title: Hypotension from spinal anesthesia in patients aged greater than 80 years is due to a decrease in systemic vascular resistance.
abstract: OBJECTIVE
  To determine the exact mechanism underlying spinal anesthesia-induced hypotension in the elderly patient.
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  Operating room (OR) in a general hospital.
  
  
  METHODS
  Records from 60 consecutive patients over 80 years of age, who underwent hip fracture repair (intramedullary nail or compression hip screw) during spinal anesthesia were studied. After injection of isobaric 0.5% bupivacaine in the L(3)-L(4) intervertebral space in the lateral decubitus position, patients were turned supine. Acetate Ringer's solution (300 mL) was infused over 30 minutes after subarachnoid puncture. A decrease in systolic arterial pressure to less than 100 mmHg was treated with an intravenous injection of 5 mg ephedrine. The hypotension group (n=18) comprised patients who required ephedrine during the 30 minutes after the puncture, and the nonhypotension group (n=42) consisted of patients who maintained stable arterial pressure with crystalloid infusion only.
  
  
  METHODS
  Cardiac output (CO) and stroke volume variation (SVV) every 20 seconds using the Vigileo-FloTrac system continuously from arrival in the operating room (OR) to 30 minutes after the subarachnoid puncture were recorded. Serial changes in systemic vascular resistance (SVR), CO, and SVV from baseline after puncture were compared between the two groups.
  
  
  RESULTS
  The decrease in SVR over 20 minutes after the puncture was significantly greater in the hypotension group than the nonhypotension group (P = 0.047). Cardiac output was stable in the two groups. Stroke volume variation in the first 10 minutes after the puncture increased to similar levels in the two groups, then decreased gradually to baseline. No significant differences were noted in circulatory parameters on arrival at the OR.
  
  
  CONCLUSIONS
  A decrease in SVR, not CO, is the main mechanism of hypotension seen during spinal anesthesia in elderly patients.
authors.affiliation: Department of Anesthesiology, Kansai Denryoku Hospital, Osaka 553-0003, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nakasuji
authors.forename: Soon Hak
authors.initials: SH
authors.lastname: Suh
authors.forename: Masataka
authors.initials: M
authors.lastname: Nomura
authors.forename: Mitsuyo
authors.initials: M
authors.lastname: Nakamura
authors.forename: Norie
authors.initials: N
authors.lastname: Imanaka
authors.forename: Masuji
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kae
authors.initials: K
authors.lastname: Nakasuji
mesh_terms: D000367:Age Factors; D000369:Aged, 80 and over; D000775:Anesthesia, Spinal / Q000009:adverse effects* / Q000379:methods; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000009:adverse effects; D001863:Bone Screws; D002045:Bupivacaine / Q000008:administration & dosage / Q000009:adverse effects; D002302:Cardiac Output / Q000187:drug effects; D016022:Case-Control Studies; D004809:Ephedrine / Q000627:therapeutic use; D005260:Female; D005594:Fracture Fixation, Intramedullary / Q000379:methods; D006620:Hip Fractures / Q000601:surgery; D006801:Humans; D007022:Hypotension / Q000139:chemically induced*; D008297:Male; D012189:Retrospective Studies; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects*
chemical_list: D000779:Anesthetics, Local; D004809:Ephedrine; D002045:Bupivacaine