Changes in the heart rate variability in patients with obstructive sleep apnea and its response to acute CPAP treatment

Obstructive Sleep Apnea (OSA) is a major risk factor for cardiovascular disease. The goal of this study was to demonstrate whether the use of CPAP produces significant changes in the heart rate or in the heart rate variability of patients with OSA in the first night of treatment and whether gender and obesity play a role in these differences. METHODS: Single-center transversal study including patients with severe OSA corrected with CPAP. Only patients with total correction after CPAP were included. Patients underwent two sleep studies on consecutive nights: the first night a basal study, and the second with CPAP. We also analyzed the heart rate changes and their relationship with CPAP treatment, sleep stages, sex and body mass index. Twenty-minute segments of the ECG were selected from the sleep periods of REM, no-REM and awake. Heart rate (HR) and heart rate variability (HRV) were studied by comparing the R-R interval in the different conditions. We also compared samples from the basal study and CPAP nights. RESULTS: 39 patients (15 females, 24 males) were studied. The mean age was 50.67 years old, the mean AHI was 48.54, and mean body mass index was 33.41 kg/m(2) (31.83 males, 35.95 females). Our results showed that HRV (SDNN) decreased after the use of CPAP during the first night of treatment, especially in non-REM sleep. Gender and obesity did not have any influence on our results. CONCLUSIONS: These findings support that cardiac variability improves as an acute effect, independently of gender or weight, in the first night of CPAP use in severe OSA patients, supporting the idea of continuous use and emphasizing that noncompliance of CPAP treatment should be avoided even if it is just once

Brain death: Is it an appropriate term?

Introduction: Brain death is generally accepted as a concept to indicate death. It was introduced about 40 years ago, and it was considered the ideal situation for donation of organs. Material and methods: During this time, however, there have been problems in the understanding of this concept both in the medical profession and in the general population. University students from medical and non-medical schools were tested for their understanding of this concept. Results: Our results show that less than one third of the non-medical students identified brain death as death. The data from the medical students changed as they progressed through their studies, but only 2/3 of the graduating medical class believed that brain death is death. Conclusion: Similar results have been seen in other universities around the world, and a renewed effort on the re-education of the concept of brain death may be worthwhile. Although we cannot extrapolate these results to the general population, the confusion is probably similar; hence an effort should be made to solve this problem. Resumen: Objetivo: “Muerte cerebral” es un término generalmente aceptado para indicar la muerte. Fue introducido hace más de 40 años, y, desde entonces, se considera la situación ideal para la donación de órganos. Sin embargo, existen serios problemas con respecto a la comprensión de este concepto, tanto en profesionales médicos como en la población general. Métodos: Se realizó una encuesta a estudiantes universitarios de facultades médicas y no médicas para comprobar la interpretación del concepto de muerte cerebral. Resultados: Menos de un tercio de los estudiantes no médicos identificaron claramente muerte cerebral con muerte. Los datos en estudiantes de Medicina diferían a medida que los cursos eran más avanzados, pero sólo dos tercios de los alumnos de último curso de Medicina pensaban que la muerte cerebral equivalía a muerte. Resultados similares se han encontrado en universidades de otros países, siendo necesario un mayor esfuerzo en la docencia del concepto de muerte cerebral. Conclusiones: Los resultados de este trabajo muestran la confusión existente entre universitarios a la hora de interpretar el término “muerte cerebral”; aunque esta confusión no es extrapolable a la población general es probable que la confusión en la población no sea menor. Por ello, dada la importancia del tema, deberían plantearse soluciones para resolver esta confusión, bien explicando mejor el término o modificando la terminología. Keywords: Brain death, Misunderstanding, Palabras clave: Muerte cerebral, Malinterpretació

Muerte cerebral: ¿es un término adecuado?

Resumen: Objetivo: “Muerte cerebral” es un término generalmente aceptado para indicar la muerte. Fue introducido hace más de 40 años y, desde entonces, se considera la situación ideal para la donación de órganos. Sin embargo, existen serios problemas con respecto a la comprensión de este concepto, tanto en profesionales médicos como en la población general. Métodos: Se realizó una encuesta a estudiantes universitarios de facultades médicas y no médicas para comprobar la interpretación del concepto de muerte cerebral. Resultados: Menos de un tercio de los estudiantes no médicos identificaron claramente muerte cerebral con muerte. Los datos en estudiantes de Medicina diferían a medida que los cursos eran más avanzados, pero sólo dos tercios de los alumnos de último curso de Medicina pensaban que la muerte cerebral equivalía a muerte. Resultados similares se han encontrado en universidades de otros países, siendo necesario un mayor esfuerzo en la docencia del concepto de muerte cerebral. Conclusiones: Los resultados de este trabajo muestran la confusión existente entre universitarios a la hora de interpretar el término “muerte cerebral”; aunque esta confusión no es extrapolable a la población general es probable que la confusión en la población no sea menor. Por ello, dada la importancia del tema, deberían plantearse soluciones para resolver esta confusión, bien explicando mejor el término o modificando la terminología. Abstract: Introduction: Brain death is generally accepted as a concept to indicate death. It was introduced about 40 years ago, and it was considered the ideal situation for donation of organs. Methods: During this time, however, there have been problems in the understanding of this concept both in the medical profession and in the general population. University students from medical and non-medical schools were tested for their understanding of this concept. Results: Our results show that less than one third of the non-medical students identified brain death as death. The data from the medical students changed as they progressed through their studies, but only 2/3 of the graduating medical class believed that brain death is death. Conclusion: Similar results have been seen in other universities around the world, and a renewed effort on the re-education of the concept of brain death may be worthwhile. Although we cannot extrapolate these results to the general population, the confusion is probably similar; hence an effort should be made to solve this problem. Palabras clave: Muerte cerebral, Malinterpretación, Keywords: Brain death, Misunderstandin

Brain death: Is it an appropriate term?

Introduction: Brain death is generally accepted as a concept to indicate death. It was introduced about 40 years ago, and it was considered the ideal situation for donation of organs. Material and methods: During this time, however, there have been problems in the understanding of this concept both in the medical profession and in the general population. University students from medical and non-medical schools were tested for their understanding of this concept. Results: Our results show that less than one third of the non-medical students identified brain death as death. The data from the medical students changed as they progressed through their studies, but only 2/3 of the graduating medical class believed that brain death is death. Conclusion: Similar results have been seen in other universities around the world, and a renewed effort on the re-education of the concept of brain death may be worthwhile. Although we cannot extrapolate these results to the general population, the confusion is probably similar; hence an effort should be made to solve this problem. Resumen: Objetivo: “Muerte cerebral” es un término generalmente aceptado para indicar la muerte. Fue introducido hace más de 40 años, y, desde entonces, se considera la situación ideal para la donación de órganos. Sin embargo, existen serios problemas con respecto a la comprensión de este concepto, tanto en profesionales médicos como en la población general. Métodos: Se realizó una encuesta a estudiantes universitarios de facultades médicas y no médicas para comprobar la interpretación del concepto de muerte cerebral. Resultados: Menos de un tercio de los estudiantes no médicos identificaron claramente muerte cerebral con muerte. Los datos en estudiantes de Medicina diferían a medida que los cursos eran más avanzados, pero sólo dos tercios de los alumnos de último curso de Medicina pensaban que la muerte cerebral equivalía a muerte. Resultados similares se han encontrado en universidades de otros países, siendo necesario un mayor esfuerzo en la docencia del concepto de muerte cerebral. Conclusiones: Los resultados de este trabajo muestran la confusión existente entre universitarios a la hora de interpretar el término “muerte cerebral”; aunque esta confusión no es extrapolable a la población general es probable que la confusión en la población no sea menor. Por ello, dada la importancia del tema, deberían plantearse soluciones para resolver esta confusión, bien explicando mejor el término o modificando la terminología. Keywords: Brain death, Misunderstanding, Palabras clave: Muerte cerebral, Malinterpretació

Changes in the heart rate variability in patients with obstructive sleep apnea and its response to acute CPAP treatment

Obstructive Sleep Apnea (OSA) is a major risk factor for cardiovascular disease. The goal of this study was to demonstrate whether the use of CPAP produces significant changes in the heart rate or in the heart rate variability of patients with OSA in the first night of treatment and whether gender and obesity play a role in these differences. METHODS: Single-center transversal study including patients with severe OSA corrected with CPAP. Only patients with total correction after CPAP were included. Patients underwent two sleep studies on consecutive nights: the first night a basal study, and the second with CPAP. We also analyzed the heart rate changes and their relationship with CPAP treatment, sleep stages, sex and body mass index. Twenty-minute segments of the ECG were selected from the sleep periods of REM, no-REM and awake. Heart rate (HR) and heart rate variability (HRV) were studied by comparing the R-R interval in the different conditions. We also compared samples from the basal study and CPAP nights. RESULTS: 39 patients (15 females, 24 males) were studied. The mean age was 50.67 years old, the mean AHI was 48.54, and mean body mass index was 33.41 kg/m(2) (31.83 males, 35.95 females). Our results showed that HRV (SDNN) decreased after the use of CPAP during the first night of treatment, especially in non-REM sleep. Gender and obesity did not have any influence on our results. CONCLUSIONS: These findings support that cardiac variability improves as an acute effect, independently of gender or weight, in the first night of CPAP use in severe OSA patients, supporting the idea of continuous use and emphasizing that noncompliance of CPAP treatment should be avoided even if it is just once

Heart Rate Responses to Autonomic Challenges in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is accompanied by structural alterations and dysfunction in central autonomic regulatory regions, which may impair dynamic and static cardiovascular regulation, and contribute to other syndrome pathologies. Characterizing cardiovascular responses to autonomic challenges may provide insights into central nervous system impairments, including contributions by sex, since structural alterations are enhanced in OSA females over males. The objective was to assess heart rate responses in OSA versus healthy control subjects to autonomic challenges, and, separately, characterize female and male patterns. We studied 94 subjects, including 37 newly-diagnosed, untreated OSA patients (6 female, age mean±std: 52.1±8.1 years; 31 male aged 54.3±8.4 years), and 57 healthy control subjects (20 female, 50.5±8.1 years; 37 male, 45.6±9.2 years). We measured instantaneous heart rate with pulse oximetry during cold pressor, hand grip, and Valsalva maneuver challenges. All challenges elicited significant heart rate differences between OSA and control groups during and after challenges (repeated measures ANOVA, p<0.05). In post-hoc analyses, OSA females showed greater impairments than OSA males, which included: for cold pressor, lower initial increase (OSA vs. control: 9.5 vs. 7.3 bpm in females, 7.6 vs. 3.7 bpm in males), OSA delay to initial peak (2.5 s females/0.9 s males), slower mid-challenge rate-of-increase (OSA vs. control: −0.11 vs. 0.09 bpm/s in females, 0.03 vs. 0.06 bpm/s in males); for hand grip, lower initial peak (OSA vs. control: 2.6 vs. 4.6 bpm in females, 5.3 vs. 6.0 bpm in males); for Valsalva maneuver, lower Valsalva ratio (OSA vs. control: 1.14 vs. 1.30 in females, 1.29 vs. 1.34 in males), and OSA delay during phase II (0.68 s females/1.31 s males). Heart rate responses showed lower amplitude, delayed onset, and slower rate changes in OSA patients over healthy controls, and impairments may be more pronounced in females. The dysfunctions may reflect central injury in the syndrome, and suggest autonomic deficiencies that may contribute to further tissue and functional pathologies