Exam 1 B

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Questions and Answers

What is a potential complication of the lateral decubitus position?

Increased perfusion to the non-dependent lung

Increased lung compliance in the dependent lung

Decreased pulmonary blood flow to the dependent lung

V/Q mismatch due to gravity (correct)

Why is it important to periodically extend the lower legs in a patient in the lithotomy position?

To reduce the risk of lower extremity compartment syndrome (correct)

To facilitate surgical access

To prevent back pain

To improve lung compliance

What is the purpose of the axillary roll in the lateral decubitus position?

To prevent the patient from rolling off the table (correct)

To place an arterial line

To support the non-dependent arm

To facilitate surgical access to the thorax

What is a potential complication of the lithotomy position?

Lower extremity compartment syndrome Signup and view all the answers

Why is it important to pad the legs and flex them slightly in the prone position?

To reduce the risk of compression of the SVC Signup and view all the answers

What is the purpose of the bolster in the prone position?

To support the thorax Signup and view all the answers

What is a potential complication of the prone position?

Compression of the SVC Signup and view all the answers

What is the term for the position where the patient lays on their non-operative side?

Lateral decubitus Signup and view all the answers

What is the term used to describe the damage to neural and vascular structures that occurs as a result of increased pressures and decreased tissue perfusion in muscles with tight, fascial borders?

Compartment syndrome Signup and view all the answers

What is the term used to describe the anterior part of the optic nerve that is susceptible to ischemia?

Anterior ION Signup and view all the answers

What is the formula used to calculate ocular perfusion pressure?

OPP = MAP - IOP Signup and view all the answers

What is the term used to describe the injury that occurs when blood flow returns to an area after a period of ischemia?

Reperfusion injury Signup and view all the answers

What is the purpose of using transesophageal echocardiography (TEE) in preoperative evaluation?

To evaluate for patent foramen ovale (PFO) Signup and view all the answers

What is the significance of the dual blood supply to the watershed region of the optic nerve?

It decreases the risk of ischemia Signup and view all the answers

What is the term used to describe the sound heard in venous air embolism?

Mill-wheel murmur Signup and view all the answers

What is the significance of lowering the legs every 2-3 hours in the lithotomy position?

To prevent compartment syndrome Signup and view all the answers

What is a characteristic of lung volume in the posterior region compared to the anterior region?

More lung volume is present Signup and view all the answers

What is the primary mechanism responsible for nerve injuries?

Transection, compression, and stretch Signup and view all the answers

What is a consequence of venous capillary pressure rise in nerve injuries?

Slowed ATP production Signup and view all the answers

Why are peripheral nerves susceptible to ischemia?

Due to their structure and lack of lymphatic drainage Signup and view all the answers

What is a factor that contributes to nerve injuries in patients?

Age, gender, and extremes in body habitus Signup and view all the answers

What is a complication of spinal cord injuries during flexion?

Increased vertebral venous pressure Signup and view all the answers

Why is it important to avoid hyperflexion during surgery?

To prevent spinal cord injuries Signup and view all the answers

What is the name of the phenomenon characterized by postoperative visual loss?

Postoperative Visual Loss (POVL) Signup and view all the answers

What is the gold standard for detecting intracardiac shunts?

TEE Signup and view all the answers

What condition is characterized by an abnormally large tongue and can occur with excessive neck flexion?

Macroglossia Signup and view all the answers

Which surgery position is associated with a risk of venous air embolism?

Sitting Signup and view all the answers

What is a potential complication when a patient undergoes robotic surgery in steep Trendelenburg position?

Laryngeal edema Signup and view all the answers

What is the correct term for air in the cranial cavity?

Pneumocephalus Signup and view all the answers

What term describes injury to an axon within an intact nerve sheath?

Axonotmesis Signup and view all the answers

Which of the following complications is associated with prolonged exposure that inhibits capillary flow over a bony prominence?

Pressure injuries Signup and view all the answers

Which nerves are most commonly injured in the lithotomy position?

Sciatic and common peroneal nerves Signup and view all the answers

What physiological change is observed in CO and BP during general anesthesia?

Both CO and BP generally decrease Signup and view all the answers

What can pose a risk to the vena cava in the lateral decubitus position?

Elevation of the kidney Signup and view all the answers

How does a sitting or lithotomy position with extreme knee flexion affect the femoral vessels?

Can cause occlusion of femoral vessels Signup and view all the answers

What cardiovascular complication may occur with the head-down tilt in lithotomy position?

Decrease in cardiac output (CO) Signup and view all the answers

What is the effect of large tidal volumes on intrathoracic pressures and CO?

Increase intrathoracic pressures and decrease CO Signup and view all the answers

Which technique can be used to prevent hemodynamic changes during surgery?

Nitrous-narcotic technique Signup and view all the answers

Which position can lead to postoperative vision loss due to increased intraocular venous pressure?

Prone position Signup and view all the answers

What is a common ECG change associated with venous gas embolism?

Tachyarrhythmias Signup and view all the answers

What is the primary mechanism of hemodynamic changes in venous gas embolism?

Decreased cardiac output Signup and view all the answers

What is the diagnostic significance of a loud, coarse, continuous 'mill wheel' murmur?

Venous gas embolism Signup and view all the answers

What is the purpose of using transesophageal echocardiography (TEE) in venous gas embolism?

To detect intracardiac air Signup and view all the answers

What is the initial management step in suspected venous gas embolism?

Notify the surgeon immediately Signup and view all the answers

What is the purpose of providing Valsalva maneuver in venous gas embolism?

To prevent further air from entering the heart Signup and view all the answers

What is a potential complication of venous gas embolism in the cranial arterial system?

Paradoxical embolism Signup and view all the answers

What is the acronym FART in the context of venous gas embolism management?

Flood, Aspirate, Remove, Turn Signup and view all the answers

What is the primary cause of brachial nerve injury during surgery?

Ischemia secondary to stretching Signup and view all the answers

Which position is typically used for shoulder surgeries?

Beach chair Signup and view all the answers

Why should N2O be discontinued during a gasp reflex?

To prevent air embolism Signup and view all the answers

Which nerve is most commonly injured during surgery?

Ulnar nerve Signup and view all the answers

Which complication is associated with the beach chair position?

Neurologic injury Signup and view all the answers

What condition can develop from tight wound closures in the abdomen?

Compartment syndrome Signup and view all the answers

What is a potential consequence of failing to keep 2 finger breaths between the mandible and sternum in the beach chair position?

ETT obstruction and tongue swelling Signup and view all the answers

In which position should the MAP be zeroed at the tragus?

Beach chair Signup and view all the answers

Which patient position is most commonly used and least harmful?

Supine (dorsal decubitus) Signup and view all the answers

What may occur due to prolonged time in the Trendelenburg position?

Swelling in face and airway Signup and view all the answers

Which factor is the primary reason for decreased FRC in the supine position?

Cephalad displacement of the diaphragm Signup and view all the answers

In which position is the risk of elbow compression leading to ulnar nerve injury minimized?

Supine with arms out less than 90 degrees and padded Signup and view all the answers

How does insufflation affect hemodynamics?

Causes an increase in pressure which can occlude the vena cava and impair preload Signup and view all the answers

What should be checked prior to starting insufflation in surgery?

Hemodynamics Signup and view all the answers

Which of the following positions increases preload and blood pressure?

Trendelenburg Signup and view all the answers

What condition necessitates the use of an NG/OG tube during the Trendelenburg position?

Stomach above the airway Signup and view all the answers

What effect does increased abdominal pressure have on pulmonary function?

Decreased FRC and decreased pulmonary compliance Signup and view all the answers

Which type of positioning is used for surgeries that involve the rectal or anal areas?

Jackknife position Signup and view all the answers

What is the appropriate FiO2 setting to increase functional residual capacity during patient positioning?

100% Signup and view all the answers

Which complication is most commonly associated with the use of Mayfield tongs?

Subdural tear and dural bleed Signup and view all the answers

What is a potential cause of postoperative blindness?

Ischemic optic neuropathy Signup and view all the answers

What is one of the main signs of venous air embolism during surgery?

Mill wheel murmur Signup and view all the answers

Which injury is caused by direct external pressure or an internal embolus in retinal artery occlusion?

Retinal artery occlusion Signup and view all the answers

What is a purpose of using albumin in patients during prone surgery?

Decrease third spacing Signup and view all the answers

What is the most common cause of postoperative vision loss in patients undergoing prone spine surgery?

Ischemic optic neuropathy (ION) Signup and view all the answers

What condition results from ischemia to part of the optic nerve?

Ischemic optic neuropathy (ION) Signup and view all the answers

What factor is associated with an increased risk of postoperative nerve injury?

Muscular physique Signup and view all the answers

Which of the following situations is typical for the occurrence of a venous air embolism?

Sitting craniotomy Signup and view all the answers

Which procedure most commonly results in corneal abrasions?

Prone spine surgery Signup and view all the answers

What is a common consequence of improper head positioning during surgery?

Central retinal artery occlusion (CRAO) Signup and view all the answers

What preventive measure should be taken when placing a central venous pressure (CVP) line to minimize the risk of venous air embolism?

Place the patient in Trendelenburg position Signup and view all the answers

Which factor does NOT contribute to the development of venous air embolism?

High oxygen administration Signup and view all the answers

What medication should you administer if the patient becomes bradycardic and hypotensive during insufflation?

An anticholinergic such as glycopyrrolate Signup and view all the answers

What is a cause of central retinal artery occlusion (CRAO) during surgery?

Decreased blood supply to retina Signup and view all the answers

What are some risk factors for POVL?

All of the above Signup and view all the answers

What is the preferred airway management technique in the Trendelenburg position?

Video laryngoscopy with ETT Signup and view all the answers

What surgeries would you place in a patient in Reverse Trendelenburg position?

Abdominal surgery Signup and view all the answers

What is the park bench surgical position?

Semi-prone Signup and view all the answers

What is an example of a surgery that requires a patient to be in the park bench position?

Posterior fossa surgery Signup and view all the answers

Which describes the V/Q mismatch that occurs in the lateral decubitus position on the nondependent lung?

V/Q mismatch with lower perfusion and lower ventilation in the nondependent lung Signup and view all the answers

What effect does placing a patient in the lateral position have on lung ventilation and perfusion?

Decreased ventilation of the dependent lung, but increased perfusion Signup and view all the answers

What occurs in one lung ventilation?

Collapse of the non-ventilated lung Signup and view all the answers

What is the role of hypoxic pulmonary vasoconstriction in one lung ventilation?

To redirect blood flow to well-ventilated areas of the lung Signup and view all the answers

What can an improperly positioned kidney rest compress?

All of the above Signup and view all the answers

What are risk factors for rhabdomyolysis in surgery?

All of the above Signup and view all the answers

How often should eye pressure checks be performed in the prone surgical position?

q 15 mins Signup and view all the answers

What is the purpose of the cuff leak test prior to extubation?

To predict the likelihood of post-extubation stridor Signup and view all the answers

What types of devices are used in the lithotomy position?

All of the above Signup and view all the answers

What position is associated with robot surgery

steep Trendelenburg Signup and view all the answers

Study Notes

Surgical Positioning

Importance of proper positioning: preventing complications, ensuring patient safety, and facilitating surgical access
Key considerations:
- Protection of noble structures (e.g., eyes, breasts)
- Maintenance of adequate respiratory and cardiovascular function
- Prevention of pressure injuries and nerve damage

Supine Position

Most common surgical position
Complications:
- Respiratory: decreased lung compliance, elevated intra-abdominal pressure
- Cardiovascular: decreased cardiac output, increased systemic vascular resistance

Lithotomy Position

Used for pelvic, urological, and gynecological surgeries
Complications:
- Respiratory: decreased lung compliance, elevated intra-abdominal pressure
- Cardiovascular: decreased cardiac output, increased systemic vascular resistance
- Nerve injuries: sciatic and common peroneal nerves
- Pressure injuries: ischial tuberosities, sacrum, and heels

Prone Position

Used for spinal, posterior fossa, and posterior cervical surgeries
Complications:
- Respiratory: decreased lung compliance, elevated intra-abdominal pressure
- Cardiovascular: decreased cardiac output, increased systemic vascular resistance
- Nerve injuries: ulnar and brachial plexus
- Pressure injuries: chest, knees, and face

Sitting Position

Used for posterior cervical spine and posterior fossa surgeries
Complications:
- Respiratory: decreased lung compliance, elevated intra-abdominal pressure
- Cardiovascular: decreased cardiac output, increased systemic vascular resistance
- Venous air embolism (VAE)
- Nerve injuries: brachial plexus
- Pressure injuries: ischial tuberosities, sacrum, and heels

Lateral Decubitus Position

Used for thoracic, retroperitoneal, and hip surgeries
Complications:
- Respiratory: decreased lung compliance, elevated intra-abdominal pressure
- Cardiovascular: decreased cardiac output, increased systemic vascular resistance
- Nerve injuries: brachial plexus
- Pressure injuries: dependent lung, chest, and knees

Complications

Nerve injuries:
- Compression: ulnar nerve, brachial plexus
- Stretch: femoral nerve, sciatic nerve
- Transection: surgical trauma
Pressure injuries:
- Sacrum, heels, occiput (supine position)
- Ischial tuberosities, sacrum, and heels (lithotomy position)
- Chest, knees, and face (prone position)
Venous air embolism (VAE):
- Sitting position, entrainment of air into an open flowing vein or dural sinus
- Prevention: avoiding positioning above the level of the heart, mechanical ventilation, and occlusive pressure on CVP decannulation sites
Postoperative vision loss (POVL):
- Ischemic optic neuropathy (ION), central retinal artery occlusion (CRAO)
- Risk factors: prone spine operations, cardiopulmonary bypass, head and neck surgeries
- Prevention: proper head positioning, avoidance of external pressure to the eye

Prevention and Management

Prevention of complications:
- Slow assumption of the surgical position
- Nitrous-narcotic technique
- Intravascular volume loading
Management of complications:
- Recognition of signs and symptoms (e.g., VAE, POVL)
- Treatment of VAE: flooding the surgical field, occluding air entry site, and aspirating air via right atrial catheter
- Treatment of POVL: maintaining ocular perfusion pressure, avoiding hypotension and anemia### Detection of Venous Gas Embolism (VGE)
In awake patients, symptoms include coughing, dyspnea, bronchospasm, hypotension, altered mental status, and circulatory collapse
ECG changes include tachyarrhythmias, right heart strain pattern, and ST-T wave changes
Hemodynamic changes include systemic hypotension, increased CVP, and increased PA pressure
A loud, coarse, continuous “mill wheel” murmur on auscultation
Pulmonary signs and symptoms include crackles (rales) and wheezing, decreased ET CO2, and increased ET N2
Decreased arterial O2 saturation
EEG changes may be caused by cerebral hypoperfusion or paradoxical embolism to the cerebral circulation

Diagnosis of VGE

Transesophageal echocardiography (TEE) detects air in cardiac chambers
Precordial Doppler ultrasound detects gas bubbles in right heart
Presence of gas bubble in aspirate from multiorifice CVP catheter
More than one means of detection should be used in high-risk cases

Management of VGE

FART: flood, aspirate, remove nitrous, turn to lower site below heart, and turn to left side
Notify the surgeon immediately of possible VGE
Surgeon should check for possible entry sites in the wound
Attempt to aspirate gas from multiorifice CVP catheter
Administer 100% O2 and provide Valsalva maneuver
Infuse IV fluid rapidly and use vasopressors and inotropes as needed
Reposition the patient, if feasible

Cardiovascular Changes

Venous return compromised by paralysis, neuraxial blockage, PPV, and general anesthesia
Sitting, reverse Trendelenburg, and Trendelenburg positions affect cardiovascular changes

Patient Positioning

Supine (dorsal decubitus) is the most common and least harmful position for patients
FRC decreases from standing to supine
Pressure points in supine position: arms out, supinated or tucked
Frog leg position: hips and knees are flexed, and hips externally rotated
Trendelenburg and reverse Trendelenburg positions: used for laparoscopic or robotic surgery, affecting venous return, intraabdominal pressure, and FRC
Robot surgery: watch for face leaning or hitting, pad the face, and limit fluids after positioning

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Positioning - lesson 2