Pulmonary Disease

NFSC 470

McCafferty

Components of the Respiratory System

I. Drive Mechanism

II. Pumping Mechanism

III. Gas Exchange Organs

I. Drive MechanismA. Controls breathing patterns

B. Sensitive to hypoxia and hypercarbia

C. Modulated by the CNS1. Brainstem governs automatic respiration

2. Cerebral cortex controls voluntary breathing

II. Pumping MechanismA. Air flows in/out as volume of thoracic cavity

changes

B. Regulated by 3 groups of muscles:1. Diaphragm: major muscle for inspiratory

respiration. Moves up or down to lengthen or shorten cavity. (Inspiration: diaphragm contracts to increase volume of thoracic cage).

2. Intercostal muscles: internal & external muscles connecting ribs. Contract to pull ribs up and out to increase thoracic diameter

a. Major role in transition from inspiration to expiration

b. Provide major muscular work when demands for ventilation increase

3. Accessory muscles: elevate and stabilize chest wall at its largest diameter (once already “open”). Increases efficiency of diaphragm. Active during heavy breathing.

Also…

5. Chest wall assist with inspiration

6. Abdominals: used in active exhalation, ie. Exercise. Also role in inspiration

Inspiration is usually active – major role in pumping mechanism.

Expiration is usually passive.

III. Gas Exchange OrgansA. Upper airway (nose, mouth, pharynx)

conducts air and keeps out large particles

B. Lower airway (larynx, trachea, bronchi, bronchioles, alveolar ducts, and alveoli)

1. O2 thru alveolar membrane capillary membrane Hgb tissues

2. CO2 thru capillary membrane alveolar membrane through bronchial membrane exhaled

3. Alveolar membrane produces surfactant (PL): decreases surface tension and tendancy of collapse.

Functions of the Respiratory System

I. Gas exchange

II. Speech

III. Cardiovascular

IV. Metabolic Functions

I. Gas ExchangeA. Normal: 15x/min, 500 ml air, therefore

ventilate ~ 11000L air/dayB. ~6000 L blood moves through per day

C. ~600 L O2 in and 460 L CO2 removed

II. SpeechThoracic cage supplies exhaled air to voice apparatus (larynx)

III. CardiovascularNature of lung inflation affects pressure in thoracic cage; can affect heart i.e. pulmonary edema

IV. Metabolic FunctionsA. Surfactant production

B. Formation of angiotensin-converting enzyme (ACE)

C. Endothelial cells: produce SOD enzymes

Definitions

I. Partial Pressure: used to indicate the amount of any gas in the atmosphere, alveoli, or plasmaA. PCO2 Partial Pressure of carbon dioxide

1. Normal arterial blood values = 35-45 mm Hg2. Normal venous blood values = 41-51 mm Hg

B. PO2 Partial Pressure of oxygen 1. Normal arterial blood values = 80-100 mm Hg2. Normal venous blood values = 35-40 mm Hg

C. Arterial blood preferred: oxygenated, coming from the heart1. Gives idea of how things are throughout the body2. Gives idea of how well lungs have oxygenated the blood

Note: PCO2 measures respiratory status

↑ PCO2 means poor respiratory function

↓ PCO2 means hyperventilation

II. Respiratory Failure

A. Obstructive

B. Restrictive

Symptoms:

Effects of Respiratory Ds. On Nutritional Status

I. intake (see previous slide)

II. MedicationsSteroids (anti-inflammatory) cause protein catabolism, gluconeogenesis, muscle wasting and neg. N balance.

IV. Constipation/diarrheaChoice of low fiber foods (2’ dyspnea); poor peristalsis

2’ O2 to GI tract.

Respiratory Complications: Malnutrition

I. Established: A. respiratory muscle structure and fx.

B. ventilatory drive

C. pulmonary host immune defenses ( susceptibility to infections)

II. Proposed:A. surfactant production

COPD: Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease Slow, progressive obstruction of airways

Maj. Causes: tobacco smoke,

environmental pollution, genetic susceptibility

Emphysema: lung ds. characterized by

Pts present older, thin, mild hypoxemia but

NL HCT values. Cor pulmonale develops later

Cron. Bronchitis:

pts NL wt to ovrwt, hypoxemia and HCTCor pulmonale develops early.Cor Pulmonale:

MNT

Assessment: %IBW alone not sufficient; ongoing assessment of LBM

Kcals: replete but don’t overfeed!

Indirect calorimetry if possible: Kcal needs have been observed to range from 94% to 146% of predicted

Respiratory Quotient

Amount of CO2 produced/amount of O2 consumed…

For glucose: For fat: For protein: RQ for conversion of glucose to fat

Prot Preserve lung, muscle, and immune

fxTo preserve appropriate RQ: Prot: Fat: CHO:

Micronutrients Smokers :

Mg and Ca imp in muscle contraction/relax, Mg and Phos monitored

Poss vit D&K

Respiratory rehab: exercise, fluids, easily chewed diet w/adequate fiber GI motility

If experiencing bloating, decrease gaseous foods.

To intake

Prevent aspiration: TF to kcals in some pts (aspiration issues)

Issues of O2 use at nighttime (overnight feedings). O2 consumption decreases by 15%-25% during sleep.

Respiratory Failure

Causes: MODS

ARDS

Respiratory Failure, cont.

Pts. require O2 by nasal cannula or by mechanical ventilator.

Weaning from vent:

MNT: variesBody comp. fluctuation –