Physiology of lung

1. Physiology of lung in health and illness Presented by: Ligi Xavier Second year MSc nursing Govt. College Of Nursing, Kottayam

2. Physiology of respiration inspiration- breathing in.. principle inspiratory muscles- the diaphragm & external intercostals. stimulation of diaphragm by the phrenic nerve diaphragm becomes tenses & flattens this enlarges the thoracic cavity& reduces its internal pressure

3. this force air in to the lungs other muscles also help-the scalenes fix the first pair of ribs while the external intercostal muscle lift the remaining ribs like bucket handles, making them swing up and out- this also forces air into the lungs. deep inspiration – is aided by the pectoralis minor, sternocleidomastoid, and erector spinae muscles.

4. expiration- passive process . It is achieved by the elasticity of the lungs and the thoracic cage- i.e., the tendency to return to their original dimensions when released from tension.

5. Lung volumes and capacities Lung  volumes  and  lung capacities  refer to the  volume  of air associated with different phases of the respiratory cycle. Lung volumes are directly measured; Lung capacities are inferred from lung volumes. The healthy adult averages 12 respirations a minute and moves about 6 liters of air into and out of the lungs while at rest.

6. Cntd .. tidal volume- the total amount of air moves into and out of the airways with each inspiration and expiration during normal quiet breathing. [ v T ][500ml] About 150 mL of it (typically 1 mL per pound of body weight) fills the conducting division of the airway. Since this air cannot exchange gases with the blood, it is called dead air, and the conducting division is called the anatomic dead space.

7. Physiologic (total) dead space- is the sum of anatomic dead space and any pathological alveolar dead space that may exist. In healthy people, few alveoli are nonfunctional, and the anatomic and physiologic dead spaces are identical. The total volume of air taken in during 1 minute is called the minute volume of respiration [MVR] or minute ventilation. It is calculated by multiplying the tidal volume by the normal breathing rate per minute.[500×12= 6000ml/ mt ].

8. The alveolar ventilation rate [AVR] is the volume of air per minute that reaches the alveoli.

9. Inspiratory reserve volume (IRV)[3,000 mL]:-Amount of air in excess of tidal inspiration that can be inhaled with maximum effort. Expiratory reserve volume (ERV)[1,200 mL]:-Amount of air in excess of tidal expiration that can be exhaled with maximum effort. Residual volume (RV)[1,300 mL]:-Amount of air remaining in the lungs after maximum expiration; keeps alveoli inflated between breaths and mixes with fresh air on next inspiration.

10. Vital capacity (VC)[4,700 mL]:-Amount of air that can be exhaled with maximum effort after maximum inspiration (TV + IRV + ERV); used to assess strength of thoracic muscles as well as pulmonary function. Inspiratory capacity (IC)[3,500 mL]:-Maximum amount of air that can be inhaled after a normal tidal expiration (TV + IRV). Functional residual capacity (FRC)[2,500 mL]:-Amount of air remaining in the lungs after a normal tidal expiration (RV + ERV)

11. Total lung capacity (TLC)[6,000 mL]:-Maximum amount of air the lungs can contain (RV + VC).

12. Pulmonary function tests Pulmonary function tests Pulmonary function can be measured by having a subject breathe into a device called a spirometer , which recap­tures the expired breath and records such variables as the rate and depth of breathing, speed of expiration, and rate of oxygen consumption. Four measurements are called respiratory volumes: tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Four others, called respiratory capacities, are obtained by adding two or more of the respiratory volumes: vital capacity, inspiratory capacity, functional residual capac­ity, and total lung capacity.

13. Spirograms and Flow Volume Curves  

14. Alveolar Surface Tension During breathing, the surface tension must be overcome to expand the lungs during each inspiration. It is also the major component of lung elastic recoil, which acts to decrease the size of alveoli during expiration.The surface tension of alveolar fluid is not as great as that of pure water due to the presence of a detergent-like substance called surfactant, produced by type 2 alveolar cells. Surfactant is a complex mixture of phospholipids and lipoproteins. It lowers the surface tension of alveolar fluid and thus reduces the tendency of alveoli to collapse completely.

15. Lung compliance It is the measure of the stretchability of lungs defined as the ratio of change in lung volumes to change in trans pulmonary pressure.lung resisting expansion at high volume. C= V P Normal value=200ml/cm of H 2 o

16. Compliance loop it is hysteresis loop in which the inspiratory compliance is less than that of expiratory compliance and loop is coming back to the same point of origin as we trace the compliance of full one respiration.

17. RESISTANCE TO AIRFLOW Flow = change in pressure/resistance (F = AP/R). Factors affecting Pulmonary compliance Diameter of the bronchiloes

18. Ventilation perfusion ratio V A almost equal to 0.8. mismatch usually seen in pulmonary embolism.

19. Patterns of breathing Apnea - Temporary cessation of breathing (one or more skipped breaths). Dyspnea- Labored, gasping breathing; shortness of breath. Eupnoea- Normal, relaxed, quiet breathing; typically 500 mL/breath, 12 to 15 breaths/min. Hyperpnea - Increased rate and depth of breathing in response to exercise, pain, or other conditions.

20. Hyperventilation- Increased pulmonary ventilation in excess of metabolic demand, frequently associated with anxiety; expels C0 2 faster than it is produced, thus lowering the blood C0 2 concentration and raising the pH. Hypoventilation- Reduced pulmonary ventilation; leads to an increase in blood C0 2 concentration if ventilation is insufficient to expel C0 2 as fast as it is produced. Kussmaul - Deep, rapid breathing often induced by acidosis, as in diabetes mellitus.

21. Orthopnea - Dyspnea that occurs when a person is lying down. Respiratory arrest- Permanent cessation of breathing (unless there is medical intervention). Tachypnea - Accelerated respiration  .

22. Gas exchange & transport External[pulmonary] respiration- it is the exchange of O 2 and CO 2 between air in the alveoli of the lungs and blood in pulmonary capillaries. It results in the conversion of deoxygenated blood coming from heart to oxygenated blood. factors that affect the efficiency of alveolar gas exchange:- concentration gradient of gases[ ie , po2 & pco2] Solubility of the gases Membrane area Ventilation-perfusion coupling.

23. Internal respiration exchange of oxygen and carbon dioxide between tissue blood capillaries and tissue cells called internal[tissue] respiration.it results in the conversion of oxygenated blood into deoxygenated blood. Oxygenated blood entering tissue capillaries has a pO 2 of 100 mm Hg, where as tissue cells have an average Po 2 of 40 mm of Hg. Because of this difference , oxygen diffuses from the oxygenated blood through interstitial fluid and into tissue cells until the pO 2 in the blood decreases to 40 mm of Hg

24. While oxygen diffuses from the tissue blood capillaries to tissue cells, carbon dioxide diffuses in the opposite direction.

25. Gas transport 1 . oxygen- The concentration of oxygen in arterial blood, by volume, is about 20 mL/ dL . About 98.5% of this is bound to hemo­globin and 1.5% is dissolved in the blood plasma.

26. Oxygen dissociation curve

27. 2. Carbon dioxide- a] About 90% of the CO 2 is hydrated (reacts with water) to form carbonic acid, which then dissociates into bicarbonate and hydrogen ions. B] About 5% binds to the amino groups of plasma proteins and hemoglobin to form carbamino compounds —chiefly, carbaminohemoglobin (HbCO 2 ). c] The remaining 5% of the CO 2 is carried in the blood as dissolved gas.

28. Arterial blood gas analysis An arterial blood gas (ABG) test measures the acidity ( pH ) and the levels of oxygen and carbon dioxide in the blood from an artery. This test is used to check how well lungs are able to move oxygen into the blood and remove carbon dioxide from the blood.

29. ABG values Partial pressure of oxygen (PaO2): Greater than 80 mm Hg (greater than 10.6 kPa ) Partial pressure of carbon dioxide (PaCO2): 35-45 mm Hg (4.6-5.9 kPa ) pH: 7.35-7.45 Bicarbonate (HCO3): 23-30 mEq /L (23-30 mmol /L ) Oxygen content (O2CT): 15-22 mL per 100 mL of blood (6.6-9.7 mmol /L) Oxygen saturation (O2Sat): 95%-100% (0.95-1.00)

30. Pulse oximetry A non invasive technolgy to monitor oxygen saturation of the haemoglobin

31. wavelength Extinction coefficient 660nm 940nm MetHb Oxy Hb Deoxy Hb COHB

32. Design of pulseoximeter 2 Wavelengths- 660nm [red] & 940nm[infra red] The ratio of absorbencies at these two wavelengths is calibrated empirically against direct measurements of arterial blood oxygen saturation (S a O 2 ) in volunteers, and the resulting calibration algorithm is stored in a digital microprocessor within the pulse oximeter . Led & photodetector Newer types of LED is based on aluminium gallium arsenide system Signal processed in the micro processor Senses only the pulsatile flow

33. PaO2 [mmHg] SaO2 [%] Normal 97 to ≥80 97 to ≥95 Hypoxia < 80 < 95 Mild 60-79 90-94 Moderate 40 – 59 75 – 89 Severe < 40 < 75

34. Uses of pulseoximetry Monitoring oxygenation During anaesthesia in ICU, PACU during transport Monitoring oxygen therapy Assesment of perfusion Monitoring vascular volume Sleep studies - 24-h ambulatory recordings of SpO2 is useful for screening for daytime sleep sequelae associated with the potential risk of this pathology in OSAS during social activities.

35. Disadvantages Decrease in PAO 2 before fall in SPO 2 Due to the shape of ODC SPO 2 94% - PAO 2 75%

36. Advantages Simple to use Non-invasive Require no warm up time Especially in African &Asian patients Cost-effectiveness over ABG

37. Control of respiration There are four main centers in the brain to regulate the respiration: 1. Inspiratory center 2. Expiratory center 3. Pneumotaxic center 4. Apneustic center. The first two centers are present on the medulla oblongata whereas the last two centers on the Pons region of brain .

38. Diseases that impair gas exchange Asthma Emphysema Occupational Respiratory Disorders Tuberculosis atelectasis . Adult respiratory distress syndrome (ARDS Bronchitis Cystic fibrosis Lung cancer

39. Nervous System disorders Sudden infant death syndrome (SIDS) Paralysis of the respiratory muscles Diseases of the Upper Respiratory Tract Strep throat Diphtheria Diseases of the Lower Respiratory Tract Laryngitis, Whooping cough ( pertussis ) pneumonia,influenza

40. Intercostal chest drainage is a flexible plastic tube that is inserted through the chest wall and into the pleural space or mediastinum It is used to remove air or fluid (pleural effusion, blood, chyle ), or pus ( empyema ) from the intrathoracic space. It is also known as a Bülau drain

41. Indications Left-sided pneumothorax (right side of image) on CT scan of the chest with chest tube in place. Pneumothorax : accumulation of air or gas in the pleural space Pleural effusion: accumulation of fluid in the pleural space Chylothorax : a collection of lymphatic fluid in the pleural space Empyema : a pyogenic infection of the pleural space Hemothorax : accumulation of blood in the pleural space Hydrothorax: accumulation of serous fluid in the pleural space Postoperative: for example, thoracotomy , oesophagectomy , cardiac surgery

42. Technique Tube thoracostomy The free end of the tube is usually attached to an underwater seal, below the level of the chest. This allows the air or fluid to escape from the pleural space, and prevents anything returning to the chest. Alternatively, the tube can be attached to a flutter valve. This allows patients with pneumothorax to remain more mobile. British Thoracic Society recommends the tube is inserted in an area described as the "safe zone", a region bordered by: the lateral border of pectoralis major, a horizontal line inferior to the axilla , the anterior border of latissimus dorsi and a horizontal line superior to the nipple. More specifically, the tube is inserted into the 5th intercostal space slightly anterior to the mid axillary line.

43. Postoperative drainage The placement technique for postoperative drainage (e.g. cardiac surgery ) differs from the technique used for emergent situations. At the completion of open cardiac procedures, chest tubes are placed through separate stab incisions, typically near the inferior aspect of the sternotomy incision. In some instances multiple drains may be used to evacuate the mediastinal , pericardial, and pleural spaces. The drainage holes are place inside the patient, and the chest tube is passed out through the incision. Once the tube is in place, it is sutured to the skin to prevent movement. The chest tube is then connected to the drainage canister using additional tubing and connectors, and connected to a suction source, typically regulated to -20cm of water.

44. Nursing management Chest drains should not be clamped Start of shift checks Patient assessment Chest drain assessment Other considerations e.g physiotherapy referral Patient Assessment HR, SaO2, BP, RR Routine vital signs:

45. Chest tubes are painful as the parietal pleura is very sensitive. Patients require regular pain relief for comfort, and to allow them to complete physiotherapy or mobilise Pain assessment should be conducted frequently and documented Observe for signs of infection and inflammation and document findings Check dressing is clean and intact Observe sutures remain intact & secure (particularly long term drains where sutures may erode over time)

46. Never lift drain above chest level The unit and all tubing should be below patients chest level to facilitate drainage Tubing should have no kinks or obstructions that may inhibit drainage Ensure all connections between chest tubes and drainage unit are tight and secure Suction is not always required, and may lead to tissue trauma and prolongation of an air leak in some patients If suction is required orders should be written by medical staff Wall suction should be set at >80mmHg or higher Suction on the Drainage unit should be set to the prescribed level

47. Milking of chest drains is only to be done with written orders from medical staff. Milking drains creates a high negative pressure that can cause pain, tissue trauma and bleeding Volume Document hourly the amount of fluid in the drainage chamber on the Fluid Balance Chart Calculate and document total hourly output if multiple drains Calculate and document cumulative total output Notify medical staff if there is a sudden increase in amount of drainage greater than 5mls/kg in 1 hour greater than 3mls/kg consistently for 3 hours

48. Air leakage (bubbling) An air leak will be characterised by intermittent bubbling in the water seal chamber when the patient with a pneumothorax exhales or coughs. The severity of the leak will be indicated by numerical grading on the UWSD (1-small leak 5-large leak) Continuous bubbling of this chamber indicates large air leak between the drain & the patient. Check drain for disconnection, dislodgement and loose connection, and assess patient condition. Notify medical staff immediately if problem cannot be remedied. Document on Fluid Balance Chart

49. Oscillation (swing) The water in the water seal chamber will rise and fall (swing) with respirations. This will diminish as the pneumothorax resolves. Watch for unexpected cessation of swing as this may indicate the tube is blocked or kinked. Cardiac surgical patients may have some of their drains in the mediastinum in which case there will be no swing in the water seal chamber. Document on Fluid Balance Chart Patients who are ambulant post operatively will have fewer complications and shorter lengths of stay.

50. Removal of the tube Clinical status is the best indicator of a reaccumulation of air or fluid. CXR should be performed if patient condition deteriorates Monitor vital signs closely (HR, SaO2, RR and BP) on removal and then every hour for 4 hours post removal, and then as per clinical condition Document the removal of drain in progress notes and on patient care record Remove sutures 5 days post drain removal Dressing to remain insitu for 24 hours post removal unless dirty Complications post drain removal include pneumothorax , bleeding and infection of the drain site

51. Nursing management

52. Assessment Client History Subjective symptoms Dyspnea with ADLs? Childhood diseases Asthma, pneumonia, allergies, croup Adult illnesses Pneumonia, sinusitis, TB, HIV, emphysema, DM, HTN, cardiac disease Vaccine history Flu, pneumonia, BCG

53. Assessment Client History Surgeries of upper or lower respiratory tract Injuries to upper or lower respiratory tract Hospitalizations Date of last CXR, PPD, PFT Recent weight loss Night sweats

54. Physical Assessment Auscultation Upright first Bare chest Open mouth breathing Full respiratory cycle Observe for dizziness

55. Physical Assessment Lungs and Thorax Inspection Palpation Fremitus 99 Crepitus Bubble wrap Chest expansion Movement

56. Physical Assessment Lungs and Thorax Percussion Pulmonary resonance Air, fluid, solid masses Intercostal spaces only Diagphragmatic excursion Normal 1 -2 inches Deep breath / percuss No breath / percuss Normally higher on the right (liver)

57. Physical Assessment Normal breath sounds Bronchial, bronchovesicular, vesicular Not heard peripherally Adventitious breath sounds Additional sounds superimposed on normal sounds Indicate pathology Crackles, wheezes, rhonchi, pleural friction rub

58. Physical Assessment Skin and Mucous Membranes Pallor, cyanosis, nail beds General Appearance Muscle development, general body build Muscles of neck, chest Endurance How does the client move in 10 – 20 steps? Speaking exertion

59. Nursing diagnoses Ineffective breathing pattern related to: increased rate and decreased depth of respirations associated with fear and anxiety decreased lung compliance ( distensibility ) associated with pleural effusion and accumulation of fluid in the pulmonary interstitium and alveoli diminished lung/chest wall expansion associated with weakness, decreased mobility, and pressure on the diaphragm as a result of peritoneal fluid accumulation (if present) respiratory depressant and/or stimulant effects of hypoxia, hypercapnia , and diminished cerebral blood flow;

60. ineffective airway clearance related to: increased airway resistance associated with edema of the bronchial mucosa and pressure on the airways resulting from engorgement of the pulmonary vessels stasis of secretions associated with decreased mobility and poor cough effort; impaired gas exchange related to: impaired diffusion of gases associated with accumulation of fluid in the pulmonary interstitium and alveoli decreased pulmonary tissue perfusion associated with decreased cardiac output.

61. Thank you…. thank you…