The effects of hypoproteinemia and volume expansion on lung and soft tissue transvascular fluid filtration

Resuscitation from major trauma or replacement of major operative blood loss frequently results in varying levels of protein depletion and alterations in plasma volume. To assess the importance of these factors on pulmonary and soft tissue transvascular fluid filtration, we compared the effects of hypoproteinemia and plasma volume expansion on the rate of lung and soft tissue transvascular fluid filtration in unanesthetized adult sheep. Ten animals were surgically prepared with chronic lung and soft tissue lymph fistulas. Lung (QL) and soft tissue (Qs) lymph flow rates were used to determine changes in transvascular fluid filtration. Initially, lactated Ringer's solution (LR) was infused to elevate pulmonary arterial wedge pressure of normoproteinemic animals (Norm/LR) 5 mm Hg for 2 1/2 hours. After a plasmapheresis-induced protein depletion of 30% to 35%, similar volume expansions with LR (Hypo/LR) and fresh frozen plasma (Hypo/Plas) were performed. Plasma, lung lymph, and soft tissue lymph oncotic pressures were determined, and transvascular oncotic gradients were calculated. Plasma volume expansion during Hypo/Plas conditions limited (p less than or equal to 0.05, 3 hours after infusion) Qs elevations compared with Hypo/LR expansion. However, there appeared to be no significant advantage with fresh frozen plasma over LR infusion in limiting QL. During fresh frozen plasma infusion, a distinct 10- to 12-hour lag in protein transport into the interstitium was observed in the soft tissue but not the lung microcirculation. The resultant differences in fluid filtration properties were in part the result of significant widening of the oncotic gradient in soft tissue. Plasma protein infusion appeared not to be beneficial over LR in limiting lung transvascular fluid filtration during hypoproteinemic states but significantly decreased soft tissue transvascular fluid flux.     

Hydroxyethyl starch pretreatment in bacteremic sheep.

Live bacteria were infused in a chronic ovine lung lymph model to determine if a preceding infusion of the colloid, hydroxyethyl starch (HES), exaggerated the cardiopulmonary dysfunction or impaired removal of bacteria by macrophages in the pulmonary circulation. HES was infused (3 mL/kg/hr; n = 6) from 24 to 12 hr before the bacteria and decreased plasma protein content and increased pulmonary lymph to plasma protein concentration because of its oncotic properties. Ringer's lactate (2 mL/kg/hr) was given after stopping HES and also to the control group (n = 6). Infusion of live Ps. aeruginosa (2.5 x 10(8) Ps./min for approximately 30 min) induced equivalent pulmonary hypertension, increased pulmonary microvascular permeability, and cardiovascular depression in the two groups. The removal of bacteria in the lungs was not affected, indicating that this measurement of the function of the mononuclear phagocytic system was not impaired by the preceding HES.     

急性扩容性血液稀释电解质的影响

目的对比观察乳酸钠林格液和万汶在术前急性扩容性血液稀释前后电解质的变化。方法20例病人随机分为万汶组(组1)和乳酸钠林格液组(组2)。病人入室开放静脉后分别给予两组液体15 ml/kg,30 min输注完毕。分别于输液前后抽血查血常规、电解质。结果两组扩容前后MAP、HR无明显变化,血K+稀释性降低。组1扩容后HCT下降明显,血Na+明显增加,但仍在正常范围之内。组2扩容后HCT明显下降,血Na+在正常范围之内。结论万汶扩容效果优于乳酸钠林格液,但可致血Na+升高,血K+稀释性降低。     

Effect of nonprotein colloid on postburn edema formation in soft tissues and lung

We studied the effect of a nonprotein colloid solution--namely low molecular weight dextran (LMWD)--on edema formation in burned and nonburned soft tissue and lung. Adult sheep with lung and bilateral flank lymph fistulas were given a unilateral 25% to 30% full-thickness burn under ketamine anesthesia and followed for 72 hours. Resuscitation (24-hour period) was performed with lactated Ringer solution (LR) (n = 9) or 10% LMWD in saline (n = 8) to restore baseline vascular pressures and cardiac output. Interstitial edema and microvascular protein permeability were monitored by lymph flow (QL) and lymph to plasma protein ratio, respectively. With LR, QL values in nonburned skin and lung were increased twofold to threefold in the first 24 hours, while with LMWD, values remained at baseline. The nonburn edema with LR was due to the burn-induced hypoproteinemia state. The prevention of this process with LMWD was due to the generation of a twofold to threefold increase in the plasma to interstitial colloid osmotic pressure (COP) gradient. Burn QL was increased fivefold in both groups despite a higher COP gradient with LMWD. Net fluid requirements for the first 24 hours were 75 and 35 ml/kg for animals treated with LR and LMWD, respectively. After cessation of dextran administration in the second 24 hours, the COP gradients for the two groups were equal but QL in nonburned skin and net fluid requirements now increased significantly in the LMWD group. The development of nonburn edema was believed to be due to the persistent hypoproteinemic state. We conclude that edema formation in nonburned tissues, which is due to hypoproteinemia, accounts for a substantial amount of the net fluid requirements after thermal injury. This process can be prevented by infusion of a nonprotein colloid as long as the COP gradient is increased. Edema in burned tissue appears to be unaffected by changes in COP.     

Early colloid replacement therapy in a near-fatal model of hemorrhagic shock

Several controlled, experimental, hypotensive models of hemorrhagic shock have evaluated the effects of timing, rate, and types of fluid replacement. In a near-fatal experimental model we evaluated the hemodynamic and metabolic effects of two types of solutions for fluid resuscitation. In this study, 30 young Large-White pigs were randomly assigned to three groups: Group I (control, n= 10), not bled; Group II (hydroxyethyl starch, HES, n = 10), submitted to controlled hemorrhage to a mean arterial blood pressure (MAP) of 30 mmHg and blood lactate >10 mM/L, at which time resuscitation was initiated with 7 mL/kg of HES 130/0.4 6% followed by 33 mL/kg of lactated Ringer's solution (LR) and retransfusion; Group III (LR, n = 10), submitted to controlled hemorrhage to a MAP of 30 mmHg and blood lactate >10 mM/L, at which time resuscitation was initiated with 40 mL/kg of LR followed by retransfusion. The resuscitation with HES 130/0.4 proved to be superior to LR, expressed by hemodynamic and perfusion variables. Despite improvement in tissue perfusion, MAP did not totally return to baseline values. In conclusion, early colloid infusion resulted in prompt recovery of tissue perfusion when compared with infusion with an equal volume of crystalloid.     

An in vitro study comparing the effects of Hextend, Hespan, normal saline, and lactated ringer's solution on thrombelastography and the activated partial thromboplastin time

OBJECTIVE: The purpose of this study was to determine if 6% HES 450/0.7 (hydroxyethyl starch 450/0.7) in normal saline (Hespan) and 6% HES 450/0.7 in lactated Ringer's solution (Hextend) have the same inhibition of the intrinsic coagulation pathway and platelet function. Multiple studies have suggested that 6% Hespan inhibits coagulation and increases chest tube drainage and transfusion requirements in cardiac surgical patients. There have been few studies of the effects of 6% Hextend, a relatively new plasma volume expander, on coagulation and the results thus far have been mixed. DESIGN: A prospective in vitro study. SETTING: A large academic medical center. PARTICIPANTS: Blood was collected from 30 healthy volunteers. Interventions : The blood was fractionated and diluted by 30% with Hextend, Hespan, normal saline, and lactated Ringer's solutions, with a native sample for a control. MEASUREMENTS AND MAIN RESULTS: Primary outcome measures were thromboelastography and activated partial thromboplastin time (APTT). For each of the TEG parameters, there was no difference between samples diluted with Hextend compared with Hespan (p > or = 0.112 in all cases). APTT did not differ significantly between samples diluted with Hextend compared with Hespan (p = 0.562). CONCLUSIONS: This prospective in vitro study suggests that Hextend and Hespan, hydroxyethyl starch 450/0.7 in different base solutions, exhibit the same effect on platelet function as measured by the TEG.     

Effects of Crystalloid and Colloid Preload on Blood Volume in the Parturient Undergoing Spinal Anesthesia for Elective Cesarean Section

Background: The role of crystalloid preloading to prevent hypotension associated with spinal anesthesia in parturients during cesarean section has been challenged. Direct measurement of blood volume should provide insight regarding the volume-expanding effects. The aim of the current study was to clarify the effects of volume preload with either crystalloid or colloid solution on the changes in blood volume of parturients undergoing spinal anesthesia for cesarean section.

Methods: Thirty-six healthy parturients scheduled for elective cesarean section during spinal anesthesia were allocated randomly to one of three groups receiving 1.5 l lactated Ringer's solution (LR; n = 12), 0.5 l hydroxyethylstarch solution, 6% (0.5 l HES; n = 12), and 1.0 l hydroxyethylstarch solution, 6% (1.0 l HES; n = 12), respectively. Blood volume and cardiac output were measured before and after volume preloading with indocyanine green (ICG), and the indocyanine green blood concentrations were monitored by noninvasive pulse spectrophotometry.

Results: After volume preload, the blood volume significantly increased in all three groups (P< 0.01). The volume of infused solution remaining in the vascular space in the LR, 0.5-l HES, and 1.0-l HES groups were 0.43 +/- 0.20 l, 0.54 +/- 0.14 l, and 1.03 +/- 0.21 l, respectively, corresponding to 28% of lactated Ringer's solution and 100% of hydroxyethylstarch solution infused. Significant increases in cardiac output were observed in the 0.5-l and 1.0-l HES groups (P< 0.01). A significant correlation between the percentage increase in blood volume and that of cardiac output was observed by volume preloading (r2 = 0.838;P< 0.001). The incidence of hypotension was 75% for the LR group, 58% for the 0.5-l HES group, and 17% for the 1.0-l HES group, respectively.     

The effect of plasma oncotic pressure on the pulmonary microcirculation after hemorrhagic shock.

Plasma oncotic pressure is considered to be an important factor in controlling lung water after hemorrhagic shock. However, it is the gradient between plasma and interstitial oncotic pressure which affects the pulmonary transvascular fluid filtration rate, Qf. Our objective was to determine the effect of decreasing plasma oncotic pressure, pip, on Qf, on interstitial oncotic pressure pii, and on the oncotic gradient. Chronic lung lymph fistulas were created in 16 sheep. Lymph flow, a reliable index of Qf, plasma and lymph (equal to interstitial) oncotic pressures, and vascular pressures were monitored in unanesthetized sheep, before and during hemorrhagic shock (50% blood volume), during resuscitation (3 hours), and during recovery (24 hours). Resuscitation was either with shed blood or lactated Ringer's solution in sufficient quantity to return left atrial pressure and cardiac output to baseline levels. During resuscitation with blood, lymph flow increased by 115%. The pip remained constant, while pii decreased, increasing the oncotic gradient. Crystalloid resuscitation produced on increase in lymph flow equal to that in the blood group at 120% over baseline; however, pip decreased by 50%, producing an oncotic gradient 4 mm Hg less than that of blood group. This was not reflected by a difference in Qf between the groups. During recovery Qf returned to baseline in the blood group and in most of the crystalloid group, as the oncotic gradient returned to baseline, despite a significant decrease in pip due to a compensatory decrease in pii. We conclude that during resuscitation Qf does not appear to be increased by a decrease in the oncotic gradient. During recovery a major decrease in pip can be compensated for rapidly by a decrease in pii, leading to no change in interstitial fluid content.     

The dynamics of vascular volume and fluid shifts of lactated Ringer's solution and hypertonic-saline-dextran solutions infused in normovolemic sheep

Infusions of hyperosmotic-hyperoncotic solutions such as hypertonic saline dextran (HSD) are used in Europe for resuscitation of traumatic shock and perioperative volume support as an adjunct to conventional isotonic crystalloids. Whereas plasma volume expansion of HSD has been measured at single time points after the intravascular volume expansion, the detailed time course of fluid shifts during and after infusions have not been reported. We compared the time course of volume expansion during and after 30-min infusions of 4 mL/kg HSD and 25 mL/kg lactated Ringer's solution (LR) in normovolemic conscious splenectomized sheep. Peak plasma volume (Evans blue and hemoglobin dilution) expansion was similar for HSD (7.8 +/- 0.9 mL/kg) and the larger sixfold volume of LR (7.2 +/- 0.5 mL/kg). However, 30 min after the 30-min infusion (T60), plasma expansion remained larger after HSD (5.1 +/- 0.9 mL/kg) than after LR (1.7 +/- 0.6 mL/kg). Both solutions caused an equivalent diuresis. Intravascular volume expansion efficiency (VEE), defined as milliliter plasma expansion/milliliter fluid infused at 0 (T30), 30 (T60), and 60 (T90) min after infusion ended was 1.8, 1.3, and 0.8, respectively for HSD, whereas LR provided a VEE of only 0.27, 0.07, and 0.07. The relative expansion efficiency of HSD versus LR, calculated as the ratio (VEE(HSD)/VEE(LR)), was 7-fold that of LR at the end of infusion T30, and 20-fold at T60, but decreased to 9-fold by T120. Intravascular volume dynamic studies of different volume expanders in animals and patients may provide anesthesiologists with a new tool for monitoring the effectiveness of fluid therapy. IMPLICATIONS: Hypertonic saline dextran (HSD) is a new plasma expander recently approved for clinical use in Europe. We compared the plasma volume expansion of HSD versus lactated Ringers (LR) in normovolemic sheep. After a 30 min infusion, HSD was 7 times as effective at expanding volume as an equal volume of LR, but for the next 90 minutes the relative effectiveness of HSD increased to 10-20 times.     

Oxygen-lactated Ringer's solution for surgical patients]

The effects of intravenous infusion of the lactated Ringer's solution inflated with oxygen (Oxygen-LR) and lactated Ringer's solution (LR) on oxygenation of blood were studied in 23 patients undergoing abdominal surgery under epidural anesthesia. LR 1000 ml was infused with inflated oxygen at 1L/min in 30 minutes in the oxygen-LR group (n = 12). The partial pressure of oxygen-LR was increased to 600.45 +/- 78.78 from 129.4 +/- 9.69 mmHg. LR 1000 ml was infused in 30 minutes in the control group (n = 11). There was no significant difference in PaO2, PaCO2, SatO2, A-aDO2 during and 30 minutes after infusion between the oxygen-LR and control groups. We believe that oxygen-LR is of no clinical value because of its low ability is of no carrying oxygen.     

Lung lymph response to overinfusion with hydroxyethyl starch in sheep. Comparative studies of high and low molecular weight compounds

BACKGROUND: Several hydroxyethyl starch (HES) solutions are available clinically. We performed comparative studies of low and high molecular weight HES to evaluate the effects on lung lymph flow in sheep, to see the difference in the types of HES. METHODS: We prepared awake sheep with vascular monitorings and lung lymph fistulas. We measured systemic artery pressure (Psa), pulmonary artery pressure (Ppa), and left atrial pressure (Pla) continuously. Cardiac output (CO) was measured every 30 min. Lung lymph flow (Qlym) was collected every 15 min. After baseline measurements, two HES solutions were infused over 2 h, respectively. Experiment 1 (n=6): low molecular weight HES (MW 70 000, substitution ratio 0.5-0.55), Experiment 2 (n=5): high molecular weight HES (MW 450 000, substitution ratio 0.7). RESULTS: Both low and high molecular HES behaved similarly as a volume expander, increasing Psa, CO, Pla and Ppa, and decreasing hematocrit. In addition, the actual oncotic pressure gradient (plasma - lymph) was widened after the start of either low or high molecular HES, but the value for high molecular HES was significantly higher than that for low molecular HES. Qlym of low molecular HES rose significantly from the baseline and the percent increase in Qlym for low molecular HES was significantly higher than that for high molecular HES. CONCLUSION: These data suggest that low molecular HES is as useful a plasma substitute as high molecular HES, but may increase lung fluid filtration in the overinfused state.     

The effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia

We evaluated the effects of an infusion of lactated Ringer's (LR) solution on changes in cardiac output (CO) after spinal anesthesia. Seventy-five patients scheduled for lower extremity surgery under spinal anesthesia were studied. We measured CO (impedance cardiography method) and blood pressure for 25 min before and 30 min after spinal anesthesia. Patients were randomly assigned to three groups. In the No Infusion group, no LR solution was given during the period of measurements. The LR Before group received 12 mL/kg of LR solution within 20 min before spinal anesthesia. The LR After group received 12 mL/kg of LR solution within 20 min starting immediately after spinal anesthesia. After spinal anesthesia, CO decreased by 13.9% in the No Infusion group. In the LR Before group, CO increased after the infusion by 20% and returned to baseline value 30 min after spinal anesthesia. In the LR After group, CO increased after spinal anesthesia, and 30 min after spinal anesthesia, CO was 11.3% above baseline. We conclude that the decrease in CO after spinal anesthesia can be prevented by the infusion of an LR solution, with CO reaching the highest value while the infusion is running. IMPLICATIONS: We studied the effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia. If the patients received no infusion, cardiac output decreased after spinal anesthesia. However, if the patients received lactated Ringer's solution infusion, cardiac output was maintained.     

Sampling of lung interstitial fluid in intact dog

This paper reports a method of sampling fluid from the peribronchial-perivascular space (PBVS) of the lungs in intact closed chest dogs. The PBVS was sampled by introducing a wick catheter into the PBVS through a mediastinoscope. The right lymph duct was cannulated by the method of Vriem and Ohkuda [J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 54: 199, 1983] for collection of lymph to compare to peribronchial fluid. The colloid osmotic pressure (COP) of PVBS and right lymph duct fluid (RLDF) were compared in a series of dogs infused with lactated Ringer's solution (LR) and lactated Ringer's combined with three other conditions: left atrial balloon inflation (LRB), oleic acid infusion (LRO), and oleic acid infusion and left atrial balloon inflation (LROB). Prior to LR infusion, the volume of samples of fluid from the PBVS wicks was inadequate for measuring COP (less than 4 microliters). This difference was significantly only in the later samples at 3, 4, and 5 hr in the LR and LRB groups. In the LRO and LROB groups, protein content and amount of fluid sampled were greater than in the LR and LRB groups, but the mean COPs of the wick PBVS and RLDF were not significantly different. This method of directly sampling interstitial fluid from the lungs of dogs without thoracotomy confirms the high COP of fluid from the lung interstitium. This method of PBVS fluid sampling is potentially feasible in a human patient undergoing mediastinoscopy.     

Early hemodynamic and renal effects of hemorrhagic shock resuscitation with lactated Ringer's solution, hydroxyethyl starch, and hypertonic saline with or without 6% dextran-70

BACKGROUND: Considering the renal effects of fluid resuscitation in hemorrhaged patients, the choice of fluid has been a source of controversy. In a model of hemorrhagic shock, we studied the early hemodynamic and renal effects of fluid resuscitation with lactated Ringer's (LR), 6% hydroxyethyl starch (HES), and 7.5% hypertonic saline (HS) with or without 6% dextran-70 (HSD). MATERIALS AND METHODS: Forty-eight dogs were anesthetized and submitted to splenectomy. An estimated 40% blood volume was removed to maintain mean arterial pressure (MAP) at 40 mm Hg for 30 min. The dogs were divided into four groups: LR, in a 3:1 ratio to removed blood volume; HS, 6 mL kg(-1); HSD, 6 mL kg(-1); and HES in a 1:1 ratio to removed blood volume. Hemodynamics and renal function were studied during shock and 5, 60, and 120 min after fluid replacement. RESULTS: Shock treatment increased MAP similarly in all groups. At 5 min, cardiac filling pressures and cardiac performance indexes were higher for LR and HES but, after 120 min, there were no differences among groups. Renal blood flow and glomerular filtration rate (GFR) were higher in LR at 60 min but GFR returned to baseline values in all groups at 120 min. Diuresis was higher for LR at 5 min and for LR and HES at 60 min. There were no differences among groups in renal variables 120 min after treatment. CONCLUSIONS: Despite the immediate differences in hemodynamic responses, the low-volume resuscitation fluids, HS and HSD, are equally effective to LR and HES in restoring renal performance 120 min after hemorrhagic shock treatment.     

Pulmonary and systemic fluid filtration after continuous versus bolus interleukin-2 infusion

Interleukin-2 has been widely investigated as adjuvant therapy for advanced cancer and is administered by either bolus or continuous infusion. We compared the effects of bolus and continuous interleukin-2 infusion on pulmonary (QL) and systemic microvascular fluid filtration in 11 adult sheep prepared with chronic lung and soft-tissue lymph fistulas. Interleukin-2 was administered as a bolus infusion (100,000 units/kg) every 8 hours for 3 days or as a continuous infusion at the same dose for 3 days. No significant changes in pulmonary hydrostatic pressures or pulmonary vascular resistance were noted after either bolus or continuous interleukin-2 infusion. However, significantly decreased (p less than or equal to 0.05) systemic vascular resistances were observed in both groups. QL increased steadily throughout the infusion period in both groups, peaking at three times baseline on the third infusion day. The plasma/interstitial protein clearance (QL X lymph/plasma protein ratio) rose similarly in both groups, indicating increased barrier permeability. Increased lymphocyte clearance into lung lymph occurred by day 3 but was not associated with lymphocytic sequestration in the lung interstitium. We conclude that pulmonary and systemic microvascular fluid and protein flux exhibit similar changes after bolus or continuous interleukin-2 infusion. These changes are associated with increased clearance of lymphocytes into lung lymph that are not sequestered in the pulmonary interstitium after infusions of shorter duration.     

PHYSICOCHEMICAL CHANGES DURING HAEMORRHAGE AND FOLLOWING INFUSION

Interstitial fluid pressure (IFP) and plasma colloid osmoticpressure (plasma COP) were measured in dogs following acutehaemorrhage and following the infusion of saline, 10% dextran40 in saline and 3% dextran 40 in lactated Ringer's solution.Exsanguination decreased IFP, plasma COP and total plasma proteinand albumin concentrations, and increased plasma glucose concentrationand osmotic pressure. A massive infusion of physiological salineincreased IFP, and decreased plasma COP and total plasma proteinand albumin concentrations. The volume of saline infused correlatedwith the increase in IFP. When a 10% dextran 40 saline solutionwas used, there was a marked increase in plasma COP but a decreasein IFP. When 3% dextran 40 in lactated Ringer's solution wasinfused, IFP was little affected in the early stage, but graduallyincreased thereafter. Plasma COP increased slightly immediatelyafter infusion, but remained near the pre-exsanguination valuefor at least 3 h.     

The early systemic and gastrointestinal oxygenation effects of hemorrhagic shock resuscitation with hypertonic saline and hypertonic saline 6% dextran-70: a comparative study in dogs

The smaller volemic state from hypertonic (7.5%) saline (HS) solution administration in hemorrhagic shock can determine lesser systemic oxygen delivery and tissue oxygenation than conventional plasma expanders. In a model of hemorrhagic shock in dogs, we studied the systemic and gastrointestinal oxygenation effects of HS and hyperoncotic (6%) dextran-70 in combination with HS (HSD) solutions in comparison with lactated Ringer's (LR) and (6%) hydroxyethyl starch (HES) solutions. Forty-eight mongrel dogs were anesthetized, mechanically ventilated, and subjected to splenectomy. A gastric air tonometer was placed in the stomach for intramucosal gastric CO(2) (Pgco(2)) determination and for the calculation of intramucosal pH (pHi): The dogs were hemorrhaged (42% of blood volume) to hold mean arterial blood pressure at 40-50 mm Hg over 30 min and were then resuscitated with LR (n = 12) in a 3:1 relation to removed blood volume; HS (n = 12), 6 mL/kg; HSD (n = 12), 6 mL/kg; and HES (mean molecular weight, 200 kDa; degree of substitution, 0.5) (n = 12) in a 1:1 relation to the removed blood volume. Hemodynamic, systemic, and gastric oxygenation variables were measured at baseline, after 30 min of hemorrhage, and 5, 60, and 120 min after intravascular fluid resuscitation. After fluid resuscitation, HS showed significantly lower arterial pH and mixed venous Po(2) and higher systemic oxygen uptake index and systemic oxygenation extraction than LR and HES (P < 0.05), whereas HSD showed significantly lower arterial pH than LR and HES (P < 0.05). Only HS and HSD did not return arterial pH and pHi to control levels (P < 0.05). In conclusion, all solutions improved systemic and gastrointestinal oxygenation after hemorrhagic shock in dogs. However, the HS solution showed the worst response in comparison to LR and HES solutions in relation to systemic oxygenation, whereas HSD showed intermediate values. HS and HSD solutions did not return regional oxygenation to control values.     

A comparison of lactated ringer's solution to hydroxyethyl starch 6% in a model of severe hemorrhagic shock and continuous bleeding in dogs

In this randomized, controlled study in dogs, we examined the short-term effects of blood pressure targeted fluid resuscitation with colloids or crystalloids solutions on systemic oxygen delivery, and lactate blood concentration. Fluid resuscitation using hydroxyethyl starch (HES) 6% to a mean arterial blood pressure (MAP) of 60 mm Hg was compared with lactated Ringer's solution (LR) to a MAP of 60 or 80 mm Hg (LR60 and LR80, respectively). The model was one of withdrawal of blood to a MAP of 40 mm Hg through an arterial catheter that was then connected to a system allowing bleeding to occur throughout the study whenever MAP exceeded 40 mm Hg. Target MAP was maintained for 60 min with a continuous infusion of the designated fluid replacement. All 15 dogs (5 in each group) survived until the last measurement. Blood loss in the LR80 group (2980 +/- 503 mL) (all values mean +/- SD) was larger than in the LR60 and HES60 groups (1800 +/- 389 mL, and 1820 +/- 219 mL, respectively) (P < 0.001). Whereas 840 +/- 219 mL of HES60 was needed to maintain target MAP, 1880 +/- 425 mL of LR was needed in the LR60 group, and 4590 +/- 930 mL in the LR80 group (P < 0.001). Lactate blood concentrations were smaller and delivered O(2) higher in the HES60 group (35 +/- 17 mg/dL and 239 +/- 61 mL/min, respectively) in comparison to the LR60 group (89 +/- 18 mg/dL and 140 +/- 48 mL/min, respectively) and the LR80 group (75 +/- 23 mg/dL and 153 +/- 17 mL/min, respectively) (P = 0.02 and P = 0.026). In conclusion, fluid resuscitation during uncontrolled bleeding, to a target MAP of 60 mm Hg, using HES60 resulted in larger oxygen delivery and smaller systemic lactate A resuscitation to a target MAP of 60 or 80 mm Hg using LR. IMPLICATIONS: Fluid resuscitation to a target mean arterial blood pressure of 60 mm Hg during uncontrolled bleeding resulted in larger oxygen delivery and smaller systemic lactate concentrations when hydroxyethyl starch 6% was used, in comparison to lactated Ringer's solution resuscitation to a target mean arterial blood pressure of 60 or 80 mm Hg.     

Hemodynamic and pulmonary effects of fluid resuscitation from hemorrhagic shock in the presense of mild pulmonary edema

The hemodynamic and pulmonary effects of fluid resuscitation with crystalloid and colloid solutions in the presence of mild pulmonary edema were investigated. Anesthetized dogs received oleic acid to increase pulmonary capillary permeability, and one hour later bled to produce hemorrhagic shock. One hour after the shock, resuscitation was performed with Ringer's lactate, 6% hydroxyethyl starch (HES) solution, or dog's plasma. Resuscitation from hemorrhagic shock restored hemodynamics to pre-hemorrhagic levels with all of the above solutions. Ringer's lactate resuscitation resulted in increases in extravascular lung water volume (EVLWV) and oxygen consumption, and decreases in colloid osmotic pressure and oxygen delivery. Resuscitation with HES solution and plasma did not result in increases in EVLWV, but with HES solution resulted in decreases in colloid osmotic pressure to pre-hemorrhagic levels in two hours. This suggests that the resuscitation with HES solution can not maintain colloid osmotic pressure for more than two hours. The author concludes that the hemodynamic and pulmonary effects of HES solution and plasma are similar in mild lung injury cases.     

Influence of fluid infusion associated with high-volume blood loss on plasma propofol concentrations

BACKGROUND: It is common clinical practice to use fluid infusion to manage high-volume blood loss until a blood transfusion is performed. The authors investigated the influence of fluid infusion associated with blood loss on the pseudo-steady state propofol concentration. METHODS: Twenty-seven swine were assigned to a lactated Ringer's solution group, a hydroxyethyl starch group, or a threefold lactated Ringer's solution group (n = 9 in each group). After 180 min of steady state infusion of propofol at a rate of 2 mg.kg(-1).h(-1), hemorrhage and infusion were induced by stepwise bleeding followed by fluid infusion every 30 min. In each of the first two steps, 400 ml blood was collected; thereafter, 200 ml was collected at each step. Just after each bleeding step, fluid infusion was rapidly performed using a volume of lactated Ringer's solution or hydroxyethyl starch equivalent to the blood withdrawn, or a threefold volume of lactated Ringer's solution. Hemodynamic parameters and the plasma propofol concentration were recorded at each step. RESULTS: Although the plasma propofol concentration in the lactated Ringer's solution group increased with hemorrhage and infusion, it decreased in both the hydroxyethyl starch and the threefold lactated Ringer's solution groups. The propofol concentration in the hydroxyethyl starch group could be expressed by the following equation: Plasma Propofol Concentration Decrease (%) = 0.80 x Hematocrit Decrease (%) (r2 = 0.83, P < 0.0001). CONCLUSIONS: When high-volume blood loss is managed by isovolemic hemodilution, the plasma propofol concentration during continuous propofol infusion decreases linearly with the hematocrit decrease.