Orthostatic Vital Signs and Hypovolemia

1. Orthostatic Vital Signs and Hypovolemia Adrienne Tsai, MD December 9, 2003

2. Orthostatic Vitals Signs/Tilt Test • Measurement of changes in blood pressure and heart rate from a supine to standing position • Clinicians should wait 2 minutes before measuring supine vital signs and wait 1 minute before measuring standing vital signs • Frequently used as indicators of intravascular volume status in the emergency setting

3. Clinical Studies • Knopp R, et al. Use of the Tilt Test in Measuring Acute Blood Loss. Ann Emerg Med. 9: 29-32 1980. • Johnson DR, et al. Dehydration and Orthostatic Vital Signs in Women with Hyperemesis Gravidarum. Acad Emerg Med. 2:692-697 1995. • Levitt MA, et al. Evaluation of the Tilt Test in an Adult Emergency Medicine Population. Ann Emerg Med. 21:713-718 1992.

4. Knopp et al. • Prospective study at the Central California Blood Bank • Sample of 100 healthy volunteers, ages 17-55 yo, 56 males, 44 females • Measured orthostatics prior to blood donation. HR and BP recorded supine, sitting (T0,T1,T2) and standing at (T0,T1,T2). • Divided into two groups : Grp 1 (56 subjects) phlebotomized a total of 450 cc. Grp 2 (44 subjects) phlebotomized 500 cc initially and then 1 L. Measured orthostatics following each donation.

5. Results : Knopp et al.

6. Results: Knopp et al. • From supine to sitting, there were no significant changes in HR or BP • HR taken at T1 (1 minute after standing) showed the largest change (45.7/min) • Blood volume phlebotomized was measured by Cr51 tagged red cells and ranged from 9.7-29.6% in group II subjects (1 L) . There was no correlation with symptoms or severity of change in HR

7. Knopp et al. Conclusions 1. BP was not useful in detecting presence or absence of acute blood loss up to 1 L 2. Pulse change(>30 /min) and the presence or absence of symptoms were the criteria used for the tilt test. A positive tilt test indicated an extremely high probability that blood loss occurred. A negative tilt test indicated that acute loss of 1 L was unlikely. The major value of the test is in detecting blood loss of 1 L or greater. Weakness Only applicable to a population with similar characteristics : young , healthy adults with acute blood loss.

8. Johnson et al. • Prospective observational study • Sample of 23 pregnant women presenting to an urban teaching hospital, chief complaint nausea and vomiting of 24 hours duration, +hcg,  16 weeks, urine SG  1.025 or urinary ketones  40 mg/dL • Measured orthostatic vital signs and serum electrolytes pre and post hydration. Each patient had an infusion of 6 L of fluids over 12 hours • In comparing pre and post hydration values, significant differences were noted for pulse rate and SBP but not for DBP

9. Results : Johnson et al.

10. Johnson et al. • Conclusions -None of the various vital sign change cutoffs achieved sensitivity  80% for dehydration  5% of total body weight - Not sensitive or specific enough to use as a screening test. -Improvement can serve as indicative of rehydration • Weaknesses -This is GI fluid loss, not applicable to acute blood loss - Population of pregnant patients with changes in cardiovascular system - None of pts significantly dehydrated enough to be symptomatic while standing - Could not ascertain each pt was fully hydrated, each pt was own control - Small sample size

11. Levitt et al. • Prospective Study in urban ED • Sample of 202 ill adult patients with complaints suggestive of blood loss (group 1=36 pts), or dehydration (group 2 = 166 pts) and a control, (21) healthy individuals • Measured orthostatic vital signs, total body water deficit (TBWD) based on serum osm, BUN/Cr, Hct and PE findings suggestive of dehydration • -Linear regression models were constructed for all continuous variables with TBWD, BUN/Cr. Dependent variables included HR, SBP, DBP, Age -Compared orthostatic vital sign measurements between ill patients and control

12. Results : Levitt et al. : Orthostatic measurements compared between study samples and healthy volunteers

13. Results : Levitt et al. Change in HR and age showed very small association with level of dehydration and changes in SBP and DBP demonstrated no significant association with the level of dehydration. There was also a wide variation in orthostatic vital sign measurements in samples from both healthy and ill patients.

14. Levitt et al. • Conclusions -Lack of usefulness of orthostatic vital signs HR, SBP, DBP all demonstrate clinically negligible association with level of dehydration -No clinically significant difference in HR, SBP, DBP in patients with blood loss vs. healthy controls -There is a wide variation in HR, BP from supine to standing whether in a dehydrated, blood loss or healthy state •Weaknesses -There is no gold standard of measurement of dehydration - TBWD was only 3.9+/-3% in this study

15. Confirmatory Studies • Baraff et al. (Am J Emer Med 1992) : Pulse rise is more sensitive than BP in detecting a 450 mL blood loss, no parameter was sufficiently sensitive to be clinically useful • Koziol et al. (Ann Emer Med 1991) : There is a wider than expected variation in orthostatic vital signs among presumed euvolemic patients, 43% had “+” orthostatic vital signs • McGee et al (JAMA 1999) : In diagnosing hypovolemia, few PE findings have proven utility, clinicians should measure serum electrolytes,Bun/Cr

16. HUP ism • There is no good evidence supporting the use of orthostatic vital signs as a screening test for hypovolemia in the emergency department setting • An improvement in orthostatic vital signs may be clinically useful in assessing rehydration