Milrinone improves intestinal villus blood flow during endotoxemia

PURPOSE: To determine whether the compromised intestinal villus blood flow in a rat model of endotoxemia could be improved by continuous infusion of the phosphodiesterase (PDE) inhibitor milrinone. METHODS: Twenty-four anesthetized and ventilated rats were laparotomized and an ileal portion was exteriorized and opened by an antimesenteric incision. The ileal segment was fixed with the mucosal surface upward. Microcirculatory parameters were assessed by intravital videomicroscopy. The animals were randomly assigned to receive one of three treatments: infusion of Escherichia coli lipopolysaccharides without phosphodiesterase inhibitor pretreatment (=LPS group); or infusion of LPS with milrinone pretreatment (= milrinone group), or without infusion of LPS or milrinone (=control group). Macrohemodynamic parameters (MAP, HR) and microhemodynamic parameters of ileal mucosa (mean diameter of central arterioles = D(A) and mean erythrocyte velocity within the arterioles= V(E)) were measured 30 min before and at 0, 60, and 120 min after induction of endotoxemia. Mucosal villus blood flow was calculated from D(A) and V(E). RESULTS: In the milrinone group MAP decreased 60 min after induction of endotoxemia whereas it remained stable in the control and the LPS group. In both groups given endotoxin V(E) decreased after start of LPS infusion. In contrast, D(A) decreased in the LPS group, but increased in the milrinone group after 120 min of endotoxemia. Thus, the endotoxin-induced decrease of intestinal villus blood flow was diminished but not fully restored by milrinone infusion. CONCLUSION: Our results indicate that milrinone has some beneficial microcirculatory effects during endotoxemia. Although it contributed to systemic hypotension, it attenuated intestinal mucosal hypoperfusion.     

Inadequate preanesthesia equipment checks in a simulator

PURPOSE: To assess how completely anesthesiologists check their machinery and equipment before use, and to determine what influence seniority, age and type of practice may have on checking practices. METHODS: One hundred and twenty anesthesiologists were videotaped during a simulated anesthesia session. Each participant was scored by an assessor according to the number of items checked prior to the induction of anesthesia. A checklist of 20 items derived from well-publicized, international standards was used. RESULTS: Participants were grouped according to their type of practice. Overall, mean scores were low. The ideal score was 20. There were no differences among university anesthesiologists (mean score 10.1, standard deviation 4.3), community anesthesiologists (7.5 +/- 4.3) and anesthesia residents (9.0 +/- 3.8). Each of these groups scored, on average, better than medical students (3.6 +/- 3.7) (P < 0.05). Neither age (r = 0.15, P > 0.1) nor number of years in practice (r = -0.18, P > 0.1) correlated with score. CONCLUSIONS: Our study suggests that the equipment-checking practices of anesthesiologists require considerable improvement when compared with national and international standards. Possible reasons for this are discussed and some remedial suggestions are made.     

Dexmedetomidine hemodynamics in children after cardiac surgery

Background: Dexmedetomidine has opposing effects on the cardiovascular system. Action in the central nervous system produces sympatholysis and a reduction in blood pressure, while peripherally it causes vasoconstriction leading to an increase in blood pressure. The purpose of our study is to define the concentration–response profile for these hemodynamic effects in children after cardiac surgery. Methods: A simultaneous pharmacokinetic–pharmacodynamic analysis of data from 29 children given a single bolus of dexmedetomidine 1–4 mcg·kg^?1 following cardiac surgery was undertaken using mixed effects modeling. There were four dexmedetomidine concentrations available from each patient, and mean arterial blood pressure (MAP) was recorded electronically every 5 min for 5 h after drug administration. A composite Emax model was used to relate mean arterial pressure changes to plasma dexmedetomidine concentration. Results: Children had a mean age of 2.67 years (range 4 days–14 years) and a mean weight of 12.34 (range 3.4–48.4) kg. The peripheral vasopressor effect was directly related to plasma concentration with an Emax_pos of 50.3 (CV 44.50%) mmHg, EC_50pos 1.1 (48.27%) μg·l^?1 and a Hill_pos coefficient of 1.65. The delayed central sympatholytic response was described with an Emax_neg of ?12.30 (CV 37.01%) mmHg, EC_50neg 0.10 (104.40%) μg·l^?1 and a Hill_neg coefficient of 2.35. The equilibration half‐time (T_1/2keo) was 9.66 (165.23%) min. Conclusions: Dexmedetomidine administered as a single bolus dose following cardiac surgery produces a biphasic effect on MAP. A plasma dexmedetomidine concentration of above 1.0 μg·l^?1 was associated with a 20% increase in MAP in this specific cohort. A dosage regimen involving a small bolus dose (0.5 μg·kg^?1) followed by a continuous infusion should be used to avoid initial increases in MAP.     

A comparison of four sedation techniques for pediatric dental surgery

Background: We prospectively assessed the efficacy and side effects of four sedation techniques in our dental clinic: oral midazolam, intranasal (IN) midazolam, IN midazolam combined with oral transmucosal fentanyl citrate (OTFC), and IN midazolam combined with IN sufentanil. Materials & Methods: With IRB approval, a nonrandomized open label study of moderate sedation in children undergoing dental surgery was administered during a 6 ‐month period. The sedation regimen was rotated daily at the anesthesiologist’s discretion. Each sedation was monitored by a research nurse who assessed the quality of sedation and the frequency of complications. All children were monitored during the procedure and recovery for at least 20 min, before discharge based on the University of Michigan Sedation and Ohio State behavior rating scores. Results: One hundred and two children were sedated in the dental clinic during this period. The sedation was successful in 73% (range 64% to 88%) of the children. The time to onset was greatest with OTFC (37 min) and least with IN midazolam (17 min) compared with the other two groups (20 and 30 min). Recovery after OTFC was prolonged (39 min) significantly compared with the other three groups (26.5–30 min). Efficacy of sedation and frequency of complications (9% incidence of nausea and 6% of mild hemoglobin desaturation) were similar among the groups. Conclusions: All four sedation regimens were equally effective in this cohort of healthy children. The onset and recovery with OTFC was significantly delayed compared with the other regimens. The frequency of side effects was small; there were no side effects in the PO midazolam group.