2210 Unit 4

Two approaches to mechanical ventilation and ARDS

1. Open lung approach--PCV, focus on maintaining low Pplat while monitoring Vt, uses recruitment techniques with high levels of PEEP. 2. ARDS net approach--VCV, focus on maintaining low Vt while monitoring Pplat, PEEP set based upon FiO2 requirement.

Dry drowning

10-15% of deaths are due to laryngospasm/airway obstruction with no aspiration.

Shock

A clinical condition caused by any process which produces an acute decrease in cardiac output.

Hypoxemic-hypercapnic respiratory failure

A low PaO2, an increased PaCO2 and an increased A-a. Severity of hypoxemia is out of proportion to the CO2 retention resulting from hypoventilation. Inadequate avelolar ventilation and impaired oxygen transport.

Tension pneumothorax

A medical emergency! Life threatening and requires immediate treatment. Spontaneous or traumatic, open or closed. "One way valve mechanism". Air enters pleura on inspiration, hole in pleura closes on expiration and air is trapped in pleural space. Pleural pressure becomes positive, mediastinal shift to unaffected side, decreased Qt and BP, tachycardia, tachypnea, hypoxemia, severe respiratory distress.

Non-cardiogenic pulmonary edema

A type of lung congestion that occurs in the absence of cardiac malfunction. In contrast to cardiac pulmonary edema, the findings of heart failure are absent. The exact cause of the various types of non-cardiac pulmonary edema is speculative. Disruption of the endothelial lining of pulmonary capillaries vs. increased intravascular pressure from thrombi or venous constriction. Regardless of cause, outcome is the same--imparied gas exchange and hypoxemia.

With a closed pneumothorax: A. Air enters the pleural space B. Air enters the pleural space through the parietal pleura. C. The pressure in the pleural space is positive. D. There is direct contact between the pleural space and the atmosphere.

A. Air enters the pleural space.

When a pneumothorax occurs: I. Atelectasis and hypoxemia may occur. II. The lung tends to collapse. III. The chest wall tends to collapse. IV. There may be a resulting fall in cardiac output. A. I, II, IV B. I, II, III C. III, IV D. I, II, III, IV

A. Atelectasis and hypoxemia may occur, the lung tends to collapse, there may be a resulting fall in cardiac output.

All of the following statements are true regarding the pharmacologic management of ARDS except one. Which statement is not true? A. Corticosteroids are indicated in established cases B. Vasopressors may be indicated for low blood pressure C. Antibiotics are indicated for infection D. Diuretics may be used to prevent pulmonary edema

A. Corticosteroids are indicated in established cases

With an open pneumothorax there is: I. No trauma involved. II. Direct contact with the atmosphere. III. A mediastinal shift. IV. No possibility of a tension pneumothorax. A. II, III B. I, IV C. III D. I, II, III, IV

A. Direct contact with the atmosphere and a mediastinal shift.

Physical findings seen with ARDS include: I. Increased minute ventilation II. Tympanic percussion note III. Severe dyspnea IV. Decreased tactile fremitus A. I, III B. III, IV C. I, III, IV D. I, II, III, IV

A. Increased minute ventilation and severe dyspnea.

A spontaneous pneumothorax: A. Occurs without evidence of trauma. B. Occurs spontaneously as a result of trauma. C. Always occurs in a previously healthy individiual. D. Occurs as a result of a tear in the parietal pleura.

A. Occurs without evidence of trauma.

True statements regarding the management of a pneumothorax include: I. Oxygen therapy is required for related hypoxemia II. Chest tube drainage is required for all cases of pneumothorax. III. Insertion of a large bore needle into the pleural space may be required in emergencies. Iv. Chest tube drainage with gentle suction may be required in some cases. A. I, III, IV B. I, III C. I, II D. I, II, III, IV

A. Oxygen therapy is required for related hypoxemia, insertion of a large bore needle into the pleural space may be required in emergencies, chest tube drainage with gentle suction may be required in some cases.

The following is true concerning flail chest: I. Pendelluft may occur II. Double fracture of three or more ribs is present III. Increased lung compliance may develop IV. Paradoxical movement of the chest may occur. A. I, II, IV B. II, IV C. II, III, IV D. I, II, III, IV

A. Pendelluft may occur, double fracture of three or more ribs is present, paradoxical movement of the chest may occur.

Signs and symptoms of a hemothorax include: I. Hyperresonant percussion note on the affected side II. Mediastinal shift toward the affected side III. Tachypnea and tachycardia IV. Increased breath sounds on the affected side A. III B. II, III C. I, II, III D. I, II, III, IV

A. Tachypnea and tachycardia

Lab method for confirming respiratory failure

ABG

Ventilator-induced lung injury

ARDS is one of the most likely pathologies to lead to ventilator-induced lung injury because of high impedance to ventilation and heterogenous nature. Increased levels of shunting and deadspace make doctors and therapists want to ventilate at high pressures, which increases the probability of lung injury.

Other causes of ARDS

Acute paraquat poisoning, anaphylaxis, aspiration of gastric contents, central nervous system disease, cardiopulmonary bypass, congestive heart failure, disseminated intravascular coagulation, drug overdose, extensive burn, emboli, fluid overload, head injury, inhalation of toxic fumes or gases, immunologic reaction, massive transfusion of stored blood, multiple fractures, near drowning, neurogenic pulmonary edema, nonthoracic trauma, oxygen toxicity, pulmonary contusion, pancreatitis, radiation induced lung injury, sepsis syndrome, thoracic trauma, uremia.

Pneumothorax should be suspected in what situations?

Acute respiratory distress, difficulty ventilating and deteriorating blood gases in patients receiving positive pressure ventilation, sudden dyspnea following certain diagnostic and therapeutic procedures, acute dyspnea following an industrial or motor vehicle accident, sudden dyspnea and chest pain in a previously healthy young male, worsening of dyspnea in a patient with tuberculosis or emphysema.

Pathophysiology of a pneumothorax

Air accumulates in the pleural space and visceral and parietal pleura separate. Lung tends to collapse due to its' elasticity and chest wall tends to spring out due to its' natural tendency to expand. Leads to decreased ventilation of the collapsed lung and increased ventilation of the unaffected lung, atelectasis and hypoxemia.

Chest tubes

Allow the removal of air or fluid while preventing reentry to the pleural space.

Lung contusion

Almost always present with flail chest, most common parenchymal injury due to blunt chest trauma. Results from the accumulation of edema fluid and blood in the alveoli and interstitium. This can lead to decreased lung compliance, inflammation, atelectasis and hypoxemia, can be clinically similar to ARDS, but localized.

Pulmonary causes of hypercapnic respiratory failure

Alveolar hypoventilation

Four pulmonary causes of hypoxemia

Alveolar hypoventilation, diffusion defects, right to left shunt, ventilation-perfusion mismatch.

Acute superimposed on chronic respiratory failure

An acute deterioration of blood gases seen in individuals with pre-existing hypoxemia and/or hypercapnia (ie COPD).

Indications for mechanical ventilation with respiratory failure

Apnea, hypercapnic failure, impending hypercapnic failure, hypoxemic failure. Decision should be made carefully and criteria are variable from patient to patient. Patients with acute (reversible) RF are more suitable candidates. Many patients with acute superimposed on chronic RF can be successfully managed without mechanical ventilation. Mechanical ventilation is not curative.

Clinical features of respiratory failure

As variable as the number of disorders that can cause respiratory failure. Depends on underlying diseasee, precipitating factors and the effects of hypoxemia and hypercapnia.

Tracheobronchial injuries

Associated with severe chest trauma, may be blunt or penetrating. Commonly occur near origin of mainstem bronchi and may consist of small lacerations and partial or complete fractures, with or without separation.

Chest trauma is: I. A common cause of death and disability. II. The most common cause of death. III. Responsible for over 100,000 deaths a year. A. I B. I, III C. II, III D. I, II, III

B. A common cause of death and disability responsible for over 100,000 deaths a year.

True or False: ARDS is characterized by all of the following findings except one. Which finding is not typical with ARDS? A. Rapidly progressive dyspnea B. Bradypnea C. Refractory hypoxemia D. Decreasing compliance

B. Bradypnea

Common signs and symptoms of a lacerated trachea include all of the following except one. Which of the following is not a common sign or symptom? A. Respiratory distress B. Hemoptysis C. Atelectasis D. Subcutaneous emphysema

B. Hemoptysis

Common causes of ARDS include: I. Infection II. Trauma III. Shock A. I B. I, II, III C. II D. II, III

B. Infection, trauma and shock

Signs and symptoms of flail chest may include all of the following except one. Which sign or symptom is not present? A. Decreased lung volumes B. Respiratory alkalosis and hyperoxemia C. Respiratory acidosis and hypoxemia D. Decreased lung compliance

B. Respiratory alkalosis and hyperoxemia

Recommendations for the initial ventilator settings for patients with chest trauma include: I. Starting with an FiO2 of 0.40 to 0.60 or greater II. Setting PEEP initially at 5 to 15 cwp III. Starting with an FiO2 of 1.0 IV. Setting PEEP initially at 0 to 5 cwp A. I, II B. III, IV C. II, III D. I, IV

B. Starting with an FiO2 of 1.0 and setting PEEP initially at 0 to 5 cwp

Manging combined respiratory failure

Because primarily seen in patients with COPD, administer oxygen with caution. PPV should be avoided if at all possible. When it is required, consider that complications are more frequent, need is usually prolonged, weaning is difficult, the goal is to get back to the PATIENT'S normal ABG.

Where should the chest tube drainage system always be kept?

Below the level of the patient's chest.

Cardiac tamponade

Blood or fluid in the pericardial sac. Can be due to blunt or penetrating injuries. (Rarely occurs with non-penetrating). Suspected when there is chest trauma to the region of the heart. Causes increased intra-pericardial pressure, decreased venous return and decreased cardiac output.

Two categories of chest trauma

Blunt and penetrating

Smoke inhalation pulmonary edema

By direct damage to the a/c membrane. Effects may be immediate or delayed. Observe patient for 12-24 hours. Treatment - corticosteroids prophylactically.

An iatrogenic pneumothorax is: A. Commonly caused by motor vehicle accidents. B. Usually a result of ruptured blebs on the surface of the lung. C. A result of complications of various procedures performed on the patient. D. Common in healthy young males.

C. A result of complications of various procedures performed on the patient.

Physical exam of the patient with a tension pneumothorax may reveal: A. Rales and ronchi B. Dull percussion note C. Displaced heart sounds D. Bradycardia

C. Displaced heart sounds

All of the following statements regarding fluid balance in patients with ARDS are true except one. Which statement is not true? A. Hypovolemia can lead to decreased cardiac output. B. Overhydration can lead to pulmonary edema C. Diuretics may be used to enhance fluid movement from the alveoli to the pulmonary capillary. D. The goal of fluid therapy is to maintain a level of fluid that will prevent pulmonary edema while maintaining cardiac output.

C. Diuretics may be used to enhance fluid movement from the alveoli to the pulmonary capillary.

Chest x-ray findings with a pneumothorax may include all of the following except one. Which finding is NOT typical with pneumothorax? A. A visible line of the pleura B. Increased density of the collapsed lung C. Increased bronchovascular markings D. Mediastinal shift

C. Increased bronchovascular markings

Signs and symptoms of a ruptured diaphragm include all of the following except one. Which of the following signs or symptoms are not typical? A. Cough and dyspnea B. Bowel sounds present in the chest C. Increased thoracic movement D. Paradoxical abdominal movement

C. Increased thoracic movement

Pulmonary function findings in ARDS reveal all of the following except one. Which of the following is not a typical finding? A. Decreased lung compliance B. Tachypnea C. Increased volumes and capacities D. Decreasing diffusing capacity

C. Increased volumes and capacities

Pathophysiologic changes seen with ARDS include: A. A cardiogenic pulmonary edema B. Increased lung compliance C. Perfusion in excess of ventilation D. Decreased pulmonary vascular resistance (PVR)

C. Perfusion in excess of ventilation (shunt)

The most common type of chest wall injury is: A. Flail chest B. Pneumothorax C. Rib fracture D. Lung contusion

C. Rib fracture

Cardiac tamponade may lead to: A. Hypertension B. Decreased pulmonary capillary wedge pressure C. Widened mediastinum on chest x-ray D. Decreased central venous pressure

C. Widened mediastinum on chest x-ray

Diagnosis and treatment of blunt injuries to the larynx

CT or bronchoscopy. Treated with tracheostomy and/or surgical repair.

Determining the cause of hypoxemia mathematically

Calculate the sum of PO2 + PCO2 110-130 mmHg on RA = hypoventilation (hypercapnic RF) <110 on RA or O2 = V/Q mismatch, diffusion defect or shunt (hypoxemic RF) >130 = patient was breathing O2 or if the report indicates the patient was breathing room air, there was an error made.

Removal of chest tube

Can be removed when air or fluid are no longer present. X-ray evidence of resolution of the initial problem should be made before removal. Fail of water to oscillate or lack of bubbling indicate that fluid or air are no longer draining. Place patient on their side, remove dressing, remove sutures, instruct patient to inspire maximally and perform valsalva maneuver, secure the dressing with adhesive tape.

Vascular injuries

Can cause significant hypotension and the need for surgical repair. Patients typically have multiple chest trauma and require mechanical ventilation.

Hemodynamic findings with CHF (cardiogenic)

Cardiac enlargement, LV gallup, engorged neck veins. Increased Ppa, increased Pcwp (>18), decreased Qt, increased CaO2-CvO2, normal CVP

Four major categories of shock

Cardiogenic, hematogenic, neurogenic, vasogenic. All lead to acute decrease in cardiac output.

Management of drowning/near drowning

Care is aimed at improving V/Q and increasing the FRC (PPV with PEEP or CPAP). Aerosol epinephrine for bronchospasm, aerosol alcohol for pulmonary edema (uncommon), restore fluid and electrolyte balance and acid/base balance, antibiotics for infection, digitalis/diuretics with pulmonary edema, monitoring.

Near drowning pulmonary edema

Caused by aspiration and may be immediate or delayed. Altered a/c permeability. Signs and symptoms include SOB, non-pleuritic chest pain, cough, fine course rales, cyanosis, hypoxemia, no signs of heart failure. X-ray shows fluffy alveolar infiltrates with normal cardiac shadow and size, no Kerley B lines.

Toxic gas inhalation pulmonary edema

Caused by chlorine, nitrogen, oxides, sulfur oxides, ozone, phosgene, paraquat by direct damage to the a/c membrane. Effects may be immediate or delayed. Observe for 12-24 hours.

Hematogenic shock

Caused by hemorrhage, burns, severe dehydration. Decreased blood volume leads to decreased venous return and decreased cardiac output.

Vasogenic shock

Caused by infection. Relaxation of smooth muscles of vessel walls leads to widespread vasodilation and peripheral pooling of blood in viscera, which leads to decreased venous return and decreased cardiac output.

Aspiration pulmonary edema

Caused by inhaling gastric contents, especially HCl. May lead to severe pulmonary edema. Physical damage to the a/c membrane.

Cardiogenic shock

Caused by myocardial diseases. Decreased cardiac emptying leads to decreased cardiac output.

Neurogenic shock

Caused by pain, medicines, syncope. Loss of sympathetic tone of blood vessels leads to widespread vasodilation and peripheral pooling of blood in viscera, which leads to decreased venous return and decreased cardiac output.

Uremic pulmonary edema

Caused by renal failure, increased capillary permeability due to circulating toxic substances. Treatment is dialysis.

Neurogenic pulmonary edema

Caused by severe head trauma, seizures, intracranial hemorrhage or profound infection. Suspect - increased sympathetic discharge leads to pulmonary venous hypertension or shift of systemic blood volume to the pulmonary circulation.

Decompensatory phase of shock

Characterized by hypotension. If cerebral blood flow becomes low enough, the patient may become lethargic and/or comatose. Widespread anoxia may make recovery impossible and death occurs (irreversible shock).

Idiopathic spontaneous pneumothorax

Common in young males, 18-40 y/o, tall and thin with long narrow chest (weakened lung apex due to gravity). Rupture of apical cysts or blebs may also be the cause.

Flail chest

Commonly caused by crushing injuries. Double fractures of three or more adjacent ribs, frequently complicated by contusion of the lung. Paradoxical chest movement. Instability leads to increased work of breathing, hypoventilation due to pain, hypoxemia, hypercapnia, ineffective cough, accumulation of secretions. Pendelluft may also occur.

Aortic rupture

Commonly due to motor vehicle accidents, 80% are DAS due to massive blood loss. Most important diagnostic sign is widening of mediastinum on chest x-ray. Key to diagnosis is aortic angiography (if they survive the original injury, will be in profound shock). Treatment is transfusion and surgical repair.

Iatrogenic pneumothorax

Complications of various procedures including positive pressure ventilation, thoracentesis, pleural biopsy, lung biopsy, puncture of the subclavian vein, tracheostomy, chest or neck surgery.

Bubbling in the suction bottle

Continuous bubbling should be apparent in the suction control bottle. This indicates suction is working.

Possible effects of severe hypoxemia

Cyanosis, confusion, anaerobic metabolism (lactic acidosis), coma, death

Oxygen delivery to the tissues depends on: I. cardiac output II. PaO2 III. SaO2 IV. Hemoglobin A. I, II B. I, III C. II, III, IV D. I, II, III, IV

D. Cardiac output, PaO2, SaO2 and hemoglobin

A traumatic pneumothorax: I. May be caused by a tear in the parietal pleura. II. May be caused by a tear in the visceral pleura. III. May lead to a tension pneumothorax. IV. May be iatrogenic. A. II, III B. I, III, IV C. I, III D. I, II, III, IV

D. May be caused by a tear in the parietal or visceral pleura, may lead to a tension pneumothorax and may be iatrogenic.

A tension pneumothorax: I. May be open or closed. II. May be spontaneous or traumatic. III. May be iatrogenic. IV. Is a medical emergency. A. IV B. I, II, IV C. II D. I, II, III, IV

D. May be open or closed, may be spontaneous or traumatic, may be iatrogenic, is a medical emergency.

Complications of rib fractures include: I. Pneumothorax II. Atelectasis III. Hemothorax IV. Fail chest A. I, III B. IV C. I, III, IV D. I, II, III, IV

D. Pneumothorax, atelectasis, hemothorax and flail chest

A pneumothorax should be suspected in the following situations: I. Sudden dyspnea following an industrial accident. II. Deteriorating blood gases in a patient being mechanically ventilated. III. Increased dyspnea in a patient with COPD. IV. Sudden dyspnea following a thoracentesis. A. I, II, IV B. I, IV C. II, III D. I, II, III, IV

D. Sudden dyspnea following an industrial accident, deteriorating blood gases in a patient being mechanically ventilated, increased dyspnea in a patient with COPD, sudden dyspnea following a thoracentesis.

Pathologic changes seen with ARDS include: I. Surfactant depletion II. Hyaline membrane formation III. Leaky pulmonary capillaries IV. Hemorrhage A. III B. I, II C. I, II, III D. I, II, III, IV

D. Surfactant depletion (secondary problem), hyaline membrane formation, leaky pulmonary capillaries (primary problem), hemorrhage

Secondary drowning

Death from delayed complications following apparent recovery.

Alveolar hypoventilation

Decreased minute ventilation, increased PaCO2. CO2 displaces PAO2, leading to decreased PaO2. A-a is normal.

Treatment of a hemothorax

Depends on size. Observation for small, thoracentesis for moderate, chest tube drainage for large. Surgical repair with uncontrolled bleeding.

Managing shunt

Depends on the type of shunt. Anatomic shunt - surgical repair. Physiologic shunt - reopening of the alveoli with PPV (PEEP). Only condition in which 100% oxygen will not bring the PaO2 back up to maximal levels.

Chronic respiratory failure

Develops more slowly, allowing time for the body to at least partially compensate for the underlying disturbances.

Adult respiratory distress syndrome

Difficult to define because is not really a disease, but a clinical syndrome with several common components. Distinct type of respiratory failure with diffuse damage to the a/c membrane, tachypnea, rapidly progressive dyspnea, refractory hypoxemia, diffuse pulmonary infiltration, reduced lung volumes and decreased lung compliance. Typically follows an acute lung injury in a previously healthy individual.

Pulmonary causes of hypoxemic respiratory failure

Diffusion defects, shunt, V/Q mismatch

Things that may lead to respiratory failure

Disorders of the CNS, PNS, respiratory muscles and neuromuscular junction, chest wall and pleura and upper airway or intrinsic lung disease.

Clinical features of ARDS

Dramatically increased minute ventilation, severe progressive dyspnea, increased work of breathing, grunting respirations, cyanosis, intercostal and substernal retractions, cough (all with onset 24-48 hours after initial injury or illness). Breath sounds may be normal early on, progressing to inspiratory crackles and/or bronchial breath sounds. Dull percussion note, increased vocal and tactile fremitus. Tachypnea and tachycardia. Findings are often surprisingly minimal despite a very ill appearing patient. Sputum production varies, but frothy blood-tinged sputum is common. Decreased volumes and capacities, decreased compliance, DLCO decreased.

Clinical features of a pneumothorax

Dyspnea and chest pain, with dyspnea more severe at onset than hours later. Depends on size and type.

Signs and symptoms of diaphragmatic injury

Dyspnea, cough, palpitation, decreased thoracic movement, dull percussion note, decreased breath sounds, presence of bowel sounds in the chest, respiratory distress, nausea and vomiting, abdominal distension, paradoxic movement of the upper quadrant of the abdomen, x-ray evidence of air containing bowel within the chest.

Signs and symptoms of blunt injury to the larynx

Dyspnea, hoarseness, change in voice, hemoptysis, dysphagia, laryngeal tenderness, tracheal deviation, inspiratory stridor, subcutaneous emphysema.

Possible effects of acute hypoxemia

Dyspnea, impaired judgement, clumsiness, tachypnea, increased work of breathing

Diagnosis of cardiac contusion is based upon...

Electrocardiography, angiography, hemodynamic monitoring, measurement of plasma CPK-MB isoenzyme. (LDH, SGOT and CPK almost always increased with chest trauma despite the cause). EKG may show tachycardia, abnormal p waves, PVCs, changes in QRS, ST segment elevation and/or T wave abnormalities.

Treatment of respiratory failure

Establishing and maintaining an adequate airway, proper oxygenation, correcting any acid-base abnormalities, restoring fluid and electrolyte balance, improving circulatory status, treating the underlying disease, instituting mechanical ventilation, preventing complications.

Normal FEV1, FRC and MVV

FEV1 = 50-60 ml/kg FRC = 80-100% predicted MVV = 120-180 L/min

FEV1, FRC and MVV indicating mechanical ventilation

FEV1 = <10 ml/kg FRC= <50% predicted MVV = <20 or <2 x Ve

True or False: Pressure control ventilation has been proven to be superior to volume control ventilation in improving morbidity and mortality in patients with ARDS.

False

True or False: Typical blood gases in a patient with a recent pneumothorax may reveal hypoxemia and respiratory acidosis.

False-- will reveal hypoxemia and respiratory alkalosis initially. Will reveal hypoxemia and respiratory acidosis in late stages.

True or False: Damage to the upper trachea is more common than damage to the distal trachea and mainstem bronchi.

False.

True or False: Despite numerous advances in critical care, the mortality rate for ARDS remains approximately 90 to 95%

False. Current mortality is 50-70%

True or False: Flail chest with paradoxical chest movement is an absolute indication for positive pressure ventilation.

False. Flail chest rarely needs stabilization with PPV unless other condition indicating otherwise is present.

True or False: When ventilating patients with ARDS using the open lung approach, low tidal volumes of 10-12 ml/kg IBW are used to maintain a peak alveolar pressure of <30 cwp.

False. Focus is on maintaining Pplat <30 cwp while monitoring Vt and keeping 4-8 ml/kg.

True or False: Typical arterial blood gas findings in the early stages of ARDS reveal a respiratory acidosis with severe hypoxemia.

False. In the early stages, the ABG will show respiratory alkalosis with moderate hypoxemia. In late stages, it will show respiratory acidosis with severe (refractory) hypoxemia.

True or False: ARDS is a result of a primary surfactant deficiency.

False. Is a primary result of leaky pulmonary capillaries.

True or False: Permissive hypercapnia is contraindicated in patients with chest trauma.

False. Is indicated in patients who also have increased ICP.

True or False: When ventilating a patient with ARDS due to chest trauma, the initial tidal volume used should be 12-15 ml/kg.

False. It should be kept at 4-6 ml/kg.

True or False: Lateral neck x-rays are the key to diagnosis of blunt injuries to the larynx.

False. Lateral neck x-rays are frequently negative.

True or False: Most causes of ARDS are due to direct injury to the lungs.

False. Lungs may be injured directly (aspiration or inhalation of toxic substances such as gastric acid, oxygen toxicity or smoke inhalation) or indirectly (blood-borne infection, trauma, sepsis). Most cases are to due to indirect causes.

True or False: Mechanical ventilation can usually be avoided in most cases of ARDS if CPAP is used.

False. Mechanical ventilation is almost always required to support the patient while their lungs heal.

True or False: Lung contusion rarely occurs as a result of blunt chest trauma.

False. Most common injury due to blunt chest trauma.

True or False: Moderate to severe cases of flail chest require surgical repair to stabilize the chest wall.

False. Only very severe cases require surgical repair.

True or False: Pressure support is rarely useful during weaning in patients with ARDS

False. Pressure support is helpful and allows patient to control gas delivery better than any other mode. Start at the same pressure used with full ventilation and slowly decrease over time until extubation. May take weeks to wean.

True or False: With either volume or pressure ventilation, the plateau pressure should be kept below 50 cwp when ventilating patients with chest trauma.

False. Should be kept below 30 cwp.

True or False: During the repair phase of ARDS, type I alveolar cells proliferate and eventually mature into type II alveolar cells.

False. Type II alveolar cells will proliferate and mature into type I cells.

Possible effects of chronic hypoxemia

Fatigue, apathy, reduced attention, drowsiness, muscle twitching, polycythemia

Indications for mechanical ventilation in patients with chest trauma

Flail chest with paradoxical chest movement, tachypnea, hypoxemia and hypercarbia (respiratory failure), pulmonary contusion with tachypnea and severe hypoxemia while breathing 100% O2, rib fractures with chest pain requiring large doses of respiratory depressant pain control, postoperative thoracotomy, hemodynamic instability (particularly with marginal respiratory reserve), severe associated injuries (ie head trauma).

Blunt chest trauma

Fractures, pulmonary contusion, tracheobronchial injury, myocardial and vascular injury, esophageal perforation, diaphragmatic injury

Three most common causes of shock

Hemorrhage, myocardial infarction and infections.

Radiographic findings with pneumothorax

Hyperlucency in the affected area, visible line of the pleura present, increased density of the collapsed lung, mediastinal shift with a tension, complete collapse of the lung with a tension. Radiographic studies are key to diagnosis! Full expiratory film helps.

Most common ABG findings in near drowning/drowning

Hypoxemia and metabolic acidosis, despite type of water aspirated.

Salt water drowning

Hypoxemia is worse with salt water aspiration. May lead to hypovolemia as fluid rushes into the alveoli from the capillaries.

Acute respiratory failure

Hypoxemia, hypercapnia or both develop so rapidly that the body's compensatory mechanisms are unable to prevent serious consequences. A life-threatening emergency.

Two types of respiratory failure

Hypoxemic respiratory failure and hypercapnic respiratory failure (or a combination of the two).

When to clamp the chest tube

If an air leak is suspected (to determine the source of the leak), when changing drainage bottles. Clamping or obstruction may result in a tension pneumothorax, use with caution!!!

Signs and symptoms of lung contusion

If extensive, cough, dyspnea, hemoptysis, rales and cyanosis. Symptoms intensify during the first 24-72 hours severe cases may progress to ARDS.

Treatment of laceration of the trachea and bronchi

If small and no pneumothorax, they may heal spontaneously. Large air leaks and pneumothorax require surgical repair. Patients may require mechanical ventilation after thoracotomy, especially if other injuries that compromise pulmonary function are present.

Two-bottle chest tube system

If the patient has a significant air leak, a second bottle may be applied as controlled suction. One short tube in the suction control bottle is connected to the water-seal bottle via rubber tubing. A third long tube is submerged 10-20 cm below the surface of water and open to atmosphere at the top. This type of system prevents fluid accumulation in the water seal and the resulting increase in intrapleural pressure required to break the water seal and allow drainage. Continuous bubbling should be apparent in the suction control bottle.

Hypoxemic respiratory failure

Impairment of oxygen transport. A low PaO2 and a PaCO2 that is either normal or low. All known causes of hypoxemia except hypoventilation and a low FiO2 may produce hypoxemic failure. Increased A-a. Usually caused by ALI.

Insertion point of chest tube for fluid

In the sixth or seventh interspace at the midaxillary or posterior axillary line, directed posteriorly.

Insertion point of chest tube for air

In the third or fourth interspace at the midclavicular line, directed toward the apex.

Hypercapnic respiratory failure

Inadequate alveolar ventilation leading to an elevated PaCO2 and low PaO2 (hypoxemia is secondary to hypoventilation and is proportional to the displacement of O2 in the alveoli by CO2. Normal A-a. Causes include anything that leads to hypoventilation.

Signs and symptoms of laceration of the trachea and bronchi

Include severe respiratory distress, pneumothorax/pneumo-mediastinum, subcutaneous emphysema. A large pneumothorax that persists despite chest tube treatment is indicative of a ruptured trachea/bronchi. High mortality rate with complete transection.

Three-bottle chest tube system

Includes a drainage bottle, water seal bottle and suction control bottle. The drainage bottle allows measurement and observation of fluid drained from the pleural space.

Indications for mechanical ventilation in ARDS

Increased work of breathing, oxygenation impairment, impending ventilatory failure, acute ventilatory failure.

Treatment of diaphragmatic injury

Insertion of a nasogastric tube with suction. In cases of ventilatory failure, intubation and mechanical ventilation. Surgical repair.

Compensatory phase of shock

Involves a decreased cardiac output but adequate compensatory mechanisms to maintain blood pressure, such as increased heart rate and arterial vasoconstriction. Also produces cold and clammy skin, pallor and oliguria. In some cases, compensatory arterial vasoconstriction affects the kidneys severely, leading to acute renal necrosis and renal failure. Recovery is possible, but about 1/2 of such cases are fatal.

Pathophysiology of ARDS

Leaky alveolar-capillary membrane--intravascular fluid leaks from the pulmonary capillaries into the alveoli causing non-cardiogenic pulmonary edema and surfactant dilution. Type II cell damage decreases surfactant production, leading to alveolar collapse. The lungs become stiff and volumes are decreased as the lung becomes almost airless. Work of breathing increases. Alveolar flooding and atelectasis lead to shunting and ventilation/perfusion mismatch. Severe hypoxemia develops (refractory), which leads to a dramatic increase in minute ventilation and increased PVR. Increased PVR leads to increased work of right ventricle and possible cor pulmonale.

Penetrating chest trauma

Lung injury, heart injury, vasculature injury, combinations of the three. Almost always requires surgical repair, immediately life threatening when associated with tension pneumothorax and/or significant blood loss. Mechanical ventilation is frequently required following extensive surgical repair.

Treatment of flail chest

Maintaining an open airway, supplemental oxygen, analgesics or intercostal nerve blocks for pain, bronchial hygiene, control of infection, treatment of pulmonary congestion, evacuation of air or fluid from the pleural space. Past treatment included internal stabilization using PPV and PEEP. Mechanical ventilation is now only considered required if one of the following conditions is present: shock, closed head injury, need for immediate surgery, severe pulmonary dysfunction, deteriorating respiratory status. PPV should last about 7-10 days.

Intrinsic lung disease respiratory failure

May be caused by chronic bronchitis, emphysema, asthma, cystic fibrosis, bronchiolitis, adult respiratory distress syndrome, severe pneumonia, interstitial lung disease, pulmonary emboli, oxygen toxicity, pulmonary edema. Most commonly combined respiratory failure or hypoxemic respiratory failure. Acute or chronic.

CNS respiratory failure

May be caused by drug overdose, head trauma, central sleep apnea, primary alveolar hypoventilation, cerebrovascular accident/stroke, tumors, infection, cerebral hypoxia. Hypercapnic with hypoxemia secondary. Acute or chronic.

Muscles and neuromuscular junction respiratory failure

May be caused by myasthenia gravis, muscular dystrophy, polymyositis, botulism, muscle fatigue and atrophy, muscle-paralyzing drugs, hypokalemia and hypophosphatemia. Hypercapnic with hypoxemia secondary. Acute or chronic.

Upper airway respiratory failure

May be caused by obstructive sleep apnea, epiglottitis, laryngotracheitis, trauma, foreign bodies, compressing tumors, tracheal stenosis, congenital deformities. Both types of respiratory failure are possible. Acute or chronic.

Chest wall and pleura respiratory failure

May be caused by pneumothorax, pleural effusion, fibrothorax, kyphoscoliosis, flail chest, massive obesity, rheumatoid spondylitis. Both types of respiratory failure are possible.

PNS respiratory failure

May be caused by poliomyelitis, Guillain-Barre syndrome, ALS, tetanus, spinal cord trauma, MS. Hypercapnic with hypoxemia secondary. Acute or chronic.

Drug overdose pulmonary edema

May be due to IV overload, increased a/c permeability due to severe hypoxemia, aspiration of gastric contents and/or neurogenic effect on vessels. Common after narcotic overdose (heroin and other narcotics, salicylates). Treatment - adequate oxygenation, reversing effects of the causative agent (ie Nalorphine to reverse affects of narcotics).

Blunt injuries to the larynx

May lead to gradually developing obstruction due to edema or sudden obstruction due to crushing.

Fresh water drowning

May lead to hypervolemia as fresh water in the alveoli crosses the a/c membrane into the capillaries. More likely to wash away surfactant.

Monitoring ARDS

May use pulmonary artery catheter (only if ventricular dysfunction is present), CVP (to assess fluid status), daily chest x-rays, pulse oximetry, periodic blood gases, prevent auto-PEEP, use best FiO2, PEEP, Pplat and Paw for best gas exchange.

Treatment for lung contusion

Mild to moderate forms may not require intubation, may only need supplemental oxygen and monitoring. Hypoxemia can be treated with oxygen and mask CPAP.

Stage 1 of ARDS

Minimal findings despite pathology.

Initial ventilator settings for chest trauma

Mode = A/C (CMV) Rate = 10-20 bpm Volume/pressure target = 6-8 ml/kg (4-6 ml/kg with ARDS with a rate of 20-35 bpm) and Pplat < 30 cwp I-time = 1 second PEEP = 5 cwp (none with severe air leaks) FiO2 = 1.0 Flow waveform = decelerating

Ventilation-perfusion mismatch

Most common cause of hypoxemia. A-a is increased.

Closed pneumothorax

Most common. Opening in pleura typically closes, usually no further air entry. Pleural pressure is negative. No contact between pleura and atmosphere. Spontaneous or traumatic, tension possible.

Myocardial injuries

Most commonly myocardial contusion. Can cause arrhythmias, but rarely causes cardiac failure. Mechanical ventilation is rarely needed unless other injuries are present.

Hemodynamic findings with ARDS (non-cardiogenic)

No cardiac enlargement, no LV gallup, no engorged neck veins, Pcwp < 18. Increased Ppa, normal Pcwp, normal Qt, normal CaO2-CvO2, normal CVP.

Management of pneumothorax

No special treatment for a small pneumothorax (15% of lung volume). With no symptoms, the pneumothorax usually reabsorbs in days to weeks. Chest tube drainage for a symptomatic pneumothorax. A tension pneumothorax is a medical emergency and must be treated immediately (can use large bore needle in the third interspace). Oxygen therapy for hypoxemia.

How long does it take for irreversible brain damage to occur with drowning?

Not clear. 3-5 minutes is average, but 10-22 minutes have been reported. (22 minute incident was in ice cold water). The younger you are and the colder the water, the better your chances.

Bubbling in the water-seal bottle

Occasional bubbling is normal. (Air is evacuating the pleural space). Persistent bubbling may indicate a leak and lack of bubbling indicates that no air is being removed.

Treatment for an open pneumothorax

Occlusive pressure dressing over the wound.

Stage 2 of ARDS

Occurs 24-48 hours after initial injury. Patchy, diffuse, symmetrical, bilateral interstitial and alveolar infiltrates are the hallmark. Normal heart size, air bronchograms, clear costophrenic and cardiophrenic angles, absence of pleural effusions.

Stage 3 of ARDS

Occurs 7-10 days after the intial injury. Alveolar fluid begins to clear leaving interstitial edema, interstitial emphysema may occur. Fibrosis during the first few months of recovery is striking. Findings may be normal or reveal only milkd abnormalities in those who completely survive.

Spontaneous pneumothorax

Occurs suddenly with no evidence of trauma and not necessarily evidence of disease. Can occur due to rupture of small bleb or cyst on surface of the lung. Closed pneumothorax. Occurs with tuberculosis and emphysema. If in apparently healthy individual, is an idiopathic spontaneous pneumothorax.

Respiratory failure

Occurs when there is a defect in any part of respiratory system (ventilation, external respiration, internal respiration or perfusion). Common to define by low arterial oxygen tension, with or without an abnormally high carbon dioxide tension. (PaO2 < 60 mmHg and/or a PaCO2 > 50 mmHg).

High altitude pulmonary edema

Occurs within 24-36 hours after ascent and affects young, vigorous and healthy individuals. Native dwellers of high altitude may be affected after a visit to low altititude. Extreme cold and vigorous activity seem to be predisposing factors. Speculated that overperfusion to certain areas of the lung leads to rise in hydrostatic pressure. May be alterations in blood coagubility that cause vascular obstruction, PHTN and transudation into extravascular space. Symptoms: SOB, cough, non-pleuritic chest pain, fine rales. X-ray - fluffy alveolar infilatrates. Treatment = get the patient out of high altitude area.

Water level on a one-bottle chest tube system

On inspiration, the water column should rise, on expiration, it should drop. With PPV, oscillation moves in the opposite direction. Bubbling signifies air leakage from the lung.

Drowning

One of the major causes of accidental death at 5,000 cases per year. Third leading cause of accidental death. Most ages 10-19, 85% male. Death from asphyxiation from submersion.

Open pneumothorax

Opening directly into the pleural space. Result of trauma, direct contact with atmosphere. Pleural pressure is atmospheric pressure. Air enters the pleural space on inspiration and mediastinum shifts to unaffected side, on expiration air passes out through opening in parietal pleura and chest wall and mediastinum shifts back to midline. May have a sucking chest wound, pendelluft. May develop into tension pneumothorax.

Normal PaCO2, pH, Vd/Vt and PaO2

PaCO2 = 35-45 mmHg pH = 7.35 - 7.45 Vd/Vt = 0.2-0.4 PaO2 = 80-100 mmHg

PaCO2, pH, Vd/Vt and PaO2 indicating mechanical ventilation

PaCO2 = >50 mmHg pH = <7.25 Vd/Vt = >0.60 PaO2 = <50 mmHg on RA, <60 on O2

Gas exchange and pressure targets for ARDS

PaO2 in ALI > 70 mmHg, in moderate ARDS > 60 mmHg, in severe ARDS >50 mmHg. PaCO2 40 mmHg if possible with permissive hypercapnia to avoid high peak alveolar pressure. PEEP as necessary to maintain alveolar recruitment (10-20 cwp).

Pathology of drowning

Panic - violent struggle to reach the surface Breath holding, leading to hypoxemia and hypercapnia. This triggers the respiratory center and the victim is forced to inhale. The entrance of H2O causes intense laryngospasm.

Signs and symptoms of cardiac tamponade

Paradoxic pulse, hypotension, increased Pcwp, weak pulse, muffled heart sounds, distended neck veins, increased CVP, widened mediastinum on chest x-ray.

Signs and symptoms of flail chest

Paradoxical movement of the chest, decreased lung volumes, decreased lung compliance, respiratory alkalosis and hypoxemia (early), respiratory acidosis and hypoxemia (late), tachycardia and tachypnea.

Managing hypercapnic respiratory failure

Patients with severe respiratory acidosis who do not respond to conservative management and show progressive deterioration or exhaustion should be ventilated. (An elevated PCO2 or a rising PCO2 in someone who was previously hyperventilating, such as asthmatics).

Right to left shunt

Perfusion of blood past non-ventilated alveoli, ie atelectasis. A-a is increased.

Treatment of cardiac tamponade

Pericardiocentesis, transfusion and surgical repair.

Primary objectives in treating drowning

Prompt restoration of ventilation, oxygenation, correction of acidosis. On scene--airway, mouth to mouth, oxygen, cardiac massage. Watch for possible head or neck injury with diving accident. ABG on arrival at hospital. At hospital, airway, intubation, oxygenation and ventilation.

One-bottle chest tube system

Provides drainage by gravity. Chest tubes are connected via flexible tubing to a long glass tube submerged under water in a transparent drainage bottle (this forms a seal that acts like a one-way valve, preventing air from entering the pleural space). Tip of the long tube is submerged about 2 cm below the water surface and a shorter tube acts as a vent for evacuated air.

Clinical manifestions with drowning/near drowning

Pulmonary edema is common due to increased a/c permeability, hypertonic salt solution, severe hypoxemia or dissolved particulate matter in water. Usually unconscious or agitated and confused, cold and cyanotic. Respirations usually absent, otherwise tachypnea. Cough may bring up pink, frothy secretions.

Monitoring the mechanically ventilated patient with chest trauma

Pulseoximetry and ABGs, heart rate and BP, consider pneumothorax and extraalveolar air or pulmonary embolism with any rapid deterioration. Must avoid auto-PEEP. Use just enough pressure for adequate oxygenation. Fluid overload is common following surgery, and can be associated with shunting and decreased compliance. Follow nutritional status.

Normal Qs/Qt, A-a, PaO2/PAO2 and PaO2/FiO2

Qs/Qt = 2-5% A-a = 30-50 mmHg (on 100% O2) PaO2/PAO2 = 0.80 PaO2/FiO2 = 350-450 mmHg

Qs/Qt, A-a, PaO2/PAO2 and PaO2/FiO2 indicating mechanical ventilation

Qs/Qt = >20-30% A-a = >350 mmHg PaO2/PAO2 = < 0.15 PaO2/FiO2 = <200 mmHg

Non-pulmonary causes of hypoxemia

Reduced blood flow to the tissues, anemia, non-functioning hemoglobin, anatomic shunts, anything that decreases cardiac output.

Pathology of ARDS

Regardless of the cause, diffuse alveolar damage with increased permeability of the a/c membrane, inflammation and increased number of neutrophils in the alveoli. Within a few hours after the onset of alveolar inflammation, type I cells swell and become detached from their basement membrane leading to leakage of edema fluid through the a/c membrane. Endothelial cells that line the alveolar capillaries swell and lose their normal barrier function. Fluid movement also causes damage to type II alveolar cells, decreasing their ability to produce surfactant, resulting in atelectasis and shunting. Basement membrane becomes covered with a layer of fibrin and other proteins (hyaline membrane), type II cells being to proliferate and mature into type I cells (repair process). Repair may or may not be successful and fibrosis may occur.

Treatment of fracture

Relief of pain, prevention of atelectasis and pneumonia, analgesics/intercostal nerve block, deep breathing and coughing/SMI

Compensation for hypercapnia

Renal buffering of hydrogen ions to bring pH to normal.

Physical exam findings with pneumothorax

Respiratory distress, dyspnea, cyanosis, restlessness, decreased or absent breath sounds on affected side, hyperresonant percussion note on affected side, tachycardia, tachypnea, displaced heart sounds due to a shift in the mediastinum, mediastinal shift to unaffected side (with tension). Physical exam may be normal with a small pneumothorax.

Traumatic pneumothorax

Result of penetrating wounds to the chest wall (knives, bullets and other sharp objects) or by non-penetrating chest trauma (motor vehicle accidents/broken ribs tearing visceral pleura).

Hemothorax

Ribs may be forced into the pleura or into intercostal arteries, causing bleeding in the pleural space. Signs and symptoms are decreased to absent breath sounds, dull percussion, tachypnea and tachycardia, mediastinal shift to unaffected side. Severity of symptoms depends on the size.

Signs and symptoms of fracture

Severe pain, splinting, rapid shallow breathing, inability to cough effectively, atelectasis and hypoxemia, pneumonia, isolated fractures rarely require mechanical ventilation unless associated with other injuries such as pulmonary contusion.

Cardiac contusion

Should be suspected after blunt injury. May range from minor localized edema to complete myocaridal rupture. Diagnosis is difficult due to arrhythmias, hemodynamic instability and similarity to myocardial infarction.

Fractures may involve...

Sternum, vertebrae, clavicles, scapulae, ribs

Prognosis with ARDS

Survival rate is 50-70%. Patients whose oxygenation status improves early in the course of the disease have a better prognosis, patients with ARDS due to sepsis have a worse prognosis. Survivors usually recover completely.

Possible effects of hypercapnia

Tachycardia, hypertension, headaches, confusion, dizziness, muscle twitching, tremor, mental depression, loss of consciousness, dilation of peripheral and cerebral blood vessels, constriction of pulmonary vessels, increased hydrogen ions/respiratory acidosis.

Possible cardiovascular effects of hypoxemia

Tachycardia, increased cardiac output, arrhythmias, dilation of peripheral and cerebral blood vessels, constriction of pulmonary blood vessels, pulmonary hypertension and cor pulmonale

Compensation for hypoxemia

Tachypnea, tachycardia (acute), polycythemia (chronic).

Pneumothorax

The presence of air the pleural space. May enter through a tear in the visceral pleura (closed) or through a perforation in the chest wall and parietal pleura (open).

Synonyms for ARDS

There should be common clinical findings, pathology and physiologic changes if a situation is to be labeled ARDS. Synonyms fitting under this include: Acute alveolar failure, adult hyaline membrane disease, alveolar capillary leak syndrome, aspiration pneumonia, capillary leak syndrome, congestive atelectasis, DaNang lung, diffuse alveolar damage, hemorrhagic atelectasis, hemorrhagic pulmonary edema, increased permeability pulmonary edema, massive fat embolism, near drowning, noncardiogenic pulmonary edema, oxygen pneumonitis, oxygen toxicity, postnontraumatic pulmonary insufficiency, postperfusion respiratory insufficiency, posttraumatic pulmonary insufficiency, pulmonary edema due to narcotic overdose, pump lung, severe aspiration pneumonia, severe viral pneumonia, shock lung syndrome, smoke inhalation, stiff lung syndrome, wet lung syndrome, white lung syndrome

Diffusion defects

Thickening of the a/c membrane. Hypoxemia is usually mild, easily corrected with small increase in FiO2. A-a is slightly increased.

Does type of water make a difference in drowning?

This is debatable, but on occasion can cause significant problems with water and electrolyte balance (takes a LOT of fluid).

Pleuro-vac

Three-bottle chest tube system in one plastic container.

Length of tubes below water surface

Tip of the long tube in the water seal bottle should be 2 cm below the surface of the water. Long tube in the suction control should be at least 10 cm below the surface of the water.

Treatment of non-cardiogenic pulmonary edema

Treat the cause, adequate oxygenation, management similar to ARDS. If OD with narcotics, give antagonist. If due to increased ICP, lower pressure. If due to high altitudes, give O2 and evacuate to lower altitude.

Management of ARDS

Treatment is primarily supportive and includes treatment of the underlying cause, supplemental oxygen (lowest possible FiO2), fluid management (avoiding overhydration or hypovolemia), pharmacologic intervention (antibiotics, corticosteroids (if given early), diuretics, vasopressors, almitrine) mechanical ventilation, monitoring, weaning from ventilatory support.

Managing hypoxemic respiratory failure

Treatment requires adequate tissue oxygenation. FiO2 rapidly corrects hypoxemia due to V/Q mismatch, diffusion defects and hypoventilation. (NOT shunt) Be careful for oxygen toxicity. Oxygen deliver also depends on adequate cardiac output.

True or False: ARDS is a heterogenous disease with areas of consolidation, areas of collapse that are recruitable, areas of normal tissue, and intrapulmonary bleb formation in some patients.

True

True or False: ARDS progresses through three distinct phases: the first phase is characterized by minimal findings despite pathology, the second phase results in alveolar and endothelial damage, increased vascular permeability and increased lung water and lung protein, and the third phase is characterized by extensive fibrosis.

True

True or False: All of the causes of ARDS lead to an increased permeability of the alveolar-capillary membrane.

True

True or False: Early pathology seen in ARDS includes damage to type I alveolar cells with resulting pulmonary edema.

True

True or False: Emergency treatment of diaphragmatic injury includes the insertion of a nasogastric tube.

True

True or False: Full ventilatory support is recommended initially for ventilating patients with chest trauma.

True

True or False: Ideally patients with ARDS should be allowed to trigger the ventilator during ventilatory support. However, with severe cases, patient-triggered ventilation results in compromised gas exchange and hemodynamics. Pharmacologic support in these patients should be used to prevent patients from "fighting" the ventilator.

True

True or False: In chest trauma patients who develop ARDS, the mechanical ventilation course can be difficult, with prolonged and difficult weaning.

True

True or False: Mechanical ventilation is indicated in ARDS to reverse shunting and severe hypoxemia, reduce the work of breathing and treat acute ventilatory failure.

True

True or False: Most victims of a lacerated aorta are dead at the scene of the accident.

True

True or False: Pneumothorax and subcutaneous emphysema are common complications of mechanical ventilation in patients with chest trauma.

True

True or False: Pneumothorax may occur with or without trauma.

True

True or False: Pulmonary function in a patient with a pneumothorax will reveal decreased volumes and capacities.

True

True or False: Refractory hypoxemia is hypoxemia that does not respond well to oxygen therapy.

True

True or False: Signs and symptoms and treatment of cardiac contusion are similar to the signs and symptoms and treatment of myocardial infarction.

True

True or False: The accumulation of neutrophils in the alveolar fluid is a common finding in ARDS.

True

True or False: The following hemodynamic findings are representative of ARDS: Pcwp = normal Qt = normal Ppa = increased Heart size = normal

True

True or False: The most common symptoms of a pneumothorax are dyspnea and chest pain.

True

True or False: There are many different ways to classify a pneumothorax.

True

True or False: Treatment of a small hemothorax may require nothing more than close observation.

True

True or False: When ventilating patients with ARDS due to chest trauma, long inspiratory times may help increase mean airway pressure and improve oxygenation.

True

True or False: With ARDS a peak alveolar pressure of <30 cwp and PEEP that maintains alveolar recruitment (>10-20 cwp) helps to minimize the risk of ventilator-induced lung injury.

True

True or False: With ARDS, the movement of fluid across the alveolar-capillary membrane causes damage to the type II alveolar cells, decreasing their ability to produce surfactant.

True

True or False: A ruptured diaphragm is more common the left side than on the right.

True (left side 90% of the time)

True or False: With unilateral lung disease, PEEP may result in shunting of blood from more highly-compliant areas of the lung to lower-compliant areas, resulting in increased shunting and hypoxemia.

True. May help to have patient lying good lung side down, bad lung side up.

Normal minute ventilation, tidal volume, vital capacity, respiratory rate and NIF

Ve = 5-6 L/min Vt = 5-8 ml/kg VC = 60-80 ml/kg f = 12-20 bpm NIF = -80-100

Minute ventilation, tidal volume, vital capacity, respiratory rate and NIF indicating mechanical ventilation

Ve = >10 L/min Vt = < 5 ml/kg VC = <10-15 ml/kg f = <8 or >35 NIF = <-20-25

Diaphragmatic injury

Very rare. Almost always requires surgical repair and may require post-op mechanical ventilation. Difficult patients to wean due to diaphragmatic weakness. Usually caused by a blow to the chest or abdomen. Herniation of the abdominal contents through the diaphragm can cause impaired movement of the diaphragm, hemothorax, shock, respiratory failure, reduced lung volumes and/or strangulation of the bowel.

Near Drowning

Victim survives at least temporarily following submersion.

Important points concerning water seal bottle

Water level should oscillate while breathing. Failure may indicate obstruction or lung reexpansion.

Weaning and ARDS

Weaning is a lengthy event and fibrosis may leave lung function compromised for months. Muscle atrophy and the use of paralytic agents makes ventilatory muscles weak. Pressure support is helpful.

Radiographic studies with ARDS

X-ray may show diffuse alveolar opacity, consolidation in at least 3 quadrants. CT scan may show heterogenous disease with areas of consolidation, areas of collapse that are recruitable, areas of normal lung tissue and intrapulmonary bleb formation in some patients.

Blood gas with acute hypoxemia and hypercapnia

pH < 7.35 PaCO2 >50 HCO3 = 24 (normal) PaO2 <60

Blood gas with chronic hypoxemia and hypercapnia

pH = 7.40 (normal) PaCO2 >50 HCO3 >30 PaO2 <60

Blood gas in acute hypoxemia

pH > 7.45 PaCO2 <35 HCO3 = 24 (normal) PaO2 <60