Moore CC, Jacob ST, Pinkerton R, Meya DB, Mayanja-Kizza, Reynolds SJ, et al. Point-of-care lactate testing predicts mortality of severe sepsis in a predominantly HIV type 1-infected patient population in Uganda. Clin Infect Dis 2008 Jan 15;46(2):215-22.
To evaluate the ability of a handheld portable whole-blood lactate (PWBL) analyzer to predict mortality in patients who are admitted to the hospital with severe sepsis.
A prospective observational study.
An accident and emergency department of Mulago Hospital, a national referral hospital in Kampala, Uganda.
72 patients were enrolled in the study. Inclusion criteria were ≥18 years of age and admission to a medical ward, along with: 1. two or more systemic inflammatory response syndrome criteria (body temperature, >38°C or <36°C; heart rate, >90 beats/min; respiratory rate, >20 breaths/min; or peripheral WBC concentration, >12,000 cells/mm3 or <4000 cells/mm3; or thermodysregulation; 2. systolic blood pressure ≤100 mm Hg; and 3. a suspected infection. Exclusion criteria included acute cerebrovascular events, gastrointestinal hemorrhage, or admission to the surgical or obstetrics and gynecology ward.
There was no intervention in this study. This analysis was conducted among a subset of 253 patients recruited to study the incidence, management, and outcomes of sepsis. From this sample, the first and last 50 consecutively enrolled patients were recruited to determine the predictive value of PWBL in predicting mortality from sepsis. Background information - including age, sex, HIV-1 serostatus, and prescribed antiretroviral medicines (ARVs)-was recorded. At patient enrollment, temperature, heart rate, respiratory rate, and blood pressure were measured. To determine outpatient survival, an attempt was made to telephone patients 30 days after their discharge from the hospital. A rapid HIV-1 test and malaria smear were performed at Mulago Hospital. A local private clinical laboratory provided results of lactate and bicarbonate analysis. PWBL was obtained using a lancet to collect a drop of whole blood from the patient's finger, for analysis by a handheld portable device. This instrument uses enzymatic determination and reflectance photometry of lactate in the plasma portion of whole blood using a measurement strip. Standard laboratory serum lactate (SLSL) concentration was obtained by phlebotomy for venous blood samples. Within 2 hours of sample collection, the sample was transported in a standard serum tube via a cooler to the clinical laboratory, where blood was centrifuged and serum was removed for use in the lactate assay.
Information was available for 72 of the 100 enrolled subjects. The mean age of participants was 35.7, 61.1% were women, and 81.9% were HIV infected, with a mean CD4 lymphocyte count of 88.6 cells/ mm3. These 72 patients were similar to the larger study population in age (mean age, 35.7 vs. 33.8 years), sex (61.1% vs. 59.1% female), HIV-1 seropositivity (81.9% vs. 86.6%), and ARV status (13.9% vs. 10.6% ARVs prescribed). Fifty-nine (81.9%) of 72 evaluated patients were infected with HIV-1. The in-hospital mortality rate was 25.7% (18 of 70), and the in- and outpatient mortality at 30 days was 41.6% (30 of 72). PWBL was positively associated with in-hospital but not outpatient mortality (p <.001). The receiver operating characteristic (ROC) area under the curve for PWBL was 0.81 (p <.001). The optimal PWBL concentration for predicting in-hospital mortality (sensitivity, 88.3%; specificity, 71.2%) was ≥4.0 mmol/L. Patients with a PWBL concentration ≥4.0 mmol/L died while in the hospital substantially more often (50.0%) than did those with a PWBL concentration <4.0 mmol/L (7.5%) (odds ratio, 12.3; 95% confidence interval, 3.5-48.9; p <0.001). SLSL levels were lower among survivors than among deceased. The ROC under the curve for predicting in-hospital mortality was 0.72 (p=0.004). SLSL results were inconsistent and less predictive of mortality than were those of PWBL.
The authors conclude that PWBL testing can quickly identify patients who require immediate interventions, and it should be included in evaluation and treatment algorithms for septic patients. PWBL testing could be used in village health posts, for earlier transfer of septic patients to facilities with a higher level of care, and in referral hospitals, for triage of patients to acute care settings where appropriate resuscitation can begin.
This observational study was of fair quality. The sample size was adequate and the duration of follow-up sufficient. Data were available only for 72 of the 100 enrolled patients and there was a 15% lost to follow-up among the discharge patients. Generalizability is limited to resource constrained areas and populations with high HIV prevalence. The cost of PWBL was not addressed.
Elevated lactate concentrations and poor clearance of lactic acid are known to increase mortality from severe sepsis. Lactate concentrations, combined with other laboratory measures, are used to guide early management of sepsis. Measurement of lactate concentration in developing countries is difficult because of limited resources. An effective, inexpensive method to measure lactate concentration without sophisticated laboratory resources has the potential to offer a method to identify patients in greatest need of rapid, aggressive treatment of sepsis.
The use of the PWBL and its value in predicting mortality from sepsis in populations with high prevalence of HIV has potential to assist health care workers in resource limited settings in prioritizing these patients. Hospitalization, availability of support for potential multisystem failure, and rapid administration of antimicrobial agents can be delivered more urgently in persons with high lactate concentrations.