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Three Part Question

In [a patient presenting to the emergency department with non-thermal trauma] is [serum lactate] a [predictor of mortality]?

Clinical Scenario

A 40 year-old man presents to the emergency department with multiple injuries after being involved in a road traffic crash. You wonder whether an initial serum lactate taken in the ED is a useful predictor of mortality.

Search Strategy

Medline 1950-1/2008 using the OVID interface
[(lactic acid.mp OR exp lactic acid/ OR lactate.mp OR lactic acidosis.mp OR exp Acidosis, Lactic/) AND (trauma.mp OR exp ¡§Wounds and Injuries¡¨/) AND (emergency department.mp OR exp Emergency Service, Hospital/ OR admission.mp OR exp Patient Admission/)] LIMIT to human AND English

Search Outcome

One hundred and eighteen papers found of which six were relevant (see table).

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Manikis et al, 1995, Belgium	129 trauma patients admitted to Intensive Care of a university-based hospital from 1992 to 1993. Overall mortality 22%. Arterial lactate measured.	Prospective cohort study	Mortality	Mean lactate: Survivors=2.8 (CI 0.4-10.2); Non-survivors=4.0 (CI 1-12.7); (p<0.05)	Study conducted in intensive care unit; early deaths within 24 hours were excluded; gunshot and stab wound injuries were not separated.
Lavery et al, 2000, USA	375 patients admitted to an urban trauma centre. Overall mortality 10%. Arterial and venous lactate measured.	Prospective cohort study	Correlation	Mean arterial lactate=3.11 (CI 2.67-3.55); Mean venous lactate=3.43 (CI 2.96-3.9); Correlation=0.94 (p=0.001)	Only 221 out of 375 patients had both arterial and venous lactate taken; patients with penetrating and blunt injuries were not separated.
			Mortality	Arterial lactate OR=1.1 (CI=0.98-1.15); Venous lactate OR=1.2 (CI=1.15-1.35)
			Mortality	Venous lactate: SN=95%; SP=43%; PPV=16%; NPV=99%
Cerovic et al, 2003, Slovenia	98 severely injured patients (ISS>16) admitted to Surgical Intensive Care Unit directly from the Surgical Emergency Unit. Overall mortality 25.5% (73 survivors and 25 non-survivors) Arterial lactate measured.	Prospective cohort study	Mortality	Lactate after 12 hours predicted survival (p=0.009); Lactate on admission did not prove to be a predictor of mortality.	Study conducted in intensive care unit; only severely injured patients were included; patients who died during the first 12 hours after admission were excluded; sample size small.
Aslar et al, 2003, Turkey	64 patients with torso trauma admitted to emergency department from 1996 to 1998. Overall mortality was 39.1% (39 survivors and 25 non-survivors) Arterial lactate measured.	Prospective cohort study	30 day mortality	Univariate analysis of lactate > = 4: Chi square=29.34 (p<0.001); Logistic regression of lactate: OR=10.58 (p=0.0073)	Sample size small; patients with major head injury were excluded; patients included had a very high mortality; patients admitted for observation only were excluded.
Pal et al, 2006, USA	5995 patients admitted to the trauma registry of a university-based trauma centre from 1997 to 2003. Overall mortality was 3%.	Prospective cohort study	Mean lactate value	Survivors=3.0 +/- 0.04; Non-survivors=5.2 +/- 0.3 (p < 0.0001)	Patients with penetrating and blunt injuries were not separated.
			Elevated lactate > 2.0	SN=85%; SP=38%; PPV=4%; Area under ROC curve=0.72
			Subgroup: died within 48 hours	PPV=11%
			Subgroup: ISS>20	Area under ROC curve=0.69
			Subgroup: age>50	Area under ROC curve=0.65
Kaplan and Kellum, 2004, USA	282 Trauma patients requiring vascular repair from 1988 to 1997. Overall mortality was 22.7%. (218 survivors and 64 non-survivors)	Retrospective study	Mean lactate value	Survivors 3.6 (SD 1.5); nonsurvivors 11.1 (SD 3.6) (p,0.001)	Retrospective study; study focused on a specific group of patients requiring vascular repair lacking generalisablility; patients who died in the ED were excluded; penetrating and blunt injuries not separated.
			28-day mortality	Area under ROC curve 0.981 (CI 0.957–0.993)

Comment(s)

Although three of the five studies concluded that serum lactate taken either in the ED or on admission is useful in predicting mortality, and most of the studies were able to show a statistically significant difference in the initial lactate level between survivors and non-survivors, elevated initial lactate levels had a low positive predictive value for death. The study by Aslar et al did show a large odds radio, but the study suffered from a small sample size with a very high mortality. Pal et al published a very large retrospective study but did not report negative predictive values. However, the sensitivity of an initial elevated lactate for death reached 85-95% in several studies, indicating the potential role of using initial lactate levels to identify patients at low risk of death following non-thermal blunt trauma. Larger studies are required to answer this question adequately.

Clinical Bottom Line

The initial lactate level does not identify patients at high risk of death, but it may have a role in identifying patients at low risk of death following blunt trauma.

References

1. Manikis P, Jankowski S, Zhang H, Kahn RJ, Vincent JL. Correlation of serial blood lactate levels to organ failure and mortality after trauma. American Journal of Emergency Medicine 1995; 13:619-22
2. Lavery RF, Livingston DH, Tortella BJ, Sambol JT, Slomovitz BM, Siegel JH. The utility of venous lactate to triage injured patients in the trauma center. Journal of the American College of Surgeons 2000;190:656-64.
3. Cerovic O, Golubovic V, Spec-Marn A, Kremzar B, Vidmar G. Relationship between injury severity and lactate levels in severely injured patients. Intensive Care Medicine 2003;29:1300-5.
4. Aslar AK, Kuzu MA, Elhan AH, Tanik A, Hengirmen S. Admission lactate level and the APACHE II score are the most useful predictors of prognosis following torso trauma. Injury 2004;35:746-52.
5. Pal JD, Victorino GP, Twomey P, Liu TH, Bullard MK, Harken AH. Admission serum lactate levels do not predict mortality in the acutely injured patient. Journal of Trauma-Injury Infection & Critical Care 2006;60:583-7.
6. Kaplan LJ, Kellum JA. Initial pH, base deficit, lactate, anion gap, strong ion difference, and strong ion gap predict outcome from major vascular injury. Crit Care Med 2004;32:1120–4.