Apex Master Flashcards

Everything I need to know from Apex for SEE, NCE, and clinicals.

In Neurosurgical patients, how does patient position affect the risk of venous air embolism?

The risk of VAE is highest in the sitting position. Followed by Supin > Prone > Lateral (lowest risk).

How is Pulmonary artery HTN specifically defined?

Mean pulmonary artery pressure (PAP) > 25 mmhm.

(Normal is less than 20 mmHg at rest.)

What’s the definitive treatment for a pneumothorax, once the immediate emergency is addressed?

The definitive treatment for a pneumothorax, after creating an opening to relieve tension, is placement of a chest tube.

(The chest tube allows for continuous drainage of air or fluid, promoting lung re-expansion.)

How would you explain the core issue in restrictive lung disease?

Restrictive lung disease is characterized by a proportionate reduction in all lung volumes along with poor compliance, meaning the lungs struggle to expand during inspiration.

(It can be caused by intrinsic factors like pulmonary fibrosis or extrinsic factors such as obesity or pleural effusion.)

What is the defining characteristic of a flial chest?

Flail chest is a consequence of blunt chest trauma with multiple rib fractures, characterized by paradoxical movement of the chest wall at the injury site.

(This paradoxical movement occurs when the affected segment moves inward during inhalation and outward during exhalation, compromising respiratory mechanics and leading to respiratory distress.)

If you suspect a pneumothroax during a procedure, what should you do immediately regarding nitrous oxide?

You must discontinue nitrous oxide immediately upon suspicion of a pneumothorax because it can rapidly expand the air-filled space, worsening the condition.

(This could lead to increased intrathoracic pressure and further compromise respiratory function.)

What 2 distinct conditions are encompassed by the term COPD?

COPD is an umbrella term that includes both chronic bronchitis and emphysema.

What PaCO2 level is a strong indicator for mechanical ventilation?

A PaCO2 level greater than 60 mmHg indicates respiratory failure and is a strong indicator for mechanical ventilation.

(This level suggests inadequate ventilation and may lead to severe acidosis.)

What’s the primary treatment for carboxyhemoglobinemia?

The primary treatment for carboxyhemoglobinemia is hyperbaric oxygen therapy, which helps to reduce carbon monoxide levels in the blood and alleviate symptoms.

(This therapy enhances the elimination of carbon monoxide at higher pressures, improving oxygen delivery to tissues)

Can you explain how the vagus nerve affects airway diameter?

The vagus nerve (PNS) releases acetylcholine, which stimulates M3 receptors on airway smooth muscle to decrease its diameter, leading to bronchconstriction.

How much stronger is carbon monoxide’s binding affinity for HGB compared to O₂?

Carbon monoxide's binding affinity for hemoglobin (HGB) is approximately 200-250 times stronger than that of oxygen (O2).

(This significantly impairs oxygen transport in the blood. This higher affinity leads to reduced oxygen delivery to tissues, causing hypoxia.)

Should a patient’s preoperative medications for pulmonary hypertension be held before surgery? Why?

No, preoperative medications that reduce PVR should NOT be held in patients with pulmonary hypertension because they are essential for maintaining hemodynamic stability during the procedure.

What’s the most sensitive diagnostic tool for detecting a venous air embolism (VAE)? How?

Transesophageal echocardiography (TEE) is the most sensitive diagnostic tool for detecting a venous air embolism (VAE).

(It can visualize air bubbles in the right heart and pulmonary circulation.)

How is asthma fundamentally defined?

Asthma is defined as an acute, reversible airway obstruction accompanied by chronic airway inflammation and bronchial hyperactivity.

(It is characterized by episodes of wheezing, coughing, chest tightness, and shortness of breath.)

What are some common reasons why a patient might need a tracheal resection?

Tracheal resection is indicated for tracheal stenosis, tracheomalacia, tumors, vascular lesions, and congenital malformations.

What inspiratory force value suggests the need for mechanical ventilation?

an inspiratory force < 25 cmH2O is a strong indication for technical ventilation.

What is an absolute contraindication for performing a mediastinoscopy?

Previous mediastinoscopy is an absolute contraindication due to scarring.

(Mediastinoscopy is a surgical procedure used to examine the mediastinum, the area between the lungs that contains the heart, trachea, esophagus, and other structures. It involves inserting a mediastinoscope through a small incision above the sternum to obtain biopsies or assess lymph nodes and other conditions.)

What does the diffusing capacity test (DLCO) actually tell us about the lungs?

DLCO measures how well gases can transfer across the alveolocapillary membrane, indicating the efficiency of gas exchange.

(It can help diagnose conditions like pulmonary fibrosis, emphysema, and pulmonary hypertension.)

If a patient becomes hypoxemic during one-lung ventilation, what’s the very first thing you should check?

The first step is to verify that 100% oxygen is being delivered to the patient.

(Since only one lung is being ventilated, the ability to effectively oxygenate the blood decreases. By providing 100% oxygen, you increase the oxygen available for absorption into the bloodstream, compensating for any potential hypoxemia that might occur due to lack of ventilation in the other lung.)

What’s the recommended tidal volume for mechanically ventilating a COPD patient?

Tidal volume of 6-8 mL/kg of ideal body weight is recommended.

(This helps prevent barotrauma and ensures adequate ventilation.)

What are the 2 main types of direct-acting bronchodilators, and how do they generally work?

Direct-acting bronchodilators include beta₂-agonists and anticholinergics.

Beta₂-agonists stimulate beta receptors in the airway smooth muscle, leading to relaxation and bronchodilation

Anticholinergics block acetylcholine action, reducing bronchoconstriction.

What’s the recommended fluid management strategy for ARDS patients?

A conservative fluid management strategy is recommended for ARDS patients to support oxygenation by reducing hydrostatic pressure, thereby preventing further pulmonary edema and improving gas exchange in the pulmonary capillaries.

What 4 physiological conditions should we try to avoid because they increase PVR?

Physiological conditions that should be avoided to prevent increased pulmonary vascular resistance (PVR) include hypoxia, hypercapnia, acidosis, and hypothermia. These conditions can lead to vasoconstriction and decreased perfusion efficiency.

What’s the outcome if a DLT is accidentally placed in the wrong bronchus?

If a DLT is in the wrong bronchus, the intended operative lung will be ventilated, while the non-operative lung will collapse.

What’s the most common cause of a hemothorax?

Hemothorax is most commonly caused by bleeding from intercostal vessels.

What are the 4 main causes or risk factors for developing COPD?

• Cigarette smoking

• Respiratory infections

• Exposure to environmental pollutants

• Alpha1 antitrypsin deficiency

How is flail chest primarily treated?

treatment focuses on reducing pain using epidural or intercostal nerve blocks, with some patients requiring mechanical ventilation and surgical fixation.

What’s considered the biggest risk factor for developing asthma?

Atopy, which is the condition of being ‘hyper-allergic’, is the greatest risk factor for developing asthma.

(It is often associated with elevated IgE levels and allergic reactions, leading to an exaggerated immune response.)

What’s the key difference between static and dynamic lung volumes, and why do we measure both?

Static lung volumes measure how much air the lungs can hold at a single point. (Quantity)

Dynamic volumes measure how quickly air moves, assessing airflow resistance and lung recoil. (Speed)

What exactly is dynamic hyperinflation, and what’s another name for it?

Dynamic hyperinflation occurs when a new breath is delivered before the patient fully exhales the previous one, leading to ‘breath stacking’.

What are the main classes of anti-inflammatory medications used for pulmonary conditions?

• inhaled corticosteroids

• cromolyn (stabilizing mast cell membranes, preventing the release of histamine and other inflammatory mediators)

• leukotriene modifiers (block the action of leukotrienes, which are inflammatory chemicals that lead to bronchoconstriction and inflammation in the airways.)

What’s the single best way to prevent ventilator-associated pneumonia (VAP)?

The best method to prevent VAP is to avoid intubation altogether and use non-invasive ventilation when possible.

What’s the immediate intervention for dynamic hyperinflation?

For immediate treatment of dynamic hyperinflation, you should disconnect the patient from the breathing circuit to allow lung pressure to equalize with atmospheric pressure and facilitate exhalation.

When is aspiration most likely to occur during an anesthetic?

Aspiration most commonly occurs during anesthetic induction, intubation, or within 5 minutes of extubation.

What respiratory rate ranges are strong indicators for mechanical ventilation?

An RR > 40 BPM or < 6 BPM is considered critical and warrants mechanical ventilation.

If all other interventions fail to resolve severe hypoxemia during one-lung ventilation, what is the definitive last resort?

The definitive last resort is to convert to two-lung ventilation.

(This involves removing the lung isolation device to reinflate both lungs and improve oxygenation.)

What are the main problems that can arise from aspiration of gastric contents?

Aspiration can lead to airway obstruction, bronchospasm from chemical burn, impaired gas exchange, and bacterial respiratory infections.

Who are the 3 main groups of patients at risk for carboxyhemoglobinemia?

Patients at risk for carboxyhemoglobinemia include burn victims, smokers, and those exposed to desiccated soda lime.

What are the most common pulmonary and extrapulmonary causes of ARDS?

Pneumonia is the most common pulmonary etiology, and sepsis is the most common extrapulmonary cause of ARDS.

What happens if a DLT is not inserted deep enough?

If a double-lumen tube (DLT) is not inserted deep enough and remains in the trachea, it will fail to achieve adequate lung separation.

Why is a mediastinoscopy performed?

A mediastinoscopy is performed to obtain tissue samples from the mediastinum for diagnosis and to stage the extent of lung cancer.

Why are flow-volume loops so useful in respiratory diagnostics?

Flow-volume loops help distinguish between obstructive and restrictive lung diseases by visualizing airflow rates at different lung volumes.

What vital capacity value is a strong indicator for mechanical ventilation?

A vital capacity value of <15 mL/kg is a strong indicator for mechanical ventilation.

What’s the general guideline for sizing a double-lumen ETT for a female patient based on height?

• 35 French DLT if < 160 cm

• 37 French DLT if > 160 cm

Name 5 anesthetic agents that actually help promote bronchodilation?

• Sevoflurane

• Isoflurane

• Ketamine

• Propofol

• Lidocaine

What are the normal expected values for FEV1 and the FEV1/FVC ratio?

• FEV1 is > 80% (measures the volume of air a person can forcibly exhale in one second)

• FEV1/FVC ratio between 75-80% (measures the proportion of a person's vital capacity that they can exhale in the first second of forced expiration. It is used to determine the presence of obstructive or restrictive lung diseases)

Why is the radius of an airway such a huge deal for how much air can flow through it?

According to Poiseuille's law, Airflow resistance is inversely proportional to radius raised to the fourth power, meaning small changes in radius drastically affect resistance and airflow.

What’s the general guideline for sizing a double-lumen ETT for male patient based on height?

39 French DLT < 170 cm

41 French DLT > 170 cm

In simple terms, what’s the main problem in obstructive lung disease?

Obstructive disease involves small-airway obstruction and increased expiratory flow resistance, making it difficult for the patient to get air out.

(This leads to reduced FEV1 and a decreased FEV1/FVC ratio)

How should ventilator-associated pneumonia (VAP) be treated?

VAP treatment begins with broad-spectrum antibiotics (ex: Cefepime, meropenem, Zosyn, Levofloxacin) targeting common ICU organisms, followed by targeted therapy once the specific pathogen is isolated.

What are the 3 main types of pneumothorax?

• Closed - air is trapped in the pleural space without direct communication with the outside environment, typically due to lung disease or injury (like a spontaneous pneumothorax). The lung can still collapse due to the loss of negative pressure.

• Communicating (open) - there is a direct connection between the pleural space and the outside environment, such as through a gunshot or stab wound. This allows air to enter and exit the pleural cavity, preventing the lung from fully expanding.

• Tension - air enters the pleural space but cannot escape, leading to increased intrathoracic pressure. Life-threatening emergency that requires immediate intervention.

If intubation is necessary, what’s the next best strategy to prevent VAP?

If intubation is unavoidable, the next best preventable measure for VAP is to minimize the duration of mechanical ventilation.

What’s the recommended target oxygen saturation range when giving supplemental oxygen to severe COPD patients to avoid hypercapnia?

The recommended target oxygen saturation range for severe COPD patients receiving supplemental oxygen is typically between 88% and 92% to prevent hypercapnia.

How is ARDS fundamentally defined?

A form of non-cariogenic pulmonary edema, diagnosed using the Berlin definition.

What’s the fundamental characteristic that defines COPD, distinguishing it from conditions like asthma?

COPD is characterized by reduced maximal expiratory flow and slower forced emptying of the lungs.

Unlike asthma, this airflow obstruction is not reversible.

Name 3 key patient-related risk factors for postoperative pulmonary complications?

• > 65

• COPD

• CHF

How is restrictive lung disease generally defined?

An umbrella term for disorders that impair normal lung expansion during inspiration, affecting areas like the interstitial, pleura, or rib cage.

List some of the key pathophysiologic features of ARDS?

• Protein-rich pulmonary edema

• Loss of surfactant

• hyaline membrane formation

• Increased alveolar permeability

What are the 3 immediate first steps in treating acute intraoperative bronchospasm?

• 100% FiO2

• Deepen anesthetic

• Administer short-acting inhaled beta2 agonist

Why is nitrous oxide a concern for COPD patients?

Nitrous oxide is associated with rupture of pulmonary blebs, increasing the risk of pneumothorax due to its insolubility and rapid expansion into air-filled spaces.

How does carbon monoxide affect the oxyhemoglobin dissociation curve?

Carbon monoxide binds to hemoglobin with a much greater affinity than oxygen, shifting the oxyhemoglobin dissociation curve to the left. This results in reduced oxygen delivery to tissues despite increased affinity for oxygen.

If a patient needs to be reintubated after a tracheal resection, what’s the safest method?

Flexible fiberoptic bronchscop