Canadian Journal of Anesthesia

, 49:185

Baseline heart rate may predict hypotension after spinal anesthesia in prehydrated obstetrical patients

Obstetrical and Pediatric Anesthesia



Hypotension is the most frequent complication of spinal anesthesia in pregnant patients. This study was designed to identify patients at risk for postspinal hypotension based on preoperative vital signs before and after an orthostatic challenge.


Forty healthy women scheduled for elective Cesarean section were enrolled in this prospective trial. Blood pressure (BP) and heart rate (HR) were recorded with the patient in the lateral supine position and after standing up. After a bupivacaine spinal anesthetic, BP was obtained every two minutes for 30 min. Ephedrine treatment was administered based on the degree of hypotension observed. Hemodynamic parameters were correlated to ephedrine requirements (Spearman’s rank order correlation).


There was a significant correlation in baseline maternal HR and ephedrine requirements (P = 0.005). The degree of orthostatic changes in mean arterial BP and HR did not correlate with postspinal hypotension.


Baseline HR may be predictive of obstetric spinal hypotension. Higher baseline HR, possibly reflecting a higher sympathetic tone, may be a useful parameter to predict postspinal hypotension.

La fréquence cardiaque initiale peut être prédictive d’hypotension après la rachianesthésie chez des patientes obstétricales préhydratées



Chez les femmes enceintes, l’hypotension est la plus fréquente complication de la rachianesthésie. Notre étude veut identifier les patientes à risque d’hypotension postsrachidienne en notant les signes vitaux d’avant et après la provocation orthostatique.


Quarante femmes en bonne santé, devant subir une césarienne, ont participé à cet essai prospectif. La tension artérielle (TA) et la fréquence cardiaque (FC) ont été notées alors que la patiente est en décubitus latéral, puis en station debout. La TA a été enregistrée toutes les deux minutes pendant 30 min à la suite de l’administration rachidienne de bupivacaïne. De l’éphédrine a été donnée en fonction du degré d’hypotension observée. On a mis en corrélation les paramètres hémodynamiques et les besoins d’éphédrine (corrélation des rangs de Spearman).


Une corrélation significative a été notée entre la FC de base et les besoins d’éphédrine (P = 0,005). Il n’y a pas eu de corrélation entre le degré des modifcations orthostatiques de la TA et de la FC moyennes et l’hypotension postrachidienne.


La FC initiale peut être prédictive d’hypotension rachidienne en obstétrique. Une FC initiale élevée, pouvant exprimer un tonus sympathique plus important, peut être un paramètre prédictif intéressant d’hypotension postrachidienne.


  1. 1.
    Corke BC, Datta S, Osthdmer GW, Weiss JB, Alper MH. Spinal anaesthesia for caesarean section. The influence of hypotension on neonatal outcome. Anaesthesia 1982; 37: 658–62.PubMedCrossRefGoogle Scholar
  2. 2.
    Ramanathan S, Grant GJ. Vasopressor therapy for hypotension due to epidural anesthesia for cesarean section Acta Anaesthesiol Scand 1988; 32: 559–65.PubMedCrossRefGoogle Scholar
  3. 3.
    Gutsche BB. Prophylactic ephedrine preceding spinal analgesia for cesarean section. Anesthesiology 1976; 45: 462–5.PubMedCrossRefGoogle Scholar
  4. 4.
    Kee WDN, Khaw KS, Lee BB, Lau TK, Gin T. A dose-response study of prophylactic intravenous ephedrine for the prevention of hypotension during spinal anesthesia for cesarean delivery. Anesth Analg 2000; 90: 1390–5.CrossRefGoogle Scholar
  5. 5.
    Kluger MT. Ephedrine may predispose to arrhythmias in obstetric anaesthesia (Letter). Anaesth Intensive Care 2000; 28: 336.PubMedGoogle Scholar
  6. 6.
    Phelan JP. Pulmonary edema in obstetrics. Obstet Gynecol Clin North Am 1991; 18: 319–31.PubMedGoogle Scholar
  7. 7.
    Baraff LJ, Schriger DL. Orthostatic vital signs: variation with age, specificity, and sensitivity in detecting a 450-mL blood loss. Am J Emerg Med 1992; 10: 99–103.PubMedCrossRefGoogle Scholar
  8. 8.
    Smith JJ, Ebert TJ. General response to orthostatic stress,In: Smith JJ (Ed.). Circulatory Response to Upright Posture. Boca Raton: CRC Press, 1990: 1–46.Google Scholar
  9. 9.
    Streeten DHP. Orthostatic intolerance. A historical introduction to the pathophysiological mechanisms. Am J Med Sci 1999; 317: 78–87.PubMedCrossRefGoogle Scholar
  10. 10.
    Gant NF, Whalley PJ, Everett RB, Worley RJ, MacDonald PC. Control of vascular reactivity in pregnancy. Am J Kidney Dis 1987; 9: 303–7.PubMedGoogle Scholar
  11. 11.
    Pyörälä T. Cardiovascular response to the upright position during pregnancy. Acta Obstet Gynecol Scand 1966;45(Suppl 5): 1–116.PubMedGoogle Scholar
  12. 12.
    Greene NM. Physiology of Spinal Anesthesia, 3rd ed. Baltimore/London, Williams & Wilkins: 1981.Google Scholar
  13. 13.
    Kinsella SM, Norris MC. Advance prediction of hypotension at cesarean delivery under spinal anesthesia. Int J Obstet Anesth 1996; 5: 3–7.PubMedCrossRefGoogle Scholar
  14. 14.
    Clark SL, Cotton DB, Pivarnik JM, et al. Position change and central hemodynamic profile during normal third-trimester pregnancy and post partum. Am J Obstet Gynecol 1991; 164: 883–7.PubMedGoogle Scholar
  15. 15.
    Heesch CM, Rogers RC Effects of pregnancy and progesterone metabolites on regulation of sympathetic out-flow. Clin Exp Pharmacol Physiol 1995; 22: 136–42.PubMedCrossRefGoogle Scholar

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© Canadian Anesthesiologists 2002

Authors and Affiliations

  1. 1.Departments of AnesthesiologyUniversity of Florida College of MedicineGainesvilleUSA
  2. 2.Departments of Obstetrics and GynecologyUniversity of Florida College of MedicineGainesvilleUSA
  3. 3.Department of AnesthesiologyGainesvilleUSA

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