Preisman S, Pfeiffer U, Lieberman N, Perel A
Department of Anesthesiology and Intensive Care, Sheba Medical Center, Sackler School of Medicine, Tel Aviv University, Tel Hashomer, Israel.
Intensive Care Med. 1997 Jun;23(6):651-7. doi: 10.1007/s001340050389.
Two new monitoring techniques, the analysis of arterial pressure waveform during mechanical ventilation and the determination of intrathoracic blood volume, were evaluated for preload assessment in a model of graded hemorrhage.
8 anesthetized dogs bled of 10, 20, and 30% of their blood volume, then retransfused and volume loaded with plasma expander. Central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac output, parameters of the arterial pressure waveform analysis [systolic pressure variation (SPV) and delta down (dDOWN)], and intrathoracic blood volume (ITBV) were measured at baseline and after each stage of hemorrhage and volume expansion.
The stroke volume index decreased significantly from 1.3 +/- 0.4 ml/kg at baseline to 0.7 +/- 0.2 ml/kg at 30% hemorrhage and then increased after retransfusion and volume loading. The changes in the filling pressures during the various stages of hemorrhage were in the range of 1-2 mmHg. CVP decreased from 5.5 +/- 0.9 to 3.1 +/- 1.7 mmHg and PCWP from 8.0 +/- 0.8 to 5.1 +/- 1.2 mmHg at 30% hemorrhage. Both filling pressures responded significantly to retransfusion; PCWP also changed in response to a volume load. SPV and dDOWN (expressed as percent of the systolic blood pressure during a short apnea) increased significantly from 6.7 +/- 1.7 and 5.6 +/- 3.2%, respectively, at baseline, to 9.7 +/- 2.6 and 8.1 +/- 2.9% after 10% blood loss and to 13.1 +/- 3.9 and 11.1 +/- 3.8% after 30% hemorrhage. ITBV decreased significantly from 29.7 +/- 4.5 to 26.8 +/- 5.3 ml/kg after 10% blood loss and to 23.1 +/- 3.0 ml/kg after 30% hemorrhage. ITBV, SPV, and dDOWN responded significantly to retransfusion and volume load. Significant correlations were found between the degree of volume change and dDOWN (r = 0.93), SPV (r = 0.96), ITBV (r = 0.95), CVP (r = 0.82), and PCWP (r = 0.90).
The parameters of arterial pressure waveform analysis (SPV and dDOWN) and ITBV were sensitive estimates of cardiac preload during the early stages of hemorrhage. Measurement of SPV and dDOWN, being both sensitive and relatively noninvasive, has advantages over other methods of preload assessment but is limited to patients on controlled mechanical ventilation. ITBV, which supplies quantitative information about cardiac preload, is more invasive but can also be used in patients who are breathing spontaneously or who are on partial ventilatory support.
在分级出血模型中，评估两种新的监测技术，即机械通气期间动脉压波形分析和胸内血容量测定，用于预负荷评估。
8只麻醉犬分别放血10%、20%和30%血容量，然后再输血并用血浆扩容剂进行容量负荷。在基线以及出血和容量扩充的每个阶段后，测量中心静脉压（CVP）、肺毛细血管楔压（PCWP）、心输出量、动脉压波形分析参数[收缩压变异（SPV）和下降差值（dDOWN）]以及胸内血容量（ITBV）。
每搏量指数从基线时的1.3±0.4 ml/kg显著降至30%出血时的0.7±0.2 ml/kg，然后在再输血和容量负荷后增加。出血各阶段充盈压的变化范围为1 - 2 mmHg。30%出血时，CVP从5.5±0.9 mmHg降至3.1±1.7 mmHg，PCWP从8.0±0.8 mmHg降至5.1±1.2 mmHg。两种充盈压对再输血均有显著反应；PCWP对容量负荷也有变化。SPV和dDOWN（表示为短暂呼吸暂停期间收缩压的百分比）从基线时分别为±6.7 1.7%和5.6±3.2%，显著增加至失血10%后为9.7±2.6%和8.1±2.9%，30%出血后为13.1±3.9%和11.1±3.8%。ITBV在失血10%后从29.7±4.5显著降至26.8±5.3 ml/kg，30%出血后降至23.1±3.0 ml/kg。ITBV、SPV和dDOWN对再输血和容量负荷均有显著反应。在容量变化程度与dDOWN（r = 0.93）、SPV（r = 0.96）、ITBV（r = 0.95）、CVP（r = 0.82）和PCWP（r = 0.90）之间发现显著相关性。
动脉压波形分析参数（SPV和dDOWN）以及ITBV在出血早期是心脏预负荷的敏感估计指标。SPV和dDOWN的测量既敏感又相对无创，比其他预负荷评估方法具有优势，但仅限于接受控制性机械通气的患者。ITBV可提供有关心脏预负荷的定量信息，虽更具侵入性，但也可用于自主呼吸或接受部分通气支持的患者。
