Hemodynamic Responses to Crystalloid and Colloid Fluid Boluses during Noncardiac Surgery

Background Colloids are thought to sustain blood pressure and cardiac index better than crystalloids. However, the relative effects of intraoperative hydroxyethyl starch and crystalloid administration on the cardiac index and blood pressure remain unclear. This study therefore tested in this subanalysis of a previously published large randomized trial the hypothesis that intraoperative goal-directed colloid administration increases the cardiac index more than goal-directed crystalloid administration. Further, the effects of crystalloid and colloid boluses on blood pressure were evaluated. Methods This planned subanalysis of a previous trial analyzed data from 973 patients, of whom 480 were randomized to colloids and 493 were randomized to crystalloids. Fluid administration was guided by esophageal Doppler. The primary outcome was the time-weighted average cardiac index during surgery between the colloid and crystalloid group. The secondary outcomes were the cardiac index just after bolus administration, time elapsed between boluses, and the average real variability during surgery. The study recorded cardiac index, corrected flow time, and blood pressure at 10-min intervals, as well as before and after each bolus. Results Time-weighted average of cardiac index over the duration of anesthesia was only slightly greater in patients given colloid than crystalloid, with the difference being just 0.20 l · min–1 · m–2 (95% CI, 0.11 to 0.29; P < 0.001). However, the hazard for needing additional boluses was lower after colloid administration (hazard ratio [95% CI], 0.60 [0.55 to 0.66]; P < 0.001) in a frailty time-to-event model accounting for within-subject correlation. The median [quartiles] number of boluses per patient was 4 [2, 6] for colloids and 6 [3, 8] for crystalloids, with a median difference (95% CI) of –1.5 (–2 to –1; P < 0.001). The average real mean arterial pressure variability did not differ significantly between the groups (difference in means [95% CI] of –0.03 (–0.07 to 0.02) mmHg, P = 0.229). Conclusions There were not clinically meaningful differences in the cardiac index or mean pressure variability in patients given goal-directed colloid and crystalloids. As might be expected from longer intravascular dwell time, the interval between boluses was longer with colloids. However, on a case basis, the number of boluses differed only slightly. Colloids do not appear to provide substantial hemodynamic benefit. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Third-Generation Hydroxyethyl Starch Causes Dose-Dependent Coagulopathy in Patients Undergoing Off-Pump Coronary Artery Bypass with Continuation of Preoperative Aspirin

Background: We aimed to evaluate the effect of third-generation hydroxyethyl starch (6% HES 130/0.4) on hemostasis and perioperative blood loss in patients undergoing off-pump coronary artery bypass (OPCAB) with continuation of preoperative aspirin. Methods: Forty-nine consecutive patients, who underwent OPCAB at a single institution between November 1, 2014 and March 31, 2016, were included. Coagulation tests, including thromboelastometry and clinical data of all patients, retrospectively were collected from anesthesia and medical records. Results: The total amount of intraoperative crystalloid and HES was 2057.5 ± 771.6 mL (N = 32) and 1090.6 ± 645.0 mL (N = 32), respectively. In the coagulation pathway, the change ratio of fibrinogen concentration, prothrombin time, and fibrinogen thromboelastometry-maximum clot firmness (FIBTEM-MCF) significantly correlated with HES (P < 0.001, P = 0.00131, and P < 0.001, respectively), but not with crystalloid. In the coagulation pathway concerning interaction with platelets, the change ratio of platelet count, extrinsic thromboelastometry-clotting formation time (EXTEM-CFT), and EXTEM-MCF significantly were correlated with HES (P < 0.001, P < 0.001, and P < 0.001, respectively), but not with crystalloid. At chest closure, the hematocrit decreased in a dose-dependent manner with HES (P < 0.001), but not with crystalloid administration. There was an association between the change ratio of hematocrit and EXTEM-MCF (P = 0.00122). However, intra-postoperative blood loss was not correlated with HES 130/0.4 or crystalloid administration. Conclusion: We found that 6% HES 130/0.4 prolonged coagulation testing in a dose-dependent manner due to hemodilution but did not increase blood loss in patients undergoing OPCAB with continuation of preoperative aspirin.

Volume Resuscitation in the Acutely Hemorrhaging Patient: Historic Use to Current Applications

Acute hemorrhage in small animals results from traumatic and non-traumatic causes. This review seeks to describe current understanding of the resuscitation of the acutely hemorrhaging small animal (dog and cat) veterinary patient through evaluation of pre-clinical canine models of hemorrhage and resuscitation, clinical research in dogs and cats, and selected extrapolation from human medicine. The physiologic dose and response to whole blood loss in the canine patient is repeatable both in anesthetized and awake animals and is primarily characterized clinically by increased heart rate, decreased systolic blood pressure, and increased shock index and biochemically by increased lactate and lower base excess. Previously, initial resuscitation in these patients included immediate volume support with crystalloid and/or colloid, regardless of total volume, with a target to replace lost vascular volume and bring blood pressure back to normal. Newer research now supports prioritizing hemorrhage control in conjunction with judicious crystalloid administration followed by early consideration for administration of platelets, plasma and red blood during the resuscitation phase. This approach minimizes blood loss, ameliorates coagulopathy, restores oxygen delivery and correct changes in the glycocalyx. There are many hurdles in the application of this approach in clinical veterinary medicine including the speed with which the bleeding source is controlled and the rapid availability of blood component therapy. Recommendations regarding the clinical approach to volume resuscitation in the acutely hemorrhaging veterinary patient are made based on the canine pre-clinical, veterinary clinical and human literature reviewed.

Effects of individualized high positive end-expiratory pressure and crystalloid administration on postoperative pulmonary function in patients undergoing robotic-assisted radical prostatectomy: a prospective randomized single-blinded pilot study

Background Robotic-assisted laparoscopic prostatectomy (RALP) using a combination of capnoperitoneum and steep Trendelenburg positioning (STP) results in important pathophysiological pulmonary changes. The aim of the study was to evaluate if restrictive crystalloid administration and individual management of positive end-expiratory pressure (PEEP) improve peri- and postoperative pulmonary function in patients undergoing RALP in permanent 45 degree STP.Methods 98 patients undergoing RALP under standardized anesthesia were either allocated to a standard PEEP (5 mmHg) group or an individualized high PEEP group. Furthermore, each group was divided into a liberal vs restrictive crystalloid group (30 ml vs 15 ml per kg predicted body weight). Individualized PEEP levels were determined by means of preoperative PEEP titration in STP. In each of the four study groups following intraoperative parameters were analyzed: ventilation setting (PIP, driving pressure [Pdriv], lung compliance [LC], mechanical power [MP]), and postoperative pulmonary function (bed-side spirometry). The following spirometric parameters were measured pre- and postoperatively: the Tiffeneau index (FEV1/FVC ratio) and mean forced expiratory flow (FEF25 − 75). Data are shown as mean ± standard deviation (SD), and groups were compared with ANOVA. A P-value of < 0.05 was considered significant.Results The two individualized high PEEP groups (mean PEEP 15.5 [± 1.71 cmH2O]) showed significantly higher PIP and MP levels but significantly decreased Pdriv and increased LC. On the first and second postoperative day, patients with individualized higher PEEP levels had a significantly higher mean Tiffeneau index (day 1: 77.6% (± 6.6) vs 73.6% (± 8.8), P = 0.014; day 2: 76.5% (± 6.1) vs 72.7% (± 9.3), P = 0.021) and FEF25 − 75 (day 1: 2.41 liter/sec (± 0.9) vs 1.95 liter/sec (± 0.8), P = 0.009; day 2: 2.45 liter/sec (± 0.9) vs 2.07 liter/sec (± 0.8), P = 0.033). Perioperative oxygenation and postoperative spirometric parameters were not influenced by restrictive or liberal crystalloid infusion in either of the two PEEP groups.Conclusions Higher individualized PEEP levels during RALP improved blood oxygenation, lung-protective ventilation, and postoperative pulmonary function up to 48 hours after surgery. Restrictive crystalloid infusion during RALP seemed to have no effect on peri- and postoperative oxygenation and pulmonary function.

Analysis of intraoperative modifiable factors to prevent acute kidney injury after elective noncardiac surgery: intraoperative hypotension and crystalloid administration related to acute kidney injury

Background The optimal intraoperative blood pressure range and crystalloid administration protocol for the prevention of acute kidney injury (AKI) after elective noncardiac surgery remain unknown. Methods This single-center retrospective cohort study included 6296 patients aged ≥ 50 years who had undergone elective noncardiac surgery under general anesthesia. We evaluated the relationship between duration of intraoperative hypotension and AKI. To assess whether the effects of crystalloid administration differed according to baseline estimated glomerular filtration rate (eGFR), we examined the interaction between intraoperative crystalloid administration and eGFR. We calculated univariable and multivariable adjusted odds ratios (ORs) and their 95% confidence intervals (95% CIs) for the prevalence of AKI. Results AKI occurred in 431 (6.8%) patients and was associated with intraoperative hypotension. Effects of intraoperative crystalloid administration differed significantly according to baseline eGFR. Increased risk of AKI was noted in patients with eGFR ≤45 ml min−1 1.73m−2 who were managed with restrictive or liberal crystalloid administration [OR 4.79 (95% CI 3.10 to 7.32) and 6.43 (95% CI 2.23 to 16.03), respectively] as opposed to those with eGFR >45 ml min−1 1.73m−2 who were managed with moderately restrictive crystalloid administration. Conclusions Our findings suggest that anesthesiologists should avoid intraoperative hypotension as well as either restrictive or liberal (as opposed to moderately restrictive) crystalloid administration in patients with decreased eGFR. Intraoperative blood pressure and crystalloid administration protocol are major modifiable factors that must be optimized to prevent postoperative AKI.

Effect of intraoperative goal-directed balanced crystalloid versus colloid administration on postoperative maximum NT-proBNP concentration in patients undergoing noncardiac surgery

Background: N-terminal pro brain natriuretic peptide (NT-proBNP) and troponin T are released during myocardial wall stress and/or ischemia and are strong predictors for postoperative cardiovascular complications. However, the effect of goal-directed crystalloid versus colloid administration on NT-proBNP and troponin T, especially in relatively healthy patients undergoing moderate- to high risk abdominal surgery, still remains unclear. Thus, we evaluated in this sub-study the effect of a goal-directed crystalloid versus a goal-directed colloid fluid regimen on postoperative maximum NT-proBNP concentration. We further evaluated the incidence of MINS between both study groups. Methods: 30 patients were randomly assigned to receive additional intravenous fluid boluses of 6% hydroxyethyl starch 130/0.4 and 30 patients to receive lactated Ringer´s solution. Intraoperative fluid management was guided by oesophageal Doppler-according to a previously published algorithm. The primary outcome were differences in postoperative maximum NT-proBNP (maxNT-proBNP) between both groups. As our secondary outcome we evaluated the incidence of MINS between both study groups. We defined maxNT-proBNP as the maximum value measured within 2 hours after surgery and on the first and second postoperative day. Results: In total 56 patients were analysed. There was no significant difference in postoperative maximum NT-proBNP between the colloid group (258.7 ng/L (IQR 199.4 to 782.1)) and the crystalloid group (440.3 ng/L (IQR 177.9 to 691.2)) during the first 2 postoperative days (P = 0.29). 5 patients in the colloid group and 7 patients in the crystalloid group developed MINS (P = 0.75).Conclusions: Based on this relatively small study goal-directed colloid administration did not decrease postoperative maxNT-proBNP concentration as compared to goal-directed crystalloid administration. Trial registration: ClinicalTrials.gov (NCT01195883)

Intravenous Fluid Management Practices in Kidney Transplant Patients: A Multicenter Observational Cohort Pilot Study

Background Limited evidence exists with regard to best practices in fluid management during kidney transplantation, which may directly affect the incidence of DGF. The authors of this study embarked on a collaborative observational multicenter pilot study to evaluate fluid administration practices in different transplant centers, with a focus on the relationship between total administered crystalloid volume and its association with DGF. Methods Twenty consecutive kidney transplant patients were included from 9 academic medical centers in the United States. One hundred eighty patients were included in the final cohort and variables were compared between patients with and without DGF. Administered crystalloid volume was the primary variable of interest; however, additional patient and surgical variables were compared between patients with and without DGF. Variation in crystalloid administration was explored between centers by comparing median administered crystalloid volumes per kilogram of body weight. Also, unadjusted and adjusted logistic regression analyses were performed to determine which variables were independently associated with DGF. Results Multivariable regression modeling demonstrated that cold ischemic time and ephedrine use during surgery were independently associated with DGF. There was no independent association between administered crystalloid volume and DGF. Conclusion In this study of patients having kidney transplantation, we did not find an independent association between administered crystalloid volume and DGF, although there was significant variability in crystalloid administration between centers. Our data suggest that DGF was driven mainly by surgical factors such as cold ischemic time. Ephedrine was also independently associated with DGF, which should be explored in future studies.