Fluid balance

Crystalloid administration among patients undergoing liver surgery: Defining patient- and provider-level variation

BACKGROUND

Fluid administration among patients undergoing liver resection is a key aspect of perioperative care. We sought to examine practice patterns of crystalloid administration, as well as potential factors associated with receipt of crystalloid fluids.

METHOD

Patients who underwent liver resection between 2010 and 2014 were identified. Data on clinicopathologic variables, operative details, and perioperative fluid administration were collected and analyzed using univariable and multivariable analyses; variation in practice of crystalloid administration was presented as coefficient of variation (COV).

RESULTS

Among 487 patients, median crystalloid administered at the time of surgery was 4,000 mL. After adjusting for body size and operative duration, median corrected crystalloid was 30.0 mL kg(-1) m(2) h(-1), corresponding with a COV of 35%. Patients who received <30 mL kg(-1) m(2) h(-1) crystalloids were more likely to be younger (58 vs 60 years), white (79% vs 74%), and have a higher body mass index (BMI; 28.2 vs 25.4 kg/m(2); all P < .001). On multivariable analysis, increasing Charlson comorbidity index, BMI, estimated blood loss, and each additional hour of surgery were all associated with increased crystalloid administration (all P < .05). Corrected crystalloid administration varied among providers with a corrected COV ranging from 14% to 61%. When overall variation in crystalloid administration was assessed, 80% of the variation occurred at the patient level, and 20% occurred at the provider level (surgeon, 3% vs anesthesiologist, 17%).

CONCLUSION

There was wide variability in crystalloid administration among patients undergoing liver resection. Although the majority of variation was attributable to patient factors, a large amount of residual variation was attributable to provider-level differences.

Goal-directed fluid therapy based on stroke volume variations improves fluid management and gastrointestinal perfusion in patients undergoing major orthopedic surgery

OBJECTIVE

To evaluate the influence of stroke volume variation (SVV)-based goal-directed therapy (GDT) on splanchnic organ functions and postoperative complications in orthopedic patients.

SUBJECTS AND METHODS

Eighty patients scheduled for major orthopedic surgery under general anesthesia were randomly allocated to one of two equal groups to receive either intraoperative volume therapy guided by SVV (GDT) or standard fluid management (control). In the SVV group, patients received colloid boluses of 4 ml/kg to maintain an SVV <10% when in the supine position or an SVV <14% if prone. In the control group, fluids were given to maintain a mean arterial pressure >65 mm Hg, a heart rate <100 bpm, a central venous pressure of 8-14 mm Hg, and a urine output >0.5 ml/kg/h. Intraoperative organ perfusion, hemodynamic data, hospitalization, postoperative complications, and mortality were recorded.

RESULTS

The heart rate at the end of surgery was significantly lower (p < 0.05), there were fewer hypotensive episodes (p < 0.05), the arterial and gastric intramucosal pH were higher (p < 0.05 for both), the gastric intramucosal PCO2 was lower (p < 0.05), the intraoperative infused colloids and the total infused volume were lower (p < 0.05 for both), and the postoperative time to flatus was shorter (p < 0.05) in the GDT group than in the control group. No differences in the length of hospital stay, complications, or mortality were found between the groups.

CONCLUSION

SVV-based GDT during major orthopedic surgery reduced the volume of the required intraoperative infused fluids, maintained intraoperative hemodynamic stability, and improved the perioperative gastrointestinal function.

Intraoperative fluid management in open gastrointestinal surgery: goal-directed versus restrictive

OBJECTIVE

The optimal strategy for fluid management during gastrointestinal surgery remains unclear. Minimizing the variation in arterial pulse pressure, which is induced by mechanical ventilation, is a potential strategy to improve postoperative outcomes. We tested this hypothesis in a prospective, randomized study with lactated Ringer's solution and 6% hydroxyethyl starch solution.

METHOD

A total of 60 patients who were undergoing gastrointestinal surgery were randomized into a restrictive lactated Ringer's group (n = 20), a goal-directed lactated Ringer's group (n = 20) and a goal-directed hydroxyethyl starch group (n = 20). The goal-directed fluid treatment was guided by pulse pressure variation, which was recorded during surgery using a simple manual method with a Datex Ohmeda S/5 Monitor and minimized to 11% or less by volume loading with either lactated Ringer's solution or 6% hydroxyethyl starch solution (130/0.4). The postoperative flatus time, the length of hospital stay and the incidence of complications were recorded as endpoints.

RESULTS

The goal-directed lactated Ringer's group received the greatest amount of total operative fluid compared with the two other groups. The flatus time and the length of hospital stay in the goal-directed hydroxyethyl starch group were shorter than those in the goal-directed lactated Ringer's group and the restrictive lactated Ringer's group. No significant differences were found in the postoperative complications among the three groups.

CONCLUSION

Monitoring and minimizing pulse pressure variation by 6% hydroxyethyl starch solution (130/0.4) loading during gastrointestinal surgery improves postoperative outcomes and decreases the discharge time of patients who are graded American Society of Anesthesiologists physical status I/II.

Colloid vs. crystalloid infusions in gastrointestinal surgery and their different impact on the healing of intestinal anastomoses

BACKGROUND

The aim of this study was to investigate if colloid infusions have different effects on intestinal anastomotic healing when compared to crystalloid infusions depending on the amount of the administered volume.

MATERIALS AND METHODS

Twenty-eight Wistar rats were randomly assigned to four groups receiving different amounts of either a crystalloid (Cry) or a colloid (Col) infusion solution. Animals with volume restriction (Cry (-) or Col (-)) were treated with a low and animals with volume overcharge (Cry (+) or Col (+)) with a high flow rate. All animals received an infusion for a 60-min period, while an end-to-end small bowel anastomosis was performed. At reoperation, the anastomotic bursting pressure (millimeters of mercury) was measured, as well as anastomotic hydroxyproline concentration. The presence of bowel wall edema was assessed histologically.

RESULTS

Median bursting pressures were comparable in the Col (-) [118 mm Hg (range 113-170)], the Cry (-) [118 mm Hg (78-139)], and the Col (+) [97 mm Hg (65-152)] group. A significantly lower median bursting pressure was found in animals with crystalloid volume overload Cry (+) [73 mm Hg (60-101)]. Corresponding results were found for hydroxyproline concentration. Histology revealed submucosal edema in Cry (+) animals.

CONCLUSIONS

In case of a fixed, high-volume load, colloids seem to have benefits on intestinal anastomotic healing when compared to crystalloid infusions.

[Haemodynamic monitoring in the perioperative phase. Available systems, practical application and clinical data]

A regular hydration status and compensated vascular filling are targets of perioperative fluid and volume management and, in parallel, represent precautions for sufficient stroke volume and cardiac output to maintain tissue oxygenation. The physiological and pathophysiological effects of fluid and volume replacement mainly depend on the pharmacological properties of the solutions used, the magnitude of the applied volume as well as the timing of volume replacement during surgery. In the perioperative setting surgical stress induces physiological and hormonal adaptations of the body, which in conjunction with an increased permeability of the vascular endothelial layer influence fluid and volume management. The target of haemodynamic monitoring in the operation room is to collect data on haemodynamics and global oxygen transport, which enable the anaesthetist to estimate the volume status of the vascular system. Particularly in high risk patients this may improve fluid and volume therapy with respect to maintaining cardiac output. A goal-directed volume management aiming at preventing hypovolaemia may improve the outcome after surgery. The objective of this article is to review the monitoring devices that are currently used to assess haemodynamics and filling status in the perioperative setting. Methods and principles for measuring haemodynamic variables, the measured and calculated parameters as well as clinical benefits and shortcomings of each device are described. Furthermore, the results for monitoring devices from clinical studies of goal-directed fluid and volume therapy which have been published will be discussed.

Perioperative hemodynamic monitoring with transesophageal Doppler technology

Invasive cardiac output (CO) monitoring, traditionally performed with transpulmonary thermodilution techniques, is usually reserved for high-risk patients because of the inherent risks of these methods. In contrast, transesophageal Doppler (TED) technology offers a safe, quick, and less invasive method for routine measurements of CO. After esophageal insertion and focusing of the probe, the Doppler beam interrogates the descending aortic blood flow. On the basis of the measured frequency shift between the emitted and received ultrasound frequency, blood flow velocity is determined. From this velocity, combined with the simultaneously measured systolic ejection time, CO and other advanced hemodynamic variables can be calculated, including estimations of preload, afterload, and contractility. Numerous studies have validated TED-derived CO against reference methods. Although the agreement of CO values between TED and the reference methods is limited (95% limits of agreement: median 4.2 L/min, interquartile range 3.3-5.0 L/min), TED has been shown to accurately follow changes of CO over time, making it a useful device for trend monitoring. TED can be used to guide perioperative intravascular volume substitution and therapy, with vasoactive or inotropic drugs. Various studies have demonstrated a reduced postoperative morbidity and shorter length of hospital stay in patients managed with TED compared with conventional clinical management, suggesting that it may be a valuable supplement to standard perioperative monitoring. We review not only the technical basis of this method and its clinical application but also its limitations, risks, and contraindications.

How I manage donors and patients with a weak D phenotype

PURPOSE OF REVIEW

Since the adoption of molecular blood-group typing, the considerable heterogeneity of the serologic entities weak D and DEL at the molecular level has come to light. I offer an approach to the management of donors and patients expressing D antigen weakly and carrying any of the various molecular types of weak D and DEL.

RECENT FINDINGS

More than 50 distinct weak D alleles have been described. An internet-based survey of anti-D immunizations occurring in D-positive transfusion recipients reveals that no allo-anti-D has been observed in patients carrying prevalent weak D types. Allo-immunizations are documented for weak D types 4.2 (also known as DAR), 11 and 15. Anti-D immunizations have been reported in D-negative persons transfused with weak D and DEL red blood cells.

SUMMARY

Patients carrying any of the prevalent weak D types 1, 2, 3 or 4.1 are not prone to allo-anti-D immunization and may safely be transfused with D-positive red blood cells. Pregnant women with these weak D types need not receive RhIg. We should pay attention to weak D- or DEL-positive blood units that are labelled D-negative. The clinical benefit of removing DEL blood units from our supply of D-negative red blood cell units should be determined.

A clue to the basis of allelic enhancement: occurrence of the Ax subgroup in the offspring of blood group O parents

Apparent deviation from Mendelian rules of blood group inheritance is rarely observed. Blood group O parents with children expressing weak A subgroups have occasionally been described but not explained. A detailed serological investigation of such a family is described here. The ABO locus was analysed by PCR-ASP/restriction fragment length polymorphism genotyping and DNA sequencing. The propositus' RBCs were very weakly agglutinated with monoclonal anti-A but distinctly with polyclonal anti-A,B, i.e. typical for Ax. Serum anti-A1 (titre 4) and -B were present. Her parents' blood groups were both clearly O, with titres of serum anti-A1, and -A at 16 and 4, respectively. Adsorption/ elution studies demonstrated A antigen on the daughter's cells only. The ABO genotypes were: mother, AxO1; father, O1vO2; and propositus, AxO2. The Ax allele was an A1-O1v hybrid allele with a crossing-over breakpoint between positions 235 and 446 in intron 6 (Ax-4). Compared to the A1 glycosyltransferase, this allele predicts a protein with two amino acid substitutions (Phe216Ile and Met277Val) known to yield either weakly expressed or no A antigen on RBCs. This study suggests that the nature of the ABO allele in trans can influence A antigen expression, a phenomenon previously described as allelic enhancement (or reinforcement). Potential mechanisms for this are discussed.