VAE & LAST Flashcards
Mechanism of a VAE
- CO2 bolus enters venous circulation
- travels back to R atrium via IVC
- causes a gas lock blocking flow from RV to pulm system
- decreased VR & CO
- hemodynamic collapse
Symptoms indicative of VAE
- rapid decrease in EtCO2
- HoTN
- hypoxemia
- increased CVP
- EKG changes
Most sensitive monitoring modality for air
TEE
Decreased EtCO2 seen in VAE is d/t…
- decreased pulmonary BF
- increased alveolar dead space
- dilutional expired CO2
Treatment of VAE should include…
- communicate
- release pneumoperitoneum
- flood field with NS
- d/c N2O
- Durant’s maneuver
- place surgical site below level of heart
- 100% O2
- CVP placement to aspirate air from RA
- pressors if needed
- rapid IVF
Key symptom that differentiates fat embolism from air embolism
fat embolism = petechiae
High risk patients for VAE
- sitting positions
- op site above level of heart
- line placement
- operative hysteroscopy
- CO2 insufflation
Areas with greatest potential for intravascular absorption of LA
I Think I Can Please Everyone But Susie & Sally
IV - Tracheal - Intercostal - Caudal - Paracervical - Epidural - Brachial Plexus - Subarachnoid - Sciatic - SQ
Symptom presentation of LAST
- CNS excitement
- Seizure or CNS depression
- CV toxicity
wide presentation
Mild to moderate LAST symptoms
- circumoral numbness
- disorientation
- metallic taste
- tinnitus
- vision changes
Severe LAST symptoms
- coma
- resp arrest
- seizure
- unconsciousness
At exceedingly high LA plasma concentrations…
- cardiac arrest
- HTN –> HoTN
Conditions that potentiate LAST
Why?
- hypoxia
- hypercarbia
- acidosis
–> vasodilate cerebral vessels, enhancing delivery
–> H+ ions bind to protein and decrease protein binding of LA
Lipids should be initiated in LAST…
at first sign of potential LAST
Preferred medication class to treat LAST-associated seizures:
Benzos
or
Propofol
Lipid dosing
> 70kg:
100mL bolus over 2-3min
200-250mL infusion over 15-20min
<70kg:
1.5mL/kg bolus over 2-3 min
0.25mL/kg/min infusion
Maximum lipid dose
12 mL/kg
Patient experiencing LAST had their first lipid bolus and 15min infusion but remains unstable. Next steps…
repeat initial bolus (100mL)
double infusion rate
Effects of intralipids
- lipid sink (sequesters LA)
- enhanced FA metab
- inotrope (increased Ca2+ influx)
- membrane effect (impairs LA binding to voltage-gated Na channels)
Complications of LAST
- CV collapse
- hypoxic brain injury
- status epilepticus
- recurrence of systemic toxicity
- death
LAs affect 3 cardiac functions:
1) cardiac action potential
2) myocardial function
3) SVR
LA with greatest affinity for Na+ channels:
Bupivacaine
(greater affinity for Na+ channels and remains at receptors for longer, makes resuscitation more difficult, higher CV morbidity)
Rate the LAs on difficulty of cardiac resuscitation
Bupivacaine > Levobupivacaine > Ropivacaine > Lidocaine
