Analgesia, Local Anesthesia


SEDATION


=  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


Sedatives


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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