Plethysmographic variation index predicts fluid responsiveness in ventilated patients in the early phase of septic shock in the emergency department: a pilot study

Assessment of fluid responsiveness using pulse pressure variation, stroke volume variation, plethysmographic variability index, central venous pressure, and inferior vena cava variation in patients undergoing mechanical ventilation: a systematic review and meta-analysis

IMPORTANCE

Maneuvers assessing fluid responsiveness before an intravascular volume expansion may limit useless fluid administration, which in turn may improve outcomes.

OBJECTIVE

To describe maneuvers for assessing fluid responsiveness in mechanically ventilated patients.

REGISTRATION

The protocol was registered at PROSPERO: CRD42019146781.

INFORMATION SOURCES AND SEARCH

PubMed, EMBASE, CINAHL, SCOPUS, and Web of Science were search from inception to 08/08/2023.

STUDY SELECTION AND DATA COLLECTION

Prospective and intervention studies were selected.

STATISTICAL ANALYSIS

Data for each maneuver were reported individually and data from the five most employed maneuvers were aggregated. A traditional and a Bayesian meta-analysis approach were performed.

RESULTS

A total of 69 studies, encompassing 3185 fluid challenges and 2711 patients were analyzed. The prevalence of fluid responsiveness was 49.9%. Pulse pressure variation (PPV) was studied in 40 studies, mean threshold with 95% confidence intervals (95% CI) = 11.5 (10.5-12.4)%, and area under the receiver operating characteristics curve (AUC) with 95% CI was 0.87 (0.84-0.90). Stroke volume variation (SVV) was studied in 24 studies, mean threshold with 95% CI = 12.1 (10.9-13.3)%, and AUC with 95% CI was 0.87 (0.84-0.91). The plethysmographic variability index (PVI) was studied in 17 studies, mean threshold = 13.8 (12.3-15.3)%, and AUC was 0.88 (0.82-0.94). Central venous pressure (CVP) was studied in 12 studies, mean threshold with 95% CI = 9.0 (7.7-10.1) mmHg, and AUC with 95% CI was 0.77 (0.69-0.87). Inferior vena cava variation (∆IVC) was studied in 8 studies, mean threshold = 15.4 (13.3-17.6)%, and AUC with 95% CI was 0.83 (0.78-0.89).

CONCLUSIONS

Fluid responsiveness can be reliably assessed in adult patients under mechanical ventilation. Among the five maneuvers compared in predicting fluid responsiveness, PPV, SVV, and PVI were superior to CVP and ∆IVC. However, there is no data supporting any of the above mentioned as being the best maneuver. Additionally, other well-established tests, such as the passive leg raising test, end-expiratory occlusion test, and tidal volume challenge, are also reliable.

Passive leg raising test induced changes in plethysmographic variability index to assess fluid responsiveness in critically ill mechanically ventilated patients with acute circulatory failure

BACKGROUND

Passive leg raising (PLR) reliably predicts fluid responsiveness but requires a real-time cardiac index (CI) measurement or the presence of an invasive arterial line to achieve this effect. The plethysmographic variability index (PVI), an automatic measurement of the respiratory variation of the perfusion index, is non-invasive and continuously displayed on the pulse oximeter device. We tested whether PLR-induced changes in PVI (ΔPVIPLR) could accurately predict fluid responsiveness in mechanically ventilated patients with acute circulatory failure.

METHODS

This was a secondary analysis of an observational prospective study. We included 29 mechanically ventilated patients with acute circulatory failure in this study. We measured PVI (Radical-7 device; Masimo Corp., Irvine, CA) and CI (Echocardiography) before and during a PLR test and before and after volume expansion of 500 mL of crystalloid solution. A volume expansion-induced increase in CI of >15% defined fluid responsiveness. To investigate whether ΔPVIPLR can predict fluid responsiveness, we determined areas under the receiver operating characteristic curves (AUROCs) and gray zones for ΔPVIPLR.

RESULTS

Of the 29 patients, 27 (93.1%) received norepinephrine. The median tidal volume was 7.0 [IQR: 6.6-7.6] mL/kg ideal body weight. Nineteen patients (65.5%) were classified as fluid responders (increase in CI > 15% after volume expansion). Relative ΔPVIPLR accurately predicted fluid responsiveness with an AUROC of 0.89 (95%CI: 0.72-0.98, p < 0.001). A decrease in PVI ≤ -24.1% induced by PLR detected fluid responsiveness with a sensitivity of 95% (95%CI: 74-100%) and a specificity of 80% (95%CI: 44-97%). Gray zone was acceptable, including 13.8% of patients. The correlations between the relative ΔPVIPLR and changes in CI induced by PLR and by volume expansion were significant (r = -0.58, p < 0.001, and r = -0.65, p < 0.001; respectively).

CONCLUSIONS

In sedated and mechanically ventilated ICU patients with acute circulatory failure, PLR-induced changes in PVI accurately predict fluid responsiveness with an acceptable gray zone.

TRIAL REGISTRATION

ClinicalTrials.govNCT03225378.

Assessment of pleth variability index in volume changes during ultrafiltration process

OBJECTIVES:

Pleth variability index (PVI) has been studied mostly in mechanically ventilated patients, and the role of PVI in predicting volume status and volume changes among spontaneously breathing patients is not clear in the literature. We hypothesized that hemodialysis (HD) can be a valid model for a simulation that can be evaluated the correlation of PVI with fluid changes in various volume states. The aim of this study was to investigate the utility of PVI for assessing volume changes in HD patients who are breathing spontaneously.

METHODS:

This prospective, observational study included patients aged 18 years or older who had end-stage renal failure and presented for routine HD between December 2019 and January 2020. PVI values were measured before and after HD session. Changes in PVI levels were compared according to the amount of ultrafiltration.

RESULTS:

A total of sixty patients were included. Mean PVI level before HD (20.7% ± 5%) showed a statistically significant increase to 27.7% ± 6% after HD session (P < 0.001). According to the amount of fluid removed during HD, the changes in PVI were statistically significant (P = 0.015). There was a strong correlation between ΔPVI and ultrafiltrated volume (r = 0.744, P < 0.001).

CONCLUSION:

The fluid removed by HD caused increase in PVI, and the increase was strongly correlated with the amount of volume change. Bedside monitoring of PVI may provide the clinicians with useful information for monitoring the volume status in critically ill patients with spontaneous breathing.

Point-of-care ultrasound assessment of the inferior vena cava distensibility index in mechanically ventilated children in the operating room

Background and aim

Point-of-care ultrasound imaging of the inferior vena cava distensibility index is a potential indicator for determining fluid overload and dehydration in the mechanically ventilated patients. Data on inferior vena cava distensibility index and inferior vena cava distensibility variability are limited in mechanically ventilated pediatric patients. That is why our aim in this study was to measure inferior vena cava distensibility index and to obtain mean values in pediatric patients, ventilated in the operating room before the ambulatory surgical procedure started.

Materials and methods

This crosssectional study was performed between February 2019 and February 2020. Ultrasonographic measurements were performed in a total of 125 children.

Results

In a period of 13 months, the measurements were performed in a total of 125 children, of which 120 (62.5% male) met the criteria and were included in the study. Overall inferior vena cava distensibility index (%): mean ± SD: 6.8 ± 4.0, median (min–max): 5.7 (1.4–19.6), IQR: 3.8–8.7. Overall inferior vena cava distensibility variability (%): mean ± SD: 6.5 ± 3.7, median (min–max): 5.5 (1.4–17.8), IQR: 3.7–8.4.

Conclusion

Our study is the largest series of children in the literature in which inferior vena cava distensibility index measurements were investigated.

Pleth variability index may predict preload responsiveness in patients treated with nasal high flow: a physiological study

The purpose of this study was to determine whether the plethysmographic variability index ("PVi") can predict preload responsiveness in patients with nasal high flow (NHF) (≥30 L/min) with any sign of hypoperfusion. "Preload responsiveness" was defined as a ≥10% increase in stroke volume (SV), measured by transthoracic echocardiography, after passive leg raising. SV and PVi were reassessed in preload responders after receiving a 250-mL fluid challenge. Twenty patients were included and 12 patients (60%) were preload responders. Responders showed higher baseline mean PVi (24% vs. 13%; P = 0.001) and higher mean PVi variation (ΔPVi) after passive leg raising (6.8% vs. -1.7%; P < 0.001). No differences between mean ΔPVi after passive leg raising and mean ΔPVi after fluid challenge were observed (6.8% vs. 7.4%; P = 0.24); and both values were strongly correlated (r = 0.84; P < 0.001). Baseline PVi and ΔPVi after passive leg raising showed excellent diagnostic accuracy identifying preload responders (AUROC 0.92 and 1.00, respectively). Baseline PVi ≥ 16% had a sensitivity of 91.7% and a specificity of 87.5% for detecting preload responders. Similarly, ΔPVi after passive leg raising ≥2% had a 100% of both sensitivity and specificity. Thus, PVi might predict "preload responsiveness" in patients treated with NHF, suggesting that it may guide fluid administration in these patients.NEW & NOTEWORTHY This is the first study that analyzes the use of noninvasive plethysmographic variability index (PVi) for preload assessment in patients treated with nasal high flow (NHF). Its results showed that PVi might identify preload responders. Therefore, PVi may be used in the day-to-day clinical decision-making process in critically ill patients treated with NHF, helping to provide adequate resuscitation volume.

Left-Sided Ventricular-arterial Coupling and Volume Responsiveness in Septic Shock Patients

BACKGROUND

Suboptimal ventricular arterial coupling (VAC) is one of the pivotal determinants of inefficient heart performance despite appropriate administration of fluids or vasopressors in shocks. Here, we investigate the performance of VAC in patients who are unresponsive to fluid administration in septic shock.

METHODS

This is a retrospective observational study of septic shock patients (n = 35). VAC was evaluated by effective arterial elastance (EaI), left ventricular end-systolic elastance (EesI), and EaI/EesI. Septic shock patients successfully fluid resuscitated after pulse indicator continuous cardiac output (PiCCO) monitoring, defined as an increase in general end-diastolic ventricular volume (GEDVI) more than 10%, were divided into volume responsive (VVr), and volume unresponsive (VVur) groups based on a cardiac index increase above 10%. We hypothesize that two groups of patients will exhibit dissimilarities of VAC variation, defined as EaI/EesI variation (ΔEaI/EesI).

RESULTS

Variations of EaI (ΔEaI), and EaI/EesI (ΔEaI/EesI), and systemic vascular resistance index (ΔSVRI) were significantly lower in the VVr group than those in the VVur group (P < 0.05). Variations of cardiac index (ΔCI), stroke volume index (ΔSVI), and EesI (ΔEesI) were significantly higher in patients with ΔEaI/EesI ≤ 0. Concomitantly, ΔEaI and ΔSVRI were significantly diminished as compared with patients with ΔEaI/EesI > 0 (P < 0.05). ΔCI has an inverse relationship with both ΔEaI (r = -0.46, P = 0.006), ΔEaI/EesI (r = -0.65, P < 0.001), and ΔSVRI (r = -0.59, P < 0.001). We observed more patients who were fluid responsive in the ΔEaI/EesI ≤ 0 group than in the group with ΔEaI/EesI > 0 (88.89% vs. 26.92%, P = 0.01).

CONCLUSIONS

Variation of VAC is often related to suboptimal ventricular volume responsiveness among patients with septic shock.

Perfusion indices can predict early volume depletion in a blood donor model

INTRODUCTION

Blood donation from healthy donors is used experimental model that surrogates for class 1 hemorrhage in humans. We examined changes in the perfusion index (PI) and plethysmographic variability index (PVI) in healthy blood donors after donating a unit of blood, and we evaluated the usability of these indices in detecting blood loss volumes of less than 750 mL (class 1 hemorrhagic shock trauma patients).

MATERIALS AND METHODS

This study is a prospective, cross-sectional study. 180 healthy volunteers aged 18 and over, who donated blood at the local blood bank, were included in the study consecutively. The age, gender, and body mass index of the volunteers were recorded and, before and after the blood donation, the vital signs and perfusion indices were measured.

RESULTS

Of the donors, 61.7% were men (n = 111), and the median age of all donors was 32 (IQR: 21-39). A statistically significant difference was found between the hemodynamic parameters and PIs before and after the blood donation (p < 0.01 for all parameters; median difference of PI [- 1.45, 95% CI: (- 0.9)-( - 2)], median difference of PVI [6, 95% CI: 7.77-4.23].

CONCLUSION

We evaluated the perfusion indices in the early diagnosis of blood volume loss in patients admitted to the emergency department due to trauma. After the participants donated one unit of blood, we found that their PI decreased and PVI increased compared to the measurements before the blood donation. Considering that major bleeding starts in the very early stage as minor bleeding, it is essential for emergency physicians to recognize class 1 hemorrhagic shock patients. Further, non-invasive and straightforward procedures, such as measuring PI and PVI, can be particularly useful in identifying blood loss volumes of less than 750 mL.

Reliability of pleth variability index in predicting preload responsiveness of mechanically ventilated patients under various conditions: a systematic review and meta-analysis

Background

Goal-directed volume expansion is increasingly used for fluid management in mechanically ventilated patients. The Pleth Variability Index (PVI) has been shown to reliably predict preload responsiveness; however, a lot of research on PVI has been published recently, and update of the meta-analysis needs to be completed.

Methods

We searched PUBMED, EMBASE, Cochrane Library, Web of Science (updated to November 7, 2018) and the associated references. Relevant authors and researchers had been contacted for complete data.

Results

Twenty-five studies with 975 mechanically ventilated patients were included in this meta-analysis. The area under the curve (AUC) of receiver operating characteristics (ROC) to predict preload responsiveness was 0.82 (95% confidence interval (CI) 0.79–0.85). The pooled sensitivity was 0.77 (95% CI 0.67–0.85) and the pooled specificity was 0.77 (95% CI 0.71–0.82). The results of subgroup of patients without undergoing surgery (AUC =0.86, Youden index =0.65) and the results of subgroup of patients in ICU (AUC =0.89, Youden index =0.67) were reliable.

Conclusion

The reliability of the PVI is limited, but the PVI can play an important role in bedside monitoring for mechanically ventilated patients who are not undergoing surgery. Patients who are expanded with colloid may be more suitable for PVI.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0744-4) contains supplementary material, which is available to authorized users.

The plethysmographic variability index does not predict fluid responsiveness estimated by esophageal Doppler during kidney transplantation: A controlled study

Research is ongoing to find a noninvasive method of monitoring, which can predict fluid responsiveness in patients undergoing kidney transplantation.To compare the responses to fluid challenges with the Pleth Variability Index, a noninvasive dynamic index derived from plethysmographic variability (Radical 7 pulse oximeter; Masimo Corporation, Irvine, CA), and the esophageal Doppler, the criterion standard.Observational study.University hospital; study from May 2011 and May 2012.Forty-eight patients with end-renal function were included and 44 analyzed. Patients with cardiac failure were not eligible.Fluid challenges were administered during maintenance of general anesthesia but before skin incision and repeated if the patient was deemed to be a "responder" (increase in stroke volume ≥10%).The primary endpoint was to assess if the Pleth Variability Index is an accurate predictor of fluid responsiveness.Among 76 fluid challenges, 38 were considered as positive (increase in stroke volume measured by Doppler ≥10%). Pleth Variability Index was similar at baseline between responders and nonresponder patients. Fluid challenges were associated with a significant decrease in Pleth Variability Index in overall cases (12 [8-14] vs 10 [6-17], P = .050), but it was not able to discriminate between responders (12 [8-15] vs 10 [5-15], P = .650) and nonresponders (11 [6-16] vs 8 [5-14], P = .047). The area under the Receiver Operating Characteristic curve for Pleth Variability Index was 0.49 (0.36-0.62).Pleth Variability Index is not an accurate predictor of fluid responsiveness during kidney transplantation.

The Assessment of Intravascular Volume with Inferior Vena Cava and Internal Jugular Vein Distensibility Indexes in Children Undergoing Urologic Surgery

PURPOSE

The purpose of this work is to assess the predictive value, for fluid responsiveness (FR), of the inferior vena cava distensibility index (IVC-DI) and internal jugular vein distensibility index (IJV-DI) in pediatric surgical patients.

MATERIAL AND METHODS

Prior to being placed under general anesthesia, 24 surgical patients were enrolled. Baseline parameters were recorded with the patient in the semirecumbent position (Stage 1). Next, the passive leg raising (PLR) maneuver was carried out and a second measurement was recorded (Stage 2). Patients with an increase in the cardiac index (CI) of >10%, induced by PLR, were considered to be responders (R), otherwise they were classified as nonresponders (NR). At both stages, CI and DI of the IVC and IJV were measured.

RESULTS

Responders had higher IVC-DI and IVJ-DI than NR in stage 1 (both p <.001). In stage 2, IVC-DI and IJV-DI were not different in R and NR groups (p =.164, p =.201). Utilizing cut-off values of > 22.7% for IVC-DI and > 25% for IJV-DI, these parameters had positive correlation coefficients, both in R and NR of, respectively, 0.626 and 0.929.

CONCLUSIONS

The IVC-DI predicts FR in anesthetized pediatric patients and correlates well with the IJV-DI; both may be used as prediction markers of FR in children.

A review of hemodynamic monitoring techniques, methods and devices for the emergency physician

The emergency department (ED) is frequently the doorway to the intensive care unit (ICU) for a significant number of critically ill patients presenting to the hospital. Hemodynamic monitoring (HDM) which is a key component in the effective management of the critically ill patient presenting to the ED, is primarily concerned with assessing the performance of the cardiovascular system and determining the correct therapeutic intervention to optimise end-organ oxygen delivery. The spectrum of hemodynamic monitoring ranges from simple clinical assessment and routine bedside monitoring to point of care ultrasonography and various invasive monitoring devices. The clinician must be aware of the range of available techniques, methods, interventions and technological advances as well as possess a sound approach to basic hemodynamic monitoring prior to selecting the optimal modality. This article comprises an in depth discussion of an approach to hemodynamic monitoring techniques and principles as well as methods of predicting fluid responsiveness as it applies to the ED clinician. We review the role, applicability and validity of various methods and techniques that include; clinical assessment, passive leg raising, blood pressure, finger based monitoring devices, the mini-fluid challenge, the end-expiratory occlusion test, central venous pressure monitoring, the pulmonary artery catheter, ultrasonography, bioreactance and other modern invasive hemodynamic monitoring devices.

The haemodynamic dilemma in emergency care: Is fluid responsiveness the answer? A systematic review

BACKGROUND

Fluid therapy is a common and crucial treatment in the emergency department (ED). While fluid responsiveness seems to be a promising method to titrate fluid therapy, the evidence for its value in ED is unclear. We aim to synthesise the existing literature investigating fluid responsiveness in ED.

METHODS

MEDLINE, Embase and the Cochrane library were searched for relevant peer-reviewed studies published from 1946 to present.

RESULTS

A total of 249 publications were retrieved of which 22 studies underwent full-text review and eight relevant studies were identified. Only 3 studies addressed clinical outcomes - including 2 randomised controlled trials and one feasibility study. Five articles evaluated the diagnostic accuracy of fluid responsiveness techniques in ED. Due to marked heterogeneity, it was not possible to combine results in a meta-analysis.

CONCLUSION

High quality, adequately powered outcome studies are still lacking, so the place of fluid responsiveness in ED remains undefined. Future studies should have standardisation of patient groups, the target response and the underpinning theoretic concept of fluid responsiveness. The value of a fluid responsiveness based fluid resuscitation protocol needs to be established in a clinical trial.

Evidence-based fluid management in the ICU

PURPOSE OF REVIEW

Evidence-based fluid therapy is complicated by blurred boundaries toward other fields of therapy and the majority of trials not focusing on patient-relevant outcomes. Additionally, recent trials unsettled the faith in traditional concepts on fluid therapy. The article reviews the evidence on diagnosis and treatment of hypovolemia and discusses the use of balanced solutions and early goal-directed therapy (EGDT) in septic shock resuscitation.

RECENT FINDINGS

Hypovolemia should be diagnosed and its treatment guided by a multifaceted approach, including medical history, physical examination, volume responsiveness, and technical parameters - dynamic indicators, volumetric indicators, sonography, and metabolic indicators. Central venous pressure and pulmonary artery occlusion pressure should be avoided. In ICU patients, balanced crystalloids should primarily be used, because unbalanced infusions (especially saline) cause hyperchloremic acidosis which is associated with renal impairment and infections. Colloids are beneficial to restore blood volume rapidly. Hydroxyethyl starch may be harmful although the validity of the respective recent studies is limited by methodological flaws. Early aggressive fluid therapy is still beneficial in septic shock resuscitation, despite recent trials challenging the EGDT concept. Today, 10 years after Rivers, 'usual care' includes aggressive fluid resuscitation that is as effective as formal EGDT.

SUMMARY

Evidence-based fluid therapy includes a multifaceted diagnostic approach, the primary use of balanced crystalloids and early aggressive (septic) shock resuscitation.

Pulse Wave Transit Time Measurements of Cardiac Output in Septic Shock Patients: A Comparison of the Estimated Continuous Cardiac Output System with Transthoracic Echocardiography

Background

We determined reliability of cardiac output (CO) measured by pulse wave transit time cardiac output system (esCCO system; CO_esCCO) vs transthoracic echocardiography (CO_TTE) in mechanically ventilated patients in the early phase of septic shock. A secondary objective was to assess ability of esCCO to detect change in CO after fluid infusion.

Methods

Mechanically ventilated patients admitted to the ICU, aged >18 years, in sinus rhythm, in the early phase of septic shock were prospectively included. We performed fluid infusion of 500ml of crystalloid solution over 20 minutes and recorded CO by EsCCO and TTE immediately before (T0) and 5 minutes after (T1) fluid administration. Patients were divided into 2 groups (responders and non-responders) according to a threshold of 15% increase in CO_TTE in response to volume expansion.

Results

In total, 25 patients were included, average 64±15 years, 15 (60%) were men. Average SAPSII and SOFA scores were 55±21.3 and 13±2, respectively. ICU mortality was 36%. Mean cardiac output at T0 was 5.8±1.35 L/min by esCCO and 5.27±1.17 L/min by CO_TTE. At T1, respective values were 6.63 ± 1.57 L/min for esCCO and 6.10±1.29 L/min for CO_TTE. Overall, 12 patients were classified as responders, 13 as non-responders by the reference method. A threshold of 11% increase in CO_esCCO was found to discriminate responders from non-responders with a sensitivity of 83% (95% CI, 0.52-0.98) and a specificity of 77% (95% CI, 0.46-0.95).

Conclusion

We show strong correlation esCCO and echocardiography for measuring CO, and change in CO after fluid infusion in ICU patients.

Assessing volume status and fluid responsiveness in the emergency department

Resuscitation with intravenous fluid can restore intravascular volume and improve stroke volume. However, in unstable patients, approximately 50% of fluid boluses fail to improve cardiac output as intended. Increasing evidence suggests that excess fluid may worsen patient outcomes. Clinical examination and vital signs are unreliable predictors of the response to a fluid challenge. We review the importance of fluid management in the critically ill, methods of evaluating volume status, and tools to predict fluid responsiveness.

Photoplethysmography

The photoplethysmographic (PPG) waveform, also known as the pulse oximeter waveform, is one of the most commonly displayed clinical waveforms. First described in the 1930s, the technology behind the waveform is simple. The waveform, as displayed on the modern pulse oximeter, is an amplified and highly filtered measurement of light absorption by the local tissue over time. It is optimized by medical device manufacturers to accentuate its pulsatile components. Physiologically, it is the result of a complex, and not well understood, interaction between the cardiovascular, respiratory, and autonomic systems. All modern pulse oximeters extract and display the heart rate and oxygen saturation derived from the PPG measurements at multiple wavelengths. "As is," the PPG is an excellent monitor for cardiac arrhythmia, particularly when used in conjunction with the electrocardiogram (ECG). With slight modifications in the display of the PPG (either to a strip chart recorder or slowed down on the monitor screen), the PPG can be used to measure the ventilator-induced modulations which have been associated with hypovolemia. Research efforts are under way to analyze the PPG using improved digital signal processing methods to develop new physiologic parameters. It is hoped that when these new physiologic parameters are combined with a more modern understanding of cardiovascular physiology (functional hemodynamics) the potential utility of the PPG will be expanded. The clinical researcher's objective is the use of the PPG to guide early goal-directed therapeutic interventions (fluid, vasopressors, and inotropes), in effect to extract from the simple PPG the information and therapeutic guidance that was previously only obtainable from an arterial pressure line and the pulmonary artery catheter.