Rescue transtracheal jet ventilation during difficult intubation in patients with upper airway cancer.

INTRODUCTION: The failure rates of intubation and/or mask ventilation are higher in patients with neck or upper airway disease. To ensure oxygenation, rescue trans-tracheal jet ventilation (RTTJV) may be used. In this critical situation, a high rate of complications has been reported. The aim of this study was to report RTTJV performed by a jet ventilator with an end-expiratory pressure control in an experienced institution. PATIENTS AND METHODS: From a computerised database of 63,905 anaesthesia cases, the anaesthetic reports of patients who underwent emergency RTTJV during intubation were studied retrospectively. The following information were analysed: anaesthetic procedures, data from the monitoring: lowest SpO2, duration of SpO2<90%, and complications. Success of emergency RTTJV was defined when SpO2 was>90% under jet ventilation. RESULTS: RTTJV was used in 31 patients, of whom 26 had upper airway cancer, (pre-treatment, n=9, post-treatment, n=17). Difficult intubation was anticipated in 15 out of 31 cases including six fiber-optic-aided intubations under spontaneous ventilation. RTTJV was effective in all cases with quick restoration of oxygenation (SpO2>90%). During jet ventilation, final airway control was performed either by oral intubation (n=25) or tracheotomy (n=1) in a short delay (mean: 8.1±1.7min). Subcutaneous emphysema was observed in one case without pneumothorax. CONCLUSION: RTTJV with end-expiratory pressure control allowed oxygenation during difficult intubation, with a low rate of complications.

Difficult intubation and extubation in adult anaesthesia.

OBJECTIVE: To provide an update to French guidelines about "Difficult intubation and extubation in adult anaesthesia 2006". DESIGN: A consensus committee of 13 experts was convened. A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Few recommendations were ungraded. METHODS: The panel focused on 6 questions: 1) Why must oxygen desaturation be avoided during intubation and what preoxygenation and oxygenation techniques should be used to prevent it? 2) Should videolaryngoscopes be used instead of standard laryngoscopy with or without a long stylet to achieve a better success rate of intubation after the first attempt during anticipated difficult intubation off fiberoptic intubation? 3) Should TCI or target controlled inhalation anaesthesia (TCIA) be used instead of bolus sedation for airway control in the event of suspected or proven difficulty in a patient spontaneously breathing? 4) What mode of anaesthesia should be performed in patients with difficult intubation criteria and potentially difficult mask ventilation? 5) In surgical patients, what criteria predict difficulties encountered during postoperative tracheal extubation? 6) Should decision trees and algorithms be employed to direct decision-making for the management of difficult intubation, whether foreseen or not? (based on the information from the preceding five issues). Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. The analysis of the literature and the recommendations were then conducted according to the GRADE® methodology. RESULTS: The SFAR Guideline panel provided 13 statements on difficult intubation and extubation in adult anaesthesia. After two rounds of discussion and various amendments, a strong agreement was reached for 99% of recommendations. Of these recommendations, five have a high level of evidence (Grade 1±), 8 have a low level of evidence (Grade 2±). No recommendation was provided for one question. CONCLUSIONS: Substantial agreement exists among experts regarding many strong recommendations for the best care of patients with difficult intubation and extubation in adult anaesthesia.

[Benchmark of a high-frequency jet ventilator, the Mistral]. / Etude d'un respirateur de jet ventilation, le Mistral, sur banc d'essai.

OBJECTIVE: To test a high-frequency jet ventilator, the Mistral (Acutronic Laboratory) on a lung model. METHODS: The jet ventilator Mistral was tested with two connectors (7 and 20 ml) and four catheters. Pressure and flow measurements were performed by varying the driving pressure (1 to 3 bars), the I/T ratio (0.25, 0.35, 0.45) and the frequency (1 to 5 Hz). Recorded data were: the volume delivered by the ventilator, the pressure measured in the connecting line between the ventilator and the injector and the difference between the end expiratory pressure measured by the ventilator through the injector and the tracheal pressure. RESULTS: An increase in driving pressure induced a proportional increase in minute volume whatever the injection catheter used. After insufflation, when a Seldicath catheter was used, the pressure decrease was the slowest and the time constant the longest. Increase in frequency or I/T ratio, particularly beyond 0.35, was associated with an increase of the end expiratory pressure measured by the respirator. The gradient of pressure measured by the respirator and by an external sensor was lower with the 7 ml connector whatever the catheter used, and was larger with the Seldicath catheter. CONCLUSION: The use of a low volume connector should be preferred, because it allows the measurement of the end expiratory pressure for a larger range of driving pressure, expiratory time and catheters. The performances of the Seldicath catheter are below those of the other catheters studied.

Preoxygenation and general anesthesia: a review.

Because intubation can potentially become a lengthy procedure, the risk of arterial oxygen (O2) desaturation during intubation must be considered. Preoxygenation should be routine, as oxygen reserves are not always sufficient to cover the duration of intubation. Three minutes of spontaneous breathing at FiO2=1 allows denitrogenation with FAO2 close to 95% in patients with normal lung function. Tolerable apnea time, defined as the delay until the SpO2 reaches 90%, can be extended up to almost 10 minutes after 3 minutes of classic preoxygenation. Eight deep breaths within 60 seconds allow a comparable increase in O2 reserves. For effectiveness, the equipment must be adapted and tightly fitted. Inadequate preoxygenation (FeO2 <90% after three minutes tidal volume breathing) is frequently observed. Predictive risk factors for inadequate pre-oxygenation share overlap with criteria predictive of difficult mask ventilation. In cases of respiratory failure, oxygenation can be improved by positive end expiration pressure or by pressure support. In morbidly obese patients, preoxygenation is enhanced in a seated position (25°) and by use of positive pressure ventilation. O2 can also be administered during the intubation procedure; techniques include pharyngeal O2, special oxygen mask, or even pressure support ventilation for patients with spontaneous ventilation or positive pressure ventilation to the facial mask for apneic patients. Clinicians (especially anesthesiologists trained in ENT and traumatology) must be prepared to handle life-threatening emergency situations by alternate methods including trans-tracheal ventilation. The availability of equipment and training are two essential components of adequate preparation.

High-frequency jet ventilation vs continuous positive airway pressure for postoperative respiratory support.

In ten patients after recovery from general anesthesia for major vascular surgery, we compared continuous positive airway pressure (CPAP) and high-frequency jet ventilation (HFJV) at the same fractional concentration of oxygen in the inspired gas, both being superimposed on spontaneous breathing. The HFJV was delivered by a ventilator ( Acutronic VS-600) through the lateral lumen of a three-lumen endotracheal tube. Mean airway pressure was increased (3, 8, and 11 mm Hg) by adjusting the driving pressure during HFJV and by the setting of the expiratory valve during CPAP. During HFJV, the frequency (10 Hz) and inspiratory-expiratory ratio (0.25) were kept constant. Control values were measured when patients breathed spontaneously without positive end-expiratory pressure. Cardiac output and transmural filling pressures remained unchanged throughout the study. Neither the arterial oxygen pressure (PaO2) nor intrapulmonary shunt (Qs/Qt) changed significantly during CPAP. The 20- to 30-percent increase in PaO2 and the 5- to 10-percent decrease in Qs/Qt during HFJV when compared to control reflected a slightly but significantly (p less than 0.05) better oxygenation. The increase in arterial carbon dioxide tension was significantly greater during CPAP than during HFJV.

Differential ventilation in unilateral lung disease: effects on respiratory mechanics and gas exchange.

Conventional PEEP ventilation has been recently reported to be deleterious in some cases of ARF with unilateral pneumonia. In such respect, two cases of unilateral bacterial pneumonia were intubated with a Carlens tracheal tube. Measurement of tidal volume, static compliance, and functional residual capacity of each lung showed marked inequality. Subsequently, both patients were ventilated with a selective distribution circuit, allowing the introduction of a PEEP valve in the expiratory line of the diseased lung. Evident improvement in blood gases was obtained within 24 hours, as tidal volume, static compliance, and FRC of the diseased lung were markedly improved. In one case equalisation of V/Q ratio was documented using the 81m Kr method. Final recovery was obtained in one case.

Postoperative pulmonary complications: general anesthesia with postoperative parenteral morphine compared with epidural analgesia.

In a prospective study, patients undergoing abdominal cancer surgery were randomly allocated to receive either general anesthesia with fentanyl intravenously and postoperative analgesia with parenteral morphine (GA group) or general anesthesia combined with epidural bupivacaine and epidural morphine for postoperative pain relief (EP group). Analgesia was tested on a visual pain scale. Pulmonary complications were evaluated by clinical complications, blood gas analysis, x-ray film changes, and pulmonary volumes (vital capacity, forced expiratory volume in 1 second). Measurements were performed on the day before the operation and on the first 5 postoperative days. In the EP group the pain relief was significantly better on the first day (p less than 0.03). Whatever the criteria used, the rates of pulmonary complications were similar in the two groups: clinical complications 21% versus 26%, radiologic complications 50% versus 64% for GA and EP groups, respectively. Postoperative PaO2 and spirometric values were similar in the two groups. Postoperative epidural analgesia may improve the patient's comfort but does not decrease the incidence of pulmonary complications.

Mechanisms and risk factors for infection of pulmonary artery catheters and introducer sheaths in cancer patients admitted to an intensive care unit.

Pulmonary artery catheters (PACs) are typically inserted for short periods, and the extra-luminal route is assumed to be the overriding source of contamination and/or infection. Our aim was to assess the incidence of PAC and introducer colonization in cancer patients, and to study the mechanisms and risk factors for infection. Patients with a Swan-Ganz catheter admitted to an intensive care unit were prospectively analyzed over 14 months. As soon they were no longer necessary, PACs and introducer sheaths were removed and cultured. We recorded the mean duration of placement, the number of times PACs were handled and the site of insertion. Seventy-nine catheters were inserted in 68 patients. The median (range) duration was three days (0-10) for PACs, and 3.6 days (0-18) for introducers. PAC and/or percutaneous introducer sheath colonization was diagnosed in seven patients (8.9%), but in only one case were both colonized. Colonization rates were 15.5 per 1000 days for PACs and 14.1 per 1000 days for introducers. Introducers were mainly colonized before the 5th day, while PACs were mainly colonized after the 5th day. No PAC or introducer-related local infection or bacteraemia was diagnosed. Colonization was more frequent on catheters inserted into the internal jugular vein. The colonization rate was 5% for PACs and introducers. Our findings suggest that contamination of introducers and PACs may be dissociated and could result from either extraluminal or endoluminal colonization. As three of four PAC colonizations occurred after 5 days, the duration of catheter placement should be considered important. There was little clinical impact of microbial colonization.

Airway obstruction and high-frequency jet ventilation during laryngoscopy.

High-frequency jet ventilation has been reported as an effective method of ventilation during laryngoscopy, but may expose the patient to the risks of barotrauma or alveolar hypoventilation. The aim of the study was to evaluate the determining factors of pulmonary complications under high-frequency jet ventilation in 83 patients undergoing laryngoscopy for upper airway cancer. Pulmonary distention was mainly influenced by upper airway obstruction score (p = .0001), while patients with chronic obstructive pulmonary disease (COPD) did not suffer from gas trapping. Impaired gas exchange was predicted by increased weight (p = .0001), smaller injector diameter (p = .02), and lower airway obstruction (p = .001). Hypercapnia occurred in both upper and lower airway obstruction, while hypoxemia was principally observed in COPD patients. Emphasis is placed on monitoring by pulse oximetry, end-expiratory pressure, and PCO2 measurement, especially in patients with obesity, COPD, or upper airway obstruction.

Reconstruction with free jejunal autograft after circumferential pharyngolaryngectomy: eighty-three cases.

The free jejunal autograft (FJA) has become a common procedure for pharyngeal reconstruction after circumferential pharyngolaryngectomy. In order to evaluate the postoperative outcome and the functional and carcinologic results, we retrospectively reviewed 83 cases of reconstruction with FJA. Fifty-one patients had received no prior radiotherapy, and 25 had received prior radiotherapy for their hypopharyngeal tumor or for another previous primary. Seven patients underwent a secondary reconstruction. In the postoperative course, there were 2 postoperative deaths, 4 graft failures (5%), and 11 salivary fistulas. The median time to removal of the nasogastric tube was 16 days, and to discharge, 23 days. Forty-eight patients received postoperative radiotherapy, with good tolerance. At 1 year postoperatively, 98% of the patients were able to eat a solid or soft diet. The postoperative radiotherapy did not impair the quality of the functional results in a long-term assessment. The vocal results were disappointing. The 3-year survival rate was 40%. The main carcinologic failures (45 patients) were locoregional recurrences (20 patients) and metastasis, which was the cause of death in 34% of the cases. It seems clear that FJA allows one-stage reconstruction and good swallowing rehabilitation, tolerates postoperative radiotherapy, and increases the quality of life in these patients with a poor prognosis.

[Use of Diprivan in chronic respiratory insufficiency]. / Utilisation du Diprivan chez l'insuffisant respiratoire chronique.

Propofol may be recommended as an anaesthetic agent in patients with chronic respiratory insufficiency since: it prevents the increase in bronchial resistances resulting from the administration of opioids; it possesses a bronchodilator effect, comparable with that of flunitrazepam; it ensures rapid recovery, which would favour patient's co-operation postoperatively. The effects of propofol on respiratory drive should not be neglected, as they may persist even after complete recovery. In pulmonary surgery, propofol may be recommended in patients with one-lung ventilation, since it does not depress the hypoxic vasoconstriction reflex. Some procedures may be carried out in spontaneous ventilation or, preferably, using jet ventilation, provided that propofol is given by means of an infusion pump.

[Preoxygenation and upper airway patency control]. / Préoxygénation et manoeuvres de contrôle de la perméabilité des voies aériennes.

During preoperative assessment, risk factors of upper airway obstruction should be evaluated: respiratory insufficiency, low O(2) reserve, preoxygenation failure or difficult face mask ventilation. In healthy subjects, spontaneous breathing O(2) for 3 min is the reference method. Apnoea duration is longer after preoxygenation than after denitrogenation, even if FEO(2) and SpO(2) do not change during the two last minutes of preoxygenation. The apnea time is longer after 3 min spontaneous breathing than after four deep breaths for 1 min in most of the literature. Maximal breathing during 2 min can produce values comparable to those obtained with tidal volume breathing for 3 min. FEO(2) monitoring is helpful in the assessment of preoxygenation quality: In case of oxygenation impairment during anaesthesia induction, algorithm use is helpful. Because desperate emergencies will occur in association with anaesthesia, every location should have the immediate availability of Fastrach and trans tracheal ventilation. Every anaesthesiologist should be familiar with and well practised in a variety of airway management techniques. Teaching programs are organised in order to develop anaesthesiologist sensitisation and skill.

[Morbidity after cervicofacial cancer surgery]. / Morbidité de la chirurgie carcinologique cervicofaciale.

Identification of specific risk factors by analysis of complications and new reconstructive surgical procedures has changed anaesthesia practice for cervicofacial cancer surgery. In spite of difficult airways and long duration of surgery, the incidence of complications is low. Adapted protocols for patients with cardiac or respiratory diseases allow the reduction of complication rate. Nevertheless, risk of early postoperative death persists and justifies careful monitoring during the first days after surgery. Incidence of local infection remains high.

[Transtracheal jet ventilation with spontaneous ventilation in neoplastic laryngeal dyspnea]. / Jet-ventilation transtrachéale avec ventilation spontanée lors des dyspnées laryngées d'origine néoplasique.

In six suffocating patients with a severe upper airway obstruction (three patients after direct laryngoscopy under general anaesthesia and three patients with cervical tumor scheduled for a difficult tracheostomy), jet-ventilation was delivered using a transtracheal catheter. The jet-ventilator insufflated oxygen only when the tracheal pressure was below a preset value, during spontaneous inspiration. During expiration, tracheal pressure increased above the preset value, the ventilator stopped the insufflation and the expiratory gases escaped through the upper airway. This method corresponds to an inspiratory support without intubation. In post-anaesthesia patients, oxygenation and alveolar ventilation were improved, allowing the avoidance of tracheostomy. In the other patients, tracheostomy was made possible with good surgical conditions under general anaesthesia. This method can be applied in conscious patients and allows oxygenation of suffocating patients.

[A survey of operating and recovery room ventilators and monitoring equipment as well as their maintenance]. / Enquête sur les ventilateurs et les moniteurs de salle d'opération et de salle de réveil et leur maintenance.

OBJECTIVE: To survey the monitoring and anaesthetic devices available in a sample of French hospitals and the modalities of their maintenance. STUDY DESIGN AND METHOD: Survey carried out in 21 private and public hospitals (including eight university hospitals), affilated to the French Association for Research in Anaesthesia and Intensive Care (ARAR). RESULTS: More than 84% of all operating theaters were equipped with at least an ECG, a SpO2, and a non invasive blood pressure monitor. The non equipped anaesthesia sites were mainly delivery rooms, plaster cast rooms and X-ray rooms. The figure of recovery room beds was, generally speaking in accordance with the French recommendations. Maintenance policy was not systematic and not budgeted in 72% of the surveyed centres. CONCLUSION: The equipment in most anesthetic sites has significantly increased, however maintenance policy remains still heterogenous.

[Pros and cons of adding an accessory breathing system to the main circle circuit. II. Arguments against their use]. / Pour ou contre les circuits anesthésiques accessoires. II. Arguments contre leur utilisation.

When compared to the circle system alternative breathing systems (ABS) are of no benefit. When the only indication of an ABS is emergency oxygen administration it should be connected to the O2 pipeline upstream from the flowmeter bank and the vaporiser. The use of an ABS for anaesthesia maintenance is no longer justified because of the difficulties in monitoring pressure, flow and concentrations of the gas mixture, the cost of gas and vapour administered at a high flow and the resulting pollution. The use of an ABS for very short anaesthetics is only acceptable if the administered gas mixture is monitored.

[French survey on anesthesia systems and peroperative respiratory monitoring equipment]. / Enquête française sur les systèmes d'anesthésie et l'équipement de surveillance respiratoire peropératoire.

A national inquiry has been carried out in France. It concerned the anaesthetic systems and respiratory monitoring equipment in use at the moment, as well as that wished for. The equipment in use was very stereotyped: an open system with a respirator, for the most volumetric, and with a safety O2/N2O mixer. Monitoring is carried out with the pressure gauges and the measure of expiratory volume; only two thirds of the equipment had an alarm. The O2 and CO2 analysers were little used. Expired CO2 monitoring was only carried out in teaching hospitals and in big centres. Apart from this, the equipment was independent of the hospital and the type of surgery carried out. As for anaesthetic systems, 53% of centres would like obtain open systems, 15% closed systems; 32% did not answer. This increase in number of closed systems is not significant. However, a very strong wish for respirators with flow rate control and safety O2/N2O mixers was observed, whilst the safety parameters of these mixers were open to discussion. Respiratory monitoring was not just confined to the mechanical aspects, as 65% of centres wished to monitor FIO2. The big centres and the teaching hospitals were interested by the expiratory CO2 monitoring. This inquiry showed the interest in respiratory safety in operating theatres. Further studies should confirm or not the increasing interest in closed systems.

[Pressure control in medical gas distribution systems]. / Contrôle des pressions dans les systèmes de distribution de gaz médicaux.

OBJECTIVE: To assess whether the pressure gauges at the downstream part of pressure regulators are accurate enough to ensure that pressure in O2 pipeline is always higher than in Air pipeline and that pressure in the latter is higher than pressure in N2O pipeline. A pressure difference of at least 0.4 bar between two medical gas supply systems is recommended to avoid the reflow of either N2O or Air into the O2 pipeline, through a faulty mixer or proportioning device. STUDY DESIGN: Prospective technical comparative study. MATERIAL AND METHODS: Readings of 32 Bourdon gauges were compared with data obtained with a calibrated reference transducer. Two sets of measurements were performed at a one month interval. RESULTS: Pressure differences between Bourdon gauges and reference transducer were 8% (0.28 bar) in average for a theoretical maximal error less than 2.5%. During the first set of measurements, Air pressure was higher than O2 pressure in one place and N2O pressure higher than Air pressure in another. After an increase in the O2 pipeline pressure and careful setting of pressure regulators, this problem was not observed at the second set of measurements. DISCUSSION: Actual accuracy of Bourdon gauges was not convenient enough to ensure that O2 pressure was always above Air pressure. Regular controls of these pressure gauges are therefore essential. Replacement of the faulty Bourdon gauges by more accurate transducers should be considered. As an alternative, the increase in pressure difference between O2 and Air pipelines to at least 0.6 bar is recommended.

[The breakdown of anesthesia equipment survey]. / Enquête sur les pannes des appareils d'anesthésie.

OBJECTIVE: To assess the incidence and the causes of failures of anaesthesia machines. STUDY DESIGN: Prospective survey from August 1995 to September 1997. MATERIAL: Check-list and machine failure forms. METHODS: Failures of anaesthetic machines have been collected and entered into a database. Causes and treatment of each failure have been analysed. RESULTS: Of 5,096 foreseen forms, 3,926 (77%) have been completed after check-list or anaesthesia machine failure. Overall, 233 incidents have been declared (4.5%). Failures identified during the preoperative check-list (n = 96) were mainly related to mechanical problems, especially the gas proportioning device (35%). Perioperative failures (n = 137) were mostly related to electronic problems (ventilator: 27% and monitor: 57%). In more than half of the cases, a specially trained anaesthetic nurse was able to correct the failure in the operating theatre. Using 14 anaesthetic machines for 12 operating rooms, no procedure was cancelled because of a technical failure of a machine. CONCLUSIONS: This study emphasizes the value of the check-list and the failure report. The presence of a specially trained anaesthetic nurse allows immediate correction of the majority of technical problems.