Fluid responsiveness in acute circulatory failure

Traumatic brain injury: Symptoms to systems in the 21st century

Severe traumatic brain injury (TBI) is a devastating injury with a mortality of ∼ 25-30 %. Despite decades of high-quality research, no drug therapy has reduced mortality. Why is this so? We argue two contributing factors for the lack of effective drug therapies include the use of specific-pathogen free (SPF) animals for translational research and the flawed practice of single-nodal targeting for drug design. A revolution is required to better understand how the whole body responds to TBI, identify new markers of its progression, and discover new system-acting drugs to treat it. In this review, we present a brief history of TBI, discuss its system's pathophysiology and propose a new research strategy for the 21st century. TBI progression develops from injury signals radiating from the primary impact, which can cause local ischemia, hemorrhage, excitotoxicity, cellular depolarization, immune dysfunction, sympathetic hyperactivity, blood-brain barrier breach, coagulopathy and whole-body dysfunction. Metabolic reprograming of immune cells drives neuroinflammation and secondary injury processes. We propose if sympathetic hyperactivity and immune cell activation can be corrected early, cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored, and secondary injury minimized with improved patient outcomes. The therapeutic goal is to switch the injury phenotype to a healing phenotype by restoring homeostasis and maintaining sufficient tissue O2 delivery. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine and magnesium (ALM) to treat TBI and have shown that it blunts the CNS-stress response, supports cardiovascular function and reduces secondary injury. Future research will investigate its suitability for human translation.

Pathophysiology of Severe Burn Injuries: New Therapeutic Opportunities From a Systems Perspective

Severe burn injury elicits a profound stress response with the potential for high morbidity and mortality. If polytrauma is present, patient outcomes appear to be worse. Sex-based comparisons indicate females have worse outcomes than males. There are few effective drug therapies to treat burn shock and secondary injury progression. The lack of effective drugs appears to arise from the current treat-as-you-go approach rather than a more integrated systems approach. In this review, we present a brief history of burns research and discuss its pathophysiology from a systems' perspective. The severe burn injury phenotype appears to develop from a rapid and relentless barrage of damage-associated molecular patterns, pathogen-associated molecular patterns, and neural afferent signals, which leads to a state of hyperinflammation, immune dysfunction, coagulopathy, hypermetabolism, and intense pain. We propose that if the central nervous system control of cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored early, these secondary injury processes may be minimized. The therapeutic goal is to switch the injury phenotype to a healing phenotype by reducing fluid leak and maintaining tissue O2 perfusion. Currently, no systems-based therapies exist to treat severe burns. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine, and magnesium (ALM) to treat hemorrhagic shock, traumatic brain injury, and sepsis. Our early studies indicate that the ALM therapy holds some promise in supporting cardiovascular and pulmonary functions following severe burns. Future research will investigate the ability of ALM therapy to treat severe burns with polytrauma and sex disparities, and potential translation to humans.

Prediction of fluid responsiveness in spontaneously breathing patients with hemodynamic stability: a prospective repeated-measures study

Evaluating fluid responsiveness with dynamic parameters is recommended for fluid management. However, in hemodynamically stable patients who are breathing spontaneously, accurately measuring stroke volume variation via echocardiography and passive leg raising is challenging due to subtle SV changes. This study aimed to identify normal SV changes in healthy volunteers and evaluate the precision of hemodynamic parameters in screening mild hypovolemia in patients. This prospective, repeated-measures, cross-sectional study screened 269 subjects via echocardiography. Initially, 45 healthy volunteers underwent a fluid challenge test, the outcomes of which served as criteria to screen 215 ICU patients. Among these patients, 53 underwent additional fluid challenge testing. Hemodynamic parameters, including medians of maximum velocity time integrals (VTImaxs), peak velocity of VTImax (PV), internal jugular vein diameters (IJVD), and area (IJVA) were repeatedly measured first at a 60° upper body elevation (UBE), second in a supine position, third at UBE, fourth in a supine position, and lastly in a supine position after fluid loading. The hemodynamic responses to the position changes were compared between 83 fluid non-responders and 15 fluid responders. Fluid responsiveness was defined as fluid-induced medians' change of VTImaxs (fluid-induced median VTImax change) ≥ 10%. None of the healthy volunteers showed the mean value of repeatedly measured medians of VTImaxs ≥ 7%, following either UBE position (UBE-induced median VTImax change) or fluid loading (fluid-induced median VTImax change). UBE-induced median VTImax and PV changes were significantly correlated with fluid responsiveness (p < 0.001, AUC 0.959; p < 0.001, AUC 0.804). The significant correlations were demonstrated via multivariable analysis using binary logistic regression (p = 0.001, OR 90.1) and the correlation coefficient (R2 = 0.793) using linear regression analysis. UBE-induced median VTImax changes (≥ 11.8% and 7.98%) predicted fluid-induced median VTImax changes ≥ 10% and 7% (AUC 0.959 and 0.939). The collapsibility and variation of IJVD and IJVA showed no significant correlation. An increase in the mean value of medians of repeatedly measured VTImaxs transitioning from an UBE to a supine position, effectively screened mild hypovolemia and demonstrated a significant correlation with fluid responsiveness in spontaneously breathing patients maintaining hemodynamic stability.

Revolution in sepsis: a symptoms-based to a systems-based approach?

Severe infection and sepsis are medical emergencies. High morbidity and mortality are linked to CNS dysfunction, excessive inflammation, immune compromise, coagulopathy and multiple organ dysfunction. Males appear to have a higher risk of mortality than females. Currently, there are few or no effective drug therapies to protect the brain, maintain the blood brain barrier, resolve excessive inflammation and reduce secondary injury in other vital organs. We propose a major reason for lack of progress is a consequence of the treat-as-you-go, single-nodal target approach, rather than a more integrated, systems-based approach. A new revolution is required to better understand how the body responds to an infection, identify new markers to detect its progression and discover new system-acting drugs to treat it. In this review, we present a brief history of sepsis followed by its pathophysiology from a systems' perspective and future opportunities. We argue that targeting the body's early immune-driven CNS-response may improve patient outcomes. If the barrage of PAMPs and DAMPs can be reduced early, we propose the multiple CNS-organ circuits (or axes) will be preserved and secondary injury will be reduced. We have been developing a systems-based, small-volume, fluid therapy comprising adenosine, lidocaine and magnesium (ALM) to treat sepsis and endotoxemia. Our early studies indicate that ALM therapy shifts the CNS from sympathetic to parasympathetic dominance, maintains cardiovascular-endothelial glycocalyx coupling, reduces inflammation, corrects coagulopathy, and maintains tissue O2 supply. Future research will investigate the potential translation to humans.

Comparison Between Changes in Systolic-Pressure Variation and Pulse-Pressure Variation After Passive Leg Raising to Predict Fluid Responsiveness in Postoperative Critically Ill Patients

OBJECTIVE

The authors aimed to evaluate the precision of changes in systolic-pressure variation after passive leg raising (PLR) as a predictor of fluid responsiveness in postoperative critically ill patients, and to compare the precision of changes in pulse-pressure variation after PLR (ΔPPVPLR) with changes in systolic-pressure variation after PLR (ΔSPVPLR).

DESIGN

A prospective observational study.

SETTING

A surgical intensive care unit of a tertiary hospital.

PARTICIPANTS

Seventy-four postoperative critically ill patients with acute circulatory failure were enrolled.

INTERVENTIONS

Fluid responsiveness was defined as an increase of 10% or more in stroke volume after PLR, dividing patients into 2 groups: responders and nonresponders.

MEASUREMENT AND MAIN RESULTS

Hemodynamic data were recorded at baseline and after PLR, and the stroke volume was measured by transthoracic echocardiography. Thirty-eight patients were responders, and 36 were nonresponders. ΔPPVPLR predicted fluid responsiveness with an area under the receiver operating characteristic curve (AUC) of 0.917, and the optimal cutoff value was 2.3%, with a gray zone of 1.6% to 3.3%, including 19 (25.7%) patients. ΔSPVPLR predicted fluid responsiveness with an AUC of 0.908, and the optimal cutoff value was 1.9%, with a gray zone of 1.1% to 2.0%, including 18 (24.3%) patients. No notable distinction was observed between the AUC for ΔPPVPLR and ΔSPVPLR (p = 0.805) in predicting fluid responsiveness.

CONCLUSIONS

ΔSPVPLR and ΔPPVPLR could accurately predict fluid responsiveness in postoperative critically ill patients. There was no difference in the ability to predict fluid responsiveness between ΔSPVPLR and ΔPPVPLR.

THE ACCURACY OF INFERIOR VENA CAVA DISTENSIBILITY THROUGH THE TRANSHEPATIC APPROACH TO PREDICT FLUID RESPONSIVENESS IN PATIENTS WITH SEPTIC SHOCK AFTER EMERGENCY LAPAROTOMY

ABSTRACT

Background: We aimed to evaluate the ability of inferior vena cava (IVC) distensibility using the transhepatic approach to predict fluid responsiveness in mechanically ventilated patients with septic shock after emergency laparotomy. Methods: This prospective observational study included mechanically ventilated paralyzed adult who had septic shock after emergency laparotomy. The IVC dimensions were measured through the transhepatic and subxiphoid approaches. The fluid responsiveness was confirmed with >15% increase in cardiac output after 500 mL of fluid bolus. The outcomes were the ability of transhepatic (primary outcome) and subxiphoid approach to predict fluid responders using the area under the receiver operating characteristics curve analysis. The gray zone for the two approaches was calculated. Results: Data from 51 patients were analyzed, and the number of fluid responders was 30 of 52 (58%). The transhepatic approach was feasible in all patients, whereas the subxiphoid approach was only feasible in 42 patients. The area under the receiver operating characteristics curve (95% confidence interval) for the transhepatic IVC distensibility was 0.88 (0.76-0.95), and it was comparable with that of the subxiphoid approach (0.81 [0.66-0.92], P = 0.417). The gray zone for the transhepatic IVC distensibility was 17% to 35% including 24 of 51 patients (47%), whereas the gray zone for the subxiphoid IVC distensibility was 13% to 34% including 18 of 42 patients (43%). Conclusion: In conclusion, the transhepatic approach for evaluation of IVC distensibility showed good accuracy in predicting fluid responsiveness in patients with septic shock after emergency laparotomy. The transhepatic approach showed the same accuracy as the subxiphoid approach with the advantage of being feasible in larger number of patients.

Central venous pressure and dynamic indices to assess fluid appropriateness in critically ill patients: A pilot study

BACKGROUND

The correct identification of the appropriateness of fluid administration is important for the treatment of critically ill patients. Static and dynamic indices used to identify fluid responsiveness have been developed throughout the years, nonetheless fluid responsiveness does not indicate that fluid administration is appropriate, and indexes to evaluate appropriateness of fluid administration are lacking. The aim of this study was to evaluate if central venous pressure (CVP) anddynamic indices could correctly identify fluid appropriateness for critically ill patients.

METHODS

Data from 31 ICU patients, for a total of 53 observations, was included in the analysis. Patients were divided into two cohorts based on the appropriateness of fluid administration. Fluid appropriateness was defined in presence of a low cardiac index (< 2.5 l/min/m2) without any sign of fluid overload, as assessed by global end-diastolic volume index, extravascular lung water index or pulmonary artery occlusion pressure.

RESULTS

For 10 patients, fluid administration was deemed appropriate, while for 21 patients it was deemed inappropriate. Central venous pressure was not different between the two cohorts (mean CVP 11 (4) mmHg in the fluid inappropriate group, 12 (4) mmHg in the fluid appropriate group, p 0.58). The same is true for pulse pressure variation (median PPV 5 [2, 9] % in the fluid inappropriate group, 4 [3, 13] % in the fluid appropriate group, p 0.57), for inferior vena cava distensibility (mean inferior vena cava distensibility 24 (14) % in the fluid inappropriate group, 22 (16) % in the fluid appropriate group, p 0.75) and for changes in end tidal carbon dioxide during a passive leg raising test (median d.ETCO2 1.5 [0.0, 2.0]% in the fluid inappropriate group, 1.0 [0.0, 2.0] % in the fluid appropriate group, p 0.98). There was no association between static and dynamic indices and fluid appropriateness.

CONCLUSIONS

Central venous pressure, pulse pressure variation, changes in end tidal carbon dioxide during a passive leg raising test, inferior vena cava distensibility were not associated with fluid appropriateness in our cohorts.

Ketamine-based Versus Fentanyl-based Regimen for Rapid-sequence Endotracheal Intubation in Patients with Septic Shock: A Randomised Controlled Trial

Objective

The aim of this work is to compared ketamine-based versus fentanyl-based regimens for endotracheal intubation in patients with septic shock undergoing emergency surgery.

Design

This was a randomised double-blinded controlled trial.

Participants

Patients with septic shock on norepinephrine infusion scheduled for emergency surgery.

Setting and Interventions

At induction of anaesthesia, patients were allocated into ketamine group (n=23) in which the participants received ketamine 1 mg/kg, and fentanyl group (n=19) in which the participants received fentanyl 2.5 mcg/ kg. Both groups received midazolam (0.05 mg/kg) and succinyl choline (1 mg/kg).

Measurement

The primary outcome was mean arterial blood pressure. The secondary outcomes included: heart rate, cardiac output, and incidence of postintubation hypotension defined as mean arterial pressure ≤80% of baseline value.

Results

Forty-two patients were available for final analysis. The mean blood pressure was higher in the ketamine group than in the fentanyl group at 1, 2 and 5 minutes after the induction of anaesthesia. Furthermore, the incidence of postinduction hypotension was lower in the ketamine group than in the fentanyl group (11 [47.8%] versus 16 [84.2%], P-value= 0.014). Other hypodynamic parameters, namely the heart rate and cardiac output, were comparable between both groups; and were generally maintained in relation to the baseline reading in each group.

Conclusion

The ketamine-based regimen provided better hemodynamic profile compared to fentanyl-based regimen for rapid-sequence intubation in patients with septic shock undergoing emergency surgery.

Potential of Medical Management to Mitigate Suction Events in Ventricular Assist Device Patients

Ventricular suction is a common adverse event in ventricular assist device (VAD) patients and can be due to multiple underlying causes. The aim of this study is to analyze the potential of different therapeutic interventions to mitigate suction events induced by different pathophysiological conditions. To do so, a suction module was embedded in a cardiovascular hybrid (hydraulic-computational) simulator reproducing the entire cardiovascular system. An HVAD system (Medtronic) was connected between a compliant ventricular apex and a simulated aorta. Starting from a patient profile with severe dilated cardiomyopathy, four different pathophysiological conditions leading to suction were simulated: hypovolemia (blood volume: -900 ml), right ventricular failure (contractility -70%), hypotension (systemic vascular resistance: 8.3 Wood Units), and tachycardia (heart rate:185 bpm). Different therapeutic interventions such as volume infusion, ventricular contractility increase, vasoconstriction, heart rate increase, and pump speed reduction were simulated. Their effects were compared in terms of general hemodynamics and suction mitigation. Each intervention elicited a different effect on the hemodynamics for every pathophysiological condition. Pump speed reduction mitigated suction but did not ameliorate the hemodynamics. Administering volume and inducing a systemic vasoconstriction were the most efficient interventions in both improving the hemodynamics and mitigating suction. When simulating volume infusion, the cardiac powers increased, respectively, by 38%, 25%, 42%, and 43% in the case of hypovolemia, right ventricular failure, hypotension, and tachycardia. Finally, a management algorithm is proposed to identify a therapeutic intervention suited for the underlying physiologic condition causing suction.

Efficacy of using tidal volume challenge to improve the reliability of pulse pressure variation reduced in low tidal volume ventilated critically ill patients with decreased respiratory system compliance

Background

The prediction accuracy of pulse pressure variation (PPV) for fluid responsiveness was proposed to be unreliable in low tidal volume (Vt) ventilation. It was suggested that changes in PPV obtained by transiently increasing Vt to 8 ml/kg accurately predicted fluid responsiveness even in subjects receiving low Vt. We assessed whether the changes in PPV induced by a Vt challenge predicted fluid responsiveness in our critically ill subjects ventilated with low Vt 6 ml/kg.

Methods

This study is a prospective single-center study. PPV and other parameters were measured at a Vt of 6 mL/kg, 8 mL/kg, and after volume expansion. The prediction accuracy of PPV and other parameters for fluid responsiveness before and after tidal volume challenge was also analyzed using receiver operating characteristic (ROC) curves.

Results

Thirty-one of the 76 subjects enrolled in the study were responders (41%). Respiratory system compliance of all subjects decreased significantly (26 ± 4.3). The PPV values were significantly higher in the responder group than the non-responder group before (8.8 ± 2.7 vs 6.8 ± 3.1) or after (13.0 ± 1.7 vs 8.5 ± 3.0) Vt challenge. In the receiver operating characteristic curve (ROC) analysis, PPV₆ showed unsatisfactory predictive capability with an area under the curve (AUC) of 0.69 (95%CI, 0.57–0.79, p = 0.002) at a Vt of 6 mL/kg. PPV₈ andΔPPV_6–8 showed good predictive capability with an AUC of 0.90 (95% CI, 0.81–0.96, p < 0.001) and 0.90 (95% CI, 0.80–0.95, P < 0.001) respectively. The corresponding cutoff values were 11% for PPV₈ and 2% for ΔPPV_6–8.

Conclusions

PPV shows a poor operative performance as a predictor of fluid responsiveness in critically ill subjects ventilated with a tidal volume of 6 mL/ kg. Vt challenge could improve the predictive accuracy of PPV to a good but not excellent extent when respiratory system compliance decreased significantly.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01676-8.

Accuracy of oscillometric blood pressure measurement at both arms in the lateral position

PURPOSE

To evaluate the accuracy of noninvasive blood pressure (NIBP) measurement at the dependent- and nondependent arms in the lateral position, using invasive blood pressure (IBP) as reference.

METHODS

This prospective observational study included 42 adult patients undergoing surgery in the lateral position. Paired readings of IBP and NIBP were obtained at either arm. The accuracy of both arms in detecting mean arterial pressure (MAP) <70 mmHg was evaluated using the area under the receiver operating characteristic curve (AUC). The agreement between the IBP and NIBP was evaluated using the Bland-Altman and error grid analyses.

RESULTS

We analyzed 350 and 347 paired readings at the dependent- and nondependent arms. The AUC for detecting hypotension was comparable in both arms. The negative and positive predictive values (95% confidence interval) were 100% (99-100%) and 24% (14-34%), respectively for the dependent arm at cutoff value MAP ≤86 mmHg; and were 99% (96-100%) and 21% (13-30%), respectively for the nondependent arm at cutoff value MAP ≤75 mmHg. The mean bias for MAP was -6.0 ± 9.1 and 6.3 ± 10.1 mmHg; and for systolic blood pressure was 0.3 ± 11.6 and 13.2 ± 12.6 mmHg, in the dependent- and nondependent arm, respectively. Error grid analysis showed that the proportions of paired MAP readings in risk zone A were 71 and 82% in the dependent- and the nondependent arms, respectively.

CONCLUSION

In the lateral position, the NIBP readings at both arms are not interchangeable with the corresponding IBP readings. However, NIBP measurement at both arms can be used to accurately rule out hypotension.

The ability of pulse oximetry-derived peripheral perfusion index to detect fluid responsiveness in patients with septic shock

BACKGROUND

Fluid challenge test is a widely used method for the detection of fluid responsiveness in acute circulatory failure. However, detection of the patient's response to the fluid challenge requires monitoring of cardiac output which is not feasible in many settings. We investigated whether the changes in the pulse oximetry-derived peripheral perfusion index (PPI), as a non-invasive surrogate of cardiac output, can detect fluid responsiveness using the fluid challenge test or not.

METHODS

We prospectively enrolled 58 patients with septic shock on norepinephrine infusion. Fluid challenge test, using 200 mL crystalloid solution, was performed in all study subjects. All patients received an additional 300 mL crystalloid infusion to confirm fluid responsiveness. Velocity time integral (VTI) (using transthoracic echocardiography), and PPI were measured at the baseline, after 200 mL fluid challenge, and after completion of 500 mL crystalloids. Fluid responsiveness was defined by 10% increase in the VTI after completion of the 500 mL. The predictive ability of ∆PPI [Calculated as (PPI after 200 mL - baseline PPI)/baseline PPI] to detect fluid responders was obtained using the receiver operating characteristic curve.

RESULTS

Forty-two patients (74%) were fluid responders; in whom, the mean arterial pressure, the central venous pressure, the VTI, and the PPI increased after fluid administration compared to the baseline values. ∆PPI showed moderate ability to detect fluid responders [area under receiver operating characteristic curve (95% confidence interval) 0.82 (0.70-0.91), sensitivity 76%, specificity 80%, positive predictive value 92%, negative predictive value 54%, cutoff value ≥ 5%]. There was a significant correlation between ∆PPI and ∆VTI induced by the fluid challenge.

CONCLUSION

∆PPI showed moderate ability to detect fluid responsiveness in patients with septic shock on norepinephrine infusion. Increased PPI after 200 mL crystalloid challenge can detect fluid responsiveness with a positive predictive value of 92%; however, failure of the PPI to increase does not exclude fluid responsiveness.

CLINICAL TRIAL IDENTIFIER

NCT03805321. Date of registration: 15 January 2019. Clinical trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03805321?term=ahmed+hasanin&rank=9 .

Comparison of Changes in PPV Using a Tidal Volume Challenge with a Passive Leg Raising Test to Predict Fluid Responsiveness in Patients Ventilated Using Low Tidal Volume

Background

Tidal volume challenge pulse pressure variation (TVC-PPV) is considered one of the recent reliable dynamic indices of fluid responsiveness (FR); also, passive leg raising (PLR)-induced changes in cardiac output (CO) detected by echocardiography are considered a reliable reversible self-fluid challenge test; many patients share eligibility for both tests.

Objectives

The study aimed to compare the sensitivity and specificity of both tests for the prediction of FR in mechanically ventilated patients with hemodynamic instability.

Methods

We studied 46 patients. Hemodynamic parameters including PPV and CO (detected by velocity time integral (VTI) using echocardiography) recorded at tidal volume (VT) of 6 mL/kg/ideal body weight (IBW) in semi-recumbent position then recorded again after one-minute increase in TV from 6 to 8 mL/kg/IBW then recorded with PLR at TV of 6 mL/kg/IBW and finally with actual volume expansion in semi-recumbent position by 4 ml/kg bolus of crystalloid solution to define actual responders with increase of cardiac output of 15% or more.

Results

Sixteen patients were responders, and thirty patients were nonresponders; responders had significant increase in PPV with TVC 6 to 8 ml/kg/IBW with best cutoff value of 3.5 with a sensitivity of 93.8% and a specificity of 93.9%. PLR test-induced changes in CO had a sensitivity of 93.9% and a specificity of 86.7% with statistically best cutoff value of 6.5% increase in CO, but sensitivity was 75% at cutoff value of 10% increase in CO. Other parameters like PPV, PPV changes with PLR test, and PPV changes with fluid expansion were less sensitive indicators.

Conclusion

FR in patients with hemodynamic instability and mechanically ventilated with low tidal volume strategy can be efficiently predicted when PPV increases more than 3.5 with tidal volume challenge and when PLR induces 6.5% increase in CO monitored through VTI method by Doppler echocardiography, and both tests are equally reliable.

How to cite this article

Elsayed AI, Selim KAW, Zaghla HE, Mowafy HE, Fakher MA. Comparison of Changes in PPV Using a Tidal Volume Challenge with a Passive Leg Raising Test to Predict Fluid Responsiveness in Patients Ventilated Using Low Tidal Volume. Indian J Crit Care Med 2021;25(6):685–690.

Hemodynamic effects of norepinephrine versus phenylephrine infusion for prophylaxis against spinal anesthesia-induced hypotension in the elderly population undergoing hip fracture surgery: a randomized controlled trial

Background

Elderly population are at increased risk of spinal anesthesia-induced hypotension increasing their risk for postoperative morbidity and mortality. This study aimed to compare the hemodynamic effects of prophylactic infusion of norepinephrine (NE) versus phenylephrine (PE) in elderly patients undergoing hip fracture surgery under spinal anesthesia.

Methods

Elderly patients scheduled for hip fracture surgery were randomized to receive either NE infusion (8 µg/min) (NE group, n = 31) or PE infusion (100 µg/min) (PE group, n = 31) after spinal anesthesia. Outcomes included mean heart rate, mean blood pressure, cardiac output, incidence of spinal anesthesia-induced hypotension, incidence of bradycardia, and incidence of hypertension.

Results

Sixty-two patients with a mean age of 71 ± 6 years were included in the final analysis (31 patients in each group). The NE group showed a higher mean heart rate and cardiac output than the PE group. The NE group had a lower incidence of reactive bradycardia (10% vs. 36%, P = 0.031) and hypertension (3% vs. 36%, P = 0.003) than the PE group. No study participant developed hypotension, and the mean blood pressure was comparable between the two groups.

Conclusions

Both NE and PE infusions effectively prevented spinal anesthesia-induced hypotension in elderly patients undergoing hip fracture surgery. However, NE provided more hemodynamic stability than PE; maintaining the heart rate, higher cardiac output, less reactive bradycardia, and hypertension.

The benefit of adding lidocaine to ketamine during rapid sequence endotracheal intubation in patients with septic shock: A randomised controlled trial

BACKGROUND

Patients with septic shock commonly require endotracheal intubation under general anaesthesia in the operating theatre, the emergency department, and the intensive care unit. Hypotension is a serious complication after induction of general anaesthesia, especially in patients with circulatory failure. No randomised controlled trials had previously investigated protocols for induction of anaesthesia in septic shock patients. The aim of the current work is to compare two protocols, lidocaine-ketamine combination versus ketamine full-dose for rapid-sequence endotracheal intubation in patients with septic shock.

METHODS

Forty-four adult patients, with septic shock, scheduled for emergency surgical intervention were enrolled in this randomised, double-blinded, controlled study. Patients were randomised to receive either 1 mg/kg ketamine (ketamine group, n = 22) or 0.5 mg/kg ketamine plus 1 mg/kg lidocaine (ketamine-lidocaine group, n = 22) for induction of anaesthesia in addition to 0.05 mg/kg midazolam (in both groups). Our primary outcome was the mean arterial pressure (MAP). Other outcomes included frequency of post-induction hypotension, heart rate, and cardiac output.

RESULTS

Forty-three patients were available for final analysis. The average MAP reading in the first 5 min post-induction was higher in ketamine-lidocaine group than in the ketamine group {82.8 ± 5.6 mmHg and 73 ± 10.2 mmHg, P < 0.001}. Furthermore, the incidence of post-intubation hypotension was lower in the ketamine-lidocaine group than in the ketamine group {1 patient (5%) versus 17 patients (77%), P < 0.001}. The ketamine-lidocaine group showed higher MAP in almost all the readings after induction compared to ketamine group. Other haemodynamic variables including cardiac output and heart rate were comparable between both study groups.

CONCLUSION

Lidocaine-ketamine combination showed less incidence of hypotension compared to ketamine full-dose when used for rapid-sequence endotracheal intubation in patients with septic shock. REGISTRATION URL: https://clinicaltrials.gov/ct2/show/NCT03844984?cond=NCT03844984&rank=1.

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.

Accuracy and trending of non-invasive oscillometric blood pressure monitoring at the wrist in obese patients

BACKGROUND

In obese patients, non-invasive blood pressure monitoring in the arm is difficult due to the arm size and morphology. We compared the non-invasive oscillometric wrist blood pressure measurement with the arm and forearm in obese patients monitored with invasive radial blood pressure (reference standard).

METHODS

This prospective observational study included adult obese patients scheduled for bariatric surgery. Non-invasive blood pressure was measured at the arm, upper forearm and wrist of one upper extremity, while invasive blood pressure was simultaneously measured through a radial arterial catheter in the contralateral upper extremity. The accuracy of non-invasive blood pressure reading at each site was evaluated for absolute and trending values using the Bland-Altman analysis and Spearman's correlation coefficient.

RESULTS

In 40 patients, 262, 259, and 263 pairs of non-invasive blood pressure readings were obtained from the arm, forearm, and wrist sites, respectively. As primary outcome, the correlation coefficient for systolic blood pressure was higher for the wrist (0.92, 95% confidence interval (CI) [0.9-0.94]) than for the arm (0.74, 95% CI [0.68-0.79]) and the forearm (0.71, 95% CI [0.64-0.76]) (P<0.05). The non-invasive systolic wrist blood pressure showed the least mean bias and the narrowest limits of agreement (-0.3±7.6mmHg) when compared with forearm (4.3±16) and arm measurements (14.2±13.6) (P<0.05). For trending values, the correlation coefficient was the highest at the wrist.

CONCLUSION

In obese patients undergoing bariatric surgery, non-invasive blood pressure measured at the wrist showed the highest accuracy in comparison with the arm and forearm.

Pulse wave velocity and short-term outcome in patients requiring intravascular volume expansion: a pilot study

BACKGROUND

Fluid therapy has a pivotal role in the management of acutely ill patients. However, whether or not a patient can tolerate additional intravascular volume is controversial and optimal strategy is unknown. Carotid femoral pulse wave velocity (cfPWV) evaluates arterial stiffness.

OBJECTIVE

To determine whether cfPWV can predict the ability of patients to tolerate clinically indicated acute fluid expansion.

METHODS

50 consecutive patients requiring intravascular volume expansion were prospectively recruited in intensive care units. All subjects underwent transthoracic echocardiography, pulmonary ultrasound assessment, and a cfPWV study (S. Giovanni Bosco Hospital in Turin, Italy, between 2015 and 2016) at baseline and after 24 hours. Acute outcomes were registered at 24 hours ("soft" end points) and 30 days ('hard' end points: death, acute myocardial infarction, stroke, occurrence of atrial fibrillation, need for dialysis) after initial fluid therapy. Multivariate logistic regression was used to assess association of the initial cfPWV with outcomes.

RESULTS

cfPWV was significantly higher (10.6±3.6 vs 7.4±2.2 m/s, P<0.0001) in subjects who met the prespecified combined endpoints (hard or soft) than in those who did not. After adjustment for confounding factors, initial cfPWV was significantly and independently associated with the occurrence of hard events (OR=2.8 (95% CI 1.36 to 5.97), P=0.005; area under the receiver operating characteristic curve 84%). cfPWV of <9 m/s had a negative predictive value of 93%, excluding hard events associated with fluid expansion.

CONCLUSION

cfPWV appears to reflect the ability of the patient to tolerate an intravascular fluid expansion when clinically indicated. Increased cfPWV could help to identify subjects at greater risk of developing signs and symptoms of fluid overload.

The ability of perfusion index to detect segmental ulnar nerve sparing after supraclavicular nerve block

Supraclavicular nerve block (SCB) is a commonly used regional block for upper extremity surgery. The most common form of failure of SCB is ulnar segmental sparing. We aimed to evaluate the accuracy of perfusion index (PI) in early detection of segmental sparing of the ulnar component of SCB. A prospective observational study included adult patients scheduled for surgery under ultrasound-guided SCB. PI was simultaneously measured at the index finger and little finger. PI was recorded every minute for the first 10 min after SCB. PI ratio was calculated at every measurement point as PI/baseline PI. The area under the receiver operating characteristic (AUROC) curve was calculated for the ability of PI ratio to detect segmental ulnar sparing with comparison of little finger readings to the index finger readings. Forty-nine patients were available for the final analysis. Nine patients (18%) had segmental ulnar sparing. PI ratio at the little finger showed excellent predictive ability for ulnar sparing starting from the fifth minute (AUROC 0.92 [0.8-0.98], cutoff value ≤ 1.71) and reached the highest value at the seventh minute (AUROC 0.96 [0.86-1], cutoff value ≤ 1.35), whereas PI ratio at the index finger showed poor predictive ability. When using the PI for evaluation of successful SCB, segmental ulnar sparing could be accurately detected when the PI was measured at the little finger and not at the index finger. An increase of 71% in PI at the little finger 5 min after SCB could accurately rule out ulnar sparing.Clinical trial identifier NCT03880201. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT03880201?term=NCT03880201&draw=2&rank=1 .

Pulse Pressure Variation-Guided Fluid Therapy during Supratentorial Brain Tumour Excision: A Randomized Controlled Trial

BACKGROUND:

Goal-directed fluid therapy (GDFT) improved patient outcomes in various surgical procedures; however, its role during mass brain resection was not well investigated.

AIM:

In this study, we evaluated a simple protocol based on intermittent evaluation of pulse pressure variation for guiding fluid therapy during brain tumour resection.

METHODS:

Sixty-one adult patients scheduled for supratentorial brain mass excision were randomized into either GDFT group (received intraoperative fluids guided by pulse pressure variation) and control group (received standard care). Both groups were compared according to the following: brain relaxation scale (BRS), mean arterial pressure, heart rate, urine output, intraoperative fluid intake, postoperative serum lactate, and length of hospital stay.

RESULTS:

Demographic data, cardiovascular data (mean arterial pressure and heart rate), and BRS were comparable between both groups. GDFT group received more intraoperative fluids {3155 (452) mL vs 2790 (443) mL, P = 0.002}, had higher urine output {2019 (449) mL vs 1410 (382) mL, P < 0.001}, and had lower serum lactate {0.9 (1) mmol versus 2.5 (1.1) mmol, P = 0.03} compared to control group.

CONCLUSION:

In conclusion, PPV-guided fluid therapy during supratentorial mass excision, increased intraoperative fluids, and improved peripheral perfusion without increasing brain swelling.

The Impact of Goal-Directed Fluid Therapy in Prolonged Major Abdominal Surgery on Extravascular Lung Water and Oxygenation: A Randomized Controlled Trial

BACKGROUND:

A growing interest had been paid to goal-directed fluid therapy (GDT) in abdominal surgery; however, its impact on the respiratory profile was not well investigated.

AIM:

We evaluated the impact of GDT on postoperative extravascular lung water and oxygenation after prolonged major abdominal surgery.

METHODS:

A randomised, controlled study was conducted in Kasr Alainy hospital from April 2016 till December 2017 including 120 adult patients scheduled for prolonged major abdominal surgery. Patients were randomised into either GDT group (n = 60) who received baseline restricted fluid therapy (2 mL/Kg/hour) which is guided by stroke volume variation, or control group (n = 60) who received standard care. Both study groups were compared according to hemodynamic data, fluid requirements, lung ultrasound score, and PaO2/fraction of inspired oxygen ratio (P/F ratio),

RESULTS:

Intraoperatively, GDT group received less volume of fluids and showed higher intraoperative mean arterial pressure compared to the control group. Postoperatively, lung ultrasound score was lower, and P/F ratio was higher in the GDT group compared to the control group. The number of patients who showed a significant postoperative increase in LUS was higher in the control group 44 (73%) patients versus 14 (23%) patients, P < 0.001).

CONCLUSIONS:

Using stroke volume variation for guiding fluid therapy in prolonged, major abdominal operations were associated with better hemodynamic profile, less intraoperative fluid administration, lower extravascular lung water and better oxygenation compared to standard care.

Validity of mini-fluid challenge for predicting fluid responsiveness following liver transplantation

BACKGROUND

Mini-fluid challenge is a well tested and effective tool to predict fluid responsiveness under various clinical conditions. However, mini-fluid challenge has never been tested in patients with end-stage liver disease. This study investigated whether infusion of 150 ml albumin 5% can predict fluid responsiveness in cirrhotic patients following liver transplant.

METHODS

Fifty patients receiving living donor liver transplant were included in the analysis. Mini-fluid challenge composed of 150 ml of albumin 5% administered over 1 min in three consecutive 50-ml fluid boluses. An additional 350 ml was then infused at a constant rate over 15 min (for a total of 500 ml). Stroke volume (SV) was measured as the product of the subaortic velocity time integral (VTI) and left ventricular outflow tract (LVOT) area. Fluid responsiveness was defined as an increase in SV by ≥15% after the infusion.

RESULTS

Fifty patients were enrolled in the study. Fourteen patients were classified with Child A, 15 patients with Child B, and 21 patients with Child C cirrhosis. Thirty four patients were fluid responders and 16 patients were fluid non-responders. After 150 ml of albumin 5%, the SV increased significantly in our cohort. The area under receiver operating curve (AUROC) was 0.7 (95% confidence interval [CI] 0.5-0.8, P = 0.005). In subgroup analysis, the SV increased significantly after mini fluid challenge in the Child A group (P = 0.017) but not Child B or C groups (P = 0.3 and 0.29, respectively). The AUROC for mini-fluid challenge in the Child A group was 0.86 (95% confidence interval [CI] 0.6-0.9, P = 0.0004), while mini-fluid challenge failed to discriminate between responders and non-responders in Child B and C groups.

CONCLUSION

A mini-fluid challenge of 150 ml albumin 5% can predict fluid responsiveness in liver transplant patients with fair sensitivity and specifiicty. Subgroup analyis revealed that minifluid challenge can predict fluid responsiveness in patients with Child A cirrhosis but not patients with Child B or C cirrhosis.

TRIAL REGISTRATION

NCT03396159 . (Prospective registered). Initial registration date was 10/01/2018.

Fluid therapy in non-septic, refractory acute decompensated heart failure patients - The cautious role of central venous pressure

PURPOSE

Fluid therapy in congestive acute decompensated heart failure (ADHF) patients might be inappropriate and worsening the prognosis. The aim of our study was to analyze the effect of fluid administration on mortality in non-septic, ADHF patients with reduced ejection fraction.

MATERIAL AND METHODS

We analyzed 41 ADHF consecutive 'cold-wet' patients (mean age 69.3 ± 14.9 years, 27 men, LVEF 22.8 ± 11.1%, lactates 2.2 ± 1.6 mmol/L) without sepsis. At admission central venous pressure (CVP) was measured (17.6 ± 7.2 cm H₂O), and ultrasound examination of inferior vena cava (IVC) was performed (IVC min. 18.6 ± 7.3 mm and IVC max. 24.6 ± 4.3 mm). Moreover, the groups were compared (survivors vs. non-survivors as well as 1st and 4th quartile of CVP).

RESULTS

Altogether 17 (41%) patients died: 16 (39%) during a mean of 11.2 ± 7.8 days of hospitalization and 1 during a 30-day follow up. Patients in the lowest CVP quartile (<13 cm H₂O) had significantly worse in-hospital survival as compared to patients in the highest quartile (>24 cm H₂O), P = 0.012. Higher intravenous fluid volumes within the first 24 h were infused in patients in the lowest CVP quartile as compared to the highest CVP quartile (1791.7 ± 1357.8 mL vs. 754.5 ± 631.4 mL, P = 0.046). Moreover, more fluids were infused in a group of patients who died during a hospital stay and at 30-day follow up (1362.8 ± 752.7 mL vs. 722.7 ± 1046.5 mL, P = 0.004; 1348.8 ± 731.0 mL vs. 703.6 ± 1068.4 mL, P = 0.002, respectively).

CONCLUSIONS

CVP-guided intravenous fluid therapy is a common practice which in high risk ADHF 'cold-wet' patients might be harmful and should rather be avoided. Lower CVP seems to be related with worse prognosis.

Accuracy and trending of non-invasive hemoglobin measurement during different volume and perfusion statuses

The evolution of non-invasive hemoglobin measuring technology would save time and improve transfusion practice. The validity of pulse co-oximetry hemoglobin (SpHb) measurement in the perioperative setting was previously evaluated; however, the accuracy of SpHb in different volume statuses as well as in different perfusion states was not well investigated. The aim of this work is to evaluate the accuracy and trending of SpHb in comparison to laboratory hemoglobin (Lab-Hb) during acute bleeding and after resuscitation. Seventy patients scheduled for major orthopedic procedures with anticipated major blood loss were included. Radical-7 device was used for continuous assessment of SpHb, volume status [via pleth variability index (PVI)] and perfusion status [via perfusion index (PI)]. Lab-Hb and SpHb were measured at three time-points, a baseline reading, after major bleeding, and after resuscitation. Samples were divided into fluid-responsive and fluid non-responsive samples, and were also divided into high-PI and low-PI samples. Accuracy of SpHb was determined using Bland-Altman analysis. Trending of SpHb was evaluated using polar plot analysis. We obtained 210 time-matched readings. Fluid non-responsive samples were 106 (50.5%) whereas fluid responsive samples were 104 (49.5%). Excellent correlation was reported between Lab-Hb and SpHb (r = 0.938). Excellent accuracy with moderate levels of agreement was also reported between both measures among all samples, fluid non-responsive samples, fluid-responsive samples, high-PI samples, and low-PI samples [Mean bias (limits of agreement): 0.01 (- 1.33 and 1.34) g/dL, - 0.08 (- 1.27 and 1.11) g/dL, 0.09 (- 1.36 and 1.54) g/dL, 0.01 (- 1.34 to 1.31) g/dL, and 0.04 (- 1.31 to 1.39) g/dL respectively]. Polar plot analysis showed good trending ability for SpHb as a follow up monitor. In conclusion, SpHb showed excellent correlation with Lab-Hb in fluid responders, fluid non-responders, low-PI, and high PI states. Despite a favorable mean bias of 0.01 g/dL for SpHb, the relatively wide levels of agreement (- 1.3 to 1.3 g/dL) might limit its accuracy. SpHb showed good performance as a trend monitor.

Does stroke volume variation predict fluid responsiveness in children: A systematic review and meta-analysis

OBJECTIVE

Stroke volume variation (SVV) is a reliable predictor of fluid responsiveness in adult patients. However, the predictive value of SVV is uncertain in pediatric patients. We performed the first systematic meta-analysis to evaluate the diagnostic value of SVV in predicting fluid responsiveness in children.

METHODS

PUBMED, EMBASE, and Cochrane Central Register of Controlled Trials were searched up to December 2016. Original studies assessing the diagnostic accuracy of SVV in predicting fluid responsiveness in children were considered to be eligible. A random-effects model was used to calculate pooled values of sensitivity, specificity and diagnostic odds ratio with 95% CI. The summary receiver operating characteristic curve was estimated and area under the curve was calculated. Quality of the studies was assessed with the QUADAS-2 tool.

RESULTS

Six studies with a total of 279 fluid boluses in 224 children were included. The analysis demonstrated a pooled sensitivity of 0.68 (95% CI,0.59-0.76), pooled specificity of 0.65 (95% CI, 0.57-0.73), pooled diagnostic odds ratio of 8.24 (95% CI, 2.58-26.30), and the summary area under the summary receiver operating characteristic curve of 0.81. However, significant inter-study heterogeneity was found (p<0.05, I2 = 61.3%), likely due to small sample size and diverse study characteristics.

CONCLUSIONS

Current evidence suggests that SVV was of diagnostic value in predicting fluid responsiveness in children under mechanical ventilation. Given the high heterogeneity of published data, further studies are needed to confirm the diagnostic accuracy of SVV in predicting fluid responsiveness in pediatric patients.

A novel particle filtering method for estimation of pulse pressure variation during spontaneous breathing

Background

We describe the first automatic algorithm designed to estimate the pulse pressure variation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV) from arterial blood pressure (ABP) signals under spontaneous breathing conditions. While currently there are a few publicly available algorithms to automatically estimate \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV accurately and reliably in mechanically ventilated subjects, at the moment there is no automatic algorithm for estimating \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV on spontaneously breathing subjects. The algorithm utilizes our recently developed sequential Monte Carlo method (SMCM), which is called a maximum a-posteriori adaptive marginalized particle filter (MAM-PF). We report the performance assessment results of the proposed algorithm on real ABP signals from spontaneously breathing subjects.

Results

Our assessment results indicate good agreement between the automatically estimated \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV and the gold standard \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV obtained with manual annotations. All of the automatically estimated \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV index measurements (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}_{\text {auto}}$$\end{document}PPVauto) were in agreement with manual gold standard measurements (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}_{\text {manu}}$$\end{document}PPVmanu) within ±4 % accuracy.

Conclusion

The proposed automatic algorithm is able to give reliable estimations of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {PPV}$$\end{document}PPV given ABP signals alone during spontaneous breathing.