The integration of CO 2 and Flow provides an easy method to obtain previously difficult to obtain parameters
VCO 2 = CO 2 Elimination
Airway Deadspace, Physiologic V D /V T
Integration of Flow & CO 2 EtCO 2 Capnogram Respiratory Rate Capnography Volumetric CO 2 CO 2 Elimination Airway Deadspace Alveolar Ventilation Physiologic Vd/Vt
Phase I – Airway Gas The waveform is divided into three phases: The waveform begins at the onset of expiration. Imagine that you are the sensor sitting in the proximal airway. The first gas past the sensor at onset of expiration does not contain any CO2 but does have volume. The graph shows movement along the X-axis (exhaled volume) but no gain in CO2 (Y-axis). This volume is entirely from the conducting airways - no gas exchange has taken place. Phase I represents pure airway gas.
Phase II – Transitional Gas Phase II represents gas that is composed partially of airway volume and partially from early emptying alveoli (fast time constant). At about generation 17 of the airway tree we find alveolar units that communicate directly with the conducting airway and are considered fast time constant units. It is considered transitional gas (from airway to alveoli). An assumption is made here: 50% of phase II gas belongs to the airway and 50% belongs to the alveoli. Further research is needed to determine if this holds true in all clinical conditions (such as dramatically increasing PEEP).
Phase III – Alveolar Gas Phase III gas is entirely from the alveolar bed where gas exchange takes place.
Single Breath CO 2 Waveform EtCO 2 Exhaled Tidal Volume V D V ALV Z Y X
Ventilation Management Customize ventilator settings : VCO 2 (CO 2 elimination) reflects any changes in ventilation and/or perfusion; it indicates instantly how patient gas exchange responds to ventilator setting changes VCO 2 Vd/Vt MValv “ Noninvasively monitored VCO2 provides an instantaneous indication of the change in alveolar ventilation in mechanically ventilated patients. It allows instant, cheap and noninvasive determination of effective gas exchange.” Dynamics of Carbon Dioxide Elimination Following Ventilator Resetting. Varsha Taskar, MD ; Joseph John, MD ; Anders Larsson, MD,PhD ; Torbjörn Wetterberg, MD, PhD ; Björn Jonson, MD, PhD – Chest 108/1/July 1995 . .
Monitoring trends allows for detection of sudden and rapid in VCO 2 , without change in Alveolar Minute Volume or Tidal Volumes.
Drop in VCO 2 suggests change in blood flow to the lungs.
VCO 2 may be due to in C.O. or blood loss.
VCO 2 may be due to in C.O. or malignant hyperthermia.
Coupled with Alveolar Ventilation and Deadspace measurements, this allows for quick patient assessment.
Optimization of PEEP using VCO 2 /NICO CASE STUDY: Profile: 60 Yr. Male, History of COPD and cardiac problems, Admitted to ED with severe respiratory distress, elevated temperature and semi-comatose. Patient intubated and placed on control ventilation and monitored with NICO . Tidal Volume (6ml/kg)= 600 ml, Respiratory Rate=10, I:E=1:2, PEEP= 8 FiO 2 = 40%. Baseline CO = 4 L/min, Over time SpO 2 decreases from 94 to 88%. Flow/Volume loop and capnogram exhibit severe airway obstruction and increased work of breathing. Bronchodilator treatment administered and PEEP increased to 15 CmH 2 O. SpO 2 = 95%. Observed a decrease in VCO 2 (150 mL/m) and CO (2.5 L/m) due to increased intrathoracic pressure and decreased venous return. PEEP reduced to 8 cmH 2 O. Both cardiac output (3.4 L/m) and VCO 2 (225 mL/m) returns to baseline levels. Discussion: Use of NICO provided immediate and continuous feedback on the appropriateness of the ventilator strategy, and also allowed expeditious optimization of cardiac performance. PEEP=0 PEEP lowered to 4 cmH 2 O PEEP increased to 8 cmH 2 O
Initially, patient had a small amount of ventilatory support, but then was placed on a T-piece. The entire task of breathing was placed on the patient.
Within minutes trends showed that the patient was unable to support the required level of ventilation (VCO 2 decreasing since total Alveolar Ventilation is decreasing).
Spontaneous Tidal Volume trend also shows inadequate ventilation.
Removal of mechanical support, increased Vd/Vt, reducing ventilatory efficiency and the patient’s ability to remove CO 2 . This resulted in a pattern of rapid shallow breaths requiring the patient to be placed back on full mechanical support.
Designated Level 1 Trauma Center for Adults and Pediatrics
Associated with University of Tennessee Graduate School of Medicine
50+ Bed Level 3 NICU
70+ Bed Adult Critical Care
Operate Aggressive Therapist Driven Protocols on All Modalities of RC
Hospital Constraints Step Down Units created (sub-acute care) More severe ICU patient population Prefer Noninvasive technologies Pressure on hospital budgets Human resources limited Need to keep ventilator-time as minimal as possible Need to be efficient and costs
University of TN Medical Center Decrease of 39% Decrease of 12%
Reduction of Mechanical Ventilation Hours Using a Working Protocol with the Cardiopulmonary Management System Mikel W. O'Klock RRT, Dennis Harker RRT, Aksay Mahadevia MD, FCCP Genesis Medical Center, Davenport, IA. Reference: Respiratory Care, Dec 2005, Vol 50, Number 12, Page 95 Genesis Medical Center, Davenport, IA.
Genesis Medical Center (cont). Results: By incorporating the ventilation management protocol, the decision process was simplified for both physician and therapist. This resulted in a significant reduction (p=0.001) in mechanical ventilation hours per patient. Ventilator Hours Statistical Analysis 69 41,144 598 2004 118 72,492 612 2003 MVH/pt Total MVH Number of Patients Year
Genesis Medical Center (cont). Decrease of 42.2% Pre-NICO Post-NICO
Genesis Medical Center (cont). Pre-NICO Post-NICO
Continuous Monitoring Of Volumetric Capnography Reduces Length Of Mechanical Ventilation In A Heterogeneous Group Of Pediatric ICU Patients Donna Hamel,RRT, RCP,FAARC Ira Cheifetz, MD, FAARC; Pediatric Critical Care Medicine. Duke Children's Hospital, Durham, North Carolina Reference: Respiratory Care, Dec 2005, Vol 50, Number 12, Page 107 Duke Children's Hospital, Durham, North Carolina