Gas Exchange and Respiratory Function Part One

1
Gas Exchange and Respiratory FunctionPart One

• By Linda Self

2
Review of Terms

• Cyanosisinfluenced by polycythemia and anemia
• Clubbing-Schamroth method
• Hemoptysis
• Perfusionactual blood flow through the
  circulation
• Ventilation----movement of gas into and out of
  the alveoli
• Diffusionoxygen and CO2 exchanged from
• environmentgttracheagtbronchigtbronchioles and
  alveoli
• Compliance-measure of the elasticity,
  expandability, and distensibility of lungs,
  influenced by surfactant

3
VentilationPerfusion Ratios

• Normal lung is 11
• 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 unitabsence 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
• Clubbingindicates chronicity

9
Diagnostic Evaluation

• PFTs-assess respiratory function, screening,
  assess response to therapy
• FVCvital capacity performed with a maximally
  forced expiratory effort
• Forced expiratory volumeFEV1volume 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 gt40, respiratory acidosis If HCO3- lt24,
  metabolic acidosis next look at value other than
  primary disorder, if moving in same direction as
  primary value, compensation is underway.

11
ABGs 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 7.35-7.45, CO2
  35-45 mm Hg, HCO3 22-26 mEq/L, O2 80-100 mm Hg,
  BE /-2 mEq/L
• sat gt94
• Mixed Venous Blood 7.33-7.41, CO2 41-51 mm Hg,
  HCO3 22-26 mEq/L, O2 35-40 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 oximetrynot reliable in severe anemia,
  high CO levels, or in shock
• CO2 monitoringtells us ventilation to lungs is
  occurring, that CO2 is being transported to
  lungs, exp. CO2 indicates adequate ventilation
• Cultures
• Imagingchest 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 BiPAPCPAP 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 common95
• Increasing in women
• More common in African Americans
• Most common in individuals between 50-70 years of
  age
• Carcinogenstobacco, 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

• HP
• Laryngoscopy with biopsy/staging of disease
• CT and MRI to assess adenopathy and further
  stageing

23
Laryngeal CancerManagement

• 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 graftsensure side of flap
  or graft not in dependent position
• May have PCA
• NG, G tube or jejunostomy tube may be in
  placenutrition important
• Speech rehab, esophageal speech, electrolarynges
• Support group

27
Patients with chronic obstructive pulmonary
disorders

• COPDnonreversible
• 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

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Emphysema

• Lobulephysiologic unit of lung consisting of
  bronchiole and its branches (alveolar ducts, sacs
  and alveoli)
• Two typespanlobar and centrilobular
• In Panlobartypedestruction of bronchiole,
  alveolar duct and alveoli little inflammation,
  hyperexpanded chest, work on exhalation
• Centrilobar typederangement of the V/Q ratios,
  chronic hypoxemia, hypercapnea, polycythemia and
  right sided heart failure
• See p. 688 for schematic

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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

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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 HP
• 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 stages0 through IV (see p.
  690)

33
Medical Management

• Smoking cessation will slow progression
• May use Chantix, Wellbutrin, nortriptyline,
  clonidine
• Bronchodilatorsbeta agonists, anticholinergics,
  methyxanthines, combinations, nebulized
  medications, inhaled and systemic corticosteroids
• Influenza and pneumococcal vaccines
• Oxygen therapyusually 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

• Bullectomyhave blebs or enlarged airspaces that
  do not contribute to ventilation
• Lung volume reduction surgerymay improve quality
  of life but not life expectancy
• Lung transplantation

36
Nursing Management

• Key is education
• Breathing exercises
• Inspiratory muscle trainingbreathe 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
• Complicationsstatus asthmaticus
• Rescue and maintenance medications
• Peak flow monitoringmeasure highest airflow
  during a forced expiration. See asthma action
  plan on p. 715. 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 manifestationscough, 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

• Preventionturning, mobilizing patient, deep
  breathing maneuvers, incentive spirometry,
  secretion management such as suctioning,
  nebulizers, chest PT
• ManagementIPPB, chest PT, nebulizer tx,
  bronchoscopy, possible ventilator support,
  thoracentesis

46
Pneumonia

• Is an inflammation of the lung parenchyma caused
  by microorganisms
• Community acquiredusually caused by Strep
  pneumo, Hemophilus influenza, Legionella,
  Mycoplasma pneumoniae, Chlamydia, viral
• Hospital acquiredPseudomonas, Staph aureus,
  Klebsiella

47
Pneumonia

• Pneumonia in the immunocompromised
  patientAspergillus, 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 diffusionwill 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 acquiredIV 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 assessmentnight 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 cannulaup to 6L/min. Delivers up to 42
  oxygen
• Simple maskflow rate 6-8L/min. Delivers 40-60
  oxygen.
• Partial rebreather maskflow rate is 8-11L/min.
  Delivers 50-75 oxygen.
• Nonrebreather maskflow at 12 L/min. Delivers
  80-100 oxygen.
• Venturi mask4-6 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
• Hypoxemiadecrease in arterial oxygen tension in
  blood
• Hypoxiadecrease on oxygen supply to tissues
• Oxygen toxicitycan occur if delivering gt50 for
  longer than 48h. Caused by free radical
  production.
• Signs/symptoms of oxygen toxicityparesthesias,
  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-fowlers 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 cuffusually 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 15-20 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 soundsETT 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 patients respirations, to
  oxygenate when patients ventilatory efforts are
  inadequate, to rest respiratory muscles
• Can be positive pressure or negative pressure
• Key for the nurse is assess patientnot the
  ventilator

66
Indications for Mechanical Ventilation

• PaO2 lt50 mm Hg with FiO2 gt0.60
• PaO2 gt50 mm Hg with pH lt7.25
• Vital capacity lt 2 times tidal volume
• Negative inspiratory force lt 25 cm H20
• Respiratory rate gt 35 bpm
• ( vital capacity is dependent on age, gender,
  weight and body build. Usually is twice tidal
  volume. If lt 10mL/kg, will need respiratory
  assist)

67
Classification of VentilatorsNegative 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
Ventilatorspositive 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 ventilatorsdelivers air until
  reaches a preset pressure, then cycles off, then
  passive expiration
• Can vary as patients 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 cycledmost common. Delivers a preset
  volume usually 8-10ml per kg
• Noninvasive positive pressure ventilationCPAP
  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 supportassists 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 PaO2
  80-100 mm Hg
• Peak inspiratory pressure
• ModeAC or SIMV, possibly PEEP
• Sensitivity so that patient can trigger the vent.
  With minimal effort
• Check ABGs after being on vent. for 20-30 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 patients heart rate slows and BP drops during
  suctioning, possible vagal stimulation. Stop
  suctioning and give 100 O2.

74
Bucking the ventilator

• Occurs when the patients 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 infectionsuse chlorhexidine gluconate
  in oral care

76
Weaning from the Ventilatorcriteria for weaning

• Vital capacityamount of air expired after
  maximum inspiration. Should be 10-15mL/kg.
• Maximum inspiratory pressure-used to assess the
  patients respiratory muscle strengthshould be
  at least -20cm H20
• Tidal volumevolume of air that is inhaled or
  exhaled during effortless breath.

77
Weaning criteria cont.

• Minute ventilationequals resp rate times tidal
  volume. Normal is 6 L/min.
• PaO2 greater than 60 mm Hg with FiO2 lt50, 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

• Preopage, obesity, poor nutritional status,
  smoking, preexisting lung disease, comorbid
  states
• Intraoperativethoracic incision, prolonged
  anesthesia
• Postopimmobile, 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 Thoracotomymonitor 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