INFLUENCE OF NORMOVOLEMIC ANEMIA ON DOPPLER-DERIVED BLOOD VELOCITY RATIOS OF ABDOMINAL SPLANCHNIC VESSELS IN CLINICALLY NORMAL DOGS

Influence of immune-mediated hemolytic anemia on flow velocities in the portal vein and caudal vena cava measured by use of pulsed-wave Doppler ultrasonography in dogs

OBJECTIVE To compare blood flow velocities of the portal vein (PV) and caudal vena cava (CVC) measured by use of pulsed-wave Doppler ultrasonography in clinically normal dogs and dogs with primary immune-mediated hemolytic anemia (IMHA). ANIMALS 11 client-owned dogs admitted to a veterinary teaching hospital for management of primary IMHA and 21 staff- or student-owned clinically normal dogs. PROCEDURES Flow velocities in the PV and CVC at the porta hepatis were evaluated in conscious unsedated dogs with concurrent ECG monitoring; evaluations were performed before dogs with IMHA received heparin or blood transfusions. Three measurements of peak velocity at end expiration were obtained for each vessel, and the mean was calculated. Results were compared between IMHA and control groups. RESULTS Mean ± SD blood flow velocity in the CVC differed between control (63.0 ± 18.6 cm/s) and IMHA (104 ± 36.9 cm/s) groups. Variance in dogs with IMHA was significantly greater than that for the clinically normal dogs. No significant difference in blood flow velocity in the PV was detected between IMHA and control dogs. CONCLUSIONS AND CLINICAL RELEVANCE Higher blood flow velocities were detected by use of pulsed-wave Doppler ultrasonography in the CVC of dogs with naturally occurring IMHA and may be used to predict anemia in patients suspected of having IMHA.

Hemocytometric Measures Predict the Efficacy of Oral Rehydration for Children with Postural Tachycardia Syndrome

OBJECTIVE

To explore whether hemocytometric measures could be qualified predictors for the effect of oral rehydration salts (ORS) in children with postural tachycardia syndrome (POTS).

STUDY DESIGN

Thirty-five children with POTS and 29 healthy children were enrolled. General information, hemodynamic status, and baseline hemocytometric variables were collected. Children with POTS received ORS therapy and were followed up for 3 months. The independent risk factors of developing POTS were explored. A receiver-operating characteristic curve was used to evaluate predictive value of hemocytometric variables for therapeutic effectiveness of ORS therapy.

RESULTS

Children with POTS had larger mean corpuscular volume (MCV) and lower mean corpuscular hemoglobin concentration (MCHC) values than controls (P < .05). The baseline MCV values positively correlated with heart rate elevation from supine to upright (r = 0.294, P < .05). Both larger MCV and lower MCHC values were independent risk factors of developing POTS (for MCV, P < .05, OR 1.222; for MCHC, P < .05, OR 0.936). In children with POTS, responders to ORS had baseline lower MCV and higher MCHC than nonresponders (P < .05). The receiver-operating characteristic curve for the predictive value of MCHC showed that area under the curve was 0.73.

CONCLUSIONS

MCHC values could be used to predict the effectiveness of ORS for treating POTS in children.

Low iron storage and mild anemia in postural tachycardia syndrome in adolescents

OBJECTIVE

We reported low iron storage in neurally mediated syncope (NMS). While reduced red cell mass indicative of anemia has been reported in POTS, iron indices and hemoglobin (Hb) data were not reported. We investigated whether POTS, like NMS, is associated with low iron storage and anemia.

METHODS

Thirty two children evaluated in 2007 and 2008 for probable POTS by a standing or tilt test or both at Texas Children's Hospital were included in a retrospective study. We measured serum ferritin (SF) and Hb values. We defined iron deficiency as SF < 12 μg/L, low iron storage as SF ≤ 25 μg/L, anemia as low Hb values for age and sex, and POTS as ≥2 symptoms of orthostatic intolerance >3 months and increased HR of >30 BPM or HR of >120 BPM within 10 min of standing or 70° tilt.

RESULTS

Twenty four children had POTS, ages 12-18 years, 17 (71 %) were females. Value range (median) of SF 2-289 μg/L (25), Hb 11.5-14.6 (12.5) in females and 12-15.9 g/L (13.6) in males. Patients with POTS, when compared with normal US pediatric population had higher prevalence of low iron storage (50 vs. 14 %), iron deficiency (25 % of teenage girls vs. 9 %, and 16 % of teenage boys vs. 1 %), and anemia (18 % of teenage girls vs. 1.5 %, and 43 % of teenage boys vs. 0.1 %).

INTERPRETATION

Low iron storage and mild anemia are associated with POTS suggesting that low iron storage is a potentially pathophysiologic factor in both POTS and NMS.