Intravenous fluid administration and urine output during radical neck surgery

Fluid management in the cardiothoracic intensive care unit: diuresis--diuretics and hemofiltration

PURPOSE OF REVIEW

The present review discusses the current concepts of fluid management in cardiothoracic surgery, and its clinical implications with special reference to organ-related complications and their prevention.

RECENT FINDINGS

Current strategies in fluid management for cardiothoracic patients, various fluid formulation, and the preventive strategies for minimizing fluid-related complications are described, with particular reference to new discoveries and controversies that have arisen from recent literature.

SUMMARY

The optimal fluid management in cardiothoracic patients has not been settled. Results of recent clinical published trials highlight the need for minimizing fluid administration and attempting to use diuretics to achieve a negative fluid, although hypovolemia and hypoperfusion should be carefully considered. An individualized optimization of fluid status, using goal-directed therapy, has emerged as a possible preferable approach. The old debate between crystalloid and colloid solutions has been partially solved, as some colloids have demonstrated deleterious effect on renal function and coagulation system. Various preventive strategies have also emerged for minimizing fluid-related complications.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

[Perioperative fluid therapy]

Physiologic balance between fluids and electrolytes should remain stable during the perioperative period. Gaps in our understanding of how this balance is maintained has given rise to inappropriate management practices. Both failure to replace lost fluids and the infusion of excessive amounts can lead to serious consequences for the patient. There is currently renewed interest in studying the best use of fluids and/or blood products during and after surgery. This update of perioperative fluid therapy is based on a review of indexed literature retrieved by means of a PubMed search for the period of January 1999 through December 2009.

Plasma volume expanders and intraoperative fluid therapy

Adequate restoration of intravascular volume remains an important therapeutic maneuver in managing the surgical patient. Definition of the ideal volume replacement strategy still remains one of the burning problems. Firstly, the choice between colloid and crystalloid solutions continues to generate controversy. Secondly, the highly controversial crystalloid/colloid dispute has been enlarged to a colloid/colloid debate because of the increasing number of colloids that are available. And lastly, whether high or low volume replacement strategies are favorable for the surgical patient is an another issue for the anesthesiologists. Volume replacement has been hitherto often based on art, dogma and personal beliefs. It was the aim of this overview to present the different solutions and to facilitate the strategies for above three main issues in the field of intraoperative fluid therapy.

Interventions for protecting renal function in the perioperative period

BACKGROUND

A number of methods have been used to try to protect kidney function in patients undergoing surgery. These include the administration of dopamine and its analogues, diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors and hydration fluids.

OBJECTIVES

For this review, we selected randomized controlled trials which employed different methods to protect renal function during the perioperative period. In examining these trials, we looked at outcomes that included renal failure and mortality as well as changes in renal function tests, such as urine output, creatinine clearance, free water clearance, fractional excretion of sodium and renal plasma flow.

SEARCH STRATEGY

We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2), MEDLINE (1966 to June, 2007), and EMBASE (1988 to June, 2007); and handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery).

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery where a treatment measure was used for the purpose of renal protection in the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 53 studies for inclusion in this review. As well as data analysis from all the studies, we performed subgroup analysis for type of intervention, type of surgical procedure, and pre-existing renal dysfunction. We undertook sensitivity analysis on studies with high and moderately good methodological quality.

MAIN RESULTS

The review included data from 53 studies, comprising a total of 2327 participants. Of these, 1293 received some form of treatment and 1034 acted as controls. The interventions mostly consisted of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, or selected hydration fluids. The results indicated that certain interventions showed minimal benefits. All the results suffered from significant heterogeneity. Hence we cannot draw conclusions about the effectiveness of these interventions in protecting patients' kidneys during surgery.

AUTHORS' CONCLUSIONS

There is no reliable evidence from the available literature to suggest that interventions during surgery can protect the kidneys from damage. There is a need for more studies with high methodological quality. One particular area for further study may be patients with pre-existing renal dysfunction undergoing surgery.

Determinanten des insensiblen Flüssigkeitsverlustes

Accurate perioperative fluid balance is the basis of a targeted infusion regimen. However, neither the initial status nor perioperative changes of the fluid compartments can be reliably measured in daily routine. In particular, insensible losses are not consistently assessed, so that substitution therapy is generally empirical. The object of this paper is to communicate the scientific data on this topic. Preoperative fasting (10 h) does not per se cause intravascular hypovolemia. In adults, total basal evaporation by way of the skin and airways and of any wounds during major abdominal interventions is usually less than 1 ml/kg/h. An inconstant fluid and protein shift towards the interstitial space perioperatively seems to be associated with hypervolemia, which suggests it should be preventable. The decisive factor in this context seems to be deterioration of the endothelial glycocalyx, whose further patho-physiological impact is currently only partially known. Clinical studies have revealed a link between fluid restriction and improved outcome after major abdominal surgery.

Perioperative fluid management: current consensus and controversies

The scientific knowledge base that supports clinical decisions about perioperative fluid management continues to evolve. However, despite these advancements in the understanding of the physiology of fluid replacement, the definition of ''optimal'' perioperative fluid management remains a matter of clinical judgment. With an appreciation of the many factors, both sensible and insensible, that contribute to changes in blood and extracellular fluid volume during surgery, clinicians have tried to create reproducible and generally applicable formulas for replacement of fluid during surgery. These formulas have been challenged recently by the introduction of new tools for monitoring cardiopulmonary function, by the implementation of monitor-guided protocols for fluid management, and, more recently, by clinical data suggesting that fluid restriction may improve surgical outcomes in some clinical settings. The relative ease of pre-identified fluid replacement protocols is being slowly replaced by data-guided interventions that take into account a variety of factors. Clinicians are therefore required to tailor their fluid replacement strategies based on preoperative patient characteristics, the type of surgery and even the type of anesthetic that is utilized. Some of the benefits of this new approach range from relatively ''minor'' outcomes such as diminished nausea after surgery to preventing postoperative complications such as wound breakdown and cardiopulmonary failure.

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.

Perioperative fluid management and clinical outcomes in adults

The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the physicochemical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults.