OUTCOME OF PATIENTS ADMITTED WITH EXERTIONAL HEAT RELATED ILLNESS IN INTENSIVE CARE UNIT OF TERTIARY CARE HOSPITAL

An observa onal cross-sec onal descrip ve study was done among those recruits admi ed in Intensive Care Unit of military ter ary care hospital with diagnosis of heat related illness from June 2016 to August 2017 A.D. Data based on hospital case records were collected and analyzed using SPSS version 22. Primary outcome studied was mortality. Secondary outcomes studied were length of stay in ICU, hospital and on ven lator.


Objec ve
The study was undertaken to iden fy its outcome in recruits admi ed in intensive care units of military ter ary care hospital.

Methods
An observa onal cross-sec onal descrip ve study was done among those recruits admi ed in Intensive Care Unit of military ter ary care hospital with diagnosis of heat related illness from June 2016 to August 2017 A.D. Data based on hospital case records were collected and analyzed using SPSS version 22.Primary outcome studied was mortality.Secondary outcomes studied were length of stay in ICU, hospital and on ven lator.

Results
Out of 17 recruits, 12 were diagnosed as heat exhaus on and 5 were diagnosed as heat stroke.SOFA score for heat stroke and heat exhaus on pa ents ranged from 2-16 and 0-2 with respec ve mortality rate 7-95% and 0-7%.APACHE II score for heat stroke and heat exhaus on pa ents ranged from 5-33 and 0-5 with respec ve mortality rate 5.80-73% and 0-5.80%.There was no mortality among 12 heat exhaus on pa ents.Out of 5 heat stroke pa ents, 3 died with 60% mortality rate.Heat stroke pa ents had maximum stay of 4 days in ICU, hospital for 5 days and ven lator for 4 days.

Conclusions
Exer onal heat related illness is common in young military trainee with heat exhaus on and heat stroke being common causes for ICU admission.Heat stroke has higher mortality rate due to mul ple organ dysfunc on.

INTRODUCTION
Heat related illness (HRI) due to high ambient temperature and humidity are very common in tropical region of Nepal 1 during summer.Exer onal heat related illness par cularly heat stroke is a life threatening condi on that frequently 2,3,4 occur in young military trainee.Heat related illness occurs when there is failure of thermoregulatory response to maintain core body 5 temperature between 36° -38° C. Types of HRI are heat cramps (muscle cramping), heat syncope (fain ng), heat exhaus on (hypotension followed by collapse) and heat stroke which is the severe form where core body temperature 6 is >40°C leading to central nervous system dysfunc on.Mortality rate of heat stroke varies from 10 -70 % with 6 persistent neurological damage in 7-20% of survivors.Heat stroke can be non-exer onal or exer onal resul ng from 5,6 excessive heat produc on during strenuous ac vity.Every year many recruits suffer from HRI at Nepali Army training centre.The objec ve of the study was to iden fy clinical outcomes of exer onal heat related illness in those recruits who were admi ed in ICU of military ter ary care hospital.

METHODS
A er an ethical approval of Ins tu onal Research Commi ee (IRC), an observa onal cross-sec onal descrip ve study was conducted among those recruits involved in military training at recruit training centre of Nawalparasi who were admi ed in Intensive Care Unit (ICU) of military ter ary care hospital with the diagnosis of exer onal heat related illness (HRI) from June 2016 to August 2017 A.D. Inclusion criteria were all male military recruits involved in long distance running during their training in monsoon season from June to August, referred to ICU of military ter ary care hospital with signs & symptoms of exer onal HRI like heat cramps, heat syncope, heat exhaus on and heat stroke.All other military recruits with diagnosis of non exer onal heat related illness were excluded.A er stra fied random sampling, data were collected based on hospital case records.Out of 83 soldiers who have HRI in 2 years, 17 were referred and admi ed to ICU of military ter ary care hospital.Diagnosis was made based on clinical presenta ons.Baseline clinical and inves ga on data were obtained from individual case records included in the study.Clinical variables (Table 3) such as body temperature, heart rate, respiratory rate, mean arterial pressure and Glasgow Coma Scale (GCS) were noted.Major outcome variables (Table 4) such as complete blood count, coagula on profile, arterial blood gas analysis, liver func on tests, renal func on tests and hemodynamic stability were obtained.Predictor variables (Table 3 and Table 4) obtained were temperature, respiratory rate, heart rate, mean arterial pressure, use of ionotropes/vasopressors (Noradrenaline/Dopamine), total leukocyte count, hematocrit, platelet count, serum crea nine, serum sodium, serum potassium, bilirubin, arterial pH, PO2/FiO2 ra o, arterial bicarbonate, GCS and urinary output.Based on predictor variables, severity of illness for outcome predic on was assessed within 24 hr of diagnosis of heat related illness using Acute Physiology and Chronic Health Evalua on (APACHE) II and Sequen al Organ Failure assessment (SOFA) scoring system.All the data were entered and analysis was done using Sta s cal Package for Social Sciences (SPSS) version 22.Primary outcome studied was mortality or discharged a er improvement.Secondary outcomes studied were length of ICU stay, length of hospital stay and number of days on ven lator.

RESULTS
Out of the 17 recruits, 12 (70.58%)was diagnosed as heat exhaus on with 8 (66.66%) in 2016 A.D. and 4 (33.33%) in 2017 A.D. whereas remaining 5 recruits (29.41%) was diagnosed as heat stroke with 3 (60%) in 2016 A.D. and 2 (40%) in 2017 A.D. (Table 1) Out of the 12 heat exhausted pa ents, no one had mortality thereby all improved and discharged.Out of 5 heat stroke pa ents, three died with 60% mortality rate.(Table 2)  Severity of was studied by using SOFA and APACHE II scoring system (Table 5 and Table 6).Out of 12 Heat exhaus on pa ents (Table 5), six has zero SOFA and APACHE II scores.The mean SOFA scores (Table 7) for heat stroke pa ents were 9.40 ± 6.10 with predicted mortality rate of 50%.The mean SOFA score for heat exhaus on pa ents was 1 ± 1.04 with predicted mortality rate of 3.50%.The mean APACHE II scores (Table 7) for heat stroke pa ents were 18.60 ± 12.81 with predicted mortality rate of 37.88%.The mean APACHE II score for heat exhaus on pa ents was 2.50 ± 2.61 with predicted mortality rate of 2.90%.The common organ systems involved were neurological (64.70%), cardiorespiratory (29.41% pa ents) and renal (29.41%) with 100% involvement of these organ systems in heat stroke.

Score ± SD
1 ± 1.04 Among those one died in 2016 (33.33%)where as two (66.66%)died in 2017.The secondary outcome of heat related illness (Table 8) was studied in terms of mean ICU stay, mean Hospital stay and mean Ven lator stay.The mean ICU stay among HRI pa ents was 2.44 ± 0.85 SD with maximum stay of four days in one (5.60%)heat stroke pa ent and minimum stay of one day (16.7 %).The mean hospital stay among HRI pa ents was 3.28 ± 1.07 SD with maximum stay of five days in one heat stroke pa ent (5.60%) and minimum stay of two days (11.10 %).The mean stay on ven lator among HRI pa ents all being those of heat stroke was 0.39 ± 0.97 day with maximum stay for four days in one heat stroke pa ent (5.60%) and minimum stay for one day in three heat stroke pa ents (16.70%).with significant morbidity and mortality.There has been 7 studies in marine corps recruits in United Kingdom and 8 military recruits in United States Army dealing with risk factors of heat related illness but none has described about its outcome.
In our study, we found that out of the 17 recruits, 12 (70.58%)was diagnosed as heat exhaus on whereas remaining 5 recruits (29.41%) was diagnosed as heat stroke.We used SOFA score and APACHE II scoring system to assess the severity of HRI admi ed in ICU.They are common scoring systems used in cri cally ill pa ents to assess disease severity and predict their outcome in terms of mortality.We found that both the SOFA and APACHE II scores showed high mean score for pa ents with heat stroke (9.40 ± 6.10 and 18.60 ± 12.81) pa ents than for heat exhaus on (1±1.04 and 2.50 ± 2.61).The predicted mortality rate as shown by both scores for heat stroke was 50% and 37.88% where as that for heat exhaus on was 3.50% and 2.90%.The actual mortality rate observed in our study was 60% for heat stroke pa ents (three out of five) and none for heat exhaus on thereby showing that severity of illness related to mortality.was similar to 2 the retrospec ve study done by Kalaiselvan MS et al in India where mortality rate was 34% in nine heat stroke pa ents among 26 heat related illness pa ents.
The secondary outcome of our study as observed in terms of mean ICU stay, mean hospital stay and mean stay on ven lator days showed that stroke pa ents had maximum stay as compared to heat exhaus on thereby related to mortality.Neurological (67.40%), cardiorespiratory (29.41%) and coagula on dysfunc on (29.41%) were seen as the main causes of mortality which were similar to that done by Kalaiselvan et al where there was 100 % involvement of neurological system.

CONCLUSION
Exer onal heat related illness is common in young military trainee with heat exhaus on and heat stroke being common for ICU admission.Heat stroke has higher mortality rate due to mul ple organ dysfunc on.

RECOMMENDATIONS
We recommend larger case control or cohort study involving mul ple training centers throughout the country that can tell us the associa on of various risk factors with outcome.

LIMITATIONS
The limita on of our study was smaller size of study popula on thereby not represen ng recruits from other military training centre of Nepali Army.Mul hospital based study must done to find outcome of heat related illness not only in recruits from Nepali Army but also from Armed Police Force and Nepali Police.Similarly, our study does not tells us about the associa on of outcome with risk factors.

Table 1 :
Frequency distribu on of HRI admi ed in ICU in 2016-2017 A.D.

Table 5 :
Mortality predic on of HE by severity of illness using SOFA and APACHE II Scores

Table 6 :
Mortality predic on of HS by severity of illness using SOFA and APACHE II Scores

Table 8 :
Secondary outcome of Heat related illness