Post effect of repetitive exposures to pressure nitrogen-induced narcosis on the dopaminergic activity at atmospheric pressure.

Nitrogen at pressure produces a neurological syndrome called nitrogen narcosis. Neurochemical experiments indicated that a single exposure to 3 MPa of nitrogen reduced the concentration of dopamine by 20% in the striatum, a structure involved in the control of extrapyramidal motor activity. This effect of nitrogen was explained by enhanced GABAergic neurotransmission through GABAA receptors and, to a lesser extent, by a decreased glutamatergic input to DA cells through NMDA receptors. The aim of this study was to study, under normobaric conditions, possible alterations of NMDA receptor activity in the substantia nigra pars compacta (SNc) induced by repetitive exposures to nitrogen pressure. Under general anesthesia, male Sprague-Dawley rats were implanted in the striatum with multifiber carbon dopamine-sensitive electrodes and in the SNc with guide cannulae for drug injections. After recovery from surgery, the striatal dopamine level was recorded by voltammetry in freely-moving rats, in normobaric conditions, before and after 5 repetitive exposures to 1MPa of nitrogen (threshold of nitrogen narcosis occurrence in rat). The effect of NMDA receptor activity on DA concentration was investigated using agonist (NMDA) and specific antagonist (AP7) SNc administration. Following repetitive nitrogen exposures, the ability of NMDA to elevate DA concentrations was enhanced. In contrast, after nitrogen exposure AP7 produced a paradoxical increase in DA concentration compared to its inhibitory effect before any exposure. Similar responses were obtained after a single exposure to 3MPa nitrogen. Thus, repetitive exposures to nitrogen narcosis produced a sensitization of postsynaptic NMDA receptors on DA cells, related to a decreased glutamatergic input in SNc. Consequently, successive nitrogen narcosis exposures disrupted ion-channel receptor activity revealing a persistent nitrogen-induced neurochemical change underlying the pathologic process.

Iatrogenic cerebral air embolism: importance of an early hyperbaric oxygenation.

OBJECTIVES: To assess the relationship between the time period before hyperbaric oxygenation therapy (HBO) and clinical outcome in patients with iatrogenic cerebral air embolism. DESIGN AND SETTING: Retrospective study in a hyperbaric chamber and medical intensive care unit of a university hospital. PATIENTS: All patients with air embolism from 1980 to 1999. INTERVENTIONS: We retrieved the cases of 86 patients who benefited from an identical HBO and analyzed the relationship between the time period before HBO and clinical outcome. RESULTS: Patients treated with HBO less than 6 h had a better outcome than those treated later. In patients treated within this delay the cause was venous air embolism in 84% and arterial air embolism in only 16% of cases. After this delay the cause was venous air embolism (53%) and arterial air embolism (47%). Patients with venous air embolism and recovery had a shorter delay than patients with sequelae or death (2 h 15 min vs. 4 h). Patients with venous air embolism treated less than 6 h had a better outcome than those treated later. In patients with arterial air embolism the time period before HBO was longer than in venous air embolism (8 h vs. 3 h) and the outcome worse (recovery in 35% vs. 67%). In patients with arterial air embolism no difference in the time period was found between patients with recovery and sequelae or death. CONCLUSIONS: We stress the beneficial effect of an early HBO in air embolism, the importance of an increased awareness of physicians concerned with this severe complication, and the need to develop techniques to detect air emboli in the cerebral circulation.

Left-sided superior vena cava: diagnosis by magnetic resonance imaging.

We describe a case of left-sided superior vena cava. The diagnosis was suggested by chest radiograph after central venous catheter placement. This was subsequently confirmed by magnetic resonance imaging.

Gallbladder abnormalities in medical ICU patients: an ultrasonographic study.

Patients in the intensive care unit (ICU) have many risks factors for gallbladder stasis or acute acalculous cholecystitis (ACC), including fasting, total parenteral nutrition, sedation, mechanical ventilation, infection and shock. We have performed a prospective study to estimate the prevalence of ultrasonographic gallbladder abnormalities in 30 consecutive medical ICU patients during the first 2 days of their stay in the ICU. Two patients had previously undergone cholecystectomy and were excluded from the study. Seventeen (61%) of the remaining 28 patients presented with gallbladder abnormalities. Considering three major criteria of ACC, 14 patients (50%) presented with either sludge (25%), wall thickening (22%) or hydrops (11%). However, none of the patients needed a surgical procedure during the study because of gallbladder disease. We conclude that an important proportion of ICU patients presented with gallbladder abnormalities shown by ultrasonography and that this may have implications for establishing a diagnosis of ACC using ultrasonographic criteria.

Echocardiography on HIV patients admitted to the ICU.

A prospective echocardiographic study was conducted in 68 patients with the human immunodeficiency virus (HIV) admitted to the intensive care unit (ICU) (C3 stage 78%, i.v. drug abuse 71%) in order, firstly to, assess the prevalence of cardiac abnormalities, and, secondly, to make an early therapeutic decision. Only five patients presented clinical evidence of cardiac disease. Echocardiographic abnormalities were identified in 35 patients (51%): pericardial effusion: 20 cases (29%), with tamponade in 2 cases that led to an immediate pericardiocentesis. Left ventricular dysfunction: 15 cases (22%) requiring treatment of cardiac failure. Mitral bioprosthesis rupture in 1 patient that led to a surgical procedure. Vegetations of the tricuspid value in 3 drug addicts (4%) requiring early antibiotic treatment. Echocardiography proved to be very helpful in detecting hidden cardiac dysfunctions. It is immensely valuable in ICU management of HIV patients, since prompt initiation of appropriate treatment is essential.

[Prognosis in iatrogenic gas embolism]. / La prognosi delle embolie gassose iatrogene.

Prognosis of iatrogenic air embolism is various according to previous studies. The purpose of this study was to determine the risks factors associated with the prognosis of iatrogenic air embolism. We conducted a retrospective analysis of 113 patients treated with HBO therapy in our hyperbaric center from 1979 to 1993. Initial symptomatology consisted in neurological disorders (71% of cases), respiratory disorders (43% of cases) and hemodynamic disorders (33% of cases). When neurological disorders were observed, HBO therapy included immediate compression to 6 atm abs for 10 to 15 mn with air followed by decompression to 2 atm abs where the patients received 100% oxygen during 1 hour. When no neurological disorders was observed, HBO therapy consisted in an oxygenation for 1 h, 2 atm abs, FiO2 = 1. Overall outcome was: recovery: 69 per cent of cases, sequelae: 26 per cent of cases, death: 5 per cent of cases. Prognosis was very different according to etiologies and existence of neurological disorders. Venous emboli had a better improvement than arterial emboli. In conclusion, patterns of air embolism can be divided clinically into two major categories, cerebral and pulmonary air embolism, which should be individualised in clinical studies. The studies must also individualised etiologies.

Activation of coagulation in decompression illness.

In animal studies, many authors have observed coagulation activation in decompression illness (DCI). These hemostasis modifications have been attributed to circulating bubbles. We have studied molecular hemostasis markers in 25 consecutive divers, victims of DCI admitted to our hyperbaric center, and in 15 control divers. There was no significant difference in parameters studied in the patients and the control group (platelet, fibrinogen, antithrombin III, Thrombin Antithrombin III complexes, and D-Dimers). An activation of coagulation (D-Dimer > 500 ng.ml-1) was noted in three divers with neurologic troubles. However, such signs of coagulation activation were not correlated with the risk of sequeals. No control or study patient with an osteoarticular or vestibular accident presented signs of coagulation activation. Thus, there does not seem to be a correlation between the severity of the accident and the level of coagulation activation. Further studies will be necessary to evaluate the responsibility of hemostasis modifications in the physiopathology of decompression accidents in sports divers.

Neurologic decompression illness: a gravity score.

Treatment of neurologic decompression accidents consists of various hyperbaric oxygen (HBO) protocols. To facilitate such comparisons between different protocols we developed a gravity score. A group of 96 divers was used to establish the score. On admission we first identified signs and symptoms that had possible predictive value (chi 2 test). The parameters included were repetitive dive, clinical course before HBO, objective sensory disorder, motor impairment, and urinary disturbances. Each parameter was assigned a coefficient. The sum of the coefficients for each accident, based on the most severe manifestations before decompression therapy, yielded a score for each diver. A multivariate analysis was used to evaluate the overall agreement between the model prediction and clinical observations, which was 78.7%. A second group (66 divers) was used to validate the score; this group showed a significant difference in the gravity score between the divers who had sequelae and those who did not (P = 0.0001), and between the divers who had incapacitating sequelae and those who had mild sequelae (P = 0.04). Eighty-six percent of the divers with a score above 7 developed sequelae. This index remains to be validated in a prospective multicenter study. If endorsed, valid comparisons can be made between the different therapeutic protocols.

Circulating bubbles and breath-hold underwater fishing divers: a two-dimensional echocardiography and continuous wave Doppler study.

Since the 1960s, decompression illness after breath-hold diving has been widely debated. The aim of this study was to detect circulating bubbles after breath-hold diving in underwater fishing divers. We used continuous Doppler (DUG, COMEX Pro) and transthoracic two-dimensional (2D) echocardiography (Kontron Sigma 1). This study was conducted during a training course organized by the French Federation of Subaquatic Sports at Minorca (Balearic Islands). Ten breath-hold divers performed repeated breath-hold dives for periods ranging from 2 to 6 h [mean maximum depth 35 meters of seawater (msw)]. A dive computer (Maestro Pro Beuchat, analyst PC interface) was used to record diving patterns. No circulating bubbles were detected in the right heart cavities (2D echocardiography) or in the pulmonary artery (continuous Doppler). However, this study had some limits: only 10 subjects were studied and the earliest detection was 3 min after immersion, further studies will thus be required.

[Non-malignant esophagotracheal fistulas in adults. Experience with 35 cases]. / Les fistules oeso-trachéales non malignes de l'adulte. Expérience de trente-cinq cas.

Esophagotracheal fistula always constitutes a serious, life-threatening complication. Fistulae occurring during medical intensive care with mechanical ventilation are currently the most frequent. Their diagnosis was strongly suspected by clinical examination of the patient, but was always confirmed by endoscopy which revealed their exact site in relation to the vocal cords or carina, essential information for the choice of incision when it is decided to perform surgery. Twenty-five patients were treated medically. Treatment was always combined with gastrointestinal resting, control of gastro-oesophageal reflux and broad-spectrum systemic antibiotics. There were 19 deaths and 6 fistulae closed spontaneously. Three of these 6 patients developed a secondary tracheal stenosis, 2 of which were treated surgically by resection-anastomosis. Ten fistulae were closed surgically with a good long-term result. The indication for surgery was essentially based on the patients general and infectious status and on his or her respiratory autonomy. Technically, we always combined direct suture of the two organs with interposition of muscular or pleural tissue.

[Intra-alveolar hemorrhage. An uncommon accident in a breath holding diver]. / Hémorragie intra-alvéolaire. Un accident inhabituel chez un plongeur en apnée.

To date, pulmonary oedema in breath hold divers has only been reported after dives below 50 meters, hypoxaemic syncope being the most common risk. We recently observed a 35-year-old well-trained breath hold diver who was unable to achieve deep inspiration during a high-level competition. After two hours of repeated dives to a depth of 25 meters for approximately 2-minute periods with intermittent recovery the patient developed cough and haemoptysis. The chest X-ray revealed lung images suggestive of intra-alveolar haemorrhage. The patient had taken 1 g of aspirin per os for three days prior to diving. Symptoms subsided spontaneously in 48 hours and one month later all haematology tests were normal except for minimal alteration of platelet aggregation. Pulmonary oedema in breath hold divers is usually attributed to blood shift to the pulmonary circulation related to the lowered intra-thoracic pressure. In our case, oedema was secondary to intra-alveolar haemorrhage favoured by aspirin which should be avoided before breath hold diving.

[Treatment of nosocomial pneumopathies caused by Pseudomonas aeruginosa with ceftazidime. 50 cases in pulmonary resuscitation]. / Traitement des pneumopathies nosocomiales à Pseudomonas aeruginosa par la ceftazidime. Cinquante observations en réanimation pneumologique.

Fifty patients under prolonged mechanical ventilation who developed nosocomial lung infections caused by Pseudomonas aeruginosa were treated with ceftazidime. This cephalosporin was used alone in 18 cases and combined with another antibiotic (usually an aminoglycoside) in 32 cases. Favourable results were obtained in 40 cases, with regression of the clinical signs and eradication of the organism between the 5th and 10th days of treatment. Eight of the 10 failures occurred in patients with impaired ventilation due to chronic obstructive lung disease. Secondary superinfection was observed in 12 cases. Among the 257 strains of P. aeruginosa isolated in our respiratory intensive care unit over an 18-month period, 88 per cent were sensitive to ceftazidime, and this figure remained stable after the period when ceftazidime was given. These in vitro findings probably account for the remarkable results obtained in infections which up to now had mortality rates of 30 to 60 per cent, depending on the patient's underlaying condition.

[Antibiotherapy in gangrene of the perineum]. / L'antibiothérapie dans les gangrènes du périnée.

Fifty cases of extensive and necrotizing perineal cellulitis ("perineal gangrene") are reported. The disease, remarkable for its many anatomical and bacteriological varieties, is regarded as a therapeutic requiring multidisciplinary management. Bacteriological samples were polymicrobial in 40 cases. Streptococcus D and aerobic Gram-negative bacilli were isolated in 21 patients. The initial antibiotic treatment had to be modified on ten occasions in 36 patients who were given penicillin G in high doses and on five occasions in 14 patients who received a beta-lactam antibiotic active against anaerobes. Nineteen patients (38 p. 100) died; death was directly related to the sepsis in 16 cases. The death rate was the same in the two treatment groups (11/36 and 5/14) and similar to that found in the literature. The authors advocate an ureidopenicillin, fosfomycin and imidazole combination as a substitute for the conventional penicillin G, aminoglycoside, imidazole combination, since the former is active against Streptococcus D and has better tissue penetration.

[Severe air embolism after surgical irrigation with hydrogen peroxide]. / Embolie gazeuse grave après une irrigation chirurgicale à l'eau oxygénée.

BACKGROUND: Hydrogen peroxide is widely used for its antiseptic properties. In certain circumstances, however the risk of air embolism can create a life-threatening situation. CASE REPORT: A 16-year-old adolescent required surgical treatment for femorotibial trauma. During the surgical procedure, cardiac arrest suddenly occurred when hydrogen peroxide was being used to irrigate the wound. A central catheter was inserted and aspiration of air bubbles in the line led to the diagnosis of air embolism. Outcome was unfavorable despite successful resuscitation. A chronic neurovegatative state ensued and the patient died 8 months later. DISCUSSION: Several cases of air embolism have been described due to hydrogen peroxide in surgical, medical and accidental circumstances. Our case emphasizes the potential danger of using hydrogen peroxide in certain situations, including orthopedic surgery. Clinicians should be aware that hydrogen peroxide is not a perfectly safe product.

[Fat embolism after intrapenile injection of sweet almond oil]. / Embolie graisseuse après injection intrapénienne d'huile d'amande douce.

We report a case of fat embolism following self injection of vegetable oil in the penis, to treat an impotence. The patient developed respiratory failure and neurological disorders as confusion. A chest roentgenogram revealed diffuse alveolar infiltrate. Initially, he presented an hemoconcentration, and fat globules in his urine. The outcome was favourable in 72 hours, with oxygen and hydration. The diagnosis of fat embolism was made after neurological improvement: the patient admitted to injection his penis with vegetable oil, in his corpus cavernosum.

[Significance of systematic endoscopic decannulation. Retrospective study on intensive care patients]. / Intérêt de la fibroscopie systématique de décanulation. Etude rétrospective portant sur des malades de réanimation.

We performed a retrospective study in 42 consecutive tracheotomy patients hospitalized in an intensive care unit. Endoscopy was used systematically to assess all patients at decanulation and whenever symptoms suggested possible tracheal granuloma. Nine tracheal granulomas were evidenced. There was no significant association between presence of a granuloma and patient status: age, underlying chronic respiratory failure, or tracheobronchial infection. In initial stages, tracheal granulomas usually have little clinical expression. Difficulty in weaning from ventilatory assistance is generally the main sign. The long-term course after decanulation can progress to major respiratory disorders due to tracheal stenosis. We emphasize the importance of systematic endoscopy at decanulation to recognize existing granulomas early when local treatment remains simple (usually laser vaporization).