Monitoring Ventilated Patients Dr.T.Sureshkumar MD, IDCCM, EDIC Consultant Intensivist Kovai Medical Center and Hospitals

SCOPE OF THIS TALK The aim is not to make anybody expert but to guide safe and efficient practice. Narrowed down to avoid major catastrophe Focused on graphics and hemodynamics as time limits Language is not a barrier here & I am not the best in English. My intention is not delivery but reach, so please come close to me.

Five Monitors Three Phases Patient Induction Ventilator Maintenance Vitals Images Labs Three Phases Induction Maintenance Weaning

Why Ventilation ?? Need for Ventilation Pulmonary Extra Pulmonary Abnormal lung Pulmonary Extra Pulmonary Normal lung Air way issues Parenchymal issues High resistance Poor Compliance

Start with…Intubation 1st - Look your Patient Look & check air entry Abnormal breathing Abdomen distending Irregular chest rise Hear Five point auscultation Abnormal sounds –wheeze, crepts And Yes your tube in right place…

Patient Disease worsening During Weaning : At induction phase Pt will be in control ventilation During maintenance Pt will trigger and may attempt his own breath Care should be taken whether he tolerates ventilator Our settings adequate for him Asynchrony Disease worsening During Weaning : Important to communicate with Patient Don’t ignore his needs

2nd – Check Ventilator Two important things What the ventilator gives to the patient How the lung accepts it.

Basic setup Scalars and loops Parameters Alarm settings Oxygenation ( FiO₂) Ventilation (RR, Vt) Desired mode Recruitment (PEEP) if needed. Scalars and loops Parameters Alarm settings

Ventilator Graphics Scalar and Loops are windows to Lung-Ventilation Mechanics So all modern ventilators equipped with Graphical representations. Gives a quick clue for problem even from a distance. On evaluation can diagnose specific disorder and helps in preventive measures.

Scalars and Loops: Scalars: Plot pressure, volume, or flow against time. Time is the x-axis. Loops: Plot pressure or flow against volume. (P/V or F/V). There is no time component.

Volume Modes Pressure Modes Pressure Control PRVC SIMV (PRVC) SIMV (Press. Control) Volume Control SIMV (Vol. Control) Pressure Support Volume Support

Pressure Time

Plateau Pressure Airway Pressure Mean airway Pressure

Increased Airway Resistance Decreased Compliance PIP PIP Raw Pplat Pplat •A -Increase in airway resistance (Raw) causes the PIP to increase, but Pplat pressure remains normal. •B-A decrease in lung compliance causes the entire waveform to increase in size. (More pressure is needed to achieve the same tidal volume). The difference between PIP and Pplat remains normal.

Air-Trapping (Auto-PEEP) •An acceptable amount of auto-PEEP should be < 5cm H2O

Flow Time

Volume Pressure

Wheeze & Bronchodilator Response Improved Peak Flow

The area of no flow indicated by the red line is known as a “zero-flow state”. This indicates that inspiratory time is too long for this patient.

Is it Inadequate insp. Time?? No . In spontaneous mode it is decided by the patient

Volume Time

Air-Trapping or Leak

Pressure / Volume loops Dynamic Compliance

Over distention/DHI

•As airway resistance increases, the loop will become wider. •An increase in expiratory resistance is more commonly seen.

Increased Compliance Decreased Compliance Example: Emphysema Example: ARDS, CHF, Atelectasis

Lung Compliance Changes and the P-V Loop Volume Targeted Ventilation Preset VT COMPLIANCE Increased Normal Decreased Volume (mL) Paw (cm H2O) PIP levels

Lung Compliance Changes and the P-V Loop Increased Normal Decreased VT levels Pressure Targeted Ventilation Volume (mL) Paw (cm H2O) Preset PIP

A Leak The expiratory portion of the loop doesn’t return to baseline. This indicates a leak.

Pressure / Volume Loop

The shape of the inspiratory portion of the curve will match the flow waveform.

A Leak Normal If there is a leak, the loop will not meet at the starting point where inhalation starts and exhalation ends. It can also occur with air-trapping.

Airway Obstruction

Flow Starvation The inspiratory portion of the pressure wave shows a “dip”, due to inadequate flow.

Hemodynamics Important to understand Thoracic physiology – Heart & Lung. Normally the Negative Plural Pressure augments the venous return to RA and thus increases CO So Output increases during Inspiration than Expiration. But in case of Positive Pressure it differs

The systolic pressure and the pulse pressure are maximum (SPmax and PPmax) during inspiration and minimum (SPmin and PPmin) during the expiratory period.

In hypovolemic conditions (1) RV preload decreases because the increase in pleural pressure induces a compression of the superior vena cava (2) an increase in intramural right atrial pressure (3) RV afterload increases because pulmonary capillaries are compressed. (4) The increase in alveolar pressure squeezes out the blood contained in the capillaries toward the left side of the heart. (5) The increase in pleural pressure induces a decrease in left ventricular afterload

In hypervolemic conditions The vena cava and right atrium are poorly compliant and compressible and hence relatively insensitive to changes in pleural pressure (4) Each mechanical breath increases pulmonary venous flow and left ventricular preload (5) The increase in pleural pressure induces a decrease in left ventricular afterload .

Capnography Measures End-tidal CO2 (EtCO2) Monitors changes in Ventilation - asthma, COPD, airway edema, foreign body, stroke Diffusion - pulmonary edema, alveolar damage, CO poisoning, smoke inhalation Perfusion - shock, pulmonary embolus, cardiac arrest, severe dysrhythmias Gold Standard for confirming Intubation Reports quality of CPR

Normal range is 35-45mm Hg (5% vol)

Waveform D C E B End-tidal Alveolar Plateau Ascending Phase of Exhalation A Descending phase of Inhalation E Baseline B

Normal 4 5 Hyperventilation 4 5 Hypoventilation

Normal Bronchospasm 4 5

SPO₂ Works at two different wavelengths absorbed by oxy and deoxy Hb and the gradient is used to calculate Hb saturation. Different models of probes available. Very useful to pick Pt deterioration. Pros : Mobile All time wearable Real time monitor Cheap Cons : Sats < 85 % are unreliable Impedance disturbances Picks little late Cannot measure MetHb, SulHb Altered with shock state, nail polish, dyes etc

CXR Useful for properly locating the ET Diagnosing issues. Follow Up of Disease.

ABG Its out of scope for this Session. Check Ph Metabolic side(HCO3) / Respiratory Side(PCO2) Compensated/ Uncompensated Any ventilator change can alter it.

Charting Even the best handing over cannot replace charting Reviewing trends helps in Pt Dx & Mx.

Language is not a barrier here & I am not the best in English.