Procedural Sedation and Analgesia (PSA) is the administration of sedatives and analgesics or dissociative anesthetics to induce a depressed level of consciousness while maintaining cardiorespiratory function so that a medical procedure can be performed with little or no patient reaction or memory.
PSA Terminology and levels of Sedation
Minimal sedation (anxiolysis): A drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular function is unaffected.
Moderate sedation (formerly conscious sedation): A drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. Reflex withdrawal from a painful stimulus is not considered a purposeful response. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained.
Deep sedation: A drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully after repeated or painful stimulation. The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining a patent airway, and spontaneous ventilation may be inadequate. Cardiovascular function is usually maintained.
Dissociative sedation: A trancelike cataleptic state induced by the dissociative agent ketamine and characterized by profound analgesia and amnesia with retention of protective airway reflexes, spontaneous respirations, and cardiopulmonary stability.
General anesthesia: A drug-induced loss of consciousness during which patients cannot be aroused, even by painful stimulation. The ability to independently maintain ventilatory function is often impaired. Patients frequently need assistance in maintaining a patent airway, and positive pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardio- vascular function may be impaired.
Evaluation before PSA
- ASA Grading
- Inspect Airway for difficulty (short neck, micrognathia, large tongue, trismus, morbid obesity, a history of difficult intubation, or anatomic anomalies of the airway and neck)
- Last Ate/Drank
- Systemic Disease (Most agents can cause vasodilatation and hypotension, particularly in patients with pre-existing hypovolemia)
- Medications
- Allergies
- Prior Sedation
- Estimated Weight
PSA ideally needs 2 Doctors and 1 Nurse
There is no evidence that the risk of aspiration during procedural sedation is increased with recent oral intake. Current guidelines regarding the safe fasting period prior to procedural sedation are based on expert consensus. Recent food intake is not an absolute contraindication. However, f the risk of aspiration is concerning, waiting 3 hours after the last oral intake before performing procedural sedation is associated with a low risk of aspiration, regardless of the level of sedation.
Equipment, Drugs and Preparation (Prepare as you do for Intubation)
- Suction/O2
- BMV
- OPA/NPA
- Laryngoscopes
- ET Tube/Stylet
- Bougie
- LMA
- Defibrillator
- Difficult Airway Equipment
- Analgesics (Fentanyl/Morphine/Ketamine/NO)
- Sedatives (Propofol, Midazolam, Etomidate)
- Anti-emetics
- Reversal Agents
- IV Fluids
Monitoring during PSA
Type of monitoring and Number of Providers
Interactive monitoring i.e. direct observation of the patient to assess the depth of sedation and observe for hypoventilation or apnea, upper airway obstruction, laryngospasm, vomiting, or aspiration.
Electronic monitoring i.e. using equipment to assess arterial oxygenation, ventilation, blood pressure, and cardiac rate and rhythm. Moderate and deep sedation require constant observation and continuous monitoring.
- Consciousness level
- Resp Rate and Effort
- ECG
- Blood Pressure
- SpO2
- ETCO2
Pulse oximetry is not a substitute for monitoring ventilation, as hypoventilation or apnea develop before oxygen saturation decreases, especially in patients who receive supplemental oxygen.
Ventilation can be electronically monitored using capnography. The end-tidal carbon dioxide correlates with the arterial partial pressure of carbon dioxide so that an end-tidal carbon dioxide above 50 mm Hg (6.6kPa) or an increase in end-tidal carbon dioxide >10 mm Hg (1.33 kPa) indicates hypoventilation. A flat-line capnogram can be due to apnea, upper airway obstruction, or complete laryngospasm. Normalization of the waveform after chin lift, jaw thrust, or oral airway placement confirms that apnea was due to upper airway obstruction. Capnography during procedural sedation allows the early recognition of adverse events. Because the risk of respiratory depression increases with the depth of sedation, capnography should be considered for moderate sedation and is recommended for prolonged deep sedation.
Sequence of Events
1. Give Analgesics (morphine/fentanyl) first.
2. Preoxygenate: Supplemental oxygen reduces the incidence of hypoxemia and has no adverse clinical effects. In morbidly obese patients, BiPAP may be useful to facilitate adequate sedation while averting hypoventilation. Connect appropriate monitoring equipment to the patient.
3. Give Sedative Agent
Once administered, observe and monitor the patient until the peak effect of the initial sedative dose has been reached. Once the patient has achieved the target sedation level, do the procedure and give additional doses in small increments if needed.
Once administered, observe and monitor the patient until the peak effect of the initial sedative dose has been reached. Once the patient has achieved the target sedation level, do the procedure and give additional doses in small increments if needed.
Complications
- Aspiration
- Hypoxia
- Hypotension
- Allergic Reaction
- Agitation
- Vomiting
- Delayed Recovery
Issues arise due to using an inappropriate agent or giving an incorrect dose or administering through a wrong route and poor use of adjunctive agents. Time of onset from injection to the initial observed effect must be appreciated bby the provider, especially when using drugs in combination, to avoid stacking of drug doses and oversedation.
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| Sample Discharge Instructions |
RCEM ED Sedation Proforma
Key Points
- Pulse oximetry measures the percentage of hemoglobin that is bound to oxygen and is not a substitute for monitoring ventilation because of the variable lag time between the onset of hypoventilation or apnea and a change in the oxygen saturation of hemoglobin molecules.
- The emotional state of a patient on induction strongly correlates with the degree of distress on emergence and in the days immediately after the procedure.
- There is no universally correct or preferred medication or drug regimen. Many options are acceptable and successful. The best choice is an agent whose pharmacologic properties are familiar to the operator and that is used frequently by the operator, is easily titratable, and has a short duration of action or is readily reversible.
- Clinicians must have a thorough knowledge of the pharmacokinetics, dosing, administration, and potential complications of the PSA agents that they use.
Posted by:
Lakshay Chanana
ST4 Trainee
Royal Infirmary of Edinburgh
Department of Emergency Medicine
Department of Emergency Medicine
Edinburgh
Scotland
Scotland
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