Letters to the Editor
Reader Asks About Potassium Filters
To the Editor
I was reading the article “Preventing Pediatric Transfusion-Associated Incidents of Hyperkalemic Cardiac Arrest”. I personally was involved with an intraoperative hyperkalemic arrest due to massive transfusion in liver transplant case. Following the case, I’ve researched and found that potassium reducing filters are developed in Japan that seem to be effective and relatively low budget technique to reduce potassium load during transfusion with some limitations to the number of units. I noted that the authors of the above article did not mention this relatively simple method. I have no commercial interest in the any company involved in production or development of those filters.
Stefan Hariskov, MD Tufts University School of Medicine Boston, MA
Dear Dr. Hariskov:
Thank you for your letter. We did not mention potassium-reducing filters because such devices are not currently approved for use in the United States. However, in our review article1 published in Transfusion in January 2014, we did consider such filters as possible future options. Dr. Heitmiller2 was involved in the in vivo study that you referenced in your letter. The study showed that while the potassium absorption filters worked optimally for RBC units with a hematocrit of 55 to 65%, which is in the range of Additive Solution 3 (AS-3) preserved units used in the study, it was not the case for citrate-phosphate-dextrose-adenine (CPDA-1) preserved units which have a higher hematocrit of less than 80%. Blood Bank policies vary institution by institution but generally CPDA-1 units are reserved for neonatal transfusion. Certainly, a growing awareness and demand for such devices in the anesthesiology and transfusion medicine community will hopefully encourage filter manufacturers to develop and obtain approval for clinical use in the United States.
Factors Affecting Post-transfusion Potassium Level and Efficacy of Washing PRBCs
To the Editor
I read with interest the June 2014 APSF Newsletter article by Drs. Lee and Heitmiller3 regarding transfusion-associated hyperkalemic cardiac arrest in pediatric patients. Although a study performed over a decade ago focused upon pediatric patients receiving transfusions during cardiopulmonary bypass (CPB) rather than massive transfusion, perhaps our results will be of interest to some of your readers, as we observed that storage time of packed red blood cells (PRBCs) was a general but not reliable predictor of the degree of increase in serum potassium (K+) post-Tx.
Our pediatric cardiac surgery team observed cases of severe hyperkalemia post-Tx of PRBCs during CPB associated with decreased cardiac function or ventricular fibrillation, leading to increased CPB times. While washing PRBCs prior to Tx is an effective alternative to avoid this problem, washed units are more costly, contain fewer PRBCs, and have only a 24-hr shelf life.
Dr. Pearl Toy, then the director of the blood bank at the University of California San Francisco Medical Center, and I undertook a prospective unblinded observational study to help determine when washed PRBCs were indicated. We measured the effect of transfusion during CPB of one unit of banked RBCs on serum K+ following 103 transfusions to 99 patients weighing <15kg. (The median patient weight was 5.6 Kg, ranging from 1.5-14.9 Kg.) Electrolyte concentrations were measured <15 min. prior to and 5-15 min. post-Tx, nearly always toward the end of CPB in preparation for separation from bypass. We did not alter usual practices during CPB including the addition of calcium and sodium bicarbonate.
For the unwashed units (n=75), the mean increase in K+ was 1.05 ± SD 0.92. While we observed a trend correlating the absolute increase in post-transfusion K+ with increased days of storage and previous irradiation, a storage time of only 2-5 days did not prevent individual cases of extreme hyperkalemia. Among the 26 transfusions following only 2-5 days PRBC storage we observed one increase in K+ of 2.6 mEq/L resulting in a post-transfusion K+ of 7.5. Individual increases in serum K+ of >2.4 mEq/L occurred in each of 4 storage-time categories (2-5, 6-10, 11-20, and 21-30 days). The strongest observed predictor of both the absolute post-Tx K+ level and the increase was the pre-Tx K+ value. Other predictors were patient age < 1 year, increased days of blood storage, and irradiation of the unit.
As expected, no significant increase in serum K+ following Tx of washed units (n=28) was observed. The mean increase was 0.07 mEq/L ± SD 0.59. (Mann-Whitney P < 0.0001 compared with unwashed units.)
Our conclusions were that transfusion during CPB of washed PRBCs was indicated for patients <1 yr of age when normal cardiac rhythm was essential. These data were presented at the American Society of Hematology meeting in San Francisco in 2000.4
Lydia Cassorla, MD, MBA, Professor Emeritus, Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA
Dear Dr. Cassorla,
Thank you for sharing your study with us. Your findings that the strongest predictor of post-transfusion potassium rise and absolute level was the pretransfusion potassium level, and that individual increases in serum potassium levels of greater than 2.4 mEq/L occurred in each of the 4 storage time categories (2-5, 6-10, 11-20 and 21-30 days) are particularly interesting. They reinforce the point that transfusion associated hyperkalemia has multiple contributing factors outside of the storage age of the transfused blood. I would like to also point out to our readers a related article by Swindell et al.5 where washing irradiated RBCs significantly reduced potassium levels in cardiopulmonary bypass prime in infants undergoing complex congenital heart surgery.
Clarification of Dextrose Dose for Infants
To the Editor
Shouldn’t the dextrose dose be 1-2 ml/kg vs 1-2 Gm/kg? I would not want to give a 3 kg infant 60 ml of D10W? D10W is 100 mg dextrose/ml.
Tammy Dukatz, CRNA, Beaumont Health System, Royal Oak, MI
Dear Ms. Dukatz:
Thank you for your letter. It gives us an opportunity to clarify. The dextrose dose for treating hyperkalemia is correctly written in the article in g/kg rather than mL/kg, but the 1-2 g/kg is a bit high and more appropriate for the emergency treatment of hypoglycemia rather than in conjunction with insulin for hyperkalemia treatment. We were attempting to streamline the dosages cited by different sources. Coté et al.’s A Practice of Anesthesia for Infants and Children6 prescribes the following: dextrose 0.5-1 g/kg and insulin 0.1 units/kg to be given over 30-60 minutes. The 1-2 mL/kg dose applies if D50W is used because 1 mL of D50W contains 500mg (0.5g) of dextrose. The maximum dose is the adult dose of 25-50 g dextrose and 5-10 units of regular insulin.7
- Lee AC, Reduque LL, Luban NLC, Ness PM, Anton B, Heitmiller ES. Transfusion-associated hyperkalemic cardiac arrest in pediatric patients receiving massive transfusion. Transfusion 2014; 54: 244-54.
- Yamada C., Heitmiller ES, Ness PM, King KE. Reduction in potassium concentration of stored blood cell units using a resin filter. Transfusion 2010; 50; 1926-33.
- Lee AC, Heitmiller ES. Preventing pediatric transfusion-associated incidents of hyperkalemic cardiac arrest. A wake up safe quality improvement initiative. APSF Newsletter 2014;29:1,6.
- Cassorla L, Ho RJ, Watson JJ, Toy PTCY. Increase in serum potassium after red blood cell transfusion during cardiopulmonary bypass in pediatric patients. Blood 2000;96:452a.
- Swindell CG, Barker TA, McGuirk SP, Jones TJ, Barron DJ, Brawn WJ, Horsburgh A, Willetts RG. Washing of irradiated red blood cells prevents hyperkalaemia during cardiopulmonary bypass in neonates and infants undergoing surgery for complex congenital heart disease. Eur J Cardiothorac Surg 2007;31:659-64.
- Charles Coté M, Jerrold Lerman M, Brian Anderson M. Coté And Lerman’s A Practice Of Anesthesia For Infants And Children [e-book]. Elsevier Health Sciences; 2013. Available from: R2 Digital Library, Ipswich, MA. Accessed September 5, 2014.
- Ronald Miller M. Miller’s Anesthesia, 2 Vol Set [e-book]. Elsevier Health Sciences; 2010. Available from: R2 Digital Library, Ipswich, MA. Accessed September 6, 2014.