Berg Robert Allen, Hilwig Ronald Willard, Kern Karl B, Ewy Gordon Allen
Steele Memorial Children's Research Center and the Department of Pediatrics, University of Arizona College of Medicine, Tucson 85724-5073, USA.
Ann Emerg Med. 2002 Dec;40(6):563-70. doi: 10.1067/mem.2002.129866.
After prolonged ventricular fibrillation (VF), precountershock cardiopulmonary resuscitation (CPR) will improve myocardial "readiness" for defibrillation compared with immediate defibrillation.
After 10 minutes of untreated VF, 32 swine (27+/-1 kg) were randomly assigned to receive immediate countershocks (DEFIB), CPR for 3 minutes followed by countershocks (CPR), or CPR for 3 minutes plus intravenous epinephrine followed by countershocks (CPR+EPI). VF waveform was evaluated by fast Fourier transformation.
VF amplitude and median frequency by fast Fourier transformation decreased during the untreated VF interval in all groups, and the median frequency subsequently increased during each minute of precountershock CPR. Although the VF median frequency in the 3 groups did not differ after 10 minutes of untreated VF (8.9+/-0.8 Hz versus 8.4+/-0.5 Hz versus 7.3+/-0.5 Hz, respectively), immediately before the first shock the VF median frequency was much lower in the DEFIB group than in either the CPR or CPR+EPI groups (8.9+/-0.8 Hz versus 13.1+/-0.8 Hz versus 13.8+/-0.9 Hz, respectively; P <.01). None of the 10 animals in the DEFIB group attained return of spontaneous circulation after the first set of shocks versus 5 of 10 animals in the CPR group and 6 of 12 animals in the CPR+EPI group (DEFIB versus each CPR group; P <.05). Cardiac output 1 hour after resuscitation was substantially worse in the DEFIB group than in the CPR or CPR+EPI groups (74+/-7 mL/kg per minute versus 119+/-7 mL/kg per minute versus 104+/-15 mL/kg per minute; P <.05).
Precountershock CPR can result in substantial physiologic benefits compared with immediate defibrillation in the setting of prolonged VF. Moreover, these benefits can be attained with or without the addition of intravenous epinephrine.
与立即除颤相比，在长时间心室颤动（VF）后，电击前进行心肺复苏（CPR）将改善心肌对除颤的“准备状态”。
在未经处理的VF持续10分钟后，将32头猪（27±1 kg）随机分为三组，分别接受立即电击（DEFIB）、先进行3分钟CPR再电击（CPR）或先进行3分钟CPR加静脉注射肾上腺素再电击（CPR+EPI）。通过快速傅里叶变换评估VF波形。
在所有组中，未经处理的VF间期内，通过快速傅里叶变换测得的VF振幅和中位频率均下降，且在电击前的每一分钟CPR过程中，中位频率随后增加。尽管在未经处理的VF持续10分钟后，三组的VF中位频率无差异（分别为8.9±0.8 Hz、8.4±0.5 Hz和7.3±0.5 Hz），但在首次电击前，DEFIB组的VF中位频率远低于CPR组或CPR+EPI组（分别为8.9±0.8 Hz、13.1±0.8 Hz和13.8±0.9 Hz；P<.01）。DEFIB组的10只动物在首次电击后均未恢复自主循环，而CPR组的10只动物中有5只恢复，CPR+EPI组的12只动物中有6只恢复（DEFIB组与各CPR组相比；P<.05）。复苏后1小时，DEFIB组的心输出量显著低于CPR组或CPR+EPI组（分别为74±7 mL/kg每分钟、119±7 mL/kg每分钟和104±15 mL/kg每分钟；P<.05）。
在长时间VF情况下，与立即除颤相比，电击前进行CPR可带来显著的生理益处。此外，无论是否添加静脉注射肾上腺素均可获得这些益处。
