Clinical Evaluation of Subcutaneous Lactate Measurement in Patients after Major Cardiac Surgery

Minimally invasive techniques to access subcutaneous adipose tissue for glucose monitoring are successfully applied in type1 diabetic and critically ill patients. During critical illness, the addition of a lactate sensor might enhance prognosis and early intervention. Our objective was to evaluate SAT as a site for lactate measurement in critically ill patients. In 40 patients after major cardiac surgery, arterial blood and SAT microdialysis samples were taken in hourly intervals. Lactate concentrations from SAT were prospectively calibrated to arterial blood. Analysis was based on comparison of absolute lactate concentrations (arterial blood vs. SAT) and on a 6-hour lactate trend analysis, to test whether changes of arterial lactate can be described by SAT lactate. Correlation between lactate readings from arterial blood vs. SAT was highly significant (r2 = 0.71, P < .001). Nevertheless, 42% of SAT lactate readings and 35% of the SAT lactate trends were not comparable to arterial blood. When a 6-hour stabilization period after catheter insertion was introduced, 5.5% of SAT readings and 41.6% of the SAT lactate trends remained incomparable to arterial blood. In conclusion, replacement of arterial blood lactate measurements by readings from SAT is associated with a substantial shortcoming in clinical predictability in patients after major cardiac surgery

Secukinumab Distributes into Dermal Interstitial Fluid of Psoriatic Patients as Demonstrated by Open Flow Microperfusion

Secukinumab is a monoclonal antibody targeting IL-17A for treatment of inflammatory diseases, including skin diseases like psoriasis. However, measuring the antibody concentrations at the target site, the skin, still holds challenges with existing methods. This clinical study (NCT01539213) used the minimally invasive dermal open flow microperfusion (dOFM) method to assess the concentration of secukinumab in the dermal interstitial fluid (ISF). Measurements were performed in the skin of eight healthy subjects and in non-lesional and lesional skin of eight psoriatic subjects after a single 300 mg subcutaneous dose of secukinumab on Day 1. In healthy subjects, the secukinumab concentration in skin on Days 8 and 15 was about 23% of that measured in serum (36.1 and 35.0 µg ml-1 on Days 8 and 15, resp.). Secukinumab concentrations in non-lesional and lesional skin of psoriatic patients were comparable to each other. They were between 28% and 39% of the concentration measured in serum (21.2 µg ml-1). The dermal ISF concentrations obtained from dOFM in healthy subjects is supported by data from punch biopsies and suction blisters. This study demonstrated that dOFM is a useful technique to assess therapeutic antibody concentrations in the skin. Secukinumab was found in skin rapidly after s.c. injection and achieved levels in the skin sufficient to neutralize free IL-17A locally