1. Gas Exchange and Respiratory Function Part One
By Linda Self

2. Review of Terms Cyanosis—influenced by polycythemia and anemia
Clubbing-Schamroth method
Hemoptysis
Perfusion—actual blood flow through the circulation
Ventilation----movement of gas into and out of the alveoli
Diffusion—oxygen and CO2 exchanged from
environment>trachea>bronchi>bronchioles and alveoli
Compliance-measure of the elasticity, expandability, and distensibility of lungs, influenced by surfactant

3. Ventilation—Perfusion Ratios
Normal lung is 1:1
Shunts: when perfusion exceeds ventilation, a shunt exists. Blood bypasses the alveoli w/o gas exchange occurring.
Pneumonia, atelectasis, tumors, mucous plugs

4. Ventilation-Perfusion Ratios cont.
High ventilation-perfusion ratio---Dead space
Ventilation exceeds perfusion
Alveoli do not have adequate blood supply for gas exchange to occur
Pulmonary emboli, pulmonary infarction, cardiogenic shock

5. Ventilation-Perfusion Ratios cont.
Silent unit—absence of ventilation and perfusion
Seen in pneumothorax and severe ARDS

6. Neurologic Control of Ventilation
Phrenic nerve
Respiratory center in medulla and pons
Central chemoreceptors in medulla, influenced by chemical changes in csf
Peripheral chemoreceptors in aortic arch and carotid arteries, respond first to changes in PaO2, then PaCO2 and pH

7. Gerontologic Considerations
Decreased strength of respiratory muscles
Decreased elasticity
Increased respiratory dead space
Decreased number of cilia
Decreased cough and gag reflex
Increased collagen of alveolar walls

8. Respiratory Assessment
Health History
Risk factors for respiratory disease-genetics, smoking, allergens, occupational and recreational exposure
Dyspnea, orthopnea
Cough, ?productive
Chest pain
Cyanosis
Lung sounds
Clubbing—indicates chronicity

9. Diagnostic Evaluation
PFTs-assess respiratory function, screening, assess response to therapy
FVC—vital capacity performed with a maximally forced expiratory effort
Forced expiratory volume—FEV1—volume of air exhaled in the specified time during the performance of forced vital capacity. FEV1 is volume exhaled in one second.
FEV1/FVC%--ratio of timed forced exp. volume to forced vital capacity

10. Diagnostic Evaluation--ABGs
1. pH
2. evaluate the PaCO2 and HCO3-
3. Look to see if compensation has occurred. If CO2 is >40, respiratory acidosis; If HCO3- <24, metabolic acidosis; next look at value other than primary disorder, if moving in same direction as primary value, compensation is underway.

11. ABG’s continued Can have two acid-base disturbances at same time
This can be identified when the pH does not explain one of the changes, e.g.,
pH 7.2
PaCO2 52
HCO3 13
Notice that oxygen level is not a component in determining the acid-base balance

12. ABGs cont.
Normal values for arterial gases: , CO mm Hg, HCO mEq/L, O mm Hg, BE +/-2 mEq/L
sat >94%
Mixed Venous Blood: , CO mm Hg, HCO mEq/L, O mmHg, BE +/- 2mEq/L, sat 60-80%
See chapter 14 of text

13. Acidosis
Results in decreased myocardial contractility and a decreased vascular response to catecholamines. May interfere with metabolism of certain medications

14. Alkalosis
Can radically impair oxygen release from RBCs. For this reason, use bicarbonate infrequently in code situations

15. Other diagnostic studies
Pulse oximetry—not reliable in severe anemia, high CO levels, or in shock
CO2 monitoring—tells us ventilation to lungs is occurring, that CO2 is being transported to lungs, exp. CO2 indicates adequate ventilation
Cultures
Imaging—chest xray, CT, MRI, lung scans (inject isotope, inhale radioactive gas), PET
Bronchoscopy
Thoracentesis
others

16. Sleep Apnea
Associated with frequent, loud snoring with breathing cessation for 10 seconds or long, at least 5 episodes per hour, followed by awakening by a snort when O2 levels drop
May be associated with obesity
Decreased pharyngeal tone (related to alcohol, sedatives, neuromuscular disease)

17. Sleep Apnea
Diagnosed by polysomnography (ECG, EEG, EMG, pulse oximetry)
More common in men
High risk for CAD, cerebrovascular disease and premature death.
Results in hypoxia and hypercapnia which trigger sympathetic response. Can lead to dysrhythmias and elevated BP

18. Sleep Apnea signs and symptoms
Excessive daytime sleepiness
Frequent nocturnal awakening
Insomnia
Loud snoring
Morning headaches
Personality changes
Systemic hypertension
Dysrhythmias
Pulmonary hypertension, cor pulmonale
polycythemia

19. Management Nurse educates patient Avoid alcohol and sedatives
Weight loss
CPAP or BiPAP—CPAP prevents airway collapse, BiPAP makes breathing easier and results in lower airway pressure
Uvulopalatopharyngoplasty
Tracheostomy
Provigil, Provera, Diamox, Triptil may help

20. Cancer of the Larynx Squamous cell most common—95% Increasing in women
More common in African Americans
Most common in individuals between years of age
Carcinogens—tobacco, alcohol, exposure to asbestos, wood dust, cement dust, tar products, leather and metals
Most often affects glottic area

21. Laryngeal Cancer Clinical manifestations
Hoarseness of greater than two weeks duration
Persistent cough
Sore throat
Dysphagia
Dyspnea
Ulceration
Foul breath
Cervical adenopathy
Weight loss
Debilitation

22. Assessment and Diagnosis
H&P
Laryngoscopy with biopsy/staging of disease
CT and MRI to assess adenopathy and further stageing

23. Laryngeal Cancer—Management
Depends on staging of tumor
Options include surgery, radiation and chemotherapy
Sometimes combination therapy
Ensure any dental problems corrected, usually before other treatments

24. Surgical Management
Laser surgery, supraglottic laryngectomy, hemilaryngectomy, total laryngectomy
In case of total laryngectomy, advanced cancer present
Laryngeal structures removed including portion of trachea. Results in permanent loss of voice and permanent tracheostomy
Often will have radical neck dissection involves removal of sternocleidomastoid muscle, lymph nodes, jugular vein, surrounding soft tissue

25. Post-operative Care Usually ICU postop
Monitor airway, VS, hemodynamic status and comfort level
Monitor for hemorrhage
Monitor for infection
Monitor tracheal stoma
Have extra trach at bedside (of same size!)

26. Post-operative Care May be on ventilator initially Will have trach
Ensure humidity at all times
May have split thickness skin graft or trapezius or pectoralis muscle grafts—ensure side of flap or graft not in dependent position
May have PCA
NG, G tube or jejunostomy tube may be in place—nutrition important
Speech rehab, esophageal speech, electrolarynges
Support group

27. Patients with chronic obstructive pulmonary disorders
COPD—nonreversible
Includes emphysema and chronic bronchitis
Can co-exist with asthma
Present with s/s in middle life and incidence increases with age
FVC and FEV1 decreased

28. Chronic Bronchitis Disease of airways
Increased mucous production, decreased ciliary activity, inflammation, reduced alveolar macrophage function

29. Emphysema
Lobule—physiologic unit of lung consisting of bronchiole and its branches (alveolar ducts, sacs and alveoli)
Two types—panlobar and centrilobular
In Panlobartype—destruction of bronchiole, alveolar duct and alveoli; little inflammation, hyperexpanded chest, work on exhalation
Centrilobar type—derangement of the V/Q ratios, chronic hypoxemia, hypercapnea, polycythemia and right sided heart failure
See p. 688 for schematic

30. Emphysema Risk factors include: Cigarette smoking
Occupational dusts, chemicals, pollution
Deficiency of alpha1-antitrypsin, protective enzyme that protects lung parenchyma from injury---seen in Caucasians

31. COPD clinical manifestations
Chronic cough, sputum production, and dyspnea on exertion (DOE)
Weight loss common
Increased number of respiratory infections
In primary emphysema, will have “barrel chest”

32. Diagnosis of COPD Thorough H&P
Spirometry to evaluate airflow obstruction
FEV1/FVC will be less than 70%
Reversibility will be tested
Chest xray
ABGs
Screening for alpha1-antitrypsin deficiency
Classified by five stages—0 through IV (see p. 690)

33. Medical Management Smoking cessation will slow progression
May use Chantix, Wellbutrin, nortriptyline, clonidine
Bronchodilators—beta agonists, anticholinergics, methyxanthines, combinations, nebulized medications, inhaled and systemic corticosteroids
Influenza and pneumococcal vaccines
Oxygen therapy—usually started in severe COPD
High fat, low CHO diet

34. Oxygen Therapy in COPD
Previously felt that high levels of O2 affected hypoxic drive
Now thought that Haldane effect relates to ability of hgb to carry O2 and CO2. With increased levels of O2, increased saturation, increased CO2 load w/o being able to expel it. So, increased hypercapnia.

35. Surgical Management
Bullectomy—have blebs or enlarged airspaces that do not contribute to ventilation
Lung volume reduction surgery—may improve quality of life but not life expectancy
Lung transplantation

36. Nursing Management Key is education Breathing exercises
Inspiratory muscle training—breathe against a set resistance
Activity pacing
Self-care activities
Physical conditioning
Oxygen tx
Nutritional therapy
Coping measures

37. Bronchiectasis
Chronic, irreversible dilation of the bronchi and bronchioles
Caused by: inflammation d/t recurrent infections damaging bronchial walls, thick sputum and decreased mucociliary clearance; genetic disorders like CF, idiopathic causes
Results in atelectasis, fibrosis, VQ mismatch
R/O TB or other pathology
Tx-chest PT, smoking cessation, continuous abx tx, possible surgical resection of affected areas

38. Asthma
Chronic inflammatory disease characterized by mucosal edema, airway hyperreactivity, and mucous production
Largely reversible
Allergy is strongest predisposing factor
Poorly controlled asthma can result in remodeling. Bronchial muscles and mucous glands enlarge, alveoli hyperinflate and subbasement fibrosis.

39. Asthma
Cells that play role in inflammation of asthma include: leukotrienes, bradykinins, prostaglandins, mast cells, neutrophils, eosinophils
Beta receptor stimulation results in decrease of chemical mediators and causes bronchodilation
Three most common symptoms of asthma are cough, dyspnea and wheezing

40. Asthma Family, environmental and occupational history is necessary
Comorbid conditions like GERD, drug- induced asthma and allergic bronchopulmonary aspergillosis may be present

41. Asthma Triggers Complications—status asthmaticus
Rescue and maintenance medications
Peak flow monitoring—measure highest airflow during a forced expiration. See asthma action plan on p Height, age and sex are variables to consider in personal best determination.

42. Status Asthmaticus
Severe and persistent asthma that does not respond to conventional therapy. Can be precipitated by infection, irritants, ASA or others
Severe bronchospasm with mucous plugging leading to asphyxia
Labored breathing, engorged neck veins, cough, wheezing
ABGs indicated
O2, IV fluids, burst of steroids, short acting corticosteroids, possibly magnesium sulfate
Nurse monitors, administers fluids and meds, ensures no irritants in environment

43. Atelectasis Closure of collapse of alveoli
Often occurs in postoperative setting and in those who are immobilized
Can result from any obstruction that blocks air to and from alveoli

44. Atelectasis
Clinical manifestations—cough, sputum, low grade fever. In severe cases, tachycardia, tachypnea, central cyanosis
Chest xray may reveal patchy infiltrates, crackles will be heard over affected area, O2 saturation may be lower than 90%

45. Atelectasis
Prevention—turning, mobilizing patient, deep breathing maneuvers, incentive spirometry, secretion management such as suctioning, nebulizers, chest PT
Management—IPPB, chest PT, nebulizer tx, bronchoscopy, possible ventilator support, thoracentesis

46. Pneumonia
Is an inflammation of the lung parenchyma caused by microorganisms
Community acquired—usually caused by: Strep pneumo, Hemophilus influenza, Legionella, Mycoplasma pneumoniae, Chlamydia, viral
Hospital acquired—Pseudomonas, Staph aureus, Klebsiella

47. Pneumonia
Pneumonia in the immunocompromised patient—Aspergillus, Pneumocystis, Mycobacterium tuberculosis
Aspiration pneumonia
Is the most infectious disease causing death in the United States

48. Pathophysiology of pneumonia
Arises when normal flora has been aspirated, when host defenses are down or from bloodborne organisms that enter the pulmonary circulation
Affects ventilation and diffusion—will have adequate perfusion but not ventilation

49. Risk factors for Pneumonia
Conditions resulting in mucous obstruction (cancer, smoking, COPD)
Immunosuppression
Prolonged immobility
Depressed cough
NPO, ETT, NG or OG tubes
Alcohol intoxication
Advanced age
Medications that depress respirations

50. Clinical Manifestations of Pneumonia
Not possible to diagnose a certain type by manifestations alone
May be sudden in onset with fever, chills and pleuritic pain as seen in pneumococcal pneumonia
May be gradual in onset with low grade fever, HA, pleuritic pain, myalgias and pharyngitis
Orthopnea
Purulent sputum

51. Diagnosis of Pneumonia
History
Physical exam
Sputum cultures
Blood cultures
Chest xray
Possible bronchoscopy depending on severity

52. Medical Management Antibiotic depending on Gram stain
Often treat empirically, intervene promptly
CAP-tx with Zithromax, Biaxin, doxy, or fluoroquinolone. With comorbidities, may use Augmentin, Vantin, Ceftin, and a macrolide or doxy. Symmetrel for Flu A, Tamiflu for Flu A/B. Bactrim for PCP.

53. Medical Management cont.
Hospital acquired—IV antibiotics such as second generation cephalosporins, carbapenems, fluoroquinolones. If MRSA, use vancomycin, Zyvox. For Pseudomonas, use Timentin, Unasyn, and an aminoglycoside.
Viral pneumonia is supportive care only.
Hydration is important in all types.

54. Other treatments Antihistamines Nasal decongestants Antipyretics
Monitoring O2 saturation, possibly ABGs
Serial xrays

55. Gerontologic Considerations
In elderly the classic s/s of cough, chest pain, sputum production and fever may be absent
May be difficult to distinguish heart failure from pneumonia
Xrays particularly helpful in this population

56. Nursing the patient with pneumonia
Frequent assessment—night sweats, fever, chills, cough, lung sounds
Encourage hydration as hydration thins and loosens secretions
Humidification w/or w/o oxygen
Encourage cough, chest physiotherapy
Promote rest
Maintain nutrition
Promote patient education

57. Respiratory Care Modalities
Nasal cannula—up to 6L/min. Delivers up to 42% oxygen
Simple mask—flow rate 6-8L/min. Delivers % oxygen.
Partial rebreather mask—flow rate is 8- 11L/min. Delivers 50-75% oxygen.
Nonrebreather mask—flow at 12 L/min. Delivers % oxygen.
Venturi mask—4-6 L/min, 6-8 L/min. Deliver respective oxygen concentration of 24, 26, 28 or 30, 35, 40% oxygen. Most accurate delivery.

58. Respiratory Care Modalities
Oxygen
Hypoxemia—decrease in arterial oxygen tension in blood
Hypoxia—decrease on oxygen supply to tissues
Oxygen toxicity—can occur if delivering >50% for longer than 48h. Caused by free radical production.
Signs/symptoms of oxygen toxicity— paresthesias, fatigue, refractory hypoxemia, alveolar atelectasis, alveolar infiltrates

59. Consider alveolar collapse with high levels of oxygen

60. Tracheostomy
Surgical procedure in which an opening is made into the trachea
Tracheostomy tube
Temporary or permanent
Used to bypass an upper airway obstruction, allow removal of tracheobronchial secretions, permit long term use of mechanical ventilation, to prevent aspiration in unconscious patient or to replace endotracheal tube

61. Complications of tracheostomy
Bleeding, pneumothorax, air embolism, aspiration, subcutaneous or mediastinal emphysema, recurrent laryngeal nerve damage
Airway obstruction from accumulation of secretions ,tracheoesophageal fistula, tracheal ischemia

62. Nursing Care of the Patient with Tracheostomy
Initially, semi-fowler’s position to facilitate ventilation, promote drainage, minimize edema, and prevent strain on the sutures
Allow method of communication
Ensure humidity to trach
Suction secretions as needed
Manage cuff—usually keep pressure less than 25 mm Hg but more than 15 mm Hg to prevent aspiration

63. Endotracheal Intubation
Pass ETT via nose or mouth into trachea
Method of choice in emergency situation
Passed with aid of a laryngoscope
ETT generally has a cuff, ensure that cuff pressure is between mm Hg.
Use warmed, humidified oxygen
Should not be used for more than 3 week

64. Preventing Complications Associated with Endotracheal and Tracheostomy Tubes
Administer adequate warmed humidity
Maintain cuff pressure at appropriate level
Suction as needed
Maintain skin integrity
Auscultate lung sounds—ETT can lodge in right mainstem bronchus
Monitor for s/s of infection
Monitor for cyanosis
Maintain hydration of patient
Use sterile technique when suctioning and performing trach care
Monitor O2 sat

65. Mechanical Ventilation
Used to control patient’s respirations, to oxygenate when patient’s ventilatory efforts are inadequate, to rest respiratory muscles
Can be positive pressure or negative pressure
Key for the nurse is assess patient—not the ventilator

66. Indications for Mechanical Ventilation
PaO2 <50 mm Hg with FiO2 >0.60
PaO2 >50 mm Hg with pH <7.25
Vital capacity < 2 times tidal volume
Negative inspiratory force < 25 cm H20
Respiratory rate > 35 bpm
( *vital capacity is dependent on age, gender, weight and body build. Usually is twice tidal volume. If < 10mL/kg, will need respiratory assist)

67. Classification of Ventilators—Negative Pressure
Used for patients with polio, muscular dystrophy, ALS, myasthenia gravis
Examples include the iron lung chamber, pneumo wrap and tortoise shell (portable devices with rigid shell to create a negative pressure)

68. Ventilators—positive pressure
Inflate lungs by exerting positive pressure on the airway
Usually requires trach or ETT
Used in home setting as well
Pressure cycled, time cycled and volume cycled
Noninvasive positive pressure ventilation is an option, does not require ETT

69. Positive Pressure Ventilators
Pressure cycled ventilators—delivers air until reaches a preset pressure, then cycles off, then passive expiration
Can vary as patient’s airway resistance or compliance changes
Volume delivered thus will vary and may compromise ventilation

70. Positive Pressure Ventilators
Time cycled rarely seen in adults (used in newborns and infants)
Volume cycled—most common. Delivers a preset volume usually 8-10ml per kg
Noninvasive positive pressure ventilation—CPAP and BiPAP. CPAP indicated for sleep apnea, BiPAP esp. useful to avoid intubating patients and in those with neuromuscular disorders, other conditions.

71. Ventilator Modes Assist control Intermittent mandatory control
Synchronized intermittent mandatory ventilation
Pressure support—assists SIMV, applies pressure plateau to spont. resp. during inspiratory phase
New modes incl. computerized systems

72. Initial Ventilator Settings
Tidal volume
Lowest concentration of oxygen to maintain PaO mm Hg
Peak inspiratory pressure
Mode—AC or SIMV, possibly PEEP
Sensitivity so that patient can trigger the vent. With minimal effort
Check ABGs after being on vent. for minutes

73. Remember………..
If patient becomes agitated, confused, tachycardic, blood pressure increases for some unexplained reason, assess for hypoxia and manually ventilate on 100%.
If patient’s heart rate slows and BP drops during suctioning, possible vagal stimulation. Stop suctioning and give 100% O2.

74. Bucking the ventilator
Occurs when the patient’s inspiration and expiration are out of synch with the ventilator
Anxiety, hypoxia, increased secretions, hypercapnia, others
Sedatives, muscle relaxants, paralytics may be necessary

75. Monitoring and Managing Potential Complications associated with the ventilator
See handout
Alterations in cardiac function
Barotrauma and volutrauma resulting in pneumothorax
Vagal stimulation
Pulmonary infections—use chlorhexidine gluconate in oral care

76. Weaning from the Ventilator—criteria for weaning
Vital capacity—amount of air expired after maximum inspiration. Should be mL/kg.
Maximum inspiratory pressure-used to assess the patient’s respiratory muscle strength—should be at least -20cm H20
Tidal volume—volume of air that is inhaled or exhaled during effortless breath.

77. Weaning criteria cont.
Minute ventilation—equals resp rate times tidal volume. Normal is 6 L/min.
PaO2 greater than 60 mm Hg with FiO2 <50%, stable vital signs, adequate nutritional status
Would refrain from sedating patient during weaning

78. Thoracic Surgeries Pneumonectomy Lobectomy Segmental resection
Lung volume reduction
others

79. Risk factors for thoracic surgery related atelectasis and pneumonia
Preop—age, obesity, poor nutritional status, smoking, preexisting lung disease, comorbid states
Intraoperative—thoracic incision, prolonged anesthesia
Postop—immobile, supine, inadequate pain management, prolonged intubation/ventilator, presence of NG tube, LOC, lack of education

80. Care of Patient after Thoracotomy
Maintain airway clearance
Positioning-lobectomy turn either side,pneumonectomy turn on affected side, segmental resection varies per doctor
Chest tube drainage/care
Relieve pain
Promote mobility
Maintain fluid volume and nutrition

81. Care of Patient after Thoracotomy—monitor and manage potential complications
Monitor respiratory status
Vitals
For dysrhythmias
For bleeding, atelectasis and infection
Monitor chest tube drainage, for leaks, for tube kinks, for excessive drainage

82. Chest tube drainage system
Based on three bottle system
Drainage chamber
Water seal
Wet or dry suction
Monitor water seal for bubbling
Check for subq emphysema
Gently milk tube
Occlusive dressing
Monitor drainage