PTA Practice II (PTA 1017) Respiratory Failure PDF

9/27/2024 PTA Practice II (PTA 1017) Chapter 26 Cameron and Monroe ©Stanbridge University 2024 Respiratory Failure PowerPoint #1 1 1 ...

9/27/2024 PTA Practice II (PTA 1017) Chapter 26 Cameron and Monroe ©Stanbridge University 2024 Respiratory Failure PowerPoint #1 1 1  9/27/2024 Chapter Objectives  Review anatomy of the respiratory system  Describe normal physiological processes associated with ventilation and respiration  Describe pathophysiological processes leading to respiratory insufficiency and failure  Describe the prevalence and incidence of respiratory failure and its economic impact on society  Classify types of respiratory failure Identify common diseases and diagnoses associated with respiratory failure ©Stanbridge University 2024  2 2  9/27/2024 Chapter Objectives  Identify potential complications of respiratory failure and discuss their impact on rehabilitation and functional capacity  Be familiar with commonly used medical and rehabilitation tests and measures for individuals with respiratory failure  Understand the physiology and side effects behind common medications to treat respiratory failure  Describe and apply rehabilitation interventions for individuals with respiratory failure and demonstrate understanding of their proposed mechanisms of action ©Stanbridge University 2024 3 3  9/27/2024 Process of Breathing Breathing is a multistep physiological process with the purpose of delivering oxygen to and removing carbon dioxide from the human body Respiration is the process of acquiring O2 and eliminating CO2 and occurs through diffusion between the alveoli and the blood Ventilation is the movement of air in and out of the lungs The processes depend on multi-system involvement  The body relies on the cardiovascular system's ability to transport O2 and CO2 and on the tissue's ability to extract and utilize O2 while producing and eliminating CO2. ©Stanbridge University 2024  Together, the respiratory and cardiovascular systems and the tissues’ ability to extract and utilize O2 make up the O2 transport system 4 4  9/27/2024 Anatomy: Skeletal Components ©Stanbridge University 2024 FIG. 26-2 The skeletal components of the respiratory system. (Cameron/Monroe, 2011) The thoracic vertebrae, the sternum, and the ribs, which together make up the thorax 5 ©Stanbridge University 2024 5  9/27/2024 Anatomy: Rib Purpose Serves to protect heart, lungs and major vessels Dynamic lever system for ventilation Helps to keep the lungs from collapsing due to the plural ©Stanbridge University 2024 cavity Provides stable base for attachment of muscles 6 slideplayer.com 6  9/27/2024 Rib Movement During inhalation, the thorax expands in three directions:  Anterior-posterior (pump handle movement)  Vertical  Transverse (bucket handle movement) Inspiration- ribs elevate, increasing the volume of the rib cage and allowing the lungs to expand. Expiration- ribs lower down, decreasing the volume. From a side view (anteroposterior diameter, sagittal axis), the elevation and depression of ribs appear as pump handle is moving, especially in ribs 1-5. ©Stanbridge University 2024 Bucket handle movement of the ribs is a transverse (frontal axis) increase in diameter of the chest due to movement of ribs during respiration, ribs 7-10. 7 7  9/27/2024 Anatomy: Muscular Components of Breathing The following muscles together affect the volume of air in the lungs and the flow of air through the airways. Inspiration Exhalation Diaphragm- primary muscle Quiet breathing: exhalation External intercostals- principle muscle results from passive recoil of the of inspiration lungs and rib cage Sternocleidomastoid (SCM)- primary Forceful breathing: muscles can accessory muscle compress abdominal content and push up on the diaphragm ©Stanbridge University 2024 Scalenes- primary accessory muscle for active exhale Pectoralis major (sternocostal portion) Transverse abdominus Pectoralis minor Rectus abdominus Serratus anterior Internal and external obliques Internal intercostals 8 8  9/27/2024 Inspiration Contraction of the respiratory muscles causes the diaphragm to flatten and descend which decreases intrapulmonic pressure, drawing air in  Air is literally “sucked in”  Diaphragm pulls as much as 12mm down- during quiet respiration  Ribs elevate To achieve maximum lung expansion the accessory muscles of ventilation must expand the upper chest During exercise or disease:  External intercostals and scalenes assist with inspiration ©Stanbridge University 2024 9 9  9/27/2024 Expiration Passive relaxation of the diaphragm and the recoil of the lungs occurs  Increases the intrapulmonic pressure  Forces air out of lungs During assisted expiration or vigorous exercise  Internal intercostals and abdominal muscles force the air out quicker ©Stanbridge University 2024 10 10  9/27/2024 ©Stanbridge University 2024 FIG. 26-3 The muscular components of the respiratory system, (Cameron/Monroe, 2011) 11 ©Stanbridge University 2024 11  9/27/2024 Diaphragm: Primary Muscle of Respiration ©Stanbridge University 2024 FIG. 26-4 A, The diaphragm descends with muscle contraction 12 (inspiration). B, The diaphragm rises with muscle relaxation (expiration). 12  9/27/2024 The Diaphragm Innervated by phrenic nerve (composed of nerve roots C3, C4, C5) C3, C4, C5, keeps the phrenic nerve alive! Only muscle that works in 3 dimensions, and has a bony origin but not a bony insertion- the fibers converge to insert on and form the central tendon Composed primarily of slow-twitch oxidative muscle fibers (type 1) that are resistant to fatigue ©Stanbridge University 2024 At rest, the diaphragm is elevated in a domed-shaped position that optimizes the length-tension relationship of the fibers and thus the efficiency of its contraction 13 13  9/27/2024 Review of Pulmonary Anatomy Upper Respiratory Tract:  Gas conduit  Humidify cool or warm inspired air  Filter foreign matter before reaching alveoli  Sections include:  Nasal cavity  Pharynx  Larynx Lower Respiratory Tract:  Larynx  Trachea ©Stanbridge University 2024  Lungs  Bronchial tree  Alveoli Marieb, 2019 14 14  9/27/2024 Lung Compliance Compliance refers to the change in lung volume per unit of pressure change Ease with which the lung can be inflated The higher the lung compliance, the easier it is to expand the lungs Emphysema- too much compliance- air trapping Lung compliance is determined largely by two factors: ©Stanbridge University 2024 Distensibility of the lung tissue Alveolar surface tension 15 15  9/27/2024 Lung Compliance Lung tissue is very stretchy and elastic which is called lung distensibility Elasticity refers to the ability of the lungs and chest wall to recoil or deflate passively during exhalation In healthy lungs, distensibility is generally high and surfactant keeps alveolar surface tension low Assists with efficient ventilation ©Stanbridge University 2024 16 16  9/27/2024 Lung Compliance Surfactant- substance produced by alveolar cells that reduces surface tension of alveolar fluid in airways so less energy is needed to overcome the forces to expand the lungs and discourage alveolar collapse. Reduces the polarity of water molecules Production stimulated by stretch of lung tissue (ex: sigh, yawn ©Stanbridge University 2024 or deep breath) Premature babies have reduced surfactant 17 17  9/27/2024 The Bronchi and Subdivisions The air passageways in the lungs branch and branch again, about 23 times overall, in a pattern often called the bronchial tree. At the tips of the bronchial tree, conducting zone structures give way to respiratory zone structures. ©Stanbridge University 2024 Marieb, 2019 The air pathway inferior to the larynx consists of the trachea and the main, lobar, and segmental bronchi, which branch into the smaller bronchi and bronchioles until reaching the terminal bronchioles of the 18 18 lungs. 18  9/27/2024 ©Stanbridge University 2024 ©Stanbridge University 2024 19 19  9/27/2024 Respiratory Zone Structures ©Stanbridge University 2024 Marieb, 2019 20 20  9/27/2024 Alveoli-Capillary Units The alveolar membrane is made up of a single layer of endothelial cells, creating a very thin membrane through which gas exchange can occur Alveoli-capillary units: Oxygen diffuses across the alveolar–capillary septum into the red blood cells in the lung capillaries Then it combines with hemoglobin to be transported back to the heart ©Stanbridge University 2024 Carbon dioxide diffuses in the opposite direction 21 21  9/27/2024 Respiration- Gas Exchange ©Stanbridge University 2024 Image from study.com 22 22  9/27/2024 Control of Breathing Spontaneous breathing is largely involuntary Integrated activity of central respiratory center in the brainstem (pons and medulla) and peripheral receptors in lungs, airways, chest wall, and blood vessels Respiratory center in the brainstem integrates information from central and peripheral chemoreceptors and mechanoreceptors in the chest wall to stimulate motor neurons that innervate the respiratory muscles Breathing can also be voluntarily controlled via the motor cortex  This type of control is used to perform volitional activities such as:  Singing ©Stanbridge University 2024  Holding your breath to go under water  Blowing bubbles  Blowing out a candle  Playing a wind instrument  During exercise 23 23  9/27/2024 Respiratory Physiology  Mechanoreceptors in the lungs and the peripheral skeletal muscles respond to stretch or movement to regulate the overall breathing pattern  As the lungs near full inspiratory volume, mechanoreceptors inhibit inhalation and facilitate exhalation so that the lungs do not become overstretched ©Stanbridge University 2024 24 24  9/27/2024 Respiratory Physiology  Hypercapnic drive for breathing (primary):  Respiratory drive determined by:  Central chemoreceptors sense levels of carbon dioxide  Peripheral chemoreceptors sense levels of oxygen  Central chemoreceptors in brainstem respond to blood levels of CO2 to provide the primary drive for breathing ©Stanbridge University 2024  As CO2 levels rise, they stimulate increased ventilation to blow off the extra CO2 25 25  9/27/2024 Respiratory Physiology  Hypoxic drive for breathing (secondary):  The peripheral chemoreceptors in the aortic arch and the common carotid arteries respond to blood O2 levels  If O2 levels fall below normal, these receptors stimulate increased ventilation  This serves as a back-up for the hypercapnic drive ©Stanbridge University 2024 26 26  9/27/2024 Respiratory Physiology ◦ Alveolar-Arterial oxygen difference: difference in O2 concentration between the arterial blood and the air within the alveoli ◦ Abbreviated as PAO2–PaO2 ◦ This value reflects the adequacy of gas exchange ©Stanbridge University 2024 within the lung ◦ Note: A= Alveolar; a= arterial 27 27  9/27/2024 Respiratory Physiology ◦ Normal PAO2–PaO2 is < 20 mm Hg ◦ May be as low as 10 mmHg in children and as high as 30 mmHg in the elderly ◦ PAO2–PaO2 will widen if diffusion between the alveoli and the pulmonary circulation is ©Stanbridge University 2024 impaired 28 28  9/27/2024 Respiratory Physiology  The partial pressures of O2 and CO2 are the driving forces of gas exchange and diffusion (Fig. 26-8 next slide)  Gases will diffuse from an area with higher partial pressure to an area with lower partial pressure to move toward equilibrium ©Stanbridge University 2024 29 29  9/27/2024 Gas Exchange Occurs Through Diffusion in Alveoli ©Stanbridge University 2024 FIG. 26-8 Gas exchange occurs through diffusion in the alveoli. 30 ©Stanbridge University 2024 30  9/27/2024 Ventilation and Perfusion Matching ◦ Ventilation (V) refers to the movement of a volume of air from the atmosphere in and out of the airways ◦ Depends on the ability of the respiratory muscles to generate force to bring air into the lungs ◦ Perfusion (Q) of the lungs refers to the amount of blood flowing through the lungs ©Stanbridge University 2024 31 31  9/27/2024 Ventilation and Perfusion Matching ◦ Ventilation and perfusion must match for adequate gas exchange and respiration to occur ◦ Normally the V:Q ratio ranges from 0.6 to 3.0 ◦ The higher value represents the upper portion of the lungs where there is more ventilation (V) and less perfusion (Q) ◦ The lesser value represents the lower portion where there is more perfusion (Q) and less ventilation (V) ©Stanbridge University 2024 32 32  9/27/2024 Ventilation and Perfusion Matching ◦ Optimal gas exchange occurs where V and Q are equal and the V:Q ratio= 1 ◦ V:Q mismatch reduces gas exchange and limits respiratory function ◦ May occur if either V or Q are impaired ©Stanbridge University 2024 33 33  9/27/2024 Dead Space  Refers to areas in the lungs in which the air is not participating in respiration; can cause breathing to be impaired  Can be anatomical (normal) or can be pathological (abnormal)  Anatomical dead spaces typically have a higher V:Q ratio due to the upper airways (conducting) not participating in gas exchange ©Stanbridge University 2024  Pathological dead space describes areas that should be participating in gas exchange (respiration) but are not  i.e. dead space may occur when a PE occludes perfusion to given area of the lungs, limiting alveolar perfusion 34 34  9/27/2024 Summary of the Steps in O2 & CO2 Transport  Step 1: Ventilation – O2 inhaled, air passes down the conducting airways to the respiratory airways  Step 2: Lung Diffusion – (Alveolar-to-Arterial PO2 Difference)- alveolar gas exchange by diffusion with capillary (alveoli-capillary unit- see next slide)  Step 3: Transport - Gas Transport by the blood to body ©Stanbridge University 2024  Step 4: Tissue Diffusion - Exchange of Gases Between Capillary and Tissue Mitochondria  For the O2 transport system to function effectively and efficiently, each component in Fig. 26-1 The Oxygen transport system mobilizes oxygen into the body and eliminates carbon dioxide. from McArdle WD, Katch FI, Fig 26-1 must work optimally Katch VL: Exercise physiology: Energy, nutrition, and human performance, ed 5, Philadelphia, 2001, Lippincott Williams & Wilkins. 35 35  9/27/2024 Learning Assessment 1) Which two muscles are the primary accessory muscles of inspiration? a) Transverse abdominus and internal intercostals b) Rectus abdominus and diaphragm c) Sternocleidomastoid and scalenes d) Scalenes and external obliques ©Stanbridge University 2024 36 36  9/27/2024 Learning Assessment 2) With inspiration, the diaphragm does which of the following? a) Descends as air is being pulled into lungs b) Descends as air is being sucked out of lungs c) Ascends as air is being pulled into lungs d) Ascends as air is being sucked out of lungs ©Stanbridge University 2024 37 37  9/27/2024 Pathology- O2 Transport Small deficiencies in one component of the O2 transport system may be compensated for by other systems When deficiencies increase or are prolonged or demands increase, compensation generally fails and results in respiratory failure. Since activity increases demands on the O2 transport system, the rehabilitation professional may be able to compensate for reduced O2 transport by curtailing the patient's activity level or intensity. ©Stanbridge University 2024 38 38  9/27/2024 Pathology- Skeletal Components For optimal ventilation, the lungs and the thorax must be able to expand in all dimensions: Anterior-posterior Superior-inferior Medial-lateral This requires appropriate rib mobility Limitations or restrictions in the ability of either the lungs or ribs ©Stanbridge University 2024 to expand will increase the workload (O2 demand) of the respiratory system and limit the airflow May lead to respiratory muscle fatigue and/or respiratory failure Often seen in barrel chest deformity with COPD 39 39  9/27/2024 Work of Breathing (WOB) Work of breathing (WOB) is the amount of energy or O2 consumption needed by the respiratory muscles to produce enough ventilation and respiration to meet the metabolic demands of the body Under normal, resting conditions- the WOB is about 5% of the max O2 uptake (VO2max) In individuals with pulmonary problems, WOB may exceed 50% of the VO2max; results in: Reduced energy reserve ©Stanbridge University 2024 Decreased exercise capacity Stresses other bodily systems ©Stanbridge University 2024 40 40  9/27/2024 Respiratory Pathophysiology Certain diseases and/or the presence of mucus may increase airway thickness or limit the number of alveoli participating in respiration Infiltrates from pneumonia may reduce the number of alveoli available for ventilation Emphysema will reduce alveolar surface area by destroying the alveolar walls ©Stanbridge University 2024 41 41  9/27/2024 Pathology- Respiratory Failure  Respiratory failure is caused by impairment of gas exchange between ambient air and circulating blood because of reduced intrapulmonary gas exchange or reduced movement of gases in and out of the lungs  Efficient maintenance of appropriate blood gases is vital to survival and provides the energy needed for daily activities ©Stanbridge University 2024  Can be caused by disorders of the airways, lungs, or the skeletal, muscular and neural components of the respiratory system 42 42  9/27/2024 Pathophysiology of Respiratory Failure  Hypoventilation refers to a state of decreased or inadequate ventilation  Primary causes are central nervous system depression, neurological disease, or disorders of the respiratory muscles  Ventilation-perfusion mismatch results in impaired gas exchange in the affected areas of lungs and a decreased ability to maintain a steady state of O2 and CO2 ©Stanbridge University 2024 concentrations  Diffusion abnormalities increases the overall WOB by interfering with gas exchange 43 43  9/27/2024 Pathology- Acute Respiratory Distress Syndrome (ARDS) Some of the causes of ARDS include shock, severe trauma or infection, overwhelming pneumonia, and inhaled toxins Increased vascular permeability resembling that of the inflammatory response is a common feature  Fluid seeps into the interstitial spaces and overwhelms the alveoli, leading to pulmonary edema Lung compliance and gas exchange are severely compromised. ©Stanbridge University 2024 44 44  9/27/2024 Pathophysiology of Respiratory Failure Respiratory failure canbe classified as primarily hypoxic (known as type I) or as primarily hypercapnic (known as type II)  Hypoxic respiratory failure is primarily characterized by abnormally low Pao2 and a normal or close to normal Paco2  Hypercapnic respiratory failure is primarily characterized by an abnormally elevated Paco2 that may or may not be ©Stanbridge University 2024 associated with hypoxia 45 45  9/27/2024 Pathology- Respiratory Failure  In adults usually due to ARDS or COPD (COPD 4th leading cause of death in the US)  Respiratory system cannot meet the demands; inadequate delivery of O2 or inadequate elimination of CO2  When the pulmonary system cannot maintain a steady state of gas exchange it results in respiratory insufficiency and subsequent failure ©Stanbridge University 2024 46 46  9/27/2024 Pathology- Dead Space and V/Q Ratio Can be due to a disease process or abnormal condition that limits perfusion but not ventilation  Example: pulmonary embolism occludes blood flow limiting alveolar perfusion; V>Q (V/Q>1) Can be due to disease process or abnormal condition that limits ventilation but not ©Stanbridge University 2024 perfusion  Pulmonary shunt where perfusion is greater than ventilation;  Example: atelectasis (collapse of airways) or consolidation (filling of alveoli with secretions) V