Week 11 - General and GYN Surgery

Question 1

Why is CO2 used for insufflation?

Answer 1

Non combustible: use of peritoneal cautery

Highly blood soluble and can easily be excreted by the pulmonary system (reduces the risk of adverse outcomes in the event of a gas embolism)

*N2O administered as part of the anesthetic can diffuse into abd cavity, reaching concentrations that could support combustion

Question 2

What are the advantages to laparoscopic surgery? (10)

Answer 2

• Minimizes surgical incision and stress response
• Decreases postoperative pain and opioid requirements
• Preserves diaphragmatic function
• Improves postoperative pulmonary function
• Earlier return of bowel function
• Fewer wound-related complications
• Earlier ambulation
• Shorter hospital stays
• Early return to normal activities and work
• Reduces health costs

Question 3

What are complications of laparoscopy surgery?

Answer 3

• Pneumoperitoneum: hemodynamic and pulmonary changes, neurohumoral responses, hypercarbia
• Surgical Instruments: vascular, bowel, and GU injury, thermal injury, subQ emphysema, gas embolism, capnomediastinum and capnopericardium
• Patient Positioning: steep trendelenberg or rev. trendelenberg

Question 4

What are the anesthetic considerations for trocar placement in laparoscopic surgery?

Answer 4

• Stimulating part of the procedure – ensure adequate depth of anesthesia
• May see a vagal response with peritoneal stretch
• Always be vigilant when trocars are placed
• secondary ports are placed under direct visualization usually with trans-illumination of intra abdominal vessels

Question 5

What is the max insufflation pressure during laparoscopic surgery?

Answer 5

Insufflate to a max of 15mmHg

*Increased intra abdominal pressure due to insufflation

Question 6

How does insufflation affect SVR and MAP?

Answer 6

Initial increased SVR and MAP:

• activation of sympathetic nervous system from peritoneal stretching and systemic CO2 absorption
• compression of intra abdominal arteries
• neuroendocrine release of vasopressin, cortisol, catecholamines

*changes are sue to the mechanical compression, catecholamine response and the effect of absorbed CO2

Question 7

How does insufflation affect preload?

Answer 7

May cause a decrease in preload due to compression of venous capacitance vessels (especially in hypovolemic patients)

*may be counteracted in steep Trendelenburg and by the compression of liver and spleen which may increase intravascular volume (autotransfusion)

Question 8

What does an increased regional CO2 from insufflation cause?

Answer 8

Causes regional vasodilation which may counteract insufflation pressures

*bowel and liver perfusion usually maintained

Question 9

What rhythm changes might you see with insufflation?

Answer 9

May see bradycardia due to vagal response or tachycardia and/or arrhythmias from stress response

*monitor ECG closely

Question 10

What considerations do you need to be aware of during insufflation in a patient with severe cardiac dysfunction?

Answer 10

May see a significant reduction in CO and BP due to combination of increased SVR, HR, and decreased preload

*increased myocardial oxygen demand and increased risk for ischemia

Question 11

What are the insufflation CO2 effects?

Answer 11

Increased PaCO2 increases cerebral blood flow and ICP (especially in steep trendelenberg)

• usually not clinically significant in the healthy pt
• increased intra ocular pressures have been reported in steep trendelenberg due to choroidal vasodilation

Hypercarbia can cause pulmonary vasoconstriction and exacerbate pulmonary HTN or right heart failure

**Maintain Normocarbia

Question 12

What are the renal effects of insufflation?

Answer 12

Decreased renal blood flow, GFR, and urine output
-due to compression of renal parenchyma and neuroendocrine factors (vasopressin, cortisol, catecholamines)

Intraop oliguria usually reverses within 2 hours postop

• may be significant in renal impaired pt
• use other measurements of volume status than urine output

Question 13

What does the cephalad movement of the diaphragm during insufflation cause?

Answer 13

• Reduction in all lung volumes (restrictive pattern on flow volume loop)
• Decreased lung compliance & increased resistance
• Atelectasis (increased V/Q mismatch)
• Increased peak airway pressures
• Cephalad displacement of carina –> endobronchial intubation
• Arterial to ETCO2 gradients may increase due to increased dead space

Question 14

How does CO2 absorption during insufflation affect the respiratory system?

Answer 14

Increased minute ventilation requirements

**Greater increase during extraperitoneal than intraperitoneal laparoscopy

Question 15

When does CO2 absorption usually reach a plateau during insufflation?

Answer 15

Intraperitoneal – 10-15 minutes

Extraperitoneal – increase progressively throughout the case

Question 16

When does subcutaneous emphysema usually develop? What are the signs/symptoms?

Answer 16

• Usually develops due to dissection around the trocar (more common with more ports or multiple attempts at ports)
• If hypercapnia continues despite increased MV, laparoscopy should be interrupted to allow for de-dufflation and correction of PaCO2
• check ABGs
• resolves with discontinuation of insufflation

Question 17

What are the signs/symptoms of capnothorax?

Answer 17

• Subcutaneous emphysema of neck and thorax
• Hypotension
• Decreased oxygen saturation
• Increased peak airway pressures
• Unequal chest expansion, breath sounds
• Diagnose with thoracic ultrasound/chest xray confirmation
• Most common in procedures near the diaphragm (fundoplication and adrenorenal procedures)

Question 18

How do you treat capnothorax?

Answer 18

Stop Insufflation
100% O2
Hyperventilate!!
PEEP

*treat according to severity of compromise (intercostal cannula or chest drain if needed

Question 19

What is a CO2 embolism? What are the sings/symptoms

Answer 19

Inadvertent IV placement of veress needle or passage of CO2 into abdominal wall and intraperitoneal vessels

S/S: hypotension, hypoxemia, arrhythmia, decrease ETCO2 (air lock), Mill wheel murmur

Question 20

How do you treat CO2 Embolism?

Answer 20

• Deflate abdomen
• Hyperventilate
• Cardiopulmonary resuscitation
• Turn pt to left lateral decubitus, Trendelenburg position (allows embolus to rise into the apex of the right ventricle and prevents entry into pulmonary artery)
• Aspirate embolus out of RA through central line

Question 21

What complications are associated with steep Trendelenburg in laparoscopic surgery?

Answer 21

• Facial, pharyngeal, and laryngeal edema (limit fluids, keep intubated, protect eyes from gastric fluid)
• Increased ocular pressure with venous congestion has led to visual loss
• Brachial plexus injury

Question 22

What are the neuraxial anesthetic considerations for laparoscopic procedures?

Answer 22

• high level required (T2)
• patients still have discomfort with insufflation
• obese or lung disease pt are unable to compensate for increased PaCO2 and trendelenberg position
• doesn’t cover referred shoulder pain due to diaphragmatic irritation

Question 23

What type of anesthesia is preferred in laparoscopic procedures?

Answer 23

General Anesthesia

• paralysis may help increase lung compliance
• ETT preferred

Question 24

What are controlled ventilation considerations for laparoscopic surgery?

Answer 24

• Flow volume curve looks the same, just smaller (restrictive pattern)
• Pressure volume curve will display decreased compliance
• Pressure Control (lung protective?) vs Volume Control vs PCVG
• PEEP 5-10 has been shown to improve oxygenation
• May need PIP of up to 50
• Smaller tidal volumes w/ faster rates
• Increased MV (20-30%) but maintain ETCO2 in high normal range (45)
• Longer inspiratory time may help get better volume for pressure (be sure to not breath stack)
• Maintain paralysis in longer cases

*maintaining higher ETCO2 may improve tissue oxygenation from resulting increased CO and vasodilation and shift of oxyhemoglobin dissociation curve to the right

Question 25

What are anesthetic considerations during the maintenance phase for laparoscopic procedures?

Answer 25

• Arms often tucked – make sure you have good IV access
• Bilateral NIBP cuffs
• A-line for those who have significant cardiopulmonary disease
• Vigilant positioning (padding pressure points)
• Fluid management (goal directed, fluid minimization in head down position until pt is returned flat) – UO may not be good indicator of volume status

Question 26

There is a higher risk for PONV with laparoscopic surgery… what can you do to help prevent it?

Answer 26

Multimodal Therapy:

• dexamethasone (0.1-.15 mg/kg) up front
• acetaminophen (oral before or IV at end)
• ketamine? Low dose 0.25-0.5 mg/kg
• zofran at end. Consider scope patch and other therapies.
• infiltration of incisions with local
• usually no RA (TAP block?)
• IV lidocaine?

Question 27

What are the considerations for pain in laparoscopic general surgery?

Answer 27

Pain is primarily visceral and not incisional

Shoulder pain due to referred diaphragm irritation

Don’t treat every increase in HR or BP w/ opioid (esmolol is a good option)

Opioid-induced spasm of the sphincter of Oddi may be reversed by glucagon

Question 28

What are the disadvantages of open abdominal procedures?

Answer 28

• Significantly more pain (multimodal, regional including epidurals for postop pain, TAP blocks)
• More potential for blood loss
• More potential for 3rd space fluid loss?
• More potential for postop respiratory issues
• Maintain paralysis until muscle layer is closed