Distribution of crystalloid fluid infused during onset of anesthesia-induced hypotension: a retrospective population kinetic analysis

Background Induction of anesthesia causes a drop in arterial pressure that might change the kinetics of infused crystalloid fluid. The aim of this report is to provide a mathematical view of how fluid distributes in this setting. Methods Data were retrieved from three studies where 76 patients (mean age 63 years, mean body weight 66 kg) had received approximately 1.1 L of Ringer’s solution over 60 min by intravenous infusion before and during induction of spinal, epidural, or general anesthesia. A population kinetic model was used to analyze the fluid distribution and its relationship to individual-specific factors. Frequent measurements of blood hemoglobin and the urinary excretion served as dependent variables. Results Before anesthesia induction, distribution to the extravascular space was threefold faster than elimination by urinary excretion. Both distribution and elimination of infused fluid were retarded in an exponential fashion due to the anesthesia-induced decrease in the mean arterial pressure (MAP). A decrease in MAP from 110 to 60 mmHg reduced the rate of distribution by 75% and the rate of elimination by 90%. These adaptations cause most of the infused fluid to remain in the bloodstream. Age, gender, type of anesthesia, and the use of ephedrine had no statistically significant effect on plasma volume expansion, apart from their possible influence on MAP. Conclusion The decrease in MAP that accompanies anesthesia induction depresses the blood hemoglobin concentration by inhibiting both the distribution and elimination of infused crystalloid fluid. The report provides mathematical information about the degree of these changes.

Interstitial washdown and vascular albumin refill during fluid infusion: novel kinetic analysis from three clinical trials

Background and aims Increased capillary filtration may paradoxically accelerate vascular refill of both fluid and albumin from the interstitial space, which is claimed to be edema-preventing. We characterized this proposed mechanism, called “interstitial washdown”, by kinetic analyses of the hemodilution induced by intravenous infusion of crystalloid fluid during 3 distinct physiological states. Methods Greater plasma dilution of hemoglobin as compared to albumin during fluid therapy indicated recruitment of albumin, which was compared to the flow of interstitial fluid to the plasma as indicated by population volume kinetic analysis. Data for the comparison were derived from 24 infusions of crystalloid fluid in conscious volunteers, 30 in anesthetized patients, and 31 in patients with ketoacidosis from hyperglycemia. Results “Interstitial washdown” increased the plasma albumin concentration by between 0.3 and 1.0 g/L in the three series of infusions. The initial albumin concentration in the interstitial fluid returning to the plasma was estimated to between 22 g/L and 29 g/L, which decreased to an average of 50–75% lower during the subsequent 2–3 h. Kinetic simulations show that pronounced washdown was associated with increased capillary filtration (high k12) and, in conscious subjects, with greater plasma and interstitial volume expansion and restricted urine flow. During anesthesia, the main effect was an increase in the non-exchangeable fluid volume (“third-spacing”). Conclusions Crystalloid fluid accelerates lymphatic flow that moderately increases plasma albumin, but more clearly helps to maintain the intravascular volume. This “interstitial washdown” mechanism becomes exhausted after a few hours.

Effect of Woolen Cloth to Maintain Temperature 39°C of Crystaloid Fluid Ringer Lactate at Room Temperature 18°C

Fluid resuscitation with 39ᵒC is one of the main therapies for hypovolemic (hemorrhagic) shock patients to prevent complications. In this time, we already have tools to keep the fluid warm, but not all health services have these tools. To find out the effectiveness of using woolen cloth against the temperature of Ringer Lactate 39°C crystalloid fluid at room temperature 18°C. This study used a pre-experimental method, with a static group comparison approach, with 4 Ringer Lactate liquid samples divided into 2 groups, namely groups using wool cloth and those not using woolen cloth. Data collected through observation sheets. Data analyzed using the Mann Whitney test. With this p value (0.00001) <α (0.05), it can be concluded that there is a significant difference between the use of woolen cloth and those that do not use woolen cloth. The woolen cloth is effective to slow down the decrease in temperature of the crystalloid liquid Ringer Lactate 39ᵒC at room temperature 18ᵒC. The difference in temperature changes in the Ringer Lactate crystalloid fluid is influenced by several things including humidity, ambient temperature, and additional material used.

Distribution of Crystalloid Fluid Infused During Onset of Anesthesia-Induced Hypotension: A Retrospective Population Kinetic Analysis

Background. Loading with crystalloid fluid before induction of anesthesia is widely practiced but cannot reduce the accompanying drop in arterial pressure. The aim of this report is to provide a mathematical view of how fluid distributes in this setting.Methods. Data were retrieved from three studies where 76 patients (mean age 63 years, mean body weight 66 kg) had received approximately 1.1 L of Ringer’s solution over 60 min by intravenous infusion before and during induction of spinal, epidural, or general anesthesia. A population kinetic model was used to analyze the fluid distribution and its relationship to individual-specific factors. Frequent measurements of blood hemoglobin and the urinary excretion served as dependent variables.Results. Before anesthesia induction, distribution to the extravascular space was 3-fold faster than elimination by urinary excretion. Both distribution and elimination of infused fluid were retarded in an exponential fashion due to the anesthesia-induced decrease in the mean arterial pressure (MAP). A decrease in MAP from 110 to 60 mmHg reduced the rate of distribution by 75% and the rate of elimination by 90%. These adaptations cause most of the infused fluid to remain in the bloodstream. Age, gender, type of anesthesia, and the use of ephedrine had no statistically significant effect on plasma volume expansion, apart from their possible influence on MAP.Conclusion. The decrease in MAP that accompanies anesthesia induction depresses the blood hemoglobin concentration by inhibiting both the distribution and elimination of infused crystalloid fluid. The report provides mathematical information about the degree of these changes.

The hemodynamic effects of warm versus room-temperature crystalloid fluid bolus therapy in post-cardiac surgery patients

Introduction: The contribution of fluid temperature to the effect of crystalloid fluid bolus therapy (FBT) in post-cardiac surgery patients is unknown. We evaluated the hemodynamic effects of FBT with fluid warmed to 40°C (warm FBT) versus room-temperature fluid. Methods: In this single centre prospective before-and-after study, we evaluated the effects of 500 ml of warm versus room-temperature compound sodium lactate administered over <30 minutes, in 50 cardiac surgery patients admitted to ICU. We recorded hemodynamics continuous before and for 30 minutes after the first FBT. We defined CI responsiveness (CI-R) as an CI increase >15% of baseline immediately after FBT and effect dissipation if the CI returned to <5% of baseline and MAP responsiveness as >10% increase and dissipation as return to <3 mmHg of baseline. Results: Hypotension (56%) and low CI (40%) typically triggered FBT. Temperature decreased >0.3°C in 13 (52%) patients after room-temperature FBT versus 0 (0%) after warm FBT (p < 0.01). CI and MAP responsiveness was similar (16 [64%] versus 11 [44%], p = 0.15 and 15 [60%] versus 17 [68%], p = 0.77, respectively). Among CI responders, CI increased more with room-temperature FBT (+0.6 [IQR, 0.5–1.1] versus +0.5 [IQR, 0.4–0.6] L/min/m2, p = 0.01). However, dissipation was more common after room-temperature versus warm FBT (9/16 [56%] versus 1/11 [9%], p = 0.02). Conclusion: In postoperative cardiac surgery patients, warm FBT preserved core temperature and induced smaller but more sustained CI increases among responders. Fluid temperature appears to impact both core temperature and the duration of CI response.

T1 Initial Results of the American Burn Association (ABA) Multi-Center Evaluation on the Effectiveness of the Burn Navigator

Introduction The Burn Navigator (BN) is an FDA-cleared clinical decision support tool used to aid fluid resuscitation after major burn injury. The BN provides users with hourly recommendations for fluid titration during the initial resuscitation based on various factors. The objective of this multi-center observational study was to evaluate the resuscitation volumes and related outcomes of patients admitted to five ABA verified burn centers who underwent intravenous fluid resuscitation utilizing the BN. Methods Data was collected from 300 patients who were resuscitated utilizing the BN. Two analyses were performed: examination of the first 24 hours of resuscitation after burn injury and examination of 24 hours of resuscitation using the BN, regardless of when the resuscitation began, to account for patients who presented in a delayed fashion. Patients were classified as having followed the BN device if all hourly fluid rates were within 40 mL of the BN recommendations (20 mL above or below) for that hour at least 75% of the time. Results For 285 patients, average age, weight, and TBSA were 45.6 ± 16.8 years, 87.0 ± 22.8 kg, and 39.0 ± 17.8%, with partial/full thickness percentages of 22.2 ± 15.2% and 17.0 ± 19.7%, respectively. Analysis of 286 patients in the first 24 hours of resuscitation revealed an average of 4.07 ± 1.76 mL/kg/TBSA and 151.48 ± 77.46 mL/kg of primary crystalloid fluid. When considering all fluids administered to include colloids and medications, enteral and oral feeds, and oral resuscitation fluids, average volumes in the first 24 hours were 4.68 ± 2.06 mL/kg/TBSA and 175.01 ± 92.22 mL/kg. To account for delayed presentation after burn injury, examining 24 hours of resuscitation regardless of the initiation of resuscitation, average volumes for primary and total fluids were 5.28 ± 2.54 mL/kg/TBSA, 201.11 ± 106.53 mL/kg, 6.35 ± 2.95 mL/kg/TBSA and 244.08 ± 133.5 mL/kg respectively. There was a significant decrease incidence of shock in the BN-guided group versus the non-BN-guided group (p&lt; 0.05). Conclusions The Burn Navigator provides comparable resuscitation volumes of primary crystalloid fluid to the Parkland Formula. When all fluids are considered, the BN device recommends total fluid infusion less than the Ivy Index (250 mL/kg/24 hrs) and was associated with a decreased incidence of shock. Early initiation of the BN device resulted in lower overall fluid volumes during the first 24 hours of resuscitation.

Implications of Continuous Noninvasive Finger Cuff Arterial Pressure Device Use during Cesarean Delivery for Goal-Directed Fluid Therapy Preload Optimization: A Randomized Controlled Trial

Background. Although fixed-volume conventional fluid preloading protocol fails to attenuate postspinal hypotension during cesarean delivery, the effect of goal-directed fluid therapy (GDFT) remains less explored. Continuous noninvasive finger cuff arterial pressure monitoring using devices such as the ClearSight System can provide the noninvasive stroke volume value, enabling clinicians to perform GDFT before spinal anesthesia; however, the efficacy of GDFT requires further elucidation. Method. In total, 71 consecutive full-term pregnant women were randomly divided into a control group ( n = 34 ) and a GDFT group ( n = 37 ). Before spinal anesthesia, the control group received a fixed dose (1000 mL) of crystalloid fluid, but the GDFT group received repeated 3 mL/kg body weight of crystalloid fluid challenges within 3 minutes with a 1-minute interval between each fluid challenge based on the stroke volume incremental changes obtained using the ClearSight System (targeting a stroke volume increase of ≥5% after a fluid challenge). The primary outcome was the incidence of postspinal hypotension. The secondary outcomes were total fluid volume, vasopressor dosage, hemodynamic parameter changes, maternal adverse effects, and neonatal profiles. Result. Women in the GDFT group received more fluid than did those in the control group ( 1132 ± 108 vs. 1247 ± 202 mL; p = 0.0044 ), but the incidence of postspinal hypotension (79.4% vs. 73.0%,; p = 0.5864 ) and norepinephrine dose ( 12.5 ± 10.6 vs. 15.1 ± 12.8 mcg, respectively; p = 0.3512 ) was comparable between the two groups. Fewer women in the GDFT group experienced nausea (61.76% vs. 35.14%; p = 0.0332 ). Neonatal outcomes (Apgar score and umbilical blood analysis) were comparable and typical in both groups. Conclusion. ClearSight-guided GDFT did not ameliorate postspinal hypotension but may reduce nausea. This trial is registered with NCT03013140.

Increased crystalloid fluid requirements during zone 3 Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) versus Abdominal Aortic and Junctional Tourniquet (AAJT) after class II hemorrhage in swine

Purpose Pelvic and lower junctional hemorrhage result in a significant amount of trauma related deaths in military and rural civilian environments. The Abdominal Aortic and Junctional Tourniquet (AAJT) and infra-renal (zone 3) Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) are two options for resuscitation of patients with life threatening blood loss from and distal to the pelvis. Evidence suggest differences in the hemodynamic response between AAJT and zone 3 REBOA, but fluid management during resuscitation with the devices has not been fully elucidated. We compared crystalloid fluid requirements (Ringer’s acetate) between these devices to maintain a carotid mean arterial pressure (MAP) > 60 mmHg. Methods 60 kg anesthetized and mechanically ventilated male pigs were subjected to a mean 1030 (range 900–1246) mL (25% of estimated total blood volume, class II) haemorrhage. AAJT (n = 6) or zone 3 REBOA (n = 6) were then applied for 240 min. Crystalloid fluids were administered to maintain carotid MAP. The animals were monitored for 30 min after reperfusion. Results Cumulative resuscitative fluid requirements increased 7.2 times (mean difference 2079 mL; 95% CI 627–3530 mL) in zone 3 REBOA (mean 2412; range 800–4871 mL) compared to AAJT (mean 333; range 0–1000 mL) to maintain target carotid MAP. Release of the AAJT required vasopressor support with norepinephrine infusion for a mean 9.6 min (0.1 µg/kg/min), while REBOA release required no vasopressor support. Conclusion Zone 3 REBOA required 7.2 times more crystalloids to maintain the targeted MAP. The AAJT may therefore be considered in a situation of hemorrhagic shock to limit the need for crystalloid infusions, although removal of the AAJT caused more severe hemodynamic and metabolic effects which required vasopressor support.

Microvascular Fluid Exchange: Implications of the Revised Starling Model for Resuscitation of Dengue Shock Syndrome

Dengue is the most common mosquito-borne viral infection in the world. The most feared complication is a poorly understood vasculopathy that occurs in only a small minority of symptomatic individuals, especially children and young adults, but can result in potentially fatal dengue shock syndrome (DSS). Based mainly on expert opinion, WHO management guidelines for DSS recommend prompt infusion of a crystalloid fluid bolus followed by a tapering crystalloid fluid regimen, supplemented if necessary by boluses of synthetic colloid solutions. However, following publication of a number of major trials undertaken in other, primarily adult, critical care scenarios, use of both synthetic colloid solutions and of fluid boluses for volume expansion have become controversial. Synthetic colloids tend to be used for severe DSS cases in order to boost intravascular oncotic pressure, based on the classic Starling hypothesis in which opposing hydrostatic and oncotic forces determine fluid flow across the microvascular barrier. However, the revised Starling model emphasizes the critical contribution of the endothelial glycocalyx layer (EGL), indicating that it is the effective oncotic pressure gradient across the EGL not endothelial cells per se that opposes filtration. Based on several novel concepts that are integral to the revised Starling model, we review the clinical features of DSS and discuss a number of implications that are relevant for fluid management. We also highlight the need for context-specific clinical trials that address crucially important questions around the management of DSS.