Traqueobronquitis asociada al ventilador (TAV), implicancias del diagnostico clinico y microbiologico en una cohorte de pacientes en ventilacion mecanica / Ventilator associated tracheobronchitis (VAT), implications of clinical and microbiological diagnosis in a cohort of mechanical ventilated patients

RESUMEN

Tratar con antibioticos una TAV, proceso intermedio entre colonizacion y neumonia asociada al ventilador (NAV), reduciria la incidencia de NAV y sus consecuencias. Metodos: seguimiento clinico diario y cultivos cuantitativos rutinarios de aspirado traqueal (CRAT) bisemanales hasta el destete en 323 pacientes en ventilacion mecanica. Cuando se sospecho clinicamente infeccion (2/3 criterios), si habia infiltrado radiografico nuevo, se diagnostico NAV y se practico lavado broncoalveolar (LBA) y sin infiltrado nuevo, se diagnostico TAV, se consideraron los aislamientos del LBA positivos (¡Ý 104 unidades formadoras de colonias (ufc)/ml) para la NAV) y del CRAT positivos (¡Ý 103 y < 106 ufc/ml (bajo recuento) y ¡Ý 106 ufc/ml (alto recuento)) para TAV. Resultados: 443 de 2.309 radiografias mostraban ausencia de infiltrado o infiltrado difuso estable; 92 cumplian criterios de TAV, 13 de estas, 12 con CRAT ¡Ý 106 ufc/ml, tuvieron una NAV en los siguientes 3 dias (12 con cultivo de LBA ¡Ý104 ufc/ml). En estas NAV, 11/15 (73.3%) de los pat¨®genos coincidian con los de la TAV precedente. Desde otro punto de vista, 10 TAVs ocurrieron durante la semana posterior a una NAV, solo 4/12(33.3%) patogenos de estas coincidian con los de la TAV, p=0.045 comparando con TAV precediendo a NAV. Setenta TAVs no tuvieron relacion temporal con NAVs. Discusion: este estudio sugiere que tratar con antibioticos las TAVs podria prevenir una NAV en 14% de los casos, exponiendo a un uso innecesario al 86%, lo cual limitaria fuertemente la conveniencia de tratar las TAVs para prevenir las NAVs.

ABSTRACT

The ventilator associated tracheobronchitis (VAT) is a process between airway colonization and ventilator-associated pneumonia (VAP). The antimicrobial therapy of VAT wouldreduce the incidence of VAP and its consequences. Methods: Daily follow up and twice a week routine quantitative culture of endotracheal aspirates (CETA) up to weaning were performed in 323 mechanically ventilated patients.When a lower respiratory tract infection was suspected (2/3 clinical criteria), if a new radiographic inf¨ªltrate was present, VAP was diagnosed and a bronchoalveolar lavage (BAL) culture was performed; if a radiographic infiltrate was absent, VAT was diagnosed. The bacteriological criteria for diagnosis were a BAL culture positive (¡Ý 104 colony forming units - cfu/ml) for VAP and a CETA positive culture (low count from ¡Ý 103 to < 106 cfu/ml and high count ¡Ý 106 ufc/ml) for VAT. Results: In 443 of 2,309 radiographs an infiltrate was absent or was diffuse and stable; 92 of them met diagnostic clinical criteria for VAT. In 13 (12 with CETA culture ¡Ý 106 cfu/ml), a VAP episode happened during the following 3 days (12 with BAL culture ¡Ý 104 cfu/ml). In 11/15 (73.3%) VAP cases, the isolated pathogens were the same that had been present in the preceding VAT episode. On the other side, ten episodes of VAT were diagnosed during the 7 days after the VAP. Only 4/12 (33.3%) isolated pathogens were the same than those isolated in the VAT preceding the VAP, p=0.045. Seventy VATs had not any temporal relationship with episodes of VAP. Discusion: This study suggests that antimicrobial therapy could prevent a VAP in 14% of the TAV cases. Therefore, exposure to antibiotics was unnecessary in 86% of cases. This finding could represent a severe limitation to the recommendation of treating TAVs with antibiotics to prevent VAPs.