Pickham David, Helfenbein Eric, Shinn Julie A, Chan Garrett, Funk Marjorie, Drew Barbara J
Department of Physiological Nursing, University of California San Francisco, San Francisco, CA, USA.
J Electrocardiol. 2010 Nov-Dec;43(6):572-6. doi: 10.1016/j.jelectrocard.2010.05.016.
Recent Scientific Statement from the American Heart Association (AHA) recommends that hospital patients should receive QT interval monitoring if certain conditions are present: QT-prolonging drug administration or admission for drug overdose, electrolyte disturbances (K, Mg), and bradycardia. No studies have quantified the proportion of critical care patients that meet the AHA's indications for QT interval monitoring. This is a prospective study of 1039 critical care patients to determine the proportion of patients that meet the AHA's indications for QT interval monitoring. Secondary aim is to evaluate the predictive value of the AHA's indications in identifying patients who actually develop QT interval prolongation.
Continuous QT interval monitoring software was installed in all monitored beds (n = 154) across 5 critical care units. This system uses outlier rejection and median filtering in all available leads to construct an root-mean-squared wave from which the QT measurement is made. Fridericia formula was used for heart rate correction. A QT interval greater than 500 milliseconds for 15 minutes or longer was considered prolonged for analyses. To minimize false positives all episodes of QT prolongation were manually over read. Clinical data was abstracted from the medical record.
Overall 69% of patients had 1 or more AHA indications for QT interval monitoring. More women (74%) had indications than men (64%, P = .001). One quarter (24%) had QT interval prolongation (>500 ms for ≥15 minutes). The odds for QT interval prolongation increased with the number of AHA indications present; 1 indication, odds ratio (OR) = 3.2 (2.1-5.0); 2 indications, OR = 7.3(4.6-11.7); and 3 or more indications OR = 9.2(4.8-17.4). Positive predictive value of the AHA indications for QT interval prolongation was 31.2%; negative predictive value was 91.3%.
Most critically ill patients (69%) have AHA indications for QT interval monitoring. One quarter of critically ill patients (24%) developed QT interval prolongation. The AHA indications for QT interval monitoring successfully captured the majority of critically ill patients developing QT interval prolongation.
美国心脏协会（AHA）最近的科学声明建议，如果存在某些情况，医院患者应接受QT间期监测：使用延长QT间期的药物或因药物过量入院、电解质紊乱（钾、镁）以及心动过缓。尚无研究对符合AHA QT间期监测指征的重症监护患者比例进行量化。这是一项针对1039例重症监护患者的前瞻性研究，旨在确定符合AHA QT间期监测指征的患者比例。次要目的是评估AHA指征在识别实际发生QT间期延长患者方面的预测价值。
在5个重症监护病房的所有监测床位（n = 154）安装了连续QT间期监测软件。该系统在所有可用导联中使用异常值剔除和中位数滤波来构建均方根波，并据此进行QT测量。采用弗里德里西亚公式进行心率校正。分析时，QT间期大于500毫秒持续15分钟或更长时间被视为延长。为尽量减少假阳性，所有QT延长发作均进行人工复查。临床数据从病历中提取。
总体而言，69%的患者有1项或更多AHA的QT间期监测指征。有指征的女性（74%）多于男性（64%，P = 0.001）。四分之一（24%）的患者出现QT间期延长（≥15分钟时>500毫秒）。QT间期延长的几率随AHA指征数量的增加而增加；1项指征，比值比（OR）= 3.2（2.1 - 5.0）；2项指征，OR = 7.3（4.6 - 11.7）；3项或更多指征，OR = 9.2（4.8 - 17.4）。AHA指征对QT间期延长的阳性预测值为31.2%；阴性预测值为91.3%。
大多数重症患者（69%）有AHA的QT间期监测指征。四分之一的重症患者（24%）出现了QT间期延长。AHA的QT间期监测指征成功识别了大多数发生QT间期延长的重症患者。
