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Introduction to Mech
Introduction to Mechanical Ventilation RCP 112
Question | Answer |
---|---|
What are the three indications for mechanical ventilation? | Ventilatory Failure oxygenation Failure Prophylactic Ventilatory Support |
What is the sandard criteria for instituting mechanical ventilation? | Apnea or absence of breathing Acute Respiratory Failure Impending Respiratory failure Refractory hypoxemia w/ increased WOB or ineffective pattern |
What is the criteria for acute ventilatory failure? | An increase of PaC02 >50 mm Hg with an accompanying respiratory acidosis (pH <7.25) |
What is the criteria for impending ventilatory failure? | Patient can maintain or marginally maintain normal ABG, but at the expense of significant WOB. PaC02 will trend upward. |
What are assessments that can indicate impending ventilatory failure? | Tidal volume Respiratory Pattern Minute Ventilation Maximul inspiratory Pressure Vital Signs |
What can be a secondary complication ventilatory failure? | Hypoxemia |
What is oxygenation failure defined as? | Severe hypoxemia that does not respond to moderate to high (>60%) supplimental oxygen. |
Oxygenation failure is not a direct indication for mechanical ventilation "BUT" | mechanical ventilation is needed to support WOB associated with oxygenation Failure |
Mechanical ventilation is indicated typically if the Pa02 | is <70mm Hg on 60% fi02 or <40 mm Hg on any fi02. P(A-a) of > 450 mm Hg on 100% fio2 |
Prophylactic ventilatory support is provided in clinical situations where there is risk of | pulmonary complications ventilatory failure oxygenation failure is high |
Prophylactic ventilatory support reduces | risk of pulmonary complications risk of hypoxia on major organs WOB and oxygen consumption Cardiopulmonary stress |
Hyperventilation therapy (blowing of c02) | decreases ICP |
What are the three conditions leading to mechanical ventilation? | Depressed respiratory drive Excessive Ventilatory Workload Failure of Ventilatory Pump |
Depressed Respiratory Drive (CNS) can include | drug overdose, acute spinal cord injury, head trauma, neurologic dysfunction, sleep disorders, metabolic alkalosis |
Excessive Ventilatory Workload (CNS) can include | acute airflow obstruction, deadspace ventilation, acute lung injury, congenital heart disease, cardiovasuclar decompensation, shock, increased metabolic rate, drugs, decreased complaince |
Failure of ventilatory Pump (NM/WOB) can include | chest trauma, premature birth, electrolyte imbalance, geriatric patients |
What is the absolute contraindication for mechanical ventilation? | Untreated pneumothorax |
What are three relative contraindications for mechanical ventilation? | Patients informed Request Medical Futility Reduction or termination of patient pain and suffering. |
What are hazards of mechanical ventilation related to positive pressure ventilation? | Barotrauma, hemodynamic instability, increased ICP, oxygen toxicity |
What are hazards of mechanical ventilation related to patient condition? | infection, multiple organ failure |
What are hazards of mechanical ventilation related to equipment | Ventilator or alarm malfunction, circuit disconnection, accidental extubation, endotracheal tube blockage, tissue damage, atelectasis |
What are hazards of mechanical ventilation related to medical professionals? | Nosocomial Infection, Inappropriate settings |
What are 2 things that affect the work of ventilatory muscles? | Compliance Resistance |
Compliance is defined as | the elastic forces of the lung |
Compliance is indirectly proportional with | ventilatory work |
compliance is directly porportional to | amount of volume inhaled |
Resistance is defined as | the force that must be overcome to move gas in and out of the lung |
resistance is directly proportional with | ventilatory work |
Resistance is indirectly proportional to amount of | voulume inhaled |
Poiseuilles Law goes along with resistance and states that there is | a 16 fold increase in airway resistance when the radius of the airway is decreased by half. |
What is the definition of a ventilator? | A machine/device that can fully or partially substitute for the ventilatory work. |
What are the 2 types of ventilators? | Negative Pressure Ventilators Positive Pressure Ventilators |
The iron lung encloses patient in tank except for the head and neck and works by | evacuating air to produce a negative pressure around the chest, which is transmitted to the lung. |
The greater the negative pressure the greater the? | volume moved into the lung |
What is andvantage of the iron lung? | noninvasive |
What are some disadvantages to the iron lung? | Poor Patient Access decreased cardiac output (tank shock) Requires added oxygen therapy |
The Chest Cuirass is also known as | the turtle shell |
Why was the chest cuirass created? | To improve patient access and minimize tank shock |
The chest cuirass covers the chest only and must have? | an airtight seal between shell and chest wall |
The chest cuirass works similar to the iron lung in that it generates | a negative pressure that is transmitted to the lung |
What is the advantage of the chest cuirass? | It's noninvasive |
What are disadvantages to the chest cuirass? | An airtight seal between patient and shell is difficult. Requires added oxygen therapy |
What are four physical characteristics of a mechanical ventilator? | Power source/ input power type of ventilator power transmission and conversion system. Control systems and circuits |
The power source or input power can be | pneumatic, electrical or both "built in" batteries/air compressors |
The type of ventilator can be either | Negative or positive pressure |
In regards to the power transmission and conversion system the drive mechanism is | the mechanism by which the ventilator transmits or converts the input power to useful ventilatory work. |
The Control panel is also known as the | user interface |
The control pannel allows for | the ability to manipulate pressure, volume, and flow; controls the drive mechanism |
The pneumatic circuit | is double lined and recognizes settings and sends signals |
Control variable corresponds with the | ventilator class |
Pressure controller | pressure does not change as a result of compliance and resistance changes |
Volume controller | volume does not change as a result of compliance and resistance changes |
A volume controller ventilator class measures volume | directly |
A time controller ventilator class is whereby | pressure, volume, and flow change as compliance and resistance changes. |
In a time controller ventilator class | time is constant |
In a flow controller ventilator class | volume does not change as a result of compliance and resistance changes |
in a flow controller class volume is measured | indirectly by measuring flow |
What is the average bias flow? | 6 lpm (flow that's always in the circuit) |
Phase 1 | change from expiration to inspiration |
Phase 2 | inspiration |
Phase 3 | change from inspiration to expiration |
Phase 4 | Expiration |
The trigger variable corresponds with Phase 1 and | triggers (starts) breath delivery |
The limit variable coressponds with phase 2 and | Is the variable not exceeded above the preset value during inspiration. |
It is important to note that inspiration does not end when | the variable reaches the preset value |
The Cycle variable corresponds with phase three and is | the variable that cycles (stops) the breath delivery) |
Expiration is | Passive and corresponds with phase 4 |
Ventilator Alarms can be | visual audible both |
Input Power alarms | warns loss of electrical or pneumatic power |
Control Circuit Alarms | Warns that settings are not acceptable or that ventilator has failed some part of self-diagnostic test |
Output (patient alarms) | Warns of problems with pressure, volume, flow, time, fi02, or circuit temperature problems |
Respiratory cycle time can also be called | Total Cycle Time |
Respiratory cycle time is calculated as | 60/Frequency |