Anesthesia for pediatric external beam radiation therapy.

Fortney JT, Halperin EC, Hertz CM, Schulman SR.

Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA.

BACKGROUND: For very young patients, anesthesia is often required for radiotherapy. This results in multiple exposures to anesthetic agents over a short period of time. We report a consecutive series of children anesthetized for external beam radiation therapy (EBRT). METHODS: Five hundred twelve children < or = 16 years old received EBRT from January 1983 to February 1996. Patient demographics, diagnosis, anesthesia techniques, monitoring, airway management, complications, and outcome were recorded for the patients requiring anesthesia. RESULTS: One hundred twenty-three of the 512 children (24%) required 141 courses of EBRT with anesthesia. Anesthetized patients ranged in age from 20 days to 11 years (mean 2.6 +/- 1.8 ). The frequency of a child receiving EBRT and requiring anesthesia by age cohort was: < or = 1 year (96%), 1-2 years (93%), 2-3 years (80%), 3-4 years (51%), 4-5 years (36%), 5-6 years (13%), 6-7 years (11%), and 7-16 years (0.7%). Diagnoses included: primary CNS tumor (28%), retinoblastoma (27%), neuroblastoma (20%), acute leukemia (9%), rhabdomyosarcoma (6%), and Wilms' tumor (4%). Sixty-three percent of the patients had been exposed to chemotherapy prior to EBRT. The mean number of anesthesia sessions per patient was 22 +/- 16. Seventy-eight percent of the treatment courses were once daily and 22% were twice daily. Anesthesia techniques included: short-acting barbiturate induction + inhalation maintenance (21%), inhalation only (20%), ketamine (19%), propofol only (12%), propofol induction + inhalation maintenance (7%), ketamine induction + inhalation maintenance (6%), ketamine or short-acting barbiturate induction + inhalation maintenance (6%). Monitoring techniques included: EKG (95%), O2 saturation (93%), fraction of inspired O2 (57%), and end-tidal CO2 (55%). Sixty-four percent of patients had central venous access. Eleven of the 74 children with a central line developed sepsis (15%): 6 of the 11 were anesthetized with propofol (55%), 4 with a short-acting barbiturate induction plus inhalation maintenance (36%), and 1 with inhalation alone (9%). Eight of the 11 (73%) received prior chemotherapy. CONCLUSION: Anesthesia was generally necessary at < or = 3 years, and rarely required at > 5 years of age. Sepsis associated with frequent use of the central venous access line was seen in 15% of the patients with these lines.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10348288&dopt=Abstract barbiturate Butalbital Fioricet





[Barbiturate withdrawal syndrome: a case associated with the abuse of a headache medication]

[Article in Italian]

Sarrecchia C, Sordillo P, Conte G, Rocchi G.

Cattedra di Malattie Infettive, Universita degli Studi Tor Vergata di Roma.

Barbiturates can produce psychological and physical dependence and produce a withdrawal syndrome on the second to fourth day after the drug is suspended. Symptoms include anxiety, restlessness, insomnia, rhythmic intention tremor, dizziness, seizures, and psychosis. If the syndrome is not recognized and correctly treated, hyperthermia, circulatory failure, and death may ensue. Although barbiturates are less frequently used nowadays, they are employed in combination with other drugs in many medications used for the treatment of headache. We report the case of a 54-year-old woman who developed a barbiturate abstinence syndrome when she suspended self-administration of a drug containing butalbital. The patient had been using barbiturates, 900 mg/die, for 2+ years for persistent headache. She was admitted to the hospital because of seizures, hallucinations and delirium not controlled by benzodiazepine and phenothiazine administration. Her symptoms resolved after parenteral phenobarbital administration.

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Depressant and convulsant barbiturates both inhibit neuronal nicotinic acetylcholine receptors.

Watanabe I, Andoh T, Furuya R, Sasaki T, Kamiya Y, Itoh H.

Department of Anesthesiology, Yokohama City University School of Medicine, Yokohama, Japan.

Neuronal nicotinic acetylcholine receptors (neuronal nAchRs) are sensitive to many anesthetics, including barbiturates, which suggests that these receptors are potential sites for anesthetic action. Subtle changes in molecular structures of the anesthetic barbiturates can produce compounds with potent convulsant activity. Whereas R(-) isomer of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) exerts anesthetic action, S(+)MPPB exhibits pure excitatory effects, including convulsion. 5-(2-cyclohexilidene-ethyl)-5-ethyl barbituric acid is another example of a convulsant barbiturate. We compared the effects of depressant and convulsant barbiturates on the neuronal nAchR-mediated current to determine whether inhibition of neuronal nAchRs contributes to the anesthetic action of barbiturates. Whole cell nicotine-induced currents were recorded in PC12 derived from rat pheochromocytoma, using the conventional whole cell patch clamp technique in the presence and absence of barbiturates. Both depressant and convulsant barbiturates inhibited the nicotine-induced inward current reversibly and in a dose-dependent manner when co-applied with nicotine. All barbiturates accelerated the current decay. There was no significant difference between the concentrations for 50% inhibition for MPPB isomers. There was no correlation between inhibition of ganglionic nAchRs and anesthetic effects of the barbiturates. These results strongly oppose the idea that inhibition of neuronal nAchRs contributes to the anesthetic action of barbiturates. IMPLICATIONS: We found that both convulsant and depressant barbiturates inhibit the current mediated through ganglionic nicotinic acetylcholine receptors in PC12 cells. This finding suggests that the inhibition of neuronal nicotinic acetylcholine receptors does not contribute to the anesthetic action of barbiturates.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10357353&dopt=Abstract barbiturate Butalbital Fioricet





Comparison of the effects of convulsant and depressant barbiturate stereoisomers on AMPA-type glutamate receptors.

Kamiya Y, Andoh T, Furuya R, Hattori S, Watanabe I, Sasaki T, Ito H, Okumura F.

Department of Anesthesiology, Yokohama City University School of Medicine, Japan.

BACKGROUND: Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system. Although barbiturates have been shown to suppress the AMPA receptor-mediated responses, it is unclear whether this effect contributes to the anesthetic action of barbiturates. The authors compared the effects of depressant [R(-)] and convulsant [S(+)] stereoisomers of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) on the AMPA and gamma-aminobutyric acid type A (GABA(A)) receptor-mediated currents to determine if the inhibitory effects on AMPA receptors correlate to the in vivo effects of the isomers. METHOD: The authors measured whole-cell currents in the rat cultured cortical neuron at holding potential of -60 mV. Kainate 500 microM was applied as the agonist for AMPA receptors. Thiopental (3-300 microM), R(-)-MPPB or S(+)-MPPB (100-1,000 microM) was coapplied with kainate under the condition in which the GABA(A) receptor-mediated current was blocked. Effects of MPPB isomers on the current elicited by GABA 1 microM were studied in the separate experiments. RESULTS: Thiopental inhibited the kainate-induced current reversibly and in a dose-dependent manner, with a concentration for 50% inhibition of 49.3 microM. Both R(-)-MPPB and S(+)-MPPB inhibited the kainate-induced current with a little stereoselectivity. R(-)-MPPB was slightly but significantly more potent than S(+)-MPPB. In contrast, R(-)-MPPB enhanced but S(+)-MPPB reduced the GABA-induced current. CONCLUSIONS: Both convulsant and depressant stereoisomers of the barbiturate inhibited the AMPA receptor-mediated current despite of their opposite effects on the central nervous system in vivo. Although thiopental exhibited a considerable inhibition of AMPA receptors, the results suggest that the inhibition of AMPA receptors contributes little to the hypnotic action of the barbiturates.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10360870&dopt=Abstract barbiturate Butalbital Fioricet