Right-to-left shunt and risk of decompression illness with cochleovestibular and cerebral symptoms in divers: Case control study in 101 consecutive dive accidents

• Published in: Critical care medicine Vol. 31; no. 1; pp. 84 - 88
• Main Authors: Cantais, Emmanuel, Louge, Pierre, Suppini, Alain, Foster, Philip P, Palmier, Bruno
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD by the Society of Critical Care Medicine and Lippincott Williams & Wilkins 01-01-2003; Lippincott
• Subjects: Adult; Biological and medical sciences; Case-Control Studies; Cochlear Diseases - epidemiology; Cochlear Diseases - etiology; Decompression Sickness - diagnostic imaging; Decompression Sickness - epidemiology; Decompression Sickness - etiology; Diving - injuries; Embolism, Paradoxical - complications; Female; France - epidemiology; Heart Septal Defects, Atrial - complications; Heart Septal Defects, Atrial - diagnostic imaging; Humans; Incidence; Logistic Models; Male; Medical sciences; Risk; Transport. Aerospace. Diving. Altitude; Traumas. Diseases due to physical agents; Ultrasonography, Doppler, Transcranial; Vestibular Diseases - epidemiology; Vestibular Diseases - etiology; Doppler ultrasound study; Persistent fetal circulation; Pathogenesis; Right to left shunt; Middle cerebral artery; Cardiovascular disease; Paradoxical embolism; cochleovestibular decompression illness; Transcranial route; transcranial Doppler; Heart disease; ENT disease; Complication; Diving; Vestibular syndrome; patent foramen ovate; Neurological disorder; Sonography; Human; Nervous system diseases; Congenital disease; Decompression sickness; decompression illness; Risk factor; Cochlea; Ostium secundum
• ISSN: 0090-3493; 1530-0293
• DOI: 10.1097/00003246-200301000-00013

OBJECTIVEWe 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.
DESIGNCase series compared with a control group.
SETTINGMilitary teaching hospital, hyperbaric unit.
PATIENTSPatients were 101 consecutive divers with clinical evidence of decompression illness and a control group of 101 healthy divers.
INTERVENTIONSpecification 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.
MEASUREMENTS AND MAIN RESULTSWe 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.
CONCLUSIONBased 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.