Clinical Monitoring Flashcards
Standard V Monitoring Standards dictates that what should be monitored at ALL times?
- ventilation continuously
- oxygenation continuously
- cardiovascular status continuously
- body temperature continuously
- neuromuscular function and status
- patient positioning
Verify intubation of the trachea by ____.
auscultation, chest excursion, and confirmation of carbon dioxide in the expired gas, continuously monitor end-tidal carbon dioxide during controlled or assisted ventilation including any anesthesia or sedation technique requiring artificial airway support; use spirometry and ventilatory pressure monitors as indicated
Monitor cardiac status via ___
EKG and heart sounds, record BP and HR at least every 5 minutes
What are the three fundamental assessment techniques for a CRNA?
- Inspection of the patient can provide info regarding the adequacy of oxygen delivery and carbon dioxide elimination, fluid requirements, as well as positioning and alignment of body structures.
- Auscultation is used to verify correct placement of airway devices such as the endotracheal tube and laryngeal mask airway, to assess arterial blood pressure (BP), and to continually monitor heart sounds and air exchange through the pulmonary system.
- Palpation can aid the anesthetist in assessing the quality of the pulse and degree of skeletal muscle relaxation, as well as locating major vascular structures when placing central venous lines or performing regional anesthesia techniques.
The maximum intensity of stridor is heard ___ and signifies ___.
Which respiratory phase?
Larynx
Signifies Laryngeal Stenosis
Heard on inspiration and expiration
The maximum intensity of wheezes are heard ___ and signifies ___.
Which respiratory phase?
Bronchia or Trachea
Signified narrowed airways
Usually expiration
The maximum intensity of crackles are heard ___ and signifies ___.
Which respiratory phase?
Peripheral lung
Occluded airways
Usually inspiration
Normal bronchial lung sounds are heard louder on ___.
Maximum intensity ___.
expiration
trachea, thoracic inlet
Normal vesicular lung sounds are heard louder on ___.
Maximum intensity?
inspiration
peripheral lungs
Use the stethoscope to auscultate the trachea to ____
confirm ventilation during natural airway and poor capnography
Heart Sounds Location
Locations for Auscultation
What is a precordial stethescope?
A precordial and/or esophageal stethoscope is most seen in pediatric anesthesia and used for continuous respiratory and cardiac monitoring
A precordial stethoscope is a heavy, bell-shaped piece of metal placed over the chest or suprasternal notch.
Esophageal Stethoscope (general facts)
The esophageal stethoscope is a soft plastic catheter (8–24FR) with balloon-covered distal openings
Use is limited to intubated patients
Placement can cause damage to the oro/nasal pharynx
r/f inadvertent placement in the trachea
Caution in patients with a history of esophageal varices and/or gastric bypass surgery
How does pulse oximetry work?
based on the Beer-Lambert law, which relates the transmission of light transmitted and the concentration of solute, both within a solution.
In the case of pulse oximetry, the solute is hemoglobin, and solution is blood.
What kind of light does the pulse oximeter emit?
The pulse oximeter emits red and infrared light
Red light (660 nm) is absorbed by deoxyhemoglobin (higher in venous blood)
Infrared light (940 nm) is absorbed by oxyhemoglobin (higher in arterial blood)
SpO2 = oxygenated hemoglobin/(oxygenated Hgh + deoxygenated hgb) x 100
The closer the pulse ox monitor is to central circulation, the ____.
1) faster it will respond to arterial desaturation, and 2) more resistant to vasoconstrictive effects SNS stimulation and hypothermia
Fast: ear, nose, tongue, esophagus, forehead
Middle: finger
Slow: toes
Describe the clinical changes you’ll see with a left vs right oxyhemoglobin curve.
SpO2 values and their corresponding PaO2
SpO2 of 70% = PaO2 40 mm Hg
SpO2 of 80% = PaO2 50 mm Hg
SpO2 of 90% = PaO2 60 mm Hg
SpO2 of 100% = PaO2 70 - 100 mmHg
Strategies to improve pulse ox waveform
- Warm extremity
- Protect against ambient light
- Digital block
- Vasodilating cream
- Administer arterial vasodilator
Pulse oximetry is a noninvasive monitor of:
- Hemoglobin saturation
- Heart rate
- Fluid Responsiveness (pulse pressure variation)
Pulse oximeter is NOT a monitor of:
- Anemia
- Ventilation
- Bronchial intubation
Measuring perfusion with a mediastinoscopy
mediastinoscope is placed behind the thoracic artery, if the pulse oximeter is on the RIGHT extremity, the quality of the waveform may be influenced by compression of the brachiocephalic artery by the scope
Measuring perfusion in lithotomy position
leg perfusion, placement of pulse oximeter on the toe
Perfusion concerns for a fracture or shoulder arthroscopy?
Fracture – limb perfusion
Shoulder arthroscopy – brachial artery compression
What are the limitation of a pulse oximeter?
A pulse oximeter can accurately measure hgb and deoxygenated hgb but cannot accurately measure dysfuntional hgb, such as methemoglobin and carboxyhemoglobin
General Facts for Methemoglobin
Absorbs 660 nm and 940 nm equally
The 1:1 absorption ratio is read as 85%
Underestimates SpO2 at sat > 85%
Overestimates SpO2 at sat < 85%
What are some conditions that could alter a pulse ox reading?
Perfusion: vasoconstriction, hypothermia, hypoperfusion, Reynaud’s syndrome
Dyes: methylene blue, indigo carmine, nail polish;
Flow: CPB, LVAD;
Motion: patient moving, shivering
General Facts for Carboxyhemoglobin
Absorbs red light 660 nm to the same degree as O2-Hgb
CO-Hgb and O2-Hgb are interpreted as the same
Overestimates SpO2 by adding CO-Hgb and O2-Hgb
Facts for Capnography
Capnography measures end-tidal CO2 over time
CO2 is a byproduct of aerobic metabolism, ventilation is the process by CO2 is removed from the body
Capnography continuously monitors perfusion, metabolism and ventilation
“Phases” of Capnography
Phase I – Exhalation of anatomic dead space
Phase II - Exhalation of anatomic dead space + dead space
Phase III – Exhalation of alveolar gas
Phase IV – Inspiration of fresh gas that does not contain CO2
“Points” of Capnography
Point C - alpha angle – normally 100 degrees, an increase suggests an airflow obstruction (e.g. COPD, kinked tube)
Point D – Where end tidal CO2 is measured (normally 35 – 40 mmHg
Point D – beta angle – normally 90 degrees, an increase suggests rebreathing due to faulty unidirectional valves. Exhausted CO2 absorbent will have increase baseline normal beta angle
Potential Reasons for High End Tidal CO2
Increased BMR, Malignant hyperthermia, Thyrotoxicosis, Sepsis, Seizures, Laparoscopy, Tourniquet or vascular clamp removal, Anxiety, Pain, Shivering
Hypoventilation, CNS depression, COPD, Residual neuromuscular blockade, High spinal anesthesia, Neuromuscular disease
Rebreathing, CO2 absorbent exhaustion, Unidirectional valve malfunction, Leak in breathing circuit, Increased apparatus dead space
Potential Reasons for Low End Tidal CO2
Decreased BMR, Increased anesthetic depth, Hypothermia, Decreased pulmonary blood flow, Decreased cardiac output, Hypotension, Pulmonary embolism, V/Q mismatch
Hyperventilation, Inadequate anesthesia, Metabolic acidosis
Ventilator disconnect, Esophageal intubation, Poor seal with ETT or LMA , Sample line leak, Airway obstruction, Apnea
Progression of CO2 through the body to the circuit
- Metabolism produces CO2
- Perfusion transports CO2 in in the blood to the lungs
- Ventilation transports CO2 across the alveoli to the breathing circuit
- The sampling system containing CO2 is intact
How does a ventilator work? What is a ventilator mode?
Ventilators generate gas flow by creating a pressure gradient between the proximal airway and the alveoli.
A ventilator mode is a combination of control variable, breath sequence, and target scheme.
What is the control variable?
The control variable is the independent variable in the ventilator mode
Volume-controlled ventilation – volume is the independent variable and the waveform is specified.
Pressure-controlled ventilation - pressure is the independent variable and the waveform is specified.
Targetting scheme
Targeting scheme is a feedback control design to deliver a specific pattern.
A type of targeting scheme called set point targeting is the most basic. One sets a value, and ventilator seeks to deliver it.
For VCV, set points would be VT and flow.
For PCV, commonly it would be inspiratory pressure and inspiratory time.