SRNA Presentations: Part 2 Flashcards
What is piezoelectricity?
Ability of certain materials to generate AC voltage when subjected to stress or vibration-or vibrate when subjected to AC voltage
- most common piezoelectric material is quartz
Who is considered the âfather of echocardiographyâ?
Dr Ingle Edler
How does ultra sound work?
An ultra sound beam is generated by oscillating crystals
- crystals are excited by electrical impulses (piezoelectric effect)
- U.S. waves sent from transducer, through tissues, return to transducer as reflected echos
- waves reflected at tissue surfaces of different density
* If no difference in tissue densityâ> no echos produced
(Homogenous fluids like blood, urine, ascites are seen as echo free structures)
What angle provides optimal ultrasound reflection?
90 degrees
What is M-mode echocardiography?
- simplest type of echo
- image is similar to a tracing
- useful in measuring size of heart structures, thickness of heart walls and size of heart itself
What is doppler echo?
Assesses blood flow through chambers and valves
What is color Doppler?
- enhanced form of Doppler echo
- different colors used to designate direction of blood flow
What is 2-d echo?
Used to view motion of heart structures in real time
What is 3-d echo?
View of heart structure in greater depth
Also in real-time
What do the different colors mean in color Doppler?
Blue= away from probe Red= toward probe Green= turbulence
Advancing probe into esophagus allows for what types of views?
Upper, mid and transgastric
-probe can then be turned right and left
What can be viewed from an ME4 chamber view?
Chamber size Ventricle function MVD TVD Atrial-septal defect Pericardial effusion
Unless contraindicated, TEE should be used:
In all open heart and thoracic aortic procedures
- should be considered in CABGs
- case by case basis for kidsâ> unique risks
- use in non-cardiac surgery if suspected CV pathology ay result in severe hemodynamic, pulmonary, or neuro. Compromise
What is the primary use of TEE?
Diagnose hemodynamic instability caused by MI, heart failure, valve abnormalities, hypovolemia, tamponade
- estimates SV, CO, intracavitary pressures
- dx structural hart disease (PE)
- guides surgical interventions/medications
What are absolute contraindications for TEE?
- esophageal stenosis
- large esoph. Diverticuli
- recent esoph. Surgery/sutures
- know esoph. Interruptions
Why is TEE especially risky for children?
Even a probe of appropriate size may cause airway obstruction, or compress descending aorta
What is blood pressure?
The driving force of blood against arterial walls
What are the ranges form hypertension and hypertensive crisis?
HTN= >_ 140/90
Hypertensive crisis= >_ 180/120
How do you calculate MAP?
SVR x CO
1/3 (SBP -DBP) + DBP
How does the size of BP cuff effect the BP measurement?
Cuff too large will not restrict flow properly (underestimates BP)
Cuff too small cuts off too much blood flow (overestimates BP)
** make sure 1 fingertip can fit beneath cuff **
What are indications for using an arterial line?
When beat to beat monitoring is required for:
- multiple comorbidities (anticipate instability)
- certain surgeries: cardiothoracic, neuro, neurovascularâ>prolonged surgery of any type
- need for frequent arterial sampling
When is an arterial line contraindicated?
When arterial supply compromised
- Reynaudâs, thromboangitis obliterans (Buergerâs disease)
What does the art line wave form tell you about MAP?
AUC = MAP
How can you assess hypovolemia from an art line waveform?
Will have shorter height during inhalation while on mechanical ventilation
What method of measurement does an automatic NIBP machine use?
Oscillometric
What part of waveform represents diastole?
After the dicrotic notch
What sounds are heard during auscultation of manual BP?
Kortokoff sounds (turbulence) are heard when an artery is partially constricted
What are some risks of cannulation of an artery?
Limb ischemia, hematoma, air emboli
What situation indicates the need for art line BP monitoring?
Pt with metabolic acidosis, scheduled for a lengthy procedure
What type of feedback system is thermoregulation?
Negative feedback system
How does thermoregulation work in the body?
Thermo-sensitive receptors send info to hypothalamus when excited
- excited when temperature is sensed outside of threshold - brain sends messages to modify behavior in order to modify temp (shivering, removing clothing, etc)
What plays the most effective role in thermoregulation?
Behavior: clothing, changing environment, changing body position, voluntary movement
* a pt under GA cannot âbehaveâ
What are the types of heat loss and percentages they account for in the body?
Convection: 30%
Conduction: 20%
Radiation: 40%
Evaporation: 10%
Hypothermia can cause:
- cardiac arrhythmias and ischemiaâ> j wave
- increased peripheral vascular resistance
- left shift
- reversible coagulopathies
- AMS
- impaired renal function
- increased post-op catabolism and stress response
- delayed drug metabolism
- impaired wound healing/increased risk of infection
What is a J wave (Osborne wave)?
Associated with hypothermia
- slow upright deflection at the end of QRS and early part of ST segment
- ST elevation often reported with âJâ waves
What are anesthetics that interfere with thermoregulation?
- inhaled gases: vasodilation
- spinal/epidural: vasodilation, altered perception of temperature
- GA: vasodilation, heat redistribution
- opioids: depress sympathetic response and decrease threshold for cold response
What is phase 1 of hypothermia?
1st hour of GA
Core temp drops 1-2 degrees C
Vasodilation and heat redistribution
What is phase 2 of hypothermia?
3-4 hours of surgery
Gradual decline (linear) in core temp
From pt to environment
What is phase 3 in hypothermia?
Plateau
Core temp reaches a steady state
What is malignant hyperthermia?
Caused by anesthetic gases or succinylcholine
- agents cause Ca release, but stop reabsorbing Ca back â> continuous reaction of muscle contractionâ> hypermetabolic state
How do you recognize malignant hyperthermia?
Seen ~ 1 hour after receiving inhaled gas or succinylcholine
- WILL SEE A HUG (RAPID) SPIKE IN ETCO2 *** drastically elevated
- tachycardia, fever, muscle rigidity
- NMB reversal agents will do nothing to reverse MH
- itâs a hypermetabolic state with increased sympathetic activity
- metabolic acidosis, cyanosis, mottling
What is the only treatment for MH?
Dantrolene 2.5mg/kg - mix with 60mL sterile water Or Ryanadex 2.5mg/kg - mix with less volume * both require multiple doses * Treatment involves getting Ca reabsorbed
What is MH caused by?
A mutation of Ryanodine (Ryr 1) receptor on chromosome 19â> GENETICS
What is the most common condition confused for MH?
Elevated CO2 caused by insuflation
- important to recognize early and rule out other casesâ> start treating ASAP
- dantrolene will not harm pt if given outside of MH (may cause muscle weakness afterwards)
What are other conditions that mimic MH?
- neuroleptic malignant syndrome (NMS):
- pts receiving antidopaminergic agents
- elevated temp, muscle rigidity, dyskinesia
- reversing non-depolarizer will reverse rigidity in NMS
- pts receiving antidopaminergic agents
- thyroid storm:
- tachycardia/tachyarrythmias, elevated temp, hypotension, CHF
- hypokalemia is common
- tachycardia/tachyarrythmias, elevated temp, hypotension, CHF
- drug induced hyperthermia
- serotonin syndrome or from elicit drugs
- environmental hyperthermia
- not uncommon in peds from excessive warming devices
- brainstem/hypothermic injury
- sepsis
- transfusion reaction
What does the pneumonic âSome hot dude better give iced fluids fastâ mean?
Stop triggering agents Hyperventilate/Hunderd percent o2 Dantrolene (2.5mg/kg) up to 10 mg/kg Bicarbonate Glucose and Insulin IVF and cooling blanket Fluid output monitoring/furosemide Fast HR-tachycardia
What are some active warming devices?
- Kim Clark vest: with warm water running through it
- bear hugger
- IVF warmer
- warm blankets are NOT active warmersâ> they do not produce heat
What type of reaction is the CO2/soda lime reaction?
Exothermic
Where is the optimal location to place an esophageal temp probe?
Lower 1/4 of esoph. Is warmest and most stable site
What are common temp. Monitors in the OR?
- axilla, oral, rectal, or esophageal probes
- skin- forehead sticker
- swan-ganz thermistor