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Patient-ventilator dyssynchrony.pptx
- 2. • Dyssynchrony is the effect of the patients respiratory demands not being appropriately met by the ventilator. The patient has their own idea about how to breathe, and the machinery supporting them, instead of making breathing easier, interferes with respiration and increases the work of breathing.
- 3. • PVA id defined mismatchimg between the patients breaths (neural) and ventilator assisted breaths and the inability of the ventilators flow delvery to match the patients flow demand.
- 4. Why is it bad..!! • The work of breathing increases: which is what you don't want with mechanical ventilation (remember, the point is to make breathing EASIER.) • Thus oxygen demand increases, tachycardia develops, and bad hearts get worse. • The patient becomes distressed (the experience of being dyssynchronous with one's ventilator resembles asphyxiation) • The patient begins to cough and/or vomit, which is a sub-optimal level of comfort. • Increases Hypoxemia and brotrauma, prolongs mechanical vemtilation and hospital stay in critically ill patients. • If there was an intracranial pressure problem, it will get worse with all this straining. Then, your nurse will bolus the patient with a massive amount of propofol, and their blood pressure will plummet, which does nothing to improve their cerebral perfusion.
- 6. Causes of patient-ventilator dyssynchrony • Wasted Effort: work of breathing increases because... – The mode is mandatory but the patient is awake and fighting the ventilator; • Effort is wasted when the patient tries to terminate a breath (straining to exhale against a closed expiratory valve) • Effort is wasted when the patient tries to initiate a breath (straining to inhale against a closed inspiratory valve) – The trigger is too high and the ventilator fails to supply gas when the patient demands it. – Inadequate level of support: the flow rate is too low and it does not meet patient demand. – The auto-PEEP is too high and the patient expends a lot of effort trying to defeat it • Auto-triggering: something other than the patient's respiratory effort initiates a breath, eg. cardiac oscillations • Double-triggering, premature breath termination: the ventilator delivers an inappropriately short breath, and the patient wants more air.
- 8. TYPES OF VENTILATOR DYSSYNCHRONY • hIneffective triggering – PEEPi (must generate enough effort to overcome PEEPi) – weaknessigh – incorrect ventilator settings – ventilator dysfunction • Inappropriate triggering (patient inspires while the ventilator cycles to expiration) – inspiratory time too short – inspiratory flow rate too low – set tidal volume low – coughing and hiccups • Autotriggering (important to distinguish from ineffective triggering) • Hiccups, coughing • cardiac oscillations • shivering • seizures • ‘rain out’ (condensation in ventilator circuit) • trigger sensitivity set too low • Flow dyssynchrony (too fast or too slow) • too slow: ‘pull down’ on pressure curve upstroke during inspiration • too fast : e.g. discomfort from rise time too short • Exhalation dysynchrony (too early or too late)
- 9. Factors that may Increase Respiratory • Hypoxemia, Hyp