Reason analysis of ineffective triggering caused by a continuous nebulization airflow in mechanical ventilation / 中华危重病急救医学

ABSTRACT

Objective? To? analyze? the? ineffective? triggering? caused? by? nebulization? in? the? way? of?respiratory?mechanics.? Methods? A?test-lung?and?an?oxygen-driven?jet?nebulizer?were?connected?to?the?circuit?in?a?PB840?ventilator.?The?test-lung?was?pulled?outwards?in?manual?way?till?an?inspiration?was?effectively?triggered?separately?in?different?flow-trigger?modes?[flow-trigger?sensitivity?(VTrig)?3?L/min?and?5?L/min]?and?pressure-trigger?modes?[pressure-trigger?sensitivity?(PTrig)?2?cmH2O?and?4?cmH2O,?1?cmH2O?=?0.098?kPa]?with?the?nebulizer?being?closed?and?opened?in?turn.?The?corresponding?relationship?and?characteristics?between?the?flow?and?pressure?in?the?circuit?under?different?triggering?conditions?were?observed?by?adjusting?the?curve?amplitude?in?the?screen.?The?minimum?alveolar?pressure?(Pa)?which?could?cause?an?effective?triggering?and?the?variation?span?of?Pa?during?the?triggering?period?were?analyzed?in?respiratory?mechanics.? Results? ①?In?flow-trigger?mode?Pa?was?pulled?down? from? positive? end-expiratory? pressure? (PEEP)? or? intrinsic? positive? end-expiratory? pressure? (PEEPi)? to?"PEEP－VTrigR"?(R?meant?airway?resistance)?without?nebulization,?and?the?span?of?Pa?was?"VTrigR"?or?"PEEPi－PEEP+VTrigR".?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP－(VTrig+N)?R"?(N?meant?nebulization?airflow)?with?nebulization,?and?the?span?of?Pa?was?"(VTrig+N)?R"?or?"PEEPi－PEEP+(VTrig+N)?R".?②?In?pressure-trigger?mode?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP－PTrig－1R"?without?nebulization,?and?the?span?of?Pa?was?"PTrig+1R"?or?"PEEPi－PEEP+PTrig+1R".?Pa?was?pulled?down?from?PEEP?or?PEEPi?to?"PEEP－PTrig－(N+1)?R"?with?nebulization,?and?the?span?of?Pa?was?"PTrig+(N+1)?R"?or?"PEEPi－PEEP+PTrig+(N+1)?R".? ?Conclusions? Nebulization?airflow?increases?the?difficulty?of?inspiratory?triggering?in?mechanical?ventilation.?PEEPi?makes?it?more?difficult.