Using the Seraph® 100 Microbind® Affinity blood filter under slow flow conditions through 18 G and 16 G central lines.

INTRODUCTION: The Seraph® 100 Microbind® Affinity blood filter (Seraph® 100) has been in use since 2019 for the treatment of fulminant or difficult to treat blood stream infections as an adjunct to pharmacotherapy. In 2020 the device received emergency use authorization by the US Food and Drug Administration for the treatment of critically ill COVID-19 patients with confirmed or imminent respiratory failure. Results of an international registry showed that the Seraph® 100 was operated under blood flow rates of 100-350 mL/min. As those conditions require a large bore central line, a dialysis catheter is currently considered indispensable to operate the Seraph® 100. The use of smaller catheter lumina has neither been evaluated in vitro nor in vivo. METHODS: In vitro pressure data before and after the Seraph® 100 at various blood pump rates (prepump line 16 G, postpump line 18 G) with saline and human plasma were obtained. Further, anecdotal flow and pressure data of two patients treated with the Seraph® 100 for a COVID-19 infection are reported. RESULTS: At a pump speed of 50 mL/min pre-Seraph® pressure using saline was -70 [-70 to -60] mm Hg. In comparison, using plasma pre-Seraph® pressure was lower at -120 [-120 to -105] mm Hg; p < 0.001 (t-test). The post-Seraph® pressure at 50 mL/min using saline of 120 [110-130] mm Hg was not different from plasma at 130 [120-140] mm Hg, p = 0.152 (t-test). Blood flow rates of 50 mL/min did not lead to preAP levels below -250 mm Hg in the two clinical cases. CONCLUSION: Seraph® 100 blood flow rate of 50 mL/min may be achieved using low flow vascular access, allowing to treat a blood volume 72 L in 24 h.

More Drug Monitoring and Less CT Scans of the Brain: Gabapentin Overdose in Two Peritoneal Dialysis Patients.

In parallel with the decline of renal excretory function, drug dosing of many drugs becomes more challenging. Finding the right dose is even more difficult if kidney replacement therapy is instituted. This is further aggravated by the fact that even for substances with a narrow therapeutic range, drug monitoring is only rarely offered, let alone advocated. This holds also true for gabapentin, an anticonvulsant drug that is increasingly prescribed for indications such as cancer-related pain, restless legs syndrome, migraine, or uremic pruritus. The drug is excreted unchanged in urine, so plasma clearance of gabapentin is directly proportional to creatinine clearance. Hence, renal impairment reduces gabapentin excretion and increases plasma gabapentin concentrations in a linear fashion. Therefore, the elimination half-life of gabapentin is between 5 and 9 h, in patients with normal renal function but increases to 132 h in patients on dialysis. Epidemiological data from the USRDS underline this problem. About 19% of the 140,899 adult USA patients enrolled in Medicare coverage received gabapentin in 2011. Its use was associated with an increased risk of altered mental status, fall, and fracture. We report 2 patients in which overdose of gabapentin occurred. In 1 patient, severe neurological symptoms prompted an extensive diagnostic work up, while the underlying cause of the clinical presentation was a supra-therapeutic drug level of gabapentin. Consequently, symptoms subsided with the discontinuation of the drug. Indication and drug dose of gabapentin in dialysis patients should be tightly controlled, and drug monitoring used to avoid unintended overdose.

Evaluation of the ideal length of the Seldinger needle for internal jugular vein catheter placement.

Placement of central venous catheters (CVC) into the internal jugular vein represents a routine clinical intervention. The periprocedural complication rate ranges from 5 to 20% and can be reduced by ultrasound guidance, training of residents and other measures. We aimed to proof that the average Seldinger needle is too long, increasing the risk of periprocedural injury, best epitomized in the stellate ganglion injury/irritation. The first part of the study was an online market analysis to investigate the standard needle length currently offered as part of the CVC placement sets. The second part of the study involved 35 hospitalized patients (14 female; median age 74.5 years). In those the distance between the skin and the internal jugular vein as well as the diameter of the internal jugular vein was measured by ultrasound in both, supine position as well as 45° semi-sitting position. In the third part of the study 80 body donors (45 female; median age 83.0 years) preserved by the ethanol/formaldehyde method were studied. In those the distance and angle between the typical landmark for insertion of the Seldinger needle for internal jugular vein catheter placement to the stellate ganglion was measured. The median [interquartile range] Seldinger needle length was 7 [4.0-10.0] cm. In the examined patients the maximum distance between the skin and the internal jugular vein was 1.87 cm. The minimum distance was 0.46 cm and the median distance averaging supine and 45° position was 1.14 [0.94-1.31] cm. Regarding the body donors the median distance from the insertion point of the internal jugular vein to the stellate ganglion was longer in men 5.5 [4.95-6.35] cm than in women 5.2 [4.7-5.9] (p = 0.031 unpaired t-test). With 7 cm average length the Seldinger needle currently sold as part of CVC sets is long enough to physically reach the stellate ganglion, not to mention more proximal structures. A shorter needle length would be sufficient to reach the internal jugular vein even in obese patients and with a small insertion angle while minimizing the possibility to cause severe injury as structures like the pleura and the stellate ganglion could not be reached by shorter needles.