Effects of propofol vs sevoflurane on arterial oxygenation during one-lung ventilation.

BACKGROUND: The inhibitory effect of anaesthetic agents on hypoxic pulmonary vasoconstriction may depend upon their dose, especially when using a volatile agent. The aim of this randomized open study was to compare the effects of sevoflurane and propofol, as primary anaesthetic agents, on oxygenation during one-lung ventilation (OLV), with their administration being adjusted to maintain bispectral index (BIS) values between 40 and 60. METHODS: Eighty patients scheduled for a lobectomy, receiving an epidural mixture of ropivacaine and sufentanil, were randomly assigned to Group S (maintenance with sevoflurane) or Group P (maintenance with propofol). After placement of a double-lumen tube, the lungs were ventilated at an inspiratory fraction of oxygen of 1.0, a tidal volume of 6 ml kg(-1), and 12 bpm. Arterial blood gas samples were taken as follows: during two-lung ventilation before OLV, and during the first 40 min of OLV. RESULTS: Fifteen patients were excluded (incorrect placement of the tube or BIS outside the desired range). The two groups were comparable in terms of demographic variables, haemodynamic, and BIS levels during the operation. Four patients in each group had a Sp(O2)<90%. Mean of the lowest Pa(O2) was 16.3 (7.5) kPa in Group S and 17.7 (9.3) kPa in Group P (ns). CONCLUSIONS: Sevoflurane and propofol had similar effect on Pa(O2) during OLV when their administration is titrated to maintain BIS between 40 and 60.

Feasibility of closed-loop titration of propofol guided by the Bispectral Index for general anaesthesia induction: a prospective randomized study.

BACKGROUND: This study was designed to evaluate the feasibility of propofol infusion by a closed-loop system for the titration of anaesthetic induction guided by Bispectral Index. METHODS: Forty patients were prospectively and randomly allocated into two groups: the target control infusion (TCI) group, where propofol titration was performed manually guided by the Bispectral Index using a commercial pharmacokinetic model (Diprifusor device) and the closed-loop group where titration was performed using a proportional differential algorithm. For both groups, the objective was to achieve a Bispectral Index of 50. Remifentanil TCI was infused at a target of 2 ng mL-1 and was maintained constant throughout the study. Feasibility of automatic induction was evaluated with performance error and haemodynamic data. RESULTS: Bispectral Index overshoot (-9 +/- 13% vs. -16 +/- 20%, P = 0.035) and mean duration of induction (381 +/- 106 s vs. 490 +/- 131 s, P = 0.004) were lower in the closed-loop group than in the TCI group. Haemodynamic data were similar between groups with a similar use of ephedrine bolus. CONCLUSION: The system was able to allow induction clinically for all patients. Automated titration guided by Bispectral Index for propofol infusion was feasible without increase in haemodynamic adverse effects.

[A new case of perforation of the esophagus during intraoperative transesophageal echocardiography]. / Nouvelle observation de perforation de l'oesophage lors d'une échocardiographie transoesophagienne peropératoire.

We describe a novel case of peroperative oesophageal perforation following insertion of a transoesophageal echocardiography probe. Histories of left pneumonectomy and oesophageal fragility probably explained this complication. The perforation was stitched and the coronary artery bypass graft surgery was delayed by a few days. Early postoperative period was not marked by infectious complication but the patient could not weaned from ventilatory support. She died 6 months later.

A computed tomographic scan assessment of endotracheal suctioning-induced bronchoconstriction in ventilated sheep.

This study was directed at assessing changes in bronchial cross-sectional surface areas (BCSA) and in respiratory resistance induced by endotracheal suctioning in nine anesthetized sheep. Cardiorespiratory parameters (Swan-Ganz catheter), respiratory resistance (inspiratory occlusion technique), BCSA, and lung aeration (computed tomography) were studied at baseline, during endotracheal suctioning, and after 20 consecutive hyperinflations. Measurements performed initially at an inspired oxygen fraction (FI(O(2))) of 0.3 were repeated at an FI(O(2)) of 1.0. At an FI(O(2)) of 0.3, endotracheal suctioning resulted in atelectasis, a reduction in BCSA of 29 +/- 23% (mean +/- SD), a decrease in arterial oxygen saturation from 95 +/- 3% to 87 +/- 12% (p = 0.02), an increase in venous admixture from 19 +/- 10% to 31 +/- 19% (p = 0. 006), and an increase in lung tissue resistance (DR(rs)) (p = 0. 0003). At an FI(O(2)) of 1.0, despite an extension of atelectasis and an increase in pulmonary shunt from 19 +/- 5% to 36 +/- 2% (p < 0.0001), arterial O(2) desaturation was prevented and BCSA decreased by only 7 +/- 32%. A recruitment maneuver after endotracheal suctioning entirely reversed the suctioning-induced increase in DR(rs) and atelectasis. In three lidocaine-pretreated sheep, the endotracheal suctioning-induced reduction of BCSA was entirely prevented. These data suggest that the endotracheal suctioning-induced decrease in BCSA is related to atelectasis and bronchoconstriction. Both effects can be reversed by hyperoxygenation maneuver before suctioning in combination with recruitment maneuver after suctioning.

Intra-operative direct electrical stimulations of the central nervous system: the Salpêtrière experience with 60 patients.

Indications of surgical treatment for lesions in the central nervous system depend on the risk of a definitive neurological deficit, related to the benefit of resection. Detection of eloquent areas is then necessary because of major individual variability. Neuro-imaging functional techniques are in development and are beginning to be efficient for cortical sensorymotor mapping, but still lack sensitivity and specificity for language mapping, and remain unable to give real-time data during surgery and to perform sub-cortical mapping. The more precise and reliable method of functional mapping is represented by the intra-operative direct electrical stimulations (DES), which allow identification and preservation of essential pathways for motricity, sensibility and language, at each level of the central nervous system (cortico-subcortical). We report our experience of DES in the surgery of tumours and vascular malformations located in supra-tentorial brain eloquent areas, with a consecutive series of 60 patients operated on under general or local anaesthesia, from November 1996 until May 1999 in our department at La Salpêtrière Hospital. Presenting symptoms in the 60 subjects (39 males, 21 females, mean age: 45 years) were seizures in 37 cases with normal clinical examination, and mild neurological deficit in 29 cases. MRI showed 60 supra-tentorial brain lesions: 30 precentral, 12 postcentral, 14 perisylvian in the dominant hemisphere, 4 deep-seated. All subjects underwent surgical resection using DES, with supratentorial cortico-subcortical mapping under general anaesthesia for motor areas detection in 43 cases and under local anaesthesia for sensori-motor and/or language tasks in 17 cases. The final histological diagnosis was 44 gliomas (31 low-grade and 13 high-grade), 9 metastasis, 3 cavernomas, 4 arteriovenous malformations (AVM). Resection was total or subtotal in 52 cases (87%) and partial in 8 cases (13%). 29 patients had no post-operative deficit, while the other 31 patients were impaired post-operatively, with in all cases, except 3, a complete recovery delayed for 15 days to 3 months (overall morbidity: 5%). The median follow up was 14 months. Intra-operative direct electrical stimulations of the central nervous system constitute a reliable, precise and safe method, allowing the realization of a functional mapping useful for all operations of lesions located in eloquent areas. This technique allows a minimization of definitive post-operative neurological deficit, and concurrently an improvement in the quality of resection.

Factors influencing indoor concentrations of nitric oxide in a Parisian intensive care unit.

In low concentrations, inhaled nitric oxide (NO) increases arterial oxygenation in patients with severe acute respiratory distress syndrome. When present in the ambient atmosphere, NO and its oxidative derivate, nitrogen dioxide (NO2), are considered pollutants. The aim of this study was to assess whether the administration of inhaled NO to mechanically ventilated patients was associated with an increased risk of exposure to NO and NO2 for medical and paramedical staff. During a 1-yr period, indoor and outdoor NO and NO2 concentrations were measured using chemiluminescence in a 14-bed intensive care unit (ICU) to assess the possible influence of therapeutic NO administration on indoor pollution. Ambient concentrations of NO within the ICU were 237 +/- 147 parts per billion (ppb) during periods of NO administration and 289 +/- 147 ppb during periods without NO administration (mean +/- SD, NS). Indoor concentrations of NO and NO2 were entirely dependent on outdoor concentrations and were mainly influenced by climatic conditions such as atmospheric pressure, mass of clouds, and speed of the wind. Therapeutic administration of concentrations of inhaled NO < or = 5 ppm to critically ill patients did not affect the ambient concentration of NO and NO2 within the ICU, which was mainly dependent on the outdoor air pollution. As a consequence, scavenging of exhaust NO from the breathing circuit in the ventilator does not appear mandatory in ICUs located in areas with significant urban pollution when NO concentrations < or = 5 ppm are administered.

Factors influencing the tracheal fluctuation of inhaled nitric oxide in patients with acute lung injury.

BACKGROUND: Inhaled nitric oxide (NO) improves arterial oxygenation in patients with acute lung injury (ALI) by selectively dilating pulmonary vessels perfusing ventilated lung areas. It can be hypothesized that NO uptake from the lung decreases with increasing ventilation perfusion mismatch. This study was undertaken to determine the factors influencing the fluctuation of tracheal NO concentration over the respiratory cycle as an index of NO pulmonary uptake in patients with ALI. METHODS: By using a prototype system (Opti-NO) delivering a constant flow of NO only during the inspiratory phase, 3 and 6 ppm of NO were administered during controlled mechanical ventilation into a lung model and to 11 patients with ALI. All patients had a thoracic computed tomography (CT) scan. Based on an analysis of tomographic densities, lungs were divided into three zones: normally aerated (-1.000 to -500 Hounsfield units [HU]), poorly aerated (-500 to -100 HU), and nonaerated (-100 to +100 HU), and the volume of each zone was computed. Concentrations of NO in the inspiratory limb and trachea were continuously measured by a fast-response chemiluminescence apparatus. RESULTS: In the lung model, tracheal NO concentration was stable with minor fluctuation. In contrast, in patients, tracheal NO concentration fluctuated widely during the respiratory cycle (55 +/- 10%). Because uptake of NO from the lungs was absent in the lung model but present in the patients, this fluctuation was considered as an index of pulmonary uptake of NO. This was further substantiated by (1) the coincidence of the peak and minimum tracheal NO concentration with the end-inspiratory and end-expiratory phases, respectively, and (2) continued decrease of tracheal NO concentration during prolonged expiratory phase. In patients with ALI, the fluctuation of tracheal NO concentration expressed as the difference between inspiratory and expiratory NO concentrations divided by inspiratory NO concentration was greater at 6 ppm than at 3 ppm (P < 0.01), was linearly correlated with normally aerated lung volume, inversely correlated with alveolar dead space and with poorly aerated lung volume. CONCLUSION: In patients with ALI, fluctuation of tracheal NO concentration over the respiratory cycle can be considered as an index of NO uptake from the lungs that depends on aerated lung volume and perfusion of ventilated lung areas. At bedside, it may be used to follow the evolution of ventilation-perfusion mismatch.

Distribution of inhaled nitric oxide during sequential and continuous administration into the inspiratory limb of the ventilator.

OBJECTIVES: The concentrations of nitric oxide (NO) in the ventilatory circuits and the patient's airways were compared between sequential (SQA) and continuous (CTA) administration during inspiratory limb delivery. DESIGN: Prospective controlled study. SETTING: 14-bed Surgical Intensive Care Unit of a teaching University hospital. PATIENTS AND PARTICIPANTS: Eleven patients with acute lung injury on mechanical ventilation and two healthy volunteers. INTERVENTIONS: A prototype NO delivery device (Opti-NO) and César ventilator were set up in order to deliver 1, 3 and 6 parts per million (ppm) of NO into the bellows of a lung model in SQA and CTA. Using identical ventilatory and Opti-NO settings, NO was administered to the patients with acute lung injury. MEASUREMENTS AND RESULTS: NO concentrations measured from the inspiratory limb [INSP-NOMeas] and the trachea [TRACH-NOMeas] using fast response chemiluminescence were compared between the lung model and the patients using controlled mechanical ventilation with a constant inspiratory flow. INSP-NOMeas were stable during SQA and fluctuated widely during CTA (fluctuation at 6 ppm = 61% in the lung model and 58 +/- 3% in patients). In patients, [TRACH-NOMeas] fluctuated widely during both modes (fluctuation at 6 ppm = 55 +/- 3% during SQA and 54 +/- 5% during CTA). The NO flow requirement was significantly lower during SQA than during CTA (74 +/- 0.5 vs 158 +/- 2.2 ml.min-1 to attain 6 ppm, p = 0.0001). INSP-NOMeas were close to the values predicted using a classical formula only during SQA (bias = -0.1 ppm, precision = +/-1 ppm during SQA; bias = 2.93 ppm and precision = +/-3.54 ppm during CTA). During SQA, INSP-NOMeas varied widely in healthy volunteers on pressure support ventilation. CONCLUSIONS: CTA did not provide homogenous mixing of NO with the tidal volume and resulted in fluctuating INSP-NOMeas. In contrast, SQA delivered stable and predictable NO concentrations during controlled mechanical ventilation with a constant inspiratory flow and was economical compared to CTA. However, SQA did not provide stable and predictable NO concentrations during pressure support ventilation.

Dose-response curves of inhaled nitric oxide with and without intravenous almitrine in nitric oxide-responding patients with acute respiratory distress syndrome.

BACKGROUND: Inhaled nitric oxide, a selective pulmonary vasodilator, in combination with intravenous almitrine, a selective pulmonary vasoconstrictor, markedly improves arterial oxygenation in 50-60% of patients with acute lung injury. The goal of this study was to assess dose response of inhaled nitric oxide with and without almitrine in patients with acute respiratory distress syndrome responding to nitric oxide. METHODS: Six critically ill patients (aged 44 +/- 7 yr) were studied during early stage of their acute respiratory failure (Murray score: 2.6 +/- 0.1). All responded to 15 parts per million (ppm) of inhaled nitric oxide by an increase in Pao2 of at least 40 mmHg at FIo2 1. Hemodynamic and respiratory parameters were recorded continuously from pulmonary artery and systemic catheters. Inspiratory, expiratory, and mean intratracheal nitric oxide concentrations were monitored continuously using a fast response time chemiluminescence apparatus (NOX 4000, Sérès, Aix-en-provence, France). On day 1, 6 inspiratory concentrations of nitric oxide were randomly administered: 0.15, 0.45, 1.5, 4.5, 15, and 45 ppm to determine the dose response of inhaled nitric oxide on Pao2, pulmonary shunt, mean pulmonary artery pressure, and pulmonary vascular resistance index. On day 2, a continuous intravenous infusion of almitrine at a dose of 16 micrograms.kg-1.min-1 was administered and dose response to inhaled nitrix oxide was repeated according to the same protocol as during day 1. A constant FIo2 of 0.85 was used throughout the study. RESULTS: Nitric oxide induced a dose-dependent increase in Pao2 for inspiratory nitric oxide concentrations ranging between 0.15 and 1.5 ppm. Almitrine increased Pao2/FIo2 from 161 +/- 30 to 251 +/- 45 mmHg (P < 0.001) and pulmonary vascular resistance index from 455 +/- 185 to 527 +/- 176 dyn.s.cm-5.m2 (P < 0.05), and decreased pulmonary shunt (Qs/QT) from 35 +/- 2 to 33 +/- 3% (P < 0.001). During almitrine combined with nitric oxide, a dose-dependent increase in Pao2 was observed for inspiratory nitric oxide concentrations ranging between 0.15 and 1.5 ppm. Almitrine plus nitric oxide 1.5 ppm increased Pao2/FIo2 from 161 +/- 30 to 355 +/- 36 mmHg (P < 0.001), decreased Qs/QT from 35 +/- 2 to 24 +/- 2% (P < 0.001), pulmonary vascular resistance index from 455 +/- 185 to 385 +/- 138 dyn.s.cm-5.m2 (P < 0.05), and mean pulmonary artery pressure from 31 +/- 4 to 28 +/- 4 mmHg (P < 0.001). CONCLUSIONS: In 6 patients with early acute respiratory distress syndrome and highly responsive to inhaled nitrix oxide, the administration of intravenous almitrine at a concentration of 16 micrograms.kg-1.min-1 induced an additional increase in Pao2. Dose response of nitric oxide was not changed by the administration of almitrine and a plateau effect was observed at inspiratory nitric oxide concentrations of 1.5 ppm.

Factors influencing cardiopulmonary effects of inhaled nitric oxide in acute respiratory failure.

The aim of this prospective study was to determine factors influencing effects of inhaled nitric oxide (NO) on the pulmonary circulation and on gas exchange in critically ill patients with acute lung injury. Twenty-one hypoxemic patients with acute respiratory failure (PaO2 = 127 +/- 69 mm Hg during intermittent positive pressure ventilation, FiO2 = 1), were mechanically ventilated with 2 ppm NO and pure oxygen. The effect of positive end-expiratory pressure (PEEP) on alveolar recruitment was assessed on an anatomic basis using a high-resolution and spiral thoracic computed tomographic (CT) scan. Four conditions were studied in random order: zero end-expiratory pressure (ZEEP), ZEEP + 2 ppm NO, 10 cm H2O PEEP, 10 cm H2O PEEP + 2 ppm NO. During ZEEP and PEEP, NO significantly decreased pulmonary vascular resistance index (PVRI), mean pulmonary arterial pressure (MPAP), true pulmonary shunt (Qs/QT), and alveolar dead space (VDA/VT) and significantly increased PaO2 (p < 0.01). During ZEEP, NO-induced decreases in PVRI (delta PVRI) and MPAP (delta MPAP) were significantly correlated to baseline PVRI and MPAP (delta PVRI = -0.5 PVRI + 125, r = 0.97, p < 0.01 and delta MPAP = -0.28 MPAP + 4.8, r = 0.69, p < 0.05). These changes were not potentiated by PEEP-induced alveolar recruitment. The NO-induced increase in PaO2 (delta PaO2) was not significantly correlated with baseline PaO2 but was correlated with baseline PVRI (delta PaO2 = 0.11 PVRI + 30, r = 0.67, p < 0.05). In patients in whom PEEP was associated with alveolar recruitment, NO increased PaO2 by 66 +/- 24 mm Hg during ZEEP and by 104 +/- 26 mm Hg during PEEP (p < 0.01). In patients in whom PEEP did not induce alveolar recruitment, the NO-induced increase in PaO2 was similar during ZEEP and PEEP conditions (+70 +/- 15 mm Hg versus +76 +/- 12 mm Hg, NS). In patients with adult respiratory distress syndrome, factors determining NO-induced improvement in arterial oxygenation and pulmonary vascular effects are PEEP-induced alveolar recruitment and the baseline level of pulmonary vascular resistance.

[Seroepidemiological study of human leptospirosis at Reunion Island]. / Etude sero épidémiologique de la leptospirose humaine à l'île de laRéunion.

In order to evaluate the prevalence of human leptospirosis in Reunion island and to identify possible risk factors, a study was realised on a representative population sample of 3.338 persons. The prevalence of leptospirosis, diagnosed by ELISA and confirmed by Micro Agglutination Test, was 1.1%. Male predominance and higher prevalence in rainy parts of the island, were confirmed. It has not been possible to display risk factors such as housing conditions or professional exercise. The serological repartition showed not only icterohaemorrhagiae serovar, but also canicola, panama and sejroe, especially in women. These results, compared with clinical studies (showing nearly exclusive male repartition, in agricultural workers, due to icterohaemorrhagiae serovar), confirm the double look of human leptospirosis in Reunion island: clinical leptospirosis, severe, concerning males, often countrymen, due to icterohaemorrhagiae serovar, and infraclinical leptospirosis, concerning principally females, which is a domestic illness, due to other serovars.

[Human leptospirosis in Reunion Island. A 3-year epidemiological study (1985-1987)]. / La leptospirose humaine à la Réunion. Etude épidémiologique sur trois années (1985-1987).

During a three-year period (1985-1987), in Reunion Island, 252 cases of leptospirosis were clinically diagnosed in humans, and serologically confirmed. The epidemiological study showed a significant male predominance, presence during all ages of life; no month and no geographical zone are spared but maximal incidences are noted during periods of and in localities with the most important rainfall. Severe forms are frequent but mortality remains low.