Heart Rate Variability and Hemodynamic Alterations in Canines with Normal Cardiac Function during Exposure to Pressure Support, Continuous Positive Airway Pressure, and a Combination of Pressure Support and Continuous Positive Airway Pressure
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Variations in intrathoracic pressure generated by different ventilator weaning modes may significantly affect intrathoracic hemodynamics and cardiovascular stability. Although several investigators have attributed cardiovascular alterations during ventilator weaning to augmented sympathetic tone, there is limited investigation of changes in autonomic tone during ventilator weaning. Heart rate variability (HRV), the analysis of beat-to-beat changes in heart rate, is a noninvasive indicator of autonomic tone that might be useful in the identification of patients who are at risk for weaning difficulty due to underlying cardiac dysfunction. The authors describe HRV and hemodynamics in response to 3 ventilatory conditions: pressure support (PS) 10 cmH2O, continuous positive airway pressure (CPAP) 10 cmH2O, and a combination of PS 10 cmH2O and CPAP 10 cmH2O (PS+CPAP) in a group of canines with normal ventricular function. Six canines were studied in the laboratory. Continuous 3-lead electrocardiographic data were collected during baseline (controlled mechanical ventilation) and following transition to each of the ventilatory conditions (PS, CPAP, PS+CPAP) for analysis of HRV. HRV was evaluated using power spectral analysis to define the power under the curve in a very low frequency range (0.0033 to < 0.04 Hz, sympathetic tone), a low frequency range (0.04 to < 0.15 Hz, primarily sympathetic tone), and a high frequency range (0.15 to < 0.40 Hz, parasympathetic tone). A thermodilution pulmonary artery catheter measured cardiac output and right ventricular end-diastolic volume to describe global hemodynamics. There were significant increases in very low frequency power (sympathetic tone) with a concomitant significant reduction in high-frequency power (parasympathetic tone) with exposure to PS+CPAP. These alterations in HRV were associated with significantly increased heart rate and reduced right ventricular end-diastolic volume. Although there was a small but significant increase in cardiac output with exposure to PS, HRV was unchanged. These data indicate that there was a relative shift in autonomic balance to increased sympathetic and decreased parasympathetic tone with exposure to PS+CPAP. The increase in intrathoracic pressure reduced right ventricular end-diastolic volume (preload). This hemodynamic alteration generated a change in autonomic tone, so that cardiac output could be maintained. Individuals with autonomic and/or cardiovascular dysfunction may not be capable of this type of response and may fail to successfully wean from mechanical ventilation.Circadian patterns of heart rate, systolic and diastolic blood pressure, and rate-pressure product were compared in elders with heart disease (N = 22, mean age 86 years) and a comparison group (N = 18, mean age 80 years) who did not have a cardiac diagnosis. For 4 consecutive days, automated measures of heart rate, diastolic and systolic blood pressure, and rate-pressure product were taken every 2 hours while subjects were awake. Activity-rest patterns were recorded by an observer, and demographic and medication profiles were obtained. Data were subjected to cosinor analysis, and the groups were compared on rhythmic parameters. Although the cardiac subjects were older, in poorer health, less active, and more prone to daytime napping, they exhibited more rhythms in rate-pressure product than did the comparison subjects. The cardiac group also had more synchronized oscillation of overt heart rate and systolic blood pressure rhythms. These results can be attributed to standardized times of cardiac medication administration. Attention to patterns of heart rate and systolic blood pressure in elders may suggest more appropriate times of day for conducting individual cardiac assessments.
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신경심장학의 발전으로 중추신경 활성이 심장의 전기적 활동도에 미치는 영향이 밝혀지고 있고, 심박동수변이(Heart rate variability, HRV)가 정신적 스트레스와 심혈관질환의 기계적 연관성을 나타내는 중요한 지표로 제기되고 있다. HRV란 자율신경계의 정상적 상호작용에 의해 나타나는 생리적인 심박수 변동을 타나내며, 자율신경 기능을 정량화하여 측정할 수 있는 방법론이다. 분석 방법은 시간 영역 분석과 주파수 영역 분석으로 나눌 수 있으며, 측정 시간대에 따라 단기간 측정과 24시간 측정 등의 방법이 확립되어 있다. 임상적으로는 변이 정도, 교감신경과 부교감신경의 활성과 균형도를 파악하여 다양한 질환과 스트레스 등의 진단과 치료 및 예후 판정에 활용되고 있다. HRV를 이용한 바이오피드백도 최근 자율신경 관련 질환의 치료에 활용되고 있다. 향후 다양한 프로토콜의 개발과 임상적 적용이 필요할 것으로 보인다. 【In this article, the effects of stress on central nerve system and heart function and the concept of heart rate variability were reviewed. HRV(Heart Rate Variability), the periodical change of the heart rate, is indicated larger in the healthier because they respond flexibly to various sorts of facts influencing on HR. HRV analysis is largely composed of the time domain analysis and the frequency analysis. In the former the flexibility of heart function is analysed, while in the latter autonomic nerve function is examined, which is the degree of sympathetic and parasympathetic nerve activity and the state of balance. Furthermore, existence or nonexistence of disease and/or level of stress can be estimated by measuring the variability and normality of heart rate, and balance of autonomic nerve system, and through HRV biofeedback the symptoms of anxiety disorder or asthma can be reduced.】
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Heart rate variability (HRV) is a noninvasive marker of cardiac autonomic activity and has been used in different circumstances to assess the autonomic responses of the body. Pulse rate variability (PRV), a similar variable obtained from pulse waves, has been used in recent years as a valid surrogate of HRV. However, the effect that localized changes in autonomic activity have in the relationship between HRV and PRV has not been entirely understood. In this study, a whole-body cold exposure protocol was performed to generate localized changes in autonomic activity, and HRV and PRV from different body sites were obtained. PRV measured from the earlobe and the finger was shown to differ from HRV, and the correlation between these variables was affected by the cold. Also, it was found that PRV from the finger was more affected by cold exposure than PRV from the earlobe. In conclusion, PRV is affected differently to HRV when localized changes in autonomic activity occur. Hence, PRV should not be considered as a valid surrogate of HRV under certain circumstances.Clinical Relevance- This indicates that pulse rate variability is affected differently to heart rate variability when autonomic activity is modified and suggests that pulse rate variability is not always a valid surrogate of heart rate variability.
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Objective: To test the hypothesis that heavy smoking is associated with a persistent increase in blood pressure Design: In 10 normotensive smokers asked to smoke one cigarette every 15 min for 1 h, blood pressure and heart rate were continuously monitored during the smoking period and during the preceding non-smoking hour. In six other normotensive smokers asked to smoke two cigarettes per hour throughout the whole day, blood pressure and heart rate were monitored non-invasively in ambulatory conditions for 8h (0900—700 h). Blood pressure monitoring was repeated during a non-smoking day Methods: Beat-to-beat blood pressure and heart rate were monitored at rest by means of the Finapres device. Blood pressure signal was sampled at 165 Hz by a computer to calculate hourly data. Ambulatory blood pressure and heart rate were measured once every 10 min Results: In resting conditions, the first cigarette caused an immediate and marked increase in blood pressure and heart rate, and the peak blood pressure and heart rate achieved were similar for the remaining three cigarettes. In each instance, the hemodynamic effects were so prolonged that throughout the smoking hour, blood pressure and heart rate were persistently higher than during the non-smoking hour. The standard deviations of systolic and diastolic blood pressure and heart rate were also higher during the smoking hour, indicating an increase in blood pressure and heart rate variability. In the six ambulant smokers, daytime blood pressure and heart rate were also persistently higher during smoking than during non-smoking Conclusions: Heavy smoking is associated with a persistent rise in blood pressure and also with an increase in blood pressure variability. These effects (which may escape clinic blood pressure measurements performed during non-smoking) may account for some of the smoking-related cardiovascular risk
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睡眠時無呼吸は, 加齢とともに増加する. 無呼吸指数 (AI) 5 (/時間) 以上を診断基準とすると, 65歳以上では20%以上が睡眠時無呼吸症候群 (SAS) であるとの報告もある. しかし, そのほとんどが無症状であり, 65歳以上まで生き長えられた高齢者では, いわゆる生存者効果により, SAS自体は予後に影響を示さない可能性が指摘される. 成人の持続陽圧呼吸 (CPAP) 適応基準が, そもそも高齢者にはそぐわない可能性が高く, 治療の必要性の是非が問われる. つぎにコンプライアンスの問題がある. 義歯, 下顎の不安定性などから, CPAP装着が困難なケースがある. たとえCPAPをしても口を開けてしまうケースもある. つまり, 高齢者では, SASと診断しても, 治療が絶対的に必要とは言えず, 多少の不便さを超えて在宅でCPAP治療を継続する意義が成人に比べて低いことが否めない. 睡眠状況, タバコや酒などの生活習慣, 運動習慣などを見直し, 睡眠の改善を先行すべきと考える.
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بررسی تغییرات طیف توان فرکانس سیگنال( Heart HRV Rate variability ) در بیماری شریان کرونری( CAD ) و مقایسه با نتیجه تست ورزش , بررسی تغییرات طیف توان فرکانس سیگنال( Heart HRV Rate variability ) در بیماری شریان کرونری( CAD )... , کتابخانه الکترونیک و دیجیتال - آذرسا
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Though immediate pain is reported by nearly all patients undergoing needle-EMG,little is known about its cardiovascular risk from changes in blood-pressure orheart-rate. This study was thus conducted to investigate if, and to whichdegree, blood-pressure and heart-rate are influenced by needle-EMG. In 50patients, 24 women, 26 men, aged 26–78 years, conventional needle-EMGs from 54muscles were recorded. Pain was assessed on a verbal analogue pain-scale (1–10)and blood-pressure and heart-rate were measured before, during and after EMG.Mean pain-ratings before, during and after EMG were 0.8, 4.1 and 1.0,respectively. Mean systolic/diastolic blood-pressure was 144/87mmHg before,145/86mmHg during and 144/87mmHg after EMG. Mean heart-rate before, during andafter EMG was 77, 77 and 78 beats/min, respectively. Systolic/diastolicblood-pressure increased above 145/85mmHg in only 2/6 patients during EMG. Theweak affection of blood-pressure and heart-rate by pain from needle-EMG wasfound in patients with and without hypertension. Mean blood-pressure, heart-rateand pain-ratings before, during and after EMG were independent of age, sex andmuscle. The correlation between pain-ratings and blood-pressure and heart-ratewas not significant. This study shows that needle-EMG moderately hurts but doesnot increase blood-pressure or heart-rate, irrespective of known arterialhypertension. Based upon these findings, the cardiovascular risk of needle-EMGfrom changes in blood-pressure or heart-rate is regarded negligibly low.
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Η χρόνια νεφρική ανεπάρκεια αποτελεί μια από τις κύριες αιτίες νοσηρότητας και θνητότητας. Η επίπτωση της χρόνιας νεφρικής νόσου είναι μεγαλύτερη σε διαβητικά σε σχέση με μη διαβητικά άτομα. Σε ασθενείς με χρόνια νεφρική ανεπάρκεια τελικού σταδίου τα καρδιαγγειακά νοσήματα αποτελούν την κύρια αιτία θανάτου. Τις τελευταίες δυο δεκαετίες έχει καταδειχθεί μια σημαντική συσχέτιση μεταξύ της δυσλειτουργίας του ΑΝΣ και της καρδιαγγειακής θνησιμότητας. Η HRV είναι ένας μη επεμβατικός ηλεκτροκαρδιογραφικός δείκτης που αντικατοπτρίζει τη δραστηριότητα του συμπαθητικού και παρασυμπαθητικού τμήματος του ΑΝΣ στο επίπεδο του καρδιακού φλεβοκόμβου. Η ελαττωμένη HRV έχει καθιερωθεί ως σημαντικός ανεξάρτητος παράγοντας κινδύνου για υψηλότερη ολική και καρδιαγγειακή θνησιμότητα στην καρδιαγγειακή νόσο αλλά και σε υγιείς πληθυσμούς. Οι μελέτες ασθενών με χρόνια νεφρική ανεπάρκεια τελικού σταδίου έδειξαν μείωση της HRV, η οποία συνδέεται με αυξημένο κίνδυνο ολικής θνησιμότητας και αιφνίδιου καρδιακού θανάτου. Παραδόξως μέχρι σήμερα δεν υπάρχουν μελέτες που να αναφέρονται στην μακροχρόνια επίδραση της χρόνιας περιοδικής αιμοκάθαρσης στη HRV σε ασθενείς με χρόνια νεφρική ανεπάρκεια τελικού σταδίου, διαβητικούς ή μη. Στην παρούσα μελέτη 1) εξετάσθηκε κατά πόσον η εφαρμογή τρισεβδομαδιαίας τετράωρης περιοδικής αιμοκάθαρσης επί τρίμηνο, σε διαβητικούς και μη ασθενείς με χρόνια νεφρική ανεπάρκεια τελικού σταδίου, επηρέασε τις time- και frequency-domain παραμέτρους της HRV, 2) διερευνήθηκε η ύπαρξη συσχετίσεων μεταξύ των time- και frequency- domain παραμέτρων της HRV αφενός με κλινικοεργαστηριακά ευρήματα και αφετέρου με κλασσικούς και νεότερους παράγοντες καρδιαγγειακού κινδύνου στον ανωτέρω πληθυσμό και 3) έγινε προσπάθεια διαμόρφωσης ενός μοντέλου πρόγνωσης διαταραχών της HRV βάσει των δεδομένων του ατομικού αναμνηστικού και των κλινικοεργαστηριακών ευρημάτων των ανωτέρω ασθενών. Στους νεφροπαθείς ασθενείς με ή χωρίς ΣΔ και στους διαβητικούς ασθενείς χωρίς νεφρική ανεπάρκεια διαπιστώθηκε σημαντικά μειωμένη HRV, με τη δραματικότερη μείωση να παρατηρείται στους ασθενείς με συνυπάρχουσα χρόνια νεφρική ανεπάρκεια και ΣΔ. Οι νεφροπαθείς ασθενείς με ή χωρίς ΣΔ, μετά την ένταξή τους σε χρόνιο πρόγραμμα περιοδικής αιμοκάθαρσης, βελτίωσαν σημαντικά τις time-domain παραμέτρους της HRV, με τη μεγαλύτερη βελτίωση να παρατηρείται στους νεφροπαθείς χωρίς ΣΔ, ενώ οι frequency-domain παράμετροι παρέμειναν αμετάβλητες. Στη μελέτη μας διαπιστώθηκε σημαντική συσχέτιση των παραμέτρων της HRV αφενός μεν με κλασσικούς παράγοντες καρδιαγγειακού κινδύνου όπως η ηλικία, το ιστορικό αρτηριακής υπέρτασης και καρδιακής νόσου, ο ΣΔ, η νεφρική νόσος και η δυσλιπιδαιμία, αφετέρου δε με νεότερους παράγοντες καρδιαγγειακόυ κινδύνου όπως τα λευκά αιμοσφαίρια, η αντίσταση στην ινσουλίνη, η hs-CRP, το NT-proBNP, η MGP και το οξειδωτικό stress. Διαπιστώθηκε θετική σημαντική συσχέτιση των παραμέτρων της HRV με τα ολικά λευκώματα και την λευκωματίνη ορού και με τα επίπεδα νατρίου και ασβεστίου ορού, ενώ διαπιστώθηκε αρνητική σημαντική συσχέτιση με την περίμετρο μέσης, τη HbA1c, με τα επίπεδα καλίου και φωσφόρου ορού και το ουρικό οξύ.
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