Clinical Anesthesia | Anesthesia Techniques Flashcards
This deck is intentionally tailored from the In-service exam format of PBA. The focus is on anesthesia technique both in clinical and theoretical.
The following indicators means that extubation in myasthenia gravis may be unsafe
These are the indicators that it is UNSAFE to extubate a MG patient
-25 Peak inspiratory pressure or less
2L vital capacity (or less)
6 years of having the disease
750mg or more of physostigmine daily
In a patient under general anesthesia, signs of FAT EMBOLISM SYNDROME are few. Which of the following is a sign of an acute fat embolism syndrome?
A. Hypertension
B. Decreased A-a gradient
C. Bradycardia
D. Fever
E. Increased A-a gradient
E. Increased A-a gradient
In a patient under general anesthesia, the signs are few but include hypoxia, increased A-a gradient, tachycardia, and a petechial rash on the upper body. If the fat embolism is large enough, fat, blood components and bony particles travel via the venous system to the right side of the heart and become lodged in the pulmonary arteries, causing increased afterload against which the right ventricle must pump. The right ventricle acutely dilates and fails as it is accustomed to performing low pressure, volume work.
You are caring for a postpartum patient with a retained placenta. The obstetrician is having difficulty with manual removal of the placenta and requests uterine relaxation. Assuming this patient is hemodynamically stable, administration of which of the following agents is the MOST appropriate initial therapy to facilitate uterine relaxation?
(A) Fentanyl (B) Halothane (C) Nitroglycerine (D) Ketamine
C. Nitroglycerine
Classically, general anesthesia with tracheal intubation and administration of high-dose volatile agents (classically halothane) was used to facilitate uterine relaxation. Administration of any volatile anesthetic will result in dose-dependent uterine relaxation and may be necessary under certain circumstances; however, these agents expose the patient to the increased risk associated with general anesthesia in the obstetric population (ie, difficult intubation and aspiration). In addition, once uterine relaxation is achieved with inhalational agents it may be difficult to reverse the effect.
Most anesthesiologists now recommend administration of nitroglycerin in a case such as this. Multiple studies and reports have demonstrated its effectiveness for this indication. Nitroglycerin appears to act through release of nitric oxide, which in turn leads to relaxation of uterine smooth muscle. It has also been demonstrated that the presence of placental tissue enhances uterine relaxation. The effects of nitroglycerin are almost immediate and will dissipate quickly. The most common side effect is transient hypotension, which is typically of very short duration and can be easily treated. Nitroglycerin is most commonly administered intravenously in 50-150 mcg boluses until relaxation is achieved. Alternatively, use of a sublingual spray or tablets (800 mcg) has been described.
Both ketamine and fentanyl in small doses can be used as sedatives for examination and manual removal of a placenta. However, neither agent results in relaxation of uterine smooth muscle.
In which of the following situations is work of breathing MOST efficient with slow, deep breaths?
(A) Pulmonary fibrosis (B) Aspiration pneumonia (C) Pulmonary edema (D) Chronic obstructive lung disease
D. Chronic obstructive lung disease
During spontaneous breathing the muscles of respiration effectively perform work by overcoming resistance to motion from two sources:
- Elastic resistance from the lung parenchyma and chest wall
- Frictional resistance to gas flow occurring in the airways
Classic teaching is that under normal conditions (spontaneous ventilation, absence of lung disease) all the work of breathing occurs during inspiration; exhalation is a passive process.
Assuming that minute ventilation is constant, there is a respiratory rate at which the work of breathing is minimal for a given combination of pulmonary compliance and airway resistance. Rapid, shallow breaths are more efficient in the presence of decreased lung compliance (eg, pulmonary fibrosis, aspiration pneumonia, pulmonary edema). Slow, deep breaths are more efficient in the presence of increased airway resistance (eg, asthma, chronic obstructive lung disease).
KEYWORD:
Decreased Compliance: Rapid, shallow breaths are more efficient.
Increased Compliance: Slow. deep breaths are more efficient.
Which of the following pulmonary artery occlusion pressure waveform findings would MOST likely be present during left ventricular ischemia?
A. Increase in the width of the a wave
B. Increase in the height of the a wave
C. Decrease in the width of the v wave
D. Decrease in the height of the v wave
B. Increase in the height of the a wave
A pulmonary artery catheter with balloon inflated results in pulmonary artery occlusion, which produces a characteristic waveform pattern that (ideally) represents pressure changes in the left atrium throughout the cardiac cycle and left ventricular pressure at end-diastole. Increases in atrial pressure are represented as waves; decreases in atrial pressure are represented as descents.
Which statement about the differences between the respiratory system in healthy infants and adults is MOST likely TRUE?
A. Infant dead space as a fraction of body weight is substantially larger than that of adults
B. Infant work of breathing is greater than that of adults
C. Closing capacity is a similar fraction of total lung capacity in infants and adults
D. Functional residual capacity as a fraction of body weight is smaller in infants than in adults
B. Infant work of breathing is greater than that of adults
There are important anatomic and physiologic differences between infant and adult respiratory systems. Anatomically, the infant has a larger head and tongue, a more flexible epiglottis, and a more anterior laryngeal position with a narrower cricoid cartilage. Additionally, the rib cage is more compliant in infants, resulting in an increased work of breathing, which places infants at a higher risk for respiratory muscle fatigue, especially in conditions such as airway obstruction and pneumonia.
In addition to these anatomic differences, there are several important physiologic differences between the respiratory systems of infants and adults. Infants have a larger oxygen consumption, closing capacity, respiratory rate, and alveolar minute ventilation with a similar functional residual capacity per body weight compared to adults.
These properties have important implications during periods of apnea and inhalational anesthesia induction.
Which statement about the use of epidural 2-chloroprocaine for cesarean delivery is MOST likely true?
A. It enhances the efficacy of epidural morphine
B. It is contraindicated when late fetal heart rate decelerations are present.
C. The risk of systemic toxicity is increased in a woman homozygous for atypical plasma cholinesterase.
D. The ethylenediaminetetraacetic acid (EDTA) present in some formulations of 2-chloroprocaine causes neurotoxicity
A. It enhances the efficacy of epidural morphine
An ester local anesthetic, 2-chloroprocaine is characterized by rapid onset and short duration or action. In certain clinical scenarios, its unique characteristics make it the preferred local anesthetic for epidural anesthesia. It is rapidly hydrolyzed by plasma cholinesterase to the inactive metabolites 2-chloroaminobenzoic acid and 2-diethylaminoethanol.
Because of its rapid metabolism, minimal placental transfer of the drug occurs. This reduces the problem of fetal “ion trapping” this is associated with the use of amide local anesthetics in the setting of fetal acidosis.
Ion trapping occurs when the un-ionized local anesthetic agent crosses the placenta, becomes ionized in the relatively acidic fetal milieu, and cannot diffuse back through the placenta, thereby resulting in higher local anesthetic concentrations in the fetus.
Therefore, in the presence of late fetal heart rate decelerations, which suggests fetal acidosis, 2-chloroprocaine would be the preferred local anesthetic for cesarean delivery. Use of the drug would expedite delivery of the compromised fetus while minimizing ion trapping.
Atlantoaxial subluxation is diagnosed when the distance between the:
A. anterior arch of the atlas and the odontoid process is >3mm
B. posterior arch of the atlas and the odontoid process >5mm
C. posterior arch of the axis and the odontoid process is >3mm
D. anterior arch of the axis and the odontoid process is >5mm
A. anterior arch of the atlas and the odontoid process is >3mm
Atlantoaxial subluxation is diagnosed when the distance between the anterior arch of the atlas and the odontoid process is > 3 mm
What type of channelopathy is the main culprit in Hyperkalemic periodic paralysis:
A. Na+ channel myopathy
B. K+ channel myopathy
C. Ca+ channel myopathy
D. Cl- channel myopathy
A. Na+ channel myopathy
It is an autosomal dominant channelo-pathy caused by a mutation of the sodium channel.
The muscles responsible for respiration are usually
spared
The use of potassium-wasting drugs such as thiazide diuretics or carbonic anhydrase inhibitors, along with maintaining a diet of carbohydrate-rich meals, can help prevent episodes.
What type of channelopathy is the main culprit in Hypokalemic periodic paralysis:
A. Na+ channel myopathy
B. K+ channel myopathy
C. Ca+ channel myopathy
D. Cl- channel myopathy
C. Ca+ channel myopathy
Hypokalemic periodic paralysis (hypoPP) is also autosomal dominant and is the result of mutations in both calcium ion (most common) and sodium ion channels.
Patients begin having episodes of weakness, usually in their teenage years; these episodes last hours to days and are the result of a low serum potassium concentration. Proximal muscles are most often affected, while the diaphragm and muscles supplied by the cranial nerves are spared.
What type of channelopathy is the main culprit in Andersen–Tawil syndrome?
A. Na+ channel myopathy
B. K+ channel myopathy
C. Ca+ channel myopathy
D. Cl- channel myopathy
B. K+ channel myopathy
Andersen–Tawil syndrome (ATS) is caused by a mutation in the potassium ion channel of skeletal muscle.
This results in a periodic flaccid paralysis
similar in presentation to hypokalemic periodic paralysis.
Unlike other channelopathies, Andersen-Tawil Syndrome affects the smooth muscle such as the cardiac muscles. May present with arrhythmia.
A 20 year old male is scheduled for an elective hernia repair. Preoperatively, the patient claimed to have had episodes of flaccid paralysis. His weakness occurs spontaneously following prolonged rest or following rest after exertion. Diagnostics revealed a potassium of <3.0 sodium 133. You suspected a hypokalemic type of channelopathies and decided to proceed with the anesthesia plan. Which of the following DOES NOT have a role in the anesthetic plan for this patient:
A. Glucose loading should be avoided
B. Succinylcholine may be used with careful NMB monitoring
C. Diuretics may precipitate paralytic events and should be used with caution
D. MH precautions are not necessary for all
patients with a channelopathy
B. Succinylcholine may be used with careful NMB monitoring
Succinylcholine should not be administered, both due to its tendency to increase serum potassium levels and the risk of exaggerated contractures in
patients with nondystrophic myotonias.
These contractures have at times been misdiagnosed as signs of MH. MH precautions are not necessary for all patients with a channelopathy.
In the case of hyperPP and hypoPP, knowing the patient’s baseline and preoperative serum potassium is important, as most adverse events are
related to changes in potassium concentration.
An otherwise healthy 45-year-old woman is seen at an ambulatory surgical center for release of Dupuytren’s contracture. A brachial plexus block is performed using the axillary approach. Assuming that no other nerve blocks are performed, and that the axillary block successfully achieves a complete motor and sensory block in its intended distribution, which of the following motor responses in the blocked extremity would MOST likely still be present?
A. 1st-5th digit adduction
B. Wrist flexion
C. Forearm supination
D. Extension of the MCP joints
C. Forearm supination
At the level of the axillary artery, the brachial plexus has divided into three cords (medial, lateral, and posterior), which are named in relationship to the axillary artery. These three cords travel with the axillary artery within the axillary sheath. The musculocutaneous nerve, however, as a terminal branch of the lateral cord, travels separately and is NOT located inside the axillary sheath.
Thus, it must be blocked separately from an axillary brachial plexus block. Assuming that a musculocutaneous nerve block has not been performed, we would not expect to see a motor block of the biceps muscle, and elbow flexion and forearm supination, as well as cutaneous sensation to the lateral forearm, would be intact.
