Browsing by Author "Contreras Ibacache, Víctor"

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    Pharmacokinetics of methadone in adult patients undergoing cardiac surgery with cardiopulmonary bypass
    (2024) Salas, Wilbaldo E.; Cortinez, Luis Ignacio; López Barreda, Rodrigo; Rolle, Augusto; Elgueta, Francisca; Godoy, César; Giordano Villatoro, Ady; Contreras Ibacache, Víctor; Anderson, Brian J.
    Cardiopulmonary bypass (CPB) induces profound physiological changes that may alter the pharmacokinetics of methadone. We aimed to describe the pharmacokinetics of an intravenous bolus of methadone racemate in adult patients undergoing heart surgery with CPB. METHODS: We prospectively studied 29 patients aged 45 to 75 years scheduled for cardiac surgery with CPB who received methadone 0.2 mg/kg after anesthesia induction. Arterial blood samples (n = 10) were taken, before, during, and after CPB. Pharmacokinetic analysis was undertaken using nonlinear mixed effects models. RESULTS: All patients completed the study. The median [interquartile range] methadone concentrations decreased from 34.8 [23.9–48.2] ng/mL (10 minutes before CPB) to 18.2 [9.9–26] ng/mL after 60 minutes of CPB (P < .001). A 3-compartment model adequately described the observed changes in methadone concentrations. The influence of CPB on methadone pharmacokinetics was best described by hemodilution in a fixed volume of 1.5 L (CPB circuit volume) and by sequestration from the CPB components (CLSEQ = 93.4 L/h, 95%CI 59–124, P < .01). The observed effect of CPB in methadone pharmacokinetics can be compensated by giving a supplementary bolus dose of 0.05 mg/kg at the end of CPB. CONCLUSIONS: Our results confirmed a decay in methadone concentrations during CPB, which, in our modeling analysis, was attributed to hemodilution and sequestration within the CPB components.
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    Prehabilitation for Chilean frail elderly people - pre-surgical conditioning protocol - to reduce the length of stay: randomized control trial
    (2024) Contreras Ibacache, Víctor; Elgueta Le-beuffe, María Francisca; Balde Sepulveda, Detlef Peter Mario; Astaburuaga Jorquera, Paula Daniela; Carrasco, Marcela; Pedemonte Trewhela, Juan Cristobal; Nicoletti Santoni, Maria Natalia; Medina Díaz, René; Figueroa, Constanza; Alamos Ramirez, Mirelly De Los Angeles; Cuzmar Benítez, Valeria; Vargas Moreno, Benjamin Ignacio; Barraza Mendizabal, Benjamin Juan Pablo; Retamal, Claudio; Cortinez Fernandez, Luis Ignacio; Franco, Sebastián; Agurto, Raul; Vivanco, Catherin
    Background: Frail elderly patients have a higher risk of postoperative morbidity and mortality. Prehabilitation is a potential intervention for optimizing postoperative outcomes in frail patients. We studied the impact of a prehabilitation program on length of stay (LOS) in frail elderly patients undergoing elective surgery.Methods: An RCT study was conducted. Frail patients scheduled for elective surgery were randomized to receive either pre-surgical conditioning protocol (PCP) or standard preoperative care. PCP included nursing, anesthetic, and geriatric assessment, nutritional intervention, and physical training for 4-weeks preoperatively. A nurse followed both groups until discharge criteria were met. The primary outcome was postoperative LOS. Secondary outcomes were nutritional status, preoperative frailty status (frailty phenotype-FP) after PCP, and postoperative complications up to three months categorized according to the Clavien-Dindo Classification. Means and medians between the control and intervention groups were compared, with statistical significance set at α=5%.Results: Thirty-four patients were to intervention and Thirty-seven to the control group. In the intervention group, adherence to prehabilitation was 90%. The median LOS after surgery was three days in both groups, without finding statistically significant differences between groups (P=0.754), although there was a trend towards lower LOS in the urologic surgery subgroup. We found a significant reduction in frailty status after PCP (FPpre=2.4±0.5 and FPpost=1.7±0.5, P<0.001). Nutritional status significantly improved in frail patients after prehabilitation (MNAbasal=9.0±2.5 and MNApost=10.6±2.6), P=0.028. The intervention group had less severe postoperative complications, which were not statistically significant.Conclusions: The PCP conducted both in-person and online, for older frail patients undergoing elective colorectal and urological surgery was not associated with shorter LOS. However, frailty status significantly improved after completing PCP.
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    Simulation-based training program for peripherally inserted central catheter placement. Randomized comparative study of in-person training with synchronous feedback versus distance training with asynchronous feedback
    (2024) Corvetto, Marcia A.; Kattan, Eduardo; Ramirez, Gaspar; Besa, Pablo; Abbott Cáceres, Eduardo Francisco; Zamorano Rivera, Elga del Carmen; Contreras Ibacache, Víctor; Altermatt, Fernando R.
    Simulation training that includes deliberate practice is effective for procedural skill training. Delivering feedback remotely and asynchronously has been examined for more cost-efficient training. This prospective randomized study aimed to compare 2 feedback techniques for simulation training: synchronous direct feedback versus asynchronous distance feedback (ASYNC). MethodsForty anesthesia and internal medicine residents were recruited after study approval by the institutional ethics committee. Residents reviewed instructional material on an online platform and performed a pretraining assessment (PRE) for peripherally inserted central catheter (PICC) placement. Each resident was then randomly assigned to 1 of 2 training types, practice with synchronous direct feedback (SYNC) or practice with ASYNC. Training consisted of four, 1-hour practice sessions; each was conducted once per week. Both groups underwent posttraining evaluation (POST). The PRE and POST assessments were videotaped and evaluated by 2 independent, blinded reviewers using a global rating scale. ResultsThirty-five residents completed the training program and both evaluations. Both groups had significantly improved global rating scale scores after 4 sessions. The SYNC group improved from 28 to 45 points (P < 0.01); the ASYNC group improved from 26.5 to 46 points (P < 0.01). We found no significant between-group differences for the PRE (P = 0.42) or POST assessments (P = 0.13). ConclusionThis simulation-based training program significantly improved residents' peripherally inserted central venous catheter placement skills using either modality. With these results, we are unable to demonstrate the superiority of synchronous feedback over ASYNC. Asynchronous feedback training modality represents a new, innovative approach for health care procedural skills training.
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    Validación modelos farmacocinéticos - farmacodinámicos de propofol en pacientes grandes quemados
    (2024) Ávila A., Marcela; Ulloa H., José; Serrano, Michael; Contreras Ibacache, Víctor; Cortínez, Luis Ignacio
    Los pacientes grandes quemados sufren grandes cambios fisiopatológicos. Existen 2 grandes fases: hipodinámica e hiperdinámica. La Anestesia total intravenosa, en modo target control infusión es una alternativa durante la fase hiperdinámica, pero, existe escasa evidencia de la capacidad de predicción de los modelos usados actualmente. Dada tal incertidumbre, se midió concentraciones plasmáticas de propofol en una cohorte de pacientes grandes quemados ingresados al Hospital de Urgencia Asistencia Pública y se comparó con las concentraciones predichas para los modelos Marsh y Schnider. Para la determinación de desempeño se calculó sesgo y error absoluto del modelo. Se evaluaron 112 mediciones de concentración plasmática pertenecientes a 11 pacientes. Para Schnider, el sesgo fue -8%, y el error global 48,7%. Para Marsh, el sesgo fue -13,5% y el error global 40,5%. Este estudio permite validar el uso del modelo Marsh en pacientes grandes quemados en fase hiperdinámica.