Intensive Care Med DOI 10.1007/s00134-010-1821-9 ORIGINAL Jacques Bessereau Long-term outcome of iatrogenic gas embolism Nicolas Genotelle Cendrine Chabbaut Anne Huon Alexis Tabah Je´roˆme Aboab Sylvie Chevret Djillali Annane Received: 19 June 2009 Abstract Objective: To establish of 1-year mortality (OR = 4.39, 95% Accepted: 24 January 2010 the incidence and long-term progno- CI 1.46–12.20 and OR = 6.30, 1.71– sis of iatrogenic gas embolism. 23.21, respectively). Among ICU Ó Copyright jointly held by Springer and Methods: This was a prospective survivors, independent predictors of ESICM 2010 inception cohort. We included all 1-year mortality were age consecutive adults with proven iatro- (OR = 1.07, 1.01–1.14), Babinski genic gas embolism admitted to the sign (OR = 6.58, 1.14–38.20) and sole referral academic hyperbaric acute kidney failure (OR = 8.09, center in Paris. Treatment was stan- 1.28–51.21). Focal motor deficits dardized as one hyperbaric session at (OR = 12.78, 3.98–41.09) and 4 ATA for 15 min followed by two Babinski sign (OR = 6.76, 2.24– 45-min plateaus at 2.5 then 2 ATA. 20.33) on ICU admission, and dura- J. Bessereau Á N. Genotelle Á A. Huon Á Inspired fraction of oxygen was set at tion of mechanical ventilation of A. Tabah Á J. Aboab Á D. Annane ()) 100% during the entire dive. Primary 5 days or more (OR = 15.14, General Intensive Care Unit, Hyperbaric endpoint was 1-year mortality. All 2.92–78.52) were independent pre- Centre, Raymond Poincare´ Hospital patients had evaluation by a neurolo- dictors of long-term sequels. (AP-HP), University of Versailles SQY Conclusions: Gas embolism (UniverSud Paris), 104 boulevard Raymond gist, visual field tested by Goldman Poincare´, 92380 Garches, France kinetic perimetry and brain MRI or complicates 2.65 per 100,000 hospi- e-mail: [email protected] CT scan at 6 months and 1 year. talizations, and is associated with Tel.: ?33-1-47107786 Results: From January 1993 to high mortality and morbidity. Babin- Fax: ?33-1-47107783 August 2004, 125 of 4,727,496 hos- ski sign on ICU admission is pitalizations had proven iatrogenic associated with poor prognosis. C. Chabbaut Á S. Chevret gas embolism. The crude mortality De´partement de Biostatistiques et Keywords Iatrogenic Á Informatique Me´dicale, AP-HP, was 25/119 (21%) at 1 year. Cardiac Erm321-INSERM, Saint-Louis Hospital arrest at time of accident and ICU Gas embolism Á Outcome Á Mortality Á (AP-HP), 10 avenue Vellefaux, admission, and SAPS II of 33 or more Sequels Á Glasgow Outcome Scale 75010 Paris, France were independent prognostic factors Introduction obstruction with subsequent ischemia/reperfusion inju- ries. This accident is commonly recognized when sudden Gas embolism is a rare complication of invasive medical neurological, pulmonary or cardiac abnormalities occur or surgical procedures [1]. Gas embolism may originate in during invasive procedures. More subtle cases may be the venous system or in the systemic arterial circulation. diagnosed by echocardiography, transcranial Doppler, CT In the former case, the gaseous embolus may reach the scan or other diagnostic procedures. systemic circulation via pulmonary shunting or via patent Gas embolism is considered as an emergency, and foramen ovale. When the gaseous embolus is in the treatment includes interruption of the embolic procedure, arterial circulation, it may cause transient arterial attempt to extract intravascular gas, external cardiac massage and immediate oxygenation, at best under coma, focal motor deficit, seizures, cardiac arrest, car- hyperbaric conditions. Hyperbaric oxygen therapy (HBO) diovascular collapse and acute dyspnea; (3) evidence of is recommended, although randomized, controlled clinical gas bubble entry in the systemic circulation as noticed trials are lacking [1–3]. Indeed, HBO may reduce gas during a surgical or radiological procedure, or presence of bubble volume by increasing ambient pressure and by gas bubbles in left heart cavities at echocardiography or in inducing blood denitrogenation, which facilitates oxygen cerebral arteries at transcranial Doppler or CT scan. diffusion from the emboli to the surrounding plasma. It Notable exclusion criteria included underlying disease also permits a better oxygenation of ischemic tissues by with a life expectancy of less than 1 month, moribund increasing dissolved-oxygen content in blood and tissues. patients likely to die within 24 h and patients with Finally, HBO may decrease cerebral edema. Potential decompression sickness. disadvantages of HBO include risks associated with the transport of critically ill patients, hyperoxic seizures, Hyperbaric oxygen therapy claustrophobic reactions and barotraumas. Little is known about the morbidity and mortality An identical HBO procedure was used for all patients. We associated with iatrogenic gas embolism. Indeed, the used a multiplace hyperbaric chamber (CxPRO, CO- diagnosis of gas embolism may be difficult in conditions MEXÒ, Marseille, France) pressurized with compressed other than high risk surgery. In addition, when recognized, air at 4 atmospheres absolute (ATA) for 15 min (30 msw iatrogenic gas embolism requires a specific management depth, 405 kPa) followed by two 45-min plateaus at 2.5 and patient referral to a hyperbaric facility. The long-term then 2 ATA (Appendix 1). All intubated patients were follow-up of patients often does not involve the hyperbaric mechanically ventilated in the chamber with 100% oxy- physicians. Thus, unsurprisingly, the few available retro- gen (RCH LAMAÒ). The remaining patients received spective studies showed a wide range of mortality from 5 100% oxygen during the full session via a tight-fitting to 23% and of sequels from 13 to 71% [4–14]. face mask. All patients received intravenous diazepam or We took the opportunity, as a referral center in Paris midazolam, and phenobarbital to prevent hyperoxic sei- and its suburb, to conduct a prospective cohort study with zures. The hyperbaric session was completed by 12 h of careful short-term and 1-year follow-up to determine the normobaric oxygen therapy. mortality and morbidity from proven iatrogenic gas embolism. Data collection Data collection at inclusion Materials and methods Clinical evaluation The following data were recorded: (1) This was a prospective single-center, inception cohort general characteristics including demographics, diagnosis study performed at Raymond Poincare´ University-affili- and recent surgery; (2) severity of illness assessed by vital ated Hospital. The intensive care unit (ICU) has a separate signs, Glasgow Coma Scale score and Simplified Acute unit for HBO. This is the sole public hyperbaric oxygen Physiology Score II (SAPS II) [15]; (3) neurological, facility for Paris and its suburb. Therefore, all cases of cardiac and respiratory symptoms; (4) type and source of iatrogenic gas embolism in this area are referred to our gas embolism; (5) time to HBO treatment; (6) presence center. The protocol was approved by the Comite´ Con- of a patent foramen ovale (PFO); (7) interventions sultatif de Protection des Personnes dans la Recherche including type and doses of vasopressors, and mechanical Biome´dicale of Saint-Germain en Laye (Yvelines, ventilation. France), and informed consent was waived according to the observational nature of the study; all patients received routine standard of care for gas embolism (cardiopulmo- Laboratory variables nary resuscitation, fluid therapy, mechanical ventilation and positive inotropic support whenever needed). Hematological and chemistry data, blood gas determina- tions, electroencephalography and whenever possible magnetic resonance imagings (MRI) or computerized Patients tomography (CT scan) of the brain were recorded. Patients of 18 years of age or above and hospitalized in our hyperbaric center were prospectively enrolled in the Follow-up study if they met all eligibility criteria. Inclusion criteria included: (1) clinical condition at risk for iatrogenic gas During the hospital stay, data were collected for vital embolism; (2) at least one of the following clinical sign: signs, results from laboratory tests and any major interventions performed. The neurological status, as gas embolism. Among these patients, gas embolism was established by a senior neurologist, and mortality were proven in only 125 cases that were referred to the recorded at discharge from the ICU, at discharge from the hyperbaric unit for HBO (Table 1). Six patients (home- hospital, at 6 months and at 1 year. All patients had visual less) were lost to follow-up after hospital discharge. field evaluation tested by Goldman kinetic perimetry and Almost all accidents were air embolism except nine cases brain MRI or CT scan at 6 months and at 1 year following of carbon dioxide gas embolism following coelioscopy or gas embolism. hysteroscopy (Table 2). The main clinical manifestations did not differ between venous and arterial gas embolism, except a higher rate of acute myocardial infarction in case Endpoints of arterial gas embolism (26 vs. 10%, P = 0.03; Table 3). The primary outcome was 1-year mortality. Secondary outcomes were neurological sequels similarly assessed at Mortality ICU discharge, then among ICU survivors at 6 months and 1 year using the Glasgow Outcome Score (1, death; 2, The crude mortality was 14/119 (12%) at ICU discharge, vegetative state; 3, severe disability, i.e., the patient is 19/119 (16%) at hospital discharge, 21/119 (17.6%) at unable to live independently; 4, moderate disability, i.e. 6 months and 25/119 (21%) at 1-year (Fig. 1). the patient is able to live independently but unable to Univariate analysis suggested that, immediately fol- return to work; 5, mild or no disability, i.e., the patient is lowing gas embolism onset, non-survivors were more able to return to work) [16]. likely to present with cardiac arrest (P = 0.0004), car- diovascular collapse (P = 0.005), acute myocardial infarction (P = 0.02), acute kidney failure (P = 0.01) Statistical analysis and disseminated intravascular coagulopathy (P = 0.045) (Table 4).