Nilsson L, Johansson A, Kalman S
Department of Anaesthesiology and Intensive Care, Linköping University Hospital, Linköping, Sweden.
Physiol Meas. 2003 Nov;24(4):925-37. doi: 10.1088/0967-3334/24/4/009.
Photoplethysmography (PPG) is a non-invasive optical technique sensitive to variations in blood volume and perfusion in the tissue. Reflection mode PPG may have clinical advantages over transmission mode PPG. To improve clinical usefulness and further development of the reflection mode PPG, studies on factors that modify the signal are warranted. We studied the coherence between the respiratory induced intensity variations (RIIV) of the PPG signal and respiratory synchronous pressure variations in central venous pressure (CVP), peripheral venous pressure (PVP) and arterial blood pressure (ABP) during positive pressure ventilation on 12 patients under anaesthesia and on 12 patients with spontaneous breathing. During positive pressure ventilation the coherence between all signals was high. Inspiration was followed first by an increase in CVP, then by increases in ABP and PVP and lastly by RIIV indicating less back-scattered light. In spontaneously breathing patients the coherence was high, but the phases between the signals were changed. During inspiration, ABP decreased slightly before CVP, followed by a decrease in RIIV and PVP. The phase relation between RIIV and respiratory induced variation in macrocirculation changed with ventilatory mode, but not in a uniform way, indicating the influence of mechanisms other than macrocirculation involved in generating the RIIV signal.
光电容积脉搏波描记法（PPG）是一种对组织中血容量和灌注变化敏感的非侵入性光学技术。反射式PPG可能比透射式PPG具有临床优势。为提高反射式PPG的临床实用性并促进其进一步发展，有必要对影响该信号的因素进行研究。我们研究了12例麻醉患者和12例自主呼吸患者在正压通气期间PPG信号的呼吸诱导强度变化（RIIV）与中心静脉压（CVP）、外周静脉压（PVP）和动脉血压（ABP）的呼吸同步压力变化之间的相关性。在正压通气期间，所有信号之间的相关性都很高。吸气后，首先是CVP升高，然后是ABP和PVP升高，最后是RIIV升高，表明背向散射光减少。在自主呼吸患者中，相关性也很高，但信号之间的相位发生了变化。吸气时，ABP在CVP之前略有下降，随后是RIIV和PVP下降。RIIV与呼吸诱导的体循环变化之间的相位关系随通气模式而改变，但并非以统一的方式改变，这表明除体循环外，还有其他机制参与了RIIV信号的产生。
