High-Frequency Jet Ventilation Versus Spontaneous Respiration for Percutaneous Cryoablation of Lung Tumors: Comparison of Adverse Events and Procedural Efficiency

BACKGROUND. High-frequency jet ventilation (HFJV) facilitates accurate probe placement in percutaneous ablation of lung tumors but may increase risk for adverse events, including systemic air embolism. OBJECTIVE. The purpose of this study was to compare major adverse events and procedural efficiency of percutaneous lung ablation with HFJV under general anesthesia to spontaneous respiration (SR) under moderate sedation. METHODS. This retrospective study included consecutive adults who underwent CT-guided percutaneous cryoablation of one or more lung tumors with HFJV or SR between January 1, 2017, and May 31, 2023. We compared major adverse events (Common Terminology Criteria for Adverse Events grade ≥ 3) within 30 days postprocedure and hospital length of stay (HLOS) of 2 days or more using logistic regression analysis. We compared procedure time, room time, CT guidance acquisition time, CT guidance radiation dose, total radiation dose, and pneumothorax using generalized estimating equations. RESULTS. Overall, 139 patients (85 women, 54 men; median age, 68 years) with 310 lung tumors (82% metastases) underwent 208 cryoablations (HFJV, n = 129; SR, n = 79). HFJV showed greater rates than SR for the treatment of multiple tumors per session (43% vs 19%, respectively; p = .02) and tumors in a nonperipheral location (48% vs 24%, p < .001). Major adverse event rate was 8% for HFJV and 5% for SR (p = .46). No systemic air embolism occurred. HLOS was 2 days or more in 17% of sessions and did not differ significantly between HFJV and SR (p = .64), including after adjusting for probe number per session, chronic obstructive pulmonary disease, and operator experience (p = .53). Ventilation modalities showed no significant difference in procedure time, CT guidance acquisition time, CT guidance radiation dose, or total radiation dose (all p > .05). Room time was longer for HFJV than SR (median, 154 vs 127 minutes, p < .001). For HFJV, the median anesthesia time was 136 minutes. Ventilation modalities did not differ in the frequencies of pneumothorax or pneumothorax requiring chest tube placement (both p > .05). CONCLUSION. HFJV appears to be as safe as SR but had longer room times. HFJV can be used in complex cases without significantly impacting HLOS of 2 days or more, procedure time, or radiation exposure. CLINICAL IMPACT. Selection of the ventilation modality during percutaneous lung ablation should be based on patient characteristics and anticipated procedural requirements as well as operator preference.

High-flow Nasal Cannula versus Conventional Ventilation in Laryngeal Surgery: A Systematic Review and Meta-analysis

High-flow nasal cannula (HFNC) is an emerging option for maintaining oxygenation in patients undergoing laryngeal surgery, as an alternative to traditional tracheal ventilation and jet ventilation (JV). However, the data on its safety and efficacy is sparse. This study aims to aggregate the current data and compares the use of HFNC with tracheal intubation and jet ventilation in adult patients undergoing laryngeal surgery. We searched PubMed, MEDLINE (Medical Literature Analysis and Retrieval System Online, or MEDLARS Online), Embase (Excerpta Medica Database), Google Scholar, Cochrane Library, and Web of Science. Both observational studies and prospective comparative studies were included. Risk of bias was appraised with the Cochrane Collaboration Risk of Bias in Non-Randomized Studies - of Interventions (ROBINS-I) or RoB2 tools and the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for case series. Data were extracted and tabulated as a systematic review. Summary statistics were performed. Meta-analyses and trial sequential analyses of the comparative studies were performed. Forty-three studies (14 HFNC, 22 JV, and seven comparative studies) with 8064 patients were included. In the meta-analysis of comparative studies, the duration of surgery was significantly reduced in the THRIVE (Transnasal Humidified Rapid-Insufflation Ventilatory Exchange) group, but the number of desaturations, need for rescue intervention, and peak end-tidal CO₂ were significantly increased compared to the conventional ventilation group. The evidence was of moderate certainty and there was no evidence of publication bias. In conclusion, HFNC may be as effective as tracheal intubation in oxygenation during laryngeal surgery in selected adult patients and reduces the duration of surgery but conventional ventilation with tracheal intubation may be safer. The safety of JV was comparable to HFNC.

Jet Ventilation Reduces Coronary Sinus Movement in Patients Undergoing Atrial Fibrillation Ablation: An Observational Crossover Study

BACKGROUND

One of the reasons that high-frequency jet ventilation (HFJV) is used is due to the near immobility of thoracic structures. However, no study has quantified the movements of cardiac structures during HFJV compared with normal mechanical ventilation.

METHODS

After ethical approval and written informed consent, we included 21 patients scheduled for atrial fibrillation ablation in this prospective crossover study. Each patient was ventilated with both normal mechanical ventilation and HFJV. During each ventilation mode, displacements of the cardiac structure were measured by the EnSite Precision mapping system using a catheter placed in the coronary sinus.

RESULTS

The median [Q1-Q4] displacement was 2.0 [0.6-2.8] mm during HFJV and 10.5 [9.3-13.0] mm during conventional ventilation (p < 0.000001).

CONCLUSION

This study quantifies the minimal movement of cardiac structures during HFJV compared to standard mechanical ventilation.

Evaluation of Supraglottic Jet Oxygenation and Ventilation in 105 Patients During Bronchoscopy Using the Twinstream® Microprocessor-Controlled Jet Ventilator and the Wei Nasal Jet® Tube

BACKGROUND The Twinstream® ventilator is a microprocessor-controlled electric jet ventilator that allows the simultaneous application of 2 different jet streams, one at low frequency and one at high frequency to result in pulsatile bi-level (p-BLV) mode of ventilation. This study aimed to evaluate supraglottic jet oxygenation and ventilation in 105 patients during bronchoscopy using the Twinstream® microprocessor-controlled jet ventilator and the Wei Nasal Jet® (WNJ) tube. MATERIAL AND METHODS Patients were randomly divided into 2 parallel groups (N=50 per group): group W using the WNJ tube and group M using an endoscopic face mask connected to Twinstream® microprocessor-controlled jet ventilator under monitored anesthesia care. Arterial blood gas was examined and recorded 15 minutes after the initiation of procedure. The demographic and clinical characteristics, procedure duration, doses of anesthetics, and adverse events in the 2 groups were also recorded. RESULTS The arterial partial pressure of carbon dioxide (PaCO₂) (P=0.006) and lactic acid (P=0.001) were significantly lower, while pH (P=0.024) was significantly higher than in the group M. Pearson analysis showed that PaCO₂ was significantly correlated with ventilation tools (P=0.006) and procedure duration (P=0.003). Multiple linear regression analysis showed that ventilation tools and procedure duration were both independent influencing factors (P=0.006, P=0.002). CONCLUSIONS Supraglottic jet oxygenation and ventilation using the WNJ tube can reduce PaCO2 and had advantages in enhancing oxygenation and ventilation function in patients during bronchoscopy intervention therapy under monitored anesthesia care.

A New Approach in Airway Management for Tracheal Resection and Anastomosis: A Single-Center Prospective Study

OBJECTIVES

The evaluation of the use of laryngeal mask airways (LMA) as an alternative form of airway management for surgical tracheal reconstruction.

DESIGN

A prospective case series.

SETTING

At a single German university hospital.

PARTICIPANTS

Ten patients.

INTERVENTIONS

The use of LMA for airway management in surgical reconstruction of the trachea.

MEASUREMENTS AND MAIN RESULTS

Ten patients with tracheal stenosis of 50% to 90% were enrolled prospectively during the study period. The airway management consisted of the insertion of an LMA. During resection and reconstruction, high-frequency jet ventilation was used. Several arterial blood gas analyses (ABG) were performed before, during, and after the tracheal resection and reconstruction. All values were presented as median and interquartile ranges or as absolute and relative values, and no emergency change to cross-field intubation was necessary. The lowest PaO₂ was 93 mmHg in 1 patient after 20 minutes of jet ventilation, whereas PaO₂ increased after the induction phase and remained stable in 9 patients. There were no intraoperative complications related to anesthetic management apart from transient hypercarbia during and after jet ventilation. Preoperative and postoperative ABG were comparable. One patient required immediate postoperative ventilatory support. Two patients developed postoperative pneumonia, leading to their admission to the intensive care unit. One patient was operated with a palliative approach due to massive dyspnea and died in the next postoperative course.

CONCLUSIONS

The use of LMA is an alternative option in airway management for tracheal reconstruction, even in patients with significant tracheal stenosis. Potential advantages compared to tracheal intubation are unimpaired access to the operative field and the lack of stress on the fresh anastomosis.

[Application of high frequency jet ventilation system in laryngopharyngeal and tracheal surgery]

Objective:The effectiveness and safety of high frequency ventilation system in laryngopharyngeal and tracheal surgery is discussed. Methods:According to The American Society of Anesthesiologists Ⅰ-Ⅱ level, 60 cases of selective throat and tracheal surgery undering general anesthesia were randomly divided into high frequency jet ventilation group （group HFJV） and intermittent positive pressure ventilation group （IPPV group）, with 30 cases in each group. Group HFJV was treated with HFJV and group IPPV with a small caliber endotracheal tube connected to an anesthesia machine was treated with IPPV.Before anesthesia （T0）, after the success of the laryngoscope placed （T1）, 5 minites after ventilation （T2） and 5 minites after the laryngoscope removed （T3）, hemodynamic parameters were recorded at each time point , in T0, T2 and T3 record , arterial blood gas index, the patient's airway pressure, end-expiratory carbon dioxide concentration, surgical field quality and total blood loss, operating time and awakening time were recorded and compared between the two groups. Results:The average airway pressure and intraoperative average total blood loss of group HFJV were significantly lower than that of group IPPV（P<0.01）, and the average operative field quality of group HFJV was significantly better（P<0.01）, but there was no statistical significance in the effects on hemodynamics, arterial blood gas and other indicators compared with group IPPV（P>0.05）. No serious adverse events occurred in 2 groups. Conclusion:HFJV system can be used effectively in laryngopharyngeal and tracheal surgery, reducing intraoperative blood loss and improving surgical field of vision without obvious adverse reactions.

Post-operative hypertension during early recovery following liver tumour ablation: A retrospective study

BACKGROUND

High-frequency jet ventilation is necessary to reduce organ movements during stereotactic liver ablation. However, post-operative hypertensive episodes especially following irreversible electroporation ablation compared with microwave ablation initiated this study. The hypothesis was that hypertensive episodes could be related to ventilation or ablation method.

METHODS

The aim of this retrospective study was to assess the proportion of patients with hypertensive events during recovery following liver ablation under general anaesthesia and to analyse the relation to ventilation and ablation technique. A medical chart review of 134 patients undergoing either high-frequency jet ventilation and microwave ablation (n = 45), high-frequency jet ventilation and irreversible electroporation (n = 44), or conventional ventilation and microwave ablation (n = 45) was performed. The proportion of patients with at least one episode of systolic arterial pressure 140-160, 160-180 or >180 mmHg during early recovery and the impact of ventilation method was studied.

RESULTS

Out of 134 patients, 100, 75 and 34 patients had at least one episode of mild, moderate and severe hypertension. Microwave ablation, as well as high frequency jet ventilation, was associated with an increased odds ratio for post-operative hypertension. The proportion of patients with at least one severe hypertensive event was 18/45, 9/44 and 7/45, respectively.

CONCLUSION

Both ventilation and ablation technique had an impact on post-operative hypertensive episodes. The microwave ablation/high-frequency jet ventilation combination increased the risk as compared with irreversible electroporation/high-frequency jet ventilation and microwave ablation/conventional ventilation.

Utility of High-frequency Jet Ventilation in Atrial Fibrillation Ablation

Atrial fibrillation (AF) is the most common clinically significant arrhythmia that causes major morbidity and mortality. Catheter ablation focusing on pulmonary vein isolation is increasingly used for the treatment of symptomatic AF. Advances in ablation technologies and improved imaging and mapping have enhanced treatment efficiency but only modestly improved the efficacy. Another-but less commonly used-technology that can have a favorable impact involves enhancing the catheter-tissue contact by manipulating respiration to promote improved catheter stability and optimal contact. High-frequency jet ventilation (HFJV) is a mode of ventilation that can reduce respiratory movements to almost apneic conditions. In this review article, we aimed to highlight different studies, review the current literature regarding the utility of HFJV in AF ablation, and discuss the safety and efficacy of this approach relative to that of conventional ventilation.

Closing an Intractable Tracheoesophageal Fistula Caused by a Tracheoesophageal Shunt Using a Myocutaneous Flap and a Hinged Flap With Skin Graft in a Two-Step Procedure

Total laryngectomy involves removal of the vocal cords resulting in the loss of vocal function. After laryngectomy, the patient's vocal function can be restored in several ways, including the insertion of a tracheoesophageal (TE) shunt. A TE shunt is considered an effective means of restoring speech due to its high efficacy, low requirement for training, and no need for any equipment while speaking. However, complications such as saliva inflow into the trachea, caused by the widening of the shunt opening, have also been reported. Moreover, the optimal treatment for an enlarged fistula has not yet been established.

A fistula may also form at sites of hypopharyngeal reconstruction with free jejunal transplantation. Following its formation, the influx of saliva, infections, and pressure exerted by the act of swallowing make a fistula resistant to closure, and most patients require closure surgery using myocutaneous flaps.

We encountered a case where an intractable TE fistula formed due to a TE shunt after the patient underwent total pharyngolaryngeal resection for hypopharyngeal cancer and hypopharyngeal reconstruction with a free jejunum flap. Since the optimal method for the TE fistula closure remains uncertain, we attempted to close the fistula according to the fistula closure of the free jejunal transplantation.

Failure to close a TE fistula using a myocutaneous flap necessitates a re-closure procedure. However, because the surgical field around the trachea can be limited in such patients, creating an additional myocutaneous flap may not be feasible. In addition to the myocutaneous flap, ventilation control using a conventional intubation tube may further narrow the surgical field during the re-closure surgery. Based on our experience and existing literature, in this article, we summarize several ways of managing TE fistula when the surgical field around the trachea is limited.

High-Frequency Jet Ventilation in Neonatal and Pediatric Subjects: A Narrative Review

High-frequency ventilation is commonly utilized with neonates and with children with severe respiratory failure. Both high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) are used extensively in neonates. HFJV can also be used in older, larger children. The purpose of this narrative review is to discuss the physiologic principles behind HFJV, examine the evidence supporting its use in neonatal and pediatric ICUs, give meaningful guidance for clinical application, and highlight potential areas for future research.

Mortality Risk Factors in Preterm Infants Treated with High-Frequency Jet Ventilation

BACKGROUND

High-frequency jet ventilation (HFJV) has been used in conjunction with conventional ventilation for premature infants with respiratory failure. We sought to identify parameters that were associated with mortality in subjects who underwent HFJV.

METHODS

Subjects were enrolled if birthweight was ≤ 2,000 g and they were ≤ 34 weeks gestational age. Subjects were excluded if they received HFJV at the time of admission because we aimed to study subjects who failed conventional ventilation. Subject demographics, ventilator parameters, and laboratory data were extracted and analyzed. The Mann-Whitney U-test was used to assess differences in continuous variables, and the chi-square and Fisher exact tests were used for categorical variables between the groups. To assess variables that were predictive of mortality, we used both univariate and multivariate logistic regression analysis. Independent predictors of mortality were identified and used to create a multivariate risk score. Receiver operating characteristic curves were constructed to evaluate the predictive accuracy of the multivariate risk score.

RESULTS

A total of 53 premature subjects (n = 37 male) were studied, of whom 39 (74%) survived to discharge or transfer back to referring hospital. In the univariate model, female sex, older gestational age, higher birthweight, HFJV peak inspiratory pressure at 1 h, and oxygen saturation index at 4 h were associated with mortality. In the final multivariate logistic regression model, female sex (odds ratio 4.1, 95% CI 1.2-19.8, P = .044), closed ductus arteriosus (odds ratio 7.7, 95% CI 1.3-39.5, P = .016), and oxygen saturation index > 5.5 (odds ratio 6.0, 95% CI 1.5-28.3, P = .02) were independent predictors of mortality.

CONCLUSIONS

We identified that oxygen saturation index > 5.5 after 4 h of HFJV, female sex, and closed ductus arteriosus were independent predictors of mortality.

Anesthetic Considerations for Automated High-Frequency Jet Ventilation During Electromagnetic Navigation Bronchoscopy

Newly advanced diagnostic bronchoscopic procedures, such as electromagnetic navigation bronchoscopy using navigation system technology (superDimension, Medtronic), provides computed tomography referenced and computerized 3-dimensional imaging. To increase accuracy and higher diagnostic biopsy yield, electromagnetic navigation bronchoscopy necessitates special anesthetic and ventilation techniques providing the interventional pulmonologist minimal respiratory lung motion. This anesthetic meets 2 important goals by limiting almost all interference from diaphragmatic and lung movement while allowing the anesthesia provider to achieve hands-free management. Proposed here is an anesthetic ventilation technique by automated high-frequency jet ventilation (HFJV) via double-lumen micro jet endotracheal tubes. This ventilation technique delivers consistent very low tidal volumes. Automated HFJV provides the pulmonologist the advantage of more accurate navigation and target alignment in this Global Positioning System-guided biopsy procedure. The technique offers essentially no chest motion, without interrupting ventilation. Additionally, HFJV allows the anesthetist better availability to attend to total intravenous anesthesia, adjustments, and interventions. The intention of this article is to detail an anesthetic method that provides a hands-free technique that requires only one anesthesia provider.

Assessing Initial Response to High-Frequency Jet Ventilation in Premature Infants With Hypercapnic Respiratory Failure

BACKGROUND

High-frequency jet ventilation (HFJV) has been used in conjunction with conventional ventilation for infants with respiratory failure. We sought to identify parameters that were associated with successful application of HFJV in patients with hypercapnic respiratory failure.

METHODS

A single-center, retrospective review of infants who received HFJV was conducted. Subjects were enrolled if birthweight was ≤2,000 g and capillary P_CO2 was ≥55 mm Hg. Ventilator parameters and physiologic data were recorded at 1 h before HFJV initiation and at hours 1, 4, and 6 following conversion. Subjects were classified as responders if capillary P_CO2 was reduced by ≥10% after 1 h of HFJV. Data included peak inspiratory pressure, PEEP, capillary P_CO2 , and oxygen saturation index (equal to mean airway pressure × F_IO2 × 100/S_pO2 ). Because the data were not normally distributed, they are reported as median (interquartile range), and the Mann-Whitney test was used to assess differences in continuous data between groups. Categorical data were analyzed using a chi-square and Fisher exact test.

RESULTS

Thirty-four premature infants (n = 24 male) were studied. Twenty-five subjects were classified as responders and demonstrated a significant reduction of capillary P_CO2 and F_IO2 and increased pH within the first hour. The non-responders demonstrated a higher conventional ventilation peak inspiratory pressure (25 cm H₂O vs 19 cm H₂O, P = .005) and had a greater postmenstrual age (30 weeks vs 26.5 weeks, P = .01). This group had a higher oxygen saturation index (7.25 vs 3.36, P = .03) and F_IO2 requirements (0.6 vs 0.35, P = .038) at 4 h.

CONCLUSIONS

We identified that lower postmenstrual age, improvements in capillary P_CO2 and pH at 1 h, and a reduction of F_IO2 were associated with good response to HFJV. These data may help to identify patients who are likely to benefit from HFJV in the neonatal intensive care unit.

[The effects of pressure controlled ventilation for tracheobronchial foreign body removal in children]

Objective:To evaluate the effects of pressure controlled ventilation for tracheobronchial foreign body removal in children.Method: Ninety ASAⅡor Ⅲ children,aged 10 months to 3 yr,weighing 8-16 kg undergoing removal of airway foreign body were randomly divided into 3 groups(n=30 each):groupⅠpressure controlled ventilation(P)，group Ⅱ high-frequency jet ventilation(H),and group Ⅲ, reserve spontaneously breathings.Arterial blood gas analysis of Pre-operation and the end of operation,the occurrence of hypoxia during operation,the duration of operation,anesthesia emergence time and perioperative side effects were recorded. Result:The arterial blood gas analysis(PaO₂,PaCO₂,SaO₂)and SPO₂of Pre-operation in group P and H had no significant difference. The PaO₂ of the end of operations was significantly higher,and PaCO₂ was lower in group H. The occurrence of hypoxia during operation, the duration of operation,anesthesia emergence time and perioperative side effects in two group had no significant difference.Conclusion:The effects of pressure controlled ventilation and high-frequency jet ventilation for tracheobronchial foreign body removal in children were nearly the same,and pressure controlled ventilation can be commonly used in clinic.

A comparison of high-frequency jet ventilation and synchronised intermittent mandatory ventilation in preterm lambs

PURPOSE

Synchronised intermittent mandatory ventilation (SIMV) and high-frequency jet ventilation (HFJV) are accepted ventilatory strategies for treatment of respiratory distress syndrome (RDS) in preterm babies. We hypothesised that SIMV and HFJV both facilitate adequate oxygenation and ventilation but that HFJV is associated with less lung injury.

RESULTS

There were no differences in arterial oxygenation or partial pressure of carbon dioxide despite lower mean airway pressure during SIMV for most of the study. There were no consistent significant differences in end systolic and end diastolic PBF, lung injury data and static lung compliance.

METHODS

Preterm lambs of anaesthetised ewes were instrumented, intubated and delivered by caesarean section after intratracheal suction and instillation of surfactant. Each lamb was managed for 3 hr according to a predetermined algorithm for ventilatory support consistent with open lung ventilation. Pulmonary blood flow (PBF) was measured continuously and pulsatility index was calculated. Ventilatory parameters were recorded and arterial blood gases were measured at intervals. At postmortem, in situ pressure-volume deflation curves were recorded, and bronchoalveolar lavage fluid and lung tissue were obtained to assess inflammation.

CONCLUSIONS

SIMV and HFJV have comparable clinical efficacy and ventilator pressure requirements when applied with a targeted lung volume recruitment strategy.

Right pulmonary hilar pedicle injury secondary to blunt chest trauma in a child

Combined tracheobronchial and thoracic vascular injury in children following blunt trauma to the chest is potentially life-threatening and almost certain to be fatal unless managed promptly. We report one such incident where prompt identification and early aggressive surgical management prevented an almost certain fatal outcome in a 5-year-old girl with complete disruption of the right main bronchus just distal to the carina, and a tear in the right pulmonary artery.

Frequency dependence of lung volume changes during superimposed high-frequency jet ventilation and high-frequency jet ventilation

BACKGROUND

Superimposed high-frequency jet ventilation (SHFJV) has proved to be safe and effective in clinical practice. However, it is unclear which frequency range optimizes ventilation and gas exchange. The aim of this study was to systematically compare high-frequency jet ventilation (HFJV) with HFJV by assessing chest wall volume variations (ΔEEV(CW)) and gas exchange in relation to variable high frequency.

METHODS

SHFJV or HFJV were used alternatively to ventilate the lungs of 10 anaesthetized pigs (21-25 kg). The low-frequency component was kept at 16 min(-1) in SHFJV. In both modes, high frequencies ranging from 100 to 1000 min(-1) were applied in random order and ventilation was maintained for 5 min in all modalities. Chest wall volume variations were obtained using opto-electronic plethysmography. Airway pressures and arterial blood gases were measured repeatedly.

RESULTS

SHFJV increased ΔEEV(CW) compared with HFJV; the difference ranged from 43 to 68 ml. Tidal volume (V(T)) was always >240 ml during SHFJV whereas during HFJV ranged from 92 ml at the ventilation frequency of 100 min(-1) to negligible values at frequencies >300 min(-1). We observed similar patterns for Pa(O₂) and Pa(CO₂). SHFJV provided generally higher, frequency-independent oxygenation (Pa(O₂) at least 32.0 kPa) and CO₂ removal (Pa(CO₂) ∼5.5 kPa), whereas HFJV led to hypoxia and hypercarbia at higher rates (Pa(O₂) <10 kPa and Pa(CO₂)>10 kPa at f(HF)>300 min(-1)).

CONCLUSIONS

In a porcine model, SHFJV was more effective in increasing end-expiratory volume than single-frequency HFJV, but both modes may provide adequate ventilation in the absence of airway obstruction and respiratory disease, except for HFJV at frequencies ≥300 min(-1).

Bronchoscopy in the intensive care unit

The development of the flexible, fiberoptic bronchoscope has made bronchoscopic examinations possible in ICU patients undergoing mechanical ventilation. Over the years, the number of such procedures has greatly increased, with both diagnostic and therapeutic objectives, such as performing difficult intubation, management of atelectasis and hemoptysis, diagnosis of nosocomial pneumonia in ventilated patients, and early detection of airway lesions in selected situations, such as high-frequency ventilation. The complication rate can be kept low if the endoscopist has a precise knowledge of the many pathophysiological and technical facets particular to bronchoscopy under these difficult conditions. This article reviews some of these aspects, in the light of our personal experience.