Ventilator Management Flashcards
What 7 factors contribute to ventilation perfusion mismatch and intrapulmonary shunting in the early postop period?
Decreased Respiratory Drive following General anesthesia / mid sternotomy incision which produces Chestwall splinting / harvesting of the internal thoracic artery with plural entry / the effects of cardiopulmonary bypass / blood transfusion and potential for TRALI / pre-existing pulmonary comorbidities / phrenic nerve injury resulting in diaphragmatic dysfunction
What are the two principal mechanisms underlying poor gas exchange in the early postoperative period?
- Ventilation/perfusion (V/Q) mismatch
2. Intra-pulmonary shunting
Which ventilator mode reduces the use of analgesics and sedatives and often leads to a shorter duration of ventilator dependence?
BiPAP (beat out SIMV and A/C in trials)
What is the normal range for minute ventilation immediately postoperative?
100 mL/kg/min
How does immediate postoperative minute ventilation need to be changed for patients with COPD?
Lower respiratory rate, higher title volume, increased inspiratory flow rate (this reduces the risk for air trapping)
What preop factors predict A prolonged need for mechanical ventilation? (13 answers)
Presence of valvular disease / recent myocardial infarction / arterial hypertension / diabetes / previous cardiac surgery / chronic peripheral vascular disease / involvement of three or more vessels / surgical priority / elevated serum creatinine / age (>75 yo) / gender (female) / compromised LV function less than 40%EF / COPD
What are post operative predictors of the need for prolonged mechanical ventilation?
Hypoxia / decreased mentation / excessive intraoperative or post op bleeding / renal or cardiovascular failure / need for IABP / parenteral nutrition / inotropic therapy / acute respiratory distress syndrome (ARDS) / pulmonary edema / prolonged surgical or bypass time
Where is the respiratory center located in the brain?
Medulla oblongata
What branches of the nervous system control bronchial constriction and bronchial dilation?
Sympathetic = dilation Parasympathetic = constriction
What criteria can the ICU nurse use to determine patient readiness for ventilator weaning? (6 criteria)
General physiologic stability Hemodynamic stability Pulmonary mechanics Adequacy of gas exchange Ability to breed spontaneously Mental status
What are the factors in general patient physiologic and hemodynamic stability that influence the success of weaning from mechanical ventilation?
Presence of excessive bleeding Electrolyte imbalance: specifically phosphorus calcium magnesium and potassium Acid-base imbalance Volume overload Alterations in mental status Myocardial ischemia New onset dysrhythmia Need for vasopressors
What factors in pulmonary mechanics influence the success of ventilator weaning?
Vital capacity Minute ventilation Respiratory rate Tidal volume Negative inspiratory pressure
What are the two primary or underlying causes of failure to wean?
Failure of gas exchange at the alveolar level
Failure of ventilation
What are some potential patient outcomes from an acidotic pH level?
Decreased myocardial contractility
decreased vascular response to catecholamines and
decreased response to the effect and actions of certain medications
What are some potential patient outcomes from an alkaline pH level?
Interference with tissue oxygenation interference with normal neurologic function and normal muscular function
What are some common causes of respiratory acidosis in the postop cardiac surgery patient?
Poor muscle function from neuromuscular blocking agents
Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary edema or pulmonary embolism
Elevated CO2 from shivering or sepsis
Hypo ventilation caused by pain, sternal incision, residual anesthesia, impaired respiratory mechanics or opioid side effects
In appropriate ventilator settings
Hypo ventilation during bagging or transfer
What are some common causes of respiratory alkalosis in the postop cardiac surgery patient?
Hyperventilation from pain or anxiety
Increased demand for oxygen from fever or sepsis
Pulmonary edema or pneumonia
Medication causing respiratory stimulation
Inappropriate ventilator settings
Hyper ventilation during bagging or transfer
What are assessment signs of respiratory acidosis?
Warm flushed skin/bounding pulses/diaphoresis/tachycardia/dysrhythmias/central or peripheral cyanosis/pulmonary hypertension
What is the treatment for respiratory acidosis?
Treat the cause of the underlying hypo ventilation and increase ventilation
What are the assessment signs of respiratory alkalosis?
Lightheadedness dizziness agitation numbness or tingling in the extremities laryngospasm confusion blurred vision chest pain ischemic changes on the ECG peripheral vasoconstriction dysrhythmias and palpitations; dry mouth diaphoresis muscle twitching weakness tetanic spasm, some seizure
What is the treatment goal for respiratory alkalosis?
Treat the underlying cause, relieve muscle fatigue, prevent acute respiratory failure
What are some common causes of metabolic acidosis in the cardiac postop patient?
Decreased cardiac output/inadequate systemic perfusion/decreased cardiac function/decreased peripheral perfusion/hypotension/hypovolemia/vasoconstriction secondary to hypothermia/sepsis/renal failure/ischemia/diabetic ketoacidosis/anaerobic metabolism
What are the assessment signs of metabolic acidosis?
Headache/confusion/restlessness that progresses to lethargy/stupor/coma/Kussmaul respirations/cardiac dysrhythmias/decreased cardiac contractility with decreased cardiac output /hypotension/warm flushed skin/nausea and vomiting/insulin resistance/hyperkalemia
What is the single underlying treatment for metabolic acidosis?
Restore tissue perfusion thereby preventing further hypoxemia
What are common causes of metabolic alkalosis in postop cardiac patients?
NG suctioning / excessive diuretics /hypochloremia /hypokalemia /massive transfusion
What are assessment signs and symptoms of metabolic alkalosis?
Dizziness/headache/G/delirium/seizures/weakness in creeping of muscles/tetany/respiratory depression/electrolyte imbalance, specifically: hypokalemia, hypocalcemia, hypomagnesemia, and hypophosphatemia
What are some causes of high peak airway pressures?
Assess the need for suctioning; coughing; possibility of bronchial constriction or spasm; pneumothorax; condensation in the circuit; compressed circuit tubing; patient attempting to dislodge ET tube; tube advancement (main stemming); or decreased lung compliance
The ventilator alarms, indicating that the “f total” or respiratory rate has exceeded the high limit. What should the nurse assess?
Ventilator mandatory rate is set too high; patient has anxiety or pain; increased PCO2 level or secretions in the respiratory tubing
The ventilator alarms, indicating “low V-TE” or low exhaled mandatory breath title volume. What should the nurse assess?
Check for sources of error loss in the circuit including loose circuit connections, underinflated or incompetent ET cuff, or possibility of development of a pneumothorax
Name factors contributing to a safe environment for the ventilated patient.
All alarms are set and on
Never leave the bedside if alarms are in silence mode
Back up emergency equipment is readily available
Suction is set up and in working order
Patient is pre-and post oxygenated when suctioning
RT is available and can be contacted
Ventilator bundle order set and oral care interventions in place
When in doubt: Ambu bag the patient, page respiratory therapy, and have a plan in place to effectively ventilate the patient regardless of trach type!!
What is the impact on the cardiovascular system from being on a vent?
DECREASED:
Preload, cardiac output, blood pressure and end-organ perfusion
INCREASED:
Intrathoracic pressure, pulmonary vascular resistance (PVR), predisposition to dysrhythmias, DVT, incidence of barotrauma and volutrauma, O2 toxicity
What are potential impacts on the renal system of patient being on a vent?
DECREASED:
Urine output, cardiac output
INCREASED:
ADH production
What impact can being vented have on the hepatic and G.I. systems?
Decreased drug clearance from decreased cardiac output
at increased risk of bleeding stress ulcer
Discuss some of the impacts of PEEP on the body systems.
Alveolar recruitment –> pt can have lower FiO2 settings
Higher intrathoracic pressure –> decreased preload cardiac output blood pressure and urine output; increased PA pressures, ICP, and ADH levels
Can reduce pulmonary edema due to decreased preload
What is the typical range for PEEP settings?
5-20 cm H2O
What is the highest risk when PEEP is weaned?
Rapid increase in venous return & preload, leading to flash pulmonary edema
What are the signs and symptoms of a tension pneumothorax?
Increased peak pressures heart rate respiratory rate; decreased blood pressure; muffled breath sounds; tracheal deviation; sudden onset shortness of breath; chest pain; cyanosis
What are assessment signs that show a patient is ready to wean from the ventilator?
Hemodynamically stable
Adequate spontaneous inspiratory effort
Adequate oxygenation without mechanical support
Resolution of underlying pathology
Stable ABG results
Adequate level of consciousness - patient is able to follow commands and cooperate
In a bilevel setting what is the usefulness of low peep and what is the usefulness of high peep?
Low peep is adjusted for oxygenation and high peep is adjusted for tidal volume
