Tracheal and Esophageal Pressure Monitoring

Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Neil MacIntyre MD Duke University Medical Center Durham NC USA Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Two million Americans receive mechanical ventilation (MV) each year Avg duration is 6 days
Mortality depends on disease: ARDS 30-40%, COPD 20-30%, IPF 60-70% MV is supportive, not curative Goal is thus to support life without causing harm Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Challenges Gas exchange/O2 delivery vs VILI
Muscle unloading to avert fatigue AND VIDD
Synchrony to avoid sedation
Lung function vs other organs
Recognizing recovery Monitoring/testing focuses physiologic parameters Must be linked to outcomes an improvement in physiology may not necessarily be linked to an improvement in outcomes (and indeed the intervention that improves physiology may actually worsen outcomes) PEEP = 5 mbar Pinsp = 40 mbar (PEEP = 20 mbar) Balancing need for support vs distending pressures/FiO 2 Crs Crs also better in the HIGH Vt group also better in the HIGH Vt group Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Challenges Gas exchange/O2 delivery vs VILI
Muscle unloading to avert fatigue AND VIDD
Synchrony to avoid sedation
Lung function vs other organs
Recognizing recovery Monitoring/testing focuses physiologic parameters Must be linked to outcomes an improvement in physiology may not necessarily be linked to an improvement in outcomes (and indeed the intervention that improves physiology may actually worsen outcomes) Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Monitoring of the mechanically ventilated patient: Respiratory system mechanics
Neuromuscular function
Cardiovascular function What we will consider today: Blood, gas, or body fluid sampling amenable to POC testing Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid Blood gas analysis Role of arterial and venous sampling Gas exchange
Oxygen delivery/uptake Methodology Traditional laboratory measurements
Pulse oximetry
Transcutaneous
Gut tonometry Gas exchange PaO2 Goals are 55-80 torr
Must balance toxicities of ventilator pressure and FiO2 PaCO2/pH Goals are changing
Permissive hypercapnia to protect the lung Oxygen delivery DO2 = CO x (CaO2 CvO2) CO from indicator dilution, Fick, Doppler, exhaled gas (CO2, C2H2) Normal is 200-250 ml/min and 4 x VO2 (ie 25% extraction) When compromised, extraction can increase from 25% to 50%, then metabolism becomes anaerobic Metabolic acidosis, lactate buildup Blood gas analysis Role of arterial and venous sampling Gas exchange
Oxygen delivery/uptake Methodology Traditional laboratory measurements
Pulse oximetry
Transcutaneous
Gut tonometry Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid Other POC blood analyses Hemoglobin (O2 delivery)
WBC (inflammation)
BNP (cardiogenic edema)
Troponins CKs etc. (cardiac injury)
Creatinine/BUN (renal perfusion)
LFTs (liver perfusion)
Coagulation profiles (coagulopathies) Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid Exhaled gas analysis CO2 and O2 Capnometry
CO
VO2 Inert gases Insoluble gas dilution (lung volumes)
Soluble gas uptake CO, lung diffusion
MIGET for V/Q NO VO2 Total body oxygen consumption (and CO2 production) Guide nutrition
Muscle loading
Extraction ratio High is a normal response to demand outstripping delivery Low could mean high delivery OR impaired extraction (sepsis) Exhaled gas analysis CO2 and O2 Capnometry
CO
VO2 Inert gases Insoluble gas dilution (lung volumes)
Soluble gas uptake CO, lung diffusion
MIGET for V/Q NO Insoluble gas dilution Rebreathe or single breath hold of an insoluble gas Lung gas volume calculated from the dilution of a known inhaled volume of the
test gas Can also washout N2 with 100% O2 The intrabreath technique MIGET 6 gases with different solubilities infused
Exhaled gases analyzed for gas concentrations 50 unit lung model constructed from data to represent distribution of ventilation and
perfusion MIGET Exhaled gas analysis CO2 and O2 Capnometry
CO
VO2 Inert gases Insoluble gas dilution (lung volumes)
Soluble gas uptake CO, lung diffusion
MIGET for V/Q NO Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid Bronchoalveolar lavage (BAL) 60-120 ml NS instilled through bronchoscope (or special catheters) May also include brush Analyze for: Cell counts (Macs vs PMNs vs lymphocytes)
Cultures: >10 5 if PSB >10 3 if no PSB Monitoring Patients Requiring Mechanical Ventilation Present and Future POC Laboratory Tests Blood gases (lactate) arterial and venous
Other blood analyses
Exhaled gas analyses
Exhaled breath condensates
Bronchoalveolar lavage fluid

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