Extracorporeal Filtration of Potassium in a Swine Model of Bilateral Hindlimb Ischemia-Reperfusion Injury With Severe Acute Hyperkalemia

A Novel Peritoneal Packing Method for Management of Hyperkalemia During Acute Kidney Injury in Trauma

INTRODUCTION

United States Military operations in resource limited areas are increasing. Furthermore, future peer or near-peer conflicts will require caring for larger numbers of casualties with limited resources. In this setting, traditional renal replacement therapy is not feasible and novel methods are required to address severe acute kidney injury in austere environments lacking definitive therapies. Here, we describe experiments designed to determine the efficacy of a novel peritoneal packing material (Potassium Binding Pack-PBP, CytoSorbents INC) for the acute management of severe hyperkalemia.

MATERIALS AND METHODS

Male swine (52 ±1 kg) were nephrectomized via midline laparotomy under a plane of anesthesia and randomized into one of two experimental groups (PBP & CON). Exogenous potassium was infused to achieve a serum potassium level of 7.5 mEq/L. Novel potassium absorbing packs (PBP) or sham packs (CON) were placed in the right and left upper quadrants, and the right and left paracolic gutters of the abdomen to simulate four-quadrant packing (n = 6, n = 5, respectively). Two liters of peritoneal dialysis fluid was instilled into the abdomen and temporary closure performed. Animals were observed for 12 hours. Serum and peritoneal fluid (dialysate) potassium levels were sampled at T = 15, 30, 60 min, and Q60min thereafter. Animals were humanely euthanized at the end of the observation period.

RESULTS

Baseline characteristics were similar between groups. Pairwise analysis showed that serum potassium concentrations were significantly lower in the PBP group compared to CON at T = 540 and T = 720 (P = 0.006 and P = 0.015, respectively). Potassium concentrations were significantly lower in dialysate of the PBP group compared to CON at all time points after T = 15 (T = 30, P = 0.017; T = 60 through T = 720, P < 0.001).

CONCLUSIONS

This is the first demonstration of an effective technology for the management of hyperkalemia in trauma in the absence of standard of care; renal replacement therapy. We identified that PBP was able to consistently maintain a concentration gradient between dialysate in the peritoneum and system potassium concentration throughout the experiment. Furthermore, systemic potassium concentrations were reduced in a clinically relevant manner in the PBP group compared to CON. This suggests that peritoneal packing technology for the management of metabolic disturbances in trauma has potential for clinical application. These results are preliminary and should be interpreted with caution.

Molecular Mechanisms of Rhabdomyolysis-Induced Kidney Injury: From Bench to Bedside

Rhabdomyolysis-induced acute kidney injury (RIAKI) occurs following damage to the muscular sarcolemma sheath, resulting in the leakage of myoglobin and other metabolites that cause kidney damage. Currently, the sole recommended clinical treatment for RIAKI is aggressive fluid resuscitation, but other potential therapies, including pretreatments for those at risk for developing RIAKI, are under investigation. This review outlines the mechanisms and clinical significance of RIAKI, investigational treatments and their specific targets, and the status of ongoing research trials.

Extracorporeal potassium binding for the management of hyperkalemia in an anephric model of crush injury

BACKGROUND

Potassium-binding polymers have shown promising results in an anephric porcine hyperkalemia model. The benefits of the polymer in a clinically relevant injury model remain unknown. We hypothesized that potassium-binding cartridges would control serum potassium concentration in a porcine hemorrhagic shock model with supraceliac aortic occlusion and a limb crush injury.

METHODS

Ten Yorkshire-cross swine were anesthetized and instrumented. Pigs underwent splenectomy and bilateral nephrectomy. Hemorrhagic shock was induced for 30 minutes while a leg compression device was applied. Pigs underwent supraceliac aortic occlusion for 60 minutes and were resuscitated with shed blood. The leg compression device was removed 20 minutes after balloon deflation. After 20 minutes of reperfusion, animals were randomized to extracorporeal circulation with (treatment) or without (control) the potassium binding cartridges. In both groups, blood was circulated through a hemodialyzer with a peristaltic pump. In the treatment group, the ultrafiltrate was diverted from the hemodialyzer through cartridges containing the polymer and returned to the extracorporeal circuit. Animals were resuscitated with 0.9% saline boluses and a norepinephrine infusion. The change in serum potassium concentration (ΔK) was calculated as serum [K]T390 - serum [K]T0.

RESULTS

There was a significant difference in serum potassium concentration between groups (p < 0.001). ΔK was significantly higher in the control than the treatment group (3.75 [3.27-4.42] and 1.15 [0.62-1.59] mmol/L, respectively; p = 0.03). There were no differences in mean arterial pressure (p = 0.14), isotonic crystalloids requirement (p = 0.51), or norepinephrine dose (p = 0.83) between groups. Serum lactate concentration was significantly higher in the control group (p < 0.001). At the end of the experiment, the [K] was reduced by 25% (24.9%-27.8%) across the cartridges.

CONCLUSION

The cartridges controlled serum potassium concentrations without dialysate and retained potassium binding capabilities over 4 hours. There were no deleterious effects on hemodynamic parameters. Those cartridges might be beneficial adjuncts for hyperkalemia management in austere environments.

LEVEL OF EVIDENCE

Translational science study, level I.

A Novel Perfusion System for Damage Control of Hyperkalemia in Swine

INTRODUCTION

The standard of care for refractory hyperkalemia is renal replacement therapy (RRT). However, traditional RRT requires specialized equipment, trained personnel, and large amounts of dialysate. It is therefore poorly suited for austere environments. We hypothesized that a simplified hemoperfusion system could control serum potassium concentration in a swine model of acute hyperkalemia.

METHODS

Ten pigs were anesthetized and instrumented. A dialysis catheter was inserted. After bilateral nephrectomy, animals received intravenous potassium chloride and were randomized to the control or treatment group. In both groups, blood was pumped through an extracorporeal circuit (EC) with an in-line hemodialyzer. In the treatment arm, ultrafiltrate from the hemodialyzer was diverted through cartridges containing novel potassium binding beads and returned to the EC. Blood samples were obtained every 30 min for 6 h.

RESULTS

Serum potassium concentration was significantly lower in the treatment than in the control group over time (P = 0.02). There was no difference in serum total calcium concentration for group or time (P = 0.13 and 0.44, respectively) or platelet count between groups or over time (P = 0.28 and 1, respectively). No significant EC thrombosis occurred. Two of five animals in the control group and none in the treatment group developed arrhythmias. All animals survived until end of experiment.

CONCLUSIONS

A simplified hemoperfusion system removed potassium in a porcine model. In austere settings, this system could be used to temporize patients with hyperkalemia until evacuation to a facility with traditional RRT.