摘要:

BackgroundNeuronal excitation may result from stimulation of [Greek small letter gamma]‐aminobutyric acid A (GABAA) receptors that prolong the channel opening, depolarizing the postsynaptic membrane. Drugs such as acetazolamide or amiloride can block GABA depolarization. Barbiturates facilitate nociceptive reflexes and also prolong the GABAAchannel open‐time. To evaluate the possible mechanism, the authors studied the impact of acetazolamide and amiloride on pentobarbital‐induced nocifensive reflex facilitation. Because nitric oxide (NO) is a mediator of reflex facilitation, the authors evaluated the effects of NO synthase inhibition.MethodsNocifensive reflex thresholds were quantified with the hind paw withdrawal latency from radiant heat (HPW latency) in the rat. Nocifensive reflexes were facilitated with intraperitoneal injection of pentobarbital (30 mg/kg). The authors tested the roles of GABA‐mediated depolarization and NO in reflex facilitation by pretreatment with acetazolamide and amiloride and inhibition of NO synthase with L‐NAME and 7‐NI, respectively. Sedative effects of pentobarbital were evaluated with the righting reflex, the response to vibrissal stimulation, and plasma drug concentrations.ResultsPentobarbital decreased the hind paw withdrawal latency from 11.2 +/− 1 to 8.3 +/− 1 s (P < 0.001). Pretreatment with each of the four test drugs limited the reduction in reflex facilitation after pentobarbital to 1.3 s or less, similar to the reduction seen after saline injection, without altering sedation. L‐NAME increased plasma pentobarbital concentrations by 10% without changing the concentration associated with return of responsiveness.ConclusionsPentobarbital‐induced nocifensive reflex facilitation was inhibited by all four tested drugs without evidence of increased sedation. The results are consistent with a role for GABAAreceptor‐mediated depolarization in barbiturate‐induced hyper‐reflexia.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundIn cardiac myocytes, lidocaine reduces but mexiletine increases adenosine triphosphate (ATP)‐sensitive K+currents, suggesting that these class Ib antiarrhythmic drugs may differentially modify the activity of ATP‐sensitive K+channels. The effects of lidocaine and mexiletine on arterial relaxations induced by K+channel openers have not been studied. Therefore, the current study was designed to evaluate whether lidocaine and mexiletine may produce changes in relaxations to the ATP‐sensitive K+channel openers cromakalim and pinacidil in isolated rat thoracic aortas.MethodsRings of rat thoracic aortas without endothelia were suspended for isometric force recording. Concentration‐response curves were obtained in a cumulative fashion. During submaximal contractions to phenylephrine (3 x 10 (‐7) M), relaxations to cromakalim (10‐7to 3 x 10‐5M), pinacidil (10‐7to 3 x 10‐5M), or diltiazem (10‐7to 3 x 10 (‐4) M) were obtained. Lidocaine (10‐5to 3 x 10‐4M), mexiletine (10‐5to 10‐4M) or glibenclamide (5 x 10‐6M) was applied 15 min before addition of phenylephrine.ResultsDuring contractions to phenylephrine, cromakalim and pinacidil induced concentration‐dependent relaxations. A selective ATP‐sensitive K+channel antagonist, glibenclamide (5 x 10‐6M), abolished these relaxations, whereas it did not alter relaxations to a voltage‐dependent Ca (2+) channel inhibitor, diltiazem (10‐7to 3 x 10‐4M). Lidocaine (more than 10‐5M) significantly reduced relaxations to cromakalim or pinacidil in a concentration‐dependent fashion, whereas lidocaine (3 x 10‐4M) did not affect relaxations to diltiazem. In contrast, mexiletine (more than 10‐5M) significantly augmented relaxations to cromakalim or pinacidil. Glibenclamide (5 x 10‐6M) abolished relaxations to cromakalim or pinacidil in arteries treated with mexiletine (10‐4M).ConclusionsThese results suggest that lidocaine impairs but mexiletine augments vasodilation mediated by ATP‐sensitive K+channels in smooth muscle cells.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundCost reduction has become an important fiscal aim of many hospitals and anesthetic departments, despite its inherent limitations. Volatile anesthetic agents are some of the few drugs that are amenable to such treatment because fresh gas flow rate (FGFR) can be independent of patient volatile anesthetic agent requirement.MethodsFGFR and drug use were recorded at the temporal midpoint of 2,031 general anesthetics during a 2‐month preintervention period. Staff and residents were provided with their preintervention individual mean FGFR, their peer group mean, and educational material regarding volatile agent costs and low‐flow anesthesia. FGFR and drug use were remeasured over a 2‐month period (postintervention) immediately after this information (N = 2,242) and again 5 months later (delayed follow‐up), for a further 2‐month period (N = 2,056).ResultsFor all cases, FGFR decreased from 2.4 +/− 1.1 to 1.8 +/− 1.0 l/min (26% reduction) after the intervention and increased to 1.9 +/− 1.1 l/min (5% increase of preintervention FGFR) at the time of delayed follow‐up. Use of more expensive volatile agents (desflurane and sevoflurane) increased during the study period (P < 0.01). In a subgroup of 44 staff members with more than five cases in all study periods, 42 members decreased their mean FGFR after intervention. At delayed follow‐up, 30 members had increased their FGFR above postintervention FGFR but below their initial FGFR. After accounting for other predictors of FGFR, the effectiveness of the intervention was significantly reduced at follow‐up (28% reduction), but retained a significant effect compared to preintervention FGFR (19% reduction).ConclusionsAlthough individual feedback and education regarding volatile agent use was effective at reducing FGFR, effectiveness was reduced without continued feedback. Use of more expensive volatile agents was not reduced by education regarding drug cost, and actually increased.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundOperational inefficiencies in the use of operating rooms (ORs) are hidden by traditional measures of OR utilization. To better detect these inefficiencies, the authors defined two new terms, underutilization and overutilization, and illustrated how these measures might be used to evaluate the use of surgical subspecialty ORs. The authors also described capacity planning (optimizing surgical subspecialty block time allotments) using a minimal cost analysis (MCA) model.MethodsThe authors evaluated post hoc all surgeries performed over 6 yr at a large teaching hospital. To prepare utilization estimates, surgical records were categorized relative to budgeted OR block time for each subspecialty. Surgical cases beginning and ending during budgeted OR block time were categorized as budgeted utilization, budgeted time not used for surgery was underutilization, and cases beginning before/after budgeted block time were classified as overutilization. Cases that overlapped budgeted and nonbudgeted OR block time were parsed and the portions were assigned appropriately.Probability distributions were fitted to the historical patterns of surgical demand, and MCA block time budgets were estimated that minimized the costs of underutilization and overutilization for each subspecialty.To illustrate the potential savings if these MCA budgets were implemented, the authors compared actual operational costs to the estimated MCA budget costs and expressed the savings as a percentage of actual costs.ResultsThe authors analyzed data from 58,251 surgical cases and 10 surgical subspecialty blocks. Classic utilization for each block‐day by surgical subspecialty ranged from 44‐113%. Average daily block‐specific underutilization ranged from 16 to 60%, whereas overutilization ranged from 4 to 49%.ConclusionsUnderutilization and overutilization are important measures because they may be used to evaluate the quality of OR schedules and the efficiency of OR utilization. Overutilization and underutilization also allow capacity planning using an MCA model. This study indicated that the potential savings, if the MCA budgets were to be implemented, would be significant.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID