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Three Part Question

In [patients attending the emergency department (ED)], could [point-of-care capillary lactate] be used to [measure illness severity]?

Clinical Scenario

70 year old male presenting to the emergency department with a 2 day history of fever and rigors with dysuria and increased urinary frequency. Could a point-of-care capillary lactate measurement be used to predict illness severity and prognosis?

Search Strategy

Medline (R) 1946-2016 June Week 4 using the OVID interface
Embase 1980-2016 Week 26
Global Health 1973-2016 Week 24
3 external sources

[(lactate.ti,ab.) OR (“point of care”. ti,ab.)] AND [(emergency medicine.ti,ab.) OR (trauma.ti,ab.) OR (emergency department.mp.) OR (Emergency Service, Hospital/)] LIMIT to human and yr= “1996-2016” and last 20 years

Search Outcome

94 abstracts and 13 full text articles were assessed for eligibility of which only 3 were relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Coats TJ et al 2002 England	23 adult patients attended by London Helicopter Emergency Medical Service and triaged to Royal London Hospital. “Difficult to triage” subgroup included 12 patients who had GCS >12 and BP >90mmHg. Fingerprick lactate was taken at incident scene. Device used: Accusport, Boehringer PLC (gives results in 60s. taken at incident scene)	Prospective cohort study	Correlation coefficient (R2 value) between early capillary lactate and Injury Severity Score (ISS)	Median ISS: 23 (range 1 to 50) R2 = 0.170	Small sample size. Lack elaboration on ethical oversight. Some data missing (i.e. patient characteristics, type of trauma and baseline values, cut-off point for elevated lactate, reason for exclusion of 1 patient). Use of fingerprick capillary lactate may not avoid the potential effects of peripheral vasoconstriction.
Contenti J et al 2014 France	103 patients from an emergency department in a French University Hospital. Capillary, venous and arterial lactate measured. Capillary earlobe sample taken within triage zone. 14 transferred to ITU. 63 had severe sepsis: 27 detected with clinical criteria and 36 classified after blood tests checked. 14 transferred to ITU, 12 discharged.Device used: Lactate Scout analyser (EKF Diagnostics, Wales UK) uses a 5microL blood sample, results in 10s	Prospective observational study	Effectiveness of capillary lactate to detect presence of severe sepsis	Areas under ROC curves = 0.747 +/- 0.047	Monocentric study. Study conducted in a centre with high incidence of severe sepsis which may not be able to generalize to the entire population.
			Association between blood lactate and mortality at 28 days	Overall mortality was near 20% (n=21). Capillary initial blood lactate was significantly different between patients who survived and those who died: 2.7+/- 2.5 vs 4.4 +/- 4.1
Manzon C et al 2015 France	176 patients presenting to the emergency department with clinical Systemic Inflammatory Response Syndrome (SIRS) defined by 2 criteria. Median age =72 years old. Fingerstick capillary lactate was measured by trained triage nurses for the study. Results were only available in 175 out of 176 patients. 150 patients hospitalized after ED admission (85%). Length of hospitalization average 7 days (2-13 days). Device used: Lactate Pro, Arkray Factory, Shiga, Japan	Prospective observational study	Mortality at 28 days	16% (29/176) Cut off = 3.6 mmol.L best predicts 28 day mortality	Monocentric study. Data missing from 1 patient without further explanation given. Device operation not explained. Use of fingerprick capillary lactate may not avoid the potential effects of peripheral vasoconstriction

Comment(s)

All studies assessed different outcomes of illness severity. Contenti evaluated the prognostic value of capillary lactate with severe sepsis and Manzon on SIRS whilst Coats studied its correlation with injury severity in a pre-hospital setting. Only Contenti collected arterial and venous samples simultaneously to analyze correlations with capillary lactate. The author concluded that the specificity of capillary lactate to detect a high venous lactate was low underestimating the severity of sepsis. Manzon further demonstrated that capillary lactate helped identify patients with altered microcirculation as 90% presented to ED without hypotension but with increased capillary lactate concentration. The point-of-care devices used in all 3 studies were different and operation use require further elaboration. Both Contenti and Manzon showed a positive association of elevated capillary lactate and high 28 day-mortality (20% and 16% respectively). Coats identified a moderate correlation (AUC=0.44) of raised capillary lactate and injury severity in the patient group who were difficult to triage.

Clinical Bottom Line

Elevated capillary lactate concentration is associated with high risk of death and injury severity. There is potential value of using capillary lactate as a cheap and time-saving point-of-care method in assessing prognosis. Further work recommended.

References

1. Coats TJ, Smith JE, Lockey D, et al. Early increases in blood lactate following injury. J R Army Med Corps 2002; 148:140-143
2. Contenti J, Corraze H, Lemoel F, et al. Effectiveness of arterial, venous and capillary blood lactate as a sepsis triage tool in ED patients American Journal of Emergency Medicine 2015; 33: 167-172
3. Manzon C, Barrot L, Besch G, et al Capillary lactate as a tool for the triage nurse among patients with SIRS at emergency department presentation: a preliminary report Annals of Intensive Care 2015; 5:7