title: Right-to-left shunt and risk of decompression illness with cochleovestibular and cerebral symptoms in divers: case control study in 101 consecutive dive accidents.
abstract: OBJECTIVE
  We investigated the role of right-to-left shunt with standardized transcranial Doppler ultrasonography in a large population of divers referred for symptoms of decompression illness.
  
  
  METHODS
  Case series compared with a control group.
  
  
  METHODS
  Military teaching hospital, hyperbaric unit.
  
  
  METHODS
  Patients were 101 consecutive divers with clinical evidence of decompression illness and a control group of 101 healthy divers.
  
  
  METHODS
  Specification of the type of decompression illness involved and detection/evaluation of right-to-left shunt by standardized transcranial Doppler. The degree of right-to-left shunt was defined as major if the number of high-intensity transient signals in the middle cerebral artery was >20.
  
  
  RESULTS
  We evaluated the odds ratios by logistic regression analysis with vs. without right-to-left shunt for subjects with cochleovestibular symptoms, cerebral decompression illness, spinal decompression illness, and Caisson sickness. Of the 101 divers presenting with decompression illness, transcranial Doppler detected a right-to-left shunt in 59 (58.4%), whereas control subjects demonstrated a right-to-left shunt in 25 cases (24.8%; odds ratio, 4.3; 95% confidence interval, 2.3-7.8; p=.09). When a right-to-left shunt was detected, the right-to-left shunt was major in 12 of 25 patients in the control group and in 49 of 59 patients in the decompression illness group (odds ratio, 8.7; 95% confidence interval, 4.2-18.0; p<.001). Within the decompression illness group, the proportion of major right-to-left shunt was 24 of 34 (odds ratio, 29.7; 95% confidence interval, 10.0-87.2; p<.0001) in the cochleovestibular subgroup, 13 of 21 (odds ratio, 24.1, 95% confidence interval, 6.8-86.0, p< 0.0001) in the cerebral decompression illness subgroup, ten of 31 (odds ratio, 3.9; 95% confidence interval, 1.5-10.3; p<.01) in the spinal decompression illness subgroup, and two of two (odds ratio, 1.1; 95% confidence interval, 0.2-5.7; p=.9) in the subgroup of divers with Caisson sickness.
  
  
  CONCLUSIONS
  Based on our results, we conclude that major right-to-left shunt was associated with an increased incidence of cochleovestibular and cerebral decompression illness, suggesting paradoxical embolism as a potential mechanism.
authors.affiliation: Military Teaching Hospital, Service de Réanimation, Toulon-Naval, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Cantais
authors.forename: Pierre
authors.initials: P
authors.lastname: Louge
authors.forename: Alain
authors.initials: A
authors.lastname: Suppini
authors.forename: Philip P
authors.initials: PP
authors.lastname: Foster
authors.forename: Bruno
authors.initials: B
authors.lastname: Palmier
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015834:Cochlear Diseases / Q000453:epidemiology / Q000209:etiology; D003665:Decompression Sickness / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D004242:Diving / Q000293:injuries*; D019320:Embolism, Paradoxical / Q000150:complications*; D005260:Female; D005602:France / Q000453:epidemiology; D006344:Heart Septal Defects, Atrial / Q000150:complications* / Q000000981:diagnostic imaging; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D012306:Risk; D017585:Ultrasonography, Doppler, Transcranial; D015837:Vestibular Diseases / Q000453:epidemiology / Q000209:etiology