Heart rate variability-guided prophylactic treatment of severe hypotension after subarachnoid block for elective cesarean delivery.
BACKGROUND
Baseline low-to-high frequency ratio (LF/HF) of heart rate variability predicted hypotension after subarachnoid block (SAB). LF/HF-guided treatment of hypotension with vasopressors or colloids was investigated.


METHODS
In 80 women scheduled to undergo cesarean delivery during SAB, LF/HF and systolic blood pressure (SBP) were analyzed. Patients were randomly assigned to a control group (n = 40) or a treatment group (n = 40). Control patients were assigned by their baseline LF/HF to one of two subgroups: LF/HF less than 2.5 or LF/HF greater than 2.5. Treatment patients with baseline LF/HF greater than 2.5 were treated with vasopressor infusion right after SAB (n = 20) or colloid prehydration until LF/HF decreased below 2.5 (n = 20). The incidences of hypotension (SBP < 80 mmHg) and hypertension (SBP > 140 mmHg) were investigated. LF/HF is presented as median and range, and SBP is presented as mean +/- SD.


RESULTS
Three of 17 control patients with low baseline LF/HF (1.7 [1.3/1.8]) demonstrated hypotension, and mean SBP remained stable (lowest SBP = 105 +/- 14 mmHg). In contrast, 20 of 23 control patients with high baseline LF/HF (3.8 [3.3/4.8]; P < 0.0001 vs. low baseline LF/HF) demonstrated hypotension after SAB: lowest SBP = 78 +/- 15 mmHg (P < 0.0001 vs. lowest SBP of control group with low baseline LF/HF). LF/HF-guided vasopressor therapy prevented hypotension in 19 of 20 patients: baseline SBP = 123 +/- 15 mmHg, lowest SBP = 116 +/- 17 mmHg. Mean prophylactic colloid infusion of 1,275 +/- 250 ml reduced elevated baseline LF/HF from 5.4 (4.1/7.5) to 1.3 (0.8/1.59) (P < 0.0001). Hypotension was prevented in 17 of 20 patients: baseline SBP = 115 +/- 13 mmHg, lowest SBP = 104 +/- 19 mmHg. No hypertensive episode was recognized.


CONCLUSIONS
LF/HF may be a tool to guide prophylactic therapy of patients at high risk for hypotension after SAB. Vasopressor therapy tended to be more effective compared with colloid prehydration.
Department of Anaesthesiology and Intensive Care Medicine, University-Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany. hanss@anaesthesie.uni-kiel.de
Robert
R
Hanss
Berthold
B
Bein
Helga
H
Francksen
Wiebke
W
Scherkl
Martin
M
Bauer
Volker
V
Doerges
Markus
M
Steinfath
Jens
J
Scholz
Peter H
PH
Tonner
D000328:Adult; D000773:Anesthesia, Obstetrical / Q000009:adverse effects*; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D002585:Cesarean Section; D003102:Colloids; D005260:Female; D005440:Fluid Therapy; D006339:Heart Rate; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000517:prevention & control*; D011247:Pregnancy; D011446:Prospective Studies; D013599:Systole
D003102:Colloids