A medical device is an instrument that includes components,parts,or accessories to diagnose or treat patients.Since the complexity of medical devices has increased in recent years,functional safety and basic safety ar...A medical device is an instrument that includes components,parts,or accessories to diagnose or treat patients.Since the complexity of medical devices has increased in recent years,functional safety and basic safety are required to ensure the overall device safety.Functional safety is part of the overall safety that relates to the equipment under control(EUC)and to the EUC control system that depends on the correct functionality of the electrical/electronic/programmable electronic(E/E/PE)safety-related systems.This study proposes approach methods to functional safety of medical devices for which it is important to correctly identify the safety functions and the safety integrity level(SIL).The relationship between the functional safety and essential performance is identified focusing on the safety function.The essential performance of E/E/PE systems is defined as the safety function of the functional safety.The target SIL of the essential performance is determined according to the potential risk levels,based on the classification rules of medical devices.This approach is applied to the pulse oximeter as a case study.The target SIL for the functionality of the power-failure alarm condition is determined to be SIL1.The target SILs of other functions are determined as SIL2.展开更多
The effects of perindopril and metoprolol on left ventricular hypertrophy (LVH) and function were studied in 47 essential hypertensive patients with LVH. Previous antihypertensive drugs were discontinued for at least ...The effects of perindopril and metoprolol on left ventricular hypertrophy (LVH) and function were studied in 47 essential hypertensive patients with LVH. Previous antihypertensive drugs were discontinued for at least 2 weeks, after which patients were randomly divided into 2 groups. 25 subjects were treated with perindopril 4 to 8 mg once daily in the morning (Group A) and 22 subjects with metoprolol 25 to 62.5 mg twice daily (Group B). The subjects were evaluated before and after 4 and 8 weeks of treatment by use of echocardiography. Before treatment LV mass indexes (LVMI) of two groups were respectively 143.2 ± 21.3 g / m2 and 140.6 ± 23.7 g / m2 (P>0.05). In Group A, reduction of LVMI occurred after 4 weeks of treatment, and more pronounced after 8 weeks (from 143.2 ± 21.3 g / m2 to 126.6 ± 15.3 g / m2, P< 0.001), whereas reduction of LVMI occurred only after 8 weeks in Group B (from 140.6 ± 23.7 g / m2 to 133.4 ± 13.2 g / m2, P< 0.001). In addition, there was a significant (P<0.05) difference in LVMI between the two groups after 8 weeks. LV systolic function remained unchanged, whereas E / A increased significantly (P< 0.001) in two groups after 8 weeks. In conclusion, antihypertensive treatment with perindopril and metoprolol induced a significant regression of LVH associated with improvement in LV diastolic performance. Perindopril, compared with metoprolol, was more effective in reversing LVH.展开更多
文摘A medical device is an instrument that includes components,parts,or accessories to diagnose or treat patients.Since the complexity of medical devices has increased in recent years,functional safety and basic safety are required to ensure the overall device safety.Functional safety is part of the overall safety that relates to the equipment under control(EUC)and to the EUC control system that depends on the correct functionality of the electrical/electronic/programmable electronic(E/E/PE)safety-related systems.This study proposes approach methods to functional safety of medical devices for which it is important to correctly identify the safety functions and the safety integrity level(SIL).The relationship between the functional safety and essential performance is identified focusing on the safety function.The essential performance of E/E/PE systems is defined as the safety function of the functional safety.The target SIL of the essential performance is determined according to the potential risk levels,based on the classification rules of medical devices.This approach is applied to the pulse oximeter as a case study.The target SIL for the functionality of the power-failure alarm condition is determined to be SIL1.The target SILs of other functions are determined as SIL2.
文摘The effects of perindopril and metoprolol on left ventricular hypertrophy (LVH) and function were studied in 47 essential hypertensive patients with LVH. Previous antihypertensive drugs were discontinued for at least 2 weeks, after which patients were randomly divided into 2 groups. 25 subjects were treated with perindopril 4 to 8 mg once daily in the morning (Group A) and 22 subjects with metoprolol 25 to 62.5 mg twice daily (Group B). The subjects were evaluated before and after 4 and 8 weeks of treatment by use of echocardiography. Before treatment LV mass indexes (LVMI) of two groups were respectively 143.2 ± 21.3 g / m2 and 140.6 ± 23.7 g / m2 (P>0.05). In Group A, reduction of LVMI occurred after 4 weeks of treatment, and more pronounced after 8 weeks (from 143.2 ± 21.3 g / m2 to 126.6 ± 15.3 g / m2, P< 0.001), whereas reduction of LVMI occurred only after 8 weeks in Group B (from 140.6 ± 23.7 g / m2 to 133.4 ± 13.2 g / m2, P< 0.001). In addition, there was a significant (P<0.05) difference in LVMI between the two groups after 8 weeks. LV systolic function remained unchanged, whereas E / A increased significantly (P< 0.001) in two groups after 8 weeks. In conclusion, antihypertensive treatment with perindopril and metoprolol induced a significant regression of LVH associated with improvement in LV diastolic performance. Perindopril, compared with metoprolol, was more effective in reversing LVH.
