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Biomedical subjects

A M Cros

Publications and source records attributed to A M Cros.

At least 19 recordsLinked to original sources
PubMed2006

Pressure support ventilation during fibreoptic intubation under propofol anaesthesia.

GOAL OF THE STUDY: To assess the benefit of pressure support ventilation during fibreoptic intubation performed under propofol anaesthesia in patients having an anticipated difficult intubation. PROCEDURES: Thirty-two patients with ENT cancer, and having at least two criteria for anticipated difficult intubation were prospectively included. All patients received topical lidocaine 2% and propofol by plasma target control infusion (initial target concentration 3 microg ml(-1), then adjusted to maintain loss of consciousness without apnoea). They were randomly assigned between two groups: spontaneous breathing (SB) or pressure support ventilation (with a support level set at 10 cm H(2)O) both using Fi(o(2))=1. Conditions for fibreoptic intubation, respiratory parameters (pulse oxymetry, ventilatory frequency, tidal volume and PetCO2 after intubation) and haemodynamic parameters were recorded. RESULTS: Patient characteristic data and intubation conditions were similar between both groups. All patients had a successful fibreoptic intubation and none needed a rescue procedure because of desaturation. In spite of a longer duration of intubation, PE'CO2 after intubation was lower and tidal volume during intubation was higher with pressure support ventilation than in SB patients [38.1 (4.2) vs 42.3 (4.7) mm Hg and 371 (139) vs 165 (98) ml, respectively]. Desaturation episodes were observed in two SB patients conversely to no episode during pressure support ventilation, probably because of the higher minute ventilation. CONCLUSION: Pressure support represents a useful method to improve ventilation during fibreoptic intubation under propofol anaesthesia in patients with an anticipated difficult intubation.

Aged↗
PubMed2006

Pressure-controlled ventilation is superior to volume-controlled ventilation with a laryngeal mask airway in children.

BACKGROUND: This prospective, randomized, crossover study had two purposes: first, to determine whether pressure-controlled ventilation (PCV) is safer than volume-controlled ventilation (VCV) by preventing gastric insufflation in children ventilated through an laryngeal mask airway (LMA); second, to assess whether the measurement of LMA leak pressure (P(leak)) is useful for preventing leakage during positive pressure ventilation (PPV). METHODS: Forty-one, 2 to 15-year-old children underwent general anesthesia with an LMA. The expiratory valve was set at 30 cmH(2)O and P(leak) was measured using constant gas flow. Children were randomly ventilated using PCV or VCV for 5 min in order to reach a P(ET)CO(2) not exceeding 45 mm Hg, and then they were ventilated with the alternative mode. If the target P(ET)CO(2) could not be obtained in one mode, we switched to the other. If both modes failed, children were intubated. Tidal volumes, P(ET)CO(2) and airway pressures were noted and compared between modes. Gastric insufflation was checked by epigastric auscultation. RESULTS: PCV provided more efficient ventilation than VCV, as targeted P(ET)CO(2) was obtained without gastric insufflation using PCV in all cases except one, whereas VCV failed in three cases. No gastric insufflation occurred when ventilating below peak. CONCLUSIONS: These findings suggest that in the age group studied, PCV is more efficient than VCV for controlled ventilation with a laryngeal mask. Gastric insufflation did not occur with this mode.

Adolescent↗
PubMed2005

[Clinical evaluation of the single use Laryngeal Tube in adults: the LTD].

OBJECTIVES: The Laryngeal Tube (LT) is a supra-laryngeal device indicated to manage upper airway during anaesthesia. Leak pressures were lately reported higher for the LT as compared to the LMA. A recent study found a small amount of proteinaceous material on LMA after classical sterilization suggesting a risk of contamination by unconventional transmissible agents (prions). The aim of this study was to evaluate the effectiveness of the single use Laryngeal Tube: the LTD. STUDY DESIGN: Prospective study realized after ethical committee agreement and patient consent for participation. PATIENTS AND METHODS: Adults, ASA score< or =3, 18 to 75-year-old, without upper airway abnormality or difficult intubation criteria, anaesthesia< or =2 h, free access to patient's head and LTD. The following criteria were evaluated: easiness of insertion, assisted (AV), controlled (CV) and spontaneous ventilation (SV); leak pressure (LP) 5 and 15 min after insertion; complications during anaesthesia conducted with propofol and remifentanil under bispectral index monitoring. RESULTS: 55 patients were included; only one failure was reported at insertion. AV and CV were easy, SV difficult in 4 patients with chin lift necessary for adequate ventilation. LP was 28.92+/-8.4 and 30.87+/-8.68 cmH2O 5 and 15 min after insertion respectively. No major incident was noticed throughout the study. CONCLUSION: the use of the LTD was easy and successful. Moreover the LTD totally excluded the risk of contamination by unconventional transmissible agents.

Adult↗
PubMed2005

Concentration of remifentanil needed for tracheal intubation with sevoflurane at 1 MAC in adult patients.

BACKGROUND AND OBJECTIVE: Inhalation induction with sevoflurane provides acceptable conditions for tracheal intubation. Opioids significantly decrease the alveolar concentration needed to achieve tracheal intubation. The purpose of this study was to determine the target concentration of remifentanil providing excellent conditions for tracheal intubation with sevoflurane at 1 minimum alveolar concentration without muscle relaxant. METHODS: Twenty-four consecutive patients, aged 18-50 yr, ASA I or II, were studied. Induction of anaesthesia was performed with sevoflurane at age-adjusted minimum alveolar concentration. Remifentanil was simultaneously administered using target-controlled infusion with the Minto model. Target plasma concentration of remifentanil was selected for each patient according to an up-and-down method. RESULTS: The mean target concentration of remifentanil for successful tracheal intubation was 3.3 ng mL(-1) (95% confidence interval: 2.6-3.9 ng mL(-1)). Arterial pressure, heart rate and bispectral index did not increase after tracheal intubation in the group of patients with successful intubation. CONCLUSIONS: Remifentanil at 3.3 ng mL(-1) together with sevoflurane at 1 minimum alveolar concentration provides excellent conditions for tracheal intubation in 50% of patients.

Adolescent↗
PubMed2004

[Inhalation induction].

OBJECTIVES: To clarify how pharmacokinetics explains the speed and quality of mask induction with sevoflurane alone or associated with adjuvants. To describe the various techniques to obtain adequate anaesthesia for laryngeal mask or tracheal tube insertion. To give the indications, contra-indications and complications of this technique. DATA SOURCES: Data were obtained from Medline and authors clinical experience. DATA SYNTHESIS: Inhalation induction in adults affords rapid loss of consciousness similar to the intravenous route if high concentrations of sevoflurane are delivered to the patient. Time of laryngeal mask or tracheal tube insertion is longer but may be reduced by adding N(2)O and/or a low opioid dose. The interest of benzodiazepine as premedication is not established but is highly probable when considering its potentiating effect on halogenated agents. Without any adjuvant, inhalation induction maintains spontaneous ventilation better than propofol. This justifies favouring this technique when difficult intubation is anticipated. This technique is associated to less or similar cardiovascular effects than intravenous propofol. However, some patients exhibit dramatic tachycardia and arterial pressure increase that should lead to caution in cardiovascular disabled patients. This sympathetic hyperactivity occurs with epileptiform EEG activity that was never associated with postanaesthesia mental dysfunction. In aged or cardiac patients, by reducing sevoflurane concentrations from 8% to 2% (or by 2% decreasing steps), the cardiovascular effect of this inhalation induction is better than propofol. This technique is contra-indicated in HMS susceptible patients and those suffering from a myopathy, or patients with intracranial hypertension, a full stomach or active gastro-oesophageal reflux. CONCLUSION: Inhalation induction in adults remains little used in common clinical practice. Technical improvement by adding opioids and education of anesthetists should increase the diffusion of this alternative method to intravenous induction of anaesthesia.

Anesthesia, Inhalation↗
PubMed2003

[High frequency jet ventilation in paediatric anaesthesia].

High frequency jet ventilation (HFJV) is an alternative ventilatory mode during anaesthesia for laryngeal microsurgery. This procedure ensures good visualization of the operating field but is not without risk. Thus, its use in paediatric patients requires sound knowledge of respiratory physiology of children and infants. In children up to 8 years, the jet ventilator adjustments must take into account the lower pulmonary compliance and the higher airway resistance (time-constant). In order to avoid barotrauma, which is the main HFJV complication, the jet ventilator has to include a monitoring airway pressure system. The driving pressure and the frequency must be gradually increased while checking thoracic expansion. Total intravenous anaesthesia with profound muscular relaxation using a thin transglottic catheter is the most commonly used technique. Standard monitoring of anaesthesia does not preclude strict clinical supervision so as to detect any pulmonary distension. The air-oxygen mixture must be adjusted to provide the lowest FIO2 possible (< or = 30%) when using the CO2 laser. The main indications for the use of HFJV in paediatric laryngeal microsurgery are laryngomalcia, laryngeal papillomatosis and subglottic haemangioma. HFJV is a reliable and useful technique in airway paediatric surgery providing the operator has good knowledge of the physiological particularities in children.

Anesthesia↗
PubMed2002

[Anesthesia induction with sevoflurane in adult patients with predictive signs of difficult intubation].

OBJECTIVE: This work was carried out to study induction with sevoflurane in adult patients with predictive signs of difficult intubation. STUDY DESIGN: Randomised prospective study. PATIENTS AND METHODS: The study had two parts. Part I: 15 patients without predictive signs of difficult intubation but with a cervical collar. Eight patients were anaesthetised with propofol 3 mg.kg-1 and fentanyl 2 micrograms.kg-1, seven with sevoflurane 8%. Part II: 20 patients with predictive signs of difficult intubation anaesthetised with sevoflurane 8%. RESULTS: In part I, all patients were intubated, the time for intubation was longer with sevoflurane, 6 vs 4 min. They were apneic only in the propofol group. After intubation, 7 cases of coughing (4 severe) occurred in the propofol group and 3 moderate coughing in the sevoflurane group. In part II, one patient experienced considerable agitation after oral airway insertion and was excluded. Other patients were intubated with sevoflurane. Seven patients were intubated with a bougie, three patients through an intubating LMA and one patient with a rigid bronchoscope. The other patients were intubated with a Macintosh blade. The mean time for intubation was 10 +/- 7 min and end tidal sevoflurane concentration after intubation was 4 +/- 0.6%. After intubation, 7 cases of coughing (3 severe) occurred but no desaturation < 95%. No significant haemodynamic variations occurred. CONCLUSION: Induction with sevoflurane 8% allowed tracheal intubation without major incidents. All patients breathed spontaneously. Sevoflurane can be recommended for induction in cases of predictive difficult intubation.

Adult↗
PubMed2001

Comparison of the intubating laryngeal mask airway with the fiberoptic intubation in anticipated difficult airway management.

BACKGROUND: The intubating laryngeal mask airway (ILMA; Fastrach; Laryngeal Mask Company, Henley-on-Thames, UK) may provide an alternative technique to fiberoptic intubation (FIB) to facilitate the management of the anticipated difficult airway. The authors therefore compared the effectiveness of the ILMA with FIB in patients with anticipated difficult intubation. METHODS: One hundred patients, with at least one difficult intubation criteria (Mallampati class III or IV, thyromental distance < 65 mm, interincisor distance < 35 mm) were enrolled (FIB group, n = 49; ILMA group, n = 51) in this prospective randomized study. Anesthesia was induced with propofol and maintained with alfentanil and propofol after an efficient mask ventilation has been demonstrated. The success of the technique (within three attempts), the number of attempts, duration of the successful attempt, and adverse events (oxygen saturation < 90%, bleeding) were recorded. RESULTS: The rate of successful tracheal intubation with ILMA was 94% and comparable with FIB (92%). The number of attempts and the time to succeed were not significantly different between groups. In case of failure of the first technique, the alternative technique always succeeded. Failures in FIB group were related to oxygen desaturation (oxygen saturation < 90%) and bleeding, and to previous cervical radiotherapy in the ILMA group. Adverse events occurred significantly more frequently in FIB group than in ILMA group (18 vs. 0%, P < 0.05). CONCLUSION: The authors obtained a high success rate and comparable duration of tracheal intubation with ILMA and FIB techniques. In patients with previous cervical radiotherapy, the use of ILMA cannot be recommended. Nevertheless, the use of the ILMA was associated with fewer adverse events.

Adult↗
PubMed2000

Determination of sevoflurane alveolar concentration for tracheal intubation with remifentanil, and no muscle relaxant.

The sevoflurane alveolar concentration needed for tracheal intubation with remifentanil was studied in 26 adult patients premedicated with 100 mg hydroxyzine. Anaesthesia was induced with sevoflurane in oxygen. The concentration was determined by Dixon's up-and-down method. The first patient was tested at 4.5%. One minute after obtaining the preselected value, remifentanil 1 microg.kg-1 was injected for 60 s followed by an infusion of 0.25 microg.kg-1. min-1. Ventilation was then manually assisted for 2 min and tracheal intubation was attempted. Tracheal intubation conditions and responses to intubation were noted. Heart rate and mean arterial pressure were recorded before induction, before remifentanil injection, and before and 3 min after tracheal intubation. The concentration for acceptable intubating conditions was 2.5 +/- 0.7%. From logistic regression, ED50 and ED95 were 2.0% (95% CI 1.3-2.5) and 3.2% (95% CI 2.6-5.6), respectively. With sevoflurane 2.5%, heart rate and mean arterial pressure decreased by 18% and 15%, respectively, after remifentanil administration and increased slightly after tracheal intubation.

Adolescent↗
PubMed1999

[Fastrach laryngeal mask and difficult intubation].

OBJECTIVE: To evaluate the success rate of intubation through the intubating laryngeal mask airway (LMA-Fastrach) in patients with predictive signs of difficult airway or after intubation failure. STUDY DESIGN: Open prospective study. PATIENTS: The study included 33 adults, 21 with predictive signs of difficult airway and 12 after intubation failure. METHODS: After induction of anaesthesia, the intubating LMA was inserted. Proper insertion was confirmed by easy bag ventilation and capnography. Intubation through the intubating LMA was then carried out with an armoured endotracheal tube. If intubation failed, a second attempt was carried out after a gentle manipulation of the intubating LMA. After two attempts, if intubation remained impossible, fibrescopic intubation through the intubating LMA was carried out. In case of failure the usual tracheal intubation algorithms were used. RESULTS: Tracheal intubation through the intubating LMA was successful in all patients, in 32 on the first attempt and in one on the second. Successful tracheal intubation was possible on the first attempt in 25 patients (76%), on the second in four (12%) and after fibrescopic intubation through the intubating LMA in the four remaining (12%). CONCLUSION: The results of this study confirm that tracheal intubation through the intubating LMA can be recommended in patients with a difficult airway, whether foreseen or not.

Algorithms↗
PubMed1999

[Procedures use by French anesthetists in cases of difficult intubation and the impact of a conference of experts].

OBJECTIVE: To analyse the management of difficult intubation (DI) by French anaesthetists and the impact of the French experts' conference (EC) on this topic. STUDY DESIGN: Prospective, comparative, before/after study by questionnaire carried out in Aquitaine, Provence-Alpes-Côte d'Azur and Alsace-Lorraine. MATERIAL AND METHODS: A questionnaire on demographical data, detection of DI, management techniques and desiderata for continuing education on DI, was sent three months before the publication of the EC to 100 randomly selected anaesthetists, in each region (group PRE). Three months after the diffusion of the EC, the questionnaire completed by a survey on the impact of the EC was sent to 100 other randomly selected anaesthetists in each region (group POST). In the latter group, anaesthetists who considered the EC were compared to those who did not. RESULTS: The participation rate was 91% for the group PRE and 79% for the group POST respectively. Both groups were not significantly different for age, gender, position and seniority. Most used techniques that included blind nasal intubation (84%), intubation through laryngeal mask (82%), and intubation with fibrescope (53%). Demands for additional training were for translaryngeal ventilation (68%), intubation with fibrescope (64%), retrograde intubation (52%), and intubation through a laryngeal mask (46%). The EC was known by 71% of anaesthetists. In this group, the EC improved the assessment rate of the three recommended predictive criteria for DI from 12 to 28% (P < 0.02), but neither the management policy, nor the desiderata for additional training. CONCLUSION: Currently, the search of predictive indicators for DI is not systematically applied. The EC has only slightly modified the practice patterns. The need for additional training is important.

Anesthesiology↗
PubMed1999

[Guidelines on difficult intubation in anesthesia: evaluation of 2 information diffusion methods].

BACKGROUND: In 1996, experts from the Société Française d'Anesthésie et de Réanimation published guidelines about difficult intubation. We aimed to assess the effectiveness of two diffusion methods of these guidelines, media versus direct mailing plus media diffusion, and the relation between reading of the guidelines and practice behavior and training willingness. METHODS: Data were collected in two different samples of 300 anesthetists from three regions for pre and post-intervention surveys (E1 and E2 samples). Half of the anesthetists from E2, randomly chosen, received a direct mailing of the guidelines (E2a sample). The remaining constituted the E2b sample. Three assessment criteria were used, two concerning practice behavior and one training willingness. Relationship between these criteria and diffusion methods and reading was tested using logistic regression. RESULTS: The response rates were respectively 91%, 80% and 78% in the E1, E2a and E2b samples. The socio-professional features were not statistically different between the three samples. There was no relationship between the criteria and the diffusion methods. The direct mailing did not increase the reading rate (81% and 82% respectively in the E2a and E2b samples). The rate of anesthetists who routinely screened for predictive signs of difficult intubation (one of the practice criteria) was higher in E2a than in E2b (28% and 12% respectively). In the multivariate analysis, the difference only appeared among the sub-group of anesthetists who did not receive the direct mailing. The private practice was associated with a lower rate of routine screening. CONCLUSION: No impact of the diffusion methods on practice behavior and training willingness was found. Reading was inconstantly associated with practice behavior.

Adult↗
PubMed1999

[Role of the ORL anesthetist in foreseen or unforseen difficult intubations].

Difficult intubation (DI) is a daily problem in a ENT unit. The place of the ENT anesthesiologist in the management of a DI is both in his own unit and in the hospital as an expert in DI. An anesthesiologist working in a ENT unit should be an expert in techniques allowing to manage intubation and oxygenation in every situations: i.e. fiberscopic intubation, LMA and intubating LMA and transtracheal ventilation. The ENT anesthesiologist may also play a role in the management of a DI in the hospital as an expert, both helping to cope with a difficult airway and teaching airway skills and the value of having a plan before managing any airway.

Anesthesiology↗