By the end of postgraduate training, using a patient-centred approach and appropriate selectivity, a resident, considering the patient’s cultural and gender contexts, will be able to...
Dehydration Key Feature 1: When assessing the acutely ill patient, look for signs and symptoms of dehydration. (ex: look for dehydration in the patient with a debilitating pneumonia). Skill: Clinical Reasoning Phase: Hypothesis generation Key Feature 2: In the dehydrated patient, assess the degree of dehydration using reliable indicators (ex: vital signs) as some patients' hydration status may be more difficult to assess (ex: elderly, very young, pregnant). Skill: Clinical Reasoning Phase: Physical, Investigation Key Feature 3a: In a dehydrated patient: Determine the appropriate volume of fluid for replacement of deficiency and ongoing needs. Skill: Clinical Reasoning Phase: Treatment, Diagnosis Key Feature 3b: In a dehydrated patient: Use the appropriate route (oral if the patient is able; IV when necessary). Skill: Clinical Reasoning Phase: Treatment Key Feature 4: When treating severe dehydration, use objective measures (ex: lab values) to direct ongoing management. Skill: Clinical Reasoning Phase: Investigation, Treatment Key Feature 5: In a dehydrated patient: Treat the precipitating illness concurrently. Skill: Clinical Reasoning Phase: Treatment Key Feature 6: Treat the dehydrated pregnant patient aggressively, as there are additional risks of dehydration in pregnancy. Skill: Clinical Reasoning, Selectivity Phase: Hypothesis generation, Treatment Diarrhea Key Feature 1a: In all patients with diarrhea: Determine hydration status. Skill: Clinical Reasoning Phase: Diagnosis Key Feature 1b: In all patients with diarrhea: Treat dehydration appropriately. Skill: Clinical Reasoning Phase: Treatment Pneumonia Key Feature 2: In a patient with signs and symptoms of pneumonia, do not rule out the diagnosis on the basis of a normal chest X-ray film (ex: consider dehydration, neutropenia, human immunodeficiency virus [HIV] infection). Skill: Clinical Reasoning, Selectivity Phase: Diagnosis, Hypothesis generation Key Feature 3: In a patient with a diagnosis of pneumonia, assess the risks for unusual pathogens (ex: a history of tuberculosis, exposure to birds, travel, HIV infection, aspiration). Skill: Clinical Reasoning Phase: History, Hypothesis generation Today I encountered a 9 year female with congenital muscular dystrophy who was presenting with an acute cough, vomiting, and diarrhea. She looked unwell, and dehydrated, and on lung exam she had decreased breath sounds on one side of her lungs compared to the other. Chest xray revealed a middle lobe pneumonia. What are the signs and symptoms of dehydration? Late signs
Early signs
Evaluating someone's volume status (i.e., whether they are hypovolemic, euvolemic, or hypervolemic) is a clinical assessment; there are no tests that can specifically tell you whether or not someone is dehydrated or fluid-overloaded. It's all about considering various clinical indicators of volume status, and different patient factors can make certain indicators more or less useful. For example, in the very young patient, the degree to which their anterior fontanelle is filled, from bulging to very sunken, can be a very useful indicator of volume status, but this is not useful once the anterior fontanelle is closed, which is usually the case by the age of 2. Whereas in the elderly patient with wrinkled skin, using skin turgor to assess degree of dehydration is pretty well useless. And when it comes to the patient who is pregnant, a high index of suspicion is needed because there are many physiologic adaptations to pregnancy that may mask early signs of dehydration. Furthermore, the ramifications could be as significant as dehydration inducing uterine cramping and preterm labour, or could manifest in long-term complications related to impairments in fetal growth and development; a lower threshold to begin a rehydration regimen can have a significant benefit-to-risk ratio. Vital signs are a useful component of the evaluation of volume status as they are objective (including, in the pregnant patient, fetal heart rate +/- amniotic fluid volume assessment by ultrasound), but by themselves they may not be sufficient enough to determine volume status as abnormal vital signs can be a reflection of much more than volume status. For example, a dehydrated patient could be expected to be tachycardic, but tachycardia can also be caused by fever, or hyperthyroidism, or anxiety, or pain, etc. So the vital signs must be interpreted in the clinical context as well, much as the more subjective indicators of volume status need to be. When a patient is determined to be dehydrated, it's time to get them rehydrated while treating the precipitating cause, which for the above patient case meant to give antibiotic therapy for the pneumonia.* The approach to rehydration will depend on how dehydrated you think the patient is, and is generally clinically assessed as being mild, moderate, or severe. For any degree of degree of dehydration, from mild to severe, rehydration will consist of a replacement phase (to replace fluid debt; normal saline [NS] is always used) followed by maintenance (to replace ongoing losses; type of solution here will depend on context). The approach will also depend on patient factors, such as whether they are a pediatric or adult patient, whether they have comorbidities such as kidney disease or diabetes, whether there are any ongoing sources of fluid loss (ex: diarrhea, vomiting, sweating), and if they have an electrolyte disturbance. Note that most people walking around in the world are maintaining their fluids orally, and in general this is the preferred approach. In the severely dehydrated patient, however, oral replacement just won't suffice, and so intravenous fluid resuscitation is always indicated in this situation. In the moderately dehydrated patient, it is still very important to replace their fluid debt, but the situation is not as critical, at least not yet. If the patient is tolerating oral fluids and is well enough to drink lots of fluid, instead of automatically initiating intravenous fluid replacement, you may wish to consider a trial of oral rehydration first (if it would be feasible given the reason for the dehydration and the patient's ability to compensate). And then, if the patient is tolerating oral fluids, it's always best to try replacing fluid debt orally if the severity of the dehydration is nothing more than mild. It goes without saying (but I'll say it anyway for completion) that anyone who can tolerate oral fluids definitely does not need intravenous replacement (unless ongoing losses are so extreme that the patient just can't keep up). In this latter situation, the patient would be like everyone else who compensates for typical water loss in a day by taking in enough fluid in food and drinks to compensate for fluid lost in urine, stool, perspiration, and insensible losses (from the skin and respiratory tract). Sometimes this would be the only intervention that would be keeping a patient in hospital, and with patients/caregivers who you expect will be reliable to follow-up if things are not improving or worsening, it is a waste of health care resources and is usually less pleasant for the child who could otherwise be more comfortable in their own bed. Generally, patients who are assessed for urgent or emergent medical issues and who are deemed safe to follow-up as an outpatient may be discharged for outpatient management. This is preferred by most patients and healthcare providers, the latter of whom are also familiar with the real possible of secondary nosocomial illness secondary to hospital admission. For the patient with mild to moderate dehydration who is a candidate for oral rehydration therapy, is any fluid okay? Well any fluid is better than no fluid, but some fluids are better than others. In particular, the World Health Organization recommends Oral Rehydration Solution, which is a specific mixture of water, glucose, and salt. Because water follows sodium, if we have sodium in the solution, then as this is taken up by the gastrointestinal tract, more water will also get absorbed. There are also receptors in the gut that take up more sodium when glucose is present (sodium-glucose transport proteins), and so by adding in glucose as well, the uptake of water is even greater. To make your own Oral Rehydration Solution, combine 1L of water with a half of a teaspoon (2.5 mL) of salt and 2 tablespoons (30 mL) of sugar. Alternatively, there are products that can be purchased other-the-counter from pharmacies. For those in whom oral rehydration therapy will not suffice, IV fluids are indicated. Below are my approaches to rehydration in adult and pediatric patients, respectively, when IV fluids are required. Adult
Pediatric
All this talk of fluid replacement is getting me thirsty! *Note that while this patient presented with x-ray evidence of pneumonia, many dehydrated patients may have a falsely negative chest x-ray early on in the disease process, which may also be the case for patients who are immunocompromised. If suspected clinically and the patient has risk factors for being unable to mount a swift early immune response, consider the need for empiric treatment for suspicion of pneumonia to prevent patient decompensation/deterioration. It's also important to consider risk factors a patient may have for acquisition of unusual pathogens, as may also occur in the patient who is immunocompromised or who has had unusual exposures to animals or other environments through travel. In the elderly or neurologically/cognitively compromised patients, consider their risk of chemical pneumonitis from aspiration. These risk factors matter because they influence choice of antibiotic.
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