mechanical ventilation in anesthesiology & cardiology ,nicvd,

7/27/2019 Mechanical Ventilation IN ANESTHESIOLOGY & CARDIOLOGY ,NICVD,

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TOPIC

MECHANICAL VENTILATION

SPEAKER

PROF. ABDUL KHALEQUE BEG

PROFESOR OF ANESTHESIOLOGY

NICVD, Dhaka.



MECHANICAL VENTILATION

Continue the process of ventilation

Controlled way

A period of time



Ventilation

Means exchange of air

Appropriately it means

Exchange of O2 & CO2



Who needs Mechanical Ventilation

Respiratory failure

Post surgical patients

Depressant drugs

Neuromuscular blocking drugs

Trauma

Unconsciousness

Metabolic disorders

Any disease process lead to respiratory failure



Breathing cycle constitute

One inspiration

One expiration



Minute volume (MV)

Respiratory rate (RR)

Times

Tidal volume (TV)



Main object of Mechanical ventilation

To resume adequate spontaneous breathing

To maintain physiological level of blood gas

PaO2 > 100 mmHg with an F102 0.5

PaCO2 < 40 mmHgPH > 7-35



How does a ventilator work ?

Electrically

Gas-driven

Preset volume of gas at a time Number of

times

Per minute

Preset flow

Preset pressure



Cycling Mechanism

Means repeating a cycle over and over again

Time cycling

Volume cycling

Pressure cycling



How to choose cycling Mechanism

Depending on the patients condition.



Basic mode of ventilation

Continuous Mandatory ventilation mode (CMV)

Preset respiratory rate delivered

Preset tidal volume delivered

Regardless of spontaneous inspiratory effort



Assist control (AC)

Preset tidal volume delivered synchronized

intermittent Mandatory ventilation (SIMV)

Volume emitted ventilation

Negative inspiratory effort presence

Extra breathes delivered by the machine

Patients makes an effort to breathspontaneously

Augments patients breathing weakness



Synchronized intermittent

Mandatory ventilation (SIMV)

Weaning from ventilation

Pt is fully recovered

Preset tidal volume

Pts own respiratory effort trigger the ventilator

Synchronized effort

Pt Machine initiated breath do not occur

simultaneously

Allow to recover gradually & improving the

respiratory effort.



Pressure support ventilation (PSV)

A preset maximum pressure is delivered

Pt initiated rate Pt can control rate and tidal volume

Great sense of control and comfort in a wake

Pt during weaning



Extended Mandatory Minute

ventilation (MMV)

Desired MV is set

If Pt attains this level spontaneously ventilator

does not give additional breaths

If not breath preset MV delivered



Who needs Mechanical ventilation

Respiratory failure

Post surgical pts

Depressant drugs

Neuromuscular blocking drugs

Trauma

Unconsciousness

Metabolic disorders

Any disease process lead to respiratory failure.



Respiratory system

Circulatory system

Check the heart rate and rhythm

Assess systemic perfusion

Assess postoperative bleeding Central nervous system (CNS)

Renal system

Gastrointestinal system Integument

Temperature



Recommended postoperative testsEvaluate the cardiorespiratory system with the

following: ABGs A CXR

An electrocardiogram (ECG)

An electrocardiogram (ECG)

Metabolic and hematologic evaluation can be performed

by clinical and blood chemistry analysis

ABG

Electrolytes

Urea nitrogen and creatinine

Glucose levels

Hemoglobin and hematocrit



Table-2. Initial ventilator settings for routine

postoperative cardiac patients.

F1O2: 0.7-1.0

Tidal volume: 12-15 ml/kg

Respiratory rate: 8-12 breaths/minPEEP: 5 cm H2O

Inspiratory-expiratory ratio: 1:2

Inspiratory flow rate: at least 30 L/min

PEEP = positive end-expiratory pressure.



Ventilator settings on arrival in the ICU:

F1O2 A tidal volume

A respiratory rate

Positive end-expiratory pressure (PEEP)

The initial inspiratory-expiratory (L/E) ratio Inspiratory gas flow rates

The mode of mechanical ventilation

Controlled ventilation

Assist control Synchoronized intermittent mandatory ventilation

Pressure support ventilation

Extended mandatory minute ventilation

Hemodynamic effect of mechanical ventilation



Table-3. The hmodynamic effects of mechanical

ventilation.

EffectMechanism Decreased cardiac outputIncreased intrathoracic pressureincreases right atrial pressure, decreasing venous return and right ventricular end-diastolic volume, thus decreasing right ventricular strokevolume.Leftward shift of the interventricular septum decreases left ventricular diastolic compliance, decreasing left ventricular end-diastolic volume andstroke volume. Increased PVRA tidal volume of 5-10 ml/kg increases PVR by

approximately 12% at end inspiration. Blood vessel compression and air spacedilation are responsible.Inaccurate PCWPHyperinflation with high tidalvolumes and PEEP of >12 cm H2O decrease the accuracy of PA catheter wedge pressure determinationsDecreased required O2 delivery Breathingnormally utilizes 5% of the toltal O2 consumption. In respiratory failure prior to mechanical ventilation, respiratory muscle O2 consumption may increase to50% of total O2 consumption. The cardiorespiratory requirements for this

increased O2 delivery are relieved with mechanical ventilation. NegativeinotropyA reflex vasodilation, bradycardia, and nagative inotropic effect mayoccur with lung hyperinflation and is directly proportional to tidal volume.

PVR = pulmonary vascular resistance; PCWP = pulmonary capillary wedge pressure;PEEP = positive end-expiratory pressure, PA = pulmonary artery.



=

Monitoring Postoperative cardic patients duringmechanical ventillatio

Arterial blood gases.

ETCO2

Pulse oximatry Mixed venous oxygen saturation

Withdrawing ventilatory support

Criteria to be filled prior to consideration for weaningand extubation

Hemodynamic



Table-4. Respiratory criteria for weaning from

mechanical ventilation and extubation.

Criteria for weaning from mechanical ventilation

PaO2 > 100 mm Hg with an F1O2 of 0.5

PaCO2 < 50 mm Hg

Arterial pH of > 7.32, unless cause clearly known and improvementexpected

PEEP < 5 cm H2O Stable chest x-ray

A wake without residual neuromuscular blockade

Criteria for extubation

Negative inspiratory force of at least – 20 cm H2O (preferably-30)

Vital capacity of at least 10 ml/kg (2-3 times the tidal volume) Resting minute ventilation of < 10 liters

Maximum voluntary ventilation > 2 times resting level

Patient is comfortable breathing spontaneously with CPAP of < 5 cm H2Owith respiratory rate < 30



Surgical hemostasis Adepuate neurologic function

No plannned intervention

Normothermia No acute changes shown on CXR

Satisfaction of the respiratory criteria

The weaning process

Withhold or minimize narcotics



Table-5. Methods of oxygen delivery to

the extubated patient

MethodO2 flow (L/min)Nasal cannulaFace tentFace

masksSimpleAerosolPartial rebreathing

Nonrebreathing1-6156-156-1525-4530-4535-6540-7060-8085-95



Conclusion

A mechanical ventilator is sophisticated deviceto manage patients with respiratory failure dueto any cause.

If proper setting are made and patients isclosely managed & monitored by skilled personals valuable lives can be saved.

Adequate knowledge of the subject,familiarity with the patients and machine and proper training in handling it is absolutelynecessary.

mechanical ventilation in anesthesiology & cardiology ,nicvd,

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