There is a strong pathophysiological rationale for combining bronchoscopy and NIMV for the management of respiratory critical patients because the limitations of one technique may be counterbalanced by the properties of the other. In other words, NIMV may be of help in performing safe bronchoscopy in ARF patients, and FBO may increase the chance of success in patients at risk of NIMV failure.

ppNIMV is able to prevent and correct the cardiopulmonary alterations induced by bronchoscopy through three mechanisms: (1) compensation of the bronchoscope-correlated extra-resistive work of breathing by means of the unloading of respiratory muscles leading to a more favorable breathing pattern and diaphragmatic load-force relationship; (2) improvement of pulmonary gas exchange due to a better V/Q ratio and the correction of hypoventilation; and (3) counterbalancing of the increased heart workload by means of a marked relief of respiratory muscle effort with a reduced negative inspiratory intrathoracic pressure. Keeping the patient on ppNIMV after bronchoscopy may prevent the derangement of lung function that can last several hours after the procedure [6].

As a result of the clearing the airways in the early phases of ppNIMV, FBO may improve ventilation and, therefore, reduce the need for ETI in patients with an unfavorable balance between excessive burden of secretions and inefficient spontaneous clearance after the failure of chest physiotherapeutic techniques [6].

Three different acute scenarios of synergistic interaction between FBO and ppNIMV may be encountered in the ICU/RICU environment: (1) patients on O₂ therapy who undergo diagnostic FBO under ppNIMV assistance (for prevention of mandatory noninvasive or invasive ventilatory support in O₂-supported patients); (2) patients already on ppNIMV who undergo diagnostic FBO under ventilation (for prevention of CMV in ppNIMV-supported patients); and (3) patients requiring ETI for an excessive burden of bronchial secretions who undergo early therapeutic and diagnostic FBO during ppNIMV (as an alternative to mandatory CMV in ppNIMV plus FBO-supported patients) (Fig. 71.1).

The majority of the published studies have used ppNIMV to prevent respiratory deterioration in spontaneously breathing hypoxemic patients undergoing FBO who do not still require ppNIMV for ARF [6] (Table 71.2). Antonelli et al. [7] were the first to report on ppNIMV-assisted FBO; they performed BAL in eight immunocompromised patients with severe hypoxemia (PaO₂/FiO₂ ≤ 100 mmHg) due to suspected pneumonia. The use of ppNIMV was associated with significant improvements in PaO₂/FiO₂ and SpO₂ during bronchoscopy. FBO with NPPV was well tolerated, and no patient required ETI. Two patients died 5–7 days after FBO from unrelated complications of the underlying illness. A causative pathogen was identified by BAL in all patients, and six of them responded to treatment and survived hospital admission.

In a subsequent study, Da Conceicao et al. [8] investigated the feasibility of ppNIMV-assisted FBO in a 10 COPD patients admitted to ICU for pneumonia with hypoxemic-hypercapnic ARF (PaO₂ = 53 ± 13 mmHg; PaCO₂=67 ± 11 mmHg). During FBO with ppNIMV, SpO₂ increased from 91 ± 4.7 % at baseline to 97 ± 1.7 %.9. There were no changes in PaCO₂ and PaO₂ during the hour following the end of procedure. FBO under NIPPV was performed without complications and was well tolerated in 8 patients. No patient required ETI within 24 h, and all patients survived.

In the first randomized controlled trial (RCT), conducted on 30 patients with PaO₂ ≤ 125 mmHg despite high-flow oxygen mask (i.e., 10 l/min) requiring diagnostic FBO, Maitre et al. [9] showed significantly higher SpO₂ values during FBO and 30 min thereafter with CPAP, compared with oxygen-therapy, using a new device open to the atmosphere (CPAP Boussignac). Not only did the patients in the oxygen group develop hypoxemia during FBO, but 5 patients in the oxygen group (compared with none in the CPAP group) also required ventilatory assistance (1 ppNIMV and 4 CMV) within 6 h following the procedure (p = 0.003). A causative infectious agent was identified in 14 cases, with two diagnoses of carcinomatous lymphangitis (one by BAL and one by bronchial biopsy); fat embolism and drug-induced hypersensitivity pneumonia were diagnosed in 2 patients.

Subsequently, in another RCT involving 26 patients with nosocomial pneumonia and PaO₂/FiO₂ ≤ 200 mmHg, Antonelli et al. [10] evaluated the effectiveness and safety of ppNIMV versus conventional oxygen supplementation before, during, and after diagnostic FBO. Application of ppNIMV was associated with increase in PaO₂/FiO₂ by 82 %, in contrast to a decline in PaO₂/FiO₂ of 10 % in the oxygen group during FBO. Furthermore, in the ppNIMV group, PaO₂/FiO₂ remained higher, heart rate was lower, and there was no reduction in mean arterial pressure in comparison with a 15 % decrease from the baseline in the control group 60 min after FBO. Eighteen patients had significant growth of a pathogen found in BAL fluid. One patient in the ppNIMV group and 2 patients in the control group required non emergency ETI. Four patients in the ppNIMV group and 7 patients in the oxygen group died from complications of their underlying disease 5–7 days after study entry. The same group also found the helmet for delivering NIMV to be safe in avoiding gas exchange deterioration in 4 hypoxemic patients [11].

Chiner et al. [12] evaluated nasal mask for delivering ppNIMV while the FBO was performed orally using a bite block sealed with an elastic glove finger in 35 patients with a mean PaO₂/FiO₂ of 168. A total of 35 bronchoaspirates, 21 PSB, 11 BAL, and 8 bronchial biopsies were performed. In contrast to other studies, patients developed hypoxemia during the procedure, with SpO₂ decreasing to 86 % during FBO, probably as a result of excessive mouth-air leaks during nasal NIMV. The clinical course was favorable in 66 %; there was a relatively high rate of need of CMV (11 % of the cases occurring 5 ± 4 days after FBO) and in-hospital mortality (33 % of the cases occurring 3 ± 2 days after FBO), mainly correlated with the underlying disease.

Heunks et al. [13] reported the use of a novel total face mask for delivering NIMV during diagnostic FBO in 12 hypoxemic patients (mean PaO₂/FiO₂ = 192 ± 23). The procedure was successful in all patients; in only 1 patient SpO₂ decreased to 86 % during FBO. A microbiological diagnosis was established in 8 of 12 patients.