Comparison of a continuous noninvasive arterial pressure device with invasive measurements in cardiovascular postsurgical intensive care patients: a prospective observational study

Evolutionary trends and innovations in cardiovascular intervention

Cardiovascular diseases remain a global health challenge, prompting continuous innovation in medical technology, particularly in Cardiovascular MedTech. This article provides a comprehensive exploration of the transformative landscape of Cardiovascular MedTech in the 21st century, focusing on interventions. The escalating prevalence of cardiovascular diseases and the demand for personalized care drive the evolving landscape, with technologies like wearables and AI reshaping patient-centric healthcare. Wearable devices offer real-time monitoring, enhancing procedural precision and patient outcomes. AI facilitates risk assessment and personalized treatment strategies, revolutionizing intervention precision. Minimally invasive procedures, aided by robotics and novel materials, minimize patient impact and improve outcomes. 3D printing enables patient-specific implants, while regenerative medicine promises cardiac regeneration. Augmented reality headsets empower surgeons during procedures, enhancing precision and awareness. Novel materials and radiation reduction techniques further optimize interventions, prioritizing patient safety. Data security measures ensure patient privacy in the era of connected healthcare. Modern technologies enhance traditional surgeries, refining outcomes. The integration of these innovations promises to shape a healthier future for cardiovascular procedures, emphasizing collaboration and research to maximize their transformative potential.

Risk factors for poor performance in finger cuff non-invasive monitoring of arterial pressure: A prospective multicenter study

BACKGROUND

Compared to the invasive technique, non-invasive monitoring of arterial pressure favors easier and faster implementation while potentially sacrificing some reliability. This may be particularly true for the Clearsight™ system (Edwards Lifesciences), which enables continuous monitoring. We evaluated the risk factors for its poor performance.

METHODS

Patients with an arterial catheter and stable mean arterial pressure (MAP) over a 5-min period were included. Six pairs of invasive and Clearsight measurements of MAP were collected and the bias between the two techniques was calculated. Poor performance of the Clearsight™ system was defined as either a failure to measure and display MAP or displaying an erroneous MAP (individual bias > 5 mmHg). Fingertip perfusion was assessed using the plethysmographic perfusion index (PI) and the capillary refill time (CRT).

RESULTS

Among 152 ICU patients (MAP of 81 ± 14 mmHg, norepinephrine in 78 [51%]), 78 (51%) experienced a poor performance of the Clearsight™ system: failure to display MAP in 19 (13%) patients, and erroneous value displayed in 59 (44%). In multivariate analysis, PI ≤ 0.85% (adjusted odds ratio [aOR] = 2.94 [95% confidence interval (95%CI):1.34;6.45]), CRT > 4 s (aOR = 5.28 [95%CI 1.39;20.05]), and the presence of hand edema (aOR = 2.06 [95%CI 1.01;4.21]) were associated with a higher likelihood of poor performance. Cardiac arrhythmia (aOR = 1.39 [95%CI 0.64;3.02]) and other tested variables were not associated with poor performance.

CONCLUSIONS

Half of the included patients exhibited poor Clearsight™ system performance. Our results caution against using finger cuff arterial pressure monitoring in patients with low PI (≤0.85%), protracted CRT (>4 s), or hand edema.

REGISTRATION

ClinicalTrials.gov, NCT04269382, Dr. G. Muller, February 13, 2020. https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04269382.

Continuous vs intermittent Non-Invasive blood pressure MONitoring in preventing postoperative organ failure (niMON): study protocol for an open-label, multicenter randomized trial

BACKGROUND

Blood pressure has become one of the most important vital signs to monitor in the perioperative setting. Recently, the Italian Society of Anesthesia Analgesia Resuscitation and Intensive Care (SIAARTI) recommended, with low level of evidence, continuous monitoring of blood pressure during the intraoperative period. Continuous monitoring allows for early detection of hypotension, which may potentially lead to a timely treatment. Whether the ability to detect more hypotension events by continuous noninvasive blood pressure (C-NiBP) monitoring can improve patient outcomes is still unclear. Here, we report the rationale, study design, and statistical analysis plan of the niMON trial, which aims to evaluate the effect of intraoperative C-NiBP compared with intermittent (I-NiBP) monitoring on postoperative myocardial and renal injury.

METHODS

The niMon trial is an investigator-initiated, multicenter, international, open-label, parallel-group, randomized clinical trial. Eligible patients will be randomized in a 1:1 ratio to receive C-NiBP or I-NiBP as an intraoperative monitoring strategy. The proportion of patients who develop myocardial injury in the first postoperative week is the primary outcome; the secondary outcomes are the proportions of patients who develop postoperative AKI, in-hospital mortality rate, and 30 and 90 postoperative days events. A sample size of 1265 patients will provide a power of 80% to detect a 4% absolute reduction in the rate of the primary outcome.

CONCLUSIONS

The niMON data will provide evidence to guide the choice of the most appropriate intraoperative blood pressure monitoring strategy.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registration: NCT05496322, registered on the 5th of August 2023.

Detection of impending reflex syncope by means of an integrated multisensor patch-type recorder

We assessed the capability of an integrated multisensory patch-type monitor (RootiRx®) in detecting episodes of reflex (pre)syncope induced by tilt table test (TTT). Firstly, we performed an intrapatient comparison of cuffless systolic blood pressure (SBP), R-R interval (RRI) and variability (power spectrum analysis) obtained by means of the RootiRx® with those obtained with conventional methods (CONV) with validated finger pressure devices at baseline in supine position and repeatedly during TTT in 32 patients affected by likely reflex syncope. Secondly, the LF/HF values obtained with RootiRx® during TTT were analyzed in 50 syncope patients. Compared with baseline supine recordings, during TTT a decrement of median SBP was observed with CONV (-53.5 mmHg) but not with RootiRx® ®(-1 mmHg). Conversely, RRI reduction (CONV: 102 ms; RootiRx®: 127 ms) and RRI Low Frequency/High Frequency powers ratio (LF/HF) increase (CONV: 1.6; RootiRx®: 2.5) were similar. The concordance was good for RRI (0.97 [95% CI 0.96-0.98]) and fair for LF/HF ratio (0.69 [95% CI 0.46-0.83]). During the first 5 min of TTT the LF/HF ratio was higher in patients who later developed syncope than in no-syncope patients. This ratio was significantly different among patients with syncope, presyncope or without symptoms at the time of syncope (p value = 0.02). In conclusion, cuffless RootiRx® was unable to detect rapid drops of SBP occurring during impending reflex syncope and thus cannot be used as a diagnostic tool for hypotensive syncope. On the other hand, RRI mean values and LF/HF power ratios obtained with RootiRx® were consistent with those simultaneously obtained using conventional methods.

Prediction of episode of hemodynamic instability using an electrocardiogram based analytic: a retrospective cohort study

BACKGROUND

Predicting the onset of hemodynamic instability before it occurs remains a sought-after goal in acute and critical care medicine. Technologies that allow for this may assist clinicians in preventing episodes of hemodynamic instability (EHI). We tested a novel noninvasive technology, the Analytic for Hemodynamic Instability-Predictive Indicator (AHI-PI), which analyzes a single lead of electrocardiogram (ECG) and extracts heart rate variability and morphologic waveform features to predict an EHI prior to its occurrence.

METHODS

Retrospective cohort study at a quaternary care academic health system using data from hospitalized adult patients between August 2019 and April 2020 undergoing continuous ECG monitoring with intermittent noninvasive blood pressure (NIBP) or with continuous intraarterial pressure (IAP) monitoring.

RESULTS

AHI-PI's low and high-risk indications were compared with the presence of EHI in the future as indicated by vital signs (heart rate > 100 beats/min with a systolic blood pressure < 90 mmHg or a mean arterial blood pressure of < 70 mmHg). 4,633 patients were analyzed (3,961 undergoing NIBP monitoring, 672 with continuous IAP monitoring). 692 patients had an EHI (380 undergoing NIBP, 312 undergoing IAP). For IAP patients, the sensitivity and specificity of AHI-PI to predict EHI was 89.7% and 78.3% with a positive and negative predictive value of 33.7% and 98.4% respectively. For NIBP patients, AHI-PI had a sensitivity and specificity of 86.3% and 80.5% with a positive and negative predictive value of 11.7% and 99.5% respectively. Both groups performed with an AUC of 0.87. AHI-PI predicted EHI in both groups with a median lead time of 1.1 h (average lead time of 3.7 h for IAP group, 2.9 h for NIBP group).

CONCLUSIONS

AHI-PI predicted EHIs with high sensitivity and specificity and within clinically significant time windows that may allow for intervention. Performance was similar in patients undergoing NIBP and IAP monitoring.

Energy Expenditure Under General Anesthesia: An Observational Study Using Indirect Calorimetry in Patients Having Noncardiac Surgery

BACKGROUND

Perioperative hemodynamic management aims to optimize organ perfusion pressure and blood flow-assuming this ensures that oxygen delivery meets cellular metabolic needs. Cellular metabolic needs are reflected by energy expenditure. A better understanding of energy expenditure under general anesthesia could help tailor perioperative hemodynamic management to actual demands. We thus sought to assess energy expenditure under general anesthesia. Our primary hypothesis was that energy expenditure under general anesthesia is lower than preoperative awake resting energy expenditure.

METHODS

We conducted an observational study on patients having elective noncardiac surgery at the University Medical Center Hamburg-Eppendorf (Germany) between September 2019 and March 2020. We assessed preoperative awake resting energy expenditure, energy expenditure under general anesthesia, and energy expenditure after surgery using indirect calorimetry. We compared energy expenditure under general anesthesia at incision to preoperative awake resting energy expenditure using a Wilcoxon signed-rank test for paired measurements.

RESULTS

We analyzed 60 patients. Median (95% confidence interval [CI]) preoperative awake resting energy expenditure was 953 (95% CI, 906-962) kcal d -1 m -2 . Median energy expenditure under general anesthesia was 680 (95% CI, 642-711) kcal d -1 m -2 -and thus 263 (95% CI, 223-307) kcal d -1 m -2 or 27% (95% CI, 23%-30%) lower than preoperative awake resting energy expenditure ( P < .001).

CONCLUSIONS

Median energy expenditure under general anesthesia is about one-quarter lower than preoperative awake resting energy expenditure in patients having noncardiac surgery.

Insular Role in Blood Pressure and Systemic Vascular Resistance Regulation

OBJECTIVES

The insula is a brain area involved in the modulation of autonomic responses. Previous studies have focused mainly on its heart rate regulatory function, but its role in vascular control is not well defined. Ictal/postictal blood pressure (BP) fluctuations may have a role in the pathogenesis of sudden unexpected death in epilepsy. This study aims to characterize the insular influence on vascular regulation through direct high-frequency electrical stimulation (E-stim) of different insular regions during stereo-electroencephalographic studies.

MATERIALS AND METHODS

An observational, prospective study was conducted, involving people with epilepsy who underwent E-stim of depth electrodes implanted in the insular cortex. Patients with anatomical or electrophysiological insular abnormalities, E-stim producing after discharges, or any elicited symptoms were excluded. Variations of BP and systemic vascular resistance (SVR) during the insular stimuli were analyzed, comparing them with those observed during E-stim of control contacts implanted in cortical noneloquent regions and sham stimulations.

RESULTS

Fourteen patients were included, five implanted in the right insula and nine in the left. We analyzed 14 stimulations in the right insula, 18 in the left insula, 18 in control electrodes, and 13 sham stimulations. Most right insular responses were hypertensive, whereas most left ones were hypotensive. E-stim of the right insula produced a significant BP and SVR increase, whereas the left insula induced a significant BP decrease without SVR changes. The most remarkable changes were elicited in both posterior insulas, although the magnitude of BP changes was generally low. Control and sham stimulations did not induce BP or SVR changes.

CONCLUSION

Our findings on insular stimulation suggest an interhemispheric difference in its vascular regulatory function, with a vasopressor effect of the right insula and a vasodilator effect of the left one.

The consistency of invasive and non-invasive arterial blood pressure for the assessment of dynamic cerebral autoregulation in NICU patients

Background

Studies of the clinical application of dynamic cerebral autoregulation show considerable variations, and differences in blood pressure devices may be one of the reasons for this variation. Few studies have examined the consistency of invasive and non-invasive arterial blood pressure for evaluating cerebral autoregulation. We attempted to investigate the agreement between invasive and non-invasive blood pressure methods in the assessment of dynamic cerebral autoregulation with transfer function analysis.

Methods

Continuous cerebral blood flow velocity and continuous invasive and non-invasive arterial blood pressure were simultaneously recorded for 15 min. Transfer function analysis was applied to derive the phase shift, gain and coherence function at all frequency bands from the first 5, 10, and 15 min of the 15-min recordings. The consistency was assessed with Bland-Altman analysis and intraclass correlation coefficient.

Results

The consistency of invasive and noninvasive blood pressure methods for the assessment of dynamic cerebral autoregulation was poor at 5 min, slightly improved at 10 min, and good at 15 min. The values of the phase shift at the low-frequency band measured by the non-invasive device were higher than those measured with invasive equipment. The coherence function values measured by the invasive technique were higher than the values derived from the non-invasive method.

Conclusion

Both invasive and non-invasive arterial blood pressure methods have good agreement in evaluating dynamic cerebral autoregulation when the recording duration reaches 15 min. The phase shift values measured with non-invasive techniques are higher than those measured with invasive devices. We recommend selecting the most appropriate blood pressure device to measure cerebral autoregulation based on the disease, purpose, and design.

Feasibility of Blood Pressure Measurement With a Wearable (Watch-Type) Monitor During Impending Syncopal Episodes

Background

We assessed the reliability and feasibility of blood pressure (BP) measurements by means of a new wearable watch‐type BP monitor (HeartGuide) in detecting episodes of hypotensive (pre)syncope induced by tilt table test.

Methods and Results

An intrapatient comparison between systolic BP (SBP) measured by means of the HeartGuide device and noninvasive finger beat‐to‐beat BP monitoring was undertaken both at baseline in supine position and repeatedly during tilt table test in patients evaluated for reflex syncope. Intrapatient fall of systolic BP from baseline was measured. Eighty‐one patients (mean age, 61±19 years; 46 women) were included. Overall, HeartGuide was able to yield BP values at the time of BP nadir in 58 (72%) patients (average HeartGuide SBP 102±18 mm Hg, versus finger SBP 101±19 mm Hg). Compared with baseline, the maximum SBP decrease was on average −28.5±27.8 and −30.3±33.9 mm Hg respectively (Lin's concordance correlation coefficient=0.78, r=0.79, P=0.001). In the subgroup of 38 patients with tilt table test induced (pre)syncope, the average HeartGuide SBP during symptoms was 97±16 mm Hg, and the finger SBP was 94±18 mm Hg. Compared with baseline, the maximum SBP decrease was on average −35.2±29.3 and −43.3±31.8 mm Hg, respectively (Lin's concordance correlation coefficient=0.83, r=0.87, P=0.001).

Conclusions

Our data indicate that the HeartGuide BP monitor can detect low BP during presyncope and that its measure of SBP change is consistent with that simultaneously obtained through continuous BP monitoring, despite some intrapatient variability. Thus, this device might be useful in determining the hypotensive nature of spontaneous (pre)syncopal symptoms, a possibility that should be verified by field studies.

Detection of Hemodynamic Status Using an Analytic Based on an Electrocardiogram Lead Waveform

OBJECTIVES

Delayed identification of hemodynamic deterioration remains a persistent issue for in-hospital patient care. Clinicians continue to rely on vital signs associated with tachycardia and hypotension to identify hemodynamically unstable patients. A novel, noninvasive technology, the Analytic for Hemodynamic Instability (AHI), uses only the continuous electrocardiogram (ECG) signal from a typical hospital multiparameter telemetry monitor to monitor hemodynamics. The intent of this study was to determine if AHI is able to predict hemodynamic instability without the need for continuous direct measurement of blood pressure.

DESIGN

Retrospective cohort study.

SETTING

Single quaternary care academic health system in Michigan.

PATIENTS

Hospitalized adult patients between November 2019 and February 2020 undergoing continuous ECG and intra-arterial blood pressure monitoring in an intensive care setting.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One million two hundred fifty-two thousand seven hundred forty-two 5-minute windows of the analytic output were analyzed from 597 consecutive adult patients. AHI outputs were compared with vital sign indications of hemodynamic instability (heart rate > 100 beats/min, systolic blood pressure < 90 mm Hg, and shock index of > 1) in the same window. The observed sensitivity and specificity of AHI were 96.9% and 79.0%, respectively, with an area under the curve (AUC) of 0.90 for heart rate and systolic blood pressure. For the shock index analysis, AHI's sensitivity was 72.0% and specificity was 80.3% with an AUC of 0.81.

CONCLUSIONS

The AHI-derived hemodynamic status appropriately detected the various gold standard indications of hemodynamic instability (hypotension, tachycardia and hypotension, and shock index > 1). AHI may provide continuous dynamic hemodynamic monitoring capabilities in patients who traditionally have intermittent static vital sign measurements.

Continuous Noninvasive Blood Pressure Monitoring of Beat-By-Beat Blood Pressure and Heart Rate Using Caretaker Compared With Invasive Arterial Catheter in the Intensive Care Unit

OBJECTIVE

To examine the accuracy of noninvasively-derived peripheral arterial blood pressure (BP) by the Caretaker device (CT) against invasively measured arterial BP and the fidelity of heart rate variability by CT compared with electrocardiogram (ECG)-derived data.

DESIGN

Prospective cohort study.

PARTICIPANTS

Adult surgical and trauma patients admitted to the intensive care unit.

SETTING

Academic tertiary care medical center.

INTERVENTIONS

In a prospective manner, beat-by-beat BP by CT was recorded simultaneously with invasive arterial BP measured in patients in the intensive care unit. Invasive arterial BPs were compared with those obtained by the CT system. All comparisons among the CT data, arterial catheter data, and ECG data were postprocessed.

MEASUREMENTS AND MAIN RESULTS

From 37 enrolled patients, 34 were included with satisfactory data that overlapped between arterial catheter and CT. A total of 87,757 comparative data points were obtained for the 40-minute time window comparisons of the 34 patients, spanning approximately 22.5 hours in total. Systolic BP and diastolic BP correlations (Pearson coefficient), as well as the mean difference (standard deviation), were 0.92 and -0.36 (7.57) mmHg and 0.83 and -2.11 (6.00) mmHg, respectively. The overall interbeat correlation was 0.99, with the mean difference between interbeats obtained with the arterial BP and the CT of -0.056 ms (6.0).

CONCLUSIONS

This study validated the noninvasive tracking of BP using the CT device, and the pulse decomposition analysis approach is possible within the guidelines of the standard.

Accuracy and precision of continuous non-invasive arterial pressure monitoring in critical care: A systematic review and meta-analysis

OBJECTIVE

To summarize the evidence regarding the accuracy of continuous non-invasive arterial pressure measurements in adult critical care patients.

RESEARCH METHODOLOGY

Medline, EMBASE, and CINAHL were searched for studies that included adult critical care patients reporting the agreement between continuous non-invasive and invasive arterial pressure measurements. The studies were selected and assessed for risk of bias using the Revised Quality Assessment of Diagnostic Accuracy Studies tool by two independent reviewers. The Grading of Recommendations, Assessment, Development and Evaluations approach was used. Pooled estimates of the mean bias and limits of agreement with outer 95% confidence intervals (termed population limits of agreement) were calculated.

RESULTS

Population limits of agreement for systolic blood pressure were wide, spanning from -36.13 mmHg to 28.28 mmHg (18 studies; 785 participants). Accuracy of diastolic blood pressure measurements was highly inconsistent across studies, resulting in imprecise estimates for the population limits of agreement. Population limits of agreement for mean arterial pressure spanned from -39.96 mmHg to 44.36 mmHg (17 studies; 765 participants). The evidence was rated as very low-quality due to very serious concerns about heterogeneity and imprecision.

CONCLUSION

Substantial differences in blood pressure were identified between measurements taken from continuous non-invasive and invasive monitoring devices. Clinicians should consider this broad range of uncertainty if using these devices to inform clinical decision-making in critical care.

Accuracy of noninvasive continuous arterial pressure monitoring using ClearSight during one-lung ventilation

Noninvasive continuous arterial pressure monitoring may be clinically useful in patients who require continuous blood pressure monitoring in situations where arterial catheter placement is limited. Many previous studies on the accuracy of the noninvasive continuous blood pressure monitoring method reported various results. However, there is no research on the effectiveness of noninvasive arterial pressure monitoring during one-lung ventilation. The purpose of this study was to compare arterial blood pressure obtained through invasive method and noninvasive method by using ClearSight during one-lung ventilation.In this retrospective observational study, a total of 26 patients undergoing one-lung ventilation for thoracic surgery at a single institution between March and July 2019 were recruited. All patients in this study were cannulated on their radial artery to measure continuously invasive blood pressures and applied ClearSight on the ipsilateral side of the cannulated arm. We compared and analyzed the agreement and trendability of blood pressure recorded with invasive and noninvasive methods during one-lung ventilation.Blood pressure and pulse rate showed a narrower limit of agreement with a percentage error value of around 30%. In addition, the tracking ability of each measurement could be determined by the concordance rate, all of which were below acceptable limits (92%).In noninvasive arterial blood pressure monitoring using ClearSight, mean blood pressure and pulse rate show acceptable agreement with the invasive method.

Continuous Blood Pressure Estimation From Electrocardiogram and Photoplethysmogram During Arrhythmias

Objective

Continuous blood pressure (BP) provides valuable information for the disease management of patients with arrhythmias. The traditional intra-arterial method is too invasive for routine healthcare settings, whereas cuff-based devices are inferior in reliability and comfortable for long-term BP monitoring during arrhythmias. The study aimed to investigate an indirect method for continuous and cuff-less BP estimation based on electrocardiogram (ECG) and photoplethysmogram (PPG) signals during arrhythmias and to test its reliability for the determination of BP using invasive BP (IBP) as reference.

Methods

Thirty-five clinically stable patients (15 with ventricular arrhythmias and 20 with supraventricular arrhythmias) who had undergone radiofrequency ablation were enrolled in this study. Their ECG, PPG, and femoral arterial IBP signals were simultaneously recorded with a multi-parameter monitoring system. Fifteen features that have the potential ability in indicating beat-to-beat BP changes during arrhythmias were extracted from the ECG and PPG signals. Four machine learning algorithms, decision tree regression (DTR), support vector machine regression (SVR), adaptive boosting regression (AdaboostR), and random forest regression (RFR), were then implemented to develop the BP models.

Results

The results showed that the mean value ± standard deviation of root mean square error for the estimated systolic BP (SBP), diastolic BP (DBP) with the RFR model against the reference in all patients were 5.87 ± 3.13 and 3.52 ± 1.38 mmHg, respectively, which achieved the best performance among all the models. Furthermore, the mean error ± standard deviation of error between the estimated SBP and DBP with the RFR model against the reference in all patients were −0.04 ± 6.11 and 0.11 ± 3.62 mmHg, respectively, which complied with the Association for the Advancement of Medical Instrumentation and the British Hypertension Society (Grade A) standards.

Conclusion

The results indicated that the utilization of ECG and PPG signals has the potential to enable cuff-less and continuous BP estimation in an indirect way for patients with arrhythmias.

Noninvasive continuous arterial pressure monitoring with Clearsight during awake carotid endarterectomy: A prospective observational study

BACKGROUND

Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a less invasive alternative compared with invasive intra-arterial monitoring for awake patients during carotid endarterectomy (CEA) under regional anaesthesia.

OBJECTIVE

We investigated the agreement of blood pressure (BP) recorded with invasive and CNBP methods during awake CEA.

DESIGN

A prospective observational study for assessing agreement with Bland-Altman plots, agreement-tolerability indices (ATI), concordance and interchangeability.

SETTING

Azienda Ospedaliera Universitaria G. Martino, Messina, a University tertiary referral centre in Italy.

PATIENTS

In 30 consecutive patients, we recorded continuously ipsilateral invasive and noninvasive BPs, from 3 min before carotid cross-clamping to 5 min after unclamping.

MAIN OUTCOME MEASURES

Primary outcome was bias, 95% limits of agreement, ATI, concordance and interchangeability for mean arterial pressure (MAP). Secondary outcomes were agreements for systolic arterial pressure and diastolic arterial pressure. Tracking of changes was assessed with four-quadrant polar plots and the trend interchangeability method. Optimal bias was defined as 5 mmHg or less.

RESULTS

A total of 2672 invasive and CNBP paired measurements (93% of overall data) were analysed, with a median of 92 readings per patient [IQR 76 to 100]. Mean (SD) bias for MAP, systolic arterial pressure and DAP were -6.8 (6.7), -3.0 (9.7) and -9.0 (5.4) mmHg, respectively. The ATIs were 0.88, 0.95 and 0.71, respectively, where ATI of 1.0 or less and at least 2.0 defined acceptable, marginal and unacceptable agreements. The four-quadrant plot analysis for beat-to-beat differences showed concordance rates of 97.3%, 99.98% and 96.4%, respectively. Polar plot analysis showed 95% limits of agreement of -3 to 3, -2 to 2 and -2 to 2 mmHg respectively. Trend interchangeability method showed an interchangeability rate of 95% for MAP.

CONCLUSION

During CEA performed under regional anaesthesia, CNBP offers a less invasive approach for BP monitoring. We found acceptable agreement for MAP defined by an ATI of 0.88 and an excellent 95% global interchangeability rate. A suboptimal bias of 7 mmHg was found with CNBP for MAP.

Non-invasive assessment of fluid responsiveness using CNAP™ technology is interchangeable with invasive arterial measurements during major open abdominal surgery

BACKGROUND

Dynamic variables of fluid responsiveness (FR), such as pulse pressure variation (PPV), have been shown to predict the response to a fluid challenge accurately. A recently introduced non-invasive technology based on the volume-clamp method (CNAP™) offers the ability to measure PPV continuously (PPV_CNAP). However, the accuracy regarding the prediction of FR in the operating room has to be proved.

METHODS

We compared PPV_CNAP with an invasive approach measuring PPV using the PiCCO technology (PPV_PiCCO). We studied 47 patients undergoing major open abdominal surgery before and after a passive leg-raising manoeuvre and i.v. fluid resuscitation. A positive response to a volume challenge was defined as ≥15% increase in stroke volume index obtained with transpulmonary thermodilution. Bootstrap methodology was used with the grey zone approach to determine the area of inconsistency regarding the ability of PPV_PiCCO and PPV_CNAP to predict FR.

RESULTS

In response to the passive leg-raising manoeuvre, PPV_PiCCO predicted FR with a sensitivity of 81% and a specificity of 72% [area under the curve (AUC) 0.86] compared with a sensitivity of 76% and a specificity of 72% (AUC 0.78) for PPV_CNAP Regarding the volume challenge in the operating room, PPV_PiCCO predicted FR with a sensitivity of 87% and a specificity of 100% (AUC 0.97) compared with a sensitivity of 91% and specificity of 93% (AUC 0.97) for PPV_CNAP The grey zone approach identified a range of PPV_PiCCO values (11-13%) and PPV_CNAP values (7-11%) for which FR could not be predicted reliably.

CONCLUSIONS

Non-invasive assessment of FR using PPV_CNAP seems to be interchangeable with PPV_PiCCO in patients undergoing major open abdominal surgery.

CLINICAL TRIAL REGISTRATION

NCT02166580.

Efficacy and Safety of Different Norepinephrine Regimens for Prevention of Spinal Hypotension in Cesarean Section: A Randomized Trial

The aim of this paper is to evaluate the efficacy and safety of three different norepinephrine dosing regimens for preventing spinal hypotension in cesarean section. In this randomized double-blinded controlled study, 120 parturients scheduled for elective section delivery under spinal anesthesia were assigned to 1 of 4 groups. In the control group, patients received saline infusion. In three norepinephrine groups, the infusion dosage regimens were 5, 10, and 15 μg/kg/h, respectively. Hypotension was treated with a rescue bolus of 10 μg norepinephrine. The study protocol was continued until the end of surgery. The primary outcome was the proportion of participants that underwent hypotension. The proportion of hypotension participants was significantly reduced in the norepinephrine groups (37.9%, 20%, and 25%, respectively) compared to that in the control group (86.7%). However, the highest dose of norepinephrine (15 μg/kg/h) resulted in more hypertension episodes. In addition, blood pressure was better maintained in the norepinephrine 5 μg/kg/h and 10 μg/kg/h groups than in the control group and 15 μg/kg/h group. No significant differences in other hemodynamic variables, adverse effects, maternal and neonatal blood gases, or Apgar scores were observed among the groups. In summary, for patients who undergo cesarean delivery under spinal anesthesia, infusion of 5–10 μg/kg/h norepinephrine was effective to reduce hypotension incidence without significant adverse effects on maternal and neonatal outcomes. Clinical Trial Registration Number is ChiCTR-INR-16009452.

Improving Perioperative Outcomes Through Minimally Invasive and Non-invasive Hemodynamic Monitoring Techniques

An increasing number of patients require precise intraoperative hemodynamic monitoring due to aging and comorbidities. To prevent undesirable outcomes from intraoperative hypotension or hypoperfusion, appropriate threshold settings are required. These setting can vary widely from patient to patient. Goal-directed therapy techniques allow for flow monitoring as the standard for perioperative fluid management. Based on the concept of personalized medicine, individual assessment and treatment are more advantageous than conventional or uniform interventions. The recent development of minimally and noninvasive monitoring devices make it possible to apply detailed control, tracking, and observation of broad patient populations, all while reducing adverse complications. In this manuscript, we review the monitoring features of each device, together with possible advantages and disadvantages of their use in optimizing patient hemodynamic management.

Noninvasive BP Monitoring in the Critically Ill: Time to Abandon the Arterial Catheter?

Although its reliability is often questioned, noninvasive BP (NIBP)-monitoring with an oscillometric arm cuff is widely used, even in critically ill patients in shock. When correctly implemented, modern arm NIBP devices can provide accurate and precise measurements of mean BP, as well as clinically meaningful information such as identification of hypotension and hypertension and monitoring of patient response to therapy. Even in specific circumstances such as arrhythmia, hypotension, vasopressor infusion, and possibly in obese patients, arm NIBP may be useful, contrary to widespread belief. Hence, postponing the arterial catheter insertion pending the initiation of more urgent diagnostic and therapeutic measures could be a suitable strategy. Given the arterial catheter-related burden, fully managing critically ill patients without any arterial catheter may also be an option. Indeed, the benefit that patients may experience from an arterial catheter has been questioned in studies failing to show that its use reduces mortality. However, randomized controlled trials to confirm that NIBP can safely fully replace the arterial catheter have yet to be performed. In addition to intermittent measurements, continuous NIBP monitoring is a booming field, as illustrated by the release onto the market of user-friendly devices, based on digital volume clamp and applanation tonometry. Although the imperfect accuracy and precision of these devices would probably benefit from technical refinements, their good ability to track, in real time, the direction of changes in BP is an undeniable asset. Their drawbacks and advantages and whether these devices are currently ready to use in the critically ill patient are discussed in this review.

Update on Finger-Application-Type Noninvasive Continuous Hemodynamic Monitors (CNAP and ccNexfin): Physical Principles, Validation, and Clinical Use

The CNAP HD Monitor (CNSystems, Graz, Austria) and the ccNexfin (The ClearSight System: Edwards Lifesciences Corporation, Irvine, CA) are continuous, noninvasive blood pressure monitors using a finger-application device. These devices show a promising ability to allow for rapid detection of hemodynamic derangement when compared with oscillometry. The accuracy and precision of these devices as blood pressure monitors has been evaluated when compared with intra-arterial catheters. Additionally, they can be used to measure beat-to-beat cardiac output (CO). As CO monitors, they are capable of trending changes in CO when compared with a transpulmonary thermodilution monitor. Difficulty with use in critically ill and awake patients has been encountered because of altered microvascular physiology and patient movement. The principles of operation and clinical validation of these devices are presented. The clinicians who are interested in using these devices in their clinical setting should be aware of the relatively large bias and CIs in the hemodynamic measurements.

A Novel Method for Continuous, Noninvasive, Cuff-Less Measurement of Blood Pressure: Evaluation in Patients With Nonalcoholic Fatty Liver Disease

OBJECTIVE

One promising approach for a continuous, noninvasive, cuff-less ambulatory blood pressure (BP) monitor is to measure the pulse wave velocity or the inversely proportional pulse transit time (PTT), based on electrical and optical physiological measurements in the chest area. A device termed IsenseU-BP+ has been developed for measuring continuous BP, as well as other physiological data. The objective of this paper is to present results from the first clinical evaluation with a wide range of patients. The study was set up to verify whether IsenseU-BP+ can be used to measure raw signals with sufficient quality to derive PTT.  Methods: The test protocol, run 23 times on 18 different patients with nonalcoholic fatty liver disease, includes both supine measurement at rest as well as measurements during indoor cycling. Changes in PTT were compared with the BP changes measured using validated reference sensors.  Results: IsenseU-BP+ measured signals with good quality during rest on 17 of 18 patients despite the high diversity in age, body shape, and body mass index. Evaluation during cycling was difficult due to a lack of good reference measurements.

CONCLUSION

IsenseU-BP+ measures PTT with high quality during supine rest and exercise and could therefore be suitable for deriving noninvasive continuous BP, although evaluation during exercise was limited due to inaccurate reference BP measurements.

SIGNIFICANCE

Continuous, noninvasive measurement of BP would be highly beneficial in a number of clinical settings. Systems currently considered as the gold standard for the investigation of hypertension carry considerable limitations, which could be overcome by the method proposed here.

Assessing the eligibility of a non-invasive continuous blood pressure measurement technique for application during total intravenous anaesthesia

OBJECTIVE

To assess the eligibility for replacement of invasive blood pressure as measured "within" the arterial vessel (IBP) with non-invasive continuous arterial blood pressure (cNIP) monitoring during total intravenous anaesthesia (TIVA), the ability of cNiP to track fast blood pressure changes needs to be quantified. A new method of statistical data analysis is developed for this purpose.

METHODS

In a pilot study on patients undergoing neurosurgical anaesthesia, mean arterial pressure MAPIBP measured with IBP was compared to MAPCNP measured by the CNAP Monitor 500 in ten patients (age: 63±13 a). Correlation analysis of changes of device differences ΔeMAP=ΔMAPCNP-ΔMAPIBP with changes of MAPIBP (ΔMAPIBP) during intervals of vasoactivity was conducted. An innovative technique, of linear trend analysis (LTA) applied to two signals, is described to perform this analysis without a priori knowledge of intervals of vasoactivity.

RESULTS

Analysis of ΔeMAP during vasoactivity revealed that ΔMAPCNP systematically underestimated ΔMAPIBP by 37%. This was confirmed in the complete data set using LTA technique showing a systematic, yet patient specific, underestimation in tracking ΔMAPIBP (16…120%).

CONCLUSION

The proposed LTA technique is able to detect systematic errors in tracking short-term blood pressure changes otherwise masked by established analysis. LTA may thus be a useful tool to assess the eligibility of cNIP to replace IBP during TIVA.

Monitoring high-risk patients: minimally invasive and non-invasive possibilities

Over the past decades, there has been considerable progress in the field of less invasive haemodynamic monitoring technologies. Substantial evidence has accumulated, which supports the continuous measurement and optimization of flow-based variables such as stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion and consequently to improve patients' outcome in the perioperative setting. However, there is a striking gap between the developments in haemodynamic monitoring and the increasing evidence to implement defined treatment protocols based on the measured variables, and daily clinical routine. Recent trials have shown that perioperative morbidity and mortality is higher than anticipated. This emphasizes the need for the anaesthesia community to address this issue and promotes the implementation of proven concepts into clinical practice in order to improve patients' outcome, especially in high-risk patients. The advances in minimally invasive and non-invasive monitoring techniques can be seen as a driving force in this respect, as the degree of invasiveness of any monitoring tool determines the frequency of its application, especially in the operating room (OR). From this point of view, we are very confident that some of these minimally invasive and non-invasive haemodynamic monitoring technologies will become an inherent part of our monitoring armamentarium in the OR and in the intensive care unit (ICU).

Advances in photoplethysmography: beyond arterial oxygen saturation

PURPOSE

Photoplethysmography permits continuous measurement of heart rate and peripheral oxygen saturation and has been widely used to inform clinical decisions. Recently, a myriad of noninvasive hemodynamic monitoring devices using this same technology have been increasingly available. This narrative review aims to summarize the principles that form the basis for the function of these devices as well as to comment on trials evaluating their accuracy and clinical application.

PRINCIPAL FINDINGS

Advanced monitoring devices extend photoplethysmography technology beyond measuring oxygen concentration and heart rate. Quantification of respiratory variation of the photoplethysmographic waveform reflects respiratory variation of the arterial pressure waveform and can be used to gauge volume responsiveness. Both the volume-clamp and physiocal techniques are extensions of conventional photoplethysmography and permit continuous measurement of finger arterial blood pressure. Finger arterial pressure waveforms can subsequently inform estimations of cardiac output.

CONCLUSIONS

Although respiratory variations of the plethysmographic waveform correlate only modestly with the arterial blood pressure waveform, fluid responsiveness can be relatively consistently assessed using both approaches. Continuous blood pressure measurements obtained using the volume-clamp technique may be as accurate as conventional brachial noninvasive blood pressure measurements. Most importantly, clinical comparative effectiveness studies are still needed in order to determine if these technologies can be translated into improvement of relevant patient outcomes.

[Goal-directed hemodynamic therapy: Concepts, indications and risks]

Goal-directed hemodynamic therapy is becoming increasingly more interesting for anesthesiologists and intensive care physicians. Meta-analyses of studies evaluating perioperative therapy algorithms demonstrated a reduction of postoperative morbidity compared to the previous clinical practices. In this review article the basic concepts of goal-directed hemodynamic therapy and the principles of previously employed therapy algorithms are described and discussed. Furthermore, the questions of how these therapy strategies can be transferred into daily clinical practice and whether these therapeutic approaches might even bear risks for patients are elucidated.