Fortes Matthew B, Owen Julian A, Raymond-Barker Philippa, Bishop Claire, Elghenzai Salah, Oliver Samuel J, Walsh Neil P
School of Sport, Health and Exercise Sciences, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom.
School of Sport, Health and Exercise Sciences, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom.
J Am Med Dir Assoc. 2015 Mar;16(3):221-8. doi: 10.1016/j.jamda.2014.09.012. Epub 2014 Oct 22.
Dehydration in older adults contributes to increased morbidity and mortality during hospitalization. As such, early diagnosis of dehydration may improve patient outcome and reduce the burden on healthcare. This prospective study investigated the diagnostic accuracy of routinely used physical signs, and noninvasive markers of hydration in urine and saliva.
Prospective diagnostic accuracy study.
Hospital acute medical care unit and emergency department.
One hundred thirty older adults [59 males, 71 females, mean (standard deviation) age = 78 (9) years].
Participants with any primary diagnosis underwent a hydration assessment within 30 minutes of admittance to hospital. Hydration assessment comprised 7 physical signs of dehydration [tachycardia (>100 bpm), low systolic blood pressure (<100 mm Hg), dry mucous membrane, dry axilla, poor skin turgor, sunken eyes, and long capillary refill time (>2 seconds)], urine color, urine specific gravity, saliva flow rate, and saliva osmolality. Plasma osmolality and the blood urea nitrogen to creatinine ratio were assessed as reference standards of hydration with 21% of participants classified with water-loss dehydration (plasma osmolality >295 mOsm/kg), 19% classified with water-and-solute-loss dehydration (blood urea nitrogen to creatinine ratio >20), and 60% classified as euhydrated.
All physical signs showed poor sensitivity (0%-44%) for detecting either form of dehydration, with only low systolic blood pressure demonstrating potential utility for aiding the diagnosis of water-and-solute-loss dehydration [diagnostic odds ratio (OR) = 14.7]. Neither urine color, urine specific gravity, nor saliva flow rate could discriminate hydration status (area under the receiver operating characteristic curve = 0.49-0.57, P > .05). In contrast, saliva osmolality demonstrated moderate diagnostic accuracy (area under the receiver operating characteristic curve = 0.76, P < .001) to distinguish both dehydration types (70% sensitivity, 68% specificity, OR = 5.0 (95% confidence interval 1.7-15.1) for water-loss dehydration, and 78% sensitivity, 72% specificity, OR = 8.9 (95% confidence interval 2.5-30.7) for water-and-solute-loss dehydration).
With the exception of low systolic blood pressure, which could aid in the specific diagnosis of water-and-solute-loss dehydration, physical signs and urine markers show little utility to determine if an elderly patient is dehydrated. Saliva osmolality demonstrated superior diagnostic accuracy compared with physical signs and urine markers, and may have utility for the assessment of both water-loss and water-and-solute-loss dehydration in older individuals. It is particularly noteworthy that saliva osmolality was able to detect water-and-solute-loss dehydration, for which a measurement of plasma osmolality would have no diagnostic utility.
老年人脱水会导致住院期间发病率和死亡率上升。因此，早期诊断脱水可能改善患者预后并减轻医疗负担。本前瞻性研究调查了常用体征以及尿液和唾液中水分含量的非侵入性标志物的诊断准确性。
前瞻性诊断准确性研究。
医院急性医疗护理单元和急诊科。
130名老年人[59名男性，71名女性，平均（标准差）年龄 = 78（9）岁]。
任何主要诊断的参与者在入院后30分钟内接受了水分含量评估。水分含量评估包括7种脱水体征[心动过速（>100次/分钟）、收缩压低（<100毫米汞柱）、黏膜干燥、腋窝干燥、皮肤弹性差、眼睛凹陷和毛细血管再充盈时间长（>2秒）]、尿液颜色、尿比重、唾液流速和唾液渗透压。血浆渗透压以及血尿素氮与肌酐比值被评估为水分含量的参考标准，21%的参与者被归类为失水性脱水（血浆渗透压>295毫摩尔/千克），19%被归类为水和溶质丢失性脱水（血尿素氮与肌酐比值>20），60%被归类为水分正常。
所有体征对检测任何一种脱水形式的敏感性都很差（0%-44%），只有收缩压低显示出有助于诊断水和溶质丢失性脱水的潜在效用[诊断比值比（OR）= 14.7]。尿液颜色、尿比重和唾液流速均无法区分水分状态（受试者工作特征曲线下面积 = 0.49 - 0.57，P > 0.05）。相比之下，唾液渗透压显示出中等诊断准确性（受试者工作特征曲线下面积 = 0.76，P < 0.001），可区分两种脱水类型（失水性脱水的敏感性为70%，特异性为68%，OR = 5.0（95%置信区间1.7 - 15.1）；水和溶质丢失性脱水的敏感性为78%，特异性为72%，OR = 8.9（95%置信区间2.5 - 30.7））。
除收缩压低有助于水和溶质丢失性脱水的特异性诊断外，体征和尿液标志物在确定老年患者是否脱水方面几乎没有用处。与体征和尿液标志物相比，唾液渗透压显示出更高的诊断准确性，可能对评估老年人的失水性脱水和水和溶质丢失性脱水有用。特别值得注意的是，唾液渗透压能够检测出水和溶质丢失性脱水，而血浆渗透压测量对此并无诊断效用。
