Laparoscopic Anesthesia Flashcards
advantages of laparoscopic procedures (7)
- less tissue trauma
- reduced post-op pain
- shorter hospital stays
- more rapid return to normal activities
- significant cost savings
- less potential for post-op complications (ex. development of an ileus)
- improved cosmetic results
what two things have improved the safety of laparoscopic procedures dramatically?
*Nagelhout
- open entry trocar
- videoscopic imaging
what are the three main challenges associated with laparoscopic procedures?
*Nagelhout
- pneumoperitoneum
- positioning
- increasingly critical patients
indications for laparoscopic procedures
*huge list Iām never gonna memorize
- cholecystectomy
- appendectomy
- fundoplication
- inguinal hernia repair
- gynecologic procedures (tubal ligation, myomectomy, assisted hysterectomy, oophorectomy, lysis of adhesions, removal of ectopic pregnancies, tubal repair, diagnositc procedures, ovarian cystectomy)
- colon resection
- splenectomy
- nephrectomy
- liver biopsy
- diastasis repair
- bariatric surgeries
- undescended testicles
- prostatectomy
- cystectomy
- robotic procedures
absolute contraindications for laparoscopic procedures (6)
- bowel obstruction
- ileus
- peritonitis
- intraperitoneal hemorrhage
- diaphragmatic hernia
- severe cardiopulmonary disease/CHF
relative contraindications for laparoscopic procedure (8)
- extremes of weight
- inflammatory bowel disease
- presence of large abdominal masses
- advanced intra-uterine pregnancy
- increased intracranial pressures
- VP shunts
- coagulopathy
- previous abdominal surgeries with adhesions
laparoscopic splenectomies are often at high risk for what intra-op complication?
bleeding
what allows for safe insertion of the Veress needle through the umbilicus in the first trimester?
uterus is still low in the pelvis
at what week gestation does the uterus begin to interfere with visualization during laparoscopic procedures?
23 weeks
what maternal value must be monitored very closely in pregnant mothers during laparoscopic procedures?
- PaCO2
- maintain slightly alkalotic - CO2 ~ 30 mmHg
what position should be used for pregnant women undergoing laparoscopic procedures if > 16 weeks ?
30 degree left-uterine displacement
intraperitoneal pressures should be kept less than what in pregnant women during laparoscopic procedures?
- 12 mmHg
- make sure to remind circulator and/or surgeon to keep pressures low
what non-maternal monitoring should be done for pregnant mothers undergoing a laparoscopic procedure?
continuous fetal heart rate - via transvaginal ultrasound
ouch
what are the four potential causes of major physiologic changes during laparoscopy?
- creation of the pneumoperitoneum
- potential for systemic absorption of carbon dioxide
- initial Trendelenburg position
- reverse Trendelenburg position
what is the purpose of a pneumoperitoneum?
to create an environment that allows for the surgeon to see all intra-abdominal structures and successfully manipulate all of the instruments required for that procedure
what is a pneumoperitoneum?
insufflation of the peritoneal cavity with CO2 (or air, nitrous oxide, helium, oxygen)
what are the characteristics of the ideal gas to use for a pneumoperitoneum?
- Nagelhout
- colorlessness
- nonflammable in the presence of electrocautery
- physiologic inertness
- excretion via pulmonary route
pros for the use of CO2 for pneumoperitoneum
- nontoxic *
- non-flammable *
- doesnāt support combustion
- blood solubility enhances tissue diffusion, decreasing risk of air emboli
- less hemodynamic effects vs other gases *
- easy to access
*Nagelhout
cons for the use of CO2 for pneumoperitoneum
- more pain due to diaphragmatic irritation
- hypercarbia, respiratory acidosis
- cardiac dysrhythmias
why are helium and argon not used for pneumoperitoneum?
they caused greater hemodynamic depression if embolized into venous vasculature and caused death at much smaller volumes
why must extreme caution be used to make sure that CO2 tank is actually CO2?
- if the tank is > 7% CO2 it has the same pin index as oxygen
- if using oxygen there is the potential for combustion
physiologic changes from a pneumoperitoneum result from what two things? (big picture)
*Nagelhout
- direct mechanical pressure
- stimulation of intrinsic neurocirculatory responses
advantage of pneumoperitoneum for laparoscopic procedures
separates the abdominal wall from the contents of the peritoneal cavity to optimize visualization and access
disadvantages of pneumoperitoneum for laparoscopic procedures
- limits surgeonās freedom of movement
- limits choice of instruments
- involves risk of significant complications related to the use of CO2
procedure for creating a pneumoperitoneum - closed procedure method
(kinda long, feel free to break it up)
- inject local anesthetic into umbilical area
- insert Veress needle via anesthetized area into peritoneal cavity - verify placement
- insufflate the cavity with CO2 at a pressure less than 19 mm Hg (3 L)
- once distended, insufflator placed in automatic mode to maintain pneumoperitoneum at 12 mm Hg
- trocar then inserted blindly or under direct visualization (*Nagelhout)
an intra-abdominal pressure of less than what indicates correct placement of an umbilically placed Veress needle?
*Nagelhout
10 mmHg or less
what are intra-abdominal pressures maintained at during a laparoscopic procedure?
12-15 mmHg
at what time during a laparoscopic procedure is the patient at the highest risk for serious complications?
- insertion of Veress needle/trocars
- abdominal insufflation
what pressures are used during a retroperitoneoscopic adrenalectomy?
15-20 mmHg
what is an open procedure for creating a pneumoperitoneum?
what are the benefits of this method?
*Nagelhout
- surgeon creates a 1-2.5 mm vertical incision that allows him to directly separate the abdominal wall from the underlying tissues
- minimizes risk of damage to the bowel and vasculature
percentage of injuries that occur during entry and insertion of trocars?
percentage of injuries that are not diagnosed intra-op?
- > 50% occur during entry
- 30-50% not diagnosed intra-op
what can cause massive hemorrhage during the procedure for creating a pneumoperitoneum?
- penetration of vessels
- rupture of the spleen with stretching of pre-existing splenic adhesions
what method is used to assess for urinary structure damage if injury is suspected/likely?
- urinary catheterization and instilling methylene blue
- checking for blood in catheter
what is one way WE can help to prevent organ damage during trocar insertion?
turn off vent/place in bag mode during trocar insertion to avoid organ displacement during inspiration
what can we do to help decrease some amount of abdominal pressure and also at the same time probs decrease some aspiration risk?
- insert OG salem sump and suction/decompress stomach
- can leave in until the end of case
risk factors for injury during laparoscopic procedures (7)
- body habitus
- anatomic anomalies
- prior surgeries
- surgical skill
- degree of abdominal elevation during trocar placement
- patient position
- volume of gas insufflation
what factors should alert the team to a potential vascular injury?
*Nagelhout
- blood on aspiration of Veress needle
- free intraperitoneal blood
- unexplained hypotension and tachycardia
which entry technique is associated with a lower incidence of unrecognized vascular and visceral injury?
*Nagelhout
open entry
what is the benefit of placement of the primary trocar under high pressure (25 mmHg)?
*Nagelhout
high pressure creates the safest distance between the anterior abdominal wall and underlying abdominal contents and minimizes injury from trocar insertion
what can cause subcutaneous emphysema?
~ not the long chart
- improper placement of the needle between fascial planes in the muscle
- high intra-abdominal pressures*
- movement of gas through defects in the peritoneum*
(*Nagelhout)
subcutaneous emphysema has been associated with what negative outcomes?
- airway issues
- severe hypercarbia*
- decreased chest compliance*
- hemodynamic instability*
(*Nagelhout)
how can we assess for subcutaneous emphysema in the airway?
- leak test
- if present, consider leaving the patient intubated until reabsorbed
the magnitude of the patientās physiologic response to the pneumoperitoneum depends on? (8)
- intraabdominal pressure attained
- volume of CO2 absorbed
- position
- age/co-morbidities
- intravascular volume
- ventilatory technique
- surgical conditions / time
- anesthetic agents used
effect of pneumoperitoneum on SVR?
cause of early change?
cause of late change?
- increased SVR
- increase initially due to increased levels of vasopressin
- later, increase is due to increased catecholamines (more related to 20 torr v 10 torr)
*increase SVR whether 5 mmHg or 40 mmHg
effect of pneumoperitoneum on MAP?
cause?
- increased MAP
- due to catecholamines
*increase MAP whether 5 mmHg or 40 mmHg
effect of pneumoperitoneum on HR? (at normal pressures)
cause?
- increased HR
- due to catecholamines
at what pressures is there a difference in the effect of pneumoperitoneum on HR?
- 5-20 mmHg: HR is increased
- 40 mmHg: HR is decreased
effects of pneumoperitoneum on CVP?
causes?
- initial increase in CVP due to squeeze of spleen and liver (blood reservoirs) and redistribution of abdominal blood volume
- later decreased due to reduction in venous return, but filling pressures increase
what causes a bigger effect on central pressures, position or pneumoperitoneum?
patient position
T/F: the effect on HR, MAP, and SVR only occur for a short time after abdominal insufflation
*Nagelhout
false - lasts for the duration of the insufflation
effect of pneumoperitoneum on cardiac index?
cause?
- decrease - 50% of baseline, proportional to the intra-abdominal pressure achieved
- due to decrease venous return from pneumoperitoneum and reverse trendelenburg reducing stroke volume
what can be done to reduce the amount of decrease in cardiac output from pneumoperitoneum?
- adequate fluid load (normovolemia)
- compression stockings/SCDs
- changes in patient position
~decreases to only 20% reduction in cardiac output vs 50%
what is our #1 job on insufflation?
watch EKG!
vagal stimulation with insufflation can cause bradycardia that can lead to asystole
high pressure insufflation can cause what EKG change?
prolonged QT
what are the two main causes of bradycardia in laparoscopic procedures?
- high abdominal pressures
- rapid insufflation
if bradycardia is seen on insufflation, what should be done?
- tell surgeon to relieve pressure - should automatically fix
- if it doesnāt resolve with pressure relief give atropine
GFR and UOP effects seen from pneumoperitoneum at varying pressures
- 5 mmHg - no change
- 10 mmHg - decreased
- 20 mmHg and higher - significant decrease
venous return effects at different pressures
- 5 mmHg - no change or decreased
- 10 mmHg - no change or increased
- 20 mmHg - increased or decreased
- 40 mmHg - decreased
cardiac output effects at different pressures
- 5 mmHg - no change or decreased
- 10 mmHg - no change or increased
- 20 mmHg - no change or decreased
- 40 mmHg - decreased
what pneumoperitoneum pressures can show an increase in cardiac output?
10 mmHg can show no change or an increase
all other pressures are no change or are decreased
what pneumoperitoneal pressures start to potentially cause an increase in CO2?
10 mmHg and higher
what pneumoperitoneal pressures start to potentially cause a decrease in pH?
10 mmHg and higher
what causes the initial increased filling pressures with a pneumoperitoneum?
does this correlate with an increase in volume in the heart?
- compression of abdominal venous beds which pushes blood back into central circulation
- pressure numbers are increased, but volume is not
effects of pneumoperitoneum on cerebral blood flow and ICP?
both are increased
does hyper/hypoventilation have an effect on the pneumoperitoneumās effect on cerebral blood flow and ICP?
- hyperventilation does not effect
- hypoventilation makes it worse
an abdominal pressure of ~16 mmHg and tredelenburg causes how much of an increase in ICP?
150%
what effect does abdominal insufflation have on CSF?
- reduced reabsorption
- due to increased IVC pressure and impaired venous drainage of the lumbar venous plexus
other than direct compression of the renal vasculature due to abdominal pressures, what else can cause further decrease in renal blood flow?
sympathetic stimulation causes ADH and renin release ā> more vasoconstriction to kidneys
effect of pneumoperitoneum on kidneys, liver, and splanchnic blood flow?
- decreased
- bigger effects seen with pressures > ~14 mmHg
what three conditions place the patient at an increased risk of decompensation from abdominal insufflation?
*Nagelhout
- increased metabolic rate (sepsis)
- large dead space
- decreased cardiac output
what places a COPD patient at an increased risk of post-op complications after laparoscopic surgery?
higher level of CO2 retention and respiratory acidosis
what device might be useful for monitoring CO2 levels during insufflation/why?
what patient population might have a huge benefit from this?
*Nagelhout
- transcutaneous CO2 monitor (PTCO2)
- ETCO2 may underestimate PaCO2
- COPD patients would have big benefit from PTCO2 monitor
effect of pneumoperitoneum on pulmonary compliance
- decreased due to diaphragm shifting upwards
- increased peak pressures
effect of pneumoperitoneum on lung volumes?
- decreased vital vapacity
- decreased FRC