Anesthesia for Abdominal General Surgery Flashcards
Common GI Associated Problems
N/V Ascites Pain GERD Obesity Cancer Anemia Fluid & Electrolyte Disorders
General Anesthesia for General Surgery
Advantages
allows paralysis, more safely allows positioning extremes, more reliable, lower failure rate
General Anesthesia for General Surgery
Disadvantages
increased stress response, known full stomach, increased risk for aspiration, more postoperative nausea and sedation
Regional Anesthesia for General Surgery
Advantages
requires lower insufflation pressures, patient breaths spontaneously, decreased stress response, faster recovery period
Regional Anesthesia for General Surgery
Disadvantages
occasional failure, sympathectomy
MAC/IV sedation for General Surgery
Combined with local anesthesia, patient breathes spontaneously, patient comfort level
Considerations for Anesthetic Management
choice of anesthetic, routine monitors, foley catheter, cuffed ETT, pneumoperitoneum, evacuation of gastric contents, positioning, smooth emergence/extubation, antiemetics, and pain management
Anesthesia for Laparoscopic Surgery
used for diagnostic & surgical intervention
insufflation of abdomen (CO2)
view of abdominal contents through small incisions
use of small instruments through trocars
camera projects images on monitor screen
minimally invasive surgery
Anesthesia for Laparoscopic Surgery
Advantages
lower pain scores & opioid requirement
earlier ambulation & return to normal activities
lower incidence of post-op ileus
usually faster recovery, shorter hospital stay
reduced post-op pulm/diaphragmatic dysfunction
less stress response & less wound complications
lower cost
Anesthesia for Laparoscopic Surgery
Disadvantages
impaired visualization expensive equipment requires specific surgical skill limited ROM altered depth perception no tactile sensation increased PONV referred pain
Laparoscopy relative contraindications
Inc. ICP, hypovolemia, V/P shunt, severe CV or respiratory disease, and dense adhesions
Surgical Exposure - CO2 Pneumoperitoneum
insufflation of the abdomen with CO2, more soluble in blood than air, helium and oxygen or nitrous oxide
easily absorbed by the tissues with rapid elimination (via respiration)
non-combustible, colorless, odorless, and inexpensive
Effects of CO2 Insufflation
HTN, Tachy (sympathetic stimulation)
hypotension (impaired venous return)
arrhythmia, bradycardia (vagal stimulation)
reduced FRC, compliance, increased ventilatory pressures, barotrauma, and atelectasis
reduced renal perfusion, activation of RAAS, increased ADH
increased intra-abdominal pressures, risk of gastric regurg, splanchnic ischemia, CO2 embolus, extra peritoneal spread of CO2
Physiologic Effects of Pneumoperitoneum
increased: PaCO2, ETCO2, PAP, MAP, SVR, HR, CVP, IAP, ICP, Vd (deadspace), risk of regurg/aspiration
decreased: cardiopulm function, CO, VR, FRC, VC, and renal function
Clinical Management of Physiological Pulmonary Changes
position changes (decrease degree of trendelenburg) modify ventilatory support (pressure control) use PEEP w/ caution consider increasing volatile & bronchodilators
Clinical Management of Physiological Cardiovascular Changes
slow, gradual abdominal insufflations
vent abdomen if IAP>20mmHg
evaluate intravascular volume (IVF bolus)
consider treatment for preexisiting cardiac dysfunction
Clinical Management of Physiological Renal/Hepatic Changes
closely monitor hourly UOP
administer IVF boluses
consider diuretics
maintain IAP <15 mmHg
Clinical Management of Physiological Cerebral Blood Flow Changes
Decrease degree trendelenburg (adjust head up)
vent abdomen if IAP >20mmHg
General Anesthesia for Laparoscopic Surgery
GA w/ cuffed ETT & controlled ventilation
increased min ventilation & PIP often required
adjust RR, Vt (6-8ml/kg), PEEP (5-10 cmH20)
Goals: ETCO2 35 mmHg, PIP low 30’s cmH20
Regional Anesthesia for Laparoscopic Surgery
Regional has been used but risky
need high block T4-5 (SNS denervation) more difficult to compensate for CV, ventilatory changes, shoulder & distention pain incompletely alleviated
Anesthesia for Laparoscopic Surgery
Intra-abdominal pressure limit of <15mmHg is best to avoid CV compromise
ASA 3-4 and/or abnormal gradient PaCO2:ETCO2 invasive monitors (blood gas and BP measurements)
General Endotracheal Tube Anesthesia vs. LMA
ETT: secure airway (aspiration protection) and control of ventilation ProSeal LMA (controversial): spontaneous ventilation, lower incidence of sore throat, lower pain scores, less analgesic medications, less PONV. Unable to secure airway (aspiration risk), control ventilation, & administer muscle relaxation
Anesthesia for Laparoscopic Surgery: Positioning
Prevent nerve injury - common peroneal nerve (lithotomy) & brachial plexus (shoulder braces)
Tilt not to exceed 15-20 degrees
Make changes slowly, recheck ETT position after every position change, consider less aggressive fluid replacement in head down position (edema)
Anesthesia for Laparoscopic Surgery: GA Maintenance
balanced techniques appropriate using volatile agent, opioids, or TIVA (no N20)
consider propofol TIVA if PONV
continue muscle relaxation, careful monitoring of pulmonary and hemodynamic status
watch for endobronchial intubation during position changes (head up or down)
Conversion to open procedure
supine position, new fluid plan (3rd space losses will increase), new pain management plan (increase opioid requirements), new ventilator settings (may need to increase RR and increase Vt
Monitoring for Intraop Complications
Vascular injury: trocar insertion/veress needle- aorta, ICV, iliac vessels, cystic/hepatic arteries, retroperitoneal hematoma
GI: bowel, liver, spleen, mesenteric
Cardiac: dysrhythmias- hypercarbia, increased vagal tone with peritoneal traction, BP changes
SQ Emphysema: extra peritoneal insufflation
Capnothorax/Capnomediastinum/Capnopericardium: diaphragm defect, pleural tear, bullae rupture, high degree of suspicion can be lifesaving
CO2 Embolism: direct needle placement in vessel, gas insufflation into abdominal organ
Gas Embolism Patho
depends on size of bubbles and rate of entrainment
vapor lock in vena cava and RA
obstruction to venous return
actue RV hypertension = paradoxical embolism
circulatory collapse
Gas Embolism Diagnostic Tools
TEE, swanganz catheter, precordial dopplers
real world: pulse ox, sudden ETCO2 decrease, aspiration of gas from CVP, hypotension, bronchospasm, and increased PIP
Gas Embolism Treatment
stop insufflation and desufflate
positioning (steep trendelenberg, left lateral decubitus)
D/C N20 and give 100% FiO2
hyperventilate, place CVP, CPR, and consider CPB
Sub Q Emphysema
accidental insufflation of extraperitoneum
increases in PaCO2 after plateau has been reached
not a contraindication for extubation
can track to thorax and mediastinum
(worry when airway becomes deviated)
Common Laparoscopic GI Procedures
Cholecystectomy: removal diseased gall bladder (cholecystitis, cholelithiasis, cancer)
Herniorrhaphy: defect in muscles of the abdominal wall (inguinal, umbilical, incisional, abdominal, femoral, diaphragmatic)
Appendectomy: most common acute surgical procedure of the abdomen. Etiology: obstruction with inflammation by lymphoid tissue or fecal matter
Cholecystectomy
laparoscopic venous return (rate of conversion 5-10%)
sphincter of oddi spasm
Risk factors for conversion to open:
actue cholecystitis w/ thickened gallbladder wall, previous upper abdominal surgery (adhesions), males, advanced age, obesity, bleeding, bile duct injury
Herniorrhaphy
outpatient, elective surgery
open or laparoscopic
potential for incarceration if not reduced (urgent surgery)
strangulated: emergency surgery with GA, can lead to necrotic bowel requiring bowel resection. higher morbidity & mortality
Appendectomy
low mortality 1% (2% if perforated) incidence: 6% of population perforation: septic shock, peritonitis F&E deficits from N/V aspiration precautions, ABX, avoid Reglan w/ obstruction skeletal muscle relaxant usual with RSI
Anesthesia for Laparoscopic Surgery: GA Emergence & Postop Considerations
procedures associated with intra-abdominal, incisional, and shoulder pain (irritation of diaphragm and/or visceral pain from biliary spasm)
opioids + NSAIDS + acetaminophen + decadron + local anesthetic infiltration (incisional and intraperitoneal)
PONV 40-75%
Herniorrhaphy
avoid strain, general, local or regional (T8) anesthesia
discuss plan w/ surgeon regarding pt cough, EBL 50 mL, postop pain 4-6, LA infiltraton of ilioinguinal & iliohypogastric nerves, bradycardia results from peritoneal retraction
