biophysics_respiration_lecture.pptx karaganda medical University

Biophysics lectureeeeeeee

1. Topic: Intrapleural and intrapulmonary pressure. Inhalation mechanics. Exhalation mechanics. Respiratory work.

2. Complaints at the moment The patient complains: stabbing pain in the left chest a feeling of difficulty breathing a dry cough decreased tolerance to physical activity.

3. Anamnesis Vitae Name: P. Age: 32 Gender: M Occupation: Software Developer Lifestyle: Active Smoking: No Alcohol consumption: No Physical activity: Yes, 2 km jogging in the morning 3 times a week, powerlifting 2 times a week. Diet: Regular diet Allergies: No Previous diseases: No respiratory diseases in the medical history (asthma, COPD, no thoracic surgeries). Medication intake: No Recreational activities: Scuba diving at the sea coasts Vaccination status: Vaccines according to schedule

4. Anamnesis Morbi Main complaint: Sudden onset of shortness of breath and chest pain after scuba diving. History of the present illness: Two days ago, while scuba diving on the Caspian coast, a sudden sharp pain appeared on the left side of the chest . Symptoms: Weakness, dizziness. Increased pain with deep breathing or coughing, on the left side. Difficulty breathing.

5. Physical Examination results Cyanosis (bluish discoloration) present on the lips and fingertips. Cyanosis of the lips, tachycardia (without heart murmurs), body temperature is not elevated. Oxygen Saturation: Decreased (below 90%), The patient is breathing rapidly (RR 24\min). HR 87\min. BP: 110\70. Palpation: Asymmetry of the chest - when inhaling, the mobility of the chest on the left is reduced. Percussion: Hyperresonance on the left . Auscultation : Weakened breathing on the left

6. Arterial Blood Gases ( ABG ) Results for a Patient pH: 7.48 ( 7.35-7.45 -> slightly elevated, indicating respiratory alkalosis due to hyperventilation) PaCO ₂ (partial pressure of carbon dioxide): 32 mmHg (34-45 mm.Hg -> low , due to compensatory hyperventilation) PaO ₂ (partial pressure of oxygen): 55 mmHg (75-100 mm.Hg -> significantly reduced, indicating hypoxemia ) SaO ₂ (oxygen saturation): 86% (94-100 % -> decreased , correlating with hypoxemia )

7. Biophysics of respiration 1. Partial pressure of oxygen in atmospheric air (Dalton's law ). 2 . How does the chest shape and volume changes during inhalation ? 3 . Partial pressure of oxygen in the conduction zone 4 . Partial pressure of oxygen in the respiratory zone . 5 . How does air moves to the alveoli of the lungs (Boyle's law )? 6 . How does intrapulmonary pressure change during inhalation ? 7 . How does intrapleural pressure change during inhalation ? 8 . What factors affect intrapleural and intrapulmonary pressure ? 9 . What factors affect the magnitude of lung’s elastic recoil? What is the contribution of surface tension in lung’s elastic recoil? Which connective tissue protein is most important for lung’s elastic recoil, why ( Hooke’s law and Laplace's law )? 10. What are the laws governing the gas exchange process. How the diffusion rate is related to the difference in partial pressures on both sides of the blood-air barrier according to Fick's first law?

8. Pulmonary function tests Respiratory volume testing methods (spirometry, spirography ). During spirometry, just one measurement was performed, after which the patient complained of increased pain and cough. The examination was stopped. Result: VC - 3.5 l. Why are the values ​​of dynamic volumes (minute respiratory volume, FEV1, FVC, maximum ventilation of the lungs) important ? What parameters of external respiration indicate the presence of obstructive disorder? What parameters of external respiration indicate the presence of restrictive disorder?

9. Purpose : to measure volume of air inhaled/exhaled over particular respiratory maneuver Principle of operation (physical basis) : for open-circuit spirometry – instant air flow measurement with further integration over respiratory maneuver duration ; for water-sealed bell spirometer – volume measurement as a function of bell shift. Limitations: based on ability of the patient to follow doctor’s instructions Advantages : low cost (of equipment and single procedure), easy results interpretation Spirometry ( spirography ) Disadvantages : equipment requires calibration in the beginning of each day since equipment is sensitive to conditions in the room (temperature, humidity etc.), https://www.ncbi.nlm.nih.gov/books/NBK482339/ https://www.aafp.org/pubs/afp/issues/2020/0315/p362.html results are effort-dependent, there are possible deviation of measured values and procedure should be performed several times.

10. I nstrumental diagnostics What forces are directed at lung collapse? Elastic recoil of the lungs (Hooke’s law and Laplace's law). A lack of surfactant protein D? A disorder in the secretion of type II alveolocytes ? or A mechanical disorder in the distribution of intrapulmonary and intrapleural pressure? https://radiopaedia.org/cases/86926

11. Pneumothorax is a pathological accumulation of air in the pleural cavity, leading to a disruption of the ventilation function of the lungs and gas exchange during breathing.