{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

ventilation - Anatomic Components Anatomic of Respiratory...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Anatomic Components Anatomic of Respiratory System: • Upper Airways Nasal cavity and pharynx • Lower Airways Larynx, trachea, bronchial tree • Lung Lobes 2 on left, 3 on right • Tracheobronchial tree • Alveolar unit Pharynx: NASOPHARYNX OROPHAYNX LARYNGOPHARYNX Nose primary functions: Nose Filter Humidify Warm inspired gas From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 VOCAL CORDS VOCAL CORDS Lined by mucous membrane that forms two folds that protrude inward. Lined by mucous membrane that forms two folds that protrude inward. LARYNX Upper folds are called false vocal cords. Upper folds are called false vocal cords. Framework of nine cartilages held in position by intrinsic and extrinsic muscles. Lower pair are the true vocal cords. Lower pair are the true vocal cords. SINGLE: Thyroid Cricoid Epiglottis Medial border is composed of a strong band of elastic tissue called the vocal Medial border is composed of a strong band of elastic tissue called the vocal ligament.AIRED: P Arytenoid Corniculate Cuneiform ligament. Space in between the true vocal cords is called the rima glottidis or glottis. Space in between the true vocal cords is called the rima glottidis or glottis. From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 NOTE: The precise number of generations between the NOTE: The precise number of generations between the subsegmental bronchi and the alveolar sacs is not known. subsegmental bronchi and the alveolar sacs is not known. Schematic drawing of the anatomic structures distal to the terminal Schematic drawing of the anatomic structures distal to the terminal bronchioles; collectively, these are referred to as the primary lobule. bronchioles; collectively, these are referred to as the primary lobule. Alveolar unit Alveolar Functional Zones of Respiratory System Functional 1. Conducting Zone • Upper and lower airways – Filter, warm and humidify, and conduct gases • Ventilation = movement of gases, O2 and CO2, in and out of the lungs • Conducting zone = anatomical deadspace (1/3) Back to Index Functional Zones of Respiratory System Functional 2. Respiratory Zone • Bronchioles, alveolar ducts, and alveoli • Alveoli = primary site for gas exchange • Respiration = exchange of gases between the lungs and blood From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 Quick Review Quick Although the respiratory system can be viewed as 3 main components, a functional description is more useful because it distinguishes the process of ventilation from that of respiration. The two functional areas are the conducting and respiratory zones. The conducting zone participates in ventilation. Inspired gas is filtered, warmed, and humidified as it is enters the lungs. Gas movement in the conducting zone is termed dead space ventilation. Increased levels of dead space can cause the patient to increase their rate and depth of breathing to compensate for the effect on ventilation and respiration. Quick Review Quick The exchange of gases between the alveoli and blood The is called respiration and occurs in the respiratory zone. This area is comprised of small airways, alveoli, and the pulmonary capillaries. Gas enters the respiratory zone from the conducting airways and blood circulates the alveoli from the pulmonary capillaries. In order to have affective respiration there must be adequate levels of ventilation and pulmonary blood flow. Pulmonary Mechanics Pulmonary Respiratory Mechanics Pulmonary Mechanics Pulmonary • Requires chest wall (thorax) and respiratory muscles • Pleura (lining) - lubricant • Opposing forces keep lungs inflated (thorax=out, lungs=in) • Muscles provide force(work) • Diaphragm = major muscle of ventilation Back to Index Inspiration (ACTIVE) Inspiration Diaphragm contracts - moves downward Thoracic volume increases Lung (pleural) pressure decreases - air moves in Back to Index Expiration (PASSIVE) Expiration Diaphragm relaxes - moves up Thoracic volume decreases Lung (pleural) pressure decreases air moves out EXPIRATION Back to Index END-EXPIRATION EXPIRATION END-EXPIRATION From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 Pulmonary Mechanics Pulmonary Compliance • Amount of work required to inflate lungs – “how stiff is the lung?” • Compliance = ΔVolume (L/cmH20) ΔPressure • • • Normal = 0. 1L/cmH20 (100 ml/cmH20) 2 2 High compliance easier - to inflate Low compliance - harder to inflate Back to Index From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 Lung Compliance Changes Lung and the P-V Loop Volume Targeted Ventilation Preset VT COMPLIANCE COMPLIANCE Increased Normal Decreased Volume (mL) Paw (cm H2O) PIP levels From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Overdistension Overdistension With little or no change in VT With little or no change in VT Volume (ml) Normal Abnormal Pressure (cm H2O) Paw rises Paw rises From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Pulmonary Mechanics Pulmonary Elastance • Amount of work required to exhale • Elastance = ΔPressure (cmH 0/L) ΔVolume • • • 2 Reciprocal of compliance Good compliance = bad elastance Bad compliance = good elastance Back to Index Pulmonary Mechanics Pulmonary Resistance • Amount of work required to move air through the lungs • Resistance = Pressure (cmH20/L/sec) 2 Flow • Primarily influenced by airway diameter • Normal = 0.6 - 2.4 cmH20/L/sec 2 Back to Index Quick Review Quick Ventilation occurs due to a pressure gradient Ventilation between the lungs and mouth. Contraction of the respiratory muscles results in a pressure - volume change in the lungs. As pressure decreases air moves into the lungs during inspiration, and as lung pressure increases gas moves out of the lungs during expiration. The compliance of the pulmonary system influences the amount of pressure required to affect a volume change. Airway resistance also influences the effort needed to create a volume change. Lung Volumes and Capacities Pulmonary Function Lung Volumes and Capacities Lung Volumes Capacities Tidal Volume (VT) T Inspiratory Reserve Volume (IRV) Expiratory Reserve Volume (ERV) Residual Volume (RV) Inspiratory Capacity (IC) Vital Capacity (VC) Functional Residual Capacity (FRC) Total Lung Capacity (TLC) Back to Index FIGURE 4-1. Normal lung volumes and capacities. IRV = inspiratory reserve volume; VT = tidal volume; RV = residual volume; ERV = expiratory reserve volume; TLC = total lung capacity; VC = vital capacity; IC = inspiratory capacity; FRC = functional residual capcity. Assessment of Ventilation Assessment Signs & Symptoms Assessment of Ventilation Assessment Qualitative • • • • • • Respiratory pattern Accessory muscle use Prolonged expiration Shortness of Breath (SOB) Cyanosis Minute ventilation (VE=f x VT) T Back to Index Assessment of Ventilation • Quantitative • • • • • ABG’s (primarily CO2) 2 Pulse oximetry Capnography Transcutaneous monitoring NICO Control of Respiration Control 1. Chemical Stimulants • Oxygen and carbon dioxide influence rate and depth of respiration • CO2 is the primary stimulus 2 ↑ CO2 = ↑ rate and/or depth 2 ↓ CO2 = ↓ rate and/or depth 2 ↓ O2 = ↑ ventilation 2 ↑ O2 = ↓ ventilation 2 Back to Index Quick Review Quick Respiration is the exchange of gases between Respiration the lungs and pulmonary blood vessels (external respiration) and between the blood and tissues (internal respiration). Oxygen and carbon dioxide move from one area to the other due to pressure gradients. Systemic levels of CO2 and O2, influence 2 2 the depth and rate of ventilation with carbon dioxide acting as the primary stimulus for ventilation. Assessment of Respiration Assessment Arterial Blood Gas Variables • pH • PaCO2 2 Back to Index This indicates the relative acidity or alkalinity of the blood. The normal range is 7.35 - 7.45. Values less than 7.35 are acid, and those above 7.45 alkaline. The partial pressure (tension) of carbon dioxide in the arterial blood. The normal range is 35 - 45 torr. Values less than 35 indicate excessive levels of ventilation, and values above 45 indicate a drop in ventilation. Assessment of Respiration Assessment Arterial Blood Gas Variables • PaO2 2 • SaO2 2 Back to Index The partial pressure (tension) of oxygen in the arterial blood. The normal range, breathing room air, is 80 - 100 torr, values less than 70 indicate a lack of oxygen. This indicates the percentage of red blood cells that are combined with O2. 2 The normal range, breathing room air, is 90 - 100%. Levels below 90% indicate a lack of oxygen. FYI FYI Gas pressures, or tensions, are usually expressed in units of torr. One torr is equal to one mm Hg (millimeter of mercury pressure), similar to what your local weatherman uses. Torr is used to honor Evangelista Torricelli who invented the mercury barometer. Torr and mm Hg can be used interchangeably, however torr is the preferred unit. Ventilation-Perfusion Relationships Ventilation-Perfusion • • • • • • • Perfusion(Q) Ventilation(V) Need V/Q matching to achieve effective gas exchange. Normal V/Q ratio = 0.8 Increased V/Q ventilation>perfusion (deadspace) Decreased V/Q perfusion>ventilation (shunt) Abnormal V/Q ratios alter work of breathing Back to Index From Cardiopulmonary Anatomy and Physiology. Terry Des Jardins. 3rd Ed. Delmar. Albany,NY.1998 Balance Between External Respiration and Balance Internal Respiration (supply and demand) • Exercise increases O2 consumption and CO2 2 2 production. • If body cannot maintain balance to hypoxia and hypercarbia is reflected by clinical and laboratory assessment. • Need adequate respiratory and cardiac function in order to maintain acid-base and supplydemand balance. Quick Review Quick ABG’s are used to assess the effectiveness of respiration. ABG’s Problems in external respiration occur from V/Q mismatches. Low V/Q areas produce oxygenation problems (shunting) and high V/Q ratios represent alveolar dead space ventilation. Internal respiration is the exchange of O2 and CO2 between the arterial blood 2 2 and the tissues. Metabolic activity of the cells requires O2 2 and produces CO2 as a byproduct. ABGs are used to 2 assess the level of O2 available for metabolism and the 2 effectiveness of lungs in removing CO2. 2 Indications for Mechanical Ventilation • Simply stated mechanical ventilation is indicated when a patient is unable to adequately remove CO2 and 2 maintain adequate levels of O2 in the 2 arterial blood. • Ventilation may be short or long-term depending on underlying disorder. Goals of Mechanical Ventilation • • • Decrease work of breathing Increase alveolar ventilation Maintain ABG values within normal range • Improve distribution of inspired gases Back to Index Obstructive Lung Disease Goal of Ventilation: Reduce work of breathing 1.Emphysema 1.Emphysema • Pathology: Destruction of terminal airways and air sacs. • Concerns: Must assure adequate time and pressure for exhalation. Low pressures desirable to reduce the likelihood of damage to the lung, additional high airway resistance; end stages will also have poor lung compliance. Obstructive Lung Disease Obstructive Goal of Ventilation : Reduce work of breathing 2. Bronchitis • Pathology: Chronic inflammation of mucousproducing cells. Hyper-reactive airways. Excessive abnormal secretions from irritation (infection, allergies, smoke, etc.). • Concerns: Ventilation only supportive; must reduce volume of secretions and remove irritants. Respiratory Dysfunction Diagnosis confirmed via PFTs Obstructive Lung Disease Obstructive • Decreased expiratory flowrates • Increased RV, FRC, and TLC = air trapping “can’t get air out” • Exhibit increased airway resistance Decreased elastance; increased compliance • Examples: (COPD) a. asthma b. emphysema c. bronchitis d. bronchiolitis Respiratory Dysfunction Respiratory Restrictive Lung Disease • Decreased volumes and capacities, normal flowrates • “can’t get volume in” • Exhibit decreased compliance, increased elastance • Examples: a. pulmonary fibrosis b. pulmonary edema c. pneumo/hemo thorax d. ARDS/IRDS e. chest wall deformities f. obesity g. neuromuscular disorders Work of Breathing Work Work = Force (pressure) x Distance (volume) • Pressure generated must overcome: a. resistance of airways b. compliance of lung and chest wall • Muscles of respiration are very inefficient – can fatigue and lead to respiratory failure • Signs of fatigue: a. increased respiratory rate b. increased arterial CO2 2 c. paradoxical breathing Mechanical Ventilation Mechanical 1. Negative Pressure Ventilators • • Iron lung Cuirass 2. Positive Pressure Ventilators • Volume ventilators • Pressure ventilators Negative Pressure Ventilation • Creates a negative (subatmospheric) extrathoracic pressure to provide a pressure gradient. • Mouth (atmospheric), Lungs (subatmospheric) = Inspiration • Problems? Back to Index Emerson Iron Lung NEV 100 + Neumo suit Positive Pressure Ventilation • Creates a positive intrapleural pressure in presence of atmospheric extrathoracic pressure. • Mouth (atmospheric), Lungs (atmospheric) = Instpiration • Problems? Negative vs. Positive Pressure Ventilation Negative Positive Pressure Ventilation Positive Volume-Targeted Ventilation • • • • Preset volume is delivered to patient. Inspiration ends once volume is delivered. Volume constant, pressure variable. Ensures proper amount of air is delivered to lungs regardless of lung condition • May generate undesirable(high) airway pressures. Positive Pressure Ventilation Positive Pressure-Targeted Ventilation • Preset inspiratory pressure is delivered to patient. • Pressure constant, volume variable. • Clinician determines ventilating pressures. • Volumes may increase or decrease in response to changing lung conditions. (TRIGGERING) Starting Inspiration 1. Manual Trigger 1. 2. Patient (Flow/Pressure)Trigger -(assist) 3. Time-Trigger- (control) 4. Patient/Time-Trigger (assist/control) (CYCLING) Ending Expiration (CYCLING) 1. Pressure 2. Volume 3. Time 4. Flow 5. Manual Ventilator Parameters Ventilator Settings Volume-Targeted Ventilation Volume-Targeted Tidal Volume • Definition: How much air movement is needed to adequately remove CO2 from the 2 blood. • Setting: Usually 8-10mL/kg or adjusted as indicated by arterial CO2 levels. 2 Respiratory Rate Respiratory • Definition: The frequency that the tidal volume must be delivered to adequately remove CO2. 2 • Setting: Usually 12-14/min may be increased or decreased as indicated by arterial CO2 levels. 2 Peak Inspiratory Pressure Peak • Definition: Reflects airway resistance and lung compliance (work required to move air through the airways and into the alveoli). Elevated with either increased resistance (tracheal tube, ventilator circuitry) or decreased compliance. Inspiratory Time Inspiratory • Definition: Part of the ventilatory cycle necessary for inspiration • Setting: Maintain an I:E of 1:2 or greater (1:3, 1:4, etc.) Pressure-Targeted Ventilation Pressure-Targeted Peak Inspiratory Pressure • Definition: Reflects airway resistance and/or lung compliance. • Setting: Set to allow the delivery of an adequate tidal volume. Back to Index Modes of Ventilation Modes Control Control • Indicated when patient cannot initiate inspiration. • Inspiration is initiated by timing device. • Machine controlled breath. Control Mode (Pressure-Targeted Ventilation) Time-Cycled Time- Flow (L/min) Set PC level Pressure (cm H2O) Ve olum (ml) Tim (sec ) Te im From CD: Essentials of Ventilator Graphics ©2000 RespiMedu. All Rights Reserved Click on the graphic to see details Click on the graphic to see details Back to Index Control Mode Control (Pressure-Targeted Ventilation) Time-Cycled Flow (L/min) Set PC level Press (cm H2O) ure Volume (ml) Time (sec) From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Assist-Control Assist-Control •Breath initiated by patient unless rate falls below selected respiratory rate. •Each breath’s pressure or volume is preset. Assisted Mode Assisted Mode (Pressure-Targeted Ventilation) (Volume-Targeted Ventilation) Patient Triggered, Pressure Limited, Time Cycled Ventilation Patient triggered, Flow limited, Volume cycled Ventilation Time-Cycled Flow (L/m) F low (L/min) Pressure Pressure (cm H2O) Set PC level (cm H2O) Ve olum (ml) From CD: Essentials of Ventilator Graphics Preset VT Volume (mL) Volume Cycling Time (sec) T e (sec im ) ©2000 RespiMedu. All Rights Reserved From CD: Essentials of Ventilator Graphics Click on the graphics to see details Click on the graphics to see details Back to Index ©2000 RespiMedu. All Rights Reserved Assist-Control Mode Assist-Control (Pressure-Targeted Ventilation) Patient Triggered, Pressure Limited, Time Cycled Ventilation Time-Cycled Flow (L/min) Press (cm H2O) ure Set PC level Volume (ml) Time (sec From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Assist-Control Mode Assist-Control (Volume-Targeted Ventilation) Patient triggered, Flow limited, Volume cycled Ventilation Flow (L/m) Pressure (cm H2O) Preset VT Volume (mL) Volume Cycling Time (sec) From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Flow-Trak™ VCV made easy! What Is Flow-Trak What • It’s an enhancement to standard VCV • Doesn’t punish the patient if Peak Flow setting is inappropriately low • If the peak flow or tidal volume does not meet the patient’s demand, Flow-Trak will give additional flow to satisfy patient need Flow-Trak Flow-Trak Features It’s always on No additional settings Allows unrestricted access to flow/volume within a VCV breath without increasing driving pressure Maintains the same expiratory time Benefits Easy to use Enhances patient-toventilator synchrony Reduces the likelihood of breath-stacking and Auto-PEEP Flow-Trak Flow-Trak Features High Ve alarm Switches back to VCV if initial flow demand decreases before set Vt is delivered Patient controls insp time on Flow-Trak breaths Benefits Alerts clinician to consistent increased ventilatory demands Ensures the preset Vt is always delivered Patient-to ventilator synchrony Flow-Trak – Simple Version Flow-Trak • Inspiration – Starts off as standard VCV breath either with square or decelerating flow pattern – If circuit pressure drops to PEEP minus 2cm H20 (patient outdraws set flow), Flow-Trak is initiated. • Once Flow-Trak is triggered it will pressure control to a target of 2 cmH2O above baseline. Without FlowTrak Without Concave Pressure Curve Pressure cmH2O Profound Patient-to-ventilator dysynchrony ensues Without FlowTrak Without Breath Triggered Pressure cmH2O Flow LPM Flow-Trak 60 VCV Breath Flow-Trak Breath Flow LPM 20 Pressure decrease Pressure cmH2O 5 Time Intermittent Mandatory Ventilation (IMV) Intermittent • Machine delivers a set number of machine breaths, patient can breathe spontaneously between machine breaths. Synchronized Intermittent Mandatory Ventilation (IMV) •Patient-initiated breath. •Prevents breath stacking. Back to Index SIMV+PS SIMV+PS (Volume-Targeted Ventilation) PS Breath Flow (L/min) Pressure Flow-cycled Set PS level (cm H2O) Volume (ml) From CD “Esssentials of Ventilator Graphics”. ©2000 RespiMedu. With permission Continuous Positive Airway Pressure Continuous (CPAP) • Preset pressure is maintained in the airway. • Patient must breathe spontaneously - no mechanical breaths delivered. • “breathing at an elevated baseline” • Increases lung volumes, improves oxygenation. CPAP F low (L/min) Pressu re (cm H2O) CPAP level Ve olum (ml) From CD: Essentials of Ventilator Graphics Time (sec) ©2000 RespiMedu. All Rights Reserved Click on the graphic to see details Click on the graphic to see details Back to Index CPAP CPAP Flo...
View Full Document

{[ snackBarMessage ]}