Bilateral continuous erector spinae plane block for cardiac surgery: case series / Bloqueo bilateral continúo del plano erector de la espina para cirugía cardiaca: serie de casos

Abstract Multimodal analgesia in cardiac surgery sternotomy includes bilateral continuous erector spinae plane block (BC-ESPB). However, the effectiveness of the local anesthetic regimens is still uncertain. The purpose of this study was to assess pain control achieved with a multimodal analgesia regimen including BC-ESPB at the level of T5 with PCA with a 0.125 % bupivacaine infusion and rescue boluses. This is a descriptive case series study which recruited 11 adult patients undergoing cardiac surgery through sternotomy in whom multimodal analgesia including BC-ESPB was used, between February and April 2021, at a fourth level institution. All patients reported pain according to the numeric rating scale (NRS) ≤ 3 both at rest and in motion, at extubation and then 4 and 12 hours after surgery. After 24 hours the pain was NRS ≤ 3 in 100 % of the patients at rest and in 63.6 % in motion. At 48 h 81 % of the patients reported pain NRS ≤ 3 at rest and in motion. At 72h all patients reported pain NRS ≤ 3 at rest and 82 % in motion. The average intraoperative use of fentanyl was 2.35 µg/kg and postoperative hydromorphone was 5.3, 4.1 and 3.3 mg at 24, 48 and 72 hours, respectively. Hence, bilateral ESP block in continuous infusion plus rescue boluses allows for proper control of acute intra and post-operative pain.

Resumen En cirugía cardiaca mediante esternotomía, la analgesia multimodal incluye el bloqueo bilateral continuo del plano erector de la espina (BBC-ESP). Sin embargo, existe incertidumbre sobre la efectividad de los esquemas de dosificación del anestésico local. Se busca evaluar el control del dolor proporcionado por un esquema de analgesia multimodal que incluye el BBC-ESP a la altura de T5 con ACP de bupivacaína 0,125 % en infusión y bolos de rescate. Se trata de un estudio descriptivo, serie de casos. Se reclutaron 11 pacientes adultos sometidos a cirugía cardiaca mediante esternotomía en quienes se usó analgesia multimodal que incluía BBC-ESP entre febrero y abril del 2021, en una institución de cuarto nivel. Todos los pacientes refirieron dolor, según la escala numérica (EN) ≤ 3 tanto en reposo como en movimiento, a la extubación, a las 4 y a las 12 horas. A las 24 horas el dolor fue EN ≤ 3 en el 100 % de los pacientes en reposo y en el 63,6 % en movimiento. A las 48 h el 81 % de los pacientes refirieron dolor EN ≤ 3 en reposo y en movimiento. A las 72 h todos los pacientes presentaron dolor EN ≤ 3 en reposo y 82 % en movimiento. El consumo intraoperatorio promedio de fentanilo fue de 2,35 ug/kg y de hidromorfona posoperatoria de 5,3, 4,1 y 3,3 mg a las 24, 48 y 72 horas. Así, el BBC-ESP en infusión continua más bolos de rescate permiten el control del dolor agudo intra y posoperatorio.

Impacto del uso de analgesia peridural controlada por la paciente en la disminución del dolor durante el trabajo de parto en un hospital del suroccidente colombiano / Impact of the use of patient-controlled epidural analgesia on pain reduction during labor in a hospital in southwestern colombia

Introducción: La analgesia epidural controlada por la paciente (PCA) provee flexibilidad al permitir acomodar la analgesia de acuerdo con las necesidades crecientes del dolor a medida que progresa el trabajo de parto (TP). El propósito de este estudio es objetivar el impacto en el alivio del dolor y satisfacción materna en pacientes en TP con analgesia PCA.Pacientes y métodos: Estudio descriptivo prospectivo realizado en el segundo semestre del 2020. Se incluyeron gestantes con embarazo único con escala verbal numérica (EVN) mayor a 3 y se excluyeron a las pacientes con contraindicaciones para inserción de catéter. Posterior a la inserción, se valoró el dolor y se entregó un cuestionario para calificar el dolor a los 15 min y en el expulsivo.Resultados: La población estaba constituida por mujeres jóvenes, el 72 % con embarazo a término. El catéter peridural se insertó en la fase latente del trabajo de parto en el 53,4 % de los casos. Al momento de la inserción del catéter, la mediana de dolor fue de 8 (6-10), a los 15 minutos 2 (0-4) y en el expulsivo 5 (3-8). El 75 % de las maternas refirieron estar muy satisfechas y el 19 % satisfechas; un 3 % indicaron estar poco satisfechas y el 1 % restante, insatisfechas. La prevalencia náusea y vómito fue del 16 % y 15 %, respectivamente.Conclusiones: PCA como estrategia analgésica durante el trabajo de parto a través de bolos intermitentes a demanda logró un adecuado control del dolor en los primeros minutos posterior a la inserción sin un control óptimo durante el expulsivo, sin embargo, se obtuvo una satisfacción materna global alta.(AU)

Introduction: Patient-controlled analgesia (PCA) allows patients to accommodate analgesia according to increasing pain needs as labor progresses. This study aims to objectify the impact on pain relief and maternal satisfaction in labor patients with PCA analgesia.Patients and methods: A prospective descriptive study was carried out in the second semester of 2020. Pregnant women with a singleton pregnancy with a numerical rating scale (NRS) greater than three were included, and patients with contraindications for catheter insertion were excluded. After insertion, pain was assessed, and a questionnaire was given to rate pain at 15 min and during expulsion.Results: The population consisted of young women, 72 % of whom were pregnant at term. The epidural catheter was inserted in the latent phase of labor in 53.4 % of cases. At the time of catheter insertion, the median pain was 8 (6-10), at 15 minutes 2 (0-4), and expulsion 5 (3-8). Seventy-five percent of the mothers reported being very satisfied and 19 % satisfied; 3 % reported being slightly satisfied, and the remaining 1 % dissatisfied. The prevalence of nausea and vomiting was 16 % and 15 %, respectively.Conclusions: PCA as an analgesic strategy during labor through intermittent boluses on-demand achieved adequate pain control in the first minutes after insertion without optimal control during expulsion. However, high overall maternal satisfaction was obtained.(AU)

Phase sensitive low-coherence interferometry using microwave photonics.

We report on a low-coherence interferometer based on Microwave Photonics (MWP) which allows, for the first time to the best of our knowledge, stable determination of the interferogram's phase. The interferometer is built on suppressed carrier, double-sideband modulation, dispersive propagation in a chirped fiber Bragg grating, demodulation by electro-optical frequency down-conversion, and suitable signal processing techniques to account for modulation impairments. Taking as a reference a direct normalization of the link's microwave response, the system retrieves high-resolution interferograms, both in amplitude and phase and free from distortion induced by higher-order dispersion, in an optical path difference of 16.3 mm, surpassing previously reported values based on MWP implementations. We present representative applications targeted to the characterization of C-band sources and components, such as direct analysis of interferograms with 5.5 fs temporal resolution, Fourier-transform spectroscopy with 14 GHz spectral resolution, and optical low-coherence reflectrometry of the impulse response's amplitude of fiber Bragg gratings with 0.55 µm spatial resolution.

Far-field Talbot waveforms generated by acousto-optic frequency shifting loops.

We report on the description of the optical fields generated by acousto-optic Frequency-Shifting Loops (FSL) in the temporal Fraunhofer domain when the loop is operated in the vicinity of integer or fractional Talbot conditions. Using self-heterodyne detection, we experimentally demonstrate the equivalence of the Talbot phases generated at fractional conditions with the Gauss perfect phase sequences, and identify deviations from the standard frequency-to-time mapping description of the far field. In particular, we show the existence of ripples in the pulse intensity, of unavoidable pulse-to-pulse interference in the pulse train, of small oscillations, of the order of hundreds of MHz, in the expected linear pulse chirp, and the capture of the phase at the pulse's trailing edge by the adjacent pulse. Using asymptotic analysis, we construct a field model that accounts for these features, which are due to corrections to the frequency-to-time mapped field created by the sharp spectral edge of the FSL spectrum, in analogy to diffraction. Practical design consequences for signal generation and processing systems based on FSL are discussed.

Laser ranging using coherent pulse compression with frequency shifting loops.

We report on the use of the acousto-optic frequency combs generated by frequency shifting loops as compact and versatile optical waveforms generators for pulse compression systems in the optical coherent domain. The high degree of tunability and mutual coherence of these sources permits an efficient use of the available detection bandwidth, and represent simple alternatives to broadband lasers that do not require fast electronics. The full, complex optical field is retrieved using heterodyne measurements in bandwidths as high as 20 GHz. Compression ratios up to 150 at 80-MHz repetition rate, with autocorrelation peak-to-sidelobe ratios in excess of 28 dB, are demonstrated. In a proof-of-concept ranging experiment, we obtain resolutions of 4 mm in free space at meter scales, limited by detection bandwidth. Systems based on frequency shifting loops thus enable compact implementations of the pulse compression concept in the optical coherent domain, for its use in general optical metrology systems.

Incoherent Optical Frequency-Domain Reflectometry Based on Homodyne Electro-Optic Downconversion for Fiber-Optic Sensor Interrogation.

Fiber-optics sensors using interrogation based on incoherent optical frequency-domain reflectometry (I-OFDR) offer benefits such as the high stability of interference in the radio-frequency (RF) domain and the high SNR due to narrowband RF detection. One of the main impairments of the technique, however, is the necessity of high-frequency detectors and vector network analyzers (VNA) in systems requiring high resolution. In this paper, we report on two C-band implementations of an I-OFDR architecture based on homodyne electro-optic downconversion enabling detection without VNA and using only low-bandwidth, high-sensitivity receivers, therefore alleviating the requirements of conventional I-OFDR approaches. The systems are based on a pair of modulators that are synchronized to perform modulation and homodyne downconversion at a reference frequency of 25.5 kHz. In the first system, we attain centimeter resolution with a sensitivity down to -90 dB using the modulation frequency range comprised between 3.2 and 14.2 GHz. In the second, we measured, for the first time using this approach, Rayleigh backscattering traces in standard single mode fiber with resolution of 6 m and a sensitivity of -83 dB by use of the 10.1-30.1 MHz range. These results show the feasibility of these simple, homodyne downconversion I-OFDR systems as compact interrogators for distributed or quasi-distributed optical fiber sensors.

Remote picometer fiber Bragg grating demodulation using a dual-wavelength source.

We report on the self-referenced, intensity-based, remote and passive interrogation of a fiber Bragg grating (FBG) for point sensing, by use of a reconfigurable dual-wavelength source composed of a tunable wavelength and subsequent suppressed-carrier, electro-optic amplitude modulation. The demodulation procedure is based on the measurement of the reflected power at two different wavelengths within the FBG spectral response. The grating was interrogated by use of conventional spectral analysis, and also after 32.9 km of single-mode fiber using a dispersive incoherent optical Fourier-domain reflectometry technique. Both procedures provide picometer resolution in the determination of Bragg wavelength shifts at a comparatively similar scan time (∼1 s) and received power (-16 dBm). The main limitations in each interrogation scheme have been identified. These results show the feasibility of interrogation systems incorporating relatively simple frequency combs at a calibrated, and eventually reconfigurable, wavelength grid with an, at least, similar performance to that of commercial FBG interrogators.