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.
What is breathing sequence?
Breath sequence is the pattern of mandatory and/or spontaneous breaths in a ventilator mode
Continuous spontaneous ventilation (CSV) is ______.
a sequence in which all breaths are spontaneous.
Intermittently mandatory ventilation (IMV) is ____.
a sequence in which spontaneous breaths are permitted in between mandatory breaths. If a mandatory breath is triggered by the patient, it a “synchronized” mandatory breath.
In continuous mandatory ventilation (CMV), ______.
all breaths (including those by patient effort) are mandatory.
Ventilation modes can be provider specific choice EXCEPT in these scenarios
- Patients who breathe rapidly on ACV should switch to SIMV
- Patients who have respiratory muscle weakness and/or left-ventricular dysfunction should be switched to ACV
Assist-Control Ventilation
The ventilator can be set for a fixed ventilatory rate, but each patient effort of sufficient magnitude will trigger the set tidal volume.
If spontaneous inspiratory efforts are not detected, the machine functions as if in the control mode.
The larger the set volume, the more expiratory time required.
If the I:E ratio is less than 1:2, progressive hyperinflation may result.
ACV is particularly undesirable for patients who breathe rapidly – they may induce both hyperinflation and respiratory alkalosis.
Synchronized intermittent mandatory ventilation
Synchronized intermittent mandatory ventilation (SIMV) times the mechanical breath to coincide with the beginning of a spontaneous effort and prevent breath stacking.
The frequency and VT of spontaneous breaths are determined by the patient’s ventilatory drive and muscle strength. IMV has found greatest use as a weaning technique.
Disadvantages of SIMV are increased work of breathing and a tendency to reduce cardiac output
The addition of pressure support on top of spontaneous breaths can reduce some of the work of breathing.
Pressure-Controlled Ventilation
Less risk of barotrauma as compared to ACV and SIMV.
Does not allow for patient-initiated breaths.
The inspiratory flow pattern decreases exponentially, reducing peak pressures and improving gas exchange.
The major disadvantage is that there are no guarantees for volume, especially when lung mechanics are changing.
Pressure Support Ventilation
Allows the patient to determine inflation volume and respiratory frequency (but not pressure), thus can only be used to augment spontaneous breathing.
Low levels of PSV (5–10 cm H2O) are usually sufficient to overcome any added resistance imposed by the breathing apparatus.
Higher levels (10–40 cm H2O) can function as a standalone ventilatory mode if the patient has sufficient spontaneous ventilatory drive and stable lung mechanics.
PSV can be delivered through specialized face masks.
Positive end-expiratory pressure (PEEP) is ____
a mechanical maneuver that increases functional residual capacity (FRC) and prevents collapse of the airways, thereby reducing atelectasis.
Pressure volume loops provide ____.
insight into lung compliance and show volume on a vertical axis and airway pressure on the horizontal axis
A more upright shows increased compliance in that greater volumes are achieved at lower pressures
Decreases in compliance can occur as a result of
pulmonary embolism, bronchoconstriction, pneumothorax, insufflation of the abdomen for laparoscopic surgery, or inadequate muscle relaxation
Flow-volume loops provide information on ____.
pulmonary resistance and show flow on the vertical axis and volume on the horizontal axis
Mild bronchospasm may cause slight changes in the flow-volume loop, but, as the spasm progresses, a decreased flow throughout exhalation can be seen.
Electroencephalogram general facts
- The EEG is a recording of electrical potentials generated by cells in the cerebral cortex.
- EEG activity occurs mostly at frequencies between 1 and 30 cycles/sec (Hz).
- EEG waves are also characterized by their amplitude
Describe the different waveforms seen on an EEG
Alpha waves (8 to 13 Hz) are found often in a resting adult with eyes closed.
Beta waves (13 to 30 Hz) are found in concentrating individuals, and at times, in individuals under anesthesia.
Delta waves (0.5 to 4 Hz) are found in brain injury, deep sleep, and anesthesia.
Theta waves (4–7 Hz) are also found in sleeping individuals and during anesthesia.
Bispectral index
Device designed to reduce the incidence of awareness during general anesthesia, process two-channel EEG signals and create a dimensionless variable to indicate level of wakefulness. Controversial.
The bispectral index (BIS) is most commonly used in this regard and is a dimensionless scale from 0 (complete cortical electroencephalographic suppression) to 100 (awake).
BIS values of 65–85 have been recommended for sedation, whereas values of 40–65 have been recommended for general anesthesia. At BIS values lower than 40, cortical suppression becomes discernible in a raw electroencephalogram as a burst suppression pattern.
Checklist for Awareness
- Check all equipment, drugs, and dosages; ensure that drugs are clearly labeled and that infusions are running into veins.
- Consider administering an amnesic premedication.
- Avoid or minimize the administration of muscle relaxants. Use a peripheral nerve stimulator to guide minimal required dose.
- Choose potent inhalation agents rather than total intravenous anesthesia, if possible.
- Administer at least 0.7 minimum alveolar concentration (MAC) of the inhalation agent.
- Set an alarm for a low anesthetic gas concentration.
- Monitor anesthetic gas concentration during cardiopulmonary bypass from the bypass machine.
- Consider alternative treatments for hypotension other than decreasing anesthetic concentration.
- If it is thought that sufficient anesthesia cannot be administered because of concern about hemodynamic compromise, consider the administration of benzodiazepines or scopolamine for amnesia.
- Supplement hypnotic agents with analgesic agents such as opioids or local anesthetics, which may help decrease the experience of pain in the event of awareness.
- Consider using a brain monitor, such as a raw or processed electroencephalogram but do not try to minimize the anesthetic dose based on the brain monitor because there currently is insufficient evidence to support this practice.
- Monitor the brain routinely if using total intravenous anesthesia.
- Evaluate known risk factors for awareness, and if specific risk factors are identified consider increasing administered anesthetic concentration.
- Re-dose intravenous anesthesia when delivery of inhalation anesthesia is difficult, such as during a long intubation attempt or during rigid bronchoscopy.
- If awareness is suspected, reassure the patient while increasing anesthetic depth
Use of the Brice questions during postoperative visits can identify a potential awareness event. Ask patients to recall the following:
- What do you remember before going to sleep?
- What do you remember right when awakening?
- Do you remember anything in between going to sleep and awakening?
- Did you have any dreams while asleep?
Close follow-up and involvement of mental health experts may avoid the traumatic stress that can be associated with awareness events
Patients undergoing regional anesthesia should be made aware of ___
the fact that they are not receiving general anesthesia and may recall perioperative events
What are indications for intraoperative monitoring of evoked potentials?
How are they monitored?
Indications for intraoperative monitoring of evoked potentials (EPs) include surgical procedures associated with possible neurological injury
EP monitoring noninvasively assesses neural function by measuring electrophysiological responses to sensory or motor pathway stimulation.
Waveforms are analyzed throughout surgery for latency and peak amplitude, changes may suggest acquired injury to neural pathway during surgery
Persistent obliteration of EPs is predictive of ____.
postoperative neurological deficit.
Commonly monitored EPs are _____.
brainstem auditory evoked responses (BAERs), SEPs, and increasingly, MEPs.
The SEP is produced by stimulation of a peripheral nerve wherein a response can be measured, and the MEP is produced by stimulation of the motor cortex.
How do total anesthetic techniques affect evoked potentials?
Total intravenous anesthetic techniques (with or without nitrous oxide) cause minimal changes to EPs, whereas volatile agents are best avoided or used at a constant low concentration.
Hypothermia is associated with ____.
delayed drug metabolism, increased blood glucose, vasoconstriction, impaired coagulation, postoperative shivering accompanied by tachycardia and hypertension, and increased risk of surgical site infections.
Hyperthermia can lead to ___.
tachycardia, vasodilation, and neurological injury.
Key Points of Esophageal, nasopharynx, rectum and bladder temperature monitoring
- esophagus- best measured in the 1/3rd and 1/4th of the esophagus. Will be increased if placed in the stomach due to heat created by liver metabolism. Decreased if measured in the proximal esophagus due to cool inspiratory gas.
- Nasopharynx- less reliable than the esophageal temp. Decreased if leakage of inspiratory gas.
- Rectum- Risk of bowel perforation. Increased by heat producing bacteria in the gut. Decreased by cool blood from the lower extremities and insulated by stool.
- Bladder- Risk of urinary tract infection. Decreased if inadequate UOP.
Pulmonary artery, tympanic membrane, and skin temperature monitoring
- Pulmonary artery- requires a PA catheter. Decreased if open chest procedure.
- Tympanic membrane- Risk of tympanic membrane injury
- Does not correlate with core temp (only measures specific region of the skin)
Sources of heat loss
Radiation (infared) = 60%. #1 Source of heat loss. Heat follows a temp gradient, if the patient is warmer than the environment, then heat is lost to the environement in the form of infared radiation. Most lost through skin. Cover the patient.
Convection (Air) 15-30%. Transfer of heat by movement of matter. Laminar flow increases the amount of heat lost to convection.
Evaporation (water loss) 20%. Takes significant amount of energy to vaporize water. The rate of this process is a function of the exposed surface area and relative humidity of the environment. Water is lost by evaporation from respiration, wounds, and exposure of internal organs during surgery.
Conduction (contact) <5%. Pt comes into direct contact with a cooler object. Ex. = OR table, IV fluids, and irrigation fluids
Stages of Heat Loss (Phase 1)
- With general, spinal or epidural anesthesia, there is redistribution of heat from thorax (central) to extremities (peripheral)
- General anesthetics impair thermoregulatory response in hypothalamus, prevent shivering and cause vasodilation
- Heat redistribution is WAY more important than heat loss in phase 1
- Interventions= warm blanket before patient enters OR
Stages of Heat loss Phase 2
Heat loss to the environment exceeds heat production
Stages of Heat Loss (Phase 3)
equilibrium develops between heat loss to the environment and heat production
Urinary Output Considerations
- catheterization is the most reliable method of monitoring urinary output.
- Catheterization is routine in some complex and prolonged surgical procedures (over 2 hours)
- Catheterization is indicated = difficulty voiding in the PACU or after general or regional anesthesia
- Foley should be removed as soon as feasible to avoid the risk of catheter-associated urinary tract infections
- Urinary output is an imperfect reflection of kidney perfusion and function and of renal, cardiovascular, and fluid volume status.
- helpful neuraxial anesthesia
Electrocardiogram (General)
- (ECG) is a requirement for any patient receiving an anesthetic.
- Heart rate, rhythm, and, for some patients, ST segments and T waves.
- Approximately ⅓ of patients scheduled for noncardiac surgery have risk factors for coronary artery disease (CAD), and postoperative myocardial infarction (MI) is three times as frequent in patients with ischemia compared to patients without ischemia.
- The overall incidence of perioperative ischemia in patients with CAD scheduled for cardiac or noncardiac surgery ranges from 20% to 80%.
Electrocardiogram (General)
- Most commonly monitored leads are II and V5
- Use monitor rhythm because provides P wave
- V5 monitors for anterior and lateral ischemic events
- If you are unable to use ECG for any reason document it based on AANA standards
P Wave
- Duration- 0.06-0.12 seconds
- Amplitude < 2.5
- Prolonged with first Degree block
PR Interval
- Duration- 0.12-0.20 seconds
- Pericarditis- PR interval depression
Q Wave
- Duration- <0.04 seconds
- Amplitude- <0.04-0.05 seconds
- Consider MI if: Amplitude is greater than ⅓ of R wave, Duration is greater than 0,04 seconds, Depth is greater than 1mm
QRS Complex
- Duration- <0.10 seconds
- Amplitude- Progressively 1’s from V1-V6- normal R wave Progression
- If increased consider- LVH, BBB, ectopic beat, WPW
QTc Interval
- Duration- Men: <0.45 Women: <0.47
ST Segment
Consider MI if:
- Elevation or depression is greater than 1 mm
- elevation can also be caused by hyperkalemia or endocarditis
T Wave
- Amplitude- <10 seconds in precordial leads, <6 in limb leads
- Considerations: Usually T wave points in same direction as QRS
- T wave in opposite direction= prolonged depolarization (MI, BBB)
- Peaked T waves= MI, LVH, intracranial bleed
Where to measure ST Changes
- reference point= PR segment
- J point is where QRS complex ends and the ST segment begins ( + 1 or -1 is significant)
- Degree of ST changes correlates with severity of event
Blood Pressure
- Korotkoff sounds: SPB – 1st sound, DBP – 2nd sound
- The oscillatory method is used by automated NIBP machines
- SBP – measured when oscillations appear first
- MAP – measured when oscillations are greatest
- DBP – measured when oscillations are least but still appreciable
Complications of Blood Pressure
- Pain
- Neuropathy
- Limb Ischemia
- Compartment Syndrome
- Bruising
- Interference with IV medications if IV is distal to the cuff
Where NOT to place a BP cuff
- PICC line
- Bone fractures
- Surgical site
- Limb with AV fistula
Factors that Influence BP Cuff
- NIBP cuff too small – BP falsely elevated
- NIBP cuff too large – BP falsely low
- Cuff location-As blood travels through arteries, SBP increases, DBP decreases, pulse pressure widens, and MAP remains constant
- At the aortic arch – SBP is lowest, DBP is highest, and PP is narrowestAt the dorsalis pedis – SBP is highest, DBP is lowest, and PP is wides
- Arm position- NIBP cuff above the heart – BP reading is falsely decreased
- NIBP cuff below the heart – BP reading is falsely elevated
- For every inch change, the BP changes 2 mmHg
SLIDE 52 A-Line Wave form
Please review, not sure how to add a picture :)
Central Venous Catheter
- CVC – the catheter tip should be just above where the vena cava connects to the right atrium
- PA catheter – should reside in the pulmonary artery, distal to the pulmonic valve (25-35 cm from the VC junction)
- If you are not obtaining the expected waveform during incremental advancement, the PA catheter could be coiled. Deflate the balloon, withdraw to the VC/RA junction, and retry. If there is resistance on withdrawal, the PA catheter could be knotted or entangled, obtain chest x-ray to assess.
Central Line Complications
- Obtaining Access
- Arterial puncturePneumothorax
- Air embolism
- Neuropathy
- Catheter know
Catheter Residence
- Bacterial colonization of catheter
- Bacterial colonization of heart or pulmonary artery
- Sepsis
- Thrombus formation
- Thrombophlebitis
Floating PA catheter
- Pulmonary artery rupture
- Right bundle branch block
- Complete heart block (with preexisting LBB)Dysrhythmias
Central Line Catheter Pearls
- L IJ access – r/f puncturing thoracic duct
- Treatment of arrythmias may include withdrawing catheter
- LBBB is a contraindication to a PA catheter
- r/f CVC infections increases after three days
- Pulmonary artery rupture risk is increased with anticoagulation, inserting the catheter too far, and prolonged balloon inflation; and often presents with hemoptysis
Normal CVP Waveform
- A Wave- Right atrial contraction, just after P wave (atrial depolarization)
- C Wave- Right ventricular contraction (bulging of tricuspid valve into RA), Just after QRS (ventricular depolarization)
- X descent- RA relaxation, ST Segment
- V Wave- Passive filling of RA, just after T wave begins (ventricular repolarization)
- Y descent- RA empties through open tricuspid valve, after T wave ends
Please reference image in slides :)
CVP Abnormal Waveform- Loss of A or V Waves
- Atrial fibrillation
- Ventricular pacing in the setting of asystole
CVP Abnormal Waveform- Giant A or “Cannon” A Waves
- Junctional rhythms
- Complete AV block
- PVC’s
- Ventricular pacing (asynchronous)
- Tricuspid or mitral stenosis
- Diastolic dysfunction
- myocardial ischemia
- Ventricular hypertrophy
CVP Abnormal Waveform- Large V Waves
- Tricuspid or Mitral regurgitation
- acute increase of intravascular volume
Normal CVP Reading
CVP reading with large V waves
CVP reading with loss of A waves
CVP reading with Cannon waves
