Pre-Fiberoptic Era Incidence of DLT Malposition
In the pre-fiberoptic bronchoscopy era, when double-lumen tubes were positioned using clinical assessment alone (auscultation and clinical signs), the malposition rate was approximately 39.5% to 45%, with a substantial proportion being critical malpositions that could affect patient safety.
Historical Context and Evidence
The evidence from the transition period when fiberoptic bronchoscopy (FOB) became available provides clear insight into pre-FOB era accuracy:
Malposition Rates with Clinical Assessment Alone
When DLTs were placed using clinical confirmation alone (the pre-FOB standard), up to 39.5% were found to be malpositioned when subsequently checked with bronchoscopy 1.
A prospective study of 200 patients found that in 172 cases where clinical assessment judged placement to be correct, fiberoptic bronchoscopy detected malpositioning in 79 cases (46%), with 25 of these (14.5%) being critical malpositions 2.
Another study comparing red rubber and PVC tubes found that clinical signs failed to detect significant malpositions, with the bronchial cuff not visualizable in 17 of 21 patients (81%), and 4 of 11 patients having left upper lobe orifice occlusion 3.
Specific Types of Malposition
Left-sided DLTs placed in the right main bronchus occurred in approximately 4.2% of cases, with increased likelihood in shorter patients, women, and when using smaller tube sizes 1.
After patient positioning to the lateral position, DLT displacement occurred in 93 of 200 patients (46.5%), with 48 of these (24%) being critical malpositions 2.
Tubes positioned "too deep" preventing carina visualization occurred frequently, and bronchial cuff overinflation causing right main bronchus obstruction was documented 3.
Clinical Implications
Why Clinical Assessment Failed
Clinical confirmation using auscultation has poor sensitivity and specificity for detecting DLT malposition 1.
Auscultation alone cannot reliably detect when the bronchial cuff is above the carina, when the tube is too deep occluding the left upper lobe, or when there is partial right main bronchus obstruction 3, 2.
Impact on Patient Outcomes
DLT malposition after lateral positioning was associated with a 59% incidence of further malposition during one-lung ventilation, compared to only 9% in correctly positioned tubes 4.
Patients with DLT malposition during one-lung ventilation required interventions (PEEP, CPAP, oxygen insufflation, or return to two-lung ventilation) in 84% of cases versus only 12% in correctly positioned tubes 4.
Two complications related to unsatisfactory lung separation were documented in the 200-patient prospective study 2.
Common Pitfalls in the Pre-FOB Era
The false sense of security from bilateral breath sounds and adequate oxygen saturation masked critical malpositions that would only become apparent during attempted lung isolation 2.
Right-sided DLTs were significantly more likely to be malpositioned than left-sided DLTs, yet this was not reliably detected clinically 2.
Patient repositioning from supine to lateral caused tube displacement in nearly half of cases, but this went unrecognized without bronchoscopic confirmation 2, 4.