Case Report
A 78 yr-old obese man (usual body weight 110 Kg, BMI 35
kg/m2) was admitted to the Renal Intensive Care Unit
(ICU) for oliguric AKI on stage 3b CKD (usual serum creatinine [Scr]
concentration, 2 mg/dL, CKD-EPI eGFR 32.6 mL/min/1.73
m2) associated with septic shock due to newly
diagnosed infective endocarditis. His drug treatment included
pregabalin, 50 mg twice daily, for severe neuropathic pain secondary to
diabetic neuropathy. On admission, he complained of severe dyspnea and
fatigue. Physical examination revealed a pyretic 118-Kg oliguric patient
with severe peripheral edema and diffuse basal pulmonary rales. Blood
pressure was 105/70 mmHg while on norepinephrine 16 mcg/min, with pulse
rate 100 beats/min. Breaths were 28/min, with peripheral oxygen
saturation at 97% while on non-invasive mechanical ventilation (BPAP
modality, PSV 12 cmH2O, PEEP 8 cmH2O,
FiO2 50%). APACHE II score was 30. Laboratory findings
showed a stage 3 AKI with mild metabolic acidosis. Given the persistent
oliguria associated with severe fluid overload unresponsive to the
high-dose loop diuretic therapy and hemodynamic instability, KRT was
started as Continuous Venovenous Hemodiafiltration (CVVHDF) with
regional citrate anticoagulation (RCA), using the Prismax system (Baxter
Renal Care, USA) and a polyacrylonitrile AN69 hemofilter (ST 150, 1.5
m2, Baxter Renal Care, USA). A low concentration
citrate solution (18 mmol/L; Regiocit, Baxter) was combined with a
phosphate-containing solution, used as both dialysis and post-dilution
replacement fluid (Biphozyl, Baxter) for a prescribed dialysis dose of
30 ml/Kg/h. Three days after, given the slow but progressive improvement
of fluid overload, KRT modality was shifted to Sustained Low-Efficiency
Dialysis (SLED) by using the same system and the same dialysis
solutions, with a prescribed effluent volume of 100 ml/min. On the
fourth ICU day, patient’s hemodynamic status definitely improved, and
KRT was thereafter continued as every other day conventional
Intermittent Hemodialysis (IHD).
Given the reported neuropathic pain and aiming at reducing opioids
consumption, chronic therapy with pregabalin was confirmed. Moreover,
given the expected extracorporeal clearance, the prescribed pregabalin
dose was increased at KRT start to 75 mg every 12 hours.
The evaluation of TDM of pregabalin in course of different KRT
modalities was performed by Liquid Chromatography coupled with tandem
mass spectrometry (LC-MS/MS system) (Shimadzu Italia, Milano)
(Supplemental Material 1 ) [11]. At the same dose
administered (75 mg every 12 hours) a progressive reduction of
pregabalin serum levels in course of prolonged KRT modalities (CKRT and
SLED) was observed, while a rapid decrease was observed during IHD with
a negligible post treatment rebound (Figure 1 ).