title: Epidural space identification: a meta-analysis of complications after air versus liquid as the medium for loss of resistance.
abstract: BACKGROUND
  The best method for identifying the epidural space for neuraxial blocks is controversial. We conducted this meta-analysis to test the hypothesis that loss of resistance with liquid reduces complications with epidural placement.
  
  
  METHODS
  The MEDLINE, EMBASE, and Cochrane databases were searched for prospective, randomized studies comparing air versus liquid as the medium for loss of resistance during epidural space identification in adults. Data were abstracted from 5 studies (4 obstetric and 1 nonobstetric) (n = 4422 patients) that met inclusion criteria and analyzed for the following 6 outcomes: difficult catheter insertion, paresthesia, intravascular catheter insertion, accidental dural puncture, postdural puncture headache, and partial block.
  
  
  RESULTS
  The overall risk differences for adverse outcome between the different mediums were not statistically different for the obstetric population. A small, but statistically significant, risk difference for postdural puncture headache was observed when fluid was used during epidural placement for chronic pain management.
  
  
  CONCLUSIONS
  Larger studies that overcome limitations of heterogeneity across studies and a relatively infrequent occurrence of complications are required to determine the optimal medium for loss of resistance during epidural block.
authors.affiliation: Department of Anesthesiology and Postoperative Intensive Care Medicine, University of Cologne, Cologne, Germany. robert.schier@gmx.ne
authors.forename: Robert
authors.initials: R
authors.lastname: Schier
authors.forename: Diana
authors.initials: D
authors.lastname: Guerra
authors.forename: Jorge
authors.initials: J
authors.lastname: Aguilar
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Pratt
authors.forename: Mike
authors.initials: M
authors.lastname: Hernandez
authors.forename: Krishna
authors.initials: K
authors.lastname: Boddu
authors.forename: Bernhard
authors.initials: B
authors.lastname: Riedel
mesh_terms: D000328:Adult; D000388:Air; D000698:Analgesia / Q000009:adverse effects* / Q000295:instrumentation; D016362:Analgesia, Obstetrical / Q000009:adverse effects; D000765:Anesthesia, Conduction / Q000009:adverse effects* / Q000295:instrumentation; D000773:Anesthesia, Obstetrical / Q000009:adverse effects; D002404:Catheterization / Q000009:adverse effects; D004388:Dura Mater / Q000293:injuries; D004824:Epidural Space / Q000033:anatomy & histology*; D005260:Female; D006261:Headache / Q000209:etiology; D006801:Humans; D007268:Injections, Epidural / Q000009:adverse effects; D008297:Male; D009407:Nerve Block / Q000009:adverse effects* / Q000295:instrumentation; D010292:Paresthesia / Q000209:etiology; D011247:Pregnancy; D011312:Pressure; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D013594:Syringes; D017211:Treatment Failure