Anesthesia for Abdominal General Surgery Flashcards by Emily Toth

Common GI Associated Problems

N/V
Ascites
Pain 
GERD
Obesity 
Cancer
Anemia
Fluid & Electrolyte Disorders

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General Anesthesia for General Surgery

Advantages

allows paralysis, more safely allows positioning extremes, more reliable, lower failure rate

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General Anesthesia for General Surgery

Disadvantages

increased stress response, known full stomach, increased risk for aspiration, more postoperative nausea and sedation

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Regional Anesthesia for General Surgery

Advantages

requires lower insufflation pressures, patient breaths spontaneously, decreased stress response, faster recovery period

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Regional Anesthesia for General Surgery

Disadvantages

occasional failure, sympathectomy

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MAC/IV sedation for General Surgery

Combined with local anesthesia, patient breathes spontaneously, patient comfort level

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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

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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

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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

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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

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Laparoscopy relative contraindications

Inc. ICP, hypovolemia, V/P shunt, severe CV or respiratory disease, and dense adhesions

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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

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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

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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

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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

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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