients died or suffered permanent complications in our cohort. The results suggest that tachycardia may be an early sign of acute abdomen, not merely a late consequence of it. We suggest that emergency physi- cians utilize heart rate information as one of the key decision making tools in the ED, in conjunction with thorough consideration of the patient’s history and a physical examination, in looking for signs the patient may experience a life- or organ-threatening disease.

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Strengths and limitations

The strengths of our study were as follows. 1) The vital signs were measured by a triage team member who received a set of training courses on pediatric triaging. The team is highly capable in measuring reliable and reproducible vital signs in children. This is illustrated by the fact that as much as 89.8% of patients had their vital signs collected while at rest, as opposed to crying, as may be common in children visit- ing the ED. 2) Potential biases in data acquisition and data collection were carefully controlled. First, all the vital signs were measured and re- corded to our triage database before emergency physicians attended the patients. This precludes the possibility that the triage team could inad- vertently skew the vital signs of children in one direction or the other, since the triage team never knew the final diagnosis at the time of tri- age. Second, the researcher was blinded to patients’ charts during the selection of the two groups to prevent a potential bias due to the re- searcher inadvertently including life- or organ-threatening diseases to the case group and/or excluding them from the control group.

There are 3 limitations. 1) The relatively small sample size does not permit any definitive statement on this issue. Further validations in other cohorts are warranted. 2) Due to the rarity of the illness, several important life- or organ-threatening diseases, such as myocarditis and diabetic ketoacidosis, were not encountered in our study. It is not known whether these life- or organ-threatening diseases may also tend to present with tachycardia or not. Further research using case- control studies with instances of these rare but life-threatening diseases will be needed to clarify this issue. 3) The mechanisms of tachycardia in life- or organ-threatening diseases are not clear. We studied only the correlation of tachycardia to life- or organ-threatening diseases. Further investigation will be necessary to give insights into the pathophysiolog- ical mechanism of life- or organ-threatening diseases that causes tachy- cardia (such as dehydration and systemic inflammatory response syndrome) [12,13].

Conclusion

Life- or organ-threatening diseases were significantly more common if the patient showed tachycardia at triage (19% vs. 5%). Tachycardia in children with abdominal pain should alert emergency physicians to the possibility of serious illnesses.

Authors’ contribution

I.H. and Y.A. designed the study. I.H. collected and analyzed the data.

I.H. and H.S. interpreted the data. I.H. drafted the article. H.S., Y.A., H.H., and T.T. critically revised the article. All the authors gave final approval of the version to be published.

Compliance with ethical standards

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/ or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study was approved by institutional review board of Tokyo Metropolitan Children’s Medical Center (Trial number H27b-31) and is registered in

University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR Trial number UMIN000019258).

Conflicts of interest

Itaru Hayakawa, Hiroshi Sakakibara, Yukari Atsumi, Hiroshi Hataya and Toshiro Terakawa declare that they have no conflicts of interest.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Financial support

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Acknowledgements

We are grateful to Dr. Nobuaki Inoue, the triage team staffs, and all our colleagues at the Division of Pediatric Emergency Medicine, Depart- ment of Pediatric Emergency and Critical Care Medicine in Tokyo Metro- politan Children’s Medical Center, for useful discussions and taking care of the patients.

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