In general, postoperative ventilation for up to 24 h does not cause major problems. Any opioid can be used with no significant advantages or disadvantages. Short-term mechanical ventilation
Short-acting opioids and benzodiazepones are the drugs of choice in patients with an expected duration of mechanical ventilation of up to 5 days. In these patients sufentanil may have pharmacological advantages over other opioids because of its lower cumulation tendency. Tolerance development and withdrawal symptoms may be less pronounced than with fentanyl. The weaning phase may be facilitated by administering clonidine. Regional analgesia is rarely used except in selected patients (e.g. severe pancreatitis).
The main problems during analgesia and sedation occur in patients who are ventilated for more than 5 days. Sepsis, acute respiratory distress syndrome, renal and liver failure, specific procedures such as the prone position, weaning problems, and sympathetic hyperactivity syndromes (e.g. withdrawal from chronic alcohol abuse) may significantly complicate the control of adequate analgesia and sedation. In general, there seems little sense in using ultra-short-acting substances in patients with an expected duration of treatment of several days or even weeks. Sufentanil may be an exception due to its higher affinity with the opioid receptor, lower tolerance development, and less pronounced withdrawal symptoms. Clonidine may be added if initial signs of tolerance development occur or even earlier to facilitate the control of analgesia and sedation. It should be also considered if sympathetic hyperactivity syndromes (agitation, tachycardia, hypertension) develop during the weaning phase. Administration of catecholamines is not a contraindication. If analgesia and sedation are insufficient despite high opioid and benzodiazepine doses, ketamine may be considered as an alternative in hemodynamically instable patients. However, despite neurophysiological advantages (NMDA antagonist) the high costs of ketamine may restrict its use in many ICUs.
During the weaning phase the analgesics and sedatives should be reduced slowly and continued into the postextubation phase. Hyperventilation may be titrated with low doses of opioids to the desired respiratory frequency.
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