Hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers on the day of prone positioning spinal surgery in elderly patients.

Introduction: The hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers (ARBs) before surgery in elderly patients undergoing spinal surgery in a prone position during anesthesia induction to skin incision are still unknown. Methods: In this prospective study, 80 patients undergoing spinal surgery in a prone position with general anesthesia, aged 60-79 years, American Society of Anesthesiologists (ASA) II or III, were enrolled. Patients who had ARBs only in their preoperative medication list were randomly divided into two groups at a 1:1 ratio: In Group A, ARBs were continued on the morning of surgery, while in Group B, they were withhold. Norepinephrine was infused to maintain the blood pressure at the baseline level of ±20% during anesthesia induction in all patients. The primary outcome was the consumption of norepinephrine in each group from anesthesia induction to skin incision. The secondary outcomes include changes in invasive arterial blood pressure and heart rate, the fluid infusion volumes, the amounts of anesthetic drugs, and the total time from induction to skin incision. Results: There were no significant differences in the demographics, the fluid infusion volumes, the amounts of anesthetic drugs, the total time from induction to skin incision, and hemodynamics at different time points (p > 0.05), while significant differences were found in norepinephrine consumption between the two groups (p < 0.001). Compared with Group B, the consumption of norepinephrine increased significantly in Group A (93.3 ± 29.8 vs. 124.1 ± 38.7 µg, p = 0.000). In addition, the same trend was illustrated in the pumping rate of norepinephrine between Group B (0.04 ± 0.01 µg·kg-1·min-1) and Group A (0.06 ± 0.02 µg·kg-1·min-1) (p = 0.004). Conclusion: Our study conducted in elderly patients with hypotension undergoing prone spinal surgery demonstrated a greater pumping rate of norepinephrine during anesthesia induction in patients with ARBs continuing before surgery than those withholding, indicating that it was more difficult to maintain hemodynamic stability.Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=141081, ChiCTR2100053583.

catena-Poly[[[diaqua-iron(II)]-µ-pyridine-2,5-dicarboxyl-ato-[tetra-aqua-iron(II)]-µ-pyridine-2,5-dicarboxyl-ato] tetra-hydrate].

In the crystal structure of the title compound, {[Fe(2)(C(7)H(3)NO(4))(2)(H(2)O)(6)]·4H(2)O}(n), there are two types of coordination for the Fe(II) atoms. One Fe(II) atom is in a distorted octa-hedral N(2)O(4) environment, with two chelating rings from the pyridine-dicarboxyl-ate ligands and two O atoms from the water mol-ecules, while the other is in a distorted octa-hedral O(6) environment with two O atoms from the pyridine-dicarboxyl-ate ligands and four O atoms from the water mol-ecules. Both Fe(II) atoms lie on crystallographic centers of symmetry. The complex possesses an infinite chain structure running along the [101] direction. These chains are inter-connected by the uncoordinated water mol-ecules through O-H⋯O hydrogen bonds.

catena-Poly[[[diaqua-iron(II)]-µ-pyrazine-2,3-dicarboxyl-ato] dihydrate].

The crystal structure of the title compound, {[Fe(C(6)H(2)N(2)O(4))(H(2)O)(2)]·2H(2)O}(n), was synthesized by a diffusion method. It has a one-dimensional polymeric chain structure and the chains are further connected into a three-dimensional structure by hydrogen bonds. The Fe(II) ion has a distorted octa-hedral coordination environment, with two N and two O atoms from the pyrazine-2,3-dicarboxyl-ate ligands in the equatorial plane and with two water mol-ecules in axial positions. The Fe atom lies on a crystallographic centre of symmetry and a twofold rotation axis passes through the pyrazine ring.

[Polarographic behavior and determination of glimepiride].

AIM: To establish a polarographic method of parallel catalytic hydrogen wave for determination of glimepiride. METHODS: The catalytic wave of glimepiride in the presence of K2S2O8 was used to improve the analytical sensitivity. The rapid determination of glimepiride was done by linear single sweep polarography. RESULTS: The catalytic hydrogen wave of glimepiride was measured at ca. -1.36 (vs SCE) in 0.09 mol x L(-1) Na2B4O7-KH2PO4 (pH 6.24 +/- 0.1) supporting electrolyte. When 1.0 x 10(-2) mol x L(-1) K2S2O8 was present, the current increased by 25 times, and the peak potentioal was unchanged, producing a more sensitive parallel catalytic hydrogen wave. The peak current of the parallel catalytic hydrogen wave was rectilinear to the glimepiride concentration in the range 1.0 x 10(-7) - 4.2 x 10(-5) mol x L(-1) (r = 0.9990, n = 9). The detection limit was 5.0 x 10(-8) mol x L(-1). CONCLUSION: The proposed method could be applied to the determination of glimepiride in pharmaceuticals without preliminary separation.

Polarographic behavior of cephalexin and its determination in pharmaceuticals and human serum.

Cephalexin gives a reduction wave in 0.03 mol/l HCl medium at ca. -1.24 V. With cephalexin concentration higher than 2.5 x 10(-5) mol/l, another reduction wave is observed at ca. -0.90 V. These reduction waves are attributed to the reduction of ethylenic bond of a six-membered dihydrothiazine ring. When H2O2 is present, the reduction wave at ca. -0.90 V is catalyzed by H2O2 and its reduction intermediate hydroxyl radical *OH, producing a catalytic wave. However, the reduction wave at ca. -1.24 V remains nearly unchanged. A sensitive polarographic method for the determination of cephalexin is proposed based on the reduction wave of cephalexin. The second-order derivative peak current of the wave at ca. -1.24 V is rectilinear to the cephalexin concentration in the range 1.0 x 10(-7) to 2.5 x 10(-5) mol/l, and the detection limit is 5.0 x 10(-8) mol/l. The proposed method is applied to the individual tablet dosage form and human serum.

[Polarographic catalytic wave of clarithromycin and its applications].

AIM: To develop a new method for the determination of clarithromycin. METHODS: The catalytic wave of clarithromycin in the presence of K2S2O8 was used for improving the analytical sensitivity. The rapid determination of clarithromycin has been carried out by linear single sweep polarography. RESULTS: The reduction wave of clarithromycin appeared at ca. -0.79 V (vs SCE) in 0.24 mol x L(-1) KH2PO4-Na2HPO4 (pH 6.81) supporting electrolyte, which was ascribed to the reduction of carbonyl group on C-9 position. In the presence of 0.01 mol x L(-1) K2S2O8, the reduction wave was catalyzed to produce a parallel catalytic wave. The peak current of the catalytic wave was ca. Twenty times higher than that of the corresponding reduction wave. Based on the catalytic wave, a new method for the determination of clarithromycin has been proposed. The peak current of the catalytic wave was rectilinear to clarithromycin concentration in the range of 4.0 x 10(-7)-5.0 x 10(-5) mol x L(-1). The detection limit was 2.0 x 10(-7) mol x L(-1). CONCLUSION: The proposed method could be used for the direct determination of clarithromycin in pharmaceuticals and urine without preliminary separation.