Make my haemodynamic monitor GREEN: sustainable monitoring solutions.

Anaesthesiologists overwhelmingly favour pulse wave analysis techniques as their primary method to monitor cardiac output during high-risk noncardiac surgery. In patients with a radial arterial catheter in place, pulse wave analysis techniques have the advantage of instantly providing non-operator-dependent and continuous haemodynamic monitoring information. Green pulse wave analysis techniques working with any standard pressure transducer are as reliable as techniques requiring dedicated pressure transducers. They have the advantage of minimising plastic waste and related carbon dioxide emissions, and also significantly reducing hospital costs. The future integration of pulse wave analysis algorithms into multivariable bedside monitors, obviating the need for standalone haemodynamic monitors, could lead to wider use of haemodynamic monitoring solutions by further reducing their cost and carbon footprint.

Haemodynamic monitoring during noncardiac surgery: past, present, and future.

During surgery, various haemodynamic variables are monitored and optimised to maintain organ perfusion pressure and oxygen delivery - and to eventually improve outcomes. Important haemodynamic variables that provide an understanding of most pathophysiologic haemodynamic conditions during surgery include heart rate, arterial pressure, central venous pressure, pulse pressure variation/stroke volume variation, stroke volume, and cardiac output. A basic physiologic and pathophysiologic understanding of these haemodynamic variables and the corresponding monitoring methods is essential. We therefore revisit the pathophysiologic rationale for intraoperative monitoring of haemodynamic variables, describe the history, current use, and future technological developments of monitoring methods, and finally briefly summarise the evidence that haemodynamic management can improve patient-centred outcomes.

Intraoperative blood pressure: could less be more?

Retrospective observational studies have reported a significant association between intraoperative hypotension and postoperative morbidity. However, association does not imply causation, and whether preventing intraoperative hypotension can improve patient outcome remains to be demonstrated. In this issue of the British Journal of Anaesthesia, D'Amico and colleagues meta-analysed 10 prospective randomised trials comparing low (≤60 mm Hg) and higher mean arterial pressure targets during anaesthesia and surgery. They did not observe an increase in postoperative morbidity and mortality in the low target group. In contrast, they reported a statistically significant (but not clinically relevant) reduction in postoperative cardiac arrhythmia and hospital length of stay when targeting mean arterial pressure ≤60 mm Hg. These findings suggest that during most surgical cases, intraoperative hypotension is a marker of the severity, frailty, or both rather than a mediator of postoperative complications.

Pulse contour techniques for perioperative hemodynamic monitoring: A nationwide carbon footprint and cost estimation.

BACKGROUND: The question of environmentally sustainable perioperative medicine represents a new challenge in an era of cost constraints and climate crisis. The French Society of Anaesthesia and Intensive Care (SFAR) recommends stroke volume optimization in high-risk surgical patients. Pulse contour techniques have become increasingly popular for stroke volume monitoring during surgery. Some require the use of specific disposable pressure transducers (DPTs), whereas others can be used with standard DPTs. OBJECTIVE: Quantify and compare the carbon footprint and cost of pulse contour techniques using specific and standard DPTs on a yearly basis and at a national level. METHODS: We estimated the number of high-risk surgical patients monitored every year in France with a pulse contour technique, and the plastic waste, carbon footprint and cost associated with the use of specific and standard DPTs. MAIN FINDINGS: When compared to pulse contour techniques working with a standard DPT, techniques requiring a specific DPT are responsible for an increase in carbon dioxide emission estimated at 65-83 tons/yr and for additional hospital cost estimated at €67 million/yr. If, as recommended by the SFAR, all high-risk surgical patients were monitored, the difference would reach 179-227 tons/yr for the environmental impact and €187 million/yr for the economic impact. CONCLUSION: From an environmental and economic standpoint, pulse contour techniques working with standard DPTs should be recommended for the perioperative hemodynamic monitoring of high-risk surgical patients.

Evaluation of a new smartphone optical blood pressure application (OptiBP™) in the post-anesthesia care unit: a method comparison study against the non-invasive automatic oscillometric brachial cuff as the reference method.

We compared blood pressure (BP) values obtained with a new optical smartphone application (OptiBP™) with BP values obtained using a non-invasive automatic oscillometric brachial cuff (reference method) during the first 2 h of surveillance in a post-anesthesia care unit in patients after non-cardiac surgery. Three simultaneous BP measurements of both methods were recorded every 30 min over a 2-h period. The agreement between measurements was investigated using Bland-Altman and error grid analyses. We also evaluated the performance of the OptiBP™ using ISO81060-2:2018 standards which requires the mean of the differences ± standard deviation (SD) between both methods to be less than 5 mmHg ± 8 mmHg. Of 120 patients enrolled, 101 patients were included in the statistical analysis. The Bland-Altman analysis demonstrated a mean of the differences ± SD between the test and reference methods of + 1 mmHg ± 7 mmHg for mean arterial pressure (MAP), + 2 mmHg ± 11 mmHg for systolic arterial pressure (SAP), and + 1 mmHg ± 8 mmHg for diastolic arterial pressure (DAP). Error grid analysis showed that the proportions of measurement pairs in risk zones A to E were 90.3% (no risk), 9.7% (low risk), 0% (moderate risk), 0% (significant risk), 0% (dangerous risk) for MAP and 89.9%, 9.1%, 1%, 0%, 0% for SAP. We observed a good agreement between BP values obtained by the OptiBP™ system and BP values obtained with the reference method. The OptiBP™ system fulfilled the AAMI validation requirements for MAP and DAP and error grid analysis indicated that the vast majority of measurement pairs (≥ 99%) were in risk zones A and B.Trial Registration ClinicalTrials.gov Identifier: NCT04262323.

Wireless wearables for postoperative surveillance on surgical wards: a survey of 1158 anaesthesiologists in Western Europe and the USA.

Background: Several continuous monitoring solutions, including wireless wearable sensors, are available or being developed to improve patient surveillance on surgical wards. We designed a survey to understand the current perception and expectations of anaesthesiologists who, as perioperative physicians, are increasingly involved in postoperative care. Methods: The survey was shared in 40 university hospitals from Western Europe and the USA. Results: From 5744 anaesthesiologists who received the survey link, there were 1158 valid questionnaires available for analysis. Current postoperative surveillance was mainly based on intermittent spot-checks of vital signs every 4-6 h in the USA (72%) and every 8-12 h in Europe (53%). A majority of respondents (91%) considered that continuous monitoring of vital signs should be available on surgical wards and that wireless sensors are preferable to tethered systems (86%). Most respondents indicated that oxygen saturation (93%), heart rate (80%), and blood pressure (71%) should be continuously monitored with wrist devices (71%) or skin adhesive patches (54%). They believed it may help detect clinical deterioration earlier (90%), decrease rescue interventions (59%), and decrease hospital mortality (54%). Opinions diverged regarding the impact on nurse workload (increase 46%, decrease 39%), and most respondents considered that the biggest implementation challenges are economic (79%) and connectivity issues (64%). Conclusion: Continuous monitoring of vital signs with wireless sensors is wanted by most anaesthesiologists from university hospitals in Western Europe and in the USA. They believe it may improve patient safety and outcome, but may also be challenging to implement because of cost and connectivity issues.

Impact of conventional vs. goal-directed fluid therapy on urethral tissue perfusion in patients undergoing liver surgery: A pilot randomised controlled trial.

BACKGROUND: Although fluid administration is a key strategy to optimise haemodynamic status and tissue perfusion, optimal fluid administration during liver surgery remains controversial. OBJECTIVE: To test the hypothesis that a goal-directed fluid therapy (GDFT) strategy, when compared with a conventional fluid strategy, would better optimise systemic blood flow and lead to improved urethral tissue perfusion (a new variable to assess peripheral blood flow), without increasing blood loss. DESIGN: Single-centre prospective randomised controlled superiority study. SETTING: Erasme Hospital. PATIENTS: Patients undergoing liver surgery. INTERVENTION: Forty patients were randomised into two groups: all received a basal crystalloid infusion (maximum 2 ml kg-1 h-1). In the conventional fluid group, the goal was to maintain central venous pressure (CVP) as low as possible during the dissection phase by giving minimal additional fluid, while in the posttransection phase, anaesthetists were free to compensate for any presumed fluid deficit. In the GDFT group, patients received in addition to the basal infusion, multiple minifluid challenges of crystalloid to maintain stroke volume (SV) variation less than 13%. Noradrenaline infusion was titrated to keep mean arterial pressure more than 65 mmHg in all patients. MAIN OUTCOME MEASURE: The mean intra-operative urethral perfusion index. RESULTS: The mean urethral perfusion index was significantly higher in the GDFT group than in the conventional fluid group (8.70 [5.72 to 13.10] vs. 6.05 [4.95 to 8.75], P = 0.046). SV index (ml m-2) and cardiac index (l min-1 m-2) were higher in the GDFT group (48 ±â€Š9 vs. 33 ±â€Š7 and 3.5 ±â€Š0.7 vs. 2.4 ±â€Š0.4, respectively; P < 0.001). Although CVP was higher in the GDFT group (9.3 ±â€Š2.5 vs. 6.5 ±â€Š2.9 mmHg; P = 0.003), intra-operative blood loss was not significantly different in the two groups. CONCLUSION: In patients undergoing liver surgery, a GDFT strategy resulted in a higher mean urethral perfusion index than did a conventional fluid strategy and did not increase blood loss despite higher CVP. TRIAL REGISTRATION: NCT04092608.

Shedding light on perioperative hemodynamic monitoring.

Given the number of clinical studies and meta-analyses investigating the impact of cardiac output-guided hemodynamic management on the postoperative outcome of patients undergoing high-risk surgery, clinicians should already have a fair idea of the clinical and economic benefits. However, this is still a matter of debate, there are still large outcome studies going on, and surveys and audits have shown that clinical adoption remains low. Rational patient selection, more affordable monitoring solutions, and the personalization of therapeutic strategies are desirable to ensure that cardiac output monitoring adds value and becomes part of the routine anesthesia management of high-risk surgical patients.

Perioperative hemodynamic management 4.0.

Postoperative complications within 30 days represent the third leading cause of death in the world. Multiple solutions have been proposed to tackle the clinical and economic burden of postoperative complications. They include the optimal fluid and hemodynamic management of patients undergoing major surgery. Technological innovations and a better understanding of cardiovascular physiology underlie the evolution of perioperative hemodynamic management, ranging from the mere normalization of heart rate, blood pressure, and central venous pressure to oxygen delivery maximization with a pulmonary artery catheter and individualized fluid management with esophageal Doppler or pulse contour methods. The concept of personalized hemodynamic management recently emerged and may soon become a reality, because of new technologies enabling noninvasive measurement of cardiac output, not only during and after but also before surgery. The monitoring of microcirculation and tissue perfusion may help to fine tune this approach. Importantly, mortality within 30 days after surgery is 1000 times higher than intraoperative mortality. Therefore, continuous ward monitoring with wireless and wearable sensors may be the next major opportunity to improve patient safety.

Perioperative Quality Initiative consensus statement on postoperative blood pressure, risk and outcomes for elective surgery.

BACKGROUND: Postoperative hypotension and hypertension are frequent events associated with increased risk of adverse outcomes. However, proper assessment and management is often poorly understood. As a part of the PeriOperative Quality Improvement (POQI) 3 workgroup meeting, we developed a consensus document addressing this topic. The target population includes adult, non-cardiac surgical patients in the postoperative phase outside of the ICU. METHODS: A modified Delphi technique was used, evaluating papers published in MEDLINE examining postoperative blood pressure monitoring, management, and outcomes. Practice recommendations were developed in line with National Institute for Health and Care Excellence guidelines. RESULTS: Consensus recommendations were that (i) there is evidence of harm associated with postoperative systolic arterial pressure <90 mm Hg; (ii) for patients with preoperative hypertension, the threshold at which harm occurs may be higher than a systolic arterial pressure of 90 mm Hg; (iii) there is insufficient evidence to precisely define the level of postoperative hypertension above which harm will occur; (iv) a greater frequency of postoperative blood pressure measurement is likely to identify risk of harm and clinical deterioration earlier; and (v) there is evidence of harm from withholding beta-blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors in the postoperative period. CONCLUSIONS: Despite evidence of associations with postoperative hypotension or hypertension with worse postoperative outcome, further research is needed to define the optimal levels at which intervention is beneficial, to identify the best methods and timing of postoperative blood pressure measurement, and to refine the management of long-term antihypertensive treatment in the postoperative phase.

Outcome impact of hemodynamic and depth of anesthesia monitoring during major cancer surgery: a before-after study.

Hemodynamic and depth of anesthesia (DOA) monitoring are used in many high-risk surgical patients without well-defined indications and objectives. We implemented monitoring guidelines to rationalize hemodynamic and anesthesia management during major cancer surgery. In early 2014, we developed guidelines with specific targets (Mean arterial pressure > 65 mmHg, stroke volume variation < 12%, cardiac index > 2.5 l min-1 m-2, central venous oxygen saturation > 70%, 40 < bispectral index < 60) for open abdominal cancer surgeries > 2 h. Pre-, intra-, and post-operative data were collected from our electronic medical record database and compared before (March-August 2013) and after (March-August 2014) guideline implementation. A total of 596 patients were studied, 313 before (Before group) and 283 after (After group) guideline implementation. The two groups were comparable for age, ASA score, physiological P-POSSUM score, and surgery duration, but the operative P-POSSUM score was higher in the after group (20 vs. 18, p = 0.009). The use of cardiac output, central venous oxygen saturation and DOA monitoring increased from 40 to 61%, 20 to 29%, and 60 to 88%, respectively (all p-values < 0.05). Intraoperative fluid volumes decreased (16.0 vs. 14.5 ml kg-1 h-1, p = 0.002), whereas the use of inotropes increased (6 vs. 11%, p = 0.022). Postoperative delirium (16 vs. 8%, p = 0.005), urinary tract infections (6 vs. 2%, p = 0.012) and median hospital length of stay (9.6 vs. 8.8 days, p = 0.032) decreased. In patients undergoing major open abdominal surgery for cancer, despite an increase in surgical risk, the implementation of guidelines with predefined targets for hemodynamic and DOA monitoring was associated with a significant improvement in postoperative outcome.

Smartphones and e-tablets in perioperative medicine.

Smartphones and electronic tablets (e-tablets) have become ubiquitous devices. Their ease of use, smartness, accessibility, mobility and connectivity create unique opportunities to improve quality of surgical care from prehabilitation to rehabilitation. Before surgery, digital applications (Apps), serious games and text messaging may help for a better control of risk factors (hypertension, overweight), for smoking cessation, and for optimizing adherence to preoperative recommendations (e.g., regarding anticoagulation or antihypertensive treatments). During surgery, Apps may help to rationalize fluid management and estimate blood loss. After surgery, smartphones and/or connected sensors (pulse oximeter, adhesive path, electronic tattoo, bioimpedance necklace) can be used to monitor body temperature, heart rate, heart rate variability (detection of cardiac arrhythmia), respiratory rate, arterial oxygen saturation and thoracic fluid content. Therefore, these tools have potential for the early detection of infectious, cardiac and respiratory complications in the wards and from home. When connected to echo probes, smartphones and e-tablets can also be used as ultrasound devices during central venous catheter insertion, for peripheral nerve blocks, and to perform echocardiography in patients developing cardiac complications. Finally, electronic checklists now exist as Apps to enhance communication between patients and healthcare professionals, and to track and record step by step each element of the surgical journey. Studies are now urgently needed to investigate whether this digital revolution can translate into a better outcome, an earlier detection of postoperative complications, a decrease in hospital readmissions and in health care costs.

A sneak peek into digital innovations and wearable sensors for cardiac monitoring.

Many mobile phone or tablet applications have been designed to control cardiovascular risk factors (obesity, smoking, sedentary lifestyle, diabetes and hypertension) or to optimize treatment adherence. Some have been shown to be useful but the long-term benefits remain to be demonstrated. Digital stethoscopes make easier the interpretation of abnormal heart sounds, and the development of pocket-sized echo machines may quickly and significantly expand the use of ultrasounds. Daily home monitoring of pulmonary artery pressures with wireless implantable sensors has been shown to be associated with a significant decrease in hospital readmissions for heart failure. There are more and more non-invasive, wireless, and wearable sensors designed to monitor heart rate, heart rate variability, respiratory rate, arterial oxygen saturation, and thoracic fluid content. They have the potential to change the way we monitor and treat patients with cardiovascular diseases in the hospital and beyond. Some may have the ability to improve quality of care, decrease the number of medical visits and hospitalization, and ultimately health care costs. Validation and outcome studies are needed to clarify, among the growing number of digital innovations and wearable sensors, which tools have real clinical value.

Potential return on investment for implementation of perioperative goal-directed fluid therapy in major surgery: a nationwide database study.

BACKGROUND: Preventable postsurgical complications are increasingly recognized as a major clinical and economic burden. A recent meta-analysis showed a 17-29 % decrease in postoperative morbidity with goal-directed fluid therapy. Our objective was to estimate the potential economic impact of perioperative goal-directed fluid therapy. METHODS: We studied 204,680 adult patients from 541 US hospitals who had a major non-cardiac surgical procedure between January 2011 and June 2013. Hospital costs (including 30-day readmission costs) in patients with and without complications were extracted from the Premier Inc. research database, and potential cost-savings associated with a 17-29 % decrease in postoperative morbidity were estimated. RESULTS: A total of 76,807 patients developed one or more postsurgical complications (morbidity rate 37.5 %). In patients with and without complications, hospital costs were US$27,607 ± 32,788 and US$15,783 ± 12,282 (p < 0.0001), respectively. Morbidity rate was anticipated to decrease to 26.6-31.1 % with goal-directed fluid therapy, yielding potential gross cost-savings of US$153-263 million for the study period, US$61-105 million per year, or US$754-1286 per patient. Potential savings per patient were highly variable from one surgical procedure to the other, ranging from US$354-604 for femur and hip-fracture repair to US$3515-5996 for esophagectomies. When taking into account the volume of procedures, the total potential savings per year were the most significant (US$32-55 million) for colectomies. CONCLUSIONS: Postsurgical complications occurred in more than one third of our study population and had a dramatic impact on hospital costs. With goal-directed fluid therapy, potential cost-savings per patient were US$754-1286. The highest cost-savings per year were observed for colectomies. These projections should help hospitals estimate the return on investment when considering the implementation of goal-directed fluid therapy.

Tackling the economic burden of postsurgical complications: would perioperative goal-directed fluid therapy help?

INTRODUCTION: Pay-for-performance programs and economic constraints call for solutions to improve the quality of health care without increasing costs. Many studies have shown decreased morbidity in major surgery when perioperative goal directed fluid therapy (GDFT) is used. We assessed the clinical and economic burden of postsurgical complications in the University HealthSystem Consortium (UHC) in order to predict potential savings with GDFT. METHODS: Data from adults who had a major surgical procedure in 2011 were screened in the UHC database. Thirteen post-surgical complications were tabulated. In-hospital mortality, hospital length of stay and costs from patients with and without complications were compared. The risk ratios reported by the most recent meta-analysis were used to estimate the potential reduction in post-surgical morbidity with GDFT. Potential cost-savings were calculated from the actual and anticipated morbidity rates. RESULTS: A total of 75,140 patients met the search criteria, and 8,421 patients developed one or more post-surgical complications (morbidity rate 11.2%). In patients with and without complications, in-hospital mortality was 12.4% and 1.4% (P <0.001), mean hospital length of stay was 20.5 ± 20.1 days and 8.1 ± 7.1 days (P <0.001) and mean direct costs were $47,284 ± 49,170 and $17,408 ± 15,612 (P < 0.001), respectively. With GDFT, morbidity rate was projected to decrease to 8.0 - 9.3%, yielding gross costs savings of $43 M - $73 M for the study population or $569 - $970 per patient. CONCLUSION: Postsurgical complications have a dramatic impact (+172%) on costs. Potential costs savings resulting from GDFT are substantial. Perioperative GDFT may be recommended not only to improve quality of care but also to decrease costs.

Online monitoring of pulse pressure variation to guide fluid therapy after cardiac surgery.

BACKGROUND: The arterial pulse pressure variation induced by mechanical ventilation (deltaPP) has been shown to be a predictor of fluid responsiveness. Until now, deltaPP has had to be calculated offline (from a computer recording or a paper printing of the arterial pressure curve), or to be derived from specific cardiac output monitors, limiting the widespread use of this parameter. Recently, a method has been developed for the automatic calculation and real-time monitoring of deltaPP using standard bedside monitors. Whether this method is to predict reliable predictor of fluid responsiveness remains to be determined. METHODS: We conducted a prospective clinical study in 59 mechanically ventilated patients in the postoperative period of cardiac surgery. Patients studied were considered at low risk for complications related to fluid administration (pulmonary artery occlusion pressure < 20 mm Hg, left ventricular ejection fraction > or = 40%). All patients were instrumented with an arterial line and a pulmonary artery catheter. Cardiac filling pressures and cardiac output were measured before and after intravascular fluid administration (20 mL/kg of lactated Ringer's solution over 20 min), whereas deltaPP was automatically calculated and continuously monitored. RESULTS: Fluid administration increased cardiac output by at least 15% in 39 patients (66% = responders). Before fluid administration, responders and nonresponders were comparable with regard to right atrial and pulmonary artery occlusion pressures. In contrast, deltaPP was significantly greater in responders than in nonresponders (17% +/- 3% vs 9% +/- 2%, P < 0.001). The deltaPP cut-off value of 12% allowed identification of responders with a sensitivity of 97% and a specificity of 95%. CONCLUSION: Automatic real-time monitoring of deltaPP is possible using a standard bedside monitor and was found to be a reliable method to predict fluid responsiveness after cardiac surgery. Additional studies are needed to determine if this technique can be used to avoid the complications of fluid administration in high-risk patients.

Goal-directed fluid management based on pulse pressure variation monitoring during high-risk surgery: a pilot randomized controlled trial.

INTRODUCTION: Several studies have shown that maximizing stroke volume (or increasing it until a plateau is reached) by volume loading during high-risk surgery may improve post-operative outcome. This goal could be achieved simply by minimizing the variation in arterial pulse pressure (deltaPP) induced by mechanical ventilation. We tested this hypothesis in a prospective, randomized, single-centre study. The primary endpoint was the length of postoperative stay in hospital. METHODS: Thirty-three patients undergoing high-risk surgery were randomized either to a control group (group C, n = 16) or to an intervention group (group I, n = 17). In group I, deltaPP was continuously monitored during surgery by a multiparameter bedside monitor and minimized to 10% or less by volume loading. RESULTS: Both groups were comparable in terms of demographic data, American Society of Anesthesiology score, type, and duration of surgery. During surgery, group I received more fluid than group C (4,618 +/- 1,557 versus 1,694 +/- 705 ml (mean +/- SD), P < 0.0001), and deltaPP decreased from 22 +/- 75 to 9 +/- 1% (P < 0.05) in group I. The median duration of postoperative stay in hospital (7 versus 17 days, P < 0.01) was lower in group I than in group C. The number of postoperative complications per patient (1.4 +/- 2.1 versus 3.9 +/- 2.8, P < 0.05), as well as the median duration of mechanical ventilation (1 versus 5 days, P < 0.05) and stay in the intensive care unit (3 versus 9 days, P < 0.01) was also lower in group I. CONCLUSION: Monitoring and minimizing deltaPP by volume loading during high-risk surgery improves postoperative outcome and decreases the length of stay in hospital. TRIAL REGISTRATION: NCT00479011.