RESUMO
INTRODUCTION: Maintaining an appropriate level of cognitive load during simulations is crucial to optimize learning. We evaluated 3 subjective measures of cognitive load in a simulated operating room (OR) context across multiple scenarios of varying complexity. METHODS: This observational study of 25 first-year anesthesiology residents took place during a 5-day simulation "Boot Camp." Each day, participants completed 2 different high-fidelity scenarios in a fully equipped simulated OR. After each simulation, participants completed 3 cognitive load measures: the Paas scale, NASA Task Load Index (TLX), and Cognitive Load Component (CLC) questionnaire. Two-way repeated-measures and mixed-design analyses of variance, with the cognitive load measures and scenarios as independent factors, were used to determine the effect of using different measures to report cognitive load. RESULTS: Cognitive load scores reported by all measures correlated significantly with one another (P < 0.01): TLX and Paas (r = 0.65); Paas and CLC (r = 0.63); and TLX and CLC (r = 0.61). The CLC subscale scores (intrinsic, extraneous, germane) also correlated significantly with composite TLX and Paas scores (P < 0.01). Scenarios and measures displayed significant interaction: F(10, 210) = 3.01, P = 0.001. Participants reported highest overall cognitive load using the Paas scale. CONCLUSIONS: All cognitive load measures were sensitive to scenario variability and showed similar fluctuation patterns across the 10 scenarios. The findings suggest that cognitive load measures can help create benchmarks based on learner perceptions of cognitive burden for different simulation scenarios.
Assuntos
Anestesiologia/educação , Cognição , Treinamento por Simulação , Adulto , Simulação por Computador , Feminino , Humanos , Capacitação em Serviço , Internato e Residência , Masculino , Inquéritos e QuestionáriosRESUMO
PRIMARY OBJECTIVE: The objective of this study is to assess the functional state of the autonomic nervous system in healthy individuals and in individuals in coma using measures of heart rate variability (HRV) and to evaluate its efficiency in predicting mortality. DESIGN AND METHODS: Retrospective group comparison study of patients in coma classified into two subgroups, according to their Glasgow coma score, with a healthy control group. HRV indices were calculated from 7 min of artefact-free electrocardiograms using the Hilbert-Huang method in the spectral range 0.02-0.6 Hz. A special procedure was applied to avoid confounding factors. Stepwise multiple regression logistic analysis (SMLRA) and ROC analysis evaluated predictions. RESULTS: Progressive reduction of HRV was confirmed and was associated with deepening of coma and a mortality score model that included three spectral HRV indices of absolute power values of very low, low and very high frequency bands (0.4-0.6 Hz). The SMLRA model showed sensitivity of 95.65%, specificity of 95.83%, positive predictive value of 95.65%, and overall efficiency of 95.74%. CONCLUSIONS: HRV is a reliable method to assess the integrity of the neural control of the caudal brainstem centres on the hearts of patients in coma and to predict patient mortality.
Assuntos
Coma/diagnóstico , Coma/fisiopatologia , Eletrocardiografia/métodos , Escala de Coma de Glasgow , Frequência Cardíaca/fisiologia , Adulto , Idoso , Sistema Nervoso Autônomo/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
Key autonomic functions are in continuous development during adolescence which can be assessed using the heart rate variability (HRV). However, the influence of different demographic and physiological factors on HRV indices has not been fully explored in adolescents. In this study we aimed to assess the effect of age, gender, and heart rate on HRV indices in two age groups of healthy adolescents (age ranges, 13-16 and 17-20 years) and two groups of healthy young adults (21-24 and 25-30 years). We addressed the issue using 5-min ECG recordings performed in the sitting position in 255 male and female participants. Time, frequency, and informational domains of HRV were calculated. Changes in HRV indices were assessed using a multiple linear regression model to adjust for the effects of heart rate, age, and gender. We found that heart rate produced more significant effects on HRV indices than age or gender. There was a progressive reduction in HRV with increasing age. Sympathetic influence increased with age and parasympathetic influence progressively decreased with age. The influence of gender was manifest only in younger adolescents and young adults. In conclusion, age, gender, and particularly heart rate have a substantial influence on HRV indices, which ought to be considered to avoid biases in the study of the autonomic nervous system development. The lack of the gender-related effects on HRV indices in late adolescence could be related to non-completely achieved maturity of the autonomic mechanisms, which deserves further exploration.
Assuntos
Fatores Etários , Frequência Cardíaca , Fatores Sexuais , Adolescente , Adulto , Sistema Nervoso Autônomo , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Literature reports on the very high frequency (VHF) range of 0.4-0.9 Hz in heart rate variability (HRV) are scanty. The VHF presence in cardiac transplant patients and other conditions associated with reduced vagal influence on the heart encouraged us to explore this spectral band in healthy subjects and in patients diagnosed with cardiac autonomic neuropathy (CAN), and to assess the potential clinical value of some VHF indices. The study included 80 healthy controls and 48 patients with spinocerebellar ataxia type 2 (SCA2) with CAN. The electrocardiographic recordings of short 5-min duration were submitted to three different spectral analysis methods, including the most generally accepted procedure, and the two novel methods using the Hilbert-Huang transform. We demonstrated the presence of VHF activity in both groups of subjects. However, VHF power spectral density, expressed in relative normalized units, was significantly greater in the SCA2 patients than that in healthy subjects, amounting to 36.1 ± 17.4% vs. 22.9 ± 14.1%, respectively, as also was the instantaneous VHF spectral frequency, 0.58 ± 0.05 vs. 0.64 ± 0.07 Hz, respectively. These findings were related to the severity of CAN. We conclude that VHF activity of HRV is integral to the cardiovascular autonomic control.
Assuntos
Doenças do Sistema Nervoso Autônomo/fisiopatologia , Sistema Cardiovascular/fisiopatologia , Frequência Cardíaca/fisiologia , Adulto , Doenças do Sistema Nervoso Autônomo/etiologia , Eletrocardiografia/métodos , Feminino , Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Ataxias Espinocerebelares/complicações , Ataxias Espinocerebelares/fisiopatologia , Adulto JovemRESUMO
A patient assessed by heart rate variability (HRV) methodology, beginning just after the completion of brain death (BD) diagnosis, showed remaining very low frequency (VLF) waves for approximately 10â min. A time-varying spectral analysis showed that during the first 550â s, a significant power spectral density remained in the high-frequency (HF), low-frequency (LF) and VLF bands. From 550 to 675â s, the HF oscillations totally vanished, and a marked progressive decay of the LF and VLF power density occurred. After 700 s the VLF undulations stopped and remaining small amplitude oscillations at 0.2 Hz coincided with the ventilator frequency. The VLF oscillations recorded in our case might be related to residual sympathetic vasomotor activity that progressively disappeared due to the extension of necrosis affecting the nervous centres of the lower part of the medulla and the first 2-3 cervical spine segments.