Critical Pulmonary Dysfunction

acute respiratory failure (ARF)

• Inadequate gas exchange

• The hallmark of ARF is HYPOXEMIA

• Most common organ failure in ICUs

• Mortality rate = 22-75%

assessment and diagnosis of ARF

• Tachycardia, tachypnea, use of accessory muscles, nasal flaring, fear, grunting, restless

• Any patient who presents confusion, agitation, or restless must be assessed for:

  • DO NOT TREAT UNTIL: hypoxemia first! And hypoglycemia! And urinary retention

• PaO2 < 60/ SaO2 < 90% or PaCO2 > 50 with acidosis

management of ARF

• Supplemental O2 therapy

  • Goal is SaO2 over 90%

  • Effective in alveolar hypoventilation or V/Q mismatch, but NOT in shunt!

  • Non-Invasive Ventilation (NIV)(CPAP or BiPAP) or Ventilator

• Positioning for optimal oxygenation – HOB up and good lung down

• Pulmonary exercises:

  • Deep breath - hold for 3 sec - at least 10x/hour (IS)

  • No dry coughing

• Secretions:

  • Hydrate (movement)

  • Suction

• Planning for activity/recovery/rest

• Don't forget nutritional support

• Medications: bronchodilators, steroids, sedation, neuromuscular blockade, analgesia

aspiration

• Acid:

  • Bronchospasm & atelectasis

  • Inflammatory response with severe hypoxemia 2o V/Q mismatch and shunt

  • Frequently progresses into ARDS

• High ph Gastric – bacterial pneumonia

• Nonacid Food:

  • Edema & hemorrhage, then foreign body response

  • Hypoventilation

• Patients with aspiration are at HIGH RISK of developing ARDS

acute respiratory distress syndrome (ARDS)

• Inflammatory syndrome marked by:

  • Disruption of alveolar capillary membrane

  • Noncardiogenic pulmonary edema

  • May develop from direct injury to pulmonary epithelium or secondary to nonpulmonary insult stimulating mediator release

• Major risk factors: sepsis, aspiration, diffuse pneumonia, trauma

• V/Q mismatch, alveolar deadspace, alveolar hypoventilation, and shunt → severe refractory hypoxemia

• Suspect ARDS with persistent hypoxemia despite supplemental oxygen

management of ARDS

• Most effective treatment is supportive care

• Ventilator:

  • Low volume (4-6 ml/kg) with permissive hypercapnia (up to pCO 2 80)

  • Maintain plateau pressures less than 30 cm

  • Variety of ventilator modes/settings

  • Inverse ratio ventilation (IRV)

  • PEEP & other maneuvers to achieve alveolar recruitment

• Proning: at least 16 hours a day

• Neuromuscular blockade for 24-48 hours, if needed

• Maintain pH 7.20 or higher

• Maintain C.O.

  • But keep dry (adequate but low end of preload)

outcomes of ARDS

• Mortality = 40%

• Pulmonary fibrosis

• Potential for permanent neurologic impairment with impaired quality of life

• Post-ICU syndrome

• Use therapeutic communication, the nurse would discuss: recovery will take time and there will be some residual pulmonary damage

alveolar hypoventilation

• Respiratory Failure due to Alveolar Hypoventilation is Respiratory Acidosis with Hypoxemia

• Same causes and management of respiratory acidosis

• Pulmonary embolus (dead space)

V/Q mistmatch

• Ventilation/perfusion:

  • Zone 1 best lung sounds

  • If all is healthy, the net result is an equal ventilation/perfusion ratio

  • Atelectasis, pneumonia, pulmonary edema, ARDS

  • V/Q mismatch still responsive to O2 (O2 effectively treats hypoxemia)

  • Weight of the heart and diaphragm compress the dependent alveoli

  • Secretions and edema pool in posterior region of the lungs where perfusion tends to be higher

shunt

• Intrapulmonary shunting causes respiratory failure

• Needs positive pressure

• IS helps pop open alveoli in zone 3 that don’t get good ventilation

high flow nasal cannula

• Heated & Humidified O2:

  • ↓ airway inflammation

  • Maintain mucociliary function

  • ↑ mucous clearance

  • Reduce caloric expenditure

• High flow rates:

  • Increase FiO2

  • Decrease deadspace

  • Provide low level positive pressure (PEEP)

  • ↓ work of breathing

• Benefits:

  • Reduced need for intubation

  • Decreased work of breathing

  • Providing a low level of positive pressure

proning

• Traditionally used in ARDS patients on mechanical ventilator

• Early use in non-ventilated patients with hypoxemia due to COVID-19 has delayed and reduced needs for intubation

• Good lung down - less damaged areas of lung are now matched with highest perfusion – improved V/Q matching

• Reduces alveolar compression by the heart & diaphragm - allowing better expansion of the dorsal lung--more surface area = alveolar recruitment

• Proning → improved oxygenation

management of aspiration

• Goal is SUPPORTIVE!

• O2 Therapy:

  • NIV & Mechanical Ventilation if necessary

• Nursing as previously described

  • Possible bronch (no lavage)

• Drugs:

  • No steroids

  • Antibiotics after 48 hours

• Most important intervention: prevent it!!

prevention of aspiration

• Maintain HOB 30-45 degrees

• Use sedatives as sparingly as feasible

• Maintains ET cuff pressures at an appropriate level, and ensure that secretions are cleared from above the cuff before it is deflated