1. Glucose in Trauma Tarik Sammour, Arman Kahokehr
Stuart Caldwell, Andrew G Hill
MIDDLEMORE HOSPITAL
Auckland, NZ

2. Middlemore Trauma Registry
Started May 2000
Prospectively collected
All admissions > 24h
Maintained by nurse specialist and fellow
Currently 20,500 entries
Records ISS and TRISS scores
Firstly some background on Middlemore. It covers a population of 460,000 ppl in S Auckland.
Approx 2500 trauma admissions per year (includes minor injuries admitted >24h).
Trauma registry started in May 2000 as a prospectively collected database of trauma outcomes.
Based on Collector for Windows Data Management System version 3.37, Digital Innovation Inc, Maryland, USA
20500 entries as of April 2008.
Collector records ISS (Injury Severity Score) and TRISS (Trauma and Injury Severity Score).

3. Utility of Trauma Scores
Predict mortality
Patient disposition (need for ICU?)
Counselling patient and family
However…
Complex to calculate in acute situtation
Mainly used in audit and research
Many trauma scores have been developed. Main drawback to all of them is difficult to calculate in the hustle and bustle of ED due to complexity and missing values.

4. Calculating trauma scores
6 body regions
Score each from 1 - 6
ISS
(Region A)² + (Region B)² + (Region C)²
TRISS
ISS + (physiological parameters) + age
ISS developed in the 70’s by Baker is the most widely used score, and the main one used in our registry.
Derived from Abbreviated Injury Severity (AIS) coding, AIS divides the body into 6 regions, Sum of the squares of the AIS severity measure in the three most injured body regions
Good score but has some limitations…
TRISS current international standard
Includes GCS, systolic BP, respiratory rate, and age.

5. Limitations of current scores
ISS
Statistical:
Ordinal rather than continuous score
Score is not monotonous
e.g. Kilgo et al. mortality of 43% with ISS 25, and only 14% with an ISS of 27 (a worse score)
Clinical: No measure of physiological compromise
TRISS (ISS plus physiological parameters)
Requires atleast 8, and as many as 10 variables
=> missing values common
ISS is scaled from 1 to 75 but actually only takes 44 distinct values which are not uniformly distributed. Because of this, ISS cannot be treated as a continuous measure but rather as an ordinal scale.
Kilgo et al (J Trauma. 2006;60:1002–1009) demonstrated in analysis of over 350,000 trauma patients that ISS scores do not represent monotonically increasing functions of mortality.
TRISS
More variables = more missing data.

6. Glucose metabolism in Trauma
Blood glucose level increases
Overproduction of endogenous glucose
Relatively low insulin production
Lactate level increases
Shift to anaerobic metabolism
Reduction in lactic acid elimination
Aerobic glycolysis in skeletal muscle secondary to epinephrine stimulated ATPase activity
So we hypothesised that and increase in glucose and lactate levels may be an early predictor of mortality.

7. Question Can we utilise glucose and lactate levels
to predict mortality in trauma patients?

8. Method Trauma registry search Time period: May 2000 – Sept 2006
Inclusion: All adult patients requiring a trauma team call out
Exclusions: Diabetics and Burns
Data collected
Demographics
Background medical history
Admission glucose and lactate
ISS and TRISS scores
Mortality

9. Patients included Male 892 (74.5%) Female 305 (25.5%)
Mechanism of Injury Number
Road traffic accident 746
Assault 152
Fall
Animal Related 7
Work related 38
Sport 18
Self inflicted 60
Unknown 74
Male 892 (74.5%)
Female 305 (25.5%)
Mortality rate 3.7%

10. Mechanism Mechanism of Injury Number Road Traffic Accident 746 Assault
152
Fall
102
Self Inflicted 60
Work related 38
Sport 18
Animal related 7
Unknown 74

11. Data ranges Missing Values Median (Range) Age ISS TRISS Gluc Lact
(15 – 90)
ISS
(1 – 75) 7
TRISS
(0.001 – 0.997)
201
Gluc
(3.1 – 31.4)
120
Lact
(0.5 – 18)
847
Out of 1200 patients
There were 200 TRISS values (1/6th) that couldn’t be calculated because of missing data
Also, 70% of patients didn’t have a lactate level presumably as it was not clinically indicated.

12. Results - Glucose Glucose > 11.0 mmol/L defined as elevated
Gluc > 11.0 mmol/L => mortality rate 13.4%
Gluc < 11.0 mmol/L => mortality rate 1.8%
(p < ).
Specificity 93.2% for death.
Sensitivity 37.9% for death.
Positive predictive value (PPV) was low (13.4%)
Negative predictive value (NPV) was high (98.2%)
996 gluc < 11
82 gluc > 11
Approx 100 patients had gluc > 11

13. Results - Lactate Lactate > 2.0 mmol/L defined as elevated
Lact > 2.0 mmol/L => mortality rate 13.0%
Lact < 2.0 mmol/L => mortality rate 2.7%
(p = ).
Specificity 56.8% for death.
Sensitivity 81.0% for death.
Positive predictive value (PPV) was low (13.0%)
Negative predictive value (NPV) was high (97.4%)
189 Lact < 2
160 Lact > 2
Sens higher and spec lower because sick patients were pre-selected.

14. Combining gluc and lact
Neither
elevated
Gluc or Lact
Both
Mortality
2.9%
7.6%
25.5%
Specificity of 60.7%
Sensitivity of 70.0%

15. Some aberrant results at v high glucose => combined into one group > 17.

16. Generally accepted threshold for a good predictive test is 0.8.
Glucose level meets the threshold, with a predictive value similar to that of the ISS score.
TRISS score is an exceptional predictor deserving of it status as international standard and lactate is somewhat less predictive (although this only included one third of the patients).
Gluc std error => (0.787 – 0.903). Maximal sens and spec at Gluc 8.5 => sens 75.9%, spec 75.8%. Gluc < 8.5 => 1.5% of 802 died, Gluc >= 8.5 => 8.0% of 276 died.
ISS std error => (0.796 – 0.912)
TRISS std error => (0.938 – 0.987)
lact std error => (0.598 – 0.834). Maximal sens and spec at Lact 2.4 => sens 65.4%, spec 63.9%

17. Conclusions
Glucose and lactate can predict mortality in severely injured patients.
Venous glucose is a good predictive test and equivalent to the ISS score.
It is easier to obtain and more practical to use in the emergency setting.
Limitations:
Retro review
Trauma registry data input is inaccurate
Lots of missing lactate data
Previous analysis of 450 patients that died or went to ICU – no trauma call in 17%