Feasibility, safety, and utility of bronchoscopy in patients with ARDS while in the prone position.

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Prone positioning (PP) was shown to reduce mortality in mechanically ventilated (MV) patients with severe ARDS [1]. Despite its common use, safety concerns inhibit use of flexible bronchoscopy (FB) in patients with ARDS, and there are few reports of FB performed in PP [2]. We reviewed all adults receiving FB in PP in one institution between April 2016 and September 2017. The study was approved by the institutional review board. Four men and three women were identified (Table 1). In five patients, FB was indicated for clearance of thick secretions, and in two patients for microbial analysis. The mode of mechanical ventilation was not changed for FB, but FIO2 was universally set to 100%. All subjects had invasive hemodynamic and pulse oximetry monitoring. End-tidal carbon dioxide (EtCO2) was monitored in 3/7 subjects. With the subject’s head tilted to the side, the bronchoscope was advanced into the airways, repeatedly, and in short cycles, allowing time for oxygenation, ventilation, and lung recruitment between insertions. Therapeutic aspiration was performed in 6/7 subjects. Bronchoalveolar lavage was performed in two subjects. No significant hemodynamic compromise was observed during any of the procedures. Significant oxygen desaturation and rising EtCO2 were observed in one case (patient 4). Both derangements resolved with withdrawal of the bronchoscope and recruitment. No additional complications were documented. Figure 1 illustrates evolution of the PaO2:FIO2 ratio over time for each subject. Six subjects had antibiotics modified based on FB-obtained cultures. Consistent with previous data [3], 4/7 subjects survived 30 days following discharge from the ICU.

Table 1

Individual patient parameters, flexible bronchoscopy performance, and outcomes (n = 7)

Variable	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5	Patient 6	Patient 7
Age (years)	63	18	44	79	53	23	61
Sex	Female	Female	Male	Male	Male	Female	Male
Ethnicity	Black	Caucasian	Caucasian	Asian	Caucasian	Black	Caucasian
Etiology of ARDS	MRSA sepsis	Massive pulmonary embolism	Fulminant hepatic failure, Klebsiella sepsis	Pneumonia	Massive aspiration	Massive aspiration	Pneumonia
Total ICU LOS (days)/day of FB	27/9	30/13	97/32	35/29	9/2	49/11	16/1
Prone-positioning protocol (total hours)	28	18	16	236	20	133	18
30-day survival post ICU discharge	No	Yes	Yes	No	Yes	Yes	No
Ventilator-related parameters at FBa
Mode	PRVC	PC/AC	VC/AC	PRVC	VC/AC	PC/AC	PC/AC
Peak pressure (cmH2O)	32	29	24	37	30	20	32
Plateau pressure (cmH2O)	27	NA	NA	30	26	NA	27
PEEP (cmH2O)	11	12	15	8	10	10	14
FIO2 (%)	100	100	100	100	100	100	100
FB-related data
Δ-diameter ETT to bronchoscope (mm)	1.7	2.0	1.7	2.0	2.0	4.0	3.1
Therapeutic aspiration	Yes	Yes	Yes	No	Yes	Yes	Yes
Bronchial washings / BAL	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Monitoring data
MAP
Baselinea	69	67	87	68	72	67	80
Trough during FB	69	64	72	66	71	67	68
SpO2
Baselinea	94	98	97	100	100	100	100
Trough during FB	94	92	97	87	99	99	100
EtCO2
Baselinea	48	30	NA	43	NA	NA	NA
Trough during FB	49	30	NA	51	NA	NA	NA
Change in antibiotic regimen based on culture results	De-escalation	De-escalation	No	Additional coverage	De-escalation	De-escalation	De-escalation

ARDS adult respiratory distress syndrome, ICU intensive care unit, LOS length of stay, FB flexible bronchoscopy, MRSA methicillin-resistant Staphylococcus aureus, PRVC pressure-regulated volume control, PC/AC pressure-cycled assist-controlled, VC/AC volume-cycled assist-controlled, PEEP positive end-expiratory pressure, ETT endotracheal tube, BAL bronchoalveolar lavage, MAP mean arterial pressure as measured with an arterial line, NA not available, SpO oxygen saturation as measured with pulse oximetry, EtCO end-tidal carbon dioxide,FIO fractional concentration of inspired oxygen

aAs documented prior to first bronchoscope insertion

Fig. 1

Evolution of PaO2 to FIO2 ratio from pre bronchoscopy (T1) to 24 h (T2) and 72 h (T3) post bronchoscopy (n = 7). IQR interquartile range, PaO2 partial pressure of arterial oxygen, FIO2 fractional concentration of inspired oxygen

Although PP is lung-protective, it may result in mobilization of secretions into the airways, impairing oxygenation and providing nidus for infection [4]. Despite documented risks [5], FB may be beneficial in this situation.

Several limitations need to be addressed when interpreting our data. This is a retrospective analysis. Although physiologic monitoring was automatically captured, ventilator data were not and ventilator output during FB could not be accurately analyzed. Additionally, EtCO2 was not measured in all cases during FB. Finally, PP was shown to reduce mortality in patients with moderate to severe ARDS, however, our study subjects’ oxygenation had started to improve by the time FB was performed (Fig. 1, T1). This likely reflects reluctance to perform FB in subjects with severe hypoxemia due to excessive risks.

Our report demonstrates the feasibility of FB performed in brief increments in carefully monitored patients with ARDS ventilated in PP. Further studies are needed to better delineate optimal ventilator management during FB in PP.