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Gas Exchange Chapter 67 and 32 Acute Respiratory Failure Overview โ Occurs when oxygenation, ventilation, or both are inadequate โ Insufficient O2 transferred to blood โ Hypoxemia โ Decreased PaO2 (shows up in ABGs) and SaO2 (oxygenation in the blood, pulse oximetry) โ Inadequate Co2 removal โ Hypercapnia โ Increased PacCo โ Assessed by arterial blood gases (ABGs) and pulse oximetry Acute Respiratory Failure โ No a disease but a symptom that reflect lung function โ Result of one or more disorders involving lungs or other body systems โ Respiratory system โ pancreatitis โ Cardiac system โ Heart failure โ Central nervous system โ Overdose, sleeping pills, narcotics โ Neuromuscular system โ MS โ Chest wall alteration โ Pneumothorax Acute Respiratory Failure โ Occurs when oxygenation and/or ventilation are inadequate โ Classified as two types โ Hypoxemic: oxygenation failure- inadequate O2 transfer โ Hypercapnic: ventilatory- inadequate CO2 removal โ May have both types at the same time ARF โ Patients can have both types of respiratory failure at the same time: acute-on-chronic โ Changes in PaO2 and PaCO2 may develop over several minutes, a few hours, or a day or two โ May also have hemodynamic instability (Increased HR, decreased BP), increased respiratory effort, and decreased level of consciousness requiring immediate intervention โ Chronic respiratory failure develops more slowly over days to weeks; generally more stable with compensatory changes
Hypoxemic Respiratory Failure โ VQ mismatch is an imbalance between perfusion and ventilation โ Shunting- blood crosses from right heart to left without being oxygenated โ Diffusion limitation occurs when oxygen transport across the alveolocapillary membrane is impaired (Pulmonary Edema) โ Alveolar hypoventilation causes the bodyโs carbon dioxide level to rise (Central apnea) Hypoxic Respiratory Failure โ Ventilation-perfusion (V/Q) mismatch โ Normal alveolar ventilation = 4-6L โ Pulmonary blood flow = 4-6 L/min โ VQ ratio = 0.8-1. โ Ideally, V/Q ratio 1:1 or V/Q equals 1 โ V/Q mismatch occurs when ratio is not 1: โ Regional mismatches occur normal โ Apex- more ventilation than perfusion โ Bases- less ventilation than perfusion โ Net effect is a close match โ Diseases and conditions cuaging VQ mismatch
โ Increases PaO2 at normal gas exchange unit โ Mixes with poorly oxygenated blood from damaged areas โ Overall increases PaO โ Best therapy is to treat the underlying cause Hypoxemic Respiratory Failure โ Shunt: blood leaves the heart without gas exchange- extreme V/Q mismatch โ Anatomic shunt (heart) - ventricular septal defect โ Intrapulmonary shunt โ Blood flows through pulmonary capillaries without exchanging gases โ See when alveoli fil with fluid, for example, pneumonia โ Oxygen therapy alone ineffective for hypoxemia; need mechanical ventilation with high FiO HRF โ Diffusion limitation โ Occurs when the oxygen transport across the alveolocapillary membrane is impaired. Diffusion limitation may be due to decrease in lung surface area for diffusion, inflammation, and fibrosis of the alveolocapillary membrane, low alveolar oxygen, and extremely short capillary transit time. Alveolar-capillary membrane is thicker (fibrotic) and slows gas exchange โ Diffusion limitation โ Pulmonary fibrosis โ Interstitial lung disease โ ARDs โ Pulmonary edema โ Hypoxemia present during exercise โ Alveolar hypoventilation โ Decreased ventilation leading to increased PaCo โ Mainly a mechanism of hypercapnic respiratory failure but contributes to hypoxemia โ CNS conditions โ Chest wall dysfunction โ Acute asthma โ Restrictive lung diseases HRF โ Interrelationship of mechanisms โ Usually a combination fo 2 or more factors โ V/Q mismatch โ Shunt โ Diffusion limitation โ Alveolar hypoventilation
โ Most common โ Other factors that increase O2 demand โ Anxiety โ Unrelieved pain Hypoxemic Manifestations โ Dyspnea โ Tachypnea โ Prolonged expiration โ Nasal flaring โ Intercostal muscle refraction โ Use of accessory muscles โ Decreased Spo โ Paradoxical chest movements โ Cyanotic โ Agitation โ Confusion โ Delirium โ Tachycardia โ Hypertension โ Fatigue Hypoxemic Manifestations โ Hypoxia: signs and symptoms of inadequate oxygenation โ If severe, cells shift from aerobic to anaerobic metabolism, increasing lactic acid and causing metabolic acidosis (if not buffered with sodium bicarbonate); this leads to tissue and cell dysfunction and death (if not corrected) Hypercapnic Respiratory Failure โ Ventilatory failure โ CO2 levels cannot be maintained within normal limits due to: โ An increase in CO2 production โ Or โ A decrease in alveolar ventilation โ Acute (asthma) or chronic (COPD) Hypercapnic Respiratory Failure โ Conditions causing impaired ventilation โ CNS problems โ Neuromuscular conditions โ Chest wall abnormalities โ Conditions affecting the airways and/or alveoli โ CNS problems โ Suppress the drive to breath
โ Severe obesity โ Thoracic trauma โ ALS โ Guillain Barre syndrome โ MS/MG/Muscular Dystrophy โ Toxin exposure Hypercapnic Manifestations โ Dyspnea โ Use of tripod position โ Pursed lip breathing โ Limited chest wall movement โ Paradoxical breathing โ Decreased respiratory rate โ Rapid respiratory rate with shallow breathing โ Decreased tidal volume โ Morning headache โ Disorientation โ Confusion โ Agitation โ Increased ICP (CO2- vasodilation-ICP) โ Dysrhythmias โ Hypertension (increased cardiac workload-HTN) โ Muscle weakness Clinical Manifestations Respiratory Failure โ Sudan or gradual onset โ A sudden decrease in PaCO2 or rapid increase in PaCO2 implies a serious condition or life threatening emergency โ Signs of respiratory failure are related to โ Extent of changes in PaO2 or PaCo โ Speed of change โ Ability for compensation to occur โ Failure of compensatory mechanisms leads to respiratory failure โ Frequent assessment is a priority โ First sign of respiratory failure is a change in mental status โ Decreased O2 - restlessness, confusion, agitation โ Increased CO2- morning headache, decreased RR< and decreased LOC โ Early signs: heart an lungs trying to compensate โ Tachycardia, tachypnea, and mild HTN โ Late Sign โ Cyanosis (unreliable indicator)
โ PaO2 less than or equal to 45 mm Hg โ Priority: immediate assessment of ability to breath and provide assistive measures โ May require intubation and mechanical ventilation Clinical Manifestations Observe โ Position: lie down, sit upright, or tripod โ Work of breathing: effort needed by respiratory muscles ot inhale air into the lungs โ Breathing patterns โ Rapid, shallow (hypoxemia); monitor for fatigue โ Slow RR (hypercapnia) โ Change from rapid to slow RR indicating severe muscle fatigue Ability to speak โ 2 to 3 word dyspnea โ Pursed lip breathing โ Increased expiratory time; prevents small bronchial collapse Clinical Manifestations โ Retraction of intercostal spaces or supraclavicular area; use of accessory muscles โ Paradoxical breathing โ Abdomen and chest move outward with exhalation and inward with inhalation (opposite of normal) โ May be diaphoretic from increased WOB โ Auscultate breath sounds โ Fine crackles; fluid in airways โ Absent or diminished; atelectasis, pneumonia, or hypoventilation โ Bronchial; consolidation โ Pleural friction rub; pneumonia involving pleura Diagnostic Studies โ Chest x ray โ Helps find the cause โ ABG analysis โ Determines oxygenation โ Pulse oximetry โ Labs โ CBC โ Electrolytes โ Urinalysis โ Hemodynamic monitoring- CVP/SV/PAWP/SVCO2/SVO Nursing Management โ Management and care will vary. Factors to consider: โ Age
โ Never withhold oxygen form a hypoxic patient โ Observe response and monitor for changes in mental status, RR, and ABGs โ Oxygen therapy โ Delivery system should โ Be tolerated by the patient โ Maintain PaO2 at 55 to 60 or more and SaO2 at 90% or more at lowest o concentration possible โ Patient may not tolerate face mask, may need to choose another option โ Claustrophobia; patient may try to remove mask โ Oxygen therapy โ High FiO2 for prolonged periods can lead to adverse effects โ Oxygen toxicity (greater than 60% O2 for greater than 48 hours) โ Increased pulmonary capillary permeability โ Decreased surfactant production or inactivation โ Fibrotic changes in the alveoli โ Chronic hypercapnia, for example, COPD patients โ High CO2 levels do not act as respiratory stimulant โ Provide O2 at low โ Consider mechanical ventilation with inadequate response โ Mobilization of secretions โ Secretions can block or limit the exchange of gases, leading to ARF or exacerbation of ARF โ Secretions can be mobilized by โ Patient positioning โ Effective coughing โ Chest physiotherapy โ Suctioning โ Humidification โ hydration โ Patient positioning โ HOB should be raised to al least 30 degrees; reclining chair or chair bed โ Increases respiratory expansion, decreases dyspnea, and mobilize secretions โ risk of aspiration: use side lying position โ Unilateral lung disorders โ Lateral or side lying position; โgood lung downโ to improve V/Q matching by draining secretions to remove with suctioning โ Bilateral lung disorders โ Reposition at regular intervals on both sides โ Effective coughing โ Clears secretions; less tiring
โ Augmented coughing (quad coughing) โ Place one or both hands at anterolateral base of lungs; have patient take a deep breath and move hands forcefully up as expiration begins โ f โ Postural drainage โ Percussion โ Vibration โ Contraindicated with TBI, unstable orthopedic injuries, and recent hemoptysis โ Suctioning โ Artificial airway โ Posterior oropharyngeal โ Monitor for complications: hypoxia, increased ICP, dysrhythmias, hypotension, HTN and tachycardia, and bradycardia โ Humidification thin secretions โ Aerosols of sterile normal saline or mucolytic drugs via nebulizer โ O2 via aerosol ask โ Monitor for bronchospasm and severe coughing โ Hydration โ Oral intake 2 to 3 L/day (unless contraindicated) โ IV fluids โ Monitor for fluid overload โ Noninvasive PPV โ Provides O2 and decreases WOB with spontaneous breathing; be awake, alert, and VS stable โ Contraindicated for decreased LOC, high O2 requirements, facial trauma, hemodynamic instability, or excess secretions โ Two forms โ CPAP- continuous positive airway pressure โ BIPAP- bilevel positive airway pressure โ Nutritional therapy โ Collaboration with dietician โ Maintain protein and energy stores โ Critically ill: hypermetabolic state โ Start enteral or parenteral nutrition within 24 to 48 hours to avoid depletion and delayed recovery โ Drug Therapy โ Goals of drug therapy: โ Reduce airway inflammation and bronchospasm โ Relieve pulmonary congestions
โ Tracheostomy Collar and T-piece โ Venturi Mask โ Precise, high flow rate delivery of O โ Helpful for low, constant O2 administration โ High Flow Nasal Cannula โ Blends O2 with compressed air โ Aminsers up 60 L/min of O Mobilization of Secretions โ Positioning โ Upright, elevate head of the bed 30 degrees or use reclining chair โ Sitting position is best โ If patient is aspiration risk, side-lying is preferred โ One side-lying lung disorders โ Position in lateral or side-lying positon โgood lung downโ โ Allows draining of secretions โ Effective coughing and deep breathing โ Chest physiotherapy โ Suctioning โ Humidification โ Hydration โ Keeps secretions thin and easily moveable Positive Pressure Ventilation โ Used if initial measures are insufficient โ Mask is placed over patientโs nose and mouth โ Mechanical ventilator delivers PPV to the patient โ CPAP and BiPAP โ BiPAP is commonly used for ARF โ Two different levels of positive pressure Drug Therapy โ Reduce Inflammation โ IV corticosteroids โ Methylprednisolone โ Inhaled corticosteroids โ Albuterol โ albuterol/ipratropium (DuoNeb) โ Salmeterol โ Formoterol โ fluticasone/salmeterol (Advair) โ budesonide/formoterol (symbicort) โ Relieve congestion
โ Furosemide (Lasix) โ Morphine โ Nitroglycerin โ Reduce discomfort โ Benzodiazepines โ opioids Other Respiratory Treatments โ Relieve pulmonary Congestion โ Treat infection โ Reduce anxiety, pain, and restlessness โ Nutritional therapy โ Optimal caloric intake for hypermetabolic states โ TPN, PN, enteral nutrition (started with 24-48 hours) โ Use Central line only to give it or a single lumen PICC line
- Which patient is at highest risk for hypoxemic respiratory failure? a) A patient who has a massive pulmonary embolism
- Nurse Taking care of 4 patients in critical care, which patient to see first? a) A 65 year old female with a fever and an ABG results of PaO2 of 58
- Albuterol causes all these side effects except a) Hypertension b) Bradycardia c) Tachycardia d) Arrhythmias
- The nurse is providing education to a patient with COPD. Which statement shows additional needed teaching? a) I should use my long acting beta agonist when I have an exacerbation
- Which diagnostic test would provide the nurse with the most specific information to evaluate the effectiveness of interventions fr a) Arterial blood gas
- A patient with respiratory failure is increasingly lethargic, with a respiratory rate of 6 bpm and an oxygen saturation of 78%. Which intervention woul the nurse anticipate a) Endotracheal intubation and positive pressure ventilation
- A nurse is caring for a patient with right lower lobe pneumonia who is obese. Which position will provide the best gas exchange? a) On the left side
- The nurse is admitting a patient with possible respiratory failure and a high PaCO2, which assessment information would the nurse report asap to the MD? a) The patients appears somnolent
