[Comparative study of dexmedetomidine vs. midazolam on plasma catecholamine levels and hemodynamics in patients with septic shock].

Objective: To compare the effects of dexmedetomidine (DEX) and midazolam on the endogenous plasma catecholamine levels and the dosage of exogenous norepinephrine (NE) to maintain blood pressure in patients with septic shock.

Methods: From January 2018 to December 2019, patients admitted to the department of critical care medicine of the Affiliated Hospital of Guizhou Medical University who needed invasive mechanical ventilation and had a stay of more than 48 hours in the intensive care unit (ICU) for septic shock and received DEX or midazolam for sedation were enrolled in this study. The hemodynamic data, arterial blood lactic acid (Lac) level, arterial blood gas analysis and vasoactive drug dose at 0, 12, 24, 48, 72 hours after entering the ICU were dynamically recorded, and the plasma catecholamine levels at 0, 24, 48 hours after entering the ICU were recorded. The acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score on ICU-admission were calculated. The parameters of prognosis were collected.

Results: A total of 24 patients were enrolled, 12 in the DEX group and 12 in the midazolam group. There were similar dynamic trends in heart rate (HR), central venous pressure (CVP), venous-arterial carbon dioxide pressure difference (Pv-aCO), oxygenation index (PaO/FiO), and Lac level of patients between the two groups. Only the 12-hour CVP and 72-hour Pv-aCO in the DEX group were significantly higher than those in the midazolam group [CVP (mmHg, 1 mmHg = 0.133 kPa): 13±3 vs. 10±3, Pv-aCO (mmHg): 9.4±5.2 vs. 4.8±2.2, both P < 0.05], and the mean arterial pressure (MAP) of patients in the DEX group at 48 hours and 72 hours was significantly higher than that in the midazolam group (mmHg: 95±10 vs. 86±10, 96±9 vs. 88±7, both P < 0.05). There was no statistically significant difference in the duration of mechanical ventilation, ICU mortality or in-hospital mortality between the DEX group and the midazolam group [duration of mechanical ventilation (days): 5.6 (3.8, 9.5) vs. 10.5 (5.9, 15.0), ICU mortality: 16.7% vs. 33.3%, in-hospital mortality: 25.0% vs. 41.7%, all P > 0.05]. There was no significant difference in the dosage of propofol or sufentanil between the DEX group and the midazolam group [propofol (mg/kg): 0 (0, 9.35) vs. 4.07 (0, 13.75), sufentanil (μg/kg): 6.26 (4.90, 9.80) vs. 8.32 (3.52, 9.34), both P > 0.05]. The levels of plasma NE, dopamine and dobutamine in the DEX group at 48 hours were significantly lower than those in the midazolam group [NE (ng/L): 1 850.12 (342.16, 2 938.05) vs. 4 596.60 (3 310.56, 5 546.84), dopamine (ng/L): 119.10 (60.47, 200.71) vs. 275.40 (214.61, 418.88), dobutamine (ng/L): 51.20 (36.85, 75.59) vs. 98.97 (85.65, 107.10), all P < 0.05], but the amount of NE required to maintain MAP between 65 mmHg and 75 mmHg in the DEX group and the midazolam group was similar [μg/kg: 1 922 (1 170, 4 887) vs. 2 466 (2 043, 3 438), P > 0.05].

Conclusions: DEX can reduce plasma catecholamine levels in patients with septic shock more than midazolam, and does not increase the dose of exogenous NE, and has a smaller effect on hemodynamics in patients with septic shock than midazolam.