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Questions and Answers
What is a significant complication that can arise from mechanical ventilation?
Under which conditions is a low flow oxygen system considered acceptable?
What happens to inspired oxygen concentration as flow rate increases in a nasal cannula?
What is a potential consequence of correcting chronic hypercarbia too rapidly?
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Which complication is associated with patients on mechanical ventilation due to stress?
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What is a key identifying characteristic of anaphylaxis in IgA deficient patients?
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Which of the following symptoms is NOT typically associated with anaphylactic reactions post-transfusion?
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What is the primary management strategy for TRALI?
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What should be done for future transfusions in a patient with IgA deficiency?
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Which complication is associated with immune hemolytic transfusion reactions?
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What should the anesthetist assess to determine if a patient is in optimal condition for surgery?
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Which of the following is a potential complication following anesthesia?
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When can a patient be transported to the post-anesthesia care unit (PACU)?
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What is the primary goal in managing non-surgical disease states prior to emergency surgery?
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What should be done immediately postoperatively unless the patient is going to the ICU?
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What is the primary purpose of a bag and mask apparatus in emergency situations?
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Which type of laryngoscope blade is best suited for adults?
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When performing nasotracheal intubation, what should be considered regarding the size of the endotracheal tube (ETT)?
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What is the role of the malleable stylet during intubation?
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What is the recommended size range for an adult male's endotracheal tube?
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What is the importance of the inflatable cuff at the tracheal end of the endotracheal tube?
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Which device is used to manipulate the ETT tip during nasotracheal intubation?
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What is the maximum recommended volume for inflating the cuff of an endotracheal tube?
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What does MAC stand for in relation to anesthetic agents?
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Which anesthetic agent has the highest MAC value among the listed options?
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How is a gas mixture with a MAC of 1.0 achieved using two agents?
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What is a primary effect of volatile anesthetics on the respiratory system?
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What characteristic describes Halothane among the listed anesthetic agents?
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Which of the following agents is classified as a weak anesthetic?
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What is the primary use of volatile inhalational agents in anesthesia?
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Which statement best describes the metabolism of Isoflurane?
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Study Notes
Positive Pressure Ventilation
- Hypoventilation has many causes.
- Apnea can occur during general anesthesia.
- Muscle relaxants can cause apnea.
Pulmonary Toilet
- Used for patients who cannot clear secretions.
Pharmacology
- Can provide a route of administration for certain drugs.
Equipment Required for Intubation
- Bag and mask apparatus (e.g. Laerdal/Ambu)
- Used to deliver oxygen and manually ventilate.
- Mask sizes and shapes should be appropriate for the patient's face type and age.
- Pharyngeal airway (nasal and oral types available)
- Opens airway before intubation.
- Oropharyngeal airway prevents patient biting on tube.
- Laryngoscope
- Used to visualize vocal cords.
- MacIntosh = curved blade (best for adults).
- Magill/Miller = straight blade (best for children).
- Trachelight
- An option for difficult airways.
- Fiberoptic scope
- Used for difficult, complicated intubations.
- Endotracheal tube (ETT)
- Many different ETT types exist for different indications.
- ETTs have an inflatable cuff at the tracheal end to provide a seal, allowing positive pressure ventilation and preventing aspiration.
- Pediatric ETTs do not have a cuff because there is a natural seal at the level of the cricoid cartilage.
- The size of an ETT is marked by the internal diameter.
- Adult female: 7.0 to 8.0 mm
- Adult male: 8.0 to 9.0 mm
- Child (age in years/4) + 4 or size of child's little finger = approximate ETT size
- For nasotracheal intubation, the ETT should be 1-2 mm smaller and 5-10 cm longer.
- An ETT smaller than the predicted size should be available in case the estimate is inaccurate.
- Malleable stylet
- Available for inserting into the ETT to change the angle of the tip and facilitate the tip entering the larynx.
- Removed after the ETT passes through the cords.
- Lubricant and local anesthetic
- Optional.
- Magill forceps
- Used to manipulate the ETT tip during nasotracheal intubation.
- Suction
- With pharyngeal rigid suction tip (Yankauer) and tracheal suction catheter.
- Syringe
- To inflate cuff (10 ml).
Complications of Mechanical Ventilation
- Decreased C02 due to hyperventilation.
- Disconnection from ventilator or failure of ventilator can result in severe hypoxia and hypercarbia.
- Decreased blood pressure (BP) due to reduced venous return from increased intrathoracic pressure.
- Severe alkalemia can develop if chronic hypercarbia is corrected too rapidly.
- Water retention can occur as antidiuretic hormone (ADH) secretion can be elevated in patients on ventilators.
- Pneumonia/bronchitis (nosocomial).
- Pneumothorax.
- Gastrointestinal (GI) bleeds due to stress ulcers.
- Difficulty weaning.
Supplemental Oxygen: Low Flow Systems
- Acceptable if tidal volume is 300-700 mL, RR < 25, and ventilation pattern is steady.
- Nasal canula
- Low flow system, inspired O2 depends on flow rate and tidal volume.
- Larger tidal volume, increased RR = lower FIO2.
- For every increase from 1 L/min O2, inspired O2 concentration increases about 4%.
- E.g. with normal tidal volume, at 1-6 L/min FIO2 = 24-44%.
- Facial mask
- Low flow system, well tolerated, will have some rebreathing at normal tidal volumes.
- Minimize rebreathing by increasing flow rate.
Anaphylactic
- Rare, potentially lethal.
- Occurs in IgA deficient patients with anti-IgA antibodies.
- Immune complexes activate mast cells, basophils, eosinophils, and the complement system.
- Symptoms: Apprehension, urticarial eruptions, dyspnea, hypotension, laryngeal and airway edema, wheezing, chest pain, shock, sudden death.
- Management: Circulatory support with fluids, catecholamines, bronchodilators, respiratory assistance as indicated. Evaluate for IgA deficiency and anti-IgA antibodies. Future transfusions must be free of IgA: washed/deglycerolized RBCs free of IgA, blood from IgA deficient donor.
Transfusion-Related Acute Lung Injury (TRALI)
- A form of noncardiogenic pulmonary edema.
- Occurs 2-4 hours post-transfusion.
- Immunologic cause, not due to fluid overload or cardiac failure - is a reaction to transfusion.
- Symptoms: Respiratory distress - mild dyspnea to severe hypoxia.
- ** Chest X-ray:** consistent with acute pulmonary edema, but pulmonary artery and wedge pressures are not elevated.
- Management: Usually resolves within 48 hours with O2, mechanical ventilation, and supportive treatment.
Immunosuppression
- Some studies show associations between perioperative transfusion and postoperative infection, earlier cancer recurrence, and poorer outcome.
Immune-Hemolytic
- Most serious and life-threatening transfusion reaction.
- Caused by donor incompatibility with the recipient's blood.
Ruptured Abdominal Aortic Aneurysm (AAA)
- and Head Trauma with Increased Intracranial Pressure (ICP)
- Increased risk of needing airway management (9.4-51%).
- For emergency operations, add the letter E after classification.
- From the history, physical exam, and labs/investigations the anesthetist can determine whether or not the patient is in OPTIMAL condition for the proposed surgical procedure.
- The goal is to optimize non-surgical disease states prior to surgery.
- In emergency cases it is not always possible to optimize coexistent or chronic disease states; the goal is then to accomplish what is possible in the time available.
Postoperative Management
- Usually begins in the O.R. with discontinuation of anesthetic drugs and extubation (exception - if going to ICU).
- Patient can be transported to the post-anesthesia care unit (PACU) once ABC's are stable.
- Patient can be released from the unit when the PACU discharge criteria for ventilation, circulation, consciousness, motor function, and color have been met.
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Potential Complications:
- CNS: Agitation, delirium, somnolence.
- Respiratory: Aspiration, upper airway obstruction, hypoxemia, alveolar hypoventilation, upper airway trauma (intubation/extubation).
- CVS: Hypothermia (rewarm patient), shivering (due to hypothermia or postanesthetic effect), hypotension, hypertension, dysrhythmias.
- GI: Nausea and vomiting.
Volatile Inhalational Agents
-
Halothane, Enflurane, Isoflurane, Sevoflurane
- Liquid, colorless, non-flammable, non-explosive.
- Vaporizer delivers controlled concentration of anesthetic agents to the respiratory system of the patient via the anesthetic machine.
-
Nitrous Oxide (N2O)
- Gas, colorless, mild sweet odor at room temperature (stored as liquid under pressure).
- MAC: 104% (weak anesthetic).
- Metabolism: 0%.
- Effects: Second gas effect.
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MAC for all Volatile Agents & N2O:
- Halothane: 0.75%
- Enflurane: 1.68%
- Isoflurane: 1.15%
- Sevoflurane: 1.15%
- Nitrous Oxide (N2O): 104% (weak anesthetic)
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Metabolism for all Volatile Agents & N2O:
- Halothane: 20%
- Enflurane: 2%
- Isoflurane: 0.2%
- Sevoflurane: 0.2%
- Nitrous Oxide (N2O): 0%
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Effects for all Volatile Agents & N2O:
-
CNS:
- Volatile agents: Increase cerebral blood flow, decrease cerebral oxygen consumption.
- N2O: Second gas effect.
-
Resp:
- Volatile agents: Respiratory depression (decreased tidal volume (TV), increased rate), decreased response to respiratory CO2 reflexes, bronchodilation.
-
CVS:
- Volatile agents: Myocardial depression, vasodilatation.
-
MSK:
- Volatile agents: Muscle relaxation, potentiation of other muscle relaxants, uterine relaxation.
-
CNS:
-
Uses for all Volatile Agents & N2O:
- Volatile agents: Maintenance of anesthetic state.
- Nitrous Oxide (N2O): Analgesia, allows for the use of lower doses of more potent anesthetics.
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MACs are additive:
- E.g. 0.5 MAC of agent A plus 0.5 MAC of agent B will provide a gas mixture with a MAC of 1.0.
-
Gas concentrations are often expressed as multiples of MAC:
- E.g. if an agent has a MAC of 1.5% then 0.5 MAC = 0.75% and 2 MAC = 3.0%.
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Description
Test your knowledge on positive pressure ventilation and the essential equipment used for intubation. This quiz covers topics like hypoventilation, pharmacology related to airway management, and the tools required for effective intubation procedures. Challenge yourself to see how well you understand these critical concepts in respiratory care.
