Changes in Stroke Volume Induced by Lung Recruitment Maneuver Predict Fluid Responsiveness in Mechanically Ventilated Patients in the Operating Room

Stroke volume variation induced by lung recruitment maneuver to predict fluid responsiveness in patients receiving mechanical ventilation: A systematic review and meta-analysis

STUDY OBJECTIVE

The aim of this study was to evaluate the accuracy of lung recruitment maneuver induced stroke volume variation (ΔSVLRM) in predicting fluid responsiveness in mechanically ventilated adult patients by systematic review and meta-analysis.

METHODS

A comprehensive electronic search of relevant literature was conducted in PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase and Chinese databases (including China National Knowledge Infrastructure, Wanfang and VIP databases). Review Manager 5.4, Meta-DiSc 1.4 and STATA 16.0 were selected for data analysis, and QUADAS-2 tool was used for quality assessment. Data from selected studies were pooled to obtain sensitivity, specificity, diagnostic likelihood ratio (DLR) of positive and negative, diagnostic odds ratio (DOR), and summary receiver operating characteristic curve.

RESULTS

A total of 6 studies with 256 patients were enrolled through March 2024. The risk of bias and applicability concerns for each included study were low, and there was no significant publication bias. There was moderate to substantial heterogeneity for the non-threshold effect, but not for the threshold effect. The combined sensitivity and specificity were 0.84 (95% CI, 0.77-0.90) and 0.79 (95% CI, 0.70-0.86), respectively. The DOR and the area under the curve (AUC) were 22.15 (95%CI, 7.62-64.34) and 0.90 (95% CI, 0.87-0.92), respectively. The positive and negative predictive values of DLR were 4.53 (95% CI, 2.50-8.18) and 0.19 (95% CI, 0.11-0.35), respectively. Fagan's nomogram showed that with a pre-test probability of 52%, the post-test probability reached 83% and 17% for the positive and negative tests, respectively.

CONCLUSIONS

Based on the currently available evidence, ΔSVLRM has a good diagnostic value for predicting the fluid responsiveness in adult patients undergoing mechanical ventilation. Given the heterogeneity and limitations of the published data, further studies with large sample sizes and different clinical settings are needed to confirm the diagnostic value of ΔSVLRM in predicting fluid responsiveness. PROSPERO registration number: CRD42023490598.

The Hemodynamic Changes Induced by Lung Recruitment Maneuver to Predict Fluid Responsiveness in Children during One Lung Ventilation-A Prospective Observational Study

BACKGROUND

The prediction of fluid responsiveness in critical patients helps clinicians in decision making to avoid either under- or overloading of fluid. This study was designed to determine whether lung recruitment maneuver (LRM) would have an effect on the predictability of fluid responsiveness by the changes of hemodynamic parameters in pediatric patients who were receiving lung-protective ventilation and one-lung ventilation (OLV).

METHODS

A total of 34 children, aged 1-6 years old, scheduled for heart surgeries via right thoracotomy were enrolled. Patients were anesthetized and OLV with lung-protection ventilation settings was established, and then, positioned on left lateral decubitus. LRM and volume expansion (VE) were performed in sequence. Heart rate (HR), systolic arterial pressure (SAP), mean arterial pressure (MAP) diastolic arterial pressure (DAP), stroke volume (SV), stroke volume variation (SVV), and pulse pressure variation (PPV) were recorded via an A-line based monitor system at the following time points: before and after LRM (T1 and T2) and before and after VE (T3 and T4). An increase in stroke volume (SV) or mean arterial pressure (MAP) of ≥10% following fluid loading identified fluid responders. The predictability of fluid responsiveness by the changes of SV (ΔSVLRM) and MAP (ΔMAPLRM) after LRM and VE were statistically evaluated by receiver operating characteristic curves [area under the curves (AUC)].

RESULTS

SVs in all patients were significantly decreased after LRM (p < 0.01) and then, increased and returned to baseline after VE (p < 0.01). In total, 16 out of 34 patients who were fluid responders had significantly lower SV after LRM compared to that in fluid non-responders. The area under the receiver operating characteristic curves for ΔSVLRM was 0.828 (95% confidence interval [CI], 0.660 to 0.935; p < 0.001) and it indicated that ΔSVLRM was able to predict the fluid responsiveness of pediatric patients. MAPs in all patients were also decreased significantly after LRM, and 12 of them fell into the category of fluid responders after VE. Statistically, ΔMAPLRM did not predict fluid responsiveness when LRM was considered as an influential factor (p = 0.07).

CONCLUSIONS

ΔSVLRM, but not ΔMAPLRM, showed great reliability in the prediction of the fluid responsiveness following VE in children during one-lung ventilation with lung-protective settings.

TRIAL REGISTRATION

ChiCTR2300070690.

Use of stepwise lung recruitment maneuver to predict fluid responsiveness under lung protective ventilation in the operating room

Recent research has revealed that hemodynamic changes caused by lung recruitment maneuvers (LRM) with continuous positive airway pressure can be used to identify fluid responders. We investigated the usefulness of stepwise LRM with increasing positive end-expiratory pressure and constant driving pressure for predicting fluid responsiveness in patients under lung protective ventilation (LPV). Forty-one patients under LPV were enrolled when PPV values were in a priori considered gray zone (4% to 17%). The FloTrac-Vigileo device measured stroke volume variation (SVV) and stroke volume (SV), while the patient monitor measured pulse pressure variation (PPV) before and at the end of stepwise LRM and before and 5 min after fluid challenge (6 ml/kg). Fluid responsiveness was defined as a ≥ 15% increase in the SV or SV index. Seventeen were fluid responders. The areas under the curve for the augmented values of PPV and SVV, as well as the decrease in SV by stepwise LRM to identify fluid responders, were 0.76 (95% confidence interval, 0.61-0.88), 0.78 (0.62-0.89), and 0.69 (0.53-0.82), respectively. The optimal cut-offs for the augmented values of PPV and SVV were > 18% and > 13%, respectively. Stepwise LRM -generated augmented PPV and SVV predicted fluid responsiveness under LPV.

The Effect of Recruitment Maneuver on Static Lung Compliance in Patients Undergoing General Anesthesia for Laparoscopic Cholecystectomy: A Single-Centre Prospective Clinical Intervention Study

Background and Objectives: The aim of this study was to examine whether the use of an alveolar recruitment maneuver (RM) leads to a significant increase in static lung compliance (Cstat) and an improvement in gas exchange in patients undergoing laparoscopic cholecystectomy. Material and Methods: A clinical prospective intervention study was conducted. Patients were divided into two groups according to their body mass index (BMI): normal-weight (group I) and pre-obese and obese grade I (group II). Lung mechanics were monitored (Cstat, dynamic compliance-Cdin, peak pressure-Ppeak, plateau pressure-Pplat, driving pressure-DP) alongside gas exchange, and hemodynamic changes (heart rate-HR, mean arterial pressure-MAP) at six time points: T1 (induction of anesthesia), T2 (formation of pneumoperitoneum), T3 (RM with a PEEP of 5 cm H2O), T4 (RM with a PEEP of 7 cm H2O), T5 (desufflation), and T6 (RM at the end). The RM was performed by increasing the peak pressure by +5 cm of H2O at an equal inspiration-to-expiration ratio (I/E = 1:1) and applying a PEEP of 5 and 7 cm of H2O. Results: Out of 96 patients, 33 belonged to group I and 63 to group II. An increase in Cstat values occurred after all three RMs. At each time point, the Cstat value was measured higher in group I than in group II. A higher increase in Cstat was observed in group II after the second and third RM. Cstat values were higher at the end of the surgical procedure compared to values after the induction of anesthesia. The RM led to a significant increase in PaO2 in both groups without changes in HR or MAP. Conclusions: During laparoscopic cholecystectomy, the application of RM leads to a significant increase in Cstat and an improvement in gas exchange. The prevention of atelectasis during anesthesia should be initiated immediately after the induction of anesthesia, using protective mechanical ventilation and RM.

How to use echocardiography to manage patients with shock?

Echocardiography enables the intensivist to assess the patient with circulatory failure. It allows the clinician to identify rapidly the type and the cause of shock in order to develop an effective management strategy. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied. Early and repeated echocardiography is a valuable tool for the management of shock in the intensive care unit. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. The four core types of shock (cardiogenic, hypovolemic, obstructive, and septic) can readily be identified by echocardiography. Echocardiography can differentiate the different pathologies that may be the cause of each type of shock. More importantly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock, which emphasises on the added value of transthoracic echocardiography (TTE) in such population of patients. In this review we aimed to provide to clinicians a bedside strategy of the use of TTE parameters to manage patients with shock. In the first part of this overview, we detailed the different TTE parameters and how to use them to identify the type of shock. And in the second part, we focused on the use of these parameters to evaluate the effect of treatments, in different types of shock.

Change in stroke volume during alveolar recruitment maneuvers through transient continuous positive airway pressure or stepwise increase in positive end expiratory pressure in anesthetized patients: a prospective randomized double-blind study

PURPOSE

Intraoperative alveolar recruitment maneuvers (ARM) used during protective ventilation strategy may have severe adverse hemodynamic effects, reported mainly during abrupt continuous positive airway pressure (CPAP). Stepwise increase and decrease in positive end expiratory pressure (PEEP) may be used. We compared the hemodynamic effects of these two maneuvers.

METHODS

We enrolled patients scheduled for intermediate to high-risk surgery with continuous arterial pressure and stroke volume (esophageal Doppler) monitoring in a prospective, single-centre, randomized, double-blind study. After induction of anesthesia, we ensured preload independence of stroke volume before an ARM was randomly performed: 30 cm H2O CPAP for 30 sec (CPAP group) or stepwise increase in PEEP from 8 to 20 cm H2O with inspiratory pressure of 10 cm H2O followed by a stepwise decrease in PEEP from 20 to 8 cm H2O (STEP group). The primary outcome was the relative variation in stroke volume.

RESULTS

Thirty-five patients were included in the CPAP and STEP groups. Mean (standard deviation) relative variation in stroke volume was -57 (24)% in the CPAP group and -32 (24)% in the STEP group (difference, -25; 95% confidence interval, -37 to -14; P < 0.001). Changes in systolic, mean, and diastolic arterial pressure over time were not different between groups. The ARM was stopped because of a systolic arterial pressure < 70 mm Hg in four patients in the CPAP group and in one patient in the STEP group.

CONCLUSIONS

Alveolar recruitment maneuvers through stepwise increase and decrease in PEEP have a better hemodynamic tolerance than transient CPAP.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT04802421); first submitted 15 March 2021.

Reliability of pulse pressure and stroke volume variation in assessing fluid responsiveness in the operating room: a metanalysis and a metaregression

BACKGROUND

Pulse pressure and stroke volume variation (PPV and SVV) have been widely used in surgical patients as predictors of fluid challenge (FC) response. Several factors may affect the reliability of these indices in predicting fluid responsiveness, such as the position of the patient, the use of laparoscopy and the opening of the abdomen or the chest, combined FC characteristics, the tidal volume (Vt) and the type of anesthesia.

METHODS

Systematic review and metanalysis of PPV and SVV use in surgical adult patients. The QUADAS-2 scale was used to assess the risk of bias of included studies. We adopted a metanalysis pooling of aggregate data from 5 subgroups of studies with random effects models using the common-effect inverse variance model. The area under the curve (AUC) of pooled receiving operating characteristics (ROC) curves was reported. A metaregression was performed using FC type, volume, and rate as independent variables.

RESULTS

We selected 59 studies enrolling 2,947 patients, with a median of fluid responders of 55% (46-63). The pooled AUC for the PPV was 0.77 (0.73-0.80), with a mean threshold of 10.8 (10.6-11.0). The pooled AUC for the SVV was 0.76 (0.72-0.80), with a mean threshold of 12.1 (11.6-12.7); 19 studies (32.2%) reported the grey zone of PPV or SVV, with a median of 56% (40-62) and 57% (46-83) of patients included, respectively. In the different subgroups, the AUC and the best thresholds ranged from 0.69 and 0.81 and from 6.9 to 11.5% for the PPV, and from 0.73 to 0.79 and 9.9 to 10.8% for the SVV. A high Vt and the choice of colloids positively impacted on PPV performance, especially among patients with closed chest and abdomen, or in prone position.

CONCLUSION

The overall performance of PPV and SVV in operating room in predicting fluid responsiveness is moderate, ranging close to an AUC of 0.80 only some subgroups of surgical patients. The grey zone of these dynamic indices is wide and should be carefully considered during the assessment of fluid responsiveness. A high Vt and the choice of colloids for the FC are factors potentially influencing PPV reliability.

TRIAL REGISTRATION

PROSPERO (CRD42022379120), December 2022. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=379120.

Tidal volume challenge-induced hemodynamic changes can predict fluid responsiveness during one-lung ventilation: an observational study

Background

To evaluate the ability of tidal volume challenge (VTC)-induced hemodynamic changes to predict fluid responsiveness in patients during one-lung ventilation (OLV).

Methods

80 patients scheduled for elective thoracoscopic surgery with OLV were enrolled. The inclusion criteria were: age ≥ 18 years, American Society of Anesthesiologists physical status I-III, normal right ventricular function, normal left ventricular systolic function (ejection fraction ≥55%), and normal or slightly impaired diastolic function. The study protocol was implemented 15 min after starting OLV. Simultaneous recordings were performed for hemodynamic variables of diameter of left ventricular outflow tract, velocity time integral (VTI) of aortic valve, and stroke volume (SV), and ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC were calculated at four time points: with VT 5 mL/kg (T1); after VT increased from 5 mL/kg to 8 mL/kg and maintained at this level for 2 min (T2); after VT was adjusted back to 5 mL/kg for 2 min (T3); and after volume expansion (250 mL of 0.9% saline infused over 10-15 min) (T4). Patients were considered as responders to fluid administration if SV increased by ≥10%. Receiver operating characteristic (ROC) curves for percent decrease in SV, VTI, and MAP by VTC were generated to evaluate their ability to discriminate fluid responders from nonresponders.

Results

Of the 58 patients analyzed, there were 32 responders (55%) and 26 nonresponders (45%). The basic characteristics were comparable between the two groups (p > 0.05). The area under the curve (AUC) for ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC to discriminate responders from nonresponders were 0.81 (95% CI: 0.68-0.90), 0.79 (95% CI: 0.66-0.89), and 0.56 (95% CI: 0.42-0.69). The best threshold for ΔSV-VTC was -16.1% (sensitivity, 78.1%; specificity, 84.6%); the best threshold for ΔVTI-VTC was -14.5% (sensitivity, 78.1%; specificity, 80.8%).

Conclusion

Tidal volume challenge-induced relative change of stroke volume and velocity time integral can predict fluid responsiveness in patients during one-lung ventilation.Clinical Trial Registration: Chinese Clinical Trial Registry, No: chictr210051310.

Diagnostic accuracy of the peripheral venous pressure variation induced by an alveolar recruitment maneuver to predict fluid responsiveness during high-risk abdominal surgery

BACKGROUND

In patients undergoing high-risk surgery, it is recommended to titrate fluid administration using stroke volume or a dynamic variable of fluid responsiveness (FR). However, this strategy usually requires the use of a hemodynamic monitor and/or an arterial catheter. Recently, it has been shown that variations of central venous pressure (ΔCVP) during an alveolar recruitment maneuver (ARM) can predict FR and that there is a correlation between CVP and peripheral venous pressure (PVP). This prospective study tested the hypothesis that variations of PVP (ΔPVP) induced by an ARM could predict FR.

METHODS

We studied 60 consecutive patients scheduled for high-risk abdominal surgery, excluding those with preoperative cardiac arrhythmias or right ventricular dysfunction. All patients had a peripheral venous catheter, a central venous catheter and a radial arterial catheter linked to a pulse contour monitoring device. PVP was always measured via an 18-gauge catheter inserted at the antecubital fossa. Then an ARM consisting of a standardized gas insufflation to reach a plateau of 30 cmH₂O for 30 s was performed before skin incision. Invasive mean arterial pressure (MAP), pulse pressure, heart rate, CVP, PVP, pulse pressure variation (PPV), and stroke volume index (SVI) were recorded before ARM (T1), at the end of ARM (T2), before volume expansion (T3), and one minute after volume expansion (T4). Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed to assess the ability of ∆PVP (index test) to predict FR, defined as an ≥ 10% increase in SVI following the administration of a 4 ml/kg balanced crystalloid solution over 5 min.

RESULTS

∆PVP during ARM predicted FR with an area under the ROC curve of 0.76 (95%CI, 0.63 to 0.86). The optimal threshold determined by the Youden Index was a ∆PVP value of 5 mmHg (95%CI, 4 to 6) with a sensitivity of 66% (95%CI, 47 to 81) and a specificity of 82% (95%CI, 63 to 94). The AUC's for predicting FR were not different between ΔPVP, ΔCVP, and PPV.

CONCLUSION

During high-risk abdominal surgery, ∆PVP induced by an ARM can moderately predict FR. Nevertheless, other hemodynamic variables did not perform better.

Can carotid artery Doppler variations induced by the end-expiratory occlusion maneuver predict fluid responsiveness in septic shock patients?

BACKGROUND

An increase in cardiac index (CI) during an end-expiratory occlusion test (EEOt) predicts fluid responsiveness in ventilated patients. However, if CI monitoring is unavailable or the echocardiographic window is difficult, using the carotid Doppler (CD) could be a feasible alternative to track CI changes. This study investigates whether changes in CD peak velocity (CDPV) and corrected flow time (cFT) during an EEOt were correlated with CI changes and if CDPV and cFT changes predicted fluid responsiveness in patients with septic shock.

METHODS

Prospective, single-center study in adults with hemodynamic instability. The CDPV and cFT on carotid artery Doppler and hemodynamic variables from the pulse contour analysis EV1000™ were recorded at baseline, during a 20-s EEOt, and after fluid challenge (500 mL). We defined responders as those who increased CI ≥ 15% after a fluid challenge.

RESULTS

We performed 44 measurements in 18 mechanically ventilated patients with septic shock and without arrhythmias. The fluid responsiveness rate was 43.2%. The changes in CDPV were significantly correlated with changes in CI during EEOt (r = 0.51 [0.26-0.71]). A significant, albeit lower correlation, was found for cFT (r = 0.35 [0.1-0.58]). An increase in CI ≥ 5.35% during EEOt predicted fluid responsiveness with 78.9% sensitivity and 91.7% specificity, with an area under the ROC curve (AUROC) of 0.85. An increase in CDPV ≥ 10.5% during an EEOt predicted fluid responsiveness with 96.2% specificity and 53.0% sensitivity with an AUROC of 0.74. Sixty-one percent of CDPV measurements (from - 13.5 to 9.5 cm/s) fell within the gray zone. The cFT changes during EEOt did not accurately predict fluid responsiveness.

CONCLUSIONS

In septic shock patients without arrhythmias, an increase in CDPV greater than 10.5% during a 20-s EEOt predicted fluid responsiveness with > 95% specificity. Carotid Doppler combined with EEOt may help optimize preload when invasive hemodynamic monitoring is unavailable. However, the 61% gray zone is a major limitation (retrospectively registered on Clinicaltrials.gov NCT04470856 on July 14, 2020).

Individualizing Fluid Management in Patients with Acute Respiratory Distress Syndrome and with Reduced Lung Tissue Due to Surgery—A Narrative Review

Fluids are the cornerstone of therapy in all critically ill patients. During the last decades, we have made many steps to get fluid therapy personalized and based on individual needs. In patients with lung involvement—acute respiratory distress syndrome—finding the right amount of fluids after lung surgery may be extremely important because lung tissue is one of the most vulnerable to fluid accumulation. In the current narrative review, we focus on the actual perspectives of fluid therapy with the aim of showing the possibilities to tailor the treatment to a patient’s individual needs using fluid responsiveness parameters and other therapeutic modalities.

Prediction of Fluid Responsiveness by the Effect of the Lung Recruitment Maneuver on the Perfusion Index in Mechanically Ventilated Patients During Surgery

Introduction

Excessive or inadequate fluid administration during perioperative period affects outcomes. Adjustment of volume expansion (VE) by performing fluid responsiveness (FR) test plays an important role in optimizing fluid infusion. Since changes in stroke volume (SV) during lung recruitment maneuver (LRM) can predict FR, and peripheral perfusion index (PI) is related to SV; therefore, we hypothesized that the changes in PI during LRM (ΔPILRM) could predict FR during perioperative period.

Methods

Patients who were scheduled for elective non-laparoscopic surgery under general anesthesia with a mechanical ventilator and who required VE (250 mL of crystalloid solution infusion over 10 min) were included. Before VE, LRM was performed by a continuous positive airway pressure of 30 cm H2O for 30 sec; hemodynamic variables with their changes (PI, obtained by pulse oximetry; and ΔPILRM, calculated by using [(PI before LRM—PI after LRM)/PI before LRM]*100) were obtained before and after LRM. After SV (measured by esophageal doppler) and PI had returned to the baseline values, VE was infused, and the values of these variables were recorded again, before and after VE. Fluid responders (Fluid-Res) were defined by an increase in SV ≥10% after VE. Receiver operating characteristic curves of the baseline values and ΔPILRM were constructed and reported as areas under the curve (AUC) with 95% confidence intervals, to predict FR.

Results

Of 32 mechanically ventilated adult patients included, 13 (41%) were in the Fluid-Res group. Before VE and LRM, there were no differences in the mean arterial pressure (MAP), heart rate, SV, and PI between patients in the Fluid-Res and fluid non-responders (Fluid-NonRes) groups. After LRM, SV, MAP, and, PI decreased in both groups, ΔPILRM was greater in the Fluid-Res group than in Fluid-NonRes group (55.2 ± 17.8% vs. 35.3 ± 17.3%, p &lt; 0.001, respectively). After VE, only SV and cardiac index increased in the Fluid-Res group. ΔPILRM had the highest AUC [0.81 (0.66–0.97)] to predict FR with a cut-off value of 40% (sensitivity 92.3%, specificity 73.7%).

Conclusions

ΔPILRM can be applied to predict FR in mechanical ventilated patients during the perioperative period.

Prediction of fluid responsiveness. What’s new?

Although the administration of fluid is the first treatment considered in almost all cases of circulatory failure, this therapeutic option poses two essential problems: the increase in cardiac output induced by a bolus of fluid is inconstant, and the deleterious effects of fluid overload are now clearly demonstrated. This is why many tests and indices have been developed to detect preload dependence and predict fluid responsiveness. In this review, we take stock of the data published in the field over the past three years. Regarding the passive leg raising test, we detail the different stroke volume surrogates that have recently been described to measure its effects using minimally invasive and easily accessible methods. We review the limits of the test, especially in patients with intra-abdominal hypertension. Regarding the end-expiratory occlusion test, we also present recent investigations that have sought to measure its effects without an invasive measurement of cardiac output. Although the limits of interpretation of the respiratory variation of pulse pressure and of the diameter of the vena cava during mechanical ventilation are now well known, several recent studies have shown how changes in pulse pressure variation itself during other tests reflect simultaneous changes in cardiac output, allowing these tests to be carried out without its direct measurement. This is particularly the case during the tidal volume challenge, a relatively recent test whose reliability is increasingly well established. The mini-fluid challenge has the advantage of being easy to perform, but it requires direct measurement of cardiac output, like the classic fluid challenge. Initially described with echocardiography, recent studies have investigated other means of judging its effects. We highlight the problem of their precision, which is necessary to evidence small changes in cardiac output. Finally, we point out other tests that have appeared more recently, such as the Trendelenburg manoeuvre, a potentially interesting alternative for patients in the prone position.

Slope analysis for the prediction of fluid responsiveness by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients

Objective

Assessment of fluid responsiveness is problematic in intensive care unit patients. Lung recruitment maneuvers (LRM) can be used as a functional test to predict fluid responsiveness. We propose a new test to predict fluid responsiveness in mechanically ventilated patients by analyzing the variations in central venous pressure (CVP) and systemic arterial parameters during a prolonged sigh breath LRM without the use of a cardiac output measuring device.

Design

Prospective observational cohort study.

Setting

Intensive Care Unit, Saint-Etienne University Central Hospital.

Patients

Patients under mechanical ventilation, equipped with invasive arterial blood pressure, CVP, pulse contour analysis (PICCO™), requiring volume expansion, with no right ventricular dysfunction.

Interventions.

None.

Measurements and main results

CVP, systemic arterial parameters and stroke volume (SV) were recorded during prolonged LRM followed by a 500 mL fluid expansion to asses fluid responsiveness. 25 patients were screened and 18 patients analyzed. 9 patients were responders to volume expansion and 9 were not. Evaluation of hemodynamic parameters suggested the use of a linear regression model. Slopes for systolic arterial pressure, pulse pressure (PP), CVP and SV were all significantly different between responders and non-responders during the pressure increase phase of LRM (STEP-UP) (p = 0.022, p = 0.014, p = 0.006 and p = 0.038, respectively). PP and CVP slopes during STEP-UP were strongly predictive of fluid responsiveness with an AUC of 0.926 (95% CI, 0.78 to 1.00), sensitivity = 100%, specificity = 89% and an AUC = 0.901 (95% CI, 0.76 to 1.00), sensibility = 78%, specificity = 100%, respectively. Combining sensitivity of PP and specificity of CVP, prediction of fluid responsiveness can be achieved with 100% sensitivity and 100% specificity (AUC = 0.96; 95% CI, 0.90 to 1.00). One patient showed inconclusive values using the grey zone approach (5.5%).

Conclusions

In patients under mechanical ventilation with no right heart dysfunction, the association of PP and CVP slope analysis during a prolonged sigh breath LRM seems to offer a very promising method for prediction of fluid responsiveness without the use and associated cost of a cardiac output measurement device.

Trial registration

NCT04304521, IRBN902018/CHUSTE. Registered 11 March 2020, Fluid responsiveness predicted by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients (STEP-PEEP)

Changes in stroke volume induced by lung recruitment maneuver can predict fluid responsiveness during intraoperative lung-protective ventilation in prone position

Background

The present study aimed to evaluate the reliability of hemodynamic changes induced by lung recruitment maneuver (LRM) in predicting stroke volume (SV) increase after fluid loading (FL) in prone position.

Methods

Thirty patients undergoing spine surgery in prone position were enrolled. Lung-protective ventilation (tidal volume, 6–7 mL/kg; positive end-expiratory pressure, 5 cmH₂O) was provided to all patients. LRM (30 cmH₂O for 30 s) was performed. Hemodynamic variables including mean arterial pressure (MAP), heart rate, SV, SV variation (SVV), and pulse pressure variation (PPV) were simultaneously recorded before, during, and at 5 min after LRM and after FL (250 mL in 10 min). Receiver operating characteristic curves were generated to evaluate the predictability of SVV, PPV, and SV decrease by LRM (ΔSV_LRM) for SV responders (SV increase after FL > 10%). The gray zone approach was applied for ΔSV_LRM.

Results

Areas under the curve (AUCs) for ΔSV_LRM, SVV, and PPV to predict SV responders were 0.778 (95% confidence interval: 0.590–0.909), 0.563 (0.371–0.743), and 0.502 (0.315–0.689), respectively. The optimal threshold for ΔSV_LRM was 30% (sensitivity, 92.3%; specificity, 70.6%). With the gray zone approach, the inconclusive values ranged 25 to 75% for ΔSV_LRM (including 50% of enrolled patients).

Conclusion

In prone position, LRM-induced SV decrease predicted SV increase after FL with higher reliability than traditional dynamic indices. On the other hand, considering the relatively large gray zone in this study, future research is needed to further improve the clinical significance.

Trial registration

UMIN Clinical Trial Registry UMIN000027966. Registered 28th June 2017.

Pharmacodynamic analysis of a fluid challenge with 4 ml kg-1 over 10 or 20 min: a multicenter cross-over randomized clinical trial

Purpose

A number of studies performed in the operating room evaluated the hemodynamic effects of the fluid challenge (FC), solely considering the effect before and after the infusion. Few studies have investigated the pharmacodynamic effect of the FC on hemodynamic flow and pressure variables. We designed this trial aiming at describing the pharmacodynamic profile of two different FC infusion times, of a fixed dose of 4 ml kg⁻¹.

Methods

Forty-nine elective neurosurgical patients received two consecutive FCs of 4 ml kg⁻¹ of crystalloids in 10 (FC₁₀) or 20 (FC₂₀) minutes, in a random order. Fluid responsiveness was defined as stroke volume index increase ≥ 10%. We assessed the net area under the curve (AUC), the maximal percentage difference from baseline (d_max), time when the d_max was observed (t_max), change from baseline at 1-min (d₁) and 5-min (d₅) after FC end.

Results

After FC₁₀ and FC_20, 25 (51%) and 14 (29%) of 49 patients were classified as fluid responders (p = 0.001). With the exception of the AUCs of SAP and MAP, the AUCs of all the considered hemodynamic variables were comparable. The d_max and the t_max were overall comparable. In both groups, the hemodynamic effects on flow variables were dissipated within 5 min after FC end.

Conclusions

The infusion time of FC administration affects fluid responsiveness, being higher for FC₁₀ as compared to FC₂₀. The effect on flow variables of either FCs fades 5 min after the end of infusion.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10877-021-00756-3.

Changes in peripheral perfusion index during intraoperative end-expiratory occlusion tests do not predict the response to fluid administration in patients undergoing lung protective ventilation

INTRODUCTION

The end-expiratory occlusion test (EEOT) may predict the response to fluid administration in patients undergoing lung-protective ventilation, but arterial catheter insertion is necessary to evaluate changes in stroke volume (SV). The peripheral perfusion index is a potential noninvasive alternative to evaluate SV. The aim of this study is to investigate whether changes in perfusion index during an intraoperative EEOT can predict the response to fluid administration in patients undergoing lung-protective ventilation (tidal volume 7 ml/kg predicted body weight).

METHODS

Forty-one elective surgical patients were enrolled. The SV and perfusion index were recorded before (baseline), during a 40-s EEOT and after volume expansion (250 ml of lactated Ringer's solution over 10 min). Patients with an increase in SV greater than 10% after volume expansion were defined as responders. ΔPI (change in perfusion index between baseline and 20 (ΔPI₂₀) or 40 s (ΔPI₄₀) after the beginning of EEOT were calculated using: ΔPI₂₀ (%) = [(PI at 20 s after EEOT beginning - PI_baseline)/PI_baseline] × 100, ΔPI₄₀ (%) = [(PI at 40 s after EEO beginning - PI_baseline)/PI_baseline] × 100).

RESULTS

Sixteen patients were responders, and 25 were non-responders. The area under the receiver operating characteristics curves generated for ΔPI₂₀ and ΔPI₄₀ to predict response to a fluid challenge were 0.561 (95% CI 0.374-0.749) and 0.688 (95% CI 0.523-0.852), respectively.

CONCLUSION

Changes in perfusion index during intraoperative EEOT in patients undergoing lung-protective ventilation (7 ml/kg) were unable to predict the response to fluid administration.

Hemodynamic Changes via the Lung Recruitment Maneuver Can Predict Fluid Responsiveness in Stroke Volume and Arterial Pressure During One-Lung Ventilation

BACKGROUND

We aimed to evaluate the ability of lung recruitment maneuver-induced hemodynamic changes to predict fluid responsiveness in patients undergoing lung-protective ventilation during one-lung ventilation (OLV).

METHODS

Thirty patients undergoing thoracic surgery with OLV (tidal volume: 6 mL/kg of ideal body weight and positive end-expiratory pressure: 5 cm H2O) were enrolled. The study protocol began 30 minutes after starting OLV. Simultaneous recordings were performed for hemodynamic variables of heart rate, mean arterial pressure (MAP), stroke volume (SV), pulse pressure variation (PPV), and stroke volume variation (SVV) were recorded at 4 time points: before recruitment maneuver (continuous airway pressure: 30 cm H2O for 30 seconds), at the end of recruitment maneuver, and before and after volume loading (250 mL over 10 minutes). Patients were recognized as fluid responders if the increase in SV or MAP was >10%. Receiver operating characteristic curves for percent decrease in SV and MAP by recruitment maneuver (ΔSVRM and ΔMAPRM, respectively) were generated to evaluate the ability to discriminate fluid responders from nonresponders. The gray-zone approach was applied for ΔSVRM and ΔMAPRM.

RESULTS

Of 30 patients, there were 17 SV-responders (57%) and 12 blood pressure (BP)-responders (40%). Area under the curve (AUC) for ΔSVRM to discriminate SV-responders from nonresponders was 0.84 (95% confidence interval [CI], 0.67-0.95; P < .001). The best threshold for ΔSVRM to discriminate the SV-responders was -23.7% (95% CI, -41.2 to -17.8; sensitivity, 76.5% [95% CI, 50.1-93.2]; specificity, 84.6% [95% CI, 54.6-98.1]). For BP-responders, AUC for ΔMAPRM was 0.80 (95% CI, 0.61-0.92, P < .001). The best threshold for ΔMAPRM was -17.3% (95% CI, -23.9 to -5.1; sensitivity, 75.0% [95% CI, 42.8-94.5]; specificity, 77.8% [95% CI, 52.4-93.6]). With the gray-zone approach, the inconclusive range of ΔSVRM for SV-responders was -40.1% to -13.8% including 13 (43%) patients, and that of ΔMAPRM was -23.9% to -5.1%, which included 16 (53%) patients.

CONCLUSIONS

ΔSVRM and ΔMAPRM could predict hemodynamic responses after volume expansion during OLV.

Changes in corrected carotid flow time induced by recruitment maneuver predict fluid responsiveness in patients undergoing general anesthesia

Non-invasive methods to assess patients' fluid responsiveness during lung-protective ventilation are needed. We hypothesized changes in the corrected carotid flow time induced by the recruitment maneuver predict fluid responsiveness under general anesthesia. Thirty patients undergoing general anesthesia in the supine position were prospectively enrolled. The study protocol was conducted when the patient was hemodynamically stable during surgery. Flow time was measured on Doppler images of the common carotid artery. Carotid flow time, heart rate, stroke volume, stroke volume variation, and pulse pressure variation were recorded before and after a recruitment maneuver at a continuous airway pressure of 30 cmH₂O for 30 s, and before and after volume expansion with 250 mL for 10 min. Patients were defined as fluid responders if the increase in stroke volume was > 10% after volume expansion. Twenty patients (67%) were fluid responders. All Doppler images for carotid flow time were obtained within 30 s. Changes in the corrected flow time accurately predicted fluid responsiveness (area under the curve: 0.82, 95% confidence interval [CI] 0.64-0.94, p = 0.002). The optimal threshold for changes in the corrected flow time was - 11.7% with a sensitivity of 95.0% (95% CI 75.1-99.9%) and a specificity of 80.0% (95% CI 44.4-97.5%). The gray-zone of changes in the corrected flow time was from - 25.1 to - 12.2% and included 12 patients (40%). Changes in the corrected carotid flow time were a useful, technically easy-to-perform, and non-invasive method to predict fluid responsiveness without a need for hemodynamic monitoring or arterial cannulation.

The use of pulse pressure variation for predicting impairment of microcirculatory blood flow

Dynamic parameters of preload have been widely recommended to guide fluid therapy based on the principle of fluid responsiveness and with regard to cardiac output. An equally important aspect is however to also avoid volume-overload. This accounts particularly when capillary leakage is present and volume-overload will promote impairment of microcirculatory blood flow. The aim of this study was to evaluate, whether an impairment of intestinal microcirculation caused by volume-load potentially can be predicted using pulse pressure variation in an experimental model of ischemia/reperfusion injury. The study was designed as a prospective explorative large animal pilot study. The study was performed in 8 anesthetized domestic pigs (German landrace). Ischemia/reperfusion was induced during aortic surgery. 6 h after ischemia/reperfusion-injury measurements were performed during 4 consecutive volume-loading-steps, each consisting of 6 ml kg⁻¹ bodyweight⁻¹. Mean microcirculatory blood flow (mean Flux) of the ileum was measured using direct laser-speckle-contrast-imaging. Receiver operating characteristic analysis was performed to determine the ability of pulse pressure variation to predict a decrease in microcirculation. A reduction of ≥ 10% mean Flux was considered a relevant decrease. After ischemia–reperfusion, volume-loading-steps led to a significant increase of cardiac output as well as mean arterial pressure, while pulse pressure variation and mean Flux were significantly reduced (Pairwise comparison ischemia/reperfusion-injury vs. volume loading step no. 4): cardiac output (l min⁻¹) 1.68 (1.02–2.35) versus 2.84 (2.15–3.53), p = 0.002, mean arterial pressure (mmHg) 29.89 (21.65–38.12) versus 52.34 (43.55–61.14), p < 0.001, pulse pressure variation (%) 24.84 (17.45–32.22) versus 9.59 (1.68–17.49), p = 0.004, mean Flux (p.u.) 414.95 (295.18–534.72) versus 327.21 (206.95–447.48), p = 0.006. Receiver operating characteristic analysis revealed an area under the curve of 0.88 (CI 95% 0.73–1.00; p value < 0.001) for pulse pressure variation for predicting a decrease of microcirculatory blood flow. The results of our study show that pulse pressure variation does have the potential to predict decreases of intestinal microcirculatory blood flow due to volume-load after ischemia/reperfusion-injury. This should encourage further translational research and might help to prevent microcirculatory impairment due to excessive fluid resuscitation and to guide fluid therapy in the future.

Prediction of fluid responsiveness using lung recruitment manoeuvre in paediatric patients receiving lung-protective ventilation: A prospective observational study

BACKGROUND

Pressure-based dynamic variables are poor predictors of fluid responsiveness in children, and their predictability is expected to reduce further during lung-protective ventilation with a low tidal volume.

OBJECTIVE

We hypothesised that lung recruitment manoeuvre (LRM)-induced changes in dynamic variables improve their ability to predict fluid responsiveness in children.

DESIGN

Prospective observational study.

SETTING

Tertiary care children's hospital, single-centre study performed from June 2017 to May 2019.

PATIENTS

We included patients less than 7 years of age undergoing cardiac surgery. Neonates and patients with pulmonary hypertension, significant dysrhythmia, ventricular ejection fraction of less than 30% or pulmonary disease were excluded.

INTERVENTION

All patients were provided with lung-protective volume-controlled ventilation (tidal volume 6 ml kg-1, positive end-expiratory pressure 6 cmH2O). A LRM was applied with a continuous inspiratory pressure of 25 cmH2O for 20 s.

MAIN OUTCOME MEASURE

The ability of dynamic variables to predict fluid responsiveness was evaluated by the area under the receiver operating characteristic curve [area under the curve (AUC)]. Fluid responsiveness was defined as an increase in the cardiac index by more than 15% with crystalloid administration (10 ml kg-1).

RESULTS

Thirty patients were included in the final analysis, of whom 19 were responders. The baseline pleth variability index (PVI) (AUC 0.794, 95% confidence interval 0.608 to 0.919, P < 0.001) and LRM-induced PVI (AUC 0.711, 95% confidence interval 0.517 to 0.861, P = 0.026) could predict fluid responsiveness. The respiratory variation of pulse oximetry photoplethysmographic waveform and pulse pressure variation did not predict fluid responsiveness regardless of the LRM.

CONCLUSION

The PVI is effective in predicting fluid responsiveness in paediatric patients with lung-protective ventilation regardless of a LRM. However, the LRM did not improve the ability of the other dynamic variables to predict fluid responsiveness in these patients.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier: NCT03184961.

Functional Hemodynamic Monitoring With a Wireless Ultrasound Patch

In this Emerging Technology Review, a novel, wireless, wearable Doppler ultrasound patch is described as a tool for resuscitation. The device is designed, foremost, as a functional hemodynamic monitor-a simple, fast, and consistent method for measuring hemodynamic change with preload variation. More generally, functional hemodynamic monitoring is a paradigm that helps predict stroke volume response to additional intravenous volume. Because Doppler ultrasound of the left ventricular outflow tract noninvasively measures stroke volume in realtime, it increasingly is deployed for this purpose. Nevertheless, Doppler ultrasound in this manner is cumbersome, especially when repeat assessments are needed. Accordingly, peripheral arteries have been studied and various measures from the common carotid artery Doppler signal act as windows to the left ventricle. Yet, handheld Doppler ultrasound of a peripheral artery is susceptible to human measurement error and statistical limitations from inadequate beat sample size. Therefore, a wearable Doppler ultrasound capable of continuous assessment minimizes measurement inconsistencies and smooths inherent physiologic variation by sampling many more cardiac cycles. Reaffirming clinical studies, the ultrasound patch tracks immediate SV change with excellent accuracy in healthy volunteers when cardiac preload is altered by various maneuvers. The wearable ultrasound also follows jugular venous Doppler, which qualitatively trends right atrial pressure. With further clinical research and the application of artificial intelligence, the monitoring modalities with this new technology are manifold.

Focused ultrasonography for septic shock resuscitation

PURPOSE OF REVIEW

Severe sepsis with septic shock is the most common cause of death among critically ill patients. Mortality has decreased substantially over the last decade but recent data has shown that opportunities remain for the improvement of early and targeted therapy. This review discusses published data regarding the role of focused ultrasonography in septic shock resuscitation.

RECENT FINDINGS

Early categorization of the cardiovascular phenotypes with echocardiography can be crucial for timely diagnosis and targeted therapy of patients with septic shock. In the last few years, markers of volume status and volume responsiveness have been investigated, serving as valuable tools for targeting volume therapy in the care of both spontaneously breathing and mechanically ventilated patients. In tandem, investigators have highlighted findings of extravascular volume with ultrasonographic evaluation to compliment de-escalation of resuscitation efforts when appropriate. Furthermore, special attention has been given to resuscitation efforts of patients in septic shock with right ventricular failure.

SUMMARY

Severe sepsis with septic shock is an insidious disease process that continues to take lives. In more recent years, data have emerged suggesting the utility of bedside ultrasonography for early cardiovascular categorization, goal directed resuscitation, and appropriate cardiovascular support based on its changing phenotypes.

Evaluation of alveolar recruitment maneuver on respiratory resistance during general anesthesia: a prospective observational study

Background

Alveolar recruitment maneuvers enable easily reopening nonaerated lung regions via a transient elevation in transpulmonary pressure. To evaluate the effect of these maneuvers on respiratory resistance, we used an oscillatory technique during mechanical ventilation. This study was conducted to assess the effect of the alveolar recruitment maneuvers on respiratory resistance under routine anesthesia. We hypothesized that respiratory resistance at 5 Hz (R5) after the maneuver would be decreased after the lung aeration.

Methods

After receiving the ethics committee’s approval, we enrolled 33 patients who were classified with an American Society of Anesthesiologists physical status of 1, 2 or 3 and were undergoing general anesthesia for transurethral resection of a bladder tumor within a 12-month period from 2017 to 2018. The recruitment maneuver was performed 30 min after endotracheal intubation. The maneuver consisted of sustained manual inflation of the anesthesia reservoir bag to a peak inspiratory pressure of 40 cmH₂O for 15 s, including 5 s of gradually increasing the peak inspiratory pressure. Respiratory resistance was measured using the forced oscillation technique before and after the maneuver, and the mean R5 was calculated during the expiratory phase. The respiratory resistance and ventilator parameter results were analyzed using paired Student’s t-tests, and p < 0.05 was considered statistically significant.

Results

We analyzed 31 patients (25 men and 6 women). R5 was 7.3 ± 1.6 cmH₂O/L/sec before the recruitment maneuver during mechanical ventilation and was significantly decreased to 6.4 ± 1.7 cmH₂O/L/sec after the maneuver. Peak inspiratory pressure and plateau pressure were significantly decreased, and pulmonary compliance was increased, although the values were not clinically relevant.

Conclusion

The recruitment maneuver decreased respiratory resistance and increased lung compliance during mechanical ventilation.

Trial registration

Name of registry: Japan Medical Association Center for Clinical Trials.

Trial registration number: reference JMA-IIA00136.

Date of registration: 2 September 2013.

URL of trial registry record: https://dbcentre3.jmacct.med.or.jp/JMACTR/App/JMACTRE02_04/JMACTRE02_04.aspx?kbn=3&seqno=3582

Can the behavior of blood pressure after elevation of the positive end-expiratory pressure help to determine the fluid responsiveness status in patients with septic shock?

OBJECTIVE

To evaluate whether the decrease in blood pressure caused by the increase in the positive end-expiratory pressure corresponds to the pulse pressure variation as an indicator of fluid responsiveness.

METHODS

This exploratory study prospectively included 24 patients with septic shock who were mechanically ventilated and subjected to three stages of elevation of the positive end-expiratory pressure: from 5 to 10cmH2O (positive end-expiratory pressure level 1), from 10 to 15cmH2O (positive end-expiratory pressure level 2), and from 15 to 20cmH2O (positive end-expiratory pressure level 3). Changes in systolic blood pressure, mean arterial pressure, and pulse pressure variation were evaluated during the three maneuvers. The patients were classified as responsive (pulse pressure variation ≥ 12%) or unresponsive to volume replacement (pulse pressure variation < 12%).

RESULTS

The best performance at identifying patients with pulse pressure variation ≥ 12% was observed at the positive end-expiratory pressure level 2: -9% systolic blood pressure variation (area under the curve 0.73; 95%CI: 0.49 - 0.79; p = 0.04), with a sensitivity of 63% and specificity of 80%. Concordance was low between the variable with the best performance (variation in systolic blood pressure) and pulse pressure variation ≥ 12% (kappa = 0.42; 95%CI: 0.19 - 0.56). The systolic blood pressure was < 90mmHg at positive end-expiratory pressure level 2 in 29.2% of cases and at positive end-expiratory pressure level 3 in 41.63% of cases.

CONCLUSION

Variations in blood pressure in response to the increase in positive end-expiratory pressure do not reliably reflect the behavior of the pulse pressure as a measure to identify the fluid responsiveness status.

Evaluation of fluid responsiveness during COVID-19 pandemic: what are the remaining choices?

Non-protocolized fluid administration in critically ill patients, especially those with acute respiratory distress syndrome (ARDS), is associated with poor outcomes. Therefore, fluid administration in patients with Coronavirus disease (COVID-19) should be properly guided. Choice of an index to guide fluid management during a pandemic with mass patient admissions carries an additional challenge due to the relatively limited resources. An ideal test for assessment of fluid responsiveness during this pandemic should be accurate in ARDS patients, economic, easy to interpret by junior staff, valid in patients in the prone position and performed with minimal contact with the patient to avoid spread of infection. Patients with COVID-19 ARDS are divided into two phenotypes (L phenotype and H phenotype) according to their lung compliance. Selection of the proper index for fluid responsiveness varies according to the patient phenotype. Heart–lung interaction methods can be used only in patients with L phenotype ARDS. Real-time measures, such a pulse pressure variation, are more appropriate for use during this pandemic compared to ultrasound-derived measures, because contamination of the ultrasound machine can spread infection. Preload challenge tests are suitable for use in all COVID-19 patients. Passive leg raising test is relatively better than mini-fluid challenge test, because it can be repeated without overloading the patient with fluids. Trendelenburg maneuver is a suitable alternative to the passive leg raising test in patients with prone position. If a cardiac output monitor was not available, the response to the passive leg raising test could be traced by measurement of the pulse pressure or the perfusion index. Preload modifying maneuvers, such as tidal volume challenge, can also be used in COVID-19 patients, especially if the patient was in the gray zone of other dynamic tests. However, the preload modifying maneuvers were not extensively evaluated outside the operating room. Selection of the proper test would vary according to the level of healthcare in the country and the load of admissions which might be overwhelming. Evaluation of the volume status should be comprehensive; therefore, the presence of signs of volume overload such as lower limb edema, lung edema, and severe hypoxemia should be considered beside the usual indices for fluid responsiveness.

Intra-Abdominal Hypertension Is Responsible for False Negatives to the Passive Leg Raising Test

OBJECTIVES

To compare the passive leg raising test ability to predict fluid responsiveness in patients with and without intra-abdominal hypertension.

DESIGN

Observational study.

SETTING

Medical ICU.

PATIENTS

Mechanically ventilated patients monitored with a PiCCO2 device (Pulsion Medical Systems, Feldkirchen, Germany) in whom fluid expansion was planned, with (intra-abdominal hypertension+) and without (intra-abdominal hypertension-) intra-abdominal hypertension, defined by an intra-abdominal pressure greater than or equal to 12 mm Hg (bladder pressure).

INTERVENTIONS

We measured the changes in cardiac index during passive leg raising and after volume expansion. The passive leg raising test was defined as positive if it increased cardiac index greater than or equal to 10%. Fluid responsiveness was defined by a fluid-induced increase in cardiac index greater than or equal to 15%.

MEASUREMENTS AND MAIN RESULTS

We included 60 patients, 30 without intra-abdominal hypertension (15 fluid responders and 15 fluid nonresponders) and 30 with intra-abdominal hypertension (21 fluid responders and nine fluid nonresponders). The intra-abdominal pressure at baseline was 4 ± 3 mm Hg in intra-abdominal hypertension- and 20 ± 6 mm Hg in intra-abdominal hypertension+ patients (p < 0.01). In intra-abdominal hypertension- patients with fluid responsiveness, cardiac index increased by 25% ± 19% during passive leg raising and by 35% ± 14% after volume expansion. The passive leg raising test was positive in 14 patients. The passive leg raising test was negative in all intra-abdominal hypertension- patients without fluid responsiveness. In intra-abdominal hypertension+ patients with fluid responsiveness, cardiac index increased by 10% ± 14% during passive leg raising (p = 0.01 vs intra-abdominal hypertension- patients) and by 32% ± 18% during volume expansion (p = 0.72 vs intra-abdominal hypertension- patients). Among these patients, the passive leg raising test was negative in 15 patients (false negatives) and positive in six patients (true positives). Among the nine intra-abdominal hypertension+ patients without fluid responsiveness, the passive leg raising test was negative in all but one patient. The area under the receiver operating characteristic curve of the passive leg raising test for detecting fluid responsiveness was 0.98 ± 0.02 (p < 0.001 vs 0.5) in intra-abdominal hypertension- patients and 0.60 ± 0.11 in intra-abdominal hypertension+ patients (p = 0.37 vs 0.5).

CONCLUSIONS

Intra-abdominal hypertension is responsible for some false negatives to the passive leg raising test.

Perioperative Fluid Therapy for Major Surgery

A moderately liberal IV fluid regimen, using a balanced crystalloid, and consideration of the use of an advanced hemodynamic monitor in a setting of an enhanced recovery pathway are recommended for major surgery.

Supplemental Digital Content is available in the text.

A Carotid Doppler Patch Accurately Tracks Stroke Volume Changes During a Preload-Modifying Maneuver in Healthy Volunteers

Objectives:

Detecting instantaneous stroke volume change in response to altered cardiac preload is the physiologic foundation for determining preload responsiveness.

Design:

Proof-of-concept physiology study.

Setting:

Research simulation laboratory.

Subjects:

Twelve healthy volunteers.

Interventions:

A wireless continuous wave Doppler ultrasound patch was used to measure carotid velocity time integral and carotid corrected flow time during a squat maneuver. The Doppler patch measurements were compared with simultaneous stroke volume measurements obtained from a noninvasive cardiac output monitor.

Measurements and Main Results:

From stand to squat, stroke volume increased by 24% while carotid velocity time integral and carotid corrected flow time increased by 32% and 9%, respectively. From squat to stand, stroke volume decreased by 13%, while carotid velocity time integral and carotid corrected flow time decreased by 24% and 10%, respectively. Both changes in carotid velocity time integral and corrected flow time were closely correlated with changes in stroke volume (r² = 0.81 and 0.62, respectively). The four-quadrant plot found a 100% concordance rate between changes in stroke volume and both changes in carotid velocity time integral and changes in corrected flow time. A change in carotid velocity time integral greater than 15% predicted a change in stroke volume greater than 10% with a sensitivity of 95% and a specificity of 92%. A change in carotid corrected flow time greater than 4% predicted a change in stroke volume greater than 10% with a sensitivity of 90% and a specificity of 92%.

Conclusions:

In healthy volunteers, both carotid velocity time integral and carotid corrected flow time measured by a wireless Doppler patch were useful to track changes in stroke volume induced by a preload-modifying maneuver with high sensitivity and specificity.

Effect of shortening preoperative time of fasting and forbidding water on clinical outcome of elderly patients with gastrointestinal cancer

BACKGROUND

Prolonged fasting and water deprivation before surgery can easily lead to adverse reactions such as hunger, thirst, hypoglycemia, etc., especially in elderly patients. At present, most studies support shortening the duration of preoperative fasting and water, while domestic guidelines for preoperative fasting and water deprivation are for children, and there is no authoritative guide for adults.

AIM

To observe the effect of shortening preoperative time of fasting and forbidding water on the clinical outcome of elderly patients with gastrointestinal cancer.

METHODS

One hundred elderly patients with gastrointestinal cancer were divided into two groups (n = 50 each): experimental group and control group. The experimental group was fasted for 12 h and forbidden to drink water for 6 h before operation, and the control group was fasted for 6 h and forbidden to drink water for 2 h before operation. The changes of preoperative response, anesthesia effect, recovery time, hemodynamic index [mean arterial pressure (MAP), heart rate (HR)], and pulse oxygen saturation (SPO₂) before and 5 min after surgery were recorded. Postoperative rehabilitation effect was also recorded.

RESULTS

There were 6 (12%) cases in the experimental group and 29 (58%) in the control group. Preoperative reactions such as thirst, starvation, fatigue, and hope for eating occurred; the incidence between the two groups was statistically significant (χ² = 23.253, P < 0.001). The MAP, HR, and SPO₂ were significantly decreased in the experimental group and the control group at 5 min after operation (P < 0.05). The HR and SPO₂ at 5 min after operation in the experimental group were significantly higher than those in the control group (P > 0.05), although there was no significant difference in the MAP between the two groups (P < 0.05). There was no significant difference in the anesthesia effect between the two groups (P > 0.05), but there was a significant difference in the recovery time between them (t = -3.121, P = 0.002). There were significant differences in time to postoperative gastric tube removal, time to anal exhaust, time to body temperature recovery, and hospitalization days between the two groups (P < 0.05). There were no significant differences in postoperative nausea, postoperative vomiting, postoperative thirst, hunger, or postoperative pneumonia between the two groups (P > 0.05).

CONCLUSION

Reasonable arrangement of preoperative fasting time in elderly patients with gastrointestinal cancer may reduce the preoperative discomfort of patients and effectively improve the therapeutic effects, which is of great significance for the smooth performance of surgery and the promotion of postoperative rehabilitation.

Do changes in perfusion index reflect changes in stroke volume during preload-modifying manoeuvres?

Changes in stroke volume (deltaSV) induced by a lung recruitment manoeuvre (LRM) have been shown to accurately predict fluid responsiveness during protective mechanical ventilation. Cardiac output monitors are used in a limited number of surgical patients. In contrast, all patients are monitored with a pulse oximeter, that may enable the continuous monitoring of a peripheral perfusion index (PI). We postulated that changes in PI (deltaPI) may reflect deltaSV during brief modifications of cardiac preload. We studied 47 patients undergoing neurosurgery and ventilated with a tidal volume of 6-8 ml/kg. All patients were monitored with a pulse contour system enabling the continuous monitoring of SV and with a pulse oximeter enabling the continuous monitoring of PI. LRMs were performed by increasing airway pressure up to 30 cmH₂0 for 30 s. Fluid loads (250 ml of saline 0.9% in 10 min) were performed only in patients who experienced a deltaSV > 30% during LRMs (potential fluid responders). LRMs induced a 26% decrease in SV (p < 0.05) and a 27% decrease in PI (p < 0.05). We observed a fair relationship between deltaPI and deltaSV (r² = 0.34). A deltaPI ≥ 26% predicted a deltaSV > 30% with a sensitivity of 83% and a specificity of 78%  (AUC  =  0.84, 95%CI 0.71-0.93). 24 patients experienced a deltaSV > 30% and subsequently received fluid. Fluid loads induced a 16% increase in SV and a 17% increase in PI, but fluid-induced deltaPI and deltaSV were weakly correlated (r² = 0.19). In neurosurgical patients, we conclude that deltaPI may be used as a surrogate for deltaSV during LRMs but not during fluid loading.

Evaluation of least significant changes of pulse contour analysis-derived parameters

Background

Many maneuvers assessing fluid responsiveness (minifluid challenge, lung recruitment maneuver, end-expiratory occlusion test, passive leg raising) are considered as positive when small variations in cardiac index, stroke volume index, stroke volume variation or pulse pressure variation occur. Pulse contour analysis allows continuous and real-time cardiac index, stroke volume, stroke volume variation and pulse pressure variation estimations. To use these maneuvers with pulse contour analysis, the knowledge of the minimal change that needs to be measured by a device to recognize a real change (least significant change) has to be studied. The aim of this study was to evaluate the least significant change of cardiac index, stroke volume index, stroke volume variation and pulse pressure variation obtained using pulse contour analysis (ProAQT^®, Pulsion Medical System, Germany).

Methods

In this observational study, we included 50 mechanically ventilated patients undergoing neurosurgery in the operating room. Cardiac index, stroke volume index, pulse pressure variation and stroke volume variation obtained using ProAQT^® (Pulsion Medical System, Germany) were recorded every 12 s during 15-min steady-state periods. Least significant changes were calculated every minute.

Results

Least significant changes statistically differed over time for cardiac index, stroke volume index, pulse pressure variation and stroke volume variation (p < 0.001). Least significant changes ranged from 1.3 to 0.7% for cardiac index, from 1.3 to 0.8% for stroke volume index, from 10 to 4.9% for pulse pressure variation and from 10.8 to 4.3% for stroke volume variation.

Conclusion

To conclude, the present study suggests that pulse contour analysis is able to detect rapid and small changes in cardiac index and stroke volume index, but the interpretation of rapid and small changes of pulse pressure variation and stroke volume variation must be done with caution.

What the anaesthesiologist needs to know about heart-lung interactions

The impact of positive pressure ventilation extends the effect on lungs and gas exchange because the altered intra-thoracic pressure conditions influence determinants of cardiovascular function. These mechanisms are called heart-lung interactions, which conceptually can be divided into two components (1) The effect of positive airway pressure on the cardiovascular system, which may be more or less pronounced under various pathologic cardiac conditions, and (2) The effect of cyclic airway pressure swing on the cardiovascular system, which can be useful in the interpretation of the individual patient's current haemodynamic state. It is imperative for the anaesthesiologist to understand the fundamental mechanisms of heart-lung interactions, as they are a foundation for the understanding of optimal, personalised cardiovascular treatment of patients undergoing surgery in general anaesthesia. The aim of this review is thus to describe what the anaesthesiologist needs to know about heart-lung interactions.

Functional hemodynamic tests: a systematic review and a metanalysis on the reliability of the end-expiratory occlusion test and of the mini-fluid challenge in predicting fluid responsiveness

Background

Bedside functional hemodynamic assessment has gained in popularity in the last years to overcome the limitations of static or dynamic indexes in predicting fluid responsiveness. The aim of this systematic review and metanalysis of studies is to investigate the reliability of the functional hemodynamic tests (FHTs) used to assess fluid responsiveness in adult patients in the intensive care unit (ICU) and operating room (OR).

Methods

MEDLINE, EMBASE, and Cochrane databases were screened for relevant articles using a FHT, with the exception of the passive leg raising. The QUADAS-2 scale was used to assess the risk of bias of the included studies. In-between study heterogeneity was assessed through the I² indicator. Bias assessment graphs were plotted, and Egger’s regression analysis was used to evaluate the publication bias. The metanalysis determined the pooled area under the receiving operating characteristic (ROC) curve, sensitivity, specificity, and threshold for two FHTs: the end-expiratory occlusion test (EEOT) and the mini-fluid challenge (FC).

Results

After text selection, 21 studies met the inclusion criteria, 7 performed in the OR, and 14 in the ICU between 2005 and 2018. The search included 805 patients and 870 FCs with a median (IQR) of 39 (25–50) patients and 41 (30–52) FCs per study. The median fluid responsiveness was 54% (45–59). Ten studies (47.6%) adopted a gray zone analysis of the ROC curve, and a median (IQR) of 20% (15–51) of the enrolled patients was included in the gray zone. The pooled area under the ROC curve for the end-expiratory occlusion test (EEOT) was 0.96 (95%CI 0.92–1.00). The pooled sensitivity and specificity were 0.86 (95%CI 0.74–0.94) and 0.91 (95%CI 0.85–0.95), respectively, with a best threshold of 5% (4.0–8.0%). The pooled area under the ROC curve for the mini-FC was 0.91 (95%CI 0.85–0.97). The pooled sensitivity and specificity were 0.82 (95%CI 0.76–0.88) and 0.83 (95%CI 0.77–0.89), respectively, with a best threshold of 5% (3.0–7.0%).

Conclusions

The EEOT and the mini-FC reliably predict fluid responsiveness in the ICU and OR. Other FHTs have been tested insofar in heterogeneous clinical settings and, despite promising results, warrant further investigations.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2545-z) contains supplementary material, which is available to authorized users.

Sigh maneuver to enhance assessment of fluid responsiveness during pressure support ventilation

Background

Assessment of fluid responsiveness is problematic in intensive care unit (ICU) patients, in particular for those undergoing modes of partial support, such as pressure support ventilation (PSV). We propose a new test, based on application of a ventilator-generated sigh, to predict fluid responsiveness in ICU patients undergoing PSV.

Methods

This was a prospective bi-centric interventional study conducted in two general ICUs. In 40 critically ill patients with a stable ventilatory PSV pattern and requiring volume expansion (VE), we assessed the variations in arterial systolic pressure (SAP), pulse pressure (PP) and stroke volume index (SVI) consequent to random application of 4-s sighs at three different inspiratory pressures. A radial arterial signal was directed to the MOSTCARE™ pulse contour hemodynamic monitoring system for hemodynamic measurements. Data obtained during sigh tests were recorded beat by beat, while all the hemodynamic parameters were averaged over 30 s for the remaining period of the study protocol. VE consisted of 500 mL of crystalloids over 10 min. A patient was considered a responder if a VE-induced increase in cardiac index (CI) ≥ 15% was observed.

Results

The slopes for SAP, SVI and PP of were all significantly different between responders and non-responders (p < 0.0001, p = 0.0004 and p < 0.0001, respectively). The AUC of the slope of SAP (0.99; sensitivity 100.0% (79.4–100.0%) and specificity 95.8% (78.8–99.9%) was significantly greater than the AUC for PP (0.91) and SVI (0.83) (p = 0.04 and 0.009, respectively). The SAP slope best threshold value of the ROC curve was − 4.4° from baseline. The only parameter found to be independently associated with fluid responsiveness among those included in the logistic regression was the slope for SAP (p = 0.009; odds ratio 0.27 (95% confidence interval (CI₉₅) 0.10–0.70)). The effects produced by the sigh at 35 cmH₂0 (Sigh₃₅) are significantly different between responders and non-responders. For a 35% reduction in PP from baseline, the AUC was 0.91 (CI₉₅ 0.82–0.99), with sensitivity 75.0% and specificity 91.6%.

Conclusions

In a selected ICU population undergoing PSV, analysis of the slope for SAP after the application of three successive sighs and the nadir of PP after Sigh₃₅ reliably predict fluid responsiveness.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12615001232527. Registered on 10 November 2015.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2294-4) contains supplementary material, which is available to authorized users.

Changes in stroke volume during an alveolar recruitment maneuvers through a stepwise increase in positive end expiratory pressure and transient continuous positive airway pressure in anesthetized patients. A prospective observational pilot study

Background and Aims:

Recruitment maneuvers may be used during anesthesia as part of perioperative protective ventilation strategy. However, the hemodynamic effect of recruitment maneuvers remain poorly documented in this setting.

Material and Methods:

This was a prospective observational study performed in operating theatre including patients scheduled for major vascular surgery. Patients were monitored with invasive arterial pressure and esophageal doppler. After induction of general anesthesia, before surgery began, preload optimization based on stroke volume (SV) variation following fluid challenge was performed. Then, an alveolar recruitment maneuver (ARM) through stepwise increase in positive end expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) was performed. Hemodynamic data were noted before, during, and after the alveolar recruitment maneuver.

Results:

ARM through stepwise increase in PEEP and CPAP were applied in 22 and 14 preload independent patients, respectively. Relative changes in SV during ARMs were significantly greater in the ARM_CPAP group (-39 ± 20%) as compared to the ARM_PEEP group (-15 ± 22%; P = 0.002). The difference (95% CI) in relative decrease in SV between ARM_CPAP and ARM_PEEP groups was -24% (-38 to -9; P = 0.001). Changes in arterial pressure, cardiac index, pulse pressure variation, peak velocity, and corrected flow time measures were not different between groups.

Conclusion:

During anesthesia, in preload independent patients, ARMs through CPAP resulted in a significantly greater decrease in SV than stepwise increase in PEEP. During anesthesia, ARM should be used cautiously.