Presentation on theme: "“… an opening must be attempted in the trunk of the trachea, into which a tube of reed or cane should be put; you will then blow into this, so that the."— Presentation transcript:
“… an opening must be attempted in the trunk of the trachea, into which a tube of reed or cane should be put; you will then blow into this, so that the lung may rise again… and the heart becomes strong…” Andreas Vesalius (1555)
PS: Pressure Support. ◦ Set a pressure to deliver a Vt of 8 to 10 ml/Kg. ◦ patients often more comfortable since they have full control over their ventilatory pattern and minute ventilation. ◦ Should not be used in heavily sedated, paralyzed, or comatose patients. ◦ Respiratory muscle fatigue can develop if the pressure support is set too low.
A/C : Assist-Control Ventilation. ◦ Parameters set: VT RR FiO2 PEEP ◦ The ventilator delivers VT for all mandatory and spontaneous breaths. It assumes most/all of the work of breathing. Some patients may tend to hyperventilate on this mode.
SIMV / (PS): ◦ Parameters set: VT RR FiO2 PEEP PSV ◦ The ventilator will set up a window of opportunity for the patient to trigger a breath spontaneously and if they don’t or the time window elapses a mandatory breath will be delivered. Spontaneous breaths are supported with pressure support to decrease the work of breathing.
PCV: Pressure control Ventilation ◦ Parameters set: PC (Inspiratory pressure above PEEP) RR & (I:E) Ratio & Ti FIO2 PEEP ◦ The breath is pressure limited, not volume. ◦ Used more for ARDS patients. ◦ No guaranteed minute ventilation. ◦ Patients need to be sedated.
Liberation & Weaning ◦ More than half of all critically ill patients can be liberated successfully from mechanical ventilation after a brief trial of spontaneous breathing on the first day that reversal of precipitating factors is recognized. ◦ Gradual reduction of mechanical support, termed weaning, frequently is unnecessary and can prolong the duration of mechanical ventilation.
To wean or NOT to wean? ◦ Does the patient Need the airway, the ventilator, or both. Need oxygenation, ventilation, or both.
To wean or NOT to wean? ◦ A trial of spontaneous breathing.* A 30 min T-piece trial. A 30 min PS of 6 trial. ◦ Failure of an SBT is a clinical diagnosis. Rapid-shallow breathing, Tachycardia (>110 beats per minute). Hypertension (increment of more than 20 mm Hg). Mental status changes. Subjective distress. * Esteban A, Alia I, Tobin MJ, et al: Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation. Spanish Lung Failure Collaborative Group. Am J Respir Crit Care Med 159:512, 1999.
Analyzing Failure ◦ Airway assessment: Mechanisms of airway maintenance (e.g., cough, gag, and swallow) are sufficient to protect the airway from secretions. ◦ For short term airway, Wait. ◦ For long term airway, Tracheostomy.
Analyzing Failure ◦ Acute hypercapnia is due to imbalance of supply & demand. Demand: Fever, Sepsis, Overfeeding. Supply: Weakness, Increased resistance or decreased compliance. ◦ Rapid-shallow breathing is a sign of impending respiratory failure. ◦ Measure lung mechanics.
Analyzing Failure ◦ Measure lung mechanics. The RT do these measurements on A/C mode, Square flow waveform and 60 LPM flow. The patient must not be triggering the ventilator. Some patients may require sedation/paralysis for these measurements to be accurate. ◦ RAW(airway resistance)= (PIP-Plat)/Flow ◦ Normal across the tube 6-8 ◦ Normal airway resistance 5
Analyzing Failure ◦ Compliance is a change in volume for a change in pressure. (Vt/(Plat-PEEP)) ◦ Normal is 50ml/CmH2O ◦ Chest wall noncompliance. Abdominal distention, obesity, and kyphoscoliosis. Usually readily apparent by clinical examination. ◦ Lung noncompliance. Lung infiltrates, large pleural effusions, or dynamic hyperinflation.
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