经颅多普勒超声检测脑血管反应性的应用价值

【摘要】 目的 探讨经颅多普勒超声检测脑血管反应性的应用价值。方法 选择2013年2月~2016年4月住院的颈动脉狭窄患者78例作为观察组,选择同期非颈动脉狭窄患者78例作为对照组,所有患者均进行经颅多普勒超声检查,连续监测大脑中动脉的脑血流速度变化,计算血管运动反应性(VMR)、脑血管运动储备(CRC)、呼吸抑制指数(BHI)等指标并进行相关性分析。结果 两组的性别、年龄、体重指数、血糖、收缩压、舒张压、总胆固醇、甘油三酯含量等对比差异无统计学意义(P＞0.05);观察组的超声Vm、Vs与Vd值明显低于对照组,而PI与RI值明显高于对照组,对比差异有统计学意义(P＜0.05);观察组的CRC、BHI与VMR值分别为9.35±1.62、0.42±0.21和0.18±0.14,都明显低于对照组的12.49±3.10、0.79±0.14和0.35±0.11(P＜0.05);直线相关性分析显示观察组的脑血管反应性指标CRC、BHI、VMR与常规超声指标Vm、Vs、Vd呈正相关性(P＜0.05),而PI、RI呈负相关性(P＜0.05)。结论 经颅多普勒超声监测脑血管反应性具有动态、简便的优势,可为临床发现脑灌注异常患者提供依据,且脑血管反应性与超声血流状况有一定的相关性,有利于指导病情判断与预后评估,可在临床推广应用。     

Physiological stress responses in defensive individuals: Age and sex matter

The association between defensiveness and physiological responses to stress were evaluated in 81 healthy working men and 118 women, aged 20 to 64 years (M=41; SD=11.45). Participants underwent laboratory testing during which they were exposed to interpersonal stressors. Heart rate (HR), heart rate variability (HRV), blood pressure (BP), and salivary cortisol were measured. Defensiveness was evaluated using the Marlowe‐Crowne Social Desirability Scale. In women, higher defensiveness was associated with greater BP and HR reactivity to stress (p<.05). In older men, lower defensiveness was associated with increased systolic BP reactivity to stress (p<.02), delayed HRV recovery (p<.02), and greater salivary cortisol levels (p<.02). In conclusion, greater defensiveness was associated with increased reactivity to stress in women whereas in older men, lower defensiveness was associated with elevated cardiovascular, autonomic, and endocrine responses to stress.     

The effects of experimenter status and cardiovascular reactivity on pain reports

Existing evidence suggests that experimenter characteristics can influence research participants' pain reports. To examine the possibility that cardiovascular reactivity may serve as a potential mediating mechanism, blood pressure responses to stress were recorded in 117 healthy women during an arithmetic task and a subsequent cold pressor pain task. Laboratory sessions were conducted by two experimenters (i.e., a university professor and a graduate research assistant), who differed significantly on participant ratings of perceived social status. Participants tested by the university professor showed greater blood pressure responsivity to arithmetic and had higher pain tolerance and lower pain unpleasantness ratings compared to those tested by the research assistant. Further, hierarchical regression analyses indicated that blood pressure reactivity was a potential mediator of the association between experimenter status and both pain tolerance and unpleasantness, suggesting that perceived experimenter status may elicit physiological adaptations that can reduce sensitivity to painful laboratory stimuli.     

Blood pressure and muscle sympathetic nerve activity during cold pressor stress: fitness and gender

We examined putative autonomic and hemodynamic mechanisms that might explain our prior finding that cardiorespiratory fitness mitigates blood pressure responses by normotensive women during the hand cold pressor test. We report that fitness level was inversely related to increases in systolic and diastolic blood pressures and muscle sympathetic nerve activity (MSNA) during the cold pressor among women but not men. The pattern of responses among fitter women was consistent with decreased central sympathetic outflow resulting in reduced stroke volume or dampened peripheral resistance in vascular beds other than calf skeletal muscle. Fitter men and women had slightly larger increases in blood pressure during mental arithmetic, but otherwise fitness was not directly related to stress responses. The results further encourage consideration of cardiorespiratory fitness as a modifying covariate when the hand cold pressor test is used as a predictor of future hypertension among women.     

Comparison of factors affecting platelet reactivity in various platelet function tests

Previous studies have reported that various factors affect ADP-induced platelet reactivity during clopidogrel therapy. The aim of this study was to determine whether clinical and laboratory variables for platelet reactivity during dual antiplatelet therapy (DAPT) are dependent on the assay used. We enrolled 904 patients receiving DAPT following coronary intervention. Platelet reactivity was measured using three methods: the VerifyNow P2Y12 assay, multiple electrode aggregometry (MEA) ADP assay, and the light transmittance aggregometry (LTA) ADP assay at 24–48 h following coronary intervention. The VerifyNow results demonstrated a significant inverse correlation with hematocrit value (r = –0.268, p < 0.0001); however, MEA results had no such correlation with hematocrit (r = 0.044, p = 0.188). There was a positive correlation between the MEA results and platelet count (r = 0.255, p < 0.0001). LTA was weakly influenced by hematocrit (r = –0.064, p = 0.057) and platelet count (r = 0.069, p = 0.040). Gender (odds ratio 1.53, 95% CI 1.10–2.14, p = 0.013) and hematocrit (odds ratio 0.91,95% CI 0.88–0.94, p < 0.0001) were the independent variables for HPR by VerifyNow. Smoking (odds ratio 0.38, 95% CI 0.16–0.94, p = 0.036) and platelet count (odds ratio 1.01, 95% CI 1.00–1.01, p < 0.0001) were independent factors for HPR when using the MEA assay, whereas platelet count (odds ratio 1.00, 95% CI 1.00–1.01, p = 0.006) was identified as the only independent variable for HPR when using LTA. The incidence of HPR and the influencing variables involved are dependent on the platelet function test used.     

Parental history of hypertension and enhanced cardiovascular reactivity are associated with decreased pain ratings

Ischemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives.     

Social ties and cardiovascular function: An examination of relationship positivity and negativity during stress

The quality and quantity of one's relationships have been reliably linked to morbidity and mortality. More recently, studies have focused on links between relationships and cardiovascular reactivity as a physiological mechanism via the stress-buffering hypothesis. However, not all social relationships are consistently positive which points to the importance of a more comprehensive examination of relationship that includes negative qualities. In this study, we manipulated relationship positivity and negativity with an experimenter and examined its influence on cardiovascular reactivity. Results revealed that relationship positivity was associated with lower systolic blood pressure (SBP) reactivity for men and women. Relationship negativity, on the other hand, was related to less of an increase in diastolic blood pressure (DBP) reactivity in men. Internal analyses showed that perceptions of positivity and negativity interacted such that high positivity/high negativity perceptions (ambivalence) were related to the highest SBP reactivity. Results of this study suggest that the quality of one's relationships is an important moderator of cardiovascular reactivity during stress.