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Opioids modulate nociception at the terminals of afferent nerves in the
CNS, peripheral nervous system, and GI tract.
Opioids are agonists at the 3 primary opioid receptors:
µ (mu), κ (kappa), and δ (delta).
µ-receptors : analgesia, sedation, miosis, respiratory depression, cough suppression,
euphoria, and decreased GI motility
All currently available opioid agonists possess µ-receptor activity
所以都會造成不同程度呼吸抑制
Codeine, morphine, heroin : 驗尿 2-4 天內陽性
The oxycodone, fentanyl, and methadone-specific screens can be positive up to 3 days after ingestion.
Miosis : not universally present from intoxication with every opioid
Lethargy
Respiratory depression : Hypercarbia, Hypoxia, Cyanosis
Opioid intoxication include :
- Orthostatic hypotension
- Nausea and vomiting (especially in opioid-naive patients)
- Histamine release resulting in localized urticaria
- Bronchospasm
- Ileus secondary to decreased GI motility
- Urinary retention secondary to increased vesical sphincter tone
Hypothermia, rhabdomyolysis, compartment syndrome, myoglobinuric renal failure,
and seizures associated with overdoses of tramadol and meperidine
- Opioid-induced acute lung injury (noncardiogenic pulmonary edema)
10% in patients with severe overdose requiring naloxone
Additional naloxone, diuretics, and digoxin are not indicated.
- Meperidine, tramadol, or dextromethorphan with MOAI, SSRI, or linezolid can result in serotonin syndrome
Naloxone is not effective in treating opioid-induced serotonin syndrome
Airway protection and ventilatory assistance
The goal of naloxone administration is NOT a normal level of consciousness,
but adequate ventilation
After adequate ventilation is ensured, administer naloxone
AILS 還是可以給活性碳洗胃
Single-dose activated charcoal (1 g/kg PO) may be indicated or multiple doses of activated charcoal
Naloxone : 0.4 mg / ml / amp
Pure competitive antagonist at all opioid receptors, with particular affinity for μ-receptors.
Naloxone fully reverses all the effects of opioids,
including respiratory depression, sedation, miosis, and analgesia
使用的效果決定於需要反轉的嗎啡量 + 必須衡量 withdrawal 風險
* * 慢性使用者, 病人意識不好但還有自呼 : 謹慎地從 0.04 mg 開始
* * 不像慢性使用者, 意識不好但還有自呼 : 0.4 mg IV
之後 0.04 - 0.4 mg IV every 2 to 3 minutes until the desired effect is reached
慢慢上調減少 opioid withdrawal 發生
Incremental dosing of naloxone mitigates the precipitation of acute opioid withdrawal
* * Apnea or near-apnea and cyanosis : 2 mg
之後每 3 分鐘補 2mg 直到症狀緩解或達到上限 10 mg
Fentanyl, novel synthetic opioids, sustained-release preparations, body packers :
large and sustained naloxone
Certain long-acting opioids, such as buprenorphine and methadone :
有時需要 Naloxone infusions
因為 naloxone half life 比這些長效 opioid 短
To calculate the naloxone continuous infusion dose,
determine the “wake-up dose” and administer two thirds of that dose per hour by IV infusion.
Naloxone 很安全, 對 opioid-naive patients 沒什麼不良反應
Anxiety, nausea, vomiting, diarrhea, abdominal cramps, piloerection, yawning, and rhinorrhea,
which are expected signs and symptoms of opioid withdrawal.
Naloxone, if given in single large-dose bolus,
may precipitate opioid withdrawal in opioid-dependent patients
causing patient distress and life threatening complications :
seizures, non-cardiogenic pulmonary edema, and cardiovascular collapse.
AILS : 0.4-0.8 mg IV, 一次劑量不超過 2 mg
五分鐘沒效可以再給一次, 兩次給藥無效則可能要考慮其他原因
記 : 台灣就給 1 amp ~
也有氣管內管給藥, 屬於非適應症途徑, 劑量要IV的 2-2.5 倍, 約 0.8 - 5 mg
https://www.facebook.com/icuteaching/posts/1304517656314861
Naltrexone, Nalmefene : oral and parenteral opioid antagonist,
maintain opioid abstinence after detoxification
Opioid withdrawal
長期使用 opioids -> Downregulation of endogenous endorphins and opioid receptors
Abrupt cessation of opioid use does not allow time for upregulation of receptors
and results in increased neuronal firing and the opioid withdrawal syndrome.
Opioid withdrawal 發生時間 :
- 6 - 12 hours after last use of short-acting opioids
- 30 hours after abstinence from long-acting opioids.
Opioid withdrawal 很不舒服
but not life-threatening and rarely fatal
Goose bumps (Piloerection)
Symptomatic therapy, usually antiemetics and antidiarrheals
Central α 2 -agonist (Clonidine) should not be used if the patient is hypotensive or bradycardiac.
No methadone or buprenorphine should be administered
to an opioid-dependent patient until withdrawal symptoms appear.
Opioid replacement therapy, usually with buprenorphine or methadone,
should be considered for moderately severe withdrawal and is recommended for severe withdrawal
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