anesthetic management of robotic procedures in steep trendelenburg Flashcards
what are advantages of robotic surgery
- 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
what are advantages of robotic surgery
- 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
what are disadvantages of robotic procedures
- 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
what is the triple threat?
altered physiology with 3 positions:
- lithotomy
- abdominal insufflation
- steep trendelenburg
what is steep trendelenburg?
> 30 degrees, max 45 degrees tilt head down
why is steep trendelenburg used in robotic procedures?
-maximal surgical exposure and optimal visualization
what position is prostate, colon, and GYN surgeries usually performed in?
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
what are the effects of steep trendelenburg on the pulmonary system?
- 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%)
what insufflation pressures are recommended?
how does the pneumoperitoneum (abdomen insufflation) affect the pulmonary system
- 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
what has been shown to improve oxygenation after prolonged pneumonperitoneum?
PEEP of 5 cmH2O
how can the pt. in ST be ventilated?
- 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
what caution needs to be taken with PCV?
- use volume control
- inadequate Vt if PC setting is too low
- excessive Vt can lead to volutrauma when pneumoperitoneum is released
what are intraocular effects of ST?
- 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
why is the CV system not the biggest concern with ST?
body often compensates for changes
what should be suspected with pneumoperitoneum if sudden CV collapse with capnograph changes?
venous CO2 gas embolism
-sudden drop in BP and capnograph flattens out
what increases emboli risk with pneumoperitoneum?
- CO2 > 50 mmHg
- six or more ports
- operative time > 200 minutes
- older pt.
when is venous emboli more common with pneumoperitoneum?
- initial insufflation
- dissection of deep venous tissue
what can CO2 buildup after pneumonperitoneum cause?
- 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
what are cerebrovascular effects of robotic surgery?
- elevated PaCO2: absorption of CO2 leads to cerebral vasodilation and increased cerebral blood flow
- adds to venous congestion
what are cerebrovascular effects of pneumonperitoneum with robotic surgery?
abdominal compression causes reduced venous outflow
*adds to venous congestion
what are the cerebrovascular effects of ST?
- gravitational forces cause a reduction in venous return
- cranial drainage reduced
- CT scans have shown cerebral edema
what are intracranial effects of both trendelenburg and pneumonperitoneum?
- 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
what helps preserve cerebrovascular homeostasis?
normocarbia
when are cerebral ischemia risks elevated?
subjects with cerebral vascular disease or increased ICP
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
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
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
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
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)
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
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
what increases risk of higher IOP
- DM
- HTN
- CAD
- elderly
- longer duration of ST
- higher ETCO2
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
what can help determine the degree of airway edema?
leak test
