Analgesia, Local Anesthesia


=  administration of medication to calm the nervous system: ⇓ awareness; ⇓ responsiveness to external stimuli; ⇓ anxiety; ⇓ spontaneous movements; may produce amnesia

Phases of sedation protocol:   1. Preprocedural assessment

  2. Intraprocedural monitoring

  3. Postprocedural monitoring

Presedation Assessment

1.   Evaluate patient (within 30 days of procedure + update within 24 hours)

(a)  personal history:

›  cardiovascular: hypertension, myocardial infarction within prior 6 months, CHF, arrhythmia → pose an increased risk

›  respiratory: asthma, COPD, other lung disease

›  gastrointestinal: GERD, peptic ulcer, nil per os (NPO) status

›  fasting status: predictor of aspiration

◊  In an emergent procedure administer 10 mg IV metoclopramide (Reglan®) + 10 mg IV famotidine (Pepcid®) / other H2 blocker!

(b)  medication history

›  continue cardiovascular medication

›  monitor blood sugar in diabetics

(c)  physical examination

2.   Classify physical status of patient (see table)

3.  Document discussion with patient concerning risks and benefits + obtain consent

4.   Document plan for sedation

Dose adjustment:

›  in elderly 30–50% dose reduction + more frequent dose intervals

›  decrease dose with impaired kidney / liver function

›  habitual users of opioids / benzodiazepines require higher doses

Convert to monitored anesthesia (= supervision by anesthesiologist) if:

(a)  sedation cannot be administered safely (eg, Pickwickian syndrome, sleep apnea)

(b)  deep sedation is required

5.   Assure presence of appropriate personnel + equipment

6.   Identify correct patient immediately before onset of procedure

Intraprocedural Monitoring

1.   Respiratory rate: continuous monitoring with pulse oximetry

2.   ECG: continuous monitoring

3.   Blood pressure: every 5 min + before every dose

4.   Assessment of Alertness

5.  Pain assessment: verbal descriptor, linear numeric, face-pain scale

Postprocedural Monitoring

=  monitoring for postprocedural complications as drugs are unopposed by anxiety and pain related to procedure → deepening of sedation + respiratory depression

Frequency:   in 15-minute intervals for ≥ 30 minutes after last dose; for ≥ 2 hours after use of reversal agent


A.  Benzodiazepines

Action:   facilitate actions of g-aminobutyric acid (= main inhibitory neurotransmitter) in CNS; synergistic with opioids

Properties:   anxiolytic, amnestic

1.   Midazolam (Versed®)

Administration:   IM, IV (rapid onset of action)

Elimination half-life:   1–4 hours (short)

2.   Lorazepam (Ativan®)

Administration:   PO, IM, IV (variable peak effect)

Elimination half-life:   mean of 15 hours

3.   Diazepam (Valium®): also anticonvulsant

Elimination half-life:   20–100 hours

Administration:   PO, IM, IV (painful)

B.  Diphenhydramine (Benadryl®)

Action:   blocks histamine-1 receptors (H1 blocker); anticholinergic

Contraindication:   asthma, narrow-angle glaucoma, urinary retention

Side effect:   dry mouth, dizziness, sedation

Reversal Agents

=  drugs counteracting effects of drugs used for anesthesia

Assessment:   patient difficult to arouse, cardiorespiratory depression (= oxygen desaturation, drop in blood pressure)

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Jun 29, 2017 | Posted by in GENERAL RADIOLOGY | Comments Off on Analgesia, Local Anesthesia

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