anesthetic management of robotic procedures in steep trendelenburg Flashcards
1
Q
what are advantages of robotic surgery
A
- reduced blood loss
- reduced physiologic tremor or surgeon
- greater scale of hand movements
- greater hand eye coordination
- seven degrees of freedom of the instruments
- surgeon can sit with reduced fatigue
- 3D, HD stereotactic vision
- greater depth perception
2
Q
what are advantages of robotic surgery
A
- reduced blood loss
- reduced physiologic tremor or surgeon
- greater scale of hand movements
- greater hand eye coordination
- seven degrees of freedom of the instruments
- surgeon can sit with reduced fatigue
- 3D, HD stereotactic vision
- greater depth perception
3
Q
what are disadvantages of robotic procedures
A
- higher costs
- lengthy set up, patient positioning, and prep time
- inefficient with some surgeries compared to conventional laparoscopy
- bigger operating room required
- trocar placement not cosmetically favorable
- limited direct access to patient
- no feedback regarding tactile or force
- not easily converted to open in emergency
4
Q
what is the triple threat?
A
altered physiology with 3 positions:
- lithotomy
- abdominal insufflation
- steep trendelenburg
5
Q
what is steep trendelenburg?
A
> 30 degrees, max 45 degrees tilt head down
6
Q
why is steep trendelenburg used in robotic procedures?
A
-maximal surgical exposure and optimal visualization
7
Q
what position is prostate, colon, and GYN surgeries usually performed in?
A
max position (45 degrees)
- once robot is docked, table movement requires undocking (or trocar will rip where placed in pt.)
- surgeons avoid readjusting if more trendelenburg is needed
8
Q
what are the effects of steep trendelenburg on the pulmonary system?
A
- abdominal contents shift cephalad
- diaphragm can shift cephalad as much as 8-10 cm
- trachea shortens; ETT may migrate to Rt. main branch
- reduced pulmonary compliance and FRC
- worsening ventilation-perfusion mismatch (shunt, perfusion w/o ventilation)
- PIPs increase as much as 50%
- chest binding and high insufflation pressures further reduce compliance (along with ST, up to 68%)
9
Q
what insufflation pressures are recommended?
A
10
Q
how does the pneumoperitoneum (abdomen insufflation) affect the pulmonary system
A
- increased intra abdominal pressure
- CO2 acting as a drug
- pulmonary management strategies must consider additional CO2
- elevated CO2 after deflation is explained by large amounts of CO2 stored in extravascular compartments of body slowly redistributing or exhaled
11
Q
what has been shown to improve oxygenation after prolonged pneumonperitoneum?
A
PEEP of 5 cmH2O
12
Q
how can the pt. in ST be ventilated?
A
- volume control or pressure control ventilation
- volume control leads to increased PiPs
- pressure control found to be more efficient resulting in lower PiPs and higher dynamic compliance
- lowering Vt and increasing RR are strategies used to maintain adequate ventilation
13
Q
what caution needs to be taken with PCV?
A
- use volume control
- inadequate Vt if PC setting is too low
- excessive Vt can lead to volutrauma when pneumoperitoneum is released
14
Q
what are intraocular effects of ST?
A
- debate whether autoregulation maintains OPP (MAP-IOP or CVP, whichever higher)
- increased ocular pressure has resulted in: retinal detachment, posterior ischemic optic neuropathy
- elderly have a higher baseline IOP
- hypotensive ischemic optic neuropathy: may be combination of periorbital edema and increased venous congestion leading to a compartment syndrome of optic nerve
- reduced ocular perfusion pressure r/t prolonged ST
- Hespan (colloid) used to help hold fluid in vascular compartment decreasing cerebral congestion
- very long cases may lead to vision loss
15
Q
why is the CV system not the biggest concern with ST?
A
body often compensates for changes
16
Q
what should be suspected with pneumoperitoneum if sudden CV collapse with capnograph changes?
A
venous CO2 gas embolism
-sudden drop in BP and capnograph flattens out
17
Q
what increases emboli risk with pneumoperitoneum?
A
- CO2 > 50 mmHg
- six or more ports
- operative time > 200 minutes
- older pt.
18
Q
when is venous emboli more common with pneumoperitoneum?
A
- initial insufflation
- dissection of deep venous tissue
19
Q
what can CO2 buildup after pneumonperitoneum cause?
A
- CO2 subcutaneous emphysema
- postop shoulder pain: residual CO2 irritating phrenic nerve
- direct compression of renal vasculature leading to decreased: UOP, creatinine clearance, GFR, RBF
- all lead to renal dysfunction
- some surgeons will squeeze abdomen after to get extra CO2 out
20
Q
what are cerebrovascular effects of robotic surgery?
A
- elevated PaCO2: absorption of CO2 leads to cerebral vasodilation and increased cerebral blood flow
- adds to venous congestion
21
Q
what are cerebrovascular effects of pneumonperitoneum with robotic surgery?
A
abdominal compression causes reduced venous outflow
*adds to venous congestion
22
Q
what are the cerebrovascular effects of ST?
A
- gravitational forces cause a reduction in venous return
- cranial drainage reduced
- CT scans have shown cerebral edema
23
Q
what are intracranial effects of both trendelenburg and pneumonperitoneum?
A
- intracranial HTN
- reduction in regional cerebral oxygenation (rSO2) in elderly
- autoregulation may preserve and even increase rSO2 and CPP in healthy pts. with no intracranial pathology d/t increased CBF
24
Q
what helps preserve cerebrovascular homeostasis?
A
normocarbia
25
when are cerebral ischemia risks elevated?
subjects with cerebral vascular disease or increased ICP
26
describe positioning complications with ST
- sliding cephalad; greater risks in morbidly obese
* can cause tearing of port incision site
- brachial plexus stretch from shoulder straps/braces (no longer recommended)
* X pattern for chest straps preffered over shoulder braces
- ischemic necrosis of occiput leading to alopecia
27
describe robotic positioning relationship to lower extremity nerve injury
- nerve injuries from overstretching or compression
* common peroneal nerve most common complication in lithotomy position
- other nerves at risk: femoral, obturator, sciatic
28
how does prolonged lithotomy and ST contribute to rhabdomyolysis?
- hypoperfusion of lower extremities comparable to compartment syndrome
- rhabdomyolysis forms from muscle ischemia
- elevated serum creatinine kinase levels
- gluteal, back, and shoulder muscles at greater risk r/t sheer force
- higher risk in BMI > 30 d/t sheer force
29
how is the face affected by robotic procedures?
- robotic arms may contact face if ports are placed high esp. camera port
- nose, mouth vulnerable to injury
* corneal abrasion most common ocular complication (most d/t failure of eyelid to close causing corneal drying, esp. if eyes bulge from increased fluid and tape sticks to cornea)
- face masks, eye shields, foam padding to head have helped
- corneal very sensitive to hypoxia and dryness (lubricate?)
- tightly applied foam or misaligned eye protector can cause hypoxia
- desquamation of epithelial layer more readily induces abrasion
30
how does ST position affect airway?
- ETT can migrate into the bronchus after insufflation d/t tracheal shortening
- most patients awaken with some degree of facial, pharyngeal and laryngeal edema from venous congestion
* *high degree of facial and conjunctiva edema may indicate laryngeal edema
- post extubation respiratory distress may occur and re intubation may be necessary
* *ETT leak test prior to extubation (less than 15% of expired Vt b/w inflated and deflated cuff associated with extubation failure)
* *delay extubation until edema subsides (may be indicated if long ST case or difficult intubation)
31
what are intraoperative fluid considerations with ST?
- periorbital edema greater in pt. receiving LR than with colloid fluids
- fluid restrictions resulted in less operative complications
- fluid kept to less than 2000 ml of crystalloid: reduction in urine contamination with prostatectomies; minimize facial, pharyngeal, laryngeal, periorbital edema
32
what are anesthesia considerations for robotic surgery?
- insert lines, monitors, and protective equipment prior to draping
- brace torso with body fitting bean bag or egg crate to prevent sliding (not shoulder brace or hard mold)
- neuro consult if pre existing intracranial pathology
- ask surgeon for lesser degree of trendelenburg for a shorter duration (increased venous outflow from head)
- low lithotomy positioning
- ophthalmology consult if pre existing intraocular pathology
- use PCV
- control ETCO2 to lower limit of normal
33
what increases risk of higher IOP
- DM
- HTN
- CAD
- elderly
- longer duration of ST
- higher ETCO2
34
what should be suggested if significant facial or conjunctiva edema is noted?
supine position for 5 minutes for each hour of ST
| ex: 3 hrs. of ST and failed leak test, supine (high fowlers) for 15 min
35
what can help determine the degree of airway edema?
leak test
