Pulmonolgy | Beehive Strong

Respiration at Rest:

* PaO2 100 mmHg Pulmonary vein (WNL)

* PaO2 40 mmHg Pulmonary artery

* Cardiac Output (Q): SV x HR = 5 L/min

* Low O2 demand

* Low CO2 production

* V/Q Ratio:

- Middle pulmonary aa ~ 0.8, basilar >0.8, apical <0.8

- V/Q ratio is higher when there is less perfusion, ultimately the trachea is considered dead space because of the non-existent perfusion. Inversely, shunt would be 100% perfusion, but no ventilation to the alveoli. In between is the ratios that are more closely considered.

- High V/Q = high oxygenation, low perfusion, less dilated pulmonary capillary sphincter.

- Low V/Q = low oxygenation, high perfusion, more dilated pulmonary capillary sphincter.

V/Q mismatch: units that are high and low, most common cause of hypoxemia (ie COPD, PE, pneumonia)

* The Low V/Q area typically has higher amounts of blood flow leading creating a stronger gradient in when mixed with highly saturated blood, ultimately decreasing the oxygenation of the blood returning to the L-atria.

*When higher amounts of FiO2% are given this creates an externally controlled bias towards better O2 blood saturation.

Respiration during Vigorous Exercise:

* PaO2 100 mmHg Pulmonary vein (WNL)

* PaO2 40 mmHg Pulmonary artery?

* Cardiac Output (Q): SV x HR = 30 L/min (6 x rest value)

* High O2 demand

* High CO2 production

Systemic Exercise Compensations:

Neurological Compensations:

1. Pulmonary Neural Drive via collateral axons of UMN - directly related to motor recruitment

Pulmonary Compensations:

Increased Tidal Volume
Increased Respiratory Rate

Cardiac Compensations:

Increased HR leading to increased Cardiac Output

Vascular Compensations:

Apical, middle, basilar ventilation perfusion ratio uniform conformity to about 80%
Occurs via pulmonary capillary sphincter dilation.
Small PaCO2 drive decreasing pH, shifting disassociation curve right -->

Figure 1:

https://erj.ersjournals.com/content/44/4/1023

Questions:

* How long does it take for stroke volume adaptations to occur?

* Mechanisms of pathology in pulmonary diseases?

Pathological Responses to Ventilation Perfusion Ratio: https://www.nature.com/articles/s41467-020-18672-6

https://journal.chestnet.org/article/S0012-3692(16)32900-2/fulltext

References:

https://pubmed.ncbi.nlm.nih.gov/20353492/

https://erj.ersjournals.com/content/44/4/1023 *****

Figures:

Stroke Volume: