Goal-directed fluid management based on stroke volume variation and stroke volume optimization during high-risk surgery: a pilot multicentre randomized controlled trial

Introduction: Perioperative hemodynamic optimization has been shown to be useful to improve the postoperative outcome of patients undergoing major surgery. We designed a pilot study in patients undergoing major abdominal, urologic or vascular surgery to investigate the effects of a goal-directed (GD) fluid management based on continuous stroke volume variation (SVV) and stroke volume (SV) monitoring on postoperative outcomes. Methods: Fifty-two high-risk-surgical patients (ASA 3 or 4, arterial and central venous catheter in place, postoperative admission in ICU) were randomized either to a control group (Group C, n = 26) or to a goal-directed group (Group G, n = 26). Patients with cardiac arrhythmia or ventilated with a tidal volume <7 ml/kg were excluded. In Group G, SVV and SV were continuously monitored with the FloTrac™/Vigileo™ system (Edwards Lifesciences, USA) and patients were brought to and maintained on the plateau of the Frank-Starling curve (SVV <10% and SV increase <10% in response to fluid loading). During the ICU stay, organ dysfunction was assessed using the SOFA score and resource utilization using the TISS score. Patients were followed up to 28 days after surgery for infectious, cardiac, respiratory, renal, hematologic and abdominal complications. Results: Group G and Group C were comparable for ASA score, comorbidities, type and duration of surgery (275 vs. 280 minutes), heart rate, MAP and CVP at the start of surgery. However, Group G was younger than Group C (68 vs. 73 years, P < 0.05). During surgery, Group G received more colloids than Group C (1,589 vs. 927 ml, P < 0.05) and SVV decreased in Group G (from 9.0 to 8.0%, P < 0.05) but not in Group C. The number of postoperative wound infections was lower in Group G (0 vs. 7, P < 0.01). Although not statistically significant, the proportion of patients with at least one complication (46 vs. 62%), the number of postoperative complications per patient (0.65 vs. 1.40), the maximum ICU SOFA score (5.9 vs. 7.2), and the cumulative ICU TISS score (69 vs. 83) were also lower in Group G. ICU and hospital length of stay were similar in both groups. Conclusion: Although the two groups were not perfectly matched, this pilot shows that fluid management based on SVV and SV optimization decreases wound infections. It also suggests that such a GD strategy may decrease postoperative organ dysfunction and resource utilization. However, this remains to be confirmed by a larger study

A "NIRS" death experience: a reduction in cortical oxygenation by time-resolved near-infrared spectroscopy preceding cardiac arrest

Near-infrared spectroscopy (NIRS) has been used effectively post-cardiac-arrest to gauge adequacy of resuscitation and predict the likelihood of achieving a return of spontaneous circulation. However, preempting hemodynamic collapse is preferable to achieving ROSC through advanced cardiac life support. Minimizing "time down" without end-organ perfusion has always been a central pillar of ACLS. In many critically ill patients there is a prolonged phase of end-organ hypoperfusion preceding loss of palpable pulses and initiation of ACLS. Due to the relative infrequency of in-hospital cardiac arrest, NIRS has not previously evaluated the period immediately prior to hemodynamic collapse. Here we report a young man who suffered a pulseless electrical activity (PEA) arrest while cortical oxygenation was monitored using time-resolved near-infrared spectroscopy. The onset of cortical deoxygenation preceded the loss of palpable pulses by 15 min, suggesting that TRS-NIRS monitoring might provide a means of preempting PEA arrest. Our experience with this patient represents a promising new direction for continuous NIRS monitoring and has the potential to not only predict clinical outcomes, but affect them to the patient's benefit as well

Journal of Clinical Monitoring and Computing 2015 end of year summary:tissue oxygenation and microcirculation

Last year we started this series of end of year summaries of papers published in the 2014 issues of the Journal Of Clinical Monitoring And Computing with a review on near infrared spectroscopy (Scheeren et al. in J Clin Monit Comput 29(2):217-220, 2015). This year we will broaden the scope and include papers published in the field of tissue oxygenation and microcirculation, or a combination of both entities. We present some promising new technologies that might enable a deeper insight into the (patho)physiology of certain diseases such as sepsis, but also in healthy volunteers. These may help researchers and clinicians to evaluate both tissue oxygenation and microcirculation beyond macro-hemodynamic measurements usually available at the bedside

Journal of clinical monitoring and computing 2016 end of year summary:monitoring cerebral oxygenation and autoregulation

In the perioperative and critical care setting, monitoring of cerebral oxygenation (ScO2) and cerebral autoregulation enjoy increasing popularity in recent years, particularly in patients undergoing cardiac surgery. Monitoring ScO2 is based on near infrared spectroscopy, and attempts to early detect cerebral hypoperfusion and thereby prevent cerebral dysfunction and postoperative neurologic complications. Autoregulation of cerebral blood flow provides a steady flow of blood towards the brain despite variations in mean arterial blood pressure (MAP) and cerebral perfusion pressure, and is effective in a MAP range between approximately 50-150 mmHg. This range of intact autoregulation may, however, vary considerably between individuals, and shifts to higher thresholds have been observed in elderly and hypertensive patients. As a consequence, intraoperative hypotension will be poorly tolerated, and might cause ischemic events and postoperative neurological complications. This article summarizes research investigating technologies for the assessment of ScO2 and cerebral autoregulation published in the Journal of Clinical Monitoring and Computing in 2016

Journal of Clinical Monitoring and Computing 2017/2018 end of year summary:monitoringand provocationof the microcirculation and tissue oxygenation

The microcirculation is the ultimate goal of hemodynamic optimization in the perioperative and critical care setting. In this fourth end-of-year summary of the Journal of Clinical Monitoring and Computing on this topic, we take a closer look at papers published in the last 2years that focus on this important aspect. The majority of these papers investigated the use of either cerebral or peripheral tissue oxygen saturation, derived non-invasively using near infrared spectroscopy (NIRS). In some of these studies, the microcirculation was provocated by inducing short-term tissue hypoxia, allowing the assessment of functional microvascular reserve. Additionally, studies on technical differences between NIRS monitors are summarized, as well as studies investigating the feasibility of NIRS monitoring, mainly in the pediatric patient population. Last but not least, novel monitoring tools allow assessing oxygenation at a (sub)cellular level, and those papers incorporating these techniques are also reviewed here

The effect of fluid resuscitation on the effective circulating volume in patients undergoing liver surgery: a post-hoc analysis of a randomized controlled trial

To assess the significance of an analogue of the mean systemic filling pressure (Pmsa) and its derived variables, in providing a physiology based discrimination between responders and non-responders to fluid resuscitation during liver surgery. A post-hoc analysis of data from 30 patients undergoing major hepatic surgery was performed. Patients received 15 ml kg(-1) fluid in 30 min. Fluid responsiveness (FR) was defined as an increase of 20% or greater in cardiac index, measured by FloTrac-Vigileo((R)). Dynamic preload variables (pulse pressure variation and stroke volume variation: PPV, SVV) were recorded additionally. Pvr, the driving pressure for venous return (=Pmsa-central venous pressure) and heart performance (EH; Pvr/Pmsa) were calculated according to standard formula. Pmsa increased following fluid administration in responders (n = 18; from 13 +/- 3 to 17 +/- 4 mmHg, p < 0.01) and in non-responders (n = 12; from 14 +/- 4 to 17 +/- 4 mmHg, p < 0.01). Pvr, which was lower in responders before fluid administration (6 +/- 1 vs. 7 +/- 1 mmHg; p = 0.02), increased after fluid administration only in responders (from 6 +/- 1 to 8 +/- 1 mmHg; p < 0.01). EH only decreased in non-responders (from 0.56 +/- 0.17 to 0.45 +/- 0.12; p < 0.05). The area under the receiver operating characteristics curve of Pvr, PPV and SVV for predicting FR was 0.75, 0.73 and 0.72, respectively. Changes in Pmsa, Pvr and EH reflect changes in effective circulating volume and heart performance following fluid resuscitation, providing a physiologic discrimination between responders and non-responders. Also, Pvr predicts FR equivalently compared to PPV and SVV, and might therefore aid in predicting FR in case dynamic preload variables cannot be used

Photoplethysmography for blood volumes and oxygenation changes during intermittent vascular occlusions

Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO[Formula: see text]) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO[Formula: see text] for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated ([Formula: see text]HbO[Formula: see text]), reduced ([Formula: see text]HHb) and total haemoglobin ([Formula: see text]tHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer-Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A[Formula: see text] = [Formula: see text]A[Formula: see text] - [Formula: see text]A[Formula: see text]) and by the conventional SpO[Formula: see text]. The [Formula: see text]HbO[Formula: see text], [Formula: see text]HHb, [Formula: see text]tHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p < 0.05). The trends in the variables extracted from PPG showed good correlation with the same parameters measured by the reference NIRS monitor. Bland and Altman analysis of agreement between PPG and NIRS showed underestimation of the magnitude of changes by the PPG. A[Formula: see text] indicated significant changes for occlusion pressures exceeding 20 mmHg (p < 0.05) and correlation with tissue oxygenation changes measured by NIRS, while SpO[Formula: see text] had significant changes after 40 mmHg (p < 0.05). Relative changes in haemoglobin concentrations can be estimated from PPG signals and they showed a good level of accuracy in the detection of perfusion and oxygenation changes induced by different degrees of intermittent vascular occlusions. These results can open up to new applications of the PPG waveform in the detection of blood volumes and oxygenation changes