Chapter 25: Pulmonary Disease

Question 1

Define inhalation.

Answer 1

An active process driven by a set of muscles that work in concert to bring air into the lungs

Question 2

Define expiration.

Answer 2

• Under normal circumstances, it is a passive process inw hich the diaphragm and intercostal muscles relax allowing the thoractic cavity to return to its normal resting state.
• In times of distress, primary and accessory muscles can aid in forced exhalation.

Question 3

Define hypercapnia.

Answer 3

CO₂ retention

• Can result from hypoventilation
• This situation, the patient may require noninvasive ventilator support, which involves positive airway pressure ventilation via an airtight mask (like CPAP), as well as, supplemental O₂.
• Common causes:
  
  • Obstructive pulmonary disease
  • Sleep apnea
  • Obesity leading to a collape of the upper airways (aka obesity hypoventilation syndrome)

Question 4

Explain Type 1 hypoxemic respiratory failure.

Answer 4

• Occurs when the partial pressure of oxygen (PaO₂₎ in arterial blood flow is less than 60 mmHg.
• AKA: This type is secondary to a failure of oxygen exchange and typically occurs at the level of the alveoli
• Mechanisms:
  
  • Diffusion defect (ie: underlying lung disease)
  • Ventilation-perfusion mismatch (ie: PNA)
  • Hypoventilation when it leads to low oxygen levels (ie: opiate intoxication)
  • Shunt physiology (ie: Severe ARDS)
• No matter the mechanism: Insufficient alveoli oxygen levels leads to reduced arterial hemoglobin oxygen saturation (SaO₂) and therefore reduced tissue oxygenation (HYPOXIA).

Question 5

Explain Type II hypercapnic respiratory failure.

Answer 5

• High body CO₂ levels, which occurs when the partial pressure of arterial carbon dioxide (PaCO₂) is elevated and causes blood pH to be less than 7.37.
• Hypercapnia occurs from either”
  
  • Too much CO₂ production through increased cellular respiration secondary to increased overall metabolic function OR,
  • Decreased alveolar ventilation causing decreased CO₂ gas exchanges
• Common causes:
  
  • Exacerbations of COPD
  • Opiate overdose
  • Chest wall defects
  • Decreased respiratory muscle function (r/t ALS or muscular dystrophy)

Question 6

Explain Type III Mixed Hypoxemic-Hypercapnic respiratory failure.

Answer 6

• Commonly encountered in the perioperative setting due to anesthesia.
• This form is always acute and frequently secondary to atelectasis (a complete or partial collapse of lung segments)

Question 7

Explain Type IV Shock-Related respiratory failure.

Answer 7

• Can be caused by:
  
  • Sepsis
  • Hypovolemia
  • Cardiogenic shock
• The presence of shock puts increased strain on the respiratory system and often subsequently leads to respiratory failure.

Question 8

What is the Berlin criteria/definition for ARDS?

Answer 8

• Acute Respiratory Distress Syndrome
• It is a potentially severe form of type I respiratory failure
• (1) Respiratory symptoms within 7 days of a known clinical insult (ie: PNA or sepsis), leads to
• (2) Bilateral lung opacities on chest radiograph or CT scan,
• (3) The respiratory failure and lung opacities are not explained by HF or fluid overload; AND
• (4) An oxygenation impairment is present, as defined by the ratio of PaO2 to FiO2, aka the P:F ratio

Question 9

What is the clinical criteria for mild ARDS?

Answer 9

• A P:F ratio (PaO2 to FiO2) is between greater to 200 mmHg and less than or equal to 300 mm

Question 10

What is the clinical criteria for moderate ARDS?

Answer 10

A P:F ratio (PaO2 to FiO2) is between greater to 100 mmHg and less than or equal to 200 mm

Question 11

What is the clinical criteria for severe ARDS?

Answer 11

A P:F ratio (PaO2 to FiO2) of less than or equal to 100 mmHg.

Question 12

What are common causes of ARDS?

Answer 12

• Direct Causes:
  
  • Gastric aspiration leading to PNA
• Indirect causes, include:
  
  • Sepsis, Trauma, and Acute pancreatitis

Question 13

Why is the exudative phase (0 to 7 days) so important when discussing ARDS?

Answer 13

• Associated with widespread lung inflammation and injury, which causes proteinaceous fluid to leak into the alveolar spaces, contributing to hypoxemia.
• Inflammatory mediators also induce a catabolic response culminating in protein breakdown.
• Consequatial diaphragmatic weakness places the patient at risk for PMV.

Question 14

**(TRUE/FALSE)

Based on high quality evidence, the SCCM/ASPEN 2016 nutrition therapy guidelines did make a recommendation regarding the routine use of an enteral formulation characterized by the anti-inflammatory lipid profile in patients with ARDS.

Answer 14

FALSE***

There is only low quality evidence, therefore SCCM/ASPEN did NOT make this recommendation.

Question 15

Define RR.

Answer 15

• Respiratory rate
• Frequency of respiration; the number of breaths delivered per minute

Question 16

Define TV

Answer 16

• Tidal Volume
• The volume of gas delivered during a breath

Question 17

Define minute ventilation.

Answer 17

The TV multiplied by the RR

Question 18

Define vital capacity.

Answer 18

The volume of change of the lung between full inspiration and maximal expiration

Question 19

Define lung compliance.

Answer 19

• The relationship of volume of gas and pressure of the lung (V/P)
• The lung’s ability to stretch and expand
• Diseased lungs frequently have poor compliance, which may increase the work of breathing.

Question 20

Define breath type (r/t MV modes)

Answer 20

Two types of breath are possible on MV

1. Mandatory breath: an assisted breath delivered by the mechanical ventilator based on the set RR
2. Spontaneous breath: may be assisted or unassisted and is a breath initially generated (triggered) by the patient.

Question 21

Define PEEP

Answer 21

• A positive pressure applied at the end of expiration during mechanical ventilation to prevent alveolar collapse and subsequent barotrauma

Question 22

Define volume control (in reference to MV)

Answer 22

The delivery of a predetermined inspiratory volume despite changing lung compliance or respiratory muscle activity

Question 23

Define pressure control (r/t MV modes)

Answer 23

• The delivery of a predetermined inspiratory pressure throughout inspiration despite changing respiratory muscle activity.
• The volume of gas delivered (TV) with this type of breath varies depending on the lung compliance.

Question 24

Define asthma.

Answer 24

A chronic inflammatory disorder of the airways, which leads to recurrent but reversible episodes of airway obstruction and is manifested clinically by chest tightness, coughing, wheezing and SOB

Question 25

Define COPD

Answer 25

• A common, preventable, and treatable disease, characterized by persistent airways limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lungs to noxious particles or gas
• 3rd leading cause of death in the US

Question 26

What is the BODE index used for? Explain what it is.

Answer 26

• Scale used to stage COPD according to degree of airflow limitation
  
  • B: BMI
  • O: Obstruction as assessed by FEV
  • D: Dyspnea as assessed by modified Medical Research Council score
  • E: Exercise capacity as measured by 6-minute walk distance.

Question 27

Define pulmonary cachexia syndrome.

Answer 27

• Malnutrition associated with advanced lung disease (such as COPD)
• Defined as a lean BMI of less than 17 in men and less than 14 in women

Question 28

Define interstitial lung disease (ILDs)

Answer 28

• A heterogeneous group of disorders that are classifed together because of similar radiographic, clinical and pathological manifestations
• ILDs cause lung restriction
• Numerous causes:
  
  • Occupational and environmental agents
  • Drug-induced etiologies
  • Radiation-induced etiologies
  • Connective Tissue disorders
  • Idiopathic causes
• ILDs commonly cause: Chronic Hypoxemix Respiratory Failure.

Question 29

Why can malnutrition be present with patients with CF?

Answer 29

Malnutrition from either pancreatic insufficiency or steatorrhea can be caused by malabsorption leading to nutrition deficiencies.

Question 30

(TRUE/FALSE)

BMI is an accurate measurement of nutritional status is patients with CF.

Answer 30

FALSE

Many patients do no reach their full growth potential, which means that BMI may not be as accurate

Question 31

How does the CMS define PMV?

Answer 31

Ventilator dependence for more than 21 days for at least 6 hours per day.

Question 32

Define chronic critical illness.

Answer 32

Defined as an ICU stay longer than 14 days with continued low-grade organ dysfunction.

Question 33

Define persistent inflammatory and immunocompromised catabolic syndrome (PICS).

Answer 33

Occurs in patients who survive acute critical illness and multiple organ failure, only to enter a state of chronic critical illness (after 14 days) characterized by low-grade organ dysfunction plus immune suppression with malnutrition, muscle weakness, recurrent infections, and poor wound healing.

Question 34

(FILL IN THE BLANK)

In patients with low nutrition risk, exclusive PN should be withheld during the first X days following ICU admission if the patient cannot maintain volitional intake and if early EN is not feasible.

Answer 34

• 7 days

Question 35

(FILL IN THE BLANK)

When EN is not feasible in patients determined to be high nutrition risk or severly malnourished, consider initiating exclusive PN XXXX days following ICU admission.

Answer 35

• As soon as possible

Question 36

(FILL IN THE BLANK)

In patients at either low or high nutrition risk, consider use of supplemental PN after X to X days if the patient is unable to meet >60% of energy and protein requirements by the enteral route alone.

Answer 36

• 7 to 10 days

Question 37

(FILL IN THE BLANK)

In appropriate patients requiring PN, consider hypocaloric pN dosing (which is?) with adequate protein (which is?) initially over the XXX of hospitalization in the ICU.

Answer 37

• < equal 20 kcal/kg/day or 80% estimated energy needs
• Adequate protein: >equal 1.2 g/kg/d
• First week

Question 38

If IC is not available, what equation should be used to estimate energy requirements for obese critically ill patients?

OR

For hypocaloric, high-protein regimen, what should you recommend?****

Answer 38

• Penn State University 2010 equation
• Less than 14 kcal/kg ABW with 1.2 to 1.5 g/kg ABW***

Question 39

Describe the pathogenesis of VAP.

Answer 39

• Ventilator-Associated PNA
• Difficult to determine, but it is thought to involve colonization of the oral pharynx, larynx, and upper esophagus with bacteria as well as microaspiration of secretions with bacteria.
• The placement of the endotracheal tube causes the trachea to be stented open and provides passage for secretions and bacteria into the lower respiratory tract.

Question 40

List some prevention strategies for VAP.

Answer 40

• If possible, avoid intubation by using noninvasive means of respiratory support
• Minimize sedation and analgesia as tolerated and needed for effective patient care, and if possible, provide a daily sedation vacation
• Maintain the patients physical conditioning through early mobilization and in-bed exercise
• Use continous subglottic suctioning to decrease pooling of oral secretions
• Elevate the head of the patient’s bed by more than 45 degree when possible
• Maintain the ventilator circuit by mniminizing changes to the circuit unless it is soiled or malfunctioning
• Decrease the patient’s time on mechnical vent if possible
• Provide oral care with chlorhexidine
• Consider probiotic use in select patient populations
• Limit broad spectrum abx

Question 41

(TRUE/FALSE)

Patients with ARDS are, however, frequently placed in the prone position because recent evidence suggests this position improves the outcomes for these patients. Enteral feeding is generally considered safe in the prone positition, but patients should be monitored closely for intolerance and aspiration.

Answer 41

TRUE.