Functions of the upper airway

• Act as a conductor of air
• Humidify & warm or cool the inspired air
• prevent foreign materials from entering the tracheobronchial tree
• serve as an important area involved in speech & smell

Anatomy of the airway

Nose, oral cavity, pharynx & larynx

Anatomy of the lungs

Hemoglobin O₂ & CO₂ binding

Lung compliance and Resistance and Elastance

• How the body responds to increased/ decreased compliance and resistance

Ventilation-Perfusion relationships and Deadspace

• Causes of increased ventilation-perfusion ratio

Deadspace(is perfusion with little to no ventilation)

Increased V/Q (P_AO₂ rises & P_ACO₂ falls)

• Increase in ventilation
• Decrease in perfusion 1. P_ACO₂-decrease because its washed out alveoli faster than its replaced [increased RR] 2. P_AO₂- increased because it doesn't diffuse into blood as fast as it enters the alveoli & because the P_ACO₂ is decrease) seen in upper segment of upright lung

Ventilation-Perfusion relationships and Deadspace

• Causes of decreased ventilation-perfusion ratio

Decreased V/Q (P_AO₂ falls & P_ACO₂ rises)

• Decrease in ventilatio
• Increase in perfusion (1. P_AO₂ falls because O₂ is removed faster than it's replenished by ventilation 2. P_ACO₂ rises because CO₂ is removed out of blood faster than it it washed out of alveoli. seen in upper segment of upright lung

Oxygen dissociation curve

• What causes right shift

Right Shift (decreased affinity)

• Decrease in pH
• Increase in PaCO2
• Increase in temp
• Increase in 2,3 DPG

(2,3 DPG=diphoshoglyceric acid; end product of glucose metabolism; can bind Hb causing structure to change & decreasing affinity)

Oxygen dissociation curve

• What causes left shift

Left Shift (increased affinity)

• Increase in pH
• Decrease in PaCO2
• Decrease in temp
• Decrease in 2,3 DPG
• Hb Fetal
• COHb

Alveolar gas equation

PA_{0 2}=[PB - P_H2O] Fi_o2 - Pa_CO2 (1.25)

PA_{0 2}=[760 - 47] Fi_o2 - Pa_CO2 (1.25)

PA_{0 2}=[PB - P_H2O] Fi_o2 - Pa_CO2 (1.25)

Example:

=[755-47]0.40-55(1.25)

=[708]0.40-68.75

=[283.2]-68.75

=214.45

ABG Interpretation

pH 7.35-7.45 BE +2

PaCO₂ 35-45

PaO₂ 85-100

HCO^- ₃ 22-26

7.30/65/80/24/5 =uncompensated respiratory acidosis w/normal O2

7.50/38/60/34/3=uncompensated metabolic alkalosis w/mild hypoxemia

7.35/49/78/29/0= fully compensated respiratory acidosis w/mild hypoxemia

7.18/34/79/5/-10=partially compensated metabolic acidosis w/mild hypoxemia

Hemodynamic normals values

Central Venous Pressure

CVP

0-8 mm Hg

Hemodynamic normals values

Mean Pulmonary Artery Pressure

mPAP

9-18 mm Hg

Hemodynamic normals values

Pulmonary Capillary Wedge Pressure

Pulmonary Artery Wedge

Pulmonary Artery Occlusion

PCWP | PAW | PAO

4-12 mm Hg

Hemodynamic normals values

Cardiac Index

CI

2.5-4.2 L/min/m²

Hemodynamic normals values

Cardiac Output

CO

4-8 L/min

Hemodynamic normals values

Systemic Vascular Resistance

SVR

800-1500 dynes * sec * cm^-5

Hemodynamic normals values

Pulmonary Vascular Resistance

PVR

20-120 dynes * sec * cm^-5

Hemodynamic normals values

Right Atrial Pressure

RAP

0-8 mm Hg

Hemodynamic normals values

Stroke Volume

SV

60-130 mL

Hemodynamic normals values

Stroke Volume Index

SVI

30-60 mL/beat/m²

Hemodynamic normals values

Right Ventricular Stroke Work Index

RVSWI

7-12 g m/m²

Hemodynamic normals values

Left Ventricular Stroke Work Index

LVSWI

40-60 g m/m²

Hyperbaric oxygenation indications

HBO indications

• Gas embolism
• Burn patients
• Carbon monoxide patients
• Necrotizing infections such as gangrene

Effects of high altitudes on cardiopulmonary system

Barometric pressure & PO2 in the atmosphere decrease with altitude

body does several things to compensate (term is called- acclimatization)

8ways

• Increase in alveolar ventilation V.A (PAO2 decreases to 60mmHG)
• Polycythemia (increase in RBC low O2 over time)
• Acid Base status (PACO2 decreases because of increased ventilation causing respiratory alkalosis)
• Oxygen diffusion capacity (only with ppl who live in high altitude areas[mountains])
• PA-a difference [alveolar minus arterial] (oxygen diffusion is limited at high altitudes resulting in an increased PA-a difference)
• V/Q relationships (ratio improves because of increased pulmonary arterial BP)
• Cardiac output (with decreased oxygen in the environment it causes increased cardiac output)
• Pulmonary vascular system (decreased oxygen causes pulmonary vasoconstriction which leads to pulmonary hypertension)

Effects of high pressure on cardiopulmonary system

• Diving (for every 33ft below surface pressure increases by 1 ATM)
• Breath hold diving (a delicate balance between oxygen and CO2 levels exist)
• Hyperbaric medicine (patients are placed in hyperbaric chamber & O2 is administered while ambient pressure is increased) this increases tissue oxygenation