Respiratory Assessment
► General assessment
► Respiratory function (VITAL)
► Lung capacities (pulmonary function test)
► Principles of gas exchange
► Principles of oxygen transport
► Ventilation / Perfusion ratios
READ ON THESE TOPICS IN CH 21
► Lung volumes & lung capacities
► Pulmonary function
► Breath sounds
► Gas exchange and oxygen transport
► Ventilation-perfusion ratios
► Oxyhemoglobin dissociation curve
Assessment Review
Four Factors in Respiratory Function
► Neurochemical control of ventilation
► Mechanics of breathing
► Gas Transport (diffusion)
► Control of pulmonary circulation
Neurochemical Control of Ventilation
► Respiratory center in the brainstem.
- Dorsal respiratory group (DRG) – control rhythm of breathing
- Ventral respiratory group (VRG) – comes into play with excitement (exercise.etc.)
- Both on a feedback group of the lungs called afferant nervous system
Lung Receptors
- Irritant receptors - detect noctious stimuli, broncho irritant
- Stretch receptors – keeps you from over stretching the lungs
- J-receptors – juxtapulmonary capillary - associated with the alveoli of the lungs and the cough
receptors. Associated
Chemoreceptors - regulators
► Monitor pH, PaCO2, and PaO2.
► Central chemoreceptors*
- monitor changes in arterial blood and CSF.
- CO2 readily crosses the BBB.
- may be “reset” by long term conditions.
-results in poor response to PaCO2 changes.
*Constantly detecting changes in CSF
Mechanics of Breathing
► Major and accessory muscles(key components)
- diaphragm
- external intercostal muscles
Aveolar Surface Tension (inner lung)
- Surfactant
- Structure and protects against fluid influx.
► Elastic Recoil
- tendency of the lungs to return to rest.
- compromised by high ventilation volumes
- diseases create resistance to expansion
► Compliance
- measure of distensibility
- determined by aveolar surface tension and elastic recoil
Alterations: Aging, emphysema, ARDS, pneumonia, pulmonary edema
► Work of Breathing**
- muscular effort required for ventilation.
- requires oxygen and energy
- normally very low
- various alterations.
- increases oxygen demand
Hypoxic will cause work of breathing to increase
Gas Transport / Pulmonary Circulation
► Distribution of ventilation and perfusion
► Oxygen transport
► Carbon dioxide transport
Important capacities
► Tidal volume – normal volume with each breath (5-10mL/kg)
► Minute ventilation – Combination of RR and tidal volume over one minute (4-8 L/min)
► Vital Capacity – maximum amount of air expired following maximum inhalation
► Inspiratory Force – effort during inspiration.
► Function Residual Capacity
General Inspection
► Position.
 Position of comfort?
► Effort to breathe.
► Accessory muscle use.
► Unequal chest wall movement.
► Nasal flaring.
*pursing lips helps to keep the lungs open naurally
Examination of Chest Wall
► Size & shape.
 AP diameter.
► Bilateral symmetry.
► Excursion.
► Abnormal retraction or bulging.
► Paradoxical movement.
 E.g.. Flail Chest.
► Respiratory Paradox:
 Abdomen pulled in with every breath.
Skin & Mucous Membranes
► Central Cyanosis.
 Peripheral Cyanosis.
 Never assume that O2 levels are okay just because color is okay – varies with Hgb & CO.
Clubbing
► Chronic Hypoxic Conditions:
Musculoskeletal Development
Kyphosis
Barrel Chest
Pectus Carinatum
Pectus Excavatum
Kyphosis
► Elevation of scapular & outward curvature of spine. Hunchback. (airtrapping in the back)
Barrel Chest
► Increased AP diameter of thorax. 1:2 to 5:7
*Lackiing in elastic reoil, often seen in COPD also causing air trapping. Eveerything is expanded and stiff
Pectus Excavatum (Funnel Chest)
► Depression in lower portion of sternum.
Pectus Carinatum (Pigeon Chest)
► Sternum protrudes forward.
Tracheal Position
► Normal.
► Deviation.
► Tension PTX.
► Away from affected side.
► Severe Atelectasis.
► Towards affected side.
Neck Vein Distention
► Inspect with HOB elevated.
► What do the neck veins do with respirations?
(COPD)
► Inspiration:
 Collapse.
► Expiration:
 Distend.
Respiratory Rate & Quality
► Eupnea.
 Normal. WOB.
► Bradypnea.
 Rate.
► Tachypnea (Dyspnea!).
 Rate & Depth.
► Hypoventilation.
 Depth. Irregular.
► Hyperventilation.
 Rate & Depth.
 Respiratory Patterns
► Kussmaul’s: (DKA)
 Rate, Depth. Labored. Metabolic acidosis.
► Apnea:
 Period of cessation of breathing.
► Cheyne Stokes: (seen in neurological disorders)
 Alt. periods of deep & shallow, with apnea.
► Biot or Ataxic: (seen in neurological injuries)
 No pattern. Irregular with apnea.
► Tactile Fremitus
 Vibration of chest wall with vocalization.
► Increased:
 Consolidation.
 Disorders:
 Decreased:
 air/unit volume of lung.
 Disorders:
► Subcutaneous Emphysema
 Air in subcutaneous tissue. (can go anywhere in the body)
► Causes:
 Large leak.
 Ventilator
pressure (PEEP).
 Chest tube (CT)
not patent.
 CT drainage port
located beneath
the skin & not in
Res. Auscultation Topics…
► Normal Breath Sounds.
► Adventitious Breath Sounds.
► Transmitted Voice Sounds.
Normal Breath Sounds
► Vesicular: Heard over majority of lung fields. Low, soft sound.
► Bronchovesicular: Heard over the main stem bronchus. Medium pitched.
► Tracheobronchial: Heard over the trachea only. High pitched & hollow.
Adventitious Breath Sounds
Fine Crackles:
Caused by accumulation of fluid, mucus or pus in alveoli & smaller airways.
Wheezes:
Musical, squeaky sound caused by bronchospasm.
Coarse Crackles:
Caused by narrowing of the larger airways by mucus or bronchospasm.
Pleural Friction Rub:
Caused by inflamed pleural membranes rubbing against one another.
pleural space.
Diminished Breath Sounds:
Breath sounds which are not heard well.
Stridor:
Crowing sound associated with upper airway obstruction. Often caused by intubation
 Rhonchi:
 Consolidation sounds:
 Chest hair:
 Absent breath sounds:
Transmitted Voice Sounds
► Egophony
► Bronchophony.
► Whispered Pectoriloquy.
Oxygen Transport
Review Concept Topics…
► Inspiration & Expiration
► Gas exchange
► Oxygen transport
► Alveoli
► Hypoxia
► Pulmonary Shunting
► Ventilation-Perfusion Ratios
Oxyhemoglobin Dissociation Curve
► Inspiration: Active. Diaphragm (60% – 70% Vt).
► Expiration: Passive.
Concepts of gas exchange
► Partial pressure of a gas dissolved in a liquid
► Gas is dissolved until an equalibrium is a achieved
► Based on the principle of diffusion (higher to lower concentration) – taking oxygen in diffuses into the cells
► Concepts of gas exchange
► Gas is dissolved until an equilibrium is a achieved
► Based on the principle of diffusion
► Oxygen and CO2 diffuse readily until equilibrium is achieved.
Partial Pressure Symbols
► PO2 – Partial pressure of oxygen
► PAO2 – partial pressure of aveolar oxygen
► PaO2 – partial pressure of arterial oxygen***
► PACO2 – partial pressure of aveolar carbon dioxide
► PaCO2 – partial pressure of arterial carbon dioxide
Pulmonary Circulation
► Entire CO reaches the pulmonary circulation.
► Low pressure system. (because of fluctuation in fluids that goes to the lungs)
► Pulmonary artery enters at hilus (sm opening in medial part of lungs).
► Branch along bronchial structures.
► Capillary exchange through diffusion.
► Lung Zones – see additional notes given by Mr. Holland
Alveoli
► Approximately 300 million alveoli – arranged in clusters of 15 – 20.
► Function: Gas exchange. – Acinus – cluster of alveoli
Alveolar Cells
► Type I alveolar cells:
 Structure. (protect against overloading of fluids)
 Fluid barrier.
► Type II alveolar cells:
 Surfactant.
► surface tension.
► Work of breathing.
► Type III alveolar cells:
 Macrophages. (cleaners)
Effect of Surfactant (decreases surface tension)
► Lipoprotein
► Facilitates expansion during inspiration
► Contain macrophage components
► Empties into lymphatics
Hypoxia
► Alveolar hypoxia pulmonary vasoconstriction.
 Pulmonary Shunting
► Blood that shunts by alveoli without picking up oxygen.
Anatomical Shunts:
 Blood moves from R  to L  without passing through the lungs.
Physiological Shunts:
 Blood is shunted past alveoli without picking up sufficient amounts of oxygen.
Ventilation-Perfusion (V/Q)
► Ventilation:
 Flow of gas in & out of lungs.
► Perfusion:
 Pulm. capillary blood flow.
► Gas Exchange:
 Depends on V/Q ratio.
► V/Q Balance:
 Ventilation = Perfusion (1:1).
► V/Q Imbalance:
 Ventilation < ≠ > Perfusion.
► Shunting.
V/Q Imbalance
► Physiological Shunt (Low V/Q Ratio):
 Pneumonia
 Atelectasis
 Tumors
 Mucous plug
► Alveolar Dead Space (High V/Q Ratio):
 PE
 Pulmonary Infarct
 Cardiogenic shock
 Mechanical vent.
► Silent Unit:
 Both ventilation & perfusion are decreased.
 Examples:
 Pneumothorax
 Severe ARDS
Oxygen Transport
► Oxygen-Hemoglobin Dissociation Curve
► Shift to the Right: acidotic
► Shift to the Left: alkalotic
Putting it together
Ventilation
-neurochemical control
-mechanics of breathing
- elasticity
-compliance
Perfusion
-gas exchange
-oxygen transport
-CO2 transport
-pulmonary circulation
Assessing Oxygenation
► SaO2 (Arterial O2 saturation):
 Hemoglobin O2 saturation.
► 97% is carried by Hgb.
 Normal > 95%.
► O2 Carrying Capacity:
 Hemoglobin: 12 – 18 g/dL.
► Tissue Perfusion (O2 Delivery):
 Cardiac Output (CO): 4 – 8 L/min.
 Heart Rate: 60 – 100 bpm.
 Stroke Volume: 55 – 100 ml/beat/m2.
► CO O2 delivered to tissues.
However, in normal conditions, approx. only 250 ml of O2 is used per minute.
► PaO2 / FiO2 Ratio:
 Normal Lung: > 400
 Acute Lung Injury: 200 – 300.
 ARDS: < 200 is significant.
Examples:
 PaO2 90 mmHg; FiO2 21% = 90 / 0.21 =
 PaO2 85 mmHg; FiO2 40 % = 85 / 0.40 =
 PaO2 80 mmHg; FiO2 80 % = 80 / 0.80 =