Continuing Education ActivityHospitalized patients often have conditions that impair their ability to regulate their hydration status. Improper fluid management leads to significant morbidity and mortality. Thoughtful consideration of the type and amount of fluid required for each patient is crucial. This activity reviews the evaluation and treatment of patients’ fluid needs and highlights the importance of an interprofessional team managing patients in shock. Show
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Access free multiple choice questions on this topic. IntroductionFluid management is a critical aspect of patient care, especially in the inpatient medical setting. What makes fluid management both challenging and interesting is that each patient demands careful consideration of their individual fluid needs. Unfortunately, it is impossible to apply a single, perfect formula universally to all patients. However, one general principle for all patient scenarios is to replace whatever fluid is being lost as accurately as possible. These fluid losses can differ depending on patients’ medical conditions and differ by both volume and composition. For example, a patient admitted to the hospital with severe burns will have much greater fluid losses than a relatively healthy patient who is allowed nothing by mouth and awaiting a procedure. A patient admitted for dehydration from severe diarrhea might require different fluid compositions than a patient admitted in hypovolemic shock from a brisk upper gastrointestinal (GI) bleed. An important distinction in managing fluids is differentiating between maintenance fluids and fluid replacement. Maintenance fluids should address the patient's basic physiologic needs, including both sensible and insensible fluid losses. Sensible fluid losses refer to typical routes of excretion such as urination and defecation. Insensible losses refer to other routes of fluid loss, such as in sweat and from the respiratory tract. Fluid replacement goes beyond the normal physiologic losses and includes such conditions as vomiting, diarrhea, or severe cutaneous burns. One must consider these 2 categories of fluid loss separately when devising a fluid management strategy for an individual patient. IndicationsFluid management is an essential aspect for any patient admitted to the hospital. If possible, patients should take fluids enterally since this is the natural route of fluid intake. However, many patients who are sick enough to need admission to the hospital might have a reason they cannot tolerate oral intake. Alternative routes of administration such as intravenous access can deliver fluids directly to the vascular system. There are many ways to assess a patient’s volume status to determine their fluid needs. Often, one can determine the patient’s fluid status clinically based on a variety of physical exam findings and objective data from their vital signs. Laboratory markers are helpful as adjunctive data. The following is a list of findings that can help determine whether a patient is fluid-depleted or volume overloaded.[1] Vital Signs
Physical Exam Findings
Laboratory Findings
EquipmentIntravenous (IV) Fluid Solutions
Enteral Tubes
Enteral Fluid Solutions
PreparationThe pediatric population demands careful consideration of a child’s size in determining their rate of fluid maintenance. A 3-month-old infant has much different fluid needs than those of a more fully grown 8-year-old child. In many cases, a simple calculation called the 4-2-1 rule can determine the hourly rate of fluid maintenance required for a child based on weight.[2] The following example shows an application of this formula.
For example, a 22kg child would have the following maintenance fluid requirements.
Another commonly used formula predicts fluid needs over a 24-hour period. The following example shows an application of this formula.
For example, a 70-kg man would have the following maintenance fluid requirements.
One must exercise caution in applying these weight-based formulae to patients who are elderly or obese.[3] Unfortunately, no standardized guidelines exist at this point to guide adult maintenance intravenous therapy. It is beyond the scope of this article to delve into the nuances of deciding between various tonicities and volumes of fluid administration. These choices demand clinical judgment based on the initial fluid status of the patient and predictions of ongoing fluid needs. The electrolyte derangements discussed below in the complications section show potential issues arising from certain fluid choices. TechniqueThe strategy of managing a patient’s fluid differs depending on each patient’s clinical condition. If there can drink adequate fluid volumes by mouth, this should be the first choice. Some patients can tolerate other enteral options, such as feeding tubes. IV plus oral orders are effective for those unable to meet their total daily fluid requirements enterally. Nursing staff can titrate the ratios accordingly, depending on the patient’s ability to drink. Vital signs, physical exam, and adjunctive laboratory findings mentioned previously will show if each patient's fluid management strategy is appropriate. For example, a post-surgical patient with a new ileostomy might have additional fluid output from the stoma, which clinicians must factor into the overall fluid management strategy. ComplicationsElectrolyte Derangements Hyponatremia Monitor serum sodium regularly. This is more of a risk when using hypotonic solutions. Many patients admitted to the hospital have risks of baseline elevated antidiuretic hormone (ADH) release leading to volume retention and worsening hyponatremia.[4] Isotonic fluids are preferred for maintenance fluids in patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Risks of hyponatremia include cerebral edema with potentially dangerous neurologic sequelae such as seizures. If significant hyponatremia develops, it is important not to correct the serum sodium too quickly to avoid the devastating neurologic complication of central pontine myelinolysis.[5] Hyperkalemia Patients with renal failure who receive a potassium-containing solution might not handle clearing the potassium load and develop life-threatening hyperkalemia causing cardiac arrhythmias. Volume Overload Monitor for peripheral edema, pulmonary edema, or hepatomegaly. It is important to consider underlying cardiac dysfunction or renal failure and adjust volumes of administration accordingly. These patients might require a lower maintenance fluid rate than expected for their body weight. Metabolic Acidosis Normal saline is a slightly acidic solution relative to normal body pH. This can precipitate metabolic acidosis.[6] Lactated ringers solution is a closer approximation to normal body pH; however, the use of lactated ringers vs. normal saline for fluid maintenance administration often depends on availability at each hospital institution and is an evolving paradigm undergoing discussion nationally. Clinical SignificanceUnderstating the importance of proper fluid management is difficult. Careful consideration of each patient’s current clinical status and relevant past medical history when determining a fluid management strategy is crucial to avoid iatrogenic problems such as dehydration, volume overload, electrolyte derangements, or pH imbalances. Close communication between all members of the healthcare team can mitigate these issues. Enhancing Healthcare Team OutcomesFluid management is best managed through the efforts of an interprofessional healthcare team. Interprofessional discussion within the healthcare team can optimize proper fluid management for patients admitted to the hospital.[7] Bedside nurses often spend more time than any other healthcare member at the bedside with their patients and can provide useful assessments of patients’ volume status through documentation of vital signs and frequent visual assessments. Nurses can also help assess patients’ ability to tolerate enteral fluids and encourage patients to drink by mouth if there is no NPO order, which would prevent them from doing so. Nutritionists and dietitians help determine caloric needs for patients to ensure that they meet their metabolic demands, which are especially important during acute illnesses so that the body can heal properly. This is especially important in the pediatric population for infants who drink breast or formula. Pharmacists can recommend optimal fluid replacement formulations via IV, along with working with nutritionists for total parenteral nutrition (TPN). TPN is sometimes necessary as a temporizing measure for patients unable to take enteral fluid intake, but it comes with various challenges, such as the need for central venous access and the risk of central line-associated bloodstream infections (CLABSI). In the end, only with a complete interprofessional approach to fluid management can patient outcomes be optimized. [Level 5] Review QuestionsReferences1.Friedman JN, Goldman RD, Srivastava R, Parkin PC. Development of a clinical dehydration scale for use in children between 1 and 36 months of age. J Pediatr. 2004 Aug;145(2):201-7. [PubMed: 15289767] 2.Chesney CR. The maintenance need for water in parenteral fluid therapy, by Malcolm A. Holliday, MD, and William E. Segar, MD, Pediatrics, 1957;19:823-832. Pediatrics. 1998 Jul;102(1 Pt 2):229-30. [PubMed: 9651436] 3.Shafiee MA, Bohn D, Hoorn EJ, Halperin ML. How to select optimal maintenance intravenous fluid therapy. QJM. 2003 Aug;96(8):601-10. [PubMed: 12897346] 4.Miller M. Syndromes of excess antidiuretic hormone release. Crit Care Clin. 2001 Jan;17(1):11-23, v. [PubMed: 11219224] 5.Norenberg MD. Central pontine myelinolysis: historical and mechanistic considerations. Metab Brain Dis. 2010 Mar;25(1):97-106. [PubMed: 20182780] 6.Kraut JA, Madias NE. Treatment of acute metabolic acidosis: a pathophysiologic approach. Nat Rev Nephrol. 2012 Oct;8(10):589-601. [PubMed: 22945490] 7.Grainger JT, Maeda Y, Donnelly SC, Vaizey CJ. Assessment and management of patients with intestinal failure: a multidisciplinary approach. Clin Exp Gastroenterol. 2018;11:233-241. [PMC free article: PMC6003282] [PubMed: 29928141] How does dehydration affect acid base balance?The acid/base connection
When your electrolyte levels are out of balance due to dehydration, you experience an acid/base (pH) imbalance. Specifically, your pH levels decrease, creating metabolic acidosis. Symptoms include confusion, fatigue, headache and increased heart rate.
What electrolyte imbalance causes metabolic acidosis?Serum Electrolytes (Sodium, Chloride, Potassium, Magnesium, Phosphorus, Bicarbonate) Metabolic acidosis results either from the increased production or decreased excretion of nonvolatile acids or from the loss of body alkali.
Which condition may result in excessive metabolic acids in the body of the patient?Acidosis is a condition in which there is too much acid in the body fluids. It is the opposite of alkalosis (a condition in which there is too much base in the body fluids).
Which conditions can cause metabolic acidosis select all that apply?It can be caused by:. Cancer.. Carbon monoxide poisoning.. Drinking too much alcohol.. Exercising vigorously for a very long time.. Liver failure.. Low blood sugar (hypoglycemia). Medicines, such as salicylates, metformin, anti-retrovirals.. MELAS (a very rare genetic mitochondrial disorder that affects energy production). |