Respiratory - Pneumonia, Aspiration, ARDS/ALI

Pneumonia - what is it?

• an acute inflammation of the lung parenchyma (caused by an infectious agent) that can lead to alveolar consolidation

  • CAUSATIVE AGENTS - bacterial, viral, fungal, parasitic

Pneumonia - community acquired pneumonia (CAP)

• OUTSIDE the hospital

• common pathogens - Streptococcus pneumoniae, Legionella pneumophila, Klebsiella pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Mycoplasma pneumoniae, Pseudomonas aeruginosa

Pneumonia - hospital acquired pneumonia (HAP)

• pneumonia that developed in acute care, long-term care, or a nursing home

Pneumonia - ventilator associated pneumonia

• develops 48 hours or more after admission to the hospital

• common pathogens: P. aeruginosa, E. coli, K. pneumoniae, Acinetobacter baumannii, S. aureus (especially diabetes and head trauma), MRSA

• HIGHER MORTALITY THAN COMMUNITY ACQUIRED PNEUMONIA

Pneumonia - risk factors

• age

• preexisting pulmonary disease

• smoking

• decreased LOC

• artificial airways

• chronic illness

• malnutrition

• immunocompromised

• increased secretions

• atelectasis

• immobility

• depressed cough or gag reflex

• concurrent antibiotic therapy

• aspiration

• organisms spread from another site (gut, wound) to the lungs

• multiple organ dysfunction syndrome (MODS)

Pneumonia - signs and symptoms

• chills, diaphoresis, fever, malaise

• tachycardia, chest pain

• confusion (ESPECIALLY OLDER ADULTS)

• productive cough

• use of accessory muscles

• dehydration

• over area of consolidation on chest:

  • INCREASED tactile fremitus (how well sound is transmitted through the lungs)

  • dull to percussion

  • bronchial breath sounds or diminished breath sounds

  • bronchophony (louder/clearer)

  • egophony (“e” to “a”)

  • whispered pectoriloquy (whisper heard better with a stethoscope)

Pneumonia - DIAGNOSIS

• CXR: consolidation or diffuse patchy infiltrates

• sputum culture with Gram stain

• blood cultures

• WBC: high but may be normal or low in immunocompromised or elderly people

• WBC differential: increased bands >10%

• ABGs - hypoxemia

• thoracentesis for effusions

Pneumonia - treatments

• optimize oxygenation/ventilation → titrate FiO2

• POSITIONING - GOOD lung DOWN

  • bronchial hygiene, chest physiotherapy

  • prone positioning for severe hypoxemia

  • noninvasive ventilation or intubation/mechanical ventilation as needed

  • bronchoscopy (with lavage, if needed)

  • mobilize, clear secretions

• identify organisms → sputum culture/sensitivity; blood cultures

• antibiotic therapy

• system support (hydration, fever management, glucose control, nutrition)

• general preventative measures (smoking cessation, pneumonia vaccine for those who are 65 and older; flu vaccine)

Pneumonia - antibiotic therapy (empiric therapy, timing, organism-specific therapy)

• empiric therapy - choice of agent is based on the likely causative organism (as determined by a patient assessment and the types of pneumonia seen in the community and in the institution) and whether that organism may be resistant to therapy

• timing - first dose within 4 hours if the patient first presents to the ED (and is later admitted to the hospital); the first ABX dose should be given in the ED

• organism-specific therapy - AS SOON AS THE RESULTS OF THE CULTURE AND SENSITIVITY ARE AVAILABLE

Pneumonia - PREVENTION of Hospital-Acquired Pneumonia

• practice hand hygiene

• keep HOB elevated 30 degrees or more

• prevent bacterial translocation from GI tract: use the gut, feed the patient

• practice oral hygiene

• provide education on common institution pathogens and the rates of nosocomial pneumonia

• use evidence-based confirmation of feeding tube placement (confirm with x-ray prior to using for feeding; mark exist site with marker; assess patency Q4; observe for change in length; review routine chest/abd xrays; observe changes in volume of aspirate; use pH strips; observe appearance of feeding tube aspirates)

Pneumonia - PREVENTION OF VENTILATOR-ASSOCIATED PNEUMONIA

• drain accumulated condensate from tubing

• prevent backflow of tubing condensate into ETT

• change ventilator tubing only when it is contaminated

• mobilize the patient

• utilize aseptic technique for ETT, tracheostomy suctioning

• adhere to mouth care protocol, chlorhexidine mouth rinse

• brush teeth to remove plaque

• keep ETT cuff inflated

• perform subglottic suctioning prior to cuff deflation

• perform routine oropharyngeal suctioning

Aspiration - what is it?

• the inhalation of toxic substances into the lung, with an injury to the lung that is the result of the chemical, mechanical, and/or bacterial characteristics of aspirate

  • oropharyngeal is most common; may or may not involve an infection; may be acute or chronic; micro or massive

Aspiration - emergent management (witnessed vs. ALL aspirations)

• witnessed - place patient in slight trendelenburg and turned to the RIGHT side to aid drainage; suction mouth and pharyngeal areas; bronchoscopy for large particles

• ALL aspirations - O2 (titrate as needed); intubation/mechanical ventilation as needed; monitor for the onset of noncardiogenic pulmonary edema (ARDS) or pneumonia; monitor for decreased BP

Aspiration - why do we turn the patients to the right for a witnessed aspiration?

• due to the anatomy of the right mainstem bronchus (shorter, wider, and with less of an angle), most aspirations occur in the RIGHT lung

  • the GOAL is to keep the aspiration from spreading/protect the airway!!

Aspiration - ETIOLOGIES

• altered LOC

• drug or alcohol abuse

• depressed gag, cough, or swallowing reflexes

• presence of feeding tubes (ALL TYPES)

• improper patient positioning

• presence of artificial airways

• ileus or gastric distension

• history of dysphagia, GERD, esophageal strictures, decreased GI motility

• increased secretions

Aspiration - signs and symptoms

• acute respiratory distress

• presence of gastric contents in oropharynx

• tachycardia

• hypoxemia

• crackles

• copious secretions due to alveolar edema

• hypotension (massive fluid shifts may occur)

ARDS/ALI - what are they?

• syndromes caused by acute conditions that trigger an inflammatory response, resulting in an increase in permeability of pulmonary capillary membranes, allowing transudation of proteinaceous fluid into interstitial/alveolar spaces

  • “NONcardiogenic pulmonary edema”

  • DAMAGE to type II alveolar cells is one of the pathological consequences, as these are the cells that are responsible for production of surfactant → MASSIVE ATELECTASIS!!

ARDS/ALI - both involve a shunt. What does this MEAN? what is NEEDED to help with this?

• pathologic shunting → blood goes through the lungs but does NOT get oxygenated, resulting in refractory hypoxia (FiO2 is increased to the maximum 100% and hypoxemia is still present)

  • PEEP needs to be provided in order to increase alveolar recruitment/prevents alveolar collapse and treat the refractory hypoxemia

ARDS/ALI - differentiation with PaO2/FiO2 ratio

• ARDS - less than OR equal to 200 mmHg regardless of PEEP level

• ALI - between 201 and 300 mmHg regardless of PEEP level

ARDS/ALI - PaO2/FiO2 examples

• patient receiving 50% FiO2 and PaO2 is 90

  • 90 / 0.50 = 180

ARDS/ALI - what is surfactant? why is it important?

• phospholipid/lipoprotein produced by Type II alveolar cells that stabilizes alveoli by keeping them open

• helps increase lung compliance/eases work of breathing

• ARDS - type II alveolar cells are destroyed, resulting in massive atelectasis/alveolar collapse, decreased compliance, INCREASED WOB, and decreased functional residual capacity (decreased amount of air remaining in lungs after normal exhalation)

ARDS/ALI - PATHOPHYSIOLOGY

• DIFFUSE alveolar-capillary membrane injury (inflammatory response)

  • →damage to Type II alveolar cells → decreased surfactant → ALVEOLAR COLLAPSE/decreased FRC/lung compliance → HYPOXEMIA

  • →damage to capillary endothelial cells → capillary leak →alveolar edema/pulmonary interstitial edema → diffusion defect → ALVEOLAR COLLAPSE/HYPOXEMIA

ARDS/ALI - ETIOLOGIES (direct vs. indirect)

• direct

  • aspiration; pneumonia, pulmonary contusion, fat/air embolism, O2 toxicity, inhalation injury, drowning, transthoracic radiation

• indirect

  • sepsis, shock, head injury, non-thoracic trauma, blood transfusion, pancreatitis, burns, heart bypass, DIC

ARDS/ALI - EARLY signs/symptoms

• tachycardia

• apprehension/restlessness

• mild dyspnea

• respiratory ALKALOSIS (breathing fast)

• few crackles

• chest x-ray → isolated infiltrate or “ground glass” appearance

• PaO2 on room air ABOUT 60 mmHg

ARDS/ALI - LATE signs/symptoms

• tachycardia, episodes of bradycardia

• agitation

• extreme dyspnea

• respiratory and metabolic acidosis

• crackles/wheezes

• chest x-ray → whiteout/bilateral infiltrates

• PaO2 on room air ABOUT 30 mmHg, refractory hypoxemia despite INCREASED FiO2

ARDS/ALI - TREATMENTs (pulmonary stabilization strategies)

• intubation with mechanical ventilation

• PEEP, usually 15 cm H2O or greater; monitor for barotrauma and decreased cardiac output; treat hypotension, but do NOT discontinue PEEP

  • NOTE: disconnection of the ventilator circuit and PEEP will result in alveolar derecruitment and hypoxemia that may not be readily corrected

• limit plateau pressure to 30 cm H2O or less

• limit tidal volume (Vt) to 5-6 mL/kg → “permissive hypercapnia” to prevent volutrauma

  • a low Vt will cause a rise in the PaCO2 and a drop in the pH; however, patients tend to tolerate a pH as low as 7.2

ARDS/ALI - TREATMENTS (cardiovascular strategies / other treatments)

• cardiovascular stabilization (support BP (fluids, vasopressors, especially when ARDS is due to septic shock); monitor for arrhythmias

• prone positioning (helps deliver blood flow to underperfused lung units, thereby improving ventilation/perfusion; keeps alveolar lung units open, thus improving gas exchange and preventing further injury (USE EXTREME CAUTION to avoid misplacement/loss of airway; prevent a pressure injury)

• monitor acid-base balance

• DVT/stress ulcer prophylaxis

• analgesia/sedation

• nutritional support

• nitric oxide, prone positioning may provide improvement in oxygenation

• coordinate interdisciplinary team - PT, OT, dietitian

• prevent, identify organ failure

• emotional support

• monitor for complaications

• NO STEROIDS!! (except for select patients with Covid-19 pneumonia)

ARDS/ALI - COMPLICATIONS

• usually die from multiple organ dysfunction syndrome, as well as….

  • secondary infections

  • pulmonary embolus

  • ileus

  • skin breakdown

  • malnutrition

  • barotrauma → pneumothorax, subcutaneous emphysema