Pulmonary function in normal subjects after bronchoalveolar lavage

The feasibility and safety of fiberoptic bronchoscopy during noninvasive ventilation in patients with established acute lung injury: another small brick in the wall

In hypoxemic patients needing fiberoptic bronchoscopy (FOB), noninvasive ventilation (NIV) has been used to prevent gas-exchange deterioration associated with FOB and to compensate for the increase in work of breathing occurring during FOB, thus avoiding endotracheal intubation and its related complications. The application of NIV to allow FOB has been found of particular interest in the diagnosis of pneumonia in patients spontaneously breathing and in those who started NIV to assist FOB. There is less information for patients who were already receiving NIV for acute respiratory failure and who were scheduled to undergo FOB. In the previous issue of Critical Care, the study by Baumann and colleagues adds new information to this specific issue, addressing the feasibility and safety of FOB during NIV in patients with established hypoxemic respiratory failure.

Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets

INTRODUCTION

Non-bronchoscopic bronchoalveolar lavage is an alternative to diagnostic bronchoscopy in pediatric patients, as fiberoptic bronchoscopes with aspiration channels are too large for small infants. There are many variations of the method in clinical practice, and saline instillation followed by open endotracheal suctioning is still commonly used. Lung function can deteriorate with these procedures, and we have investigated the effects on lung mechanics and oxygenation in healthy piglets.

METHODS

The lungs of anesthetized and mechanically ventilated piglets were recruited with CPAP 35 cmH2O. Thereafter we instilled 5 ml of saline into the endotracheal tube, followed by three breaths from the ventilator. Saline was retrieved through a suction catheter wedged far distally in the airway. The procedure was followed by a new recruitment maneuver. Complete inspiratory/expiratory pressure - volume loops (PV-loops) were obtained just before and 5 min after saline instillation. Arterial blood gases were collected at equivalent times in 14 similar piglets submitted to exactly the same procedure.

RESULTS

The inspiratory limb of the PV-loops changed markedly, as the lower inflection point was displaced towards higher pressures (P=0.004), and hysteresis measured at 15 and 30 cmH2O increased (P=0.004 and P=0.012, respectively). Although PaO2 decreased significantly (P=0.001), values after saline instillation/suctioning were still in the high normal range, that is, 22.2 +/- 2.6 kPa.

CONCLUSIONS

Opening pressures of the lungs increase markedly after saline instillation/suctioning in healthy piglets. In this situation, adequate recruitment maneuvers and PEEP might prevent lung collapse and deteriorations in arterial oxygenation.

Functional implications of BAL in the presence of restrictive or obstructive lung disease

Most of the complications associated to bronchoscopy are related to changes of the respiratory function during or after its performance. Prevention of complications should be achieved by understanding the effects of bronchoscopic procedures and their relation to the pulmonary function deterioration. Previous studies regarding the functional impairment caused by bronchoalveolar lavage (BAL) were mostly limited by the presence of interferent factors such as sedative drugs. Furthermore, it is not clear whether or not patients with different ventilatory disturbances present the same functional response to bronchoscopy and BAL. The aim of this study was to determine the additional effects of BAL over the respiratory function deterioration related to bronchoscopy in patients with different respiratory function profiles (normal, restrictive and obstructive). Forty patients submitted to bronchoscopy without premedication were divided into four groups: group I-normal pulmonary function submitted to basic bronchoscopy; group II-bronchoscopy in combination with BAL, subdivided according to pulmonary function: group IIa (normal function), group IIb (restrictive ventilatory disturbances) and group IIc (obstructive ventilatory disturbances). Spirometry was made before and after the bronchoscopic procedure. Baseline hemoglobin saturation was compared to the lowest level during the procedure. Functional worsening caused by the procedure was observed with a decrease in forced vital capacity (FVC), forced expiratory volume in the first second (FEV(1)) and Hemoglobin saturation in all groups. Comparison between groups showed no significant difference regarding the changes in FVC (P=0.8324), FEV(1) (P=0.6952) and hemoglobin saturation (P=0.5044). We conclude that standardized BAL, like the one used in our study, does not result in an increased risk for ventilatory impairment compared to bronchoscopy itself, independently of the presence of previous respiratory disease.

Bronchoscopy with bronchoalveolar lavage via the laryngeal mask airway in high-risk hypoxemic immunosuppressed patients

OBJECTIVE

Fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL) are major tools in the diagnosis of pulmonary complications in immunocompromised patients. Nevertheless, severe hypoxemia is an accepted contraindication to FOB in nonintubated patients. The purpose of this study was to evaluate the feasibility and safety of laryngeal mask airway (LMA)-supported FOB with BAL in immunosuppressed patients with suspected pneumonia and severe hypoxemia.

DESIGN

Prospective, clinical investigation.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Forty-six immunosuppressed patients admitted to our intensive care unit with suspected pneumonia and Pao2/Fio2 < or = 125.

INTERVENTIONS

After the administration of 0.3 mg x kg(-1) of etomidate, the patients were ventilated manually while receiving 1.0 Fio2. After the administration of 2.5 mg x kg(-1) of propofol, followed by an infusion of 9.1 +/- 2.3 mg x kg(-1) x hr(-1) of propofol, the LMA (size 3 or 4) was placed and connected to a bag-valve unit to allow manual ventilation with 1.0 Fio2. The FOB was introduced through a T-adapter attached to the LMA, and BAL was carried out with 150 mL of sterile 0.9% saline solution by sequential instillation and aspiration of 50-mL aliquots.

MEASUREMENTS AND MAIN RESULTS

Three patients developed transient laryngospasm during passage of the bronchoscope via the LMA, which resolved with deepening of anesthesia. Changes in mean blood pressure, heart rate, Pao2/Fio2, and Paco2 values induced by the procedure did not reach significance. Seven patients (15%) presented hypotension (mean blood pressure, <60 mm Hg) maintained for 120 +/- 40 secs, which required plasma expanders in three cases. Oxygen desaturation to <90% occurred in six patients (13%) during BAL. Nevertheless, the lowest Sao2 during the procedure was significantly higher than the initial Sao2 (94% +/- 4% vs. 90% +/- 2%). No patient required tracheal intubation during the 8 hrs after the procedure. BAL had an overall diagnostic yield of 65%. Because of the results obtained by using the BAL analysis, treatment was modified in 33 (72%) cases.

CONCLUSION

Application of the LMA appears to be a safe and effective alternative to intubation for accomplishing FOB with BAL in immunosuppressed patients with suspected pneumonia and severe hypoxemia.

[Fiberoptic bronchoscopy during noninvasive positive-pressure ventilation in patients with chronic obstructive lung disease with hypoxemia and hypercapnia]

OBJECTIVES

To assess the feasibility and safety of non invasive positive-pressure ventilation (NIPPV) via a face mask to performing fiberoptic bronchoscopy (FOB) in patients with COPD contraindicating FOB in spontaneous ventilation.

STUDY DESIGN

Clinical, prospective, open, non comparative trial of feasibility.

PATIENTS

Ten consecutive COPD patients (71 +/- 5 year-old, PaO2 = 53 +/- 13 mmHg and PaCO2 = 67 +/- 11 mmHg), without any sign of acute respiratory failure, admitted to the intensive care unit for pneumonia requiring a bronchoalveolar lavage (BAL). Including were: PaO2 < 70 mmHg despite nasal O2 delivered at 3 L.min-1, PaCO2 > 50 mmHg, improvement of SpO2 with NIPPV before FOB.

METHODS

Topical anaesthesia of the nose and pharynx was obtained with a 5% lidocaine spray. NIPPV was administered using a ventilatory support system Evita 4 (Dräger) applied through a full facial mask secured to the patient with elastic straps. Patients were first allowed to acclimate for 5 min with NIPPV (IPAP = 16 cmH2O, EPAP = 0 and trigger of 0.3 cm H2O while a FIO2 kept at 0.7). A T-adapter Medisize (Péters) was attached to the facial mask. The tip of the FOB was inserted through the nose. Topical anaesthesia of the vocal cords was obtained with 1% lidocaine solution (3 mL). The FOB was inserted into the trachea up to a bronchial sub-segment. BAL was performed by instillation of 100 mL of saline solution. After FOB, the NIPPV was maintained for 5 min. Heart rate, SpO2 were measured continuously and arterial pressure at 2 min intervals. Arterial blood gas values were obtained just prior NIPPV and after 15 min and 60 min NIPPV disconnection.

RESULTS

FOB duration was 11 +/- 4 min. SpO2 significantly improved during FOB (from de 91 +/- 4.7% to 97% +/- 1.7) without decrease of oxygen saturation lower than 90%. There were no changes in PaCO2 and PaO2 during the hour following the end of procedure. FOB under NIPPV was performed in all patients without complications and was very well tolerated in eight patients. After NPPV disconnecting, one patient required again NIPPV for 15 min. No patient required endotracheal intubation within 24 hours. All patients survived.

CONCLUSION

Application of NIPPV during FOB is a safe technic for maintaining adequate gas exchange in hypoxaemic and hypercapnic COPD patients not in acute respiratory failure. After the end of the procedure a close surveillance in the intensive care unit is essential.

[Diagnostic characteristics of acquired pneumonia in patients under mechanical respiration]

Ventilator-associated pneumonias (VAP) are the most frequent nosocomial lung infections. Histological diagnosis is the standard for reference. A diagnosis of VAP can be considered in presence of fever or hypothermia, hyperleucocytosis or leucopenia, worsening of blood gases, and new radiological infiltrate. Their diagnostical value is dependent on the number of included manifestations. A clinical pulmonary infection score (CPIS) has been produced and compared with histological data. Bacteriological data are essential for an adapted antibiotherapy. The blind non-protected specimen brush is inexpensive and reliable at levels of 10(4) and 10(6) CFU.mL-1, the sensitivity and specificity reach 60%. The double-protected catheter is a sensitive and specific test at the level of 10(3) CFU.mL-1. At present its accuracy has only been compared with bronchial brushing. The culture of a 20 mL mini-broncho-alveolar lavage (same material) is specific (50%) but not sensitive enough (< 70%) at the level of 10(3) CFU.mL-1. The culture of the protected telescopic brush is the most expensive test. It does not carry a risk of contamination, but does not detect a significant amount of VAP even at a level below 10(3) CFU.mL-1. Due to its high specificity it is used as the reference test in numerous studies. The endoscopic broncho-alveolar lavage provides a rapid diagnosis. Although not protected, it carries a low risk of false positives. It also allows the diagnosis of non-bacterial or atypical bacterial lung infections. The diagnosis can also be obtained with lung biopsy which however carries a risk in case of mechanical ventilation, whatever the technique. Except for the protected double catheter, a direct examination has been advocated, for the differentiation between infection and colonization and the improvement of the performances of the simple culture of the broncho-alveolar lavage (search for intra-cellular bacteria).

Effects of consecutive protected specimen brushing and bronchoalveolar lavage on gas exchange and hemodynamics in ventilated patients

OBJECTIVE

To assess cardiovascular effects and the oxygenation status of mechanically ventilated patients undergoing protected specimen brushing (PSB) and bronchoalveolar lavage (BAL) under fiberoptic bronchoscopy (FOB).

DESIGN

A prospective study.

SETTING

Polyvalent intensive care unit in a university hospital.

PATIENTS

Twelve consecutive, critically ill, intubated, and mechanically ventilated patients with hemodynamic failure requiring invasive monitoring with an indwelling radial artery catheter and indwelling Swan-Ganz catheter were included in the study.

INTERVENTIONS

Hemodynamic measurements, arterial and mixed-venous blood gas analyses, and arterial blood lactate analysis were performed before and at the end of a 10-min period of mechanical ventilation with a fractional concentration of oxygen in the inspired gas (FIO2) of 1.0. The same measurements and blood samplings were repeated at the end of the PSB procedure, at the end of the BAL procedure, and 1 h after the end of the BAL. During the study period the ECG, arterial oxygen saturation (SaO2), and mixed-venous oxygen saturation (SvO2) were continuously monitored.

MAIN RESULTS

A moderate increase in both mean arterial pressure and mean pulmonary arterial pressure was observed during the FOB procedure (p < 0.05). One hour after the end of BAL, the PaO2 decreased when compared with values recorded at the beginning of the procedure with the same FIO2 (p < 0.05). An increase in intrapulmonary shunt was observed at the end of BAL (p < 0.01). A moderate increase in PaCO2 was also observed after PSB (p < 0.05) and after BAL (p < 0.01). Monitoring of SaO2 permitted us to observe a significant and sustained decrease after the end of the FOB procedure from 10 to 60 min. The decrease in SvO2 was less pronounced but reached statistical significance.

CONCLUSIONS

We conclude that PSB and BAL under FOB are well tolerated in critically ill, mechanically ventilated patients with hemodynamic disturbances requiring inotropic or vasopressor agents (or both); however, a modest impairment in arterial oxygenation was observed after the end of the FOB procedure.

Sepsis syndrome and death after bronchoalveolar lavage

Bronchoalveolar lavage is widely used in the management of patients with interstitial lung diseases and is considered a safe procedure. We describe a patient who died with a picture consistent with acute pulmonary edema and septic shock following bronchoalveolar lavage. This potential complication has not been previously reported.

A reappraisal of blind bronchial sampling in the microbiologic diagnosis of nosocomial bronchopneumonia. A comparative study in ventilated patients

STUDY OBJECTIVE

To assess the usefulness of fiberscopy for microbiologic diagnosis of nosocomial bronchopneumonia (NBP) in ventilated patients.

DESIGN

Data were collected prospectively. We compared the results of semiquantitative cultures obtained by protected specimen brush (PSB), bronchoalveolar lavage (BAL) and blind bronchial sampling (BBS). Positive thresholds were 10(3) CFU ml-1 for PSB and BAL and 10(4) CFU ml-1 for BBS. We also evaluated the diagnostic performance of direct examination of samples obtained by BAL and BBS.

PATIENTS

We carried out this study in 64 ventilated patients admitted to a medico-surgical ICU.

RESULTS

During the study, 85 sets of samplings were obtained. The concordance between the results of specimen cultures obtained with the three techniques was 87 percent. The concordance between BBS and PSB or between BBS and BAL was 91.8 percent. In two of seven patients with discordant results between BBS and PSB, the microorganisms isolated from blood cultures were found on BBS, but not on PSB samples. As for direct examination, the thresholds for the diagnosis of NBP using BBS were as follows: > or = 10 polymorphonuclear neutrophils (PMN)/high-power field (HPF), > or = 1 bacteria/oil immersion field (OIF), presence of intracellular bacterial inclusions. Using BAL, the thresholds were as follows: > or = 1 PMN/HPF, presence of bacteria/OIF, presence of intracellular bacterial inclusions. The specificity of the presence of bacterial inclusions was excellent regardless of the sampling technique, but the sensitivity of this criteria was mediocre (30.8 percent with BBS and 19.2 percent with BAL). Except for the number of PMN on BBS, all the other diagnostic criteria (PMN count on BAL, bacterial count, count of cells exhibiting inclusions) provide a similar prediction of NBP (correctly classified: 61.2 to 81.2 percent). No combination of criteria enabled significantly better classification regardless of the sampling technique.

CONCLUSIONS

In view of these findings and the high cost and morbidity of fiberscopy, it is arguably better to use a simple, repeatable, and risk-free technique for obtaining culture specimens from mechanically ventilated patients. Obviously, protected brushing techniques remain the most effective for nonintubated patients.

Lung function and bronchial responsiveness after bronchoalveolar lavage and bronchial biopsy performed without premedication in stable asthmatic subjects

We evaluated tolerance, safety, and effects on lung function and bronchial responsiveness of BAL (4 x 50 ml) combined with BB (three to five specimens) performed without premedication in 13 mild and stable asthmatics and eight healthy volunteers. All subjects tolerated bronchoscopy procedures well and without serious side effects. During procedures, no supplemental oxygen was administered and no ECG abnormalities were noted. The PEFR was measured before and immediately after bronchoscopy and at 5-min intervals up until recovery. The maximal percentage fall in PEFR after bronchoscopy was significantly greater in asthmatics (23.1 +/- 13.9 percent) compared to normal subjects (7.8 +/- 8.2 percent, p less than 0.01). Changes in PEFR returned to baseline values within 120 min in all asthmatics. The tcPO2 was recorded at baseline, during and after bronchoscopy. In both groups, a significant change in tcPO2 was measured during the infusion of BAL aliquots, and persisted throughout the procedure. A significant difference in asthmatics compared to healthy subjects was evident during BB and at the end of the procedure (p less than 0.05). In asthmatics, M challenge was performed on three different days over a three-week period prior to bronchoscopy, and was repeated at intervals of 2, 6, and 24 h following procedure. The PC20 M values measured before bronchoscopy were found to have a very high reproducibility (intraclass correlation coefficient = 0.93). The PC20 values measured during experiment times after bronchoscopy were not significantly different from baseline values. These data demonstrate that in mild and stable asthmatics, BAL combined with BB can be safely performed following administration of only local anesthesia. In carefully selected asthmatic subjects, transient bronchoconstriction and a lowering of oxygen tension can be induced by BAL and BB, whereas changes in bronchial responsiveness are more unlikely to occur.

Bronchoalveolar lavage in immunocompromised patients. Clinical and functional consequences

Fiberoptic bronchoscopy and bronchoalveolar lavage are major tools in the diagnosis of acute pneumonia in immunocompromised patients. We conducted a prospective study to assess the morbidity associated with this procedure in 14 patients with AIDS and 16 patients with drug-induced immunosuppression. No patient had a PaO2 lower than 70 mm Hg with additional oxygen. Clinical data, chest roentgenogram, pulmonary function test, forced vital capacity, forced expiratory volume in one second, and arterial blood gases were recorded before and after bronchoscopy. Arterial oxygen saturation was monitored during the procedure, and initial, lowest, and final saturation values were noted. The patients were separated into three groups on the basis of chest roentgenographic findings. No procedure-induced pneumonia or need for tracheal intubation occurred. Minor clinical symptoms induced by the lavage in seven patients resolved spontaneously. By contrast, mean SaO2 decreased markedly during the procedure from 94 +/- 3 to 87 +/- 5 percent (p less than 0.0001) and returned to only 89 +/- 5 percent at the end of the procedure. Lowest SaO2 during the procedure and final SaO2 correlated poorly with initial SaO2 but correlated well with initial FVC and FEV1 (p less than 0.01). The PFT values were lower following bronchoscopy. O2 desaturation was more pronounced in patients with severe roentgenographic abnormalities. No significant differences were found between the three groups of patients, or between the AIDS and DII patients in terms of changes in PFT values. We conclude that in immunocompromised patients, bronchoscopy with BAL induces severe arterial oxygen desaturation which is correlated with initial PFT and chest roentgenographic findings, and most of these abnormalities are transient and do not lead to major complications.