Browsing by Author "Cortinez Fernández, Luis Ignacio"

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    Differential effects of propofol anaesthesia across three amplitude-defined electroencephalographic states in sedated critically ill term neonates
    (European Society of Anaesthesiology and Intensive Care, 2025) Boncompte Lezaeta, Gonzalo Nicolas; Cortinez Fernández, Luis Ignacio; Toso Milos, Alberto Antonio; Giordano Villatoro, Ady Iveth; Cruzat Riquelme, Francisco Javier; Fuentes, Ricardo; Pedemonte Trewhela, Juan Cristóbal; Contreras Ibacache, Víctor Eliseo; Biggs Muñoz, Daniela Paola; Chiu, Esteban; Ibacache Figueroa, Mauricio Enrique
    The developing neonatal brain displays different electroencephalographic (EEG) responses to GABAergic anaesthetics than adults. Evidence suggests the importance of isoelectric-like activity patterns. However, markers of hypnotic depth are currently lacking for this population. OBJECTIVE To explore potential EEG markers of propofol-induced hypnosis in sedated critically ill term neonates. DESIGN Observational exploratory cohort study. PATIENTS Twenty critically ill term neonates (postmenstrual age 37 to 44 weeks) undergoing intensive care and requiring anaesthesia for noncardiac surgery. Patients with perinatal asphyxia, neurological pathology, brain malformations and metabolic or haemodynamic instability were excluded. INTERVENTION(S) Frontal EEG (Sedline) was recorded before induction and during a 20-min continuous rate propofol infusion. MAIN OUTCOME MEASURES Depending on peak amplitude, segmented EEG signals (1 s epochs) were classified as either isoelectric (<10 μV), low-voltage 10 to 25 μV), or high-voltage (>25 μV). Propofol effects were evaluated in terms of time occupancy and spectral properties within these EEG states. Correlations between clinical variables and EEG states were explored. RESULTS The EEGs of 17 neonates were analysed. Most showed periods of low-voltage (16/17, 94%) and isoelectric states (2/17, 70.5%) before anaesthesia. The time spent in these EEG states increased significantly during propofol infusion; 17/17 (100%), P < 0.001 and 16/17 (94.1%), P = 0.016, respectively. Propofol increased the mean [95% confidence interval (CI)] time spent in the isoelectric state per patient: 12.4 (3.3 to 21.5)% versus 28.6 (14.4 to 42.8)%, P < 0.002. A reduced spectral power was observed across all frequency bands during low-voltage states (all P < 0.026). Gestational age was negatively correlated with time in the isoelectric state; rho, 95% CI, −0.539 (−0.11 to −0.87), P = 0.031. CONCLUSION Our results show that isoelectric periods are common before anaesthesia in our studied population and more frequent in patients born at earlier gestational ages. The data suggest that propofol anaesthesia increases isoelectric EEG states while also reducing the spectral power, specifically during low-voltage EEG states. Potentially, both of these EEG changes could be biomarkers of neonatal hypnosis depth in this particular critically ill subpopulation. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT04904965.
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    Pharmacokinetic modelling and simulation for prolonged infusion of levobupivacaine with or without epinephrine in transversus abdominis plane and erector spinae plane blocks: a randomised controlled trial and analysis of pooled data
    (2025) Araneda, Andrea; De La Cuadra Fontaine, Juan Carlos; Corvetto Aqueveque, Marcia Antonia; Balde Sepúlveda, Detlef Peter Mario; De La Fuente Sanhueza, Rene Francisco; Ibacache Figueroa, Mauricio Enrique; Contreras, Víctor; Solari Gajardo, Sandra; Cortinez Fernández, Luis Ignacio
    Background: Interfacial blocks often require large volumes of local anaesthetic, raising concerns about systemic absorption and potential toxicity. This study examined the pharmacokinetics of levobupivacaine with and without epinephrine during thoracic erector spinae plane (ESP) or transversus abdominis plane (TAP) blocks, simulating reported 48-h dosing regimens to evaluate safety. Methods: Data from three studies were analysed. Study 1 included 38 patients receiving an ESP block before video-assisted thoracoscopy, whereas Study 2 analysed published data on TAP blocks. Both studies used 20 ml of levobupivacaine 0.25% with or without epinephrine (5 μg ml−1), measuring arterial concentrations over 90 min. Study 3 involved intravenous bupivacaine administration in 10 healthy volunteers. Pharmacokinetic analysis used NONMEM software, with significance set at P<0.05. Results: We analysed 258 ESP samples, 150 TAP samples, and 190 bupivacaine i.v. samples. A one-compartment model described the data, with a mean distribution volume of 41.9 L (coefficient of variation, 47%) and clearance rate of 0.288 L min−1 (coefficient of variation, 38%). Epinephrine reduced bioavailability (54.3% vs 32.8%) and prolonged absorption half-life (0.84 min vs 1.55 min; P<0.05). Simulated doses of 50 mg plus 300 mg per 24 h over 48 h remained below toxic thresholds. Conclusions: Similar dosing regimens for ESP and TAP blocks are supported by this pharmacokinetic analysis, with epinephrine effectively reducing systemic drug concentrations by prolonging absorption half-life and lowering bioavailability. The findings suggest that extended 300 mg per 24 h dosing for 48 h is likely to be safe. Further studies in broader patient populations are warranted to evaluate safety.
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    Propofol induce modulaciones espectrales diferenciales en los estados isoeléctricos en el EEG de neonatos
    (2023) Ibacache Figueroa, Mauricio Enrique; Boncompte Lezaeta, Gonzalo Nicolás; Cortinez Fernández, Luis Ignacio; Toso Milos, Alberto Antonio; Fuentes, Ricardo; Contreras Ibacache, Victor Eliseo; Biggs Muñoz, Daniela Paola; Chiu, Esteban