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胸骨角と右房の位置関係

体の傾斜角度にかかわらず、右房の5 cm高い位置に胸骨角がある。これを利用して、診察や超音波検査で内頸静脈の拍動点が観察できる高さと胸骨角を比較し、中心静脈圧を推定することができる(胸骨角レベルで拍動点を観察=推定中心静脈圧5 cmH2Oと判定)。
出典
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1: 編集部にて作図

高齢者の体液分布

脂肪には水分が少なく、筋肉には多く含まれる。そのため、筋量の少ない高齢者、女性は体内水分比率が小さく、体液欠乏に弱い。
出典
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1: Prevalence, risk factors and strategies to prevent dehydration in older adults.
著者: Wotton K, Crannitch K, Munt R.
雑誌名: Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.
Abstract/Text: The treatment of dehydration in older adults admitted from residential care to an acute hospital setting may lead to haemodynamic stability. There is however an increased risk for short or long term alterations in physiological, cognitive and psychological status and ultimately, decreased quality of life. Such acute care admissions could be decreased where preventative strategies tailored to address individual risk factors are combined with more frequent assessment of the degree of hydration. The questionable reliability of assessment criteria in older adults increases the need to use multiple signs and symptoms in the identification and differentiation of early and late stages of dehydration. This article reviews various risk factors, explores the reliability of clinical signs and symptoms and reinforces the need to use multiple patient assessment cues if nurses are to differentiate between, and accurately respond to, the various causes of dehydration. Specific strategies to maintain hydration in older adults are also identified.
Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.

高齢者における体液欠乏の危険因子

体液欠乏が問題になるときは複数の病態が併存していることが多く、それらを丁寧に拾い上げる必要がある。体液喪失に利尿薬などの薬剤が関与するときには、体液欠乏が回復するまで当該薬剤を休薬することが求められる。
出典
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1: Prevalence, risk factors and strategies to prevent dehydration in older adults.
著者: Wotton K, Crannitch K, Munt R.
雑誌名: Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.
Abstract/Text: The treatment of dehydration in older adults admitted from residential care to an acute hospital setting may lead to haemodynamic stability. There is however an increased risk for short or long term alterations in physiological, cognitive and psychological status and ultimately, decreased quality of life. Such acute care admissions could be decreased where preventative strategies tailored to address individual risk factors are combined with more frequent assessment of the degree of hydration. The questionable reliability of assessment criteria in older adults increases the need to use multiple signs and symptoms in the identification and differentiation of early and late stages of dehydration. This article reviews various risk factors, explores the reliability of clinical signs and symptoms and reinforces the need to use multiple patient assessment cues if nurses are to differentiate between, and accurately respond to, the various causes of dehydration. Specific strategies to maintain hydration in older adults are also identified.
Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.

人体における水分のコントロール

細胞外液の欠乏、自由水の欠乏のいずれも口渇を引き起こし、腎でのナトリウム再吸収などを介してホメオスタシスの維持を行う。
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1: 編集部にて作図

細胞外液欠乏と自由水欠乏の臨床的特徴

細胞外液の欠乏は主に有効循環血漿量の低下を招くため、起立性低血圧や腎機能低下などを招く。自由水の欠乏では高ナトリウム血症(高浸透圧血症)を生じるが、中枢神経以外の臓器障害は単独で生じることは少ない。
出典
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1: Volume depletion versus dehydration: how understanding the difference can guide therapy.
著者: Bhave G, Neilson EG.
雑誌名: Am J Kidney Dis. 2011 Aug;58(2):302-9. doi: 10.1053/j.ajkd.2011.02.395. Epub 2011 Jun 25.
Abstract/Text: Although often used interchangeably, dehydration and volume depletion are not synonyms. Dehydration refers to loss of total-body water, producing hypertonicity, which now is the preferred term in lieu of dehydration, whereas volume depletion refers to a deficit in extracellular fluid volume. In particular, hypertonicity implies intracellular volume contraction, whereas volume depletion implies blood volume contraction. Using a case of hyperglycemic hypertonic nonketosis as an example, we examine the changing composition of body fluid spaces to explore the distinction between dehydration and hypertonicity from volume depletion.

Copyright © 2011 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.
Am J Kidney Dis. 2011 Aug;58(2):302-9. doi: 10.1053/j.ajkd.2011.02.395...

Nohria-Stevenson分類

うっ血所見または/および低灌流所見の治療の必要性を判断する。
Nohria-Stevenson分類は、うっ血と低灌流という臨床所見のみから4つのプロファイルに分類したもの。スワン・ガンツカテーテルによるForresterの分類があるが、それを理学所見に基づいて分類したもので現場での判断に有用。dry-coldである場合は、脱水を意味し慎重に輸液を行う、Wet-warmであれば逆に溢水を意味するため利尿剤、血管拡張薬投与を考慮する。wet-coldであればカテコラミンなどの強心薬投与、機械補助などが考慮される。Dry-warmでは通常治療は必要ない。
なお、dryとは鬱血所見を認めないことを意味し、warmとは、低灌流所見を認めないことを意味する。
出典
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1: Evaluation and monitoring of patients with acute heart failure syndromes.
著者: Nohria A, Mielniczuk LM, Stevenson LW.
雑誌名: Am J Cardiol. 2005 Sep 19;96(6A):32G-40G. doi: 10.1016/j.amjcard.2005.07.019.
Abstract/Text: Advanced heart failure (HF) is associated with frequent hospitalizations, poor quality of life, and increased mortality. Despite optimal medical management, readmission rates remain high and account for approximately two thirds of all costs related to HF management. Evaluation of patients with HF is critical for the appropriate selection and monitoring of therapy as well as for the prevention of recurrent hospitalizations. This evaluation can be complex and relies on integration of the bedside evaluation and information available from invasive and other noninvasive diagnostic techniques. The clinical examination remains the cornerstone of HF evaluation. Key features of the history and physical examination can be used to assign hemodynamic profiles based on the absence or presence of congestion and adequacy of perfusion. These hemodynamic profiles provide prognostic information and may be used to guide therapy. Direct measurement of hemodynamics may be helpful in patients in whom the physical examination is limited or discordant with symptoms. Although the pulmonary artery catheter (PAC) is not recommended during routine therapy of patients hospitalized with HF, it is reasonable to consider the use of PAC monitoring to adjust therapy in patients who demonstrate recurrent or refractory symptoms despite ongoing standard therapy adjusted according to clinical assessment. This is particularly relevant in centers with experience in hemodynamic monitoring for HF. B-type natriuretic peptide (BNP) testing has been shown to facilitate diagnosis of the etiology of dyspnea in the urgent setting for patients without a prior diagnosis of HF. Furthermore, BNP levels provide important prognostic information in patients with chronic HF, but serial BNP testing has not been validated as a guide to inpatient or outpatient management. Echocardiographic assessment can provide prognostic information about ventricular function and size as well as information about hemodynamic status. Development of validated and reproducible noninvasive techniques to monitor patients with acute HF will be an important step in maximizing interventions to improve outcomes in this patient population.
Am J Cardiol. 2005 Sep 19;96(6A):32G-40G. doi: 10.1016/j.amjcard.2005....

自由水欠乏の推定式 

例えば、現体重60 kg、血清Na 150 mEq/Lの患者の自由水欠乏は150/140×60×0.5-60×0.5=4.2 Lと推定される。
ただし、この式では並存する細胞外液(Na)の欠乏を考慮していないことに注意が必要である。
出典
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1: Understanding clinical dehydration and its treatment.
著者: Thomas DR, Cote TR, Lawhorne L, Levenson SA, Rubenstein LZ, Smith DA, Stefanacci RG, Tangalos EG, Morley JE; Dehydration Council.
雑誌名: J Am Med Dir Assoc. 2008 Jun;9(5):292-301. doi: 10.1016/j.jamda.2008.03.006.
Abstract/Text: Dehydration in clinical practice, as opposed to a physiological definition, refers to the loss of body water, with or without salt, at a rate greater than the body can replace it. We argue that the clinical definition for dehydration, ie, loss of total body water, addresses the medical needs of the patient most effectively. There are 2 types of dehydration, namely water loss dehydration (hyperosmolar, due either to increased sodium or glucose) and salt and water loss dehydration (hyponatremia). The diagnosis requires an appraisal of the patient and laboratory testing, clinical assessment, and knowledge of the patient's history. Long-term care facilities are reluctant to have practitioners make a diagnosis, in part because dehydration is a sentinel event thought to reflect poor care. Facilities should have an interdisciplinary educational focus on the prevention of dehydration in view of the poor outcomes associated with its development. We also argue that dehydration is rarely due to neglect from formal or informal caregivers, but rather results from a combination of physiological and disease processes. With the availability of recombinant hyaluronidase, subcutaneous infusion of fluids (hypodermoclysis) provides a better opportunity to treat mild to moderate dehydration in the nursing home and at home.
J Am Med Dir Assoc. 2008 Jun;9(5):292-301. doi: 10.1016/j.jamda.2008.0...

急性出血以外の体液欠乏における身体所見

口腔粘膜の乾燥は感度がよいが、口呼吸をしている患者や飲水や食事の直後には信頼できる指標にはならない。
単独の所見ではなく、複数の身体所見を組み合わせて体液欠乏を判定する。
出典
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1: The rational clinical examination. Is this patient hypovolemic?
著者: McGee S, Abernethy WB 3rd, Simel DL.
雑誌名: JAMA. 1999 Mar 17;281(11):1022-9. doi: 10.1001/jama.281.11.1022.
Abstract/Text: OBJECTIVE: To review, systematically, the physical diagnosis of hypovolemia in adults.
METHODS: We searched MEDLINE (January 1966-November 1997), personal files, and bibliographies of textbooks on physical diagnosis and identified 10 studies investigating postural vital signs or the capillary refill time of healthy volunteers, some of whom underwent phlebotomy of up to 1150 mL of blood, and 4 studies of patients presenting to emergency departments with suspected hypovolemia, usually due to vomiting, diarrhea, or decreased oral intake.
RESULTS: When clinicians evaluate adults with suspected blood loss, the most helpful physical findings are either severe postural dizziness (preventing measurement of upright vital signs) or a postural pulse increment of 30 beats/min or more. The presence of either finding has a sensitivity for moderate blood loss of only 22% (95% confidence interval [CI], 6%-48%) but a much greater sensitivity for large blood loss of 97% (95% CI, 91%-100%); the corresponding specificity is 98% (95% CI, 97%-99%). Supine hypotension and tachycardia are frequently absent, even after up to 1150 mL of blood loss (sensitivity, 33%; 95% CI, 21%-47%, for supine hypotension). The finding of mild postural dizziness has no proven value. In patients with vomiting, diarrhea, or decreased oral intake, the presence of a dry axilla supports the diagnosis of hypovolemia (positive likelihood ratio, 2.8; 95% CI, 1.4-5.4), and moist mucous membranes and a tongue without furrows argue against it (negative likelihood ratio, 0.3; 95% CI, 0.1-0.6 for both findings). In adults, the capillary refill time and poor skin turgor have no proven diagnostic value.
CONCLUSIONS: A large postural pulse change (> or =30 beats/min) or severe postural dizziness is required to clinically diagnose hypovolemia due to blood loss, although these findings are often absent after moderate amounts of blood loss. In patients with vomiting, diarrhea, or decreased oral intake, few findings have proven utility, and clinicians should measure serum electrolytes, serum blood urea nitrogen, and creatinine levels when diagnostic certainty is required.
JAMA. 1999 Mar 17;281(11):1022-9. doi: 10.1001/jama.281.11.1022.

急性出血による体液量減少における身体所見

健常人では500 mL 程度の失血でも収縮期血圧の低下や臥位での頻脈が見られることは少ない。立位への体位変換による脈拍増加やめまいは感度がよいため、可能な限り評価をすることが推奨される。
出典
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1: Defining the positive tilt test: a study of healthy adults with moderate acute blood loss.
著者: Witting MD, Wears RL, Li S.
雑誌名: Ann Emerg Med. 1994 Jun;23(6):1320-3. doi: 10.1016/s0196-0644(94)70358-2.
Abstract/Text: STUDY OBJECTIVES: To define a set of orthostatic vital signs that minimize the frequency of false-positives among healthy individuals while maximizing sensitivity in detecting acute moderate blood loss and to determine the sensitivity and specificity of this optimized tilt test in detecting acute moderate blood loss.
DESIGN AND INTERVENTION: Postural vital signs were recorded in a standardized manner before and after 450-mL phlebotomy. Paired comparisons were done for a variety of criteria for a positive tilt test using receiver-operating characteristic curves.
SETTING AND TYPE OF PARTICIPANTS: Three hundred forty-five healthy euvolemic adult volunteer blood donors were tested at three community blood donation centers over a one-year period. Subjects were prospectively divided into group 1 (less than age 65; 301) and group 2 (age 65 or older; 44).
MEASUREMENTS AND MAIN RESULTS: For each combination of pulse and blood pressure in group 1, a change in pulse alone had the same or higher sensitivity with at least the same specificity. Pulse alone was similarly superior in group 2 compared with previously published combinations of pulse and blood pressure. Even the optimized tilt test had limited sensitivity in detecting acute moderate blood loss with high specificity.
CONCLUSION: In applying the tilt test to young adults without cardiovascular disease, pulse measurement usually is all that is necessary.
Ann Emerg Med. 1994 Jun;23(6):1320-3. doi: 10.1016/s0196-0644(94)70358...

尿検査による体液欠乏の評価-FENaとFEUN

腎前性腎不全を評価するときにFENa、FEUNといった指標が有用である。FEUNは利尿薬を使用している場合にも信頼性が高い。
出典
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1: Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure.
著者: Carvounis CP, Nisar S, Guro-Razuman S.
雑誌名: Kidney Int. 2002 Dec;62(6):2223-9. doi: 10.1046/j.1523-1755.2002.00683.x.
Abstract/Text: BACKGROUND: Fractional excretion of sodium (FENa) has been used in the diagnosis of acute renal failure (ARF) to distinguish between the two main causes of ARF, prerenal state and acute tubular necrosis (ATN). However, many patients with prerenal disorders receive diuretics, which decrease sodium reabsorption and thus increase FENa. In contrast, the fractional excretion of urea nitrogen (FEUN) is primarily dependent on passive forces and is therefore less influenced by diuretic therapy.
METHODS: To test the hypothesis that FEUN might be more useful in evaluating ARF, we prospectively compared FEUN with FENa during 102 episodes of ARF due to either prerenal azotemia or ATN.
RESULTS: Patients were divided into three groups: those with prerenal azotemia (N = 50), those with prerenal azotemia treated with diuretics (N = 27), and those with ATN (N = 25). FENa was low only in the patients with untreated plain prerenal azotemia while it was high in both the prerenal with diuretics and the ATN groups. FEUN was essentially identical in the two pre-renal groups (27.9 +/- 2.4% vs. 24.5 +/- 2.3%), and very different from the FEUN found in ATN (58.6 +/- 3.6%, P < 0.0001). While 92% of the patients with prerenal azotemia had a FENa <1%, only 48% of those patients with prerenal and diuretic therapy had such a low FENa. By contrast 89% of this latter group had a FEUN <35%.
CONCLUSIONS: Low FEUN (
Kidney Int. 2002 Dec;62(6):2223-9. doi: 10.1046/j.1523-1755.2002.00683...

FENaが低値となりうる病態

FENaは尿細管でのNaの再吸収能を見る指標であり、腎血流が低下する病態や腎血管の攣縮が生じる病態でも低値を示す。
出典
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1: Finding the cause of acute kidney injury: which index of fractional excretion is better?
著者: Gotfried J, Wiesen J, Raina R, Nally JV Jr.
雑誌名: Cleve Clin J Med. 2012 Feb;79(2):121-6. doi: 10.3949/ccjm.79a.11030.
Abstract/Text: The fractional excretion of urea (FEU) is a useful index for differentiating the main categories of causes of acute kidney injury, ie, prerenal causes and intrinsic causes. It may be used in preference to the more widely used fractional excretion of sodium (FENa) in situations in which the validity of the latter is limited, such as in patients taking a diuretic.
Cleve Clin J Med. 2012 Feb;79(2):121-6. doi: 10.3949/ccjm.79a.11030.

内頸静脈からのCVP推定

胸骨角からの静脈圧の高さ
胸骨角は右房より5 cm高い位置にあり、これは坐位~臥位となっても変わらない。このため、推定CVP(cmH2O)は「内頸静脈の拍動点と胸骨角の高さの差+5 cm」となる。
視診では外頸静脈は内頸静脈より観察しやすい。視診で外頸静脈を評価し、虚脱する(呼吸性変動が観察できる)部位を同定する。胸骨角の高さを中心静脈圧5 cmH2Oとして、虚脱する高さと比較する。
出典
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1: Noninvasive evaluation of right atrial pressure.
著者: Beigel R, Cercek B, Luo H, Siegel RJ.
雑誌名: J Am Soc Echocardiogr. 2013 Sep;26(9):1033-42. doi: 10.1016/j.echo.2013.06.004. Epub 2013 Jul 13.
Abstract/Text: In current practice, right atrial pressure (RAP) is an essential component in the hemodynamic assessment of patients and a requisite for the noninvasive estimation of the pulmonary artery pressures. RAP provides an estimation of intravascular volume, which is a critical component for optimal patient care and management. Increased RAP is associated with adverse outcomes and is independently related to all-cause mortality in patients with cardiovascular disease. Although the gold standard for RAP evaluation is invasive monitoring, various techniques are available for the noninvasive evaluation of RAP. Various echocardiographic methods have been suggested for the evaluation of RAP, consisting of indices obtained from the inferior vena cava, systemic and hepatic veins, tissue Doppler parameters, and right atrial dimensions. Because the noninvasive evaluation of RAP involves indirect measurements, multiple factors must be taken into account to provide the most accurate estimate of RAP. The authors review the data supporting current guidelines, identifying areas of agreement, conflict, limitation, and uncertainty.

Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.
J Am Soc Echocardiogr. 2013 Sep;26(9):1033-42. doi: 10.1016/j.echo.201...

胸骨角と右房の位置関係

体の傾斜角度にかかわらず、右房の5 cm高い位置に胸骨角がある。これを利用して、診察や超音波検査で内頸静脈の拍動点が観察できる高さと胸骨角を比較し、中心静脈圧を推定することができる(胸骨角レベルで拍動点を観察=推定中心静脈圧5 cmH2Oと判定)。
出典
img
1: 編集部にて作図

高齢者の体液分布

脂肪には水分が少なく、筋肉には多く含まれる。そのため、筋量の少ない高齢者、女性は体内水分比率が小さく、体液欠乏に弱い。
出典
imgimg
1: Prevalence, risk factors and strategies to prevent dehydration in older adults.
著者: Wotton K, Crannitch K, Munt R.
雑誌名: Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.
Abstract/Text: The treatment of dehydration in older adults admitted from residential care to an acute hospital setting may lead to haemodynamic stability. There is however an increased risk for short or long term alterations in physiological, cognitive and psychological status and ultimately, decreased quality of life. Such acute care admissions could be decreased where preventative strategies tailored to address individual risk factors are combined with more frequent assessment of the degree of hydration. The questionable reliability of assessment criteria in older adults increases the need to use multiple signs and symptoms in the identification and differentiation of early and late stages of dehydration. This article reviews various risk factors, explores the reliability of clinical signs and symptoms and reinforces the need to use multiple patient assessment cues if nurses are to differentiate between, and accurately respond to, the various causes of dehydration. Specific strategies to maintain hydration in older adults are also identified.
Contemp Nurse. 2008 Dec;31(1):44-56. doi: 10.5172/conu.673.31.1.44.