L9: Monitoring during Anesthesia (Tenenbaum) Flashcards
what systems are monitored at minimum?
CNS CVS Respiratory Renal (temp)
signs to look for when assessing whether patient is in good plane of anesthesia***
position of eye movement m. tone certain reflexes response to surgical stimulation nystagmus (esp. in horse) shivering eye reflexes present
signs of LIGHT plane of anesthesia
- central eye position
- cessation of limb movements
- m. tone remains
- response to sx stimulation
- nystagmus
- eye reflexes
- shivering
- moist cornea
signs of MEDIUM plane of anesthesia
- no spontaneous movement
- no reflex movement
- no change in hemodynamic or breathing during sx stim.
- mod. m. tone
- dec. in tidal volume
- no palpebral reflex
- no shivering
- ventromedial rotation of eye
- small pupil aperture
- moist corneas
signs of DEEP plane of anesthesia
- dec. in Vt
- abd. breathing
- eyes fixed centrally
- no reflexes
- bradycardia/hypotension and worsening of hemodynamic fx
- dilated pupil
- dry cornea
causes of white/pale mm
anemia
vasoconstriction
lack of circulating fluid
causes of cyanotic mm
lung disease
dec. in oxygen flow to the breathing circuit
endobronchial intubation
causes of red/bright pink mm
hypercapnia
common arrhythmias
sinus tachycardia
sinus bradycardia
2nd degree AV block
VPCs
ECG:
- good for detecting HR and rhythm but not in evaluating cardiac fx and heart disease
- each patient is different!**
- N dog: 70-140
- N cat: 110-140
- N horse: 30-45
mean BP should be maintained above:
60mmHg (70 in horses)
direct BP measurement
- arterial catheter connected to pressure transducer
- provides real time beat by beat pressure monitoring
- invasive
indirect BP measurement
- aka sphymomanometry
- use of pressure cuff, doppler shift pulse detectors
- if cuff to wide or tight, underestimate blood pressure
- systolic should be >80mmHg
oscillometric method
- cuff inflated to a pressure and pressure is slowly released as the monitor detects the oscillations in the cuff caused by the blood flow under the cuff
- MAP >60mmHg
how can CO be measured
invasive thermodilution
-not used routinely
how is pulse oximetry measured
light absorption of 2 different wavelengths at fast intervals during pulsations
- detects reduced Hb and oxyHb
- % of saturated Hb is calculated
- sensitive to movement, cold, vasoconstriction
- should be >95%
central venous pressure
- P within the thoracic vena cava
- balance b/w venous blood volume and contractility of the heart
- dec. CVP: hypovolemia
- inc. CVP: fluid overload
urine output depends on
CO
blood volume
renal function
normal tidal volume***
10-15mg/kg
blood gas analysis
- measures lvls of oxygen and CO2 in arterial blood
- provides acid-base status
- can also measure electrolytes/glucose/lactate
capnography**
-measures the end tidal CO2 and the inspired CO2 tension
-connected between the patient and the breathing system
-useful to measure:
hypoventilation
hyperventilation
apnea
disconnection
rebreathing
obstruction
embolism
-provides info on:
1) adequacy of ventilation
2) CV system
3) patient’s metabolism
phases of the capnogram: phase I***
Inspiratory baseline
- represents the inspiration of fresh gas with CO2
- should stay at the level that corresponds to zero concentration of CO2
phases of the capnogram: phase II***
Expiratory upstroke
- occurs shortly after inspiration ends
- caused by the rapid washing out of the fresh gas in the anatomic space and then replacement by CO2-rich alveolar gas
- should be steep
phases of the capnogram: phase III***
Expiratory plateau
- represents continuous exhalation
- horizontal line if no V/Q mismatch, but usually CO2 slowly increases as the gas from the lung areas with lower rate of ventilation to perfusion reaches the sampling site
phases of the capnogram: phase IV***
Inspiratory downstroke
- occurs shortly after expiration ends
- represents the rapid washing out of the CO2 by fresh gas as inspiration starts
- should be steep
how is pulse oximetry an indicator of the resp. system
lower oxygen tension means lower arterial oxygen saturation
-will also see low saturation w/ pulmonary embolism
anesthetic complications of hypothermia
- decreased anesthetic requirements
- not responding to anticholinergics
- prolonged recovery
- cardiopulmonary depression
