Revisión sistemática y metaanálisis de los efectos hemodinámicos del etomidato frente a otros sedantes en pacientes sometidos a secuencia de intubación rápida / A systematic review and meta-analysis of the hemodynamic effects of etomidate versus other sedatives in patients undergoing rapid sequence intubation

Introducción: La secuencia de intubación rápida es una técnica de protección y rescate de la vía aérea que requiere el uso de sedantes para propiciar un adecuado escenario durante la intubación orotraqueal. Son utilizados diferentes sedantes inductores, siendo el etomidato el más común por sus cualidades farmacocinéticas y farmacodinámicas, donde resalta su estabilidad hemodinámica. Sin embargo, en comparación con otros sedantes esta superioridad es controvertida. Materiales y métodos: Se realizó un metaanálisis con un protocolo definido a priori y siguiendo las etapas de la guía PRISMA. Se calculó la diferencia de medias de la presión arterial sistólica antes y después de la administración del sedante, además de un metaanálisis de riesgos relativos de hipotensión. Resultados: Se incluyeron 10 estudios en los cuales la incidencia de hipotensión en el grupo de pacientes que recibió el etomidato osciló entre el 6,4% y el 75,2%, mientras que en los que recibieron otros sedantes osciló entre el 24,0% y el 65,9%. En los metaanálisis de diferencia de medias no se hallaron diferencias significativas de la presión arterial sistólica durante la preintubación 0,01mmHg (IC 95%: –0,90; 0,92), ni en la postintubación 0,98mmHg (IC 95%: –0,24; 2,20). Además, el metaanálisis de riesgos relativos indica que el riesgo de hipotensión es igual a un RR 1,19 (IC 95%: 0,92-1,54) entre quienes recibieron el etomidato y aquellos que recibieron los otros sedantes. Conclusiones: El riesgo de hipotensión posterior a la secuencia de intubación rápida con etomidato no presenta diferencias significativas comparado con otros sedantes. Sin embargo, hay heterogeneidad en los estudios incluidos.(AU)

Introduction: Rapid sequence intubation is an airway rescue and protection technique in which different sedatives are used to perform orotracheal intubation. Etomidate, due to its pharmacokinetic and pharmacodynamic qualities, particularly hemodynamic stability, is the most widely used sedative in this scenario. However, its superiority over other sedatives is controversial. Materials and methods: We performed a meta-analysis using a pre-designed protocol and PRISMA guidelines to evaluate the mean difference between systolic blood pressure before and after administration of the sedative. We also analyzed the relative risks of hypotension. Results: Ten studies were included. The incidence of hypotension in patients receiving etomidate ranged from 6.4% to 75.2%, and between 24.0% and 65.9% in patients receiving other sedatives. No significant differences were found in the mean difference in systolic blood pressure during pre-intubation 0.01mmHg (95% CI: –0.90; 0.92) or in post-intubation 0.98mmHg (95% CI: –0.24; 2.20). The relative risk analysis showed that the risk of hypotension is equal to an RR of 1.19 (95% CI: 0.92-1.54) between those who received etomidate and those who received the other sedatives. Conclusions: The risk of hypotension after rapid intubation sequence with etomidate does not differ significantly compared to other sedatives. However, the studies included in this review were heterogeneous.(AU)

A systematic review and meta-analysis of the hemodynamic effects of etomidate versus other sedatives in patients undergoing rapid sequence intubation.

INTRODUCTION: Rapid sequence intubation is an airway rescue and protection technique in which different sedatives are used to perform orotracheal intubation. Etomidate, due to its pharmacokinetic and pharmacodynamic qualities, particularly hemodynamic stability, is the most widely used sedative in this scenario. However, its superiority over other sedatives is controversial. MATERIALS AND METHODS: We performed a meta-analysis using a pre-designed protocol and PRISMA guidelines to evaluate the mean difference between systolic blood pressure before and after administration of the sedative. We also analyzed the relative risks of hypotension. RESULTS: Ten studies were included. The incidence of hypotension in patients receiving etomidate ranged from 6.4% to 75.2%, and between 24.0% and 65.9% in patients receiving other sedatives. No significant differences were found in the mean difference in systolic blood pressure during pre-intubation 0.01 mm Hg (95% CI: -0.90; 0.92) or in post-intubation 0.98 mmHg (95% CI: -0.24; 2.20). The relative risk analysis showed that the risk of hypotension is equal to an RR of 1.19 (95% CI: 0.92-1.54) between those who received etomidate and those who received the other sedatives. CONCLUSIONS: The risk of hypotension after rapid intubation sequence with etomidate does not differ significantly compared to other sedatives. However, the studies included in this review were heterogeneous.

TCNQ molecular semiconductor of the Cu(II)TAAB macrocycle: Optical and electrical properties.

The present study reports the doping of a semiconducting molecular material through the formation of hydrogen bonds between the macrocycle Cu(II)(TAAB) and the electronic acceptor TCNQ. According to density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) analysis, the doped compound has the shape of a distorted square pyramid, with four nitrogen atoms in the equatorial position and the apical oxygen atom from the water ligands. These water molecules can generate strong hydrogen bonds with TCNQ and the TAAB metallic complex. Thin films of copper molecular material were obtained through high vacuum evaporation and were structurally characterized by IR spectroscopy, EPR and scanning electron microscopy (SEM). Additionally, the absorption coefficient (α) and photon energy (hν) were calculated from UV-vis spectroscopy and used to determine the optical activation energy in each film, from which its semiconducting behavior was established. An important aspect to consider is that the presence of hydrogen bonds is essential to establish the semiconducting nature of these species; this chemical behavior, as well as the resulting electronic mobility, have been studied by DFT theoretical calculations, which reinforce the experimental conclusion of a relationship between Cu(II)TAAB and TCNQ moieties generated by a weak bond. Finally, I-V characteristics have been obtained from a glass/ITO/doped molecular semiconductor/Ag device using Ag and ITO electrodes. Results for the copper-based device show that, at low voltages, the conduction process is of an ohmic nature while, at higher voltages, space-charge-limited current (SCLC) is found. It is highly probable that the doping effect in TCNQ favors electronic transport due to the formation of conduction channels caused by dopant-favored anisotropy.

Electrical and optical properties of copper and nickel molecular materials with tetrabenzo [b,f,j,n] [1,5,9,13] tetraazacyclohexadecine thin films grown by the vacuum thermal evaporation technique.

Semiconducting molecular-material thin-films of tetrabenzo (b,f,j,n) [1,5,9,13] tetraazacyclohexadecine copper(II) and nickel(II) bisanthraflavates have been prepared by using vacuum thermal evaporation on Corning glass substrates and crystalline silicon wafers. The films thus obtained were characterized by infrared spectroscopy (FTIR), atomic force microscopy (AFM), ultraviolet-visible (UV-vis) spectroscopy and ellipsometry. IR spectroscopy showed that the molecular-material thin-films exhibit the same intra-molecular bonds as the original compounds, which suggests that the thermal evaporation process does not significantly alter their bonds. The optical band-gap values calculated from the absorption coefficient may be related to non-direct electronic interband transitions. The effect of temperature on conductivity was also measured in these samples. It was found that the temperature-dependent electric current is always higher for the nickel-based material and suggests a semiconductor-like behavior with conductivities in the order of 10(-8)Omega(-1)cm(-1).

Electrical and optical properties of C46H22N8O4KM (M=Co, Fe, Pb) molecular-material thin films prepared by the vacuum thermal evaporation technique.

In this work, the synthesis of new materials formed from metallic phthalocyanines (Pcs) and double potassium salt from 1,8-dihydroxianthraquinone is reported. The newly synthesized materials were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), infrared (IR) and Ultraviolet-visible (UV-vis) spectroscopy. The powder and thin-film samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds as in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The effect of temperature on conductivity and electrical conduction mechanism was measured in the thin films (approximately 137 nm thickness). They showed a semiconductor-like behaviour with an optical activation energy arising from indirect transitions of 2.15, 2.13 and 3.6eV for the C(46)H(22)N(8)O(4)KFe, C(46)H(22)N(8)O(4)KPb and C(46)H(22)N(8)O(4)KCo thin films.

Arterial pressure-flow relationship in patients undergoing cardiopulmonary bypass.

We determined the arterial pressure-flow relationship experimentally by means of step changes of blood flow in 30 adult patients undergoing cardiopulmonary bypass (CPB). Anesthesia technique was uniform. CPB was nonpulsatile; hypothermia to 25-28 degrees C, and hemodilution to 18%-25% hematocrit were used. During stable bypass, mean arterial pressure was recorded first with blood flow 2.2 L.min-1.m-2. Flow was then increased to 2.9 L.min-1.m-2 for 10 s and reverted to baseline for 1 min. Then it was decreased to 1.45 L.min-1.m-2 for 10 s, and reverted to baseline for 1 min. Subsequently, it was decreased to 0.73 L.min-1.m-2 for 10 s and then reverted to baseline. Similar sets of measurements were repeated after 0.25 mg of phenylephrine and once the patient was rewarmed. The pressure-flow function was individually determined by regression, and the critical pressure estimated by extrapolation to zero flow. All patients had zero-flow critical pressure during hypothermia, with a mean value of 21.8 +/- 6.4 mm Hg (range 8.8-38.9). It increased after 0.25 mg phenylephrine to 25.4 +/- 7.2 mm Hg (range 12.2-43.9, P < 0.001). During normothermia, critical pressure was 21.2 +/- 5 mm Hg (range 13.4-30.9), not significantly different from hypothermia. During hypothermia, the slope of the pressure-flow function (i.e., resistance) was 14.9 +/- 3.5 mm Hg.L-1.min-1.m-2 (range 7.6-22.1). It increased significantly (P < 0.001) after phenylephrine, to 19.7 +/- 6.2 mm Hg.L-1.min-1.m-2 (range 11.4-40.5), and returned to 15.4 +/- 3.4 mm Hg.L-1.min-1.m-2 (range 10.1-24.2) during normothermic bypass. Systemic vascular resistance appeared to vary reciprocally with blood flow, although this finding may represent a mathematical artifact, which can be avoided by using zero-flow critical pressure in the vascular resistance equation.