Intravenous fluid therapy
Despite numerous studies on perioperative intravenous fluid therapy, there is insufficient evidence to draw definitive conclusions regarding fluid management in neurosurgical patients. Although evidence is still lacking, isotonic balanced crystalloid solutions should be considered the first-choice fluid, while hypotonic solutions should be avoided. Furthermore, colloid solutions should be used with caution, and their potential risks and benefits should be considered. To achieve an optimal fluid volume status while avoiding overhydration and excessive restriction, the amount and duration of fluid administration should be considered, and an individualized fluid strategy is recommended using GDFT based on dynamic fluid parameters 1).
It is essential in patients admitted to the intensive care unit (ICU) with traumatic brain injury. Wiegers et al. aimed to quantify the variability in fluid management policies in patients with traumatic brain injury and to study the effect of this variability on patients' outcomes.
They did a prospective, multicentre, comparative effectiveness study of two observational cohorts: CENTER-TBI in Europe and OzENTER-TBI in Australia. Patients from 55 hospitals in 18 countries, aged 16 years or older with traumatic brain injury requiring a head CT, and admitted to the ICU were included in this analysis. We extracted data on demographics, injury, and clinical and treatment characteristics, and calculated the mean daily fluid balance (difference between fluid input and loss) and mean daily fluid input during ICU stay per patient. We analysed the association of fluid balance and input with ICU mortality and functional outcome at 6 months, measured by the Glasgow Outcome Scale Extended (GOSE). Patient-level analyses relied on adjustment for key characteristics per patient, whereas centre-level analyses used the centre as the instrumental variable.
2125 patients enrolled in CENTER-TBI and OzENTER-TBI between Dec 19, 2014, and Dec 17, 2017, were eligible for inclusion in this analysis. The median age was 50 years (IQR 31 to 66) and 1566 (74%) of patients were male. The median of the mean daily fluid input ranged from 1·48 L (IQR 1·12 to 2·09) to 4·23 L (3·78 to 4·94) across centres. The median of the mean daily fluid balance ranged from -0·85 L (IQR -1·51 to -0·49) to 1·13 L (0·99 to 1·37) across centres. In patient-level analyses, a mean positive daily fluid balance was associated with higher ICU mortality (odds ratio [OR] 1·10 [95% CI 1·07 to 1·12] per 0·1 L increase) and worse functional outcome (1·04 [1·02 to 1·05] per 0·1 L increase); higher mean daily fluid input was also associated with higher ICU mortality (1·05 [1·03 to 1·06] per 0·1 L increase) and worse functional outcome (1·04 [1·03 to 1·04] per 1-point decrease of the GOSE per 0·1 L increase). Centre-level analyses showed similar associations of higher fluid balance with ICU mortality (OR 1·17 [95% CI 1·05 to 1·29]) and worse functional outcome (1·07 [1·02 to 1·13]), but higher fluid input was not associated with ICU mortality (OR 0·95 [0·90 to 1·00]) or worse functional outcome (1·01 [0·98 to 1·03]).
In critically ill patients with traumatic brain injury, there is significant variability in fluid management, with more positive fluid balances being associated with worse outcomes. These results, when added to previous evidence, suggest that aiming for neutral fluid balances, indicating a state of normovolemia, contributes to improved outcome 2).
Many adult inpatients need intravenous (IV) fluid therapy to prevent or correct problems with their fluid and/or electrolyte status. Deciding on the optimal amount and composition of IV fluids to be administered and the best rate at which to give them can be a difficult and complex task, and decisions must be based on a careful assessment of the patient’s individual needs. Errors in prescribing IV fluids and electrolytes are particularly likely in emergency departments, acute admission units, and general medical and surgical wards rather than in operating theatres and critical care units. Surveys have shown that many staff who prescribe IV fluids know neither the likely fluid and electrolyte needs of individual patients nor the specific composition of the many choices of IV fluids available to them. Standards of recording and monitoring IV fluid and electrolyte therapy may also be poor in these settings. IV fluid management in hospitals is often delegated to the most junior medical staff who frequently lack the relevant experience and may have received little or no specific training on the subject. The National Confidential Enquiry into Perioperative Deaths report in 1999 highlighted that a significant number of hospitalized patients were dying as a result of an infusion of too much or too little fluid. The report recommended that fluid prescribing should be given the same status as drug prescribing. Although mismanagement of fluid therapy is rarely reported as being responsible for patient harm, it is likely that as many as 1 in 5 patients on IV fluids and electrolytes suffer complications or morbidity due to their inappropriate administration. There is also considerable debate about the best IV fluids to use (particularly for more seriously ill or injured patients), resulting in wide variation in clinical practice. Many reasons underlie the ongoing debate, but most revolve around difficulties in interpretation of both trial evidence and clinical experience, including the following factors: Many accepted practices of IV fluid prescribing were developed for historical reasons rather than through clinical trials. Trials cannot easily be included in meta-analyses because they examine varied outcome measures in heterogeneous groups, comparing not only different types of fluid with different electrolyte content, but also different volumes and rates of administration and, in some cases, the additional use of inotropes or vasopressors. Most trials have been undertaken in operating theatres and critical care units rather than admission units or general and elderly care settings. Trials claiming to examine best early therapy for fluid resuscitation have actually evaluated therapy choices made after initial fluid resuscitation, with patients already in critical care or operating theatres. Many trials inferring best therapy for fluid resuscitation after acute fluid loss have actually examined situations of hypovolaemia induced by anesthesia. There is a clear need for guidance on IV fluid therapy for general areas of hospital practice, covering both the prescription and monitoring of IV fluid and electrolyte therapy, and the training and educational needs of all hospital staff involved in IV fluid management. The aim of this NICE guideline is to help prescribers understand the: physiological principles that underpin fluid prescribing; pathophysiological changes that affect fluid balance in disease states; indications for IV fluid therapy; reasons for the choice of the various fluids available and principles of assessing fluid balance. In developing the guideline, it was necessary to limit the scope by excluding patient groups with more specialized fluid prescribing needs. It is important to emphasize that the recommendations do not apply to patients under 16 years, pregnant women, and those with severe liver or renal disease, diabetes or burns. They also do not apply to patients needing inotropes and those on intensive monitoring, and so they have less relevance to intensive care settings and patients during surgical anesthesia. Patients with traumatic brain injury (including patients needing neurosurgery) are also excluded. The scope of the guideline does not cover the practical aspects of administration (as opposed to the prescription) of IV fluids. It is hoped that this guideline will lead to better fluid prescribing in hospitalized patients, reduce morbidity and mortality, and lead to better patient outcomes. Strategies for further research into the subject have also been proposed. The guideline will assume that prescribers will use a drug’s summary of product characteristics to inform decisions made with individual patients 3).