EFFECT OF LONG-TERM SEDATION ON INTESTINA L FUNCTION IN MECHANICALLY VENTILATED, CRITICALLY ILL PATIENTS

Gastrointestinal integrity with intact function are of main importance in critically ill patients, and not only as a route of nutritional su pport. Drugs used for long-term sedation can lead to disordered gastro intestinal motility. In this study we compared the influence of differ ent combinations of analgesics and sedatives on the intestinal functio n in mechanically ventilated, critically ill patients. Methods. A tota l of 190 patients were evaluated retrospectively. All patients require d controlled mechanical ventilation and deep sedation (Ramsay Score 5- 6) for 7 days or more due to acute respiratory failure or elevated int racranial pressure. In none of these patients was enteric tube feeding contraindicated. Intact intestinal function was assumed when full ent eric tube feeding was achieved on days 5 and 6 of the treatment period . Furthermore, other gastrointestinal motility disorders (e.g. constip ation) had to be absent. In all patients the feeding tube was placed i n the stomach by the nasogastric route. Corresponding to different com binations of analgesics and sedatives, the 190 patients were divided i nto 11 groups The following combinations were used: group 1 (n=20), fe ntanyl + flunitrazepam; group 2 (n=20), fentanyl + midazolam; group 3 (n=20), fentanyl + thiopentone; group 4 (n=20) piritramide + midazolam ; group 5 (n=20), piritramide and continuous epidural administration o f bupivacaine + midazolam; group 6 (n=20), piritramide + gamma-aminobu tyric acid (GABA); group 7 (n=20), ketaminei-midazolam; group 8 (n=10) , ketamin + methohexitone; group 9 (n=20), ketamine + propofol; group 10 (n=10), ketamine + midazolam acid GABA; group 11 (n=10) sufentanil + midazolam and methohexitone. Patients in groups 3, 8, 9, 10, and 11 all had severe head injury and elevated intracranial pressure. Group 6 was made up exclusively of elderly patients (>65 years) without head trauma. Results. The patients in groups 1, 2, and 3 received fentanyl for analgesia and were completely fed by enteric tube in 30%, 35%, and 15% of cases, respectively. In group 3 deep sedation was necessary be cause of elevated intracranial pressure. In groups 4, 5, and 6, piritr amide was administered for analgesia, and normal enteric tube feeding was achieved in 70%, 75%, and 90% of cases. The best results were seen in group 6, and these elderly patients needed smaller amounts of piri tramide for analgesia. In groups 7, 8, 9, and 10, ketamine was given f or analgesia, and complete enteric tube feeding was carried out in 75% , 30%, 45%, and 60% of these patients. The best results in the ketamin e groups were found in combination with midazolam as the sedating drug ; however, the patients in group 7 did not have elevated intracranial pressure, in contrast to the patients in groups 8, 9, and 10. The last group received the: combination of sufentanil, midazolam and methohex itone to achieve a deep sedation. The rate of normal enteric tube feed ing in these patients with severe head trauma was 30%. Conclusions. In patients with severe head trauma who need deep sedation to prevent da ngerous high intracranial pressure, gastrointestinal motility disorder s are very commonly found. The results obtained suggest that ketamine should be regarded as the analgesic drug of choice, combined with prop ofol rather than a high-dose barbiturate therapy. The combination of k etamine with midazolam and GABA is an unusual strategy for long-term s edation, which resulted from our own clinical studies directed at an e ffective and well-tolerated regime for this high-risk patient group. O bviously, high-dose barbiturates and short-acting opiolds, especially when combined, make enteric tube feeding more difficult. Therefore, we recommend piritramide or ketamine for analgesia. The basic sedating d rug is midazolam, in special cases combined with or replaced by propof ol. The position of GABA in long-term sedation is not yet clear, but a lack of side effects on the gastrointestinal tract became evident in this study. Finally, it should be emphasized that the feeding tube was placed in the stomach in all patients in this study. As failure to ac hieve an adequate intake with enteric tube feeding is often due to gas troparesis, better results might be achieved if tubes were placed in e ither the duodenum or the jejunum.