GI Anesthesia Flashcards
Cause of right mainstem during laparoscopy
Displacement of the diaphragm into the thorax caused by abdominal insufflation (trendelenburg)
Trendelengburg
Head down
Reverse trendelenburg
Head up
Impacts of severe hypercarbia
Myocardial depression
Dysrhythmias
Systemic vasodilation
Impact on the cardiopulmonary system from hypercarbia
Hypercarbia induced pulmonary vasoconstriction acutely elevated right ventricular afterload
Why do obese patients tolerate insufflation better?
Intrinsically elevated IAP
Problems with COPD and pneumoperitoneum
Hypercarbia may be refractory to hyperventilation
Increased alveolar physiologic space in these patients leads to a wide PaCO2-ETCO2 difference=monitoring may underestimate the actual CO2
Renal function and pneumoperitoneum
It’s reduced! Surprise!
However… reduction in renal perfusion induces vasopressin release which results in reduced free water excretion and is associated with an increase in abdominal cavity pressure
Explain the debate about high O2 concentrations
High concentration PROs: reduced PONC, improved wound healing, and optimal VQ matching
Cons: alveolar nitrogen washout and subsequent absorption ateletasis, reactive o2 species cause cellular injury, and pulmonary oxygen toxicity
Fluid management
Hard to pinpoint
But in healthy patients increased intraoperative fluid loading is associated with improved postoperative pulmonary function, exercise capacity, and overall well being
Main complication in laparoscopy
Needle/trocar insertion
Be prepared for severe hemorrhage but routine preop t/s is not necessary
Define subcutaneous emphysema
Introduction of CO2 gas into subcutaneous, preperitonneal, or retroperitoneal tissue leading to trapped gas pockets
Risk factors and treatment of subQ emphysema
Longer than 3.5 hours
IAP>15mmhg
# surgical ports
ETCO2> 50mmhg
-hyperventilation, deflation
Capnothorax, define and treat
CO2 accumulation in the pleural space
Desufflation, hyperventilation
Severe: needle decompression
Laparoscopy disadvantages
Pneumoperitoneum- CO2 related, stress response
Visceral injury/hemorrhage
Increased surgery time
Position injuries
Blood loss ambiguous
Why CO2 in pneumoperitoneum?
Non-toxic
Non-flammable
Minimal air embolus
Neurohormonal effects of CO2
Increased levels of catecholamines
-dopamine, epinephrine, norepinephrine
Increased renin
Increased vasopressin
=Increased SVR
Cause of post op shoulder pain in pneumoperitoneum
Carbonic acid is a peritoneal irritant and causes referred pain
Metabolic derangement created by CO2
Respiratory Acidosis
How does pneumoperitoneum affect venous return?
Increases
How does pneumoperitoneum affect stroke volume?
Decreases
How does reverse trendelenburg affect preload?
Increases
Describe pneumoperitoneum impact on the respiratory system?
Diaphragm displaced
Carina shifted cephalad
Lung volumes decreased
Hyperventilation to normalize CO2
Splanchnic and pneumoperitoneum
Decreased blood flow via external compression and systemic vasoconstriction
Mesenteric impact of pneumoperitoneum
Ischemia from insufflation pressures of 10-14mmhg
Long periods of insufflation will do what to the renal system?
Oliguria -decreased pressure
Anesthesia preop management for laparoscopy
Aspiration prophylaxis
Fluid loading
Intraop anesthetic management for laparoscopy
GETA
PEEP
Recruitment maneuvers
Muscle relaxation
Avoid N2O…
N2O and the bowel
30x more soluble in the blood than N2
Diffuses rapidly into gas cavities
May lead to:
distention
ischemia
difficult surgical exposure
PONV
Why don’t we use N20 for insufflation?
Combustible
What does bowel perforation liberate?
Methane/hydrogen
What are we confirming with position changes in laparoscopy?
ETT -mainstem
PONV in Laparoscopy
As high as 72%
Leads to: wound dehiscence, aspiration, hospital admission
TIVA decreases incidence to 10%
How to treat referred shoulder pain?
NSAIDs (ketorolac)
What interesting thing are we using for pain in laparoscopy?
Lidocaine
Reduces post op pain, PONV, early return of GI function
Laparoscopy complications
Visceral/vessels punctures
Urinary injury
Subcutaneous emphysema
Gas embolism- microemboli VERY common
Gas embolism signs
Decreasing End tidal
Cardiovascular changes- tachycardia, arrhythmias, hypotension, CV collapse
What decreases in gas embolism?
PCO2
Oxygen saturation
Blood pressure
What increases in gas embolism?
End tidal nitrogen
PA pressures
Dysrhythmias
Cyanosis
Hypoxia
“Mill-wheel”murmur
MANAGING Gas embolus
Stop insufflation
Eliminate N20
Flood field
Left lateral decubitus
Aspirate with CVC
Support
Durant maneuver
Left lateral decubitus
What do we ALWAYS do with concerning changes in pneumoperitoneum
Deflate the Michelin man
Until problem is identified
Barrett’s esophagus
Pre-malignant changes from chronic reflux
Achalasia
Dilation of distal esophagus w/frequent regurgitation due to impaired lower esophageal sphincter relaxation
Hiatal hernia
Herniation of abdominal contents through esophageal hiatus into the mediastinum
-associated with GERD and esophagitis
Type 1 hiatal hernia
“Sliding type”- upper stomach only moves through the enlarged esophageal hiatus
Type II hiatus
Paraesophageal type- all or part of the stomach moves into the thorax
Type III hiatus
MIXED type of I and II
Type IV hiatus
Most severe, other organs such as bowel may be contained in the hernial sac
UES
Upper esophageal sphincter
-pharyngoesophageal junction
Tonic contraction 15-60 cmh20
Seals upper esophagus from hypopharynx
LES
Lower esophageal sphincter
Border of esophagus and stomach
Resting tone 15-20 cm h20
Barrier pressure
LES minus gastric pressure
Managing esophageal disorders (medical)
Antacids
Mucosal protection agents
H2 blockers
PPIs
Prokintetics
Anesthetic management of esophageal disease
Aspiration prophylaxis
RSI w/cricoid or awake fiber optic
Nissan fundoplication
Intervention for GERD or hiatal hernia
-usually laparoscopic
GETA and muscle relaxation
PONV prophylaxis!!!
When are we paying attention in Nissan fundoplicaiton?
During placement of esophageal bougies (dilators)
Cholecystitis
Obstruction or infection
90-95% due to gallstones
Labs: increased-bilirubin, alkaline phosphatase, amylase
Leukocytes is and fever
Murphys sign
Inspiratory efforts is painful
Indicative of Cholecystitis
Anesthetic management of cholecystectomy
Rehydrate
GETA
OGT for decompression
Glucagon admin during cholangiogram
Postop:shoulder pain-abd pain may last for years
Glucagon dosing
<2mg otherwise nausea
Know anatomy of the small intestine!
Starts with Pyloric sphincter
Jejunum
Ileum
Ends with ileocecal valve
General anesthetic considerations in large and small bowel surgeries
Aspiration
Hypovolemia
PH/electrolyte imbalance
Fluid shifts
Avoid N20
Pain management
Crohn’s disease
Commonly impacts distal ileum and proximal large colon
-advanced disease=malabsorption and protein loss-anemia is common
Fistulas common
Medical management of crohns
Sulfasalazine
Glucocorticoid
Immunotherapy
Immunomodulators
Anesthetic considerations for crohns bowel resections
Stress dose steroids for patients on chronic glucocorticoids
Fluid electrolytes anemia
Pain-consider epidural
Ulcerative colitis
Inflammatory disease causes ulceration of colonic mucosa (extends proximally from rectum
-treat similarly to crohns
Difference between crohns and ulcerative colitis
UC surgical intervention is often curative with large bowel resection and ileostomy
Pathophys of excess serotonin
Vasoconstriction
Increased intestinal tone
Water and electrolyte imbalance-diarrhea
Hypoproteinemia
Hyperglycemia
Plaque formation
Carcinoid syndrome
Slow growing SI tumors that arise form enterochromaffin cells in GI tract
Release vasoactive substances-serotonin/kallikrein/histamine
If limited to the GI tract the liver can process these substances
Carcinoid syndrome symptoms
Cutaneous flushing
Bronchoconstriction
Hypotension
Diarrhea
Heart disease
What do we clarify with endocrinologist in carcinoid syndrome
Octreotide administration
Anesthetic management of carcinoid syndrome
Avoid provoking release of vasoactive substances!
-avoid: ketamine, ephedrine, epi, norepi
-morphine, succinylcholine
Treating crisis: octreotide: 150-200mcg Q6-8hrs
Phenylepherine and volume
Treating bronchospasm in carcinoid syndrome
Octreotide
How much pressure causes injury?
20-30 mmhg
Explain shoulder pain in laparoscopy
CO2 accumulation (ie carbonic acid buildup) irritates the phrenic nerve
Henrys law
Henry’s law is a gas law that states that the amount of dissolved gas in a liquid is directly proportional at equilibrium to its partial pressure above the liquid.
What are we looking for during inflation?
Baroreceptor response
Bradycardia and cardiac arrest
-have glyco on hand
Effects of hypercapnia on the lungs
Pulmonary vasoconstriction leading to increased right ventricular afterload
How does insufflation impact map and co?
Map increases
Co decreases
Stats on trocar insertion injury
They occur in 1% of surgeries
And
Cause 50% of injuries…
Biggest determinant of esophageal reflux
Barrier pressure
In gastric cases what do you not pull out at the end of the case?
Nasogastric tube
What does glucagon do?
Spasmolysis at sphincter of Oddi
Carcinoid triad of symptoms
Diarrhea
Flushing
Cardiac-(heart disease)
Diagnosing carcinoid syndrome
Elevated levels of serotonin metabolites in the urine
Histamine releasing drugs we avoid in carcinoid syndrome
Morphine
Atracurium
Big consideration in pancreaticoduocenctomy
(Whipple)
Put in a-line/cvc
You’re gonna give blood
Carcinoid crisis dosing
Treat crisis with octreotide: 150mcg-200mcg Q 6-8hrs during AND for
24-48 hours prior to surgery.
