Anesthesia for ambulatory and lap sx

Question 1

What is the incentive for hospitals to emphasize ambulatory anesthesia?

Answer 1

Hospitals often times receive the same reimbursement for short stay versus outpatient.

Question 2

What is ambulatory surgery? short stay surgery?

Answer 2

• Ambulatory surgery is when patients are admitted for operation and discharged on the same calendar day.
• Short stay surgery includes an over-night admission because:
  
  • 1) sx occurred too late
  • 2) lack of social support
  • 3) co-morbid conditions
  • 4) physiologic derangement associated with sx

Question 3

What characteristics are needed for high-quality same day surgery?

Answer 3

reduced tissue trauma,

enhanced recovery because of lower incidence fo complications

improved patient education and analgesia

appropriate postop supprot

Question 4

What are the four basic design schemes for ambulatory surgery?

Answer 4

• Hospital integrated
• hospital self-contained
• freestanding
• office based

Question 5

What is a hospital integrated ambulatoyr sx design?

Answer 5

• ambulatory sx patients managed in same facility as inpatients
• outpatients may have separate preop and second-stage recovery areas
• downside- possibility cases may be bumped for emergency inpatient procedure
  
  • this increases cost and decreases efficiency

Question 6

What is hospital based/self contained ambulatory sx facility?

Answer 6

• separate ambulatory surgical facility within a hospital which handles only outpatients
• own admin, check in, administration, OR, PACU
• Advantage- cases won’t be bumped for emergency cases
• disadvantage- duplication of services and less flexibility as inpatient and SDS cases fluctuate.

Question 7

What is freestanding ambulatory sx design?

Answer 7

• surgical and diagnostic facilities associated with hospitals but housed in separate building that share no space/patient care functions
• more restrictive to type of patient that can be done there
• con- if unplanned admission required, need to transport patient to another faciliaty

Question 8

What is office based ambulatory surgery design?

Answer 8

• Operating or diagnostic suites that managed with physicians’ offices for the convenience of patient and HCP
• regulation not always the same level as other designs
• significant limitations regarding equipment, staffing, and environmental limitations that may make it more difficult to manage adverse events

Question 9

Who sets quality and safety standard for ambulatory surgical centers?

Answer 9

• Governmental regulation and licensing
• accreditation
  
  • Accreditation Association for ambulatory health care (AAAHC)
  • American Association for Accreditation of Ambulatoyr Surgery Facilities (AAASF)
  • The Joint Comission (hospital based facilities)
  • Center for Medicare and Medicaid Services (CMS)
• Professional orgs
  
  • AANA
    
    • standard for office based anesthesia based practice
    • ON CANVAS NEED TO KNOW FOR EXAM
  • ASA

Question 10

According to AANA Office Based Anesthesia position statement, what should providers determine prior to considering an office based practice?

Answer 10

• Are there appropriate resources to manage various level of anesthesia for planned surgical procedures and condition of patient?
• At a minimum CRNA shall determine that there are policies to address:
  
  • patient selection criteria
  • monitoring equipment with backup electrical source
  • adequate number of well-trained personnel to support planned surgery, admin of anesthesia, and patient’s recovery
  • treatment of foreseeable complications
  • accessibility and suitability of emergency drugs and resus equipment
  • patient transfer to other facilities
  • infection control, OSHA requirements
  • preop testing and appropriate consultation
  • ancillary services
  • equipment maintenance
  • response to fire and other catastrophic events
  • recovery and d/c of patients
  • procedures for follow up care
• “Spelled out by restating the AANA professional standards of practice and then adding an application to office practice for each standard.”
  
  • provides checklists:
    
    • minimum elements for providing anesthesia services in the office based practice setting
    • anesthesia equipment and supplies checklist
    • position statement on MH preparedness and treatment

Question 11

Quality of Safety of ambulatory surgery?

Answer 11

• COnsidered very safe despite increased medical and surgical complexity in recent years
• periop mortality 1:11,000
• relatively few absolute contraindications

Question 12

What factors into patient selection criteria and selection of procedures?

Answer 12

• degree of physiologic disturbance
  
  • surgical procedure
    
    • how invasive is the procedure?
    • need minimal postop complications
    • no major fluid shifts
  • physiologic response
    
    • no major blood loss, no need for complex postop care
    • consider the potential for blood loss, pain, PONV
  • pain management (regional is a good option)
    
    • procedures requiring prolonged immobilization and IV opioid therapy are more suitable to 23-hour stay
• huge financial incentive to promote same-day surgery (SDS) over hospital stays since insurance companies pay flat rate for SDS qualifying procedures regardless of LOS
• SDS has expanded due to:
  
  • improved surgical techniques
  • better pain control methods
  • shorter acting anesthestics
  • questioning of conventional assumptions that patients are psychologically and physiologically better off in the hospital (studies show this is not the case)

Question 13

What are some procedures that have been added to 23 hour obs in 9th edition miller?

Answer 13

• Roux en y gastric bypass
• some neurosx procedures
  
  • tumor resection, aneurysm clipping, awake crani for supertentorial tumors

Question 14

Is there a time length to surgery done in ambulatory sx?

Answer 14

• No, used to be 90 min
• Now it’s more important to consider invasiveness of surgery.
  
  • however, pain, emesis delayed discharge and hospital admission rates are higher the longer the surgery

Question 15

Patient characteristics for ambulatory surgery?

Answer 15

• Important to determine if pre-existing condition is likely to cause postoperative complications vs perioperative complications
  
  • ASA III and IV now considered OK if medically stable
• Extremes of age
  
  • <6 months and >85 yo
    
    • adv age is not a contraindication to SDS.
      
      • 2x risk for CV events introp but less pain, PONV, dizziness and lower rates of unaticipated admission
      • study suggest cognitive function better at home
    • must have strong social support
• Co-existing dx
  
  • stable physiologic dx- no dx “label” is contraindicated, consider stability of dx
  • obesity not contraindication.
    
    • again, have difficulty managing case intraop, but postop complications may be better
  • sometimes better to keep pt with chronic conditions on own routine and d/c to home

Question 16

Factors to consider preoperatively to determine if pt is appropriate for amb sx?

Answer 16

1. Sleep apnea status
   
   • mild, mod, or severe
   • what’s the sleep study say?
2. Anatomical and physio abnormalities
   
   • where are they working? upper abd/chest more risk than LE, etc
3. Status of coexisting dx
4. nature of sx
5. type of anesthesia
   
   • local/regional less risky than GA
6. Need for postop opioids
7. pt age
8. adequacy of postop observation
   
   • responsible adult to go home with pt?
9. capabilities of the outpatient facility

Question 17

What factors increase risk for postop admission after SDS?

Answer 17

1. >65 years
2. OR time >120 min
3. CV dx (CAD, PVD, etc)
4. Malignancy
   
   1. enhances pt risk for bleeding
      
      • ​ex- place LMA in pt receiving radiation, blood everywhere
5. HIV
   
   1. meds patient take to manage HIV can predispose patient to complications
6. Regional and general anesthesia

Question 18

What are some relative contraindications to outpatient surgery?

Answer 18

• Uncontrolled systemic dx
  
  • DM, unstable angina, severe asthma, pickwickian (OHS), pain
  • no disease label itself is a c/i, have to consider the individual situation
• Central acting therapies
  
  • MOAI’s and cocaine (routine heavy user of cocaine)
    
    • ​MAOIs such as parglyine and tranylcypromine
    • cocaine has an association with increased risk of intraoperative CV complications including death
  • diet aids like ephedra and alcoholism also increase risk
• Morbid obesity + symptomatic CV or pulm disease
• lack of support at home postop
  
  • cannot drive themselves home
  • live close enough to return to hospital in reasonable amount of time
  • in US expect 24 hours escort, but some countries allow D/C without escort and not seeing an increase in adverse effects as a result
    
    • ​most people don’t have a person stay with them 24 hours

Question 19

Neonate/infant outpatient surgery guidelines?

Answer 19

• < 46 weeks post conceptual age infants born full term (>37 weeks)= 12 hours monitoring
• <60 weeks post conceptual age infants born premature (<37 weeks)= 12 hours monitoring
• still remains controversial but most agree 60 weeks PGA as the cutoff
• caffeine has bene shown to decrease risk for postop apnea in premier babies

Question 20

Preoperative assessment standards?

Answer 20

Same as inpatient

• Identify absolute contraindications to ambulatory surgery
• identify need for optimization
• highlight issues for anesthesiologist or other staff
• provide patient information
• • telephone interview/computerized triage and questionnaire are valuable alternatives and can be just as accurate as physician interview (if not more)*
• • routine blood tests not predictive of complications and ECG abnormalities may not have much addtl significance to a thorough pt history*
• • preop testing had no influence on 30 day unanticipated admission rates*

Question 21

2 major questions to consider when preoping an ambulatory patient? (according to miller)

Answer 21

• Any benefit to this patient being in the hospital overnight after surgery
• Is there anything that needs to be done to enable this patient to be a SDS case?
  
  • better optimize pt, etc

Question 22

Preop fasting guidelines?

Answer 22

• Asa recommends fasting 2 hours clear, 4 hours breast milk, 6 hours non human milk/formula, 6 hours light solid meal, 8 hours heavy meal
• ERAS encourages carb bev 2 hours preop
• new emphasis on limiting NPO times to reduce dehydration, hypoglycemia and PONV
• gum chewing appears to be ok
• fasting intervals safe in gastric volumes in obese pt, children, DM and GERD
• 1/2 life of clear fluids = 10-20 min
• residual volume after 2 hours is less than a patient that fasted twice as long

Question 23

Element of preop eval? Most valuable element?

Answer 23

• Education- reduce patient anxiety
  
  • teach pain control techniques
    
    • teach when block might wear off
• medical history (most valuable)
• physical exam
  
  • recent URI- consider delaying surgery for 6 weeks s/p URI because airflow obstruction has been shown to persis for 6 weeks post URI
  • take complete clinical picture into account- does patient have fever, increased RR, fatigued, etc
• lab testing (minimize!)
• preop specialist consultation

Question 24

Preop preparations? (meds etc)

Answer 24

• Continue current med regimne
  
  • small h2o with meds up to 30 min before
• Non-pharm anxiety contorl
  
  • detailed instructions for day of sx routine
• Pharmacologic anxiety
  
  • midazolam
    
    • may also decrease ponv
    • does not appear to delay d/c.
    • in kids, dose 0.25 mg/kg produces effective sedation and reduces anxiety
  • opioids
    
    • good for attenuating SNS response/pain
  • multimodal analgesia
    
    • NSAIDS (consider antiplt, gastric mucosal, renal s/e)
    • IV tylenol
    • gabapentin, ketamine, dexamethason

Question 25

Risk factors for PONv?

Answer 25

• Additive risk factors:
  
  • choice of anesthetic technique (premed, opioid use, inhaled agent use, acetylcholinesterase use, hydration status, hypotnetion
  • type of sx (length of procedure, operative procedure, pain mgmt, gastric distention)
    
    • lap, lithotripsy, major breast sx, ENT associated with high PONV
  • patient factors (hx of PONV and motion sickness, anxiety, non-smoker, within week menstrual cycle, age, genetic predisposition)

Question 26

Prevention of PONV?

Answer 26

• Droperidol- low dose 0.625-1.25 mg
  
  • central dopamine 2 antagonist
  • very effective antie-emetic- black box for prolonged QT (>2.5 mg dose or higher)
• Dexamethasone 4-8 mg
  
  • steroids- analgesia and antiemetic benefits. last much longer. don’t know why it’s effective
  • give at beginning of case
• 5-HT antagonists- ondansetron 2-4 mg, dolasetron 12.5 mg
• promethazine/phenergan 6.25-12 mg (phenothiazine)
  
  • ​can have sig impact on anesthetic requirements and can cause delayed awakening, extrapyramidal effects
• metoclopramide 10-20 mg
  
  • D2 and 5-HT antagonist
• antihistamine
  
  • ​act on central vomiting center/vestibular pathways to prevent PONV
  • Helpful in motion induced emesis and pt undergoing middle ear sx
• neurokinin-1 (NK1) antagonist (aprepitant)
• propofol use
  
  • propofol/midazolam have been shown to have antiemetic properties that outlast their sedative effects
• scopolamine patch (anticholinergic)
  
  • ​1 mg over 3days
  • effective 2-4 hours after application
• hydration
• seaband &relief band
  
  • accustimulation at P6 acupoint
    
    • can be more effective than antiemetics

Question 27

Anesthetic techqniue for ambulatory patient?

Answer 27

• Standard of care
  
  • equipment
  • monitoring
  • resus
• ideal anesthetic
  
  • rapid onset/elimination (prop most common induction and VA most common maintenance)
  • cerebral monitoring- controversial, may prevent overdosing
  • cost effective
  • pain mgmt
    
    • use opioids carefully
    • neuraxial can be problematic- residual motor, SNS block, delays d/c with longer actin agents
    • PNB of local infiltration
    • perineual, incisonal/intraarticular catheters with continuous infusion/elastomeric balloon pump
      
      • chondrolysis reported with intraarticular local anesthetic pumps

Question 28

Epidural and spinal anesthesia for ambulatory patients?

Answer 28

• readiness for discharge limits use
• mini doses and adding opioid s(7.5 mg bupi w 20 mcg fent)
  
  • addition of fentanyl prolongs sensory but not motor blockade. appears to decrease time to voiding and full recovery.
• consider for shorter acting agents such as chloroprocaine
  
  • preferable to bupi,ropi and tetracaine
• need to f/u with call to r/o headache
  
  • HA less common now (0.5-1%) with fine-gauge, pencil point spinal needles
  • major issue prolonged motor/joint position sense block
  • most avoid lido d/t complications with neuro

Question 29

Use of bier block in ambulatory pt?

Answer 29

• remains popular in hand surgery
• failure 11% of the time

Question 30

Peripheral nerve block in ambulatory anestheisa?

Answer 30

• improved pt satisfaction, less PONV, less pain, shorter PACU stay, lower admission rate
• US improving success even in obese patients
• efficiency facilitated if PNB placed pre OR
• always r/f nerve/vessel injury
• pt may experience pain as transition to oral meds

Question 31

Local infiltration w/ MAC in ambulatory sx?

Answer 31

• extended duration LA (encapsulated Exparel)
• propofol 25-100 mcg/kg/min
• precedex 1 mcg/kg over 10 min
  
  • slower recoverytime/ bradycardia risk but useful in some cases
• infiltrated into surgical field- increased mobility and decreased need for opioids dramatically
• simplest and safest approach to reducing postop pain

Question 32

General anesthesia technique induction for ambulatory sx?

Answer 32

• Induction
  
  • NC, Mask, LMA, and GETA
    
    • tracheal intubation can cause high incidence of postop airway related complaints including sore throat, croup, hoarseness
    • sore throat incidence 18% with LMA, 45% ETT, 3% face mask
  • Short acting agents used
    
    • when VA compared with propofol, VA produced similar anesthetic conditions. lower cost, and faster emergence than prop
  • Careful w/ induction dose of muscle relaxant (don’t want it to outlast the surgery!)
  • Thermoregulation (BIG issue in the plastic surgery population)
    
    • Volatile agents vasodilate
    • Can have large 3^rd space losses/exposure
    • Can be lengthy
    • Difficult to place a BAIR hugger if sterile prepped area is large
    • BAIR controversial < 90 minute procedure (costly to put on??)
• higher incidence of s/e, but still most widely used technique
  *

Question 33

General anesthesia technique maintenance

Answer 33

• Maintenance
  
  • Inhaled agent VS TIVA
  • Use of Local Anesthetics
    
    • Remind surgeon of toxic doses (many catastrophic cardiac and neurological injuries in plastics related to toxic doses given…..)
    • Document not only your own administration but also dose given by surgeon
    • Use of LA, if effective will reduce opioid requirements
  • Opioid Analgesics
    
    • Effects on emergence
      
      • Because alfentanil has more rapid onset and shorter duration of action than fentanyl does, emergence and recovery of psychomotor function are faster after an anesthetic technique based on alfentanil (vs. fentanyl).
      • Remifentanil is an ultrashort-acting opiod analgesic with potency similar to that of fentanyl. It is rapidly metabolized by nonspecific tissue esterases, a process that allows for rapid systemic elimination, with a half-life of 8 to 10 minutes. Not good for painful cases, need another plan of action. Pain will also delay discharge
    • Effects on PONV
  • Muscle relaxation
    
    • antagonism

Question 34

MAC

Answer 34

• Anesthetic management of a case where patients remain responsive and breathe without assistance
  
  • Wont wake up w/ sternal rub → NOT MAC (that is general w/o AW)
• Utilized: simple procedures & minor surgery
• May involve one or more of the following: LA infiltration, sedatives, analgesics, etc.
• Standard of care is the same as GA or RA
• not necessarily safer. closed claims shows risk of death and brain damage same as GA
• Primary objective in MAC is to determine pt comfort, safety and satisfaction
  
  • ​up to 50% OP procedure can be performed with MAC nad would reduce cost 80%
    *

Question 35

When can a patient be fast tracked?

Answer 35

• The anesthesia provider makes the decision after MAC anesthesia
• Criteria for fast track eligibility:
  
  • Awake, alert, & oriented
  • Able to move extremities on command (dr. b says moving from stretcher to chair without help)
  • VS within 15%- 20% of normal
  • SaO2 > 94% on room air
  • Able to breathe deeply
  • No pain, nausea, or vomiting
  • 5 second head lift (if NMB given)
  • No active bleeding/risk for active bleeding

Question 36

Postop period management

Answer 36

• Pain and Nausea Management
  
  • Address pre-operatively and throughout the case
    
    • Local anesthesia infiltration
      
      • Ex: bupiv delayed onset → might need to cover w/ meds until onset)
    • Perineural catheters
    • Ketamine at induction
    • Ketorolac at emergence
    • Hydration
    • Anti-emetics
      
      • inhalational alcohol (help w/ immediate) & 10-15 mg propofol (~ 28% relapse within 30 min. though))
  • Goal: Facilitate Rapid conversion to oral analgesics
    
    • Don’t forget to warn patient regarding when regional will wear off
    • Warn if had Midaz (escort)
  • Goal: avoid emesis in the car!
    
    • Next day follow up important to truly appreciate how good (or bad) you are at preventing post-op nausea and pain control

Question 37

Discharge criteria

Answer 37

• Usually based on a scoring system: evaluates the ability to tolerate liquids, void, walk, VS stability, bleeding, pain & nausea controlled
• Criteria is controversial…..
  
  • Voiding often not required now may just u/s bladder
• Remind patient no driving, no power tools, no business decisions for 24 hours
  
  • Even if propofol just used
• Written and oral instructions to patient and responsible adult to accompany patient home
• 3 most common reasons for delay????
  
  • N/V
  • Over sedated
  • Pain

Question 38

Laparoscopic and robotic sx compared to open?

Answer 38

• used in GI (gastric, colonic, splenic, hepatic, gallbladder); gynecologic (hysterectomy); urologic (nephrectomy)
• Compared w/open surgery usually associated with:
  
  • Lower pain scores and opioid requirement (less tissue damage)
  • Earlier ambulation and return to normal activities
  • Lower incidence of post-operative ileus
  • Usually faster recovery, shorter hospital stay (SDS)
  • Reduced postoperative pulmonary/diaphragmatic dysfunction: Quicker return to preoperative pulmonary function
    
    • Pneumoperitoneum created may lead to diaphragmatic dysfx that persists postop
  • Less stress response & less wound complications
    
    • Pneumoperitoneum → causes major stress response (activates RAAS/SNS)
  • Lower cost (usually)

Question 39

Relative contraindications to laparoscopy

Answer 39

• Inc. ICP- head is down, increased abd pressure causing increased ICP
  
  • Hydrocephalus, brain tumor, head trauma
• Hypovolemia
  
  • Pneumoperitoneum effect on preload
• V/P Shunt or peritoneojugular shunt
  
  • (OK if have unidirectional valve resistant to IAP)
• Severe CV disease
• Severe Respiratory disease

Question 40

Traditional lap approach?

Answer 40

• Veress needle → insufflate CO2 to create pneumoperitoneum (~ 50 mmHg intraabd pressure) → then switch veress needle for Trocar
  
  • Placement of trocar- Caution d/t increased risk of damaging bowel/vessels

Question 41

Most important thing in regards to robotic surgery

Answer 41

• ** Important
  
  • Robot arms and OR table may not move together. When robot docked and arms are inside the patient → paramount to avoid dyssynchronous movement of the OR table to avoid tearing injuries of tissue inside pt
  • NO DYSSYNCHRINOUS MOVEMENT
• EndoWrist instruments- surgeon movements miniaturized, precise tiny movements

Question 42

Considerations for robotic sx? (Setup)

Answer 42

• Arms are tucked → get 2^nd IV after induction
• After arms tucked, ensure IV works
• A-lines placed before
• Place 2^nd noninvasive BP cuff and tubing available to have just in case
• Positives: minimal tissue damage, smaller incision, precise movements

Question 43

Examples of sx that can be done robotically?

Answer 43

• General laparoscopic
• Hysterectomy
• Prostatectomy
• Nephrectomy
• Cardiac surgery
• Colectomy
• Thoracoscopic
• Transoral otolaryngologic procedures- no cavity to inflate
  
  • All involve pneumoperitoneum

Question 44

How is the pneumoperitoneum created? complications with each method?

Answer 44

• Pneumoperitoneum – access sx site w/o damage to surrounding structures
  
  • Carbon dioxide (gas of choice)- acidosis
  • Inert gases- CV depression
  • Gasless laparoscopy- fan retractor or external wall retractor (creates an abdominal wall lift)(increa sx time, less view)

Question 45

CO2 pneumoperitoneum?

Answer 45

• Surgical exposure facilitated by gas insufflation
• CO₂ gas of choice bc:
  
  • More soluble in blood than air, helium, oxygen or nitrous oxide.
  • Capacity for carriage in the blood- natural for blood to carry
  • Rapid elimination (better outcome compared with He embolus)
    
    • No matter which gas used, some will be absorbed → and blood gets rid of CO2
  • Nonflammable/Noncombustible can be used with diathermy/cautery (does not support combustion – N2O does)

Question 46

Max IAP during lap sx?

COnsiderations?

Answer 46

• Intraabdominal pressure < 15mmHg or 20 cmH₂0
  
  • Minimize CV and respiratory impacts
    
    • Vagal innervation of peritoneum: increase pressure = increase vagal resp (dec HR, bradydysrhythmias)
• Considerations:
  
  • Expected progressive rise of PaCO₂15-30 min after initial insufflation → then plateau reached (absorption into lymph and venous system)
    
    • If continues to increase an hour or so after case → search for pathologic cause (embolism, emphysema, MH, etc.)

Question 47

Why is laparoscopic considered ptoentially a high risk procedure

Answer 47

• Pneumoperitoneum + positions required = pathophysiologic changes to cardiac and resp fxn
• Often long duration esp if residents training
• Risk of unsuspected/occult visceral injury
  
  • No visualization of the entire surgical field (ex: ETCO2 suddenly goes away and can’t get BP)
• Difficulty in evaluating the amount of blood loss
• At risk aspiration of gastric contents- from increase pressures

Question 48

What causes the increase of PaCO2 with lap sx?

Answer 48

1. Absorption of CO2 from the peritoneal cavity – primary
   
   1. R/t vascularity and surface area (pelvic cavity* vs peritoneum)
2. Abdominal distention
   
   1. VQ mismatch, FRC ↓, decreased pulmonary compliance
3. Patient position
   
   1. VQ mismatch- Trendelenburg/reverse, PPV
4. Volume-controlled mechanical ventilation – VQ mismatch
5. Depression of ventilation by anesthetic agents if spontaneous breathing
6. CO₂ emphysema (SQ or body cavities)
   
   1. See CO2 increase → CO2 goes into SubQ tissue planes and accumulate
      
      1. Prolonged ETCO2 elevation, PaCO2, and acidosis into postop period
7. Capnothorax- escapes into and around lungs
8. CO₂ embolism- trocars into vessels
9. Selective bronchial intubation- from extreme trendelenber

Question 49

Hemodynamic changes with pneumoperitoneum

Answer 49

• Decreased myocardial contractility (CO impact depends on CO₂ insufflation, position)
  
  • High CO2 and insufflation → decreases contractility
    
    • Depends on hydration status, position, and underlying conditions
• Decreased VR
  
  • Mechanical compression of IVC
• Decreased LVEDV
  
  • d/t dec venous return
• Increased intrathoracic pressure
  
  • leading to compliance issues
• Pulmonary vasoconstriction
  
  • Result of VQ mismatch
    
    • As CO2 incre lungs → promotes vasoconstriction (why hypoxia)
    • CO2 incre → vasodilation in brain
• Increased right atrial and PA occlusion pressures
• Minimal increase HR
  
  • SNS stimulation and RAAS
• Increased aBP, SVR
  
  • SNS stimulation and RAAS
  • increased SNS tone- catecholamines, renin-angio, vasopressin, arterial compression by high IAP) may increase myocardial wall tension and O2 demand
  • not only vagal response, but also SNS or ANS response d/t highly innervated areas
    
    • someone with CAD → increase risk to MI
• Increase risk for arrhythmias

Question 50

Hemodynamic consequences of pneumoperitorneum? How to tx?

Answer 50

• Drop in CO from →
  
  • Dec VR (txmt: fluid loading before pneumoperitoneum placed)
  • Catecholamine/humoral release (txmt: use BB, alpa 2 agonist → reduce SNS tone to reduce responses)

Think: can they tolerate dec VR, increase afterload → if not, may need open

Question 51

Regional hemodynamic alterations?

Answer 51

• Usually unchanged splanchnic
  
  • mechanical compression + neuroendocrine vasoconstriction balanced by hypercarbic dilation
• Renal:
  
  • Decreased GFR, renal plasma flow, urine output
• Neuro:
  
  • Increased cerebral blood flow and ICP in steep Trendelenburg
  • Increased IOP in steep Trendelenburg

Question 52

Induction considerations for lap sx

Answer 52

• GA w/ cuffed ETT & controlled ventilation (gold standard)
  
  • increased minute ventilation (20-30%)
  • increased PIP often required (but not too much bc VR)
    
    • Volume control → pressure control to get PIP to good level
  • Adjust RR, Vt (6-8ml/kg), PEEP (5-10cmH20) & PIP
    
    • Goals:
      
      • ETCO2 = 35mmHg
      • PIP low 30’s cmH20
      • Intra-abdominal pressure limit < 15 mmHg – to best avoid CV compromise
  • aspiration risk- need cuff
• RA has been used – risky
  
  • need high block T4-5 (SNS denervation- loss of cardiac accelerator fibers) more difficult to compensate for CV, ventilatory changes, shoulder & distention pain incompletely alleviated
• ASA III-IV and/or abnormal gradient PaCO2:ETCO2 invasive monitors
  
  • Blood gas and BP measurements

In a study by Exter et al CO was decreased to a maximum of 28% at a IAP of 15mmHg whereas CO was maintained at a insufflation pressure of 7mmHg. B1063

Barash 8^th – nice discussion of ventilation issues.

Question 53

GETA vs LMA in lap sx?

Answer 53

• ETT**
  
  • Secure airway (aspiration protection)
  • Control of ventilation
• ProSeal LMA (Controversial):
  
  • Spontaneous Ventilation
  • Lower incidence of sore throat
  • 8/9^th editions cite studies: lower pain scores, less analgesic medications, less PONV
    
    • “still cannot yet be regarded as completely safe”
    • 1/3 of deaths during lap surgery occurred during GA without ETT (6^th ed) – ETT provides safety!
  • Unable to:
    
    • Secure airway (aspiration risk)
    • Control Ventilation
    • Administer muscle relaxation
• Lap chole and gynecologic procedures: Pro- seal associated with improved outcomes – M9th2263 good discussion of the current state of the evidence.

Question 54

Positioning for lap sx

Answer 54

• Prevent nerve injury- common peroneal nerve (lithotomy), be very careful with branchial plexus (shoulder braces, etc.)
• Tilt not to exceed 15-20 degrees
• Make changes slowly*
  
  • Esp in position for long time → can see drop in BP
• Recheck the ETT position after every position change
• Consider less aggressive fluid replacement in head down position (edema)

Question 55

Anesthesia for lap sx: GA maintenance

Answer 55

• Standard maintenance
  
  • balanced techniques appropriate using volatile agent, opioids, or TIVA
  • (+/-avoid N2O)
• Consider propofol TIVA if PONV strong
• Continue muscle relaxation – possible to use adjunct meds to avoid use
  
  • Required for robotic
• Monitor pulmonary & hemodynamic status
  
  • Dysrhythmias, vagal responses, BP low → ask surgeon to decrease insuff pressure
  • PIP 30-40’s
  • Fluid management – best practice unclear
• Watch for endobronchial intubation during position changes (head up or down)

Question 56

What to do if converted to open procedure?

Answer 56

• Supine position
• New fluid plan
  
  • 3^rd space losses will increase
• New pain management plan
  
  • opioid requirements will change
• New ventilator settings – may need to reduce rate and increase Vt
  
  • No exogenous source of CO2

Question 57

Maintenance phase surgical complications for lap sx?

Answer 57

• Falls or position shifts resulting in injury
• Vascular injury
  
  • (trocar insertion/veress needle – aorta, ICV, iliac vessels, cystic/hepatic arteries, retroperitoneal hematoma)
• GI
  
  • (trocar insertion/veress needle- bowel, liver, spleen, mesenteric)
• Cardiac
  
  • (dysrhythmias- hypercarbia, increased vagal tone with peritoneal traction, BP changes)
• SQ emphysema – extra-peritoneal insufflation
  
  • accidental
  • Most common → inguinal hernia repair (result in acidosis into postop period)
• Capnothorax, capnomediastinum, capnopericardium
  
  • diaphragm defect, pleural tear, bullae rupture, COPD pts– high degree of suspicion can be lifesaving
• CO2 embolism
  
  • direct needle placement in vessel, gas insufflation into abdominal organ → DANGEROUS

Question 58

Gas Embolism pathophys

Answer 58

• Depends on size of bubbles and rate of entrainment
• Vapor lock in vena cava and RA → dec flow to pulm circulation and body
• Obstruction to venous return
• Acute RV hypertension = paradoxical embolism
• Circulatory collapse
• Small bubbles over time results in pulmonary entrapement.
• Large bubbles under high pressure causes gas lock in vena cave and right atrium.
• V/Q mismatch develops, Increased dead space and hypoxemia,
• Acute RV HTN, may occur causing paradoxical embolism to the cerebral and coronary vasculature

Question 59

Gas embolism dx tools?

Answer 59

• In the ideal world….
  
  • Trans-esophageal echo (TEE)
  • Swan-Ganz Catheter
  • Precordial Dopplers– not standardly used
• In the real world……
  
  • ETCO2 decrease- early**
  • Pulse oximetry (hypoxemia)- later sign
  • Esophageal stethoscope- millwheel sound (change in heart tone)
  • Aspiration of gas from CVP
  • Hypotension

Question 60

Gas embolism treatmnet

Answer 60

• Stop insufflation and desufflate
• Positioning
  
  • Steep Trendelenberg
  • left lateral decubitus
• D/C N20 and give 100% FiO2
• Hyperventilate
• Place CVP – try to aspirate
• CPR
• Consider CPBypass

Question 61

Postop consideration for lap procedures?

Answer 61

• Procedures are associated with intra-abdominal, incisional, and shoulder pain (irritation of diaphragm and/or visceral pain from biliary spasm)
• Opioids + NSAIDS + acetaminophen + dexamethasone + local anesthetic infiltration (incisional and intraperitoneal)
• TAPS block (transversus abdominus place – place local between the internal oblique and transversus abdominus muscles can be useful in larger surgeries – not clear if helpful in more straightforward laparoscopic procedures – Intraperitoneal is controversial – appears highly effective but the dose and duration of infusion has not been reliably determined. At this point not recommended but no toxicity has been reported Barash 7^th.
• Post operative Nausea and Vomiting
  
  • 40-75% of patients after laparoscopic procedures
    
    • young women and lap chole at increased risk
  • Propofol utilization
  • Gastric decompression
  • Anti-emetic prophylaxis
  • Opioid use increases incidence
  • Limit opioids and administer ondansetron, dexamethasone for best results (beginning of case)