Adjunctive Care

In addition to standard ventilation care, during weaning, some interventions need further consideration.

Monitoring

A venous CO₂ threshold of below 45 mmHg is sensitive enough to reliable enough to exclude hypercarbia in lieu of sequential arterial samples [108]. If hypercarbia is detected, venous samples are insufficient to determine the degree of hypercarbia. End-tidal monitoring is less reliable. For end-tidal CO₂ to accurately reflect arterial CO2, lung perfusion levels and alveoli CO2 must be consistent throughout the lung, and TV must be at least three times the 2.2 mL/kg anatomic dead space [109]. As TV of 6 mL/kg is recommended, and CO₂ is unevenly distributed, the utility of end- tidal CO2 monitoring is limited.

Standard cardiac monitoring of vital signs and rhythm remains minimum requirements. More extensive cardiac monitoring is variable; many invasive processes to estimate cardiac performance have been withdrawn prior to weaning. Repeated echocardiograms may detect cardiac dysfunction during dys-synchrony, during weaning failure, or during the transition from controlled to spontaneous modes. Ultrasound may also detect undetected diaphragmatic dysfunction that contributes to delayed weaning [110].