Monitoring Anesthesia Guidelines Detailed
Transcript of Monitoring Anesthesia Guidelines Detailed
Monitoring Anesthesia
Guidelines Detailed organized from the
2011 AAHA Guidelines for
Anesthesia Monitoring
Ken Crump, AAS, AHT
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Monitoring AnesthesiaReference: 2011 AAHA Guidelines
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2011 AAHA Guidelines Suggestions for Monitoring Anesthetized Patients
• Electrocardiogram (ECG) • Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG)
• Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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Pulse Oximeter (SpO2)
• Indicates the % oxygen saturation of hemoglobin– Can be PCV dependent
• Highly positional• “Pulse” is more
trustworthy than “Oximeter”
• It tells you that the heart is responding to the electrical activity– It displays a pulse wave
• Don’t trust the numbers without a wave form– Pulse oximeters that only
display a number are very unreliable. You need to see a wave form to interpret the number
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Pulse Oximeter (SpO2)
The biggest problem with Pulse Oximeters
• Their readings are most often believed when they are good, and ignored when they are bad.
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG) • Pulse oximeter (SpO2)
• Arterial blood pressure monitor – Direct intra-arterial BP: Most
accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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Blood Pressure Monitor
The goal of monitoring blood pressure is to maintain a mean
arterial pressure (MAP) of 60mmHg to assure adequate
perfusion of vital organsSystolic = amount of pressure in the arteries during contraction of the heartDiastolic = amount of pressure in the arteries between heart beatsMean = average (mean) pressure in the arteries during one cardiac cycleCalculating the MAP = [(Systolic – Diastolic) / 3 ]+ Diastolic
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Blood Pressure Monitor
Dorsal pedal arterial catheterization
Direct intra-arterial blood pressure monitor• Most accurate• Advanced
technique• Technically difficult
to achieveNote: Pressure transducers are expensive – there is another less expensive way
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Blood Pressure MonitorIndirect Blood Pressure• Technically easy to achieve• Not very accurate in animals• Best to monitor trends
Doppler• Reads only systolic arterial
pressure (SAP)• You estimate MAP based on SAP• Be concerned when SAP is below
90 mmHg• Cuff width 40-50% circumference
of limb• Can be very positional
Oscillometric• Reads only MAP• Displays SAP, MAP, and DAP• Cuff width 40-50% circumference
of limb• Can be very positional
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG) • Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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Monitoring Temperature
Thermometer:
• Use esophageal or rectal probe to monitor continuously
• Take rectal temperature with conventional thermometer periodically
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Monitoring Temperature
Hypothermia occurs in more than 80% of anesthetized cats and dogs.
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Monitoring Temperature
Hypothermia Contributors:• Small body size• Drug-altered
peripheral perfusion• Intubation bypasses
the nose• Breathing cold gases• Radiated heat loss
from skin surface• Open body cavities• Water during
dentistry
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Peri-Anesthetic Hypothermia
A review of the survival rates of Yorkshire Terriers after portosystemic shunt surgery showed the single most prognostic indicator for survival was postoperative temperature.
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Each stage of a procedure presents different hypothermia challenges…
• Premedication
• Clip and Prep
• Surgery
• Recovery
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3-step solution to hypothermia
1. Pre-warming
Prevents initial 1o – 2oF heat loss
2. Warm inspired gases
Prevents 2o – 5oF loss during clip and prep
3. Warm air blankets
Porous blanket / low air flow traps heat, warms animals
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG) • Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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Capnometer / Capnograph
• Measures / displays CO2 in expired / inspired gas
• Measures respiratory rate
• Reliable– More reliable than
SpO2
• Informative– Many inferences can
be made based on CO2
• If I could only have one monitor, it would be CO2
Go to Making Anesthesia Easier blog post “Why Monitor CO2?”
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Why Monitor CO2
End-tidal CO2 monitoring is a valuable non-invasive, low risk assessment tool for the anesthetist.
• It tells you if the endotracheal tube is in the trachea
• Indicates changes in cardiac output
• Detects– Extubation– Disconnection– Cardiac arrest
• (faster than SPO2)• (faster than ECG)
• Useful to assess effectiveness of CPR Respiration rate
• Detects inspired CO2– Dead space– Circuit misfit (resistance)
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Why Monitor CO2
• Indicates ventilation status (hypo/hyper-ventilation)– Breathing is about getting rid
of CO2
– Ventilation is defined by levels of CO2
– Normal ETCO2 levels are 35-45 mmHg.
– Normal healthy animals can tolerate levels up to 60-70 mmHg• Mild hypercapnia drives the
cardiovascular system
• Hold Your Breath!– Experience mild hypercapnia
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG) • Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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Anesthetic Gas Analyzer
• Measures inspired and expired inhalant gas concentration
• Fun– Allows for deeper
understanding of oxygen / gas delivery
• Who has one of these, anyway?
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2011 AAHA Guidelines Suggest
• Electrocardiogram (ECG) • Pulse oximeter (SpO2) • Arterial blood pressure monitor
– Direct intra-arterial BP: Most accurate, but technically difficult to perform
– Noninvasive BP (Doppler or oscillometric monitor):
• Technically easy, but can be inaccurate.
• Evaluate trends in conjunction with other patient parameters.
• Select cuff width of 40–50% of circumference of limb.
• Thermometer: – Esophageal probe or periodic
rectal temperature with conventional thermometer
• Anesthetic gas analyzer:– Measures inspired and expired inhalant
concentration
• Capnometer/capnograph:– Measures and/or displays CO2 in expired and
inspired gas, and respiratory rate
• Physical observations – Visualization (e.g., eye position, mucous
membranes, chest excursion, blood loss, bag volume, and movement with ventilation, equipment function)
– Palpation (e.g., pulse quality, jaw tone, palpebral reflex)
– Auscultation (heart, lungs): Precordial or esophageal stethoscope
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The Vet Tech Anesthetist
AAHA Guidelines:Successful anesthetic management requires trained, observant team members who understand:• Anesthesia drugs and their
effects• How to use anesthetic and
monitoring equipment• What is normal and abnormal
in a patient’s response to anesthesia
• How to react to abnormal responses effectively
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And…
• Heart rate• Respiration rate• Pulse quality• Response to surgical
stimulation• Status of the surgical
procedure• [Sometimes while answering the
phone, recovering patients, folding laundry, pre-medding the next patient, tying in surgeons, opening packs, wrapping packs, wishing you’d brought lunch…]
• Reflexes– Palpebral– Swallow– Pedal– Corneal– Laryngeal
• Jaw Tone• Eye Position• Pupillary Light Response
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Post Op / Recovery
Slow Down!A fast extubation rarely leads to a quality recovery. Emergence from general anesthesia is best when it's gradual.• Do NOT reverse drugs to
hasten extubation.• Allow the patient to gradually
emerge from general anesthesia, keeping pain relieving drugs intact.
• Often the drugs you want to reverse are of the most value to the patient at that time.
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Post Op / Recovery
We are all watching the clock and trying to get to our next case. And you can't leave your patient until it's extubated. But a comfortable emergence from general anesthesia is the beginning of a smooth recovery.• Finish the anesthetic record while
you sit with the patient.• Take the patient with you to your
next case, and monitor extubationfrom there
• Plan emergence and extubation of your next patient before the surgery is over– This is a call-back to "Know the
procedure" during your preanesthetic evaluation.
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