Fluid therapy in shock

Three principal factors must be considered in initial fluid therapy in the treatment of shock: (a) blood volume deficit; (b) oxygen transport capacity; and (c) metabolic requirement of water and electrolytes. For the calculation of the initial volume to be used in compensatory blood volume loss, patients may be categorized thusly: group A—impending or slight loss [assumed loss of 20% of total blood volume (TBV)]; group B—moderate shock (20–35% of TBV); and group C—severe shock (>35% of TBV). These groups are treated initially with 20%, 30%, and 50% of TBV replacement, respectively. Treatment is individualized by continuous observation and changes are made as required. The relative merits and indications for use of crystalloid and colloid solutions are outlined. Oxygen delivery to the tissues must be guaranteed. The flow properties of the blood improve and the oxygen carrying capacity decreases with reducing hematocrit levels; a hematocrit reading of about 30 or slightly above is adequate. In determining the metabolic requirements, 3 factors must be considered: the physiologic daily requirement of water and electrolytes; the increased extrarenal fluid losses; and the reduction of the extracellular volume in trauma.     

Fluid therapy in burns

Abstract: The dissertation evaluates changes in transcapillary fluid and protein balance in the initial phase after extensive burns, comparing the effects of different regimens for post-burn fluid resuscitation. Studies were performed in anaesthetized rats and sheep. Within 15 min after major thermal injury, cardiac output (CO) was reduced by 40–50%, mainly due to a reduced stroke volume. Mean arterial pressure (MAP) also dropped by 30–40 mmHg. Both lactated Ringer's and plasma improved this postburn circulatory impairment. Rapid bolus infusions of small volumes of very hypertonic saline, 7.5% NaCl (2 400 mosmol/1), have rapidly corrected the circulatory impairment in haemorrhagic shock. Following a rapid bolus infusion of 7.5% NaCl in 6% Dextran 70, CO and MAP were completely restored, but the effect only lasted 30–60 min. When administered by a slow infusion, 7.5% NaCl gave no circulatory improvement. The transcapillary colloid-osmotic gradient was maintained in injured skin following infusion of plasma, whereas it was almost annihilated by infusion of lactated Ringer's. Plasma infusion thus induced a protein-rich edema in injured skin, whereas lactated Ringer's resulted in a generalized edema. Increased interstitial fluid flux can mobilize the interstitial matrix protcoglycan hyaluronan. Following burn injury, plasma concentrations of hyaluronan increased up to ten times above baseline. This observation suggests that at least some of the degradation of structural connective tissue components in thermally injured skin is by lymphatic removal (and subsequent degradation in liver). Increased plasma concentrations of interstitial components have not previously been observed after thermal injury.     

Fluid therapy for the surgical patient

Perioperative fluid therapy is the subject of much controversy, and the results of the clinical trials investigating the effect of fluid therapy on outcome of surgery seem contradictory. The aim of this chapter is to review the evidence behind current standard fluid therapy, and to critically analyse the trials examining the effect of fluid therapy on outcome of surgery. The following conclusions are reached: current standard fluid therapy is not at all evidence-based; the evaporative loss from the abdominal cavity is highly overestimated; the non-anatomical third space loss is based on flawed methodology and most probably does not exist; the fluid volume accumulated in traumatized tissue is very small; and volume preloading of neuroaxial blockade is not effective and may cause postoperative fluid overload. The trials of 'goal-directed fluid therapy' aiming at maximal stroke volume and the trials of 'restricted intravenous fluid therapy' are also critically evaluated. The difference in results may be caused by a lax attitude towards 'standard fluid therapy' in the trials of goal-directed fluid therapy, resulting in the testing of various 'standard fluid regimens' versus 'even more fluid'. Without evidence of the existence of a non-anatomical third space loss and ineffectiveness of preloading of neuroaxial blockade, 'restricted intravenous fluid therapy' is not 'restricted', but rather avoids fluid overload by replacing only the fluid actually lost during surgery. The trials of different fluid volumes administered during outpatient surgery confirm that replacement of fluid lost improves outcome. Based on current evidence, the principles of 'restricted intravenous fluid therapy' are recommended: fluid lost should be replaced and fluid overload should be avoided.     

重症患者的液体治疗

液体治疗是重症患者治疗的一个重要组成部分,其根本目的在于补充丢失的液体量,保证有效循环血容量,逆转组织器官低灌注及继发的器官功能障碍 [1-2].虽然液体治疗已在临床运用了近百年,但迄今为止仍没有一个理想的方案,在液体使用种类、时机及量的选择上仍存在诸多争议 [3].具体方案的选择是否合理对患者的预后有着重要的影响.现对近年发表的相关研究进行综述,希望能为临床液体治疗的开展提供有益的帮助.     

Fluid therapy in sepsis with capillary leakage

Sepsis is associated with a profound intravascular fluid deficit due to vasodilatation, venous pooling and capillary leakage. Fluid therapy is aimed at restoration of intravascular volume status, haemodynamic stability and organ perfusion. Circulatory stability following fluid resuscitation is usually achieved in the septic patient at the expense of tissue oedema formation that may significantly influence vital organ function. The type of fluid therapy, crystalloid or colloid, in sepsis with capillary leakage remains an area of intensive and controversial discussion. The current understanding of the physiology of increased microvascular permeability in health and sepsis is incomplete. Furthermore, there is a lack of appropriate clinical study end-points for fluid resuscitation. This review considers critically the clinical and experimental data analysing the assessment of capillary leakage in sepsis and investigating the effects of different fluid types on increased microvascular permeability in sepsis.     

Fluid therapy: Too much or too little

There is much debate regarding the amount of perioperative fluid administration in relation to patient outcome.Fluid shifting towards the interstitial space is of two types (physiologic and pathologic) across the vascular endothelial membrane. This membrane, of 1 μm thickness, is formed of an endothelial layer coated by glycocalyx, a small concentration of albumin, and a non-circulating part of plasma. It acts as a gateway to the interstitial space with a primary molecular filler function, generating an effective molecular filter function, generating an effective molecular gradient across its thickness.Since the early sixties, perioperative fluid requirements were calculated by considering pre-existing deficits, maintenance volumes, and third-spaces loss, depending on the type of surgery. Based on this, a goal-directed “liberal” fluid approach was modulated. On the other hand, a “restrictive” fluid approach was later suggested to achieve better patient outcome. Extremes of either approach were shown to induce hyper- or hypovolemia, respectively. However, there are no clear definitions to describe the volume status of patients.The literature is currently characterized by inconsistency and contradiction regarding patient outcome parallel to perioperative “too much” or “too little” fluid administration. There is no single fluid regimen which provides optimal fluid volumes to all surgical patients all the times. So, available literature is discussed in this article with an early evidence of a preferred “adequate” rather than a “liberal” or a “restrictive” fluid approach.Further systematic reviews of randomized controlled trials are recommended to predict the volumes and types of administered fluids, and its timing as important determinants of postoperative patient outcome. Special evidence is also needed for “liberal” versus “restrictive” hemoglobin therapy to determine the same goals.     

Fluid therapy for superior mesenteric artery occlusion shock in rats

The efficacy of three kinds of fluid such as isotonic sodium chloride (0.9% NaCl), hypertonic sodium chloride (7.5% NaCl) and iso-oncotic (3% in saline) albumin solutions to maintain the hemodynamics was investigated in rats with superior mesenteric artery occlusion (SMAO) shock. Three kinds of fluid were infused so as to maintain the mean arterial pressure within 70% of the control values. Animals in the control group without fluid therapy died within three hours because of shock. Three regimens could maintain the mean arterial blood pressure over three hours. The hypertonic crystalloid solution was effective in the early period of SMAO shock to regain the blood pressure by infusing a small volume. An excessively large amount of volume was required in the group infused with an isotonic crystalloid, providing inadequate tissue perfusion. The iso-oncotic colloid produced a stable circulatory status with minimum changes in tissue perfusion.     

Fluid therapy with hydroxyethyl starch for massive blood loss during surgery

Purpose  

This clinical trial reports the use of hydroxyethyl starch (HES70/0.55/4) at very high dosages during surgery. HES70/0.55/4 has the lowest molecular weight among all HES products, and thus may have the least side effects. This observational retrospective study clarified the effects of high-dose HES70/0.55/4 on coagulation and renal function up to 1 month after massive bleeding during surgery.     

Fluid overload and outcomes in neonates receiving continuous renal replacement therapy

Background

Continuous renal replacement therapy (CRRT) has emerged as the modality of choice for the management of high-risk neonates with acute kidney injury (AKI), inborn errors of metabolism and multi-organ dysfunction. The aim of this study was to evaluate fluid overload (FO) and investigate the factors associated with outcomes in neonates undergoing CRRT.

Methods

We retrospectively reviewed the medical records of 34 neonates with AKI who were admitted to the neonatal intensive care unit (NICU) of Samsung Medical Center, Seoul, Republic of Korea between January 2007 and December 2014 where they underwent at least 24 h of CRRT.

Results

The survival rates of patients with an FO of?≥30 % at the time of CRRT initiation were lower than those of patients with an FO of?<30 % at the same time-point. Univariate Cox regression analysis revealed that a higher percentage FO at CRRT initiation and decreased urine output at the end of CRRT were associated with mortality, and multivariate Cox regression analysis indicated that mortality was associated with decreased urine output at the end of CRRT. Univariate linear regression analysis revealed that the length of hospital stay was associated with higher levels of serum creatinine at CRRT initiation, longer stay in the NICU prior to initiation of CRRT, longer duration of CRRT and lower body weight at the time of NICU admission.

Conclusions

Neonates with a higher percentage FO and higher levels of serum creatinine at CRRT initiation showed poor outcomes. Early initiation of CRRT before the development of severe FO or azotemia might improve the outcomes of neonates requiring CRRT.