Severe Metformin Poisoning Successfully Treated with Simultaneous Venovenous Hemofiltration and Prolonged Intermittent Hemodialysis.

Metformin poisoning is a life-threatening condition with a high mortality rate. We present a patient case of metformin poisoning following intake of 80 g metformin resulting in severe lactate acidosis with a nadir pH of 6.73 and circulatory collapse, successfully treated with addition of prolonged intermittent hemodialysis (HD) to continuous venovenous hemofiltration (CVVH). The patient's pH became normal 48 hours after metformin ingestion during simultaneous CVVH and addition of 22 hours of intermittent HD in the ICU. The highest metformin level was found to be 991 µmol/L (therapeutic range 3.9-23.2 µmol/L). We conclude that in cases of severe metformin poisoning with circulatory shock and extreme lactic acidosis, the usual CVVH modality might not efficiently clear metformin. Therefore, additional prolonged HD should be considered even in the state of cardiovascular collapse with vasopressor requirement.

Keep Ventilating the Lungs While the Heart is Still Ejecting on Femoro-femoral Cardiopulmonary Bypass.

Femoro-femoral cardiopulmonary bypass (CPB) followed by deep hypothermic circulatory arrest is one of the modalities used for ascending aortic pseudoaneurysm repair to achieve cardiac unloading and to avoid severe hemorrhage due to the risk of rupture during the sternal entry. However, due to the limited size of the cannulas, it can be challenging to achieve total cardiopulmonary support. Therefore, despite the achievement of total cardiopulmonary support, the heart may still be able to eject antegrade blood flow that meets the retrograde blood flow from the arterial side of the CPB. The point where the blood flow meets in the aorta is called the watershed area. If the antegrade blood flow is large due to a left ventricular ejection, the watershed area will be located in the descending aorta. Therefore, if ventilation is stopped, deoxygenated blood will be ejected to the cerebral circulation. Cerebral near-infrared spectroscopy (NIRS) may be used as a noninvasive and continuous measurement of regional brain oxygen saturation (rSO2). This case demonstrates that cerebral desaturation due to discontinued mechanical ventilation, when the heart was still ejecting during the initial phase of femoro-femoral CPB, immediately was detected by a pronounced drop bilaterally: In the left frontal lobe, rSO2 fell from 56% to 21%, and in the right frontal lobe it fell from 47% to 25%. The authors recommend monitoring cerebral saturation using NIRS in the case of femoro-femoral CPB.

Colloids in Cardiac Surgery-Friend or Foe?

OBJECTIVE: The right choice of fluid replacement still is a matter of debate. Recently, two large-scale studies on the use of hydroxyethyl starches (HES) in the intensive care setting have been published, which have caused a huge shift in the daily practice of volume therapy. These results have been applied to patients outside intensive care. The aim of this study was to evaluate the impact this change has had on the outcomes in a large population of cardiac surgery patients, with a focus on the type of colloid infusion. DESIGN: A prospective, registered, observational study, using propensity score matching. SETTING: Cohort study from 3 university hospitals using a common registry. PARTICIPANTS: The study comprised 17,742 patients who were referred for cardiac surgery from 2007 to 2014. INTERVENTIONS: Patients were divided in groups according to perioperative fluid replacement with either crystalloids or colloids. The colloid group was further divided into HES or human albumin (HA). Analyses were based on the following 3 subsections: HES versus crystalloids, HA versus crystalloids, and HES versus HA, with use of propensity score matching or direct matching of cases. Primary outcome parameters were 30-day and 6-month mortality, new postoperative renal replacement therapy, and new cardiac ischemic events. MEASUREMENTS AND MAIN RESULTS: The groups were fully comparable in individual analyses. The use of HES had no impact on new dialysis and 30-day mortality. A Cox proportional regression analysis showed that HES had no impact on 6-month mortality and new postoperative ischemic events. When comparing HA with crystalloid use, a significantly increased risk in crude analysis was demonstrated on all outcome parameters; and when comparing HA with HES, a significantly higher risk was observed in HA patients in mortality parameters and new postoperative, but after adjustment, only the risk of new postoperative dialysis persisted. CONCLUSION: This study underlined the difficulties in establishing hardcore outcome data, even in large cohort studies. The findings seemed to diminish the magnitude of risk when using HES in cardiac surgery patients and seriously questioned the choice of HA when a plasma expander is needed.