Critical Care Pulmonary

What are the two types of pleura in the pulmonary system?

Parietal pleura lines the chest wall and visceral pleura lines the lungs

What is the role of the pleural space?

Provides lubrication for pleural movement and helps maintain lung expansion

What pressure is maintained in the pleural space to prevent lung collapse?

-5 cm H2O vacuum pressure

What type of cells compose 90% of the alveolar surface?

Type I alveolar cells

What is the function of Type II alveolar cells?

Produce pulmonary surfactant which decreases alveolar surface tension

What are the two types of alveolar cells?

Type I cells for gas exchange and Type II cells for surfactant production

What is the role of macrophages in the alveoli?

Remove debris and maintain lung sterility

What is ventilation?

Movement of air in and out of the lungs

What is perfusion?

Blood flow to the alveolar capillary membrane

What is diffusion?

Movement of gases from an area of higher concentration to lower concentration

What is the role of the alveolar-capillary membrane in gas exchange?

Facilitates oxygen and carbon dioxide transfer between alveoli and blood

What factors affect alveolar diffusion?

Surface area membrane thickness and gas solubility

How does carbon dioxide diffusion compare to oxygen diffusion?

CO2 diffuses about 20 times faster than oxygen

What is the effect of surfactant?

Decreases surface tension and helps prevent alveolar collapse

What can decrease alveolar surface area?

Injury lobectomy atelectasis or disease processes

What is a V/Q mismatch?

Imbalance between ventilation and perfusion

What characterizes a pulmonary shunt unit?

Perfusion without adequate ventilation

What characterizes a dead space unit?

Ventilation without adequate perfusion

What is the clinical relevance of the V/Q ratio?

Assesses efficiency of ventilation and perfusion

How is oxygen carried in the blood?

97% bound to hemoglobin and 3% dissolved in plasma

What does SaO2 represent?

Saturation of arterial blood with oxygen

What does PaO2 represent?

Partial pressure of oxygen dissolved in plasma

What is the primary indicator of oxygenation?

SaO2

What is the significance of SpO2?

Indirect estimate of SaO2

What is the relationship between ventilation and oxygenation?

Ventilation alone does not guarantee oxygenation

What is hypoxemia?

Low oxygen levels in the blood

What is hypercapnia?

High carbon dioxide levels in the blood

What are common symptoms of hypercapnia?

Headache drowsiness and altered level of consciousness

What does cyanosis indicate?

Late sign of severe respiratory distress

What parameters are measured in an ABG?

pH PaCO2 PaO2 SaO2 and HCO3

What is the normal pH range?

7.35-7.45

What does a pH less than 7.35 indicate?

Acidosis

What does a pH greater than 7.45 indicate?

Alkalosis

What is the normal PaCO2 range?

35-45 mmHg

What is the normal HCO3 range?

22-26 mEq/L

What is the normal PaO2 range?

80-100 mmHg

What does a PaO2 less than 80 indicate?

Hypoxemia

What does a PaO2 less than 60 indicate?

Critical hypoxemia

What does a PaO2 of 60 correspond to?

SaO2 about 90%

What does PaCO2 indicate?

Adequacy of ventilation

What does a high PaCO2 indicate?

Hypoventilation

What does a low PaCO2 indicate?

Hyperventilation

What regulates PaCO2?

The lungs

What regulates HCO3?

The kidneys

What is compensation?

The opposite system attempts to restore pH

What is correction?

The primary system returns pH toward normal

What disorder is present when PaCO2 matches pH?

Respiratory disorder

What disorder is present when HCO3 matches pH?

Metabolic disorder

What are signs of respiratory acidosis?

Low pH and high PaCO2

What are signs of respiratory alkalosis?

High pH and low PaCO2

How do kidneys compensate for respiratory acidosis?

Retain bicarbonate

How do kidneys compensate for respiratory alkalosis?

Excrete bicarbonate

What is an uncompensated disorder?

Opposing system has not responded

What is a fully compensated disorder?

pH is normal but PaCO2 or HCO3 remains abnormal

What is a mixed acid-base disorder?

Both respiratory and metabolic systems are abnormal

What is capnography?

Noninvasive measurement of exhaled CO2

ABG: pH 7.29 PaCO2 65 HCO3 24

Uncompensated respiratory acidosis

ABG: pH 7.32 PaCO2 60 HCO3 30

Partially compensated respiratory acidosis

ABG: pH 7.36 PaCO2 50

Fully compensated respiratory acidosis

ABG: pH 7.48 PaCO2 30

Respiratory alkalosis

ABG: pH 7.49 HCO3 38

Metabolic alkalosis

ABG: pH 7.48 HCO3 19

Respiratory alkalosis with partial compensation

What is the goal of oxygen therapy?

Optimize oxygenation using the least oxygen necessary

What percentage oxygen is room air?

21%

What is the flow range of a nasal cannula?

1-6 L/min

What FiO2 does a nasal cannula provide?

21-44%

What FiO2 can a high-flow nasal cannula provide?

21-100%

What oxygen concentration does a simple face mask provide?

40-60%

What is the purpose of a Venturi mask?

Deliver a precise oxygen concentration

What flow rate is used with a nonrebreather mask?

10-15 L/min

What FiO2 does a nonrebreather mask provide?

85-95%

What does CPAP stand for?

Continuous Positive Airway Pressure

What is the difference between CPAP and BiPAP?

BiPAP uses different inspiratory and expiratory pressures while CPAP uses one continuous pressure

What is the purpose of BiPAP?

Provides positive pressure during inspiration and expiration

What is the purpose of EPAP?

Keeps alveoli open and maintains alveolar pressure

What is the role of CPAP/BiPAP masks?

Improve ventilation and help eliminate CO2

What are nursing priorities for NIV?

Airway protection nutrition hydration oral care skin care and communication

Why should NIV patients not be restrained?

They must be able to remove the mask if vomiting occurs

What is a V60?

A device used for noninvasive ventilation

What is a common NIV complication?

Aspiration pneumonia

What is the purpose of intubation?

Secure the airway and ensure adequate ventilation

What is the recommended ET tube position?

2-3 cm above the carina

What confirms ET tube placement during intubation?

ETCO2 color change

What is the maximum intubation attempt time?

30 seconds

Why are daily chest x-rays obtained after intubation?

Verify ET tube placement

What does FiO2 stand for?

Fraction of Inspired Oxygen

What does PEEP stand for?

Positive End Expiratory Pressure

What is the purpose of PEEP?

Prevent alveolar collapse and recruit alveoli

What is the typical PEEP setting?

5 cm H2O

What complications occur with excessive PEEP?

Hypotension decreased venous return and lung injury

What happens when PEEP is decreased?

Alveoli may collapse

Which ventilator settings affect ventilation?

Tidal volume respiratory rate and pressure support

How does tidal volume affect CO2?

Larger tidal volumes eliminate more CO2

What ventilator change helps elevated PaCO2?

Increase respiratory rate

What ventilator change helps low PaO2?

Increase FiO2 or PEEP

What is Assist Control ventilation?

Preset breaths with additional patient-triggered breaths

What is SIMV?

Mandatory breaths with spontaneous breaths between

What is the advantage of SIMV?

Maintains respiratory muscle activity and aids weaning

What is Pressure Support Ventilation?

Provides pressure boost to spontaneous breaths

What is the role of pressure support during weaning?

Overcomes airway resistance