Hydration Management In Acute Stroke Patients

本文主要講述了對于腦卒中的水化管理。文中主要以下幾個方面進(jìn)行講述：保濕平衡和營養(yǎng)/電解質(zhì)平衡-測量/控制并發(fā)癥鼻胃腸道-腦卒中患者影響我們生活-法律和其他方面。

Introduction

Stroke is a global public health concern with many sufferers presenting with varying levels of confusion (Oh and Seo 2007). Management of hydration in acute stroke patients is not standardised and variations in practice can be very wide between different continents. The sheer number of possible comorbidities and the relative ease with which hydration can trigger concomitant problems can lead to increasing incidence and prevalence of long-term patient care resulting from inadequate hydration management. Optimum hydration assessment and management are key clinical activities; however, inadequate hydration controls by health professionals persist (Oh and Seo 2007). Research shows that to guide fluid management to desired levels, a regular assessment of the volume status has to be made

Scope

This literature review is based on works that are found on Medical Literature Analysis and Retrieval System Online (MEDLINE), the Cumulative Index to Nursing and Allied Health literature (CINAHL), Cochrane, Department of Health (DoH), National Institute of Clinical Excellence (NICE), National Medical Council (NMC), World Health Organisation (WHO), Wiley Interscience and CKS databases that relate to hydration in stroke patients and nursing awareness of hydration in stroke patients. There is wide literature on different aspects of stroke and many authors have studied the effects of hydration in stroke patients. This review looks at literature that discusses management of hydration and/or the impacts of variations in hydration management on acute stroke patients' outcomes - like method of feeding, time- compliance in taking readings or measurements, legal issues and ethical issues.

Relevance to clinical practice

This literature review looks at relevant studies by experts that are found on credible databases. The purposes of the expert studies are reviewed and analysed to inform better understanding of current nursing practice in hydrating acute stroke patients. Several studies on hydration highlight specific difficulties relating to the assessment and management of hydration in acute stroke patients. There are differences between the management and the assessment of hydration in different hospitals and these complicate improving awareness of managing hydration for nurses in practice. If optimum hydration is directly linked to improved outcomes in acute stroke patients, research will be required to identify and overcome barriers to effective hydration management, including the development of specific tools (and knowledge base) to facilitate interventions that promote optimum hydration in seeking improved outcomes in acute stroke patients.#p#分頁標(biāo)題#e#

Methods of search and documentation

n on-line literature search of MEDLINE, CINAHL, COCHRANE, DOH, NICE, NMC, WHO and CKS from 1999 to May 2009 failed to identify enough relevant articles on hydration in stroke patients. Other sources were then reviewed for available literature on medical journals including the BMJ and American Family Physician. For the on-line computer-based literature searches, the following keywords were used: stroke, fluid balance, hydration, cerebrovascular accident (CVA), dehydration, stroke outcome, cerebrovascular disorders, medical management, artificial nutrition and hydration, dysphagia, dysphasia, pyrexia, acute brain infarction, enteral tube feeding, fluid and electrolyte balance, neurology, withholding treatment, pathophysiology and nurses and hydration

Hydration and hydration management in acute stroke patients

This literature review looks at one of the issues encountered globally in the treatment of acute stroke patients - optimum hydration. It takes a particular look at the nursing awareness, measurement, assessment, methods of intervention and the legal issues associated with hydration in acute stroke patients. Stroke is a debilitating condition and can be caused by an ischaemic event or a subarachnoid/intracerebral bleeding. Stroke patients usually present in hospital with co-morbidities (Oh and Seo 2007). Variations exist in stroke fatalities across geographical regions even within the same continent. Studies by Bhalla et al (2003) across four European centres (London, Dijon, Erlangen and Warsaw) have shown significant variation (after adjusting for case mix) in stroke case fatality, in incontinence, dysphasia, dysphagia, conscious level, pyrexia, hyperglycaemia and comorbidity. There were also significant intervention differences between centres in intravenous fluid use, enteral feeding, initiation of new antihypertensive therapy and insulin therapy, with the London centre having the lowest uptake of interventions. In another European BIOMED Programme, significant variations in case fatality for stroke between European centres (after adjustment for stroke severity) were observed, with the United Kingdom (UK) centres having the highest case fatality and the lowest levels of independence (Wolfe et al., 1999). There were lower intervention rates in the UK centre to correct abnormal physiological parameters in the acute phase which may reflect a difference in philosophy of acute medical supportive care compared with other European countries (Wolfe et al., 2001). Awareness of optimal hydration balance and assessment of the patient's hydration condition (in the care of acute stroke patients) is a fundamental part of critical care nursing and optimising the hemodynamic situation can be seen as a team-effort. One of the important factors determining quality of the circulation is the amount of circulating blood (Hoff et al 2008). Following a stroke, patients may have swallowing impairment and other changes of the gastro-intestinal (GI) tract that could affect nutritional and hydration status and that lead to aspiration pneumonia (Schaller et al 2006). Such changes affect the ability of the acute stroke patient to lead a normal nutritional life. Although the Schaller et al (2006) work did not show a direct link between hydration and other comorbidities, they agree that impaired hydrational status is associated with reduced functional improvement, increased complication rates, and prolonged hospital stays.#p#分頁標(biāo)題#e#

Hydration and hydration status

Hydration balance is a measure of the body's ability to manage fluids and electrolytes. In order to identify the urgency of interventions, nursing staff should characterize an individual's fluid and electrolyte imbalance as mild, moderate, or severe based on pertinent information including lab tests and other relevant criteria. It is important to recognize that the main electrolyte in extracellular fluid (ECF) is sodium and that of intracellular fluid (ICF) is potassium (Edwards, 2001). Toto (1998) pointed out that large increases or decreases in fluid volume can cause infarct, coma and confusion. This knowledge becomes significant in maintaining cerebral blood flow and in preventing secondary brain insult after an acute stroke. In a complication, respiratory or metabolic acidosis will promote the movement of potassium from the ICF and give rise to high serum potassium levels, which may affect cardiac function (Edwards, 2001). This phenomenon can be seen in many traumatic insults to the brain. A basic knowledge of this physiology in addition to the homeostatic mechanisms for fluid and electrolyte balance is a vital foundation for nursing practice, and essential to the nurse's role in hydration management. Cook et al (2005) highlighted the significance of fluids and hydration in the neuroscience patient and in Cook et al (2004) they highlighted that an understanding of the physiological mechanisms that surround stroke is important for nurses to monitor and treat such patients. Kelly et al (2004) in their study of dehydration and venous thromboembolism (VTE) after acute stroke believed dehydration after acute ischaemic stroke (AIS) is strongly independently associated with VTE, reinforcing the importance of maintaining adequate hydration in these patients. Their study of hydration over a 9-day period showed indication that dehydration was largely hospital acquired and that the association was causal. Although the possibility that VTE was already present at entry to hospital cannot be discounted, tests have shown that VTE is rarely present before the second day post stroke, and then it becomes increasingly prevalent over the next few days. This could be for one of many reasons including poor communication between patient and hospital staff, change of environment for the patient and the physiological impacts of stroke

Hydration balance and nutritional/electrolyte balance

The differences in how hydration is assessed in different hospitals have been subject of study for some time. The significance of fluid electrolyte homeostasis becomes very relevant in trauma and shock situations such as subarachnoid haemorrhage where an inflammatory response is triggered which causes a significant change in capillary membrane permeability in a short period of time. In such situations, water, electrolytes and albumin move into the interstitial space to permit the site of injury to receive the required factors (third space shift) (Edwards, 2001). A number of physiological mechanisms are required to maintain homeostasis of hydration status, all of which inform proactive nursing assessment, intervention and evaluation. Those with trauma to the nervous system are vulnerable to disruption to the homeostasis of fluid and electrolyte balance (Cook 2005). Older adults may have a poorer capacity to adapt to shifts in acute fluid balance, leading to the possibility of cardiac and renal functions being impaired and, as a result, a lower glomerular filtration rate (Sheppard, 2001). Managing the fluid balance of the stroke patient by intake and output measures needs to be exercised cautiously because even though the patient's fluid volume may not have changed, his/her circulatory volume may be significantly lower in instances of major trauma (Edwards, 2001) Good hydration has been shown to reduce the risk of urolithiasis (category Ib evidence) (see Appendix 2), constipation, exercise asthma, hypertonic dehydration in the infant, and hyperglycemia in diabetic ketoacidosis (all category IIb evidence), and is associated with a reduction in urinary tract infections (UTIs), hypertension, fatal coronary heart disease, venous thromboembolism, and cerebral infarct#p#分頁標(biāo)題#e#

Complications of measurement/control - Naso-gastric v PEG, enteral v parentera

Patient history taking on presenting in the hospital differs from hospital to hospital. History taking should include assessment of fluid intake and loss, baseline hydrational status, skin turgor, heart rate, blood pressure and urinary output. Normal fluid intake for the average adult is approximately 2-2.5 litres, obtained from food, fluids or metabolic by-products (Edwards, 2001). Methods of measurement are not standardised across hospital settings with Wise et al (2000) showing that faecal fluid losses are often neglected in daily fluid balance charts with the possibility of inaccurate hydration assessment. Fluid assessment must include estimating, as accurately as possible, the quantity of fluid taken in. It must take into consideration the entire processes by which water, potassium and sodium are obtained. Measurements are often mainly focused on the extremes of hydration (optimal hydration and extreme dehydration) and this should not be the case. Assessment of hydrational status and need is continuous and begins somewhere along a continuum of severe hypovolaemia/ dehydration to severe hypervolaemia/ overhydration. In looking at dehydration, not only extreme dehydration should be noted. Manz and Wentz (2005) highlight that there is increasing evidence mild dehydration may also account for many morbidities and play a role in various other morbidities. The way in which stroke is managed acutely, such as measures maintaining physiological homeostasis may also vary between different populations (Bhalla et al 2003). The physiological indicators of acute deficits in fluid balance may be masked in individuals where compensatory mechanisms are intact. A history of acute events, mainly from baseline documentation and history taking, may enable better identification of such imbalances (Sheppard, 2001). Fluid and electrolyte homeostasis is brought about by the interaction between the renal, pulmonary, neuroendocrine, integumentary and gastrointestinal systems (Edwards, 2001). According to (Cook 2005), fluid and electrolyte management is a fundamental aspect of the role of the neuroscience nurse. Artificial feeding and fluids are the options for a patient who has an advanced, life-threatening illness and is dying. The patient, family members and doctor can talk about these options and the benefits and risks (Ackermann 2000). Hydration and electrolyte status are crucial mediators to the extent of the neuro-hormonal response to trauma. Edwards (1998, 2001) highlighted that homeostasis is maintained by a constant movement of water, sodium and potassium between intra- and extracellular compartments. While the movement of water and electrolytes between the cellular compartments is highly significant, it is important to recognize that in acute and chronic illness intracellular fluid (ICF) is reduced and extracellular fluid (ECF) increased almost to the extreme (Edwards, 2001). This is highly relevant for cerebral metabolism, because transport of oxygen, glucose, proteins and other products for cellular metabolism and their by-products may be severely impaired. Stroke may affect one's level of alertness, perception of thirst, ability to access liquids, and ability to swallow them when offered. Stroke victims with such impairments may be at increased risk for diuretic-induced dehydration (Churchill et al 2004). Managing hydration balance is of crucial importance and the mechanisms for the adequate monitoring and controls need to be in place. Nursing management questions in the assessment of hydration in acute stroke patients should include whether use of intravenous fluids during the first week of stroke was recorded. Questions should also include whether the patient was fed orally, by nasogastric tube, through percutaneous gastrostomy tube, by intravenous methods or not at all? The fact that these questions can be raised enforces the need for adequate documentation and recording of acute stroke patient records. Bhalla et al (2002) says that the use of artificial ventilatory support with intubation or nasal intermittent positive pressure ventilation should be documented as well as the use of supplemental oxygen given through nasal catheters or masks. Enteral tube feeding is a vital means of feeding and balancing hydration levels in patients with stroke. There are no set standards for hospitals in the UK and hospitals have recorded much variation between them in the timing of the start of enteral tube feeding and whether a nasogastric or percutaneous endoscopic gastrostomy (PEG) tube is used (Ebrahim and Redfern 1999). Some clinicians delay tube feeding for 2 weeks or more, and although early nutrition is unlikely to be harmful, whether any nutritional benefits offset the difficulties and complications of initiating and maintaining early enteral tube feeding is unclear. If the timing or route of enteral tube feeding does affect outcome, the present variation in practice means that large numbers of patients are being denied best treatment. Whether enteral tube feeding via PEG rather than nastrogastric tube or early initiation of enteral tube feeding improve outcomes was tested in the FOOD trials and no evidence of significant benefit from PEG rather than nasogastric tube feeding was found. Neither was any hazard from early tube feeding found (The FOOD collaboration 2003). The explanation for any difference between PEG and nasogastric groups is not clear, but one factor might be the effect of a long-term PEG tube on dependency since more patients in the PEG group were still receiving such tube feeding than in the nasogastric group at follow-up (The FOOD collaboration 2003). The survivors in the PEG group were also more likely to be living in institutions and had lower quality of life. Another intriguing finding was the excess of pressure sores in the PEG group, raising the possibility that those with such tubes might move less or be nursed differently. Weaknesses in this test results include insufficient statistical power to exclude more modest differences between groups; no information about the proportion of eligible patients enrolled in each centre; our use of an informal (although reliable and highly predictive) assessment of nutritional status; absence of precise monitoring of patients' daily intake of nutrients (rather than fluids); absence of on-site source data verification or collection of information on changing nutritional status (e.g. in-hospital weights); possible bias due to masking of secondary outcome measures. Although compliance was not 100%, this fact results from the inevitable difficulties of adhering to rigid schedules when patients' conditions change. Difficulties with nasogastric feeding in stroke patients (who are often confused and uncooperative) have led to increasing use of PEG tubes at an early stage. Enthusiasm for this method has been encouraged by the results of a trial that reported much lower case fatality rates in patients fed via PEG (13%) rather than nasogastric tube (57%) (The FOOD trial collaboration 2003). Due to significant alterations in fluid balance after enteral tube-feeding in patients, close attention to the recording of fluid balance such as intake/output measurements, body weights and simple bedside assessments is needed to detect fluid imbalances and other serious complications at an early stage (Oh and Seo 2007). One explanation for the varying and inconsistent readings in fluid hydration between enteral and PEG might #p#分頁標(biāo)題#e#

Stroke patients and the impacts of stroke on life

Difficulty with swallowing is a common problem in acute stroke patients, and can lead to aspiration pneumonia, dehydration, and exacerbation of any existing malnutrition (Finestone and Greene-Finestone 2003). In Oh and Seo (2007) the authors set out to examine the fluid and electrolyte complications after enteral tube feeding in acute brain infarction patients. The background is that inconsistencies in the results of the water and electrolyte complications associated with enteral tube feeding are partly because of uncontrolled disease-related variables. The implication is that these variables were not adequately managed. Stroke patients very often present with dysphagia and this is very commonly dehydration associated with undernutrition (The Food Trial 2005). Up to half of stroke patients in hospital have dysphagia, which precludes safe oral nutrition for the first few days and can persist for long periods (Mann et al 1999). Although a 50% prevalence can be considered to be high, the nutritional/fluid status of a stroke patient can rapidly deteriorate in hospital. The difficulty in feeding stroke patients with dysphagia coupled with the discomfort associated with stroke can exacerbate undernutrition and/or dehydration. Studies show that undernutrition shortly after admission is independently associated with increased case fatality and poor functional status at 6 months (The FOOD trial collaboration 2003). The current financial burden of efficiency savings and reduced budgets in the NHS hospitals results in reduced staff numbers so that patients can not be attended to on a one-on-one basis so that ensuring appropriate hydration levels is done by periodic but regular monitoring of charts. An option for the future in this area may be to involve the patients' family members in hydration monitoring and provide them with appropriate training if evidence can show that being around loved ones improves outcomes and early warnings. In acute stroke, artificial nutrition through an enteral route is needed because of dysphagia and since oral feeding is unsafe in some dysphagic patients, enteral nutrition is often administered as nasogastric or percutaneous endoscopic gastrostomy (PEG) tube feeding (Finestone and Greene-Finestone 2003). Naso-gastric tube feeding (a prevalent enteral method) has been reported to improve clinical outcomes more than the parenteral route in brain-injured patients (Rhoney et al 2002). Oh and Seo (2007) in their study used 85 subjects, but their work was limited by the fact that it was performed retrospectively and some of the subjects' records were incomplete. Also, because the patients in the study were from one hospital it is not conclusively known whether the results can be generalised to the whole population./p>

Legal and other aspects

Japanese physicians' attitudes towards artificial nutrition and hydration (ANH) as a life-sustaining treatment (LST) were examined to find out if they withhold or withdraw the LST when treating older adults with stroke-caused profound impairment with no hope for recovery. The study findings show that the informants held different views towards LST because most doctors considered ANH to be indispensable and ANH is automatically provided to patients (Aita and Kai 2006). With the advancement of medical technology, decisions to withhold or withdraw LST are among the most difficult to make for health professionals (British Medical Association 2001). Physicians caring for stroke patients often encounter comatose or semi-comatose patients with severe stroke for whom it is difficult to determine whether or not to continue care (Asplund and Britton, 1989). By administering LST, some patients in this patients' group, whose bodily functions other than brain function could remain stable, could potentially survive for months or years without achieving awareness or being able to interact with others (Aita et al 2008). Certain Japanese physicians have criticized the current efforts regarding life prolonging as Aita et al (2008) states: ''Prolonging the process of dying like this constitutes the violation of dignity and human rights. The life-prolongation only serves hospital operators who want to make profits by keeping hospital beds occupied.'' They also said this practice impacted the carers and that some nurses also ''feel emptiness toward the manipulative life-prolongation'' when taking care of these elderly patients. In the West, some countries have worked out nation-wide guidelines related to withholding or withdrawing LST that say stroke-caused profound impairment with no hope for recovery is a potential reason to withhold or withdraw LST (British Medical Association, 2001). Ackermann (2000) believes withholding and withdrawing therapy challenge family physicians to be excellent communicators with patients and families and recommends that family physicians should continue to be strong advocates for dying patients. Sprung et al (2003) highlighted differences between withholding and withdrawing therapy showing that withdrawal of therapy is followed by a nearer and more rapid death than withholding therapy, and that physicians and nurses were more inclined towards withholding rather than withdrawing therapy. Food and water are considered symbols of caring (Ackermann, 2000), therefore, it may be natural for physicians to give a special status to ANH as food and water. Whether to withdraw ANH from a patient in persistent vegetative state has also drawn substantial media attention in the U.S. (Casarett et al., 2005; Ganzini, 2006). The findings of the study also suggest that the physicians' double standard is partly based on their subjective judgment whether the treatment is ordinary or extraordinary. However, the standard of ordinary/extraordinary care has long been criticized as too vague to guide decision-makers in the U.S. (Beauchamp and Childress, 2001). It is believed the current legal framework has also inappropriately led some physicians to simply continue care regardless of the patients' conditions, thus resulting in putting an unnecessary burden on patients. The physicians' subjective interpretation of the current legal framework may lead to decisions not to initiate mechanical ventilation in some older adults for fear of facing a situation in which physicians cannot withdraw it at a later stage#p#分頁標(biāo)題#e#

Conclusion

Hypovolemia and hypervolemia occurred frequently after acute stroke but were often not recognized as such by nurses. The nurses' predictions of current volume status do not seem sufficiently reliable to serve as a basis for therapeutic decisions. More advanced techniques for bedside assessment of volume status may be indicated for optimizing volume status in patients with acute stroke (Hoff et al 2004). Whereas studies have looked at the optimal method of improving hydration, whether correcting dehydration in stroke improves outcome is not very clear. Given the complexity of the cell death cascade following brain ischemia, novel approaches and combination therapy are inevitable for victims of stroke (Fisher and Brott 2003). The review indicates that standards vary from country to country in the legal framework for withdrawing and withholding hydration and nutrition during end stage care.