ORIGINAL CONTRIBUTION orthostatic vital signs
Orthostatic Vital Signs in Emergency Department Patients Study objective: To examine the variability and define the normal ranges of orthostatic vital signs in an emergency department population. Design: Descriptive. Setting: The ED of an urban teaching hospital in Denver, Colorado. Type of participants: Adult ED patients with no history of recent blood or fluid losses. Measurements: Lying and standing heart rate and blood pressure measured by an automated instrument. Results: In 132 presumed euvolemic patients, the statistical normal ranges (mean +_ 2 SD). of orthostatic vital signs were wide: on standing, the heart rate range was from ~ 5.0 to ~ 39.4 beats per minute; for systolic blood pressure, the range was ~ 20 to ~ 25.7 m m Hg; and for diastolic blood pressure, the range was $ 6.4 to ~ 24.9 m m Hg. Ih this sample, 43% had "positive" orthostatic vital signs according to currently accepted values. Conclusion: The data from this study indicate that there is a wider than expected variation in orthostatic vital signs among presumed euvoIemic ED patients. [Koziol-McLain J, Lowenstein SR, Fuller B: Orthostatic vital signs in emergency department patients. Ann Emerg Med June 1991;20:606-610.] INTRODUCTION Orthostatic (postural) heart rate and blood pressure measurements are frequently used as indicators of intravascular volume status in the emergency setting.l-3 Clinical decisions are often reached based on the magnitude of the orthostatic response. IV fluid administration, continued patient observation, and further testing are routine interventions initiated in the emergency setting for persons with positive orthostatic changes. Orthostatic heart rate and blood pressure measurements are the standard of emergency medical and nursing care for persons with known or suspected blood or fluid loss (eg, vomiting, diarrhea, or intra-abdominal hemorrhage). They are also indicated in the evaluation of syncope, dizziness, and weakness. 4-7 Finally, in the initial evaluation of patients with metabolic abnormalities (including azotemia, hyponatremia, metabolic alkalosis, and diabetic ketoacidosis), orthostatic vital sign measurements are considered essential. 8-12 Lying and standing vital sign measurements are given great importance in clinical practice. Surprisingly, few studies exist that validate their merit. We therefore conducted this study to examine the variations in orthostatic vital signs in an emergency department population. Our study addressed two questions. What is the range of normal of orthostatic vital signs in a sample of ED patients who have no recent fluid or blood losses? And what variables (eg, age, medications, fever) are associated with more marked orthostatic vital signs in euvolemic ED patients?
Jane KozioI-McLain, RN, MS*t Steven R Lowenstein, MD, MPH*t Barbara Fuller, RN, PhD:~ Denver, Colorado From the Emergency Medicine Research Center* and the Schools of Medicinet and Nursing,t University of Colorado Health Sciences Center, Denver. Received for publication November 21, 1989. Revisions received June 11, and November 21, 1990. Accepted for publication December 14, 1990. Presented at the Emergency Nurses Association Scientific Assembly in Washington, DC, September 1989. Address for reprints: Jane KozioI-McLain, RN, University of Colorado Health Sciences Center, 4200 E Ninth Avenue, Box B-215, Denver, Colorado 80262.
MATERIALS A N D METHODS We measured lying and standing vital signs in a convenience sample of adult patients visiting the ED of an urban teaching hospital. Patients were entered during a four-week period in the spring of 1989. Data were collected between the hours of 7:00 AM and 8:00 PM during shifts when one of
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ORTHOSTATIC VITAL SIGNS KozioI-McLain, Lowenstein & Fuller
the a u t h o r s w a s a v a i l a b l e . D u r i n g those shifts, all eligible patients were entered into the study. Approval from the i n s t i t u t i o n a l review board was obtained, and e a c h subject gave w r i t t e n , i n f o r m e d consent. P a t i e n t s were i n c l u d e d in t h e study only if s t a n d i n g was feasible and safe. Patients were excluded if IV therapy was i n i t i a t e d in the prehospital setting, the p a t i e n t required resusc i t a t i o n for c h e s t or a b d o m i n a l trauma, i m m e d i a t e m e d i c a l r e s u s citation was d e e m e d n e c e s s a r y (eg, ischemic chest pain, respiratory distress), baseline s y s t o l i c b l o o d pres ~ sure was less t h a n 90 m m Hg, cervical-spine immobilization was in place, or the p a t i e n t exhibited combative b e h a v i o r or a l t e r e d m e n t a l status. Data were c o l l e c t e d i m m e d i a t e l y after arrival in the ED and before any interventions. A short, structured questionnaire was a d m i n i s t e r e d verbally to o b t a i n i n f o r m a t i o n a b o u t age, sex, chief c o m p l a i n t , and fluid loss history. Patients were excluded if they r e p o r t e d v o m i t i n g , m e n o r rhagia, diarrhea, or absent oral fluid intake in the p r e v i o u s 24 hours. In addition, i n f o r m a t i o n was o b t a i n e d regarding c u r r e n t m e d i c a t i o n a n d medical problems (eg, diabetes, heart disease). Orthostatic v i t a l signs were m e a sured using an a u t o m a t e d i n s t r u m e n t (model 1846, D i n a m a p ® M o n i t o r , Critikon, Tampa, Florida) w i t h an attached printer to m i n i m i z e measurement error and v a r i a b i l i t y . C l i n i c a l trials have been carried out to determine the m e a n difference b e t w e e n the measurements of central arterial pressure and pressure m e a s u r e m e n t s obtained by the D i n a m a p ® Monitor. Mean differences r e p o r t e d b y Critikon for systolic b l o o d pressure, diastolic blood pressure,, and heart rate were 2.80 m m Hg (SD, 5.2 m m Hg), 2.91 m m Hg (SD, 4.79 m m Hg), and - 1 . 1 7 (SD, 2.68), r e s p e c t i v e l y . 13 These mean differences are n o t clinically significant and are within American Association of Medical Instrumentation guidelines. A blood pressure cuff was chosen for each patient based on arm circumference. Baseline heart rate and blood pressure measurements were taken after the patient had been in t h e s u p i n e position for at 1.east t h r e e m i n u t e s . Two m i n u t e s after a change to the standing p o s i t i o n , h e a r t r a t e a n d 20:6:June1991
TABLE 1. Normal range of orthostatic vital signs in presumed euvolemic patients
Mean (SD) Heart rate Systolic blood pressure (ram Hg) Diastolic blood pressure (rnm Hg)
1" 17.2 (11.1) 1' 2.8 (11.4) 1" 9.2 (7.8)
Statistically Normal Range* (132 Patients) ,J, 5 ,j, 20 $ 6.4 -
1' 39.4 1' 25.7 1' 24.9
*Mean +- 2 SD,
blood p r e s s u r e m e a s u r e m e n t s were repeated. 14q60rthostatic change scores were d e t e r m i n e d for each vital sign by subtracting the supine from the standing m e a s u r e m e n t . O r t h o s t a t i c v i t a l signs w e r e cons i d e r e d " p o s i t i v e " if h e a r t r a t e increased m o r e t h a n 20 beats per minu t e or systolic or diastolic blood pressure decreased by m o r e t h a n 10 m m Hg, as s u g g e s t e d in s o m e m e d i c a l and nursing textbooks (although reco m m e n d a t i o n s are generally n o t referenced)JT-19 D a t a were a n a l y z e d at the Emergency Medicine Research Center, U n i v e r s i t y of C o l o r a d o H e a l t h Scie n c e s C e n t e r , D e n v e r , u s i n g SAS (SAS Institute, Cary, N o r t h Carolina). Values for c o n t i n u o u s variables are expressed as the m e a n _+ SD. T h e o r t h o s t a t i c v i t a l signs of pat i e n t s w i t h n o h i s t o r y of f l u i d or blood loss in the preceding 24 hours were subjected to univariate analysis. T h e " n o r m a l v a r i a t i o n " of o r t h o static vital signs in this group of presumed euvolemic adults presenting to the ED were identified by examining the statistical normal range (mean -+ twice the SD, to include app r o x i m a t e l y 95% of t h e h e a l t h y sample). 2° Numerous variables were exami n e d for t h e i r p o s s i b l e a s s o c i a t i o n w i t h o r t h o s t a t i c v i t a l signs a m o n g t h o s e p r e s u m e d e u v o l e m i c subjects. Student's t test was used to compare m e a n o r t h o s t a t i c vital signs according to sex. To compare m e a n orthostatic vital signs according to recent alcohol ingestion and pregnancy, where s a m p l e sizes were small, the W i l c o x o n r a n k - s u m t e s t w a s used. Pearson's correlation coefficient was used to test for an association a m o n g orthostatic vital signs and age, temperature, and baseline vital sign measurements. To d e t e r m i n e if t e m p o r a l variations exist, we c o m p a r e d m e a n o r t h o s t a t i c c h a n g e scores in t h r e e t i m e groups (eg, 7:00 AM t o 11:00 AM, 11:00 AM tO 4 : 0 0 PM, and 4:00 P/V[ tO Annals of Emergency Medicine
8:00 PM) using o n e - w a y a n a l y s i s of variance (ANOVA).
RESULTS One hundred thirty-two patients denied recent fluid or blood loss and were p r e s u m e d " e u v o l e m i c . " T h e r e was no attrition; clinical i n f o r m a t i o n and o r t h o s t a t i c v i t a l signs were obtained from all patients in the sample. In general, the sample was young ( m e a n age, 34.1 -+ 13.6 years; age r a n g e , 18 to 80 y e a r s ) a n d f e m a l e (61%). For comparison, during a onew e e k period in the spring of 1989, the t o t a l ED p o p u l a t i o n w a s s i m i l a r l y young (805 patients; m e a n age, 32.5 -+ 17.0 years) and f e m a l e (58.3%). Most study patients were afebrile (mean, 37.1 _+ 0.6 C; 98th percentile, 38.0 C). The m o s t c o m m o n presenting c o m p l a i n t s were u p p e r respirat o r y s y m p t o m s (20%), a b d o m i n a l pain (16%), pain other than abdominal (14%), and m i n o r musculoskeletal injuries (11%). As s h o w n (Table 1), the average euv o l e m i c patient in the ED had an ort h o s t a t i c h e a r t rate change score of an increase of 17.2 beats per m i n u t e (SD, 11.1), w h i c h is very close to 20 beats per minute, the textbook upper l i m i t of normal. The statistical norm a l range - f r o m a d e c r e a s e of 5 beats per m i n u t e to an increase of 39.4 beats per m i n u t e - was wide. T h e average o r t h o s t a t i c s y s t o l i c blood pressure change score was an increase of 2.8 +- 11.4 m m Hg. Again, the statistical n o r m a l range for orthostatic systolic blood pressure was wide - from a decrease of 20 m m Hg to an increase of 25.7 m m Hg. Finally, the average orthostatic dia s t o l i c blood pressure change score was an increase of 9.2 + 7.8 m m Hg. T h e s t a t i s t i c a l n o r m a l range for orthostatic diastolic blood pressure, although wide - a decrease of 6.4 m m Hg and an increase of 24.9 m m Hg did not include the t e x t b o o k l i m i t of n o r m a l (a decrease of 10 m m Hg). F o r t y - t h r e e p e r c e n t of the s a m p l e 607/29
ORTHOSTATIC KozioI-McLain,
VITAL S I G N S L o w e n s t e i n & Fuller
FIGURE. S c a t t e r p l o t of o r t h o s t a t i c heart rate and age among euvolemic ED patients. Q, M a y represent duplicate observations; 18 observations are hidden.
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00
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Age (yr)
TABLE 2. Mean +_ SD orthostatic vital sign change scores No. of Patients
Heart Rate
Schneider 36 (1922)
2,000
1" 17.9 ± 2.0
I" 2.3 ± NR
$ 8.1 ± NR
Currens 3z (1948)
1,000
1' 13.3 ± NR
NR*
NRt
200
1` 17.2 _+ 11.1
1` 2.8 + 11.4
1` 9.2 ± 7.8
56 40
1` 16.5 + 8.2 1" 9.9 + 1.3
1` 1.0 + 7.0 1` 7.3 + 1.8
I" 6.0 -+ 3.0 ,l, 0.9 ~- 1.1
50
1` 12.6 ± 11.7
$ 12.2 4__ 7.4
3.8 -+ 6.1
Present study Start2~ (1943) Schulte TM (1986)~ Iwerson-Moore and Newion m (1986)
Systolic Blood Pressure
Diastolic Blood Pressure
NR, not reported. *Systolic blood pressure $ 10 mm Hg or more in 32.8% of patients. tDiastol;c blood pressure $ 4 mm Hg or more in 12.0% of palienls ~Results of patients who had orthostatic vital signs measured two minutes after position change.
had "positive" orthostatic vital signs a c c o r d i n g .to c u r r e n t l y a c c e p t e d values. N u m e r o u s biologic and historical parameters were tested for their relationship to orthostatic vital signs. Sex (61% female), pregnancy (11), recent alcohol ingestion (six), temperature (4% had temperatures of more than 38.0 C), and temporal variation were not associated with orthostatic vital sign change scores in this group of euvolemic ED patients (although the numbers for comparison were small). Orthostatic systolic blood pressure was not significantly related to any of the independent variables. However, several s t u d y variables were found to be significantly associated w i t h o r t h o s t a t i c heart rate and diastolic blood pressure. There was a negative, relatively strong, and statistically s i g n i f i c a n t c o r r e l a t i o n between age and orthostatic heart rate change (r = - 0 . 3 6 ; P < .001); pa30~608
tients who were older tended to have lower orthostatic heart rate change scores (Figure). Baseline heart rate and orthostatic heart rate showed a w e a k n e g a t i v e c o r r e l a t i o n (r = - 0 . 1 8 ; P < .05). Baseline diastolic blood pressure and o r t h o s t a t i c diastolic blood pressure were also negatively correlated (r = - 0 . 2 7 ; P = .00%
The s y m p t o m s of thirst and dizzin e s s w e r e also e x a m i n e d . W h e n asked if thirsty, a majority of the patients (51%) responded in the affirmative. There were no significant differences in orthostatic vital signs b e t w e e n those w h o c o m p l a i n e d of thirst and those who did not. The patients were also asked if they had felt dizzy on standing; 26% stated they had e x p e r i e n c e d dizziness. T h e r e were no statistically significant differences for orthostatic heart rate and systolic blood pressure between those who were dizzy and those who Annals of Emergency Medicine
were not. Mean orthostatic diastolic blood pressure, however, was different in those with dizziness (mean, 1' 6.32 m m Hg) than in those w h o were not (mean, 1' 10.27 m m Hg; P = .03). Although statistically significant, this difference is not clinically important. Recent exercise, edema, and ascites occurred rarely in the sample (one, none, and none, respectively). In addition, a history of selected disease processes (eg, diabetes, renal insufficiency) and specified medications (eg, d i u r e t i c s , [3-adrenergic b l o c k i n g agents) were not frequent enough in the s a m p l e to d r a w c o n c l u s i o n s a b o u t their r e l a t i o n s h i p to o r t h o static vital signs.
DISCUSSION " W e suspect that inability to regulate the circulation in the upright position is one reason w h y persons take to their beds when they are sick." I Starr, 1943 al The physiologic response to standing is a f i n e l y t u n e d h o m e o s t a t i c m e c h a n i s m in h u m a n beings. On assuming the erect position, the bar•receptor reflex causes an immediate, p o w e r f u l s y m p a t h e t i c r e s p o n s e to maintain cardiac output and cerebral perfusion. Decreased pressure on the bar•receptors causes decreased stimulation of the vasomotor center and results in two responses: 1) excitation of the v a s o c o n s t r i c t o r center, causing peripheral vasoconstriction as evidenced by increased blood pressure [~-adrenergic effect), and 2) inhibition of the vagal center, causing increased heart rate and strength of c o n t r a c t i o n (f~-adrenergic effect). 22 Orthostatic vital signs are an object i v e m e a s u r e m e n t of h u m a n response to standing. Variation in orthostatic vital signs can be attributed to n u m e r o u s factors, including normal biologic variations among people as well as disr u p t i o n of t h e m e c h a n i s m itself. Dysfunction anywhere in the bar•receptor feedback loop, medication and disease processes, and dysfunction of the muscle p u m p mechanism will all 20:6 June 1991
OR]-HOSTATIC VITAL SIGNS KozioI-McLain, Lowenstein & Fuller
theoretically alter the orthostatic response.Z3, 24 In addition, previous studies have identified an association among age, fever, and recent alcohol ingestion and baseline and orthostatic vital sign measurements.14, 25-3o Abnormal orthostatic responses are generally categorized as functional or neurogenic. 31-33 In normal healthy persons with a normal fluid volume, standing affects blood pressure and heart rate minimally and generally goes u n n o t i c e d , z3 When a fluid-depleted person stands up, however, the s y m p a t h e t i c response is exaggerated. The magnitude of the orthostatic heart rate and blood pressure response is suspected to be associated with the amount of fluid depletion and a marker of early (mild) shock.Z, 34 Orthostatic vital sign measurements are currently used in clinical practice to equate intravascular volume status. However, the n o r m a l ranges are not well defined. Three centuries ago, Sir John Floyer, Knight of Lichfield, stressed in his Physician's Pulse-Watch the need to establish normal values for the pulse rate by age, sex, and condition so that "we may know the natural pulse, and the excesses and defects from this in diseases. ''35 Indeed, it is essential to know the range of normal values for all of the orthostatic vital signs if change scores are to be used to define disease. This study examined orthostatic vital signs in 132 ED patients. A wide variation in orthostatic vital signs was found despite the homogenous characteristics of the sample. Furthermore, the variables age, sex, baseline vital signs, and volume loss history only explained a small fraction of the variation. Although diurnal variation may exist, our study showed n o temporal, variation in patients between 7:00 AM and 8:00 PM. This study, however, can be generalized only to similar samples. The study sample was nontachycardiac (96% had a resting heart rate of less than 100 m m Hg) and nonhypotensive (95% had a baseline systolic blood pressure of more than 104 m m Hg, and 95% had a diastolic blood pressure of more than 58 m m Hg). We specifically excluded patients who had obvious v o l u m e loss by study design (eg, history of blood or fluid loss, baseline systolic blood pressure of less than 90 m m Hg, 20:6:June1991
trauma resuscitation). Despite these limitations, our results are similar to those of previous studies. The normal ranges of orthostatic vital signs identified in our study and five other studies are listed (Table 2). 14,15,21,36,37 The subjects in all five of these studies were healthy adults, with the exception of our study, and the erect position was achieved by active standing (rather than a passive posture change by a tilt table). In the l a r g e s t study, Schneider studied orthostatic vital signs in 2,000 healthy young aviators. 36 The mean orthostatic heart rate, systolic blood pressure, and diastolic blood pressure change scores in his study were almost identical to those in our study. The wide variations of orthostatic change scores in healthy persons suggest that large biological differences exist among individuals. The relationship between orthostatic vital signs and volume status has not been supported by rigorous testing. In 1980, Knopp et al studied orthostatic vital signs in 100 healthy volunteers before and after phlebotomy. 38 T h e s u b j e c t s were phlebotomized either 450 or 1,000 mL. There were no differences in orthostatic vital signs between no blood loss and 450-mL blood loss or between 450-mL blood loss and 1,000mL blood loss. The researchers were only able to distinguish between a blood loss of 1,000 mL and no blood loss using an orthostatic heart rate change score of 30 beats per minute or more. In a preliminary report, Levitt et al measured orthostatic vital signs in patients presenting to an ED with "complaints suggestive of dehydration and/or blood loss. ''39 For their sample of 202 patients, they constructed a forward, stepwise, linear regression model for dehydration percentage (calculated using measured serum osmolality and body weight). They found a statistically significant association between dehydration percentage and the variables of orthostatic heart rate (P = .0165) and age (P = .0047). However, they noted that the amount of variation in dehyd r a t i o n p e r c e n t a g e e x p l a i n e d by orthostatic heart rate and age was not clinically useful. Our study confirmed for ED patients what has been suggested previously for healthy volunteers - that Annals of Emergency Medicine
the biologic variability in orthostatic vital signs a m o n g i n d i v i d u a l s is great. In future studies, examination of orthostatic diastolic blood pressure should receive priority attention, being the most reliable of the orthostatic vital signs. O r t h o s t a t i c diastolic blood pressure was characterized by the least variability and smallest SD in our study. The reliability of the diastolic blood pressure over o t h e r o r t h o s t a t i c vital signs, demonstrated in this study, is consistent with what is reported in the literature. 4° Further research may help to clarify the usefulness of orthostatic vital signs in the ED setting. First, further research is needed to identify more reliable and valid screening tools, such as serum osmolality or urinespecific gravity, for identifying the volume-deficient ED patient. Second, factors that might contribute to the variation in orthostatic vital signs in ED patients, such as autonomic dysfunction, pain, fright, or concomitant medical conditions, should be studied. CONCLUSION There is a w i d e r - t h a n - e x p e c t e d variation in orthostatic vital signs, presumably among euvolemic ED patients. Many normal patients may have what we have considered in the past to be orthostatic vital signs syno n y m o u s w i t h h y p o v o l e m i a . Although orthostatic vital signs might differentiate the ED patient with a massive volume deficit, in this group of patients it would be unsafe and unnecessary to insist on the standing position.
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35. Ployer J: The Physician's Puls&Watch; or an Essay to Explain the Old Art of Feeling the Pulse, and to Improve it by the Help of a Pulse Watch. London, Prince's Arms in St Paul's Church-Yard, 1707.
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25. Johnson JM, Niederberger M, Robell LV, et ah Com~ petition between cutaneous vasodilator and vasoconstrictor reflexes in man. [ AppI Physiol i973;35: 798-803.
8. Shapiro JI, Schrier RW: Renal diseases, fluid and electrolyte disorders , and hypertension, in Schrier RW (ed): Medicine Diagnosis and Treatment. Boston, Little, Brown and Co, 1988, p 131. 9. Hofeldt FD, Ridgway EC: Metabolism and endocrinology~ in Schrier RW (ed): Medicine Diagnosis and Treatment. Boston, Little, Brown and Co, 1988, p 347. 10. Gabow PA, Peterson LN: Disorders of potassium metabolism, in 8chrier RW ted}: Renal and Electrolyte Disorders, ed 2. Boston, Little, Brown and Co, 1980, p 183.
14. Schulte D: A comparison of time intervals after posture change when measuring pulse and blood pressure in healthy elderly and nouelderly subjects. Master's thesis~ University of Colorado, Denver, 1986. 18. Iwerson-Moore K, N e w t o n K: Orthostatic heart rates and blood pressures in healthy young women and men. Heart Lung 1986;15:611-617. 16. Kennedy GT, Crawford MH: Optimal position and timing of blood pressure and heart rate measurements to detect orthostatic changes in patients with ischemic heart disease. [ Card Rehab 1984;4:219-223. 17. Milligan Metheny N, Snively WD: Nurse's Handbook of Fluid Balance, ed 4. Philadelphia, JB Lippincott, 1983. 18. Kroenke K: Orthostatie hypotension. West J Med
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26. Lind AR, Leithead CS, McNicol GW: Cardiovascular changes during syncope induced by tilting men in heat. J AppI Physiol 1968;25:268-276.
37. Currens JH: A comparison of the blood pressure in the lying and standing positions: A study of five hundred m e n and five h u n d r e d w o m e n . A m Heart J 1948;35:646-654.
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38. Knopp R, Claypool R~ Leonardi D: Use of the tilt test in measuring acute blood loss. A n n Emerg Med 1980;9:72-75.
28. Tomaszewski CA, Cline DM, Whitley TW: Effects of acute ethanol ingestion on orthostatic vital signs (abstract). Ann Emerg Med 1989;18:438.
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29. Fuchs SM, Jaffe DM: Evaluation of the "tilt test" in children. Ann Emerg Med 1987;16:386-390. 30. Bergman GE, Reisner FF, Anwar iV.A: Orthostatic changes in normovolemic children: An analysis of the
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40. Mannix FL: Hemorrhagic shock, in Rosen P, Baker FJ II, Barkin RM leds]: Emergency Medicine: Concepts and Clinical Practice, ed 2. St Louis, CV Mosby, 1988, p 179-187.
20:6 June 1991
Orthostatic Vital Signs in Emergency Department Patients Study objective: To examine the variability and define the normal ranges of orthostatic vital signs in an emergency department population. Design: Descriptive. Setting: The ED of an urban teaching hospital in Denver, Colorado. Type of participants: Adult ED patients with no history of recent blood or fluid losses. Measurements: Lying and standing heart rate and blood pressure measured by an automated instrument. Results: In 132 presumed euvolemic patients, the statistical normal ranges (mean +_ 2 SD). of orthostatic vital signs were wide: on standing, the heart rate range was from ~ 5.0 to ~ 39.4 beats per minute; for systolic blood pressure, the range was ~ 20 to ~ 25.7 m m Hg; and for diastolic blood pressure, the range was $ 6.4 to ~ 24.9 m m Hg. Ih this sample, 43% had "positive" orthostatic vital signs according to currently accepted values. Conclusion: The data from this study indicate that there is a wider than expected variation in orthostatic vital signs among presumed euvoIemic ED patients. [Koziol-McLain J, Lowenstein SR, Fuller B: Orthostatic vital signs in emergency department patients. Ann Emerg Med June 1991;20:606-610.] INTRODUCTION Orthostatic (postural) heart rate and blood pressure measurements are frequently used as indicators of intravascular volume status in the emergency setting.l-3 Clinical decisions are often reached based on the magnitude of the orthostatic response. IV fluid administration, continued patient observation, and further testing are routine interventions initiated in the emergency setting for persons with positive orthostatic changes. Orthostatic heart rate and blood pressure measurements are the standard of emergency medical and nursing care for persons with known or suspected blood or fluid loss (eg, vomiting, diarrhea, or intra-abdominal hemorrhage). They are also indicated in the evaluation of syncope, dizziness, and weakness. 4-7 Finally, in the initial evaluation of patients with metabolic abnormalities (including azotemia, hyponatremia, metabolic alkalosis, and diabetic ketoacidosis), orthostatic vital sign measurements are considered essential. 8-12 Lying and standing vital sign measurements are given great importance in clinical practice. Surprisingly, few studies exist that validate their merit. We therefore conducted this study to examine the variations in orthostatic vital signs in an emergency department population. Our study addressed two questions. What is the range of normal of orthostatic vital signs in a sample of ED patients who have no recent fluid or blood losses? And what variables (eg, age, medications, fever) are associated with more marked orthostatic vital signs in euvolemic ED patients?
Jane KozioI-McLain, RN, MS*t Steven R Lowenstein, MD, MPH*t Barbara Fuller, RN, PhD:~ Denver, Colorado From the Emergency Medicine Research Center* and the Schools of Medicinet and Nursing,t University of Colorado Health Sciences Center, Denver. Received for publication November 21, 1989. Revisions received June 11, and November 21, 1990. Accepted for publication December 14, 1990. Presented at the Emergency Nurses Association Scientific Assembly in Washington, DC, September 1989. Address for reprints: Jane KozioI-McLain, RN, University of Colorado Health Sciences Center, 4200 E Ninth Avenue, Box B-215, Denver, Colorado 80262.
MATERIALS A N D METHODS We measured lying and standing vital signs in a convenience sample of adult patients visiting the ED of an urban teaching hospital. Patients were entered during a four-week period in the spring of 1989. Data were collected between the hours of 7:00 AM and 8:00 PM during shifts when one of
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ORTHOSTATIC VITAL SIGNS KozioI-McLain, Lowenstein & Fuller
the a u t h o r s w a s a v a i l a b l e . D u r i n g those shifts, all eligible patients were entered into the study. Approval from the i n s t i t u t i o n a l review board was obtained, and e a c h subject gave w r i t t e n , i n f o r m e d consent. P a t i e n t s were i n c l u d e d in t h e study only if s t a n d i n g was feasible and safe. Patients were excluded if IV therapy was i n i t i a t e d in the prehospital setting, the p a t i e n t required resusc i t a t i o n for c h e s t or a b d o m i n a l trauma, i m m e d i a t e m e d i c a l r e s u s citation was d e e m e d n e c e s s a r y (eg, ischemic chest pain, respiratory distress), baseline s y s t o l i c b l o o d pres ~ sure was less t h a n 90 m m Hg, cervical-spine immobilization was in place, or the p a t i e n t exhibited combative b e h a v i o r or a l t e r e d m e n t a l status. Data were c o l l e c t e d i m m e d i a t e l y after arrival in the ED and before any interventions. A short, structured questionnaire was a d m i n i s t e r e d verbally to o b t a i n i n f o r m a t i o n a b o u t age, sex, chief c o m p l a i n t , and fluid loss history. Patients were excluded if they r e p o r t e d v o m i t i n g , m e n o r rhagia, diarrhea, or absent oral fluid intake in the p r e v i o u s 24 hours. In addition, i n f o r m a t i o n was o b t a i n e d regarding c u r r e n t m e d i c a t i o n a n d medical problems (eg, diabetes, heart disease). Orthostatic v i t a l signs were m e a sured using an a u t o m a t e d i n s t r u m e n t (model 1846, D i n a m a p ® M o n i t o r , Critikon, Tampa, Florida) w i t h an attached printer to m i n i m i z e measurement error and v a r i a b i l i t y . C l i n i c a l trials have been carried out to determine the m e a n difference b e t w e e n the measurements of central arterial pressure and pressure m e a s u r e m e n t s obtained by the D i n a m a p ® Monitor. Mean differences r e p o r t e d b y Critikon for systolic b l o o d pressure, diastolic blood pressure,, and heart rate were 2.80 m m Hg (SD, 5.2 m m Hg), 2.91 m m Hg (SD, 4.79 m m Hg), and - 1 . 1 7 (SD, 2.68), r e s p e c t i v e l y . 13 These mean differences are n o t clinically significant and are within American Association of Medical Instrumentation guidelines. A blood pressure cuff was chosen for each patient based on arm circumference. Baseline heart rate and blood pressure measurements were taken after the patient had been in t h e s u p i n e position for at 1.east t h r e e m i n u t e s . Two m i n u t e s after a change to the standing p o s i t i o n , h e a r t r a t e a n d 20:6:June1991
TABLE 1. Normal range of orthostatic vital signs in presumed euvolemic patients
Mean (SD) Heart rate Systolic blood pressure (ram Hg) Diastolic blood pressure (rnm Hg)
1" 17.2 (11.1) 1' 2.8 (11.4) 1" 9.2 (7.8)
Statistically Normal Range* (132 Patients) ,J, 5 ,j, 20 $ 6.4 -
1' 39.4 1' 25.7 1' 24.9
*Mean +- 2 SD,
blood p r e s s u r e m e a s u r e m e n t s were repeated. 14q60rthostatic change scores were d e t e r m i n e d for each vital sign by subtracting the supine from the standing m e a s u r e m e n t . O r t h o s t a t i c v i t a l signs w e r e cons i d e r e d " p o s i t i v e " if h e a r t r a t e increased m o r e t h a n 20 beats per minu t e or systolic or diastolic blood pressure decreased by m o r e t h a n 10 m m Hg, as s u g g e s t e d in s o m e m e d i c a l and nursing textbooks (although reco m m e n d a t i o n s are generally n o t referenced)JT-19 D a t a were a n a l y z e d at the Emergency Medicine Research Center, U n i v e r s i t y of C o l o r a d o H e a l t h Scie n c e s C e n t e r , D e n v e r , u s i n g SAS (SAS Institute, Cary, N o r t h Carolina). Values for c o n t i n u o u s variables are expressed as the m e a n _+ SD. T h e o r t h o s t a t i c v i t a l signs of pat i e n t s w i t h n o h i s t o r y of f l u i d or blood loss in the preceding 24 hours were subjected to univariate analysis. T h e " n o r m a l v a r i a t i o n " of o r t h o static vital signs in this group of presumed euvolemic adults presenting to the ED were identified by examining the statistical normal range (mean -+ twice the SD, to include app r o x i m a t e l y 95% of t h e h e a l t h y sample). 2° Numerous variables were exami n e d for t h e i r p o s s i b l e a s s o c i a t i o n w i t h o r t h o s t a t i c v i t a l signs a m o n g t h o s e p r e s u m e d e u v o l e m i c subjects. Student's t test was used to compare m e a n o r t h o s t a t i c vital signs according to sex. To compare m e a n orthostatic vital signs according to recent alcohol ingestion and pregnancy, where s a m p l e sizes were small, the W i l c o x o n r a n k - s u m t e s t w a s used. Pearson's correlation coefficient was used to test for an association a m o n g orthostatic vital signs and age, temperature, and baseline vital sign measurements. To d e t e r m i n e if t e m p o r a l variations exist, we c o m p a r e d m e a n o r t h o s t a t i c c h a n g e scores in t h r e e t i m e groups (eg, 7:00 AM t o 11:00 AM, 11:00 AM tO 4 : 0 0 PM, and 4:00 P/V[ tO Annals of Emergency Medicine
8:00 PM) using o n e - w a y a n a l y s i s of variance (ANOVA).
RESULTS One hundred thirty-two patients denied recent fluid or blood loss and were p r e s u m e d " e u v o l e m i c . " T h e r e was no attrition; clinical i n f o r m a t i o n and o r t h o s t a t i c v i t a l signs were obtained from all patients in the sample. In general, the sample was young ( m e a n age, 34.1 -+ 13.6 years; age r a n g e , 18 to 80 y e a r s ) a n d f e m a l e (61%). For comparison, during a onew e e k period in the spring of 1989, the t o t a l ED p o p u l a t i o n w a s s i m i l a r l y young (805 patients; m e a n age, 32.5 -+ 17.0 years) and f e m a l e (58.3%). Most study patients were afebrile (mean, 37.1 _+ 0.6 C; 98th percentile, 38.0 C). The m o s t c o m m o n presenting c o m p l a i n t s were u p p e r respirat o r y s y m p t o m s (20%), a b d o m i n a l pain (16%), pain other than abdominal (14%), and m i n o r musculoskeletal injuries (11%). As s h o w n (Table 1), the average euv o l e m i c patient in the ED had an ort h o s t a t i c h e a r t rate change score of an increase of 17.2 beats per m i n u t e (SD, 11.1), w h i c h is very close to 20 beats per minute, the textbook upper l i m i t of normal. The statistical norm a l range - f r o m a d e c r e a s e of 5 beats per m i n u t e to an increase of 39.4 beats per m i n u t e - was wide. T h e average o r t h o s t a t i c s y s t o l i c blood pressure change score was an increase of 2.8 +- 11.4 m m Hg. Again, the statistical n o r m a l range for orthostatic systolic blood pressure was wide - from a decrease of 20 m m Hg to an increase of 25.7 m m Hg. Finally, the average orthostatic dia s t o l i c blood pressure change score was an increase of 9.2 + 7.8 m m Hg. T h e s t a t i s t i c a l n o r m a l range for orthostatic diastolic blood pressure, although wide - a decrease of 6.4 m m Hg and an increase of 24.9 m m Hg did not include the t e x t b o o k l i m i t of n o r m a l (a decrease of 10 m m Hg). F o r t y - t h r e e p e r c e n t of the s a m p l e 607/29
ORTHOSTATIC KozioI-McLain,
VITAL S I G N S L o w e n s t e i n & Fuller
FIGURE. S c a t t e r p l o t of o r t h o s t a t i c heart rate and age among euvolemic ED patients. Q, M a y represent duplicate observations; 18 observations are hidden.
60 8
40
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00
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4'5
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72
81
Age (yr)
TABLE 2. Mean +_ SD orthostatic vital sign change scores No. of Patients
Heart Rate
Schneider 36 (1922)
2,000
1" 17.9 ± 2.0
I" 2.3 ± NR
$ 8.1 ± NR
Currens 3z (1948)
1,000
1' 13.3 ± NR
NR*
NRt
200
1` 17.2 _+ 11.1
1` 2.8 + 11.4
1` 9.2 ± 7.8
56 40
1` 16.5 + 8.2 1" 9.9 + 1.3
1` 1.0 + 7.0 1` 7.3 + 1.8
I" 6.0 -+ 3.0 ,l, 0.9 ~- 1.1
50
1` 12.6 ± 11.7
$ 12.2 4__ 7.4
3.8 -+ 6.1
Present study Start2~ (1943) Schulte TM (1986)~ Iwerson-Moore and Newion m (1986)
Systolic Blood Pressure
Diastolic Blood Pressure
NR, not reported. *Systolic blood pressure $ 10 mm Hg or more in 32.8% of patients. tDiastol;c blood pressure $ 4 mm Hg or more in 12.0% of palienls ~Results of patients who had orthostatic vital signs measured two minutes after position change.
had "positive" orthostatic vital signs a c c o r d i n g .to c u r r e n t l y a c c e p t e d values. N u m e r o u s biologic and historical parameters were tested for their relationship to orthostatic vital signs. Sex (61% female), pregnancy (11), recent alcohol ingestion (six), temperature (4% had temperatures of more than 38.0 C), and temporal variation were not associated with orthostatic vital sign change scores in this group of euvolemic ED patients (although the numbers for comparison were small). Orthostatic systolic blood pressure was not significantly related to any of the independent variables. However, several s t u d y variables were found to be significantly associated w i t h o r t h o s t a t i c heart rate and diastolic blood pressure. There was a negative, relatively strong, and statistically s i g n i f i c a n t c o r r e l a t i o n between age and orthostatic heart rate change (r = - 0 . 3 6 ; P < .001); pa30~608
tients who were older tended to have lower orthostatic heart rate change scores (Figure). Baseline heart rate and orthostatic heart rate showed a w e a k n e g a t i v e c o r r e l a t i o n (r = - 0 . 1 8 ; P < .05). Baseline diastolic blood pressure and o r t h o s t a t i c diastolic blood pressure were also negatively correlated (r = - 0 . 2 7 ; P = .00%
The s y m p t o m s of thirst and dizzin e s s w e r e also e x a m i n e d . W h e n asked if thirsty, a majority of the patients (51%) responded in the affirmative. There were no significant differences in orthostatic vital signs b e t w e e n those w h o c o m p l a i n e d of thirst and those who did not. The patients were also asked if they had felt dizzy on standing; 26% stated they had e x p e r i e n c e d dizziness. T h e r e were no statistically significant differences for orthostatic heart rate and systolic blood pressure between those who were dizzy and those who Annals of Emergency Medicine
were not. Mean orthostatic diastolic blood pressure, however, was different in those with dizziness (mean, 1' 6.32 m m Hg) than in those w h o were not (mean, 1' 10.27 m m Hg; P = .03). Although statistically significant, this difference is not clinically important. Recent exercise, edema, and ascites occurred rarely in the sample (one, none, and none, respectively). In addition, a history of selected disease processes (eg, diabetes, renal insufficiency) and specified medications (eg, d i u r e t i c s , [3-adrenergic b l o c k i n g agents) were not frequent enough in the s a m p l e to d r a w c o n c l u s i o n s a b o u t their r e l a t i o n s h i p to o r t h o static vital signs.
DISCUSSION " W e suspect that inability to regulate the circulation in the upright position is one reason w h y persons take to their beds when they are sick." I Starr, 1943 al The physiologic response to standing is a f i n e l y t u n e d h o m e o s t a t i c m e c h a n i s m in h u m a n beings. On assuming the erect position, the bar•receptor reflex causes an immediate, p o w e r f u l s y m p a t h e t i c r e s p o n s e to maintain cardiac output and cerebral perfusion. Decreased pressure on the bar•receptors causes decreased stimulation of the vasomotor center and results in two responses: 1) excitation of the v a s o c o n s t r i c t o r center, causing peripheral vasoconstriction as evidenced by increased blood pressure [~-adrenergic effect), and 2) inhibition of the vagal center, causing increased heart rate and strength of c o n t r a c t i o n (f~-adrenergic effect). 22 Orthostatic vital signs are an object i v e m e a s u r e m e n t of h u m a n response to standing. Variation in orthostatic vital signs can be attributed to n u m e r o u s factors, including normal biologic variations among people as well as disr u p t i o n of t h e m e c h a n i s m itself. Dysfunction anywhere in the bar•receptor feedback loop, medication and disease processes, and dysfunction of the muscle p u m p mechanism will all 20:6 June 1991
OR]-HOSTATIC VITAL SIGNS KozioI-McLain, Lowenstein & Fuller
theoretically alter the orthostatic response.Z3, 24 In addition, previous studies have identified an association among age, fever, and recent alcohol ingestion and baseline and orthostatic vital sign measurements.14, 25-3o Abnormal orthostatic responses are generally categorized as functional or neurogenic. 31-33 In normal healthy persons with a normal fluid volume, standing affects blood pressure and heart rate minimally and generally goes u n n o t i c e d , z3 When a fluid-depleted person stands up, however, the s y m p a t h e t i c response is exaggerated. The magnitude of the orthostatic heart rate and blood pressure response is suspected to be associated with the amount of fluid depletion and a marker of early (mild) shock.Z, 34 Orthostatic vital sign measurements are currently used in clinical practice to equate intravascular volume status. However, the n o r m a l ranges are not well defined. Three centuries ago, Sir John Floyer, Knight of Lichfield, stressed in his Physician's Pulse-Watch the need to establish normal values for the pulse rate by age, sex, and condition so that "we may know the natural pulse, and the excesses and defects from this in diseases. ''35 Indeed, it is essential to know the range of normal values for all of the orthostatic vital signs if change scores are to be used to define disease. This study examined orthostatic vital signs in 132 ED patients. A wide variation in orthostatic vital signs was found despite the homogenous characteristics of the sample. Furthermore, the variables age, sex, baseline vital signs, and volume loss history only explained a small fraction of the variation. Although diurnal variation may exist, our study showed n o temporal, variation in patients between 7:00 AM and 8:00 PM. This study, however, can be generalized only to similar samples. The study sample was nontachycardiac (96% had a resting heart rate of less than 100 m m Hg) and nonhypotensive (95% had a baseline systolic blood pressure of more than 104 m m Hg, and 95% had a diastolic blood pressure of more than 58 m m Hg). We specifically excluded patients who had obvious v o l u m e loss by study design (eg, history of blood or fluid loss, baseline systolic blood pressure of less than 90 m m Hg, 20:6:June1991
trauma resuscitation). Despite these limitations, our results are similar to those of previous studies. The normal ranges of orthostatic vital signs identified in our study and five other studies are listed (Table 2). 14,15,21,36,37 The subjects in all five of these studies were healthy adults, with the exception of our study, and the erect position was achieved by active standing (rather than a passive posture change by a tilt table). In the l a r g e s t study, Schneider studied orthostatic vital signs in 2,000 healthy young aviators. 36 The mean orthostatic heart rate, systolic blood pressure, and diastolic blood pressure change scores in his study were almost identical to those in our study. The wide variations of orthostatic change scores in healthy persons suggest that large biological differences exist among individuals. The relationship between orthostatic vital signs and volume status has not been supported by rigorous testing. In 1980, Knopp et al studied orthostatic vital signs in 100 healthy volunteers before and after phlebotomy. 38 T h e s u b j e c t s were phlebotomized either 450 or 1,000 mL. There were no differences in orthostatic vital signs between no blood loss and 450-mL blood loss or between 450-mL blood loss and 1,000mL blood loss. The researchers were only able to distinguish between a blood loss of 1,000 mL and no blood loss using an orthostatic heart rate change score of 30 beats per minute or more. In a preliminary report, Levitt et al measured orthostatic vital signs in patients presenting to an ED with "complaints suggestive of dehydration and/or blood loss. ''39 For their sample of 202 patients, they constructed a forward, stepwise, linear regression model for dehydration percentage (calculated using measured serum osmolality and body weight). They found a statistically significant association between dehydration percentage and the variables of orthostatic heart rate (P = .0165) and age (P = .0047). However, they noted that the amount of variation in dehyd r a t i o n p e r c e n t a g e e x p l a i n e d by orthostatic heart rate and age was not clinically useful. Our study confirmed for ED patients what has been suggested previously for healthy volunteers - that Annals of Emergency Medicine
the biologic variability in orthostatic vital signs a m o n g i n d i v i d u a l s is great. In future studies, examination of orthostatic diastolic blood pressure should receive priority attention, being the most reliable of the orthostatic vital signs. O r t h o s t a t i c diastolic blood pressure was characterized by the least variability and smallest SD in our study. The reliability of the diastolic blood pressure over o t h e r o r t h o s t a t i c vital signs, demonstrated in this study, is consistent with what is reported in the literature. 4° Further research may help to clarify the usefulness of orthostatic vital signs in the ED setting. First, further research is needed to identify more reliable and valid screening tools, such as serum osmolality or urinespecific gravity, for identifying the volume-deficient ED patient. Second, factors that might contribute to the variation in orthostatic vital signs in ED patients, such as autonomic dysfunction, pain, fright, or concomitant medical conditions, should be studied. CONCLUSION There is a w i d e r - t h a n - e x p e c t e d variation in orthostatic vital signs, presumably among euvolemic ED patients. Many normal patients may have what we have considered in the past to be orthostatic vital signs syno n y m o u s w i t h h y p o v o l e m i a . Although orthostatic vital signs might differentiate the ED patient with a massive volume deficit, in this group of patients it would be unsafe and unnecessary to insist on the standing position.
REFERENCES 1. Booklnan LB, Kelley Simoneau J: The ear!y assessment of hypovolemia: Postural vital signs. JEN 1977; Sept/Oct:43 45. 2. Williams TM, Knopp 9.: The clinical use of orthostatic vital signs, in Roberts JR, Hedges JR (eds): Clinical Proceedings in Emergency Medicine. Philadelphia, WB Saunders, 1985, p 367-372. 3. Lanros NE: Assessment and Intervention in Emergency Nursing, ed 2. Bowie, Maryland, Brady, 1983, p 39. 4. Branch WT: Syncope and dizziness, in Branch WT (ed): Office Practice of Medicine. Philadelphia, WB Saunders, 1982, p 334-335. 5. GorolI AH, May LA, MulIey AG (eds): Evaluation of syncope and evaluation of dizziness, in: Primary Care Medicine. Philadelphia, JB Lippincott, 1981, p 76, 621. 6. Branch WT: Approach to syncope. J Gen Int Med i986;l:49 58. 7. Barker LR, Gordon B, Moses H: Dizziness, in Barker LR, Burton JR, Zieve PD (eds): Principles of Ambulatory Medicine. Baltimore, Williams & Wilkins, 1982, p 841.
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19. Zuckerman GR: Gastrointestinal bleeding, in Orland MJ, Saltman RJ (eds): Manual of Medical Therapeutics, ed 25. Boston, Little, Brown and Co, 1986, p 232.
31. Thuesius O: Pathophysiological classification and d i a g n o s i s of o r t h o s t a t i c h y p o t e n s i o n . Cardiology 1976~61(suppl 1):180-190.
20. Fletcher RH, Fletcher SW, Wagner EH: Clinical Epidemiology The Essentials, ed 2. Baltimore, Williams & wilkins, 1988, p 19-4i.
32. Schatz IJ: Orthostatic hypotension: I. Functional and nenrogenic causes. Arch Intern M e d 1984;144: 773-777.
2i. Start I: Clinical studies on incoordination of the circulation, as determined by the response to arising. J Clin Invest 1943;22:813-826.
33. Schatz I~: Orthostatic hypotension IL Clinicai diagnosis~ t e s t i n g , and t r e a t m e n t . Arch I n t e r n M e d 1984; 144:1037-1041.
11. Gregerman RI: Metabolic and endocrinologic problems, in Barker LR, Burton JR, Zieve PD (eds): Principles of Ambulatory Medicine. Baltimore, Williams & Wiikins, 1982, p 667.
22. Guyton A: Textbook of Medical Physiology, ed 7. Philadelphia~ WB Saunders, 1986.
34. Cain HD: Flint's Emergency Treatment and Management, ed 6. Philadelphia, WB Saunders, 1980, p 610.
23. 8chatz IF: Orthostatic hypotension: Diagnosis and treatment. Hosp Prac 1984;19:59-69.
12. Milstein S~ Reyes WJ, Benditt DG: Upright body tilt for evaluation of 'patients with recurrent, unexplained syncope. PACE 1989;12:ii7-124.
24. Sodeman WA, 8odeman TM: Pathologic Physiology Mechanisms of Disease, ed 7. Philadelphia, WB Saunders, 1985.
35. Ployer J: The Physician's Puls&Watch; or an Essay to Explain the Old Art of Feeling the Pulse, and to Improve it by the Help of a Pulse Watch. London, Prince's Arms in St Paul's Church-Yard, 1707.
13. Critikon: Survey of Studies Involving the Dinamap Vital Signs Monitor. Tampa~ Florida, Critikon, 1986.
25. Johnson JM, Niederberger M, Robell LV, et ah Com~ petition between cutaneous vasodilator and vasoconstrictor reflexes in man. [ AppI Physiol i973;35: 798-803.
8. Shapiro JI, Schrier RW: Renal diseases, fluid and electrolyte disorders , and hypertension, in Schrier RW (ed): Medicine Diagnosis and Treatment. Boston, Little, Brown and Co, 1988, p 131. 9. Hofeldt FD, Ridgway EC: Metabolism and endocrinology~ in Schrier RW (ed): Medicine Diagnosis and Treatment. Boston, Little, Brown and Co, 1988, p 347. 10. Gabow PA, Peterson LN: Disorders of potassium metabolism, in 8chrier RW ted}: Renal and Electrolyte Disorders, ed 2. Boston, Little, Brown and Co, 1980, p 183.
14. Schulte D: A comparison of time intervals after posture change when measuring pulse and blood pressure in healthy elderly and nouelderly subjects. Master's thesis~ University of Colorado, Denver, 1986. 18. Iwerson-Moore K, N e w t o n K: Orthostatic heart rates and blood pressures in healthy young women and men. Heart Lung 1986;15:611-617. 16. Kennedy GT, Crawford MH: Optimal position and timing of blood pressure and heart rate measurements to detect orthostatic changes in patients with ischemic heart disease. [ Card Rehab 1984;4:219-223. 17. Milligan Metheny N, Snively WD: Nurse's Handbook of Fluid Balance, ed 4. Philadelphia, JB Lippincott, 1983. 18. Kroenke K: Orthostatie hypotension. West J Med
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36. Schneider E, Truesdell D: A statistical study of the pulse rate and the arterial blood pressures in recumbency, standing, and after a standard exercise. A m J Physiol 1922;61:429-474.
26. Lind AR, Leithead CS, McNicol GW: Cardiovascular changes during syncope induced by tilting men in heat. J AppI Physiol 1968;25:268-276.
37. Currens JH: A comparison of the blood pressure in the lying and standing positions: A study of five hundred m e n and five h u n d r e d w o m e n . A m Heart J 1948;35:646-654.
27. Lipsitz LA, Storch HA, Minaker KL, et al: Intra-individual variability in postural blood pressure in the elderly. Clin Sci 1985;69:337 341.
38. Knopp R, Claypool R~ Leonardi D: Use of the tilt test in measuring acute blood loss. A n n Emerg Med 1980;9:72-75.
28. Tomaszewski CA, Cline DM, Whitley TW: Effects of acute ethanol ingestion on orthostatic vital signs (abstract). Ann Emerg Med 1989;18:438.
39. Levitt MA, Lieberman M, Lopez B: Evaluation of the tilt test in an adult emergency department population (abstract). Ann Emerg Med 1989;18:439.
29. Fuchs SM, Jaffe DM: Evaluation of the "tilt test" in children. Ann Emerg Med 1987;16:386-390. 30. Bergman GE, Reisner FF, Anwar iV.A: Orthostatic changes in normovolemic children: An analysis of the
Annals of Emergency Medicine
40. Mannix FL: Hemorrhagic shock, in Rosen P, Baker FJ II, Barkin RM leds]: Emergency Medicine: Concepts and Clinical Practice, ed 2. St Louis, CV Mosby, 1988, p 179-187.
20:6 June 1991
