Intensity of hemoperfusion in acute paraquat-poisoned patients and analysis of prognosis

Abstract

To evaluate the influence of different hemoperfusion (HP) intensity on 7-day and 28-day mortality for patients with paraquat (PQ) poisoning, and examine the factors that may affect the decision of the clinicians to prescribe a high intensity HP. A retrospective cohort study was conducted. The patients admitted to the department of critical care medicine of Anhui Provincial Hospital Affiliated to Anhui Medical University with the diagnosis of PQ poisoning from August 2012 to August 2014, fulfilling the following criteria were enrolled in the study: older than 18 years, interval from ingestion PQ to hospital admission shorter than 12 hours, and receiving HP treatment within 24 hours, and expecting surviving time exceeding 24 hours after admission, and data of the patients available for at least 28 days after admission. Depending on the intensity of HP, patients were assigned to either lower intensity HP group (LHP, defined as receiving HP for less than 4 hours, 2 columns) or higher intensity HP group (HHP, defined as receiving HP longer than 6 hours, 3 columns). Patients' data were retrieved from hospital's electronic database after hospital admission, and the results at 7th day and 28th day were recorded. Multiple logistic regression model was used to determine factors with which the clinician decided to choose the intensity of HP for the patients, and Cox regression model was used to evaluate 7-day and 28-day mortality. Data of 60 patients was finally available for this study. LHP group consisted of 28 patients, with a 7-day mortality of 53.6% ( 15 patients ) and 28-day mortality of 64.3% ( 28 patients ); 32 patients were assigned to HHP group with 7-day mortality of 43.8% ( 14 patients) and 28-day mortality of 62.5% (20 patients). Twenty-eight patients constituted as the HHP group, with higher PQ concentration in plasma, higher incidence of respiratory alkalosis and acute kidney injury (AKI), and higher level of lactate (Lac) compared with LHP group. However, a lower 7-day mortality was observed in the HHP group. Multiple logistic regression model indicated that at admission, interval from ingestion PQ to hospital admission longer than 4 hours [ odds ratio (OR) = 1.461, 95% confidence interval (95%CI) = 1.132-1.435, P < 0.001], younger than 50 years old (40-49 years old: OR = 1.397, 95%CI = 1.251-1.703, P = 0.002; < 40 years old: OR = 1.701, 95%CI = 1.253-1.836, P < 0.001), PQ plasma concentration ≥ 2 mg/L (OR = 3.140, 95%CI = 1.511-3.091, P < 0.001), white blood cell (WBC) > 10 × 10⁹/L (OR = 1.222, 95%CI = 1.032-1.275, P = 0.018), Lac > 2.0 mmol/L (OR = 2.392, 95%CI = 2.090-2.734, P < 0.001 ), AKI on admission (stage 2: OR = 2.350, 95%CI = 2.160-3.910, P < 0.001; stage 3: OR = 2.821, 95%CI = 1.932-3.651, P < 0.001), accompanying hypoxia (OR = 2.420, 95%CI = 2.131-2.662, P = 0.003 ) were more likely to receive higher intensity of HP. Furthermore when compared with patients survived for 28 days, patients who were older, with higher levels of PQ concentration at admission or after 4 hours of HP, accompanied by AKI, increased serum creatinine (SCr), WBC, Lac, and acute physiology and chronic health evaluation II (APACHEII) score, lower arterial partial pressure of carbon dioxide (PaCO₂) and lower pH value were more likely to die. After adjusted for con-variables in COX regression model, HHP was associated with lower 7-day mortality after admission [ hazard ratio (HR) = 0.843, 95%CI = 0.732-0.971, P = 0.032], but devoid of lowering effect on 28-day mortality rate (HR = 0.930, 95%CI = 0.632-1.411, P = 0.423). In addition, age > 50 years old (HR = 1.282, 95%CI = 1.050-1.530, P = 0.043), PQ concentration increased by 1 mg/L (HR = 2.521, 95%CI = 2.371-3.825, P = 0.012), AKI on admission (HR = 3.850, 95%CI = 2.071-5.391, P < 0.001), WBC>10 × 10⁹/L (HR = 1.932, 95%CI = 1.782-2.171, P = 0.006 ), Lac > 2.0 mmol/L ( HR = 2.981, 95%CI = 2.210-3.792, P = 0.002 ), and PaCO2 < 35 mmHg ( HR = 1.772, 95%CI = 1.483-2.516, P = 0.008; 1 mmHg = 0.133 kPa ) were independent risk factors for 28-day mortality. Though HHP was helpful in lowering mortality rate in patients with PQ poisoning within 7 days, it did not influence on 28-day mortality. Clinicians' decisions on HP intensity need further investigation, and more perfect clinical evaluation system is required for reasonable use of expensive medical resources such as HP.