Khan Nouman U, Strang Tim, Bonsheck Claire, Krishnamurty Bhuvana, Hooper Timothy L
Department of Cardiothoracic surgery and Anaesthesia, University Hospital of South Manchester NHS Foundation Trust, Wythenshawe Hospital, Southmoor Road, Manchester M23 9LT, United Kingdom. n u
Resuscitation. 2008 Jun;77(3):374-8. doi: 10.1016/j.resuscitation.2008.02.003. Epub 2008 Mar 25.
Haemodynamically significant ventricular tachyarrhythmias are a frequent complication in the immediate post-operative period after cardiac surgery. Successful cardioversion depends on delivery of sufficient current, which in turn is dependent on transthoracic impedance (TTI). However, it is uncertain if there is a change in TTI immediately following cardiac surgery using cardiopulmonary bypass (CPB).
TTI was measured on 40 patients undergoing first time isolated cardiac surgery using CPB. TTI was recorded at 30 kHz using Bodystat Multiscan 5000 equipment before operation (with and without a positive end-expiratory pressure (PEEP) of 5 cm of H(2)O) and then at 1, 4 and 24 h after the operation. Data was analyzed to determine the relationship between pre- and post-operative variables and TTI values.
Mean pre-operative TTI was 54.5+/-10.55 ohms without PEEP and 61.8+/-15.4 ohms on a PEEP of 5 cm of H(2)O. TTI dropped significantly (p<0.001) after the operation to 47.2+/-10.6 ohms at 1 h, 42.6+/-10.2 ohms at 4 h and 41.8+/-10.4 ohms at 24 h. A positive correlation was noted between duration of operation and TTI change at 1 h (r=0.38; p=0.016). There was no significant correlation between the duration of bypass and change in TTI.
TTI decreases by more than 30% in the immediate post-operative period following cardiac surgery. This state may favour defibrillation at lower energy levels.
血流动力学显著的室性心律失常是心脏手术后即刻常见的并发症。成功的心脏复律取决于足够电流的输送，而这又取决于经胸阻抗（TTI）。然而，使用体外循环（CPB）进行心脏手术后TTI是否会立即发生变化尚不确定。
对40例首次接受CPB心脏直视手术的患者测量TTI。在手术前（使用和不使用5 cmH₂O的呼气末正压（PEEP））使用Bodystat Multiscan 5000设备在30 kHz下记录TTI，然后在术后1、4和24小时记录。分析数据以确定术前和术后变量与TTI值之间的关系。
术前平均TTI在不使用PEEP时为54.5±10.55欧姆，在5 cmH₂O的PEEP下为61.8±15.4欧姆。术后TTI显著下降（p<0.001），在1小时时降至47.2±10.6欧姆，4小时时降至42.6±10.2欧姆，24小时时降至41.8±10.4欧姆。手术时间与1小时时TTI变化之间存在正相关（r=0.38；p=0.016）。体外循环时间与TTI变化之间无显著相关性。
心脏手术后即刻TTI下降超过30%。这种状态可能有利于在较低能量水平下进行除颤。
