respiratory function

7/29/2019 Respiratory Function

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Gas Exchange and

Respiratory FunctionPart One


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Review of Terms

Cyanosisinfluenced by polycythemia andanemia

Clubbing-Schamroth method

Hemoptysis

Perfusionactual blood flow through thecirculation

Ventilation----movement of gas into and out ofthe alveoli

Diffusionoxygen and CO2 exchanged from

environment>trachea>bronchi>bronchioles andalveoli

Compliance-measure of the elasticity,expandability, and distensibility of lungs,influenced by surfactant


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VentilationPerfusion Ratios

Normal lung is 1:1

Shunts: when perfusionexceeds

ventilation, a shunt exists. Blood

bypasses the alveoli w/o gasexchange occurring.

Pneumonia, atelectasis, tumors,

mucous plugs


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Ventilation-Perfusion Ratios cont.

High ventilation-perfusion ratio---Deadspace

Ventilation exceeds perfusion

Alveoli do not have adequate blood

supply for gas exchange to occur

Pulmonary emboli, pulmonary

infarction, cardiogenic shock


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Ventilation-Perfusion Ratios cont.

Silent unitabsence of ventilationand perfusion

Seen in pneumothorax and severe

ARDS


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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 firstto changes in PaO2, then PaCO2 and

pH


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Gerontologic Considerations

Decreased strength of respiratorymuscles

Decreased elasticity

Increased respiratory dead space

Decreased number of cilia

Decreased cough and gag reflex

Increased collagen of alveolar walls


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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


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Diagnostic Evaluation

PFTs-assess respiratory function,screening, assess response to therapy

FVCvital capacity performed with amaximally forced expiratory effort

Forced expiratory volumeFEV1volume of air exhaled in the specifiedtime during the performance of forced

vital capacity. FEV1 is volume exhaled inone second.

FEV1/FVC%--ratio of timed forced exp.volume to forced vital capacity


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Diagnostic Evaluation--ABGs

1. pH

2. evaluate the PaCO2 and HCO3-

3. Look to see if compensation has

occurred. If CO2 is >40, respiratoryacidosis; If HCO3-


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ABGs continued

Can have two acid-base disturbances atsame 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


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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/Lsat >94%

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


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Acidosis

Results in decreased myocardialcontractility and a decreased vascular

response to catecholamines. May

interfere with metabolism of certainmedications


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Alkalosis

Can radically impair oxygen releasefrom RBCs. For this reason, use

bicarbonate infrequently in code

situations


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Other diagnostic studies

Pulse oximetrynot reliable in severeanemia, high CO levels, or in shock

CO2 monitoringtells us ventilation to lungsis occurring, that CO2 is being transported to

lungs, exp. CO2 indicates adequateventilation

Cultures

Imagingchest xray, CT, MRI, lung scans

(inject isotope, inhale radioactive gas), PET Bronchoscopy

Thoracentesis

others


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Sleep Apnea

Associated with frequent, loud snoringwith breathing cessation for 10

seconds or long, at least 5 episodes

per hour, followed by awakening by asnort when O2 levels drop

May be associated with obesity

Decreased pharyngeal tone (related toalcohol, sedatives, neuromuscular

disease)


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Sleep Apnea

Diagnosed by polysomnography(ECG, EEG, EMG, pulse oximetry)

More common in men

High risk for CAD, cerebrovasculardisease and premature death.

Results in hypoxia and hypercapnia

which trigger sympathetic response.Can lead to dysrhythmias and

elevated BP


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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


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Management

Nurse educates patientAvoid alcohol and sedatives

Weight loss

CPAP or BiPAPCPAP preventsairway collapse, BiPAP makesbreathing easier and results in lowerairway pressure

Uvulopalatopharyngoplasty

Tracheostomy

Provigil, Provera, Diamox, Triptil may

help


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Cancer of the Larynx

Squamous cell most common95% Increasing in women

More common in African Americans

Most common in individuals between50-70 years of age

Carcinogenstobacco, alcohol,

exposure to asbestos, wood dust,cement dust, tar products, leather andmetals

Most often affects glottic area


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Laryngeal Cancer

Clinical manifestations1. Hoarseness of greater than two weeks

duration

2. Persistent cough

3. Sore throat4. Dysphagia

5. Dyspnea

6. Ulceration

7. Foul breath8. Cervical adenopathy

9. Weight loss

10. Debilitation


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Assessment and Diagnosis

H&P

Laryngoscopy with biopsy/staging of

disease

CT and MRI to assess adenopathyand further stageing


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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


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Surgical Management

Laser surgery, supraglottic laryngectomy,hemilaryngectomy, total laryngectomy

In case of total laryngectomy, advancedcancer present

Laryngeal structures removed includingportion of trachea. Results in permanentloss of voice and permanenttracheostomy

Often will have radical neck dissectioninvolves removal of sternocleidomastoidmuscle, lymph nodes, jugular vein,surrounding soft tissue


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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!)


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Post-operative Care

May be on ventilator initially Will have trach

Ensure humidityat all times

May have split thickness skin graft ortrapezius or pectoralis muscle graftsensureside of flap or graft not in dependent position

May have PCA

NG, G tube or jejunostomy tube may be inplacenutrition important

Speech rehab, esophageal speech,electrolarynges

Support group


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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


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Chronic Bronchitis

Disease of airways

Increased mucous production,

decreased ciliary activity,

inflammation, reduced alveolarmacrophage function


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Emphysema

Lobulephysiologic unit of lungconsisting of bronchiole and its branches(alveolar ducts, sacs and alveoli)

Two typespanlobar and centrilobular

In Panlobartypedestruction ofbronchiole, alveolar duct and alveoli; littleinflammation, hyperexpanded chest,work on exhalation

Centrilobar typederangement of theV/Q ratios, chronic hypoxemia,hypercapnea, polycythemia and rightsided heart failure

See p. 688 for schematic


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Emphysema

Risk factors include:

1. Cigarette smoking

2. Occupational dusts, chemicals,

pollution

3. Deficiency of alpha1-antitrypsin,

protective enzyme that protects lung

parenchyma from injury---seen inCaucasians


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COPD clinical manifestations

Chronic cough, sputum production,and dyspnea on exertion (DOE)

Weight loss common

Increased number of respiratoryinfections

In primary emphysema, will have

barrel chest


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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 stages0 throughIV (see p. 690)


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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 insevere COPD

High fat, low CHO diet


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Oxygen Therapy in COPD

Previously felt that high levels of O2affected hypoxic drive

Now thought that Haldane effect

relates to ability of hgb to carry O2and CO2. With increased levels of O2,

increased saturation, increased CO2

load w/o being able to expel it. So,increased hypercapnia.


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Surgical Management

Bullectomyhave blebs or enlargedairspaces that do not contribute to

ventilation

Lung volume reduction surgerymayimprove quality of life but not life

expectancy

Lung transplantation


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Nursing Management

Key is education Breathing exercises Inspiratory muscle trainingbreathe

against a set resistanceActivity pacing Self-care activities Physical conditioning Oxygen tx Nutritional therapy Coping measures


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Bronchiectasis

Chronic, irreversible dilation of thebronchi and bronchioles

Caused by: inflammation d/t recurrentinfections damaging bronchial walls,

thick sputum and decreased mucociliaryclearance; 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


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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.


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Asthma

Cells that play role in inflammation ofasthma include: leukotrienes,bradykinins, prostaglandins, mastcells, neutrophils, eosinophils

Beta receptor stimulation results indecrease of chemical mediators andcauses bronchodilation

Three most common symptoms ofasthma are cough, dyspnea andwheezing


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Asthma

Family, environmental andoccupational history is necessary

Comorbid conditions like GERD, drug-

induced asthma and allergicbronchopulmonary aspergillosis may

be present


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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 arevariables to consider in personal best

determination.


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Status Asthmaticus

Severe and persistent asthma that does notrespond to conventional therapy. Can beprecipitated by infection, irritants, ASA orothers

Severe bronchospasm with mucous plugging

leading to asphyxia Labored breathing, engorged neck veins,

cough, wheezing

ABGs indicated

O2, IV fluids, burst of steroids, short actingcorticosteroids, possibly magnesium sulfate

Nurse monitors, administers fluids and meds,ensures no irritants in environment


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Atelectasis

Closure of collapse of alveoli Often occurs in postoperative setting

and in those who are immobilized

Can result from any obstruction thatblocks air to and from alveoli


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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 belower than 90%


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Atelectasis

Preventionturning, mobilizingpatient, deep breathing maneuvers,

incentive spirometry, secretion

management such as suctioning,nebulizers, chest PT

ManagementIPPB, chest PT,

nebulizer tx, bronchoscopy, possibleventilator support, thoracentesis


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Pneumonia

Is an inflammation of the lungparenchyma caused by

microorganisms

Community acquiredusually causedby: Strep pneumo, Hemophilus

influenza, Legionella, Mycoplasma

pneumoniae, Chlamydia, viral Hospital acquiredPseudomonas,

Staph aureus, Klebsiella


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Pneumonia

Pneumonia in theimmunocompromised patient

Aspergillus, Pneumocystis,

Mycobacterium tuberculosisAspiration pneumonia

Is the most infectious disease causing

death in the United States

P th h i l f


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Pathophysiology of

pneumoniaArises when normal flora has been

aspirated, when host defenses are

down or from bloodborne organisms

that enter the pulmonary circulationAffects ventilation and diffusionwill

have adequate perfusion but not

ventilation


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Risk factors for Pneumonia

Conditions resulting in mucousobstruction (cancer, smoking, COPD)

Immunosuppression

Prolonged immobility Depressed cough

NPO, ETT, NG or OG tubes

Alcohol intoxicationAdvanced age

Medications that depress respirations

Cli i l M if t ti f


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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 inpneumococcal pneumonia

May be gradual in onset with low

grade fever, HA, pleuritic pain,myalgias and pharyngitis

Orthopnea

Purulent sputum


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Diagnosis of Pneumonia

History Physical exam

Sputum cultures

Blood cultures

Chest xray

Possible bronchoscopy depending on

severity


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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. Symmetrelfor Flu A, Tamiflu for Flu A/B. Bactrim

for PCP.


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Medical Management cont.

Hospital acquiredIV antibiotics suchas second generation cephalosporins,

carbapenems, fluoroquinolones. If

MRSA, use vancomycin, Zyvox. ForPseudomonas, use Timentin, Unasyn,

and an aminoglycoside.

Viral pneumonia is supportive careonly.

Hydration is important in all types.


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Other treatments

Antihistamines Nasal decongestants

Antipyretics

Monitoring O2 saturation, possiblyABGs

Serial xrays


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Gerontologic Considerations

In elderly the classic s/s of cough,chest pain, sputum production and

fever may be absent

May be difficult to distinguish heartfailure from pneumonia

Xrays particularly helpful in this

population

Nursing the patient with


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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


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Respiratory Care Modalities

Nasal cannulaup to 6L/min. Deliversup 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 concentrationof 24, 26, 28 or 30, 35, 40% oxygen.Most accurate delivery.


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Respiratory Care Modalities

Oxygen Hypoxemiadecrease in arterial oxygen

tension in blood Hypoxiadecrease on oxygen supply to

tissues Oxygen toxicitycan occur if delivering

>50% for longer than 48h. Caused byfree radical production.

Signs/symptoms of oxygen toxicityparesthesias, fatigue, refractoryhypoxemia, alveolar atelectasis, alveolarinfiltrates


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Consider alveolar collapse with highlevels of oxygen


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Tracheostomy

Surgical procedure in which an openingis made into the trachea

Tracheostomy tube

Temporary or permanent

Used to bypass an upper airwayobstruction, allow removal oftracheobronchial secretions, permit long

term use of mechanical ventilation, toprevent aspiration in unconsciouspatient or to replace endotracheal tube

Complications of


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Complications of

tracheostomy Bleeding, pneumothorax, air

embolism, aspiration, subcutaneous or

mediastinal emphysema, recurrent

laryngeal nerve damageAirway obstruction from accumulation

of secretions ,tracheoesophageal

fistula, tracheal ischemia

Nursing Care of the Patient with


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Nursing Care of the Patient with

Tracheostomy Initially, semi-fowlers position to

facilitate ventilation, promote drainage,

minimize edema, and prevent strain

on the suturesAllow 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

E d h l I b i


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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

P ti C li ti A i t d ith


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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 inright 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


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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

Indications for Mechanical


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Indications for Mechanical

Ventilation

PaO2 0.60 PaO2 >50 mm Hg with pH 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)

Classification of Ventilators


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Classification of Ventilators

Negative Pressure

Used for patients with polio, musculardystrophy, ALS, myasthenia gravis

Examples include the iron lung

chamber, pneumo wrap and tortoiseshell (portable devices with rigid shell

to create a negative pressure)


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Ventilatorspositive pressure

Inflate lungs by exerting positivepressure on the airway

Usually requires trach or ETT

Used in home setting as well Pressure cycled, time cycled and

volume cycled

Noninvasive positive pressureventilation is an option, does not

require ETT


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Positive Pressure Ventilators

Pressure cycled ventilatorsdeliversair 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 andmay compromise ventilation


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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.


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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


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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


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Remember..

If patient becomes agitated, confused,tachycardic, blood pressure increases

for some unexplained reason, assess

for hypoxia and manually ventilate on100%.

If patients heart rate slows and BP

drops during suctioning, possiblevagal stimulation. Stop suctioning and

give 100% O2.


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Bucking the ventilator

Occurs when the patients inspirationand expiration are out of synch with

the ventilator

Anxiety, hypoxia, increasedsecretions, hypercapnia, others

Sedatives, muscle relaxants,

paralytics may be necessary

Monitoring and Managing


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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

Weaning from the Ventilator


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Weaning from the Ventilator

criteria for weaning

Vital capacityamount of air expiredafter maximum inspiration. Should be

10-15mL/kg.

Maximum inspiratory pressure-used toassess the patients respiratory

muscle strengthshould be at least -

20cm H20 Tidal volumevolume of air that is

inhaled or exhaled during effortless

breath.


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Weaning criteria cont.

Minute ventilationequals resp ratetimes tidal volume. Normal is 6 L/min.

PaO2 greater than 60 mm Hg with

FiO2


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Thoracic Surgeries

Pneumonectomy Lobectomy

Segmental resection

Lung volume reduction

others

Risk factors for thoracic surgery


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g y

related atelectasis and

pneumonia Preopage, obesity, poor nutritional

status, smoking, preexisting lung

disease, comorbid states Intraoperativethoracic incision,

prolonged anesthesia

Postopimmobile, supine, inadequatepain management, prolonged

intubation/ventilator, presence of NG

tube, LOC, lack of education

Care of Patient after


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Care of Patient after

Thoracotomy

Maintain airway clearance Positioning-lobectomy turn either

side,pneumonectomy turn on affected

side, segmental resection varies perdoctor

Chest tube drainage/care

Relieve pain Promote mobility

Maintain fluid volume and nutrition

Care of Patient afterTh t it d


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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

Ch t t b d i t


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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

M it d i

respiratory function

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