Ventilator Management

Question 0

What 7 factors contribute to ventilation perfusion mismatch and intrapulmonary shunting in the early postop period?

Answer 0

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

Question 1

What are the two principal mechanisms underlying poor gas exchange in the early postoperative period?

Answer 1

1. Ventilation/perfusion (V/Q) mismatch

2. Intra-pulmonary shunting

Question 2

Which ventilator mode reduces the use of analgesics and sedatives and often leads to a shorter duration of ventilator dependence?

Answer 2

BiPAP (beat out SIMV and A/C in trials)

Question 3

What is the normal range for minute ventilation immediately postoperative?

Answer 3

100 mL/kg/min

Question 4

How does immediate postoperative minute ventilation need to be changed for patients with COPD?

Answer 4

Lower respiratory rate, higher title volume, increased inspiratory flow rate (this reduces the risk for air trapping)

Question 5

What preop factors predict A prolonged need for mechanical ventilation? (13 answers)

Answer 5

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

Question 6

What are post operative predictors of the need for prolonged mechanical ventilation?

Answer 6

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

Question 7

Where is the respiratory center located in the brain?

Answer 7

Medulla oblongata

Question 8

What branches of the nervous system control bronchial constriction and bronchial dilation?

Answer 8

Sympathetic = dilation
Parasympathetic = constriction

Question 9

What criteria can the ICU nurse use to determine patient readiness for ventilator weaning? (6 criteria)

Answer 9

General physiologic stability
Hemodynamic stability
Pulmonary mechanics
Adequacy of gas exchange
Ability to breed spontaneously
Mental status

Question 10

What are the factors in general patient physiologic and hemodynamic stability that influence the success of weaning from mechanical ventilation?

Answer 10

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

Question 11

What factors in pulmonary mechanics influence the success of ventilator weaning?

Answer 11

Vital capacity
Minute ventilation
Respiratory rate
Tidal volume
Negative inspiratory pressure

Question 12

What are the two primary or underlying causes of failure to wean?

Answer 12

Failure of gas exchange at the alveolar level

Failure of ventilation

Question 13

What are some potential patient outcomes from an acidotic pH level?

Answer 13

Decreased myocardial contractility

decreased vascular response to catecholamines and

decreased response to the effect and actions of certain medications

Question 14

What are some potential patient outcomes from an alkaline pH level?

Answer 14

Interference with tissue oxygenation interference with normal neurologic function and normal muscular function

Question 15

What are some common causes of respiratory acidosis in the postop cardiac surgery patient?

Answer 15

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

Question 16

What are some common causes of respiratory alkalosis in the postop cardiac surgery patient?

Answer 16

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

Question 17

What are assessment signs of respiratory acidosis?

Answer 17

Warm flushed skin/bounding pulses/diaphoresis/tachycardia/dysrhythmias/central or peripheral cyanosis/pulmonary hypertension

Question 18

What is the treatment for respiratory acidosis?

Answer 18

Treat the cause of the underlying hypo ventilation and increase ventilation

Question 19

What are the assessment signs of respiratory alkalosis?

Answer 19

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

Question 20

What is the treatment goal for respiratory alkalosis?

Answer 20

Treat the underlying cause, relieve muscle fatigue, prevent acute respiratory failure

Question 21

What are some common causes of metabolic acidosis in the cardiac postop patient?

Answer 21

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

Question 22

What are the assessment signs of metabolic acidosis?

Answer 22

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

Question 23

What is the single underlying treatment for metabolic acidosis?

Answer 23

Restore tissue perfusion thereby preventing further hypoxemia

Question 24

What are common causes of metabolic alkalosis in postop cardiac patients?

Answer 24

NG suctioning / excessive diuretics /hypochloremia /hypokalemia /massive transfusion

Question 25

What are assessment signs and symptoms of metabolic alkalosis?

Answer 25

Dizziness/headache/G/delirium/seizures/weakness in creeping of muscles/tetany/respiratory depression/electrolyte imbalance, specifically: hypokalemia, hypocalcemia, hypomagnesemia, and hypophosphatemia

Question 26

What are some causes of high peak airway pressures?

Answer 26

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

Question 27

The ventilator alarms, indicating that the “f total” or respiratory rate has exceeded the high limit. What should the nurse assess?

Answer 27

Ventilator mandatory rate is set too high; patient has anxiety or pain; increased PCO2 level or secretions in the respiratory tubing

Question 28

The ventilator alarms, indicating “low V-TE” or low exhaled mandatory breath title volume. What should the nurse assess?

Answer 28

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

Question 29

Name factors contributing to a safe environment for the ventilated patient.

Answer 29

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!!

Question 30

What is the impact on the cardiovascular system from being on a vent?

Answer 30

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

Question 31

What are potential impacts on the renal system of patient being on a vent?

Answer 31

DECREASED:
Urine output, cardiac output

INCREASED:
ADH production

Question 32

What impact can being vented have on the hepatic and G.I. systems?

Answer 32

Decreased drug clearance from decreased cardiac output

at increased risk of bleeding stress ulcer

Question 33

Discuss some of the impacts of PEEP on the body systems.

Answer 33

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

Question 34

What is the typical range for PEEP settings?

Answer 34

5-20 cm H2O

Question 35

What is the highest risk when PEEP is weaned?

Answer 35

Rapid increase in venous return & preload, leading to flash pulmonary edema

Question 36

What are the signs and symptoms of a tension pneumothorax?

Answer 36

Increased peak pressures heart rate respiratory rate; decreased blood pressure; muffled breath sounds; tracheal deviation; sudden onset shortness of breath; chest pain; cyanosis

Question 37

What are assessment signs that show a patient is ready to wean from the ventilator?

Answer 37

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

Question 38

In a bilevel setting what is the usefulness of low peep and what is the usefulness of high peep?

Answer 38

Low peep is adjusted for oxygenation and high peep is adjusted for tidal volume