D. Benhamou

Phenylephrine Added to Prophylactic Ephedrine Infusion during Spinal Anesthesia for Elective Cesarean Section

BackgroundBecause ephedrine infusion (2 mg/min) does not adequately prevent spinal hypotension during cesarean delivery, the authors investigated whether adding phenylephrine would improve its efficacy. MethodsThirty-nine parturients with American Society of Anesthesiologists physical status I–II who were scheduled for cesarean delivery received a crystalloid preload of 15 ml/kg. Spinal anesthesia was performed using 11 mg hyperbaric bupivacaine, 2.5 &mgr;g sufentanil, and 0.1 mg morphine. Maternal heart rate and systolic blood pressure were measured at frequent intervals. A vasopressor infusion was started immediately after spinal injection of either 2 mg/min ephedrine plus 10 &mgr;g/min phenylephrine or 2 mg/min ephedrine alone. Treatments were assigned randomly in a double-blind fashion. The infusion rate was adjusted according to systolic blood pressure using a predefined algorithm. Hypotension, defined as systolic blood pressure less than 100 mmHg and less than 80% of baseline, was treated with 6 mg ephedrine bolus doses. ResultsHypotension occurred less frequently in the ephedrine–phenylephrine group than in the ephedrine-alone group: 37%versus 75% (P = 0.02). Ephedrine (36 ±16 mg, mean ± SD) plus 178 ±81 &mgr;g phenylephrine was infused in former group, whereas 54 ±18 mg ephedrine was infused in the latter. Median supplemental ephedrine requirements and nausea scores (0–3) were less in the ephedrine–phenylephrine group (0 vs. 12 mg, P = 0.02; and 0 vs. 1.5, P = 0.01, respectively). Umbilical artery p H values were significantly higher in the ephedrine–phenylephrine group than in the group that received ephedrine alone (7.24 vs. 7.19). Apgar scores were similarly good in both groups. ConclusionPhenylephrine added to an infusion of ephedrine halved the incidence of hypotension and increased umbilical cord p H.

Comparison Between Conventional Axillary Block and a New Approach at the Midhumeral Level

We undertook this prospective, randomized study to compare the success rate, time spent performing the blocks, onset time of surgical anesthesia, presence of complete motor blockade, and lidocaine plasma concentrations between conventional axillary block and a new approach at the midhumeral level.Both techniques were performed using a peripheral nerve stimulator. Two nerves were located at the axillary crease, whereas four nerves were located at the midhumeral level. Sixty patients undergoing upper limb surgery were assigned to one of the two techniques. The sensory block was evaluated before surgery for all of the distributions of the four major nerves of the upper extremity. A subset of patients had lidocaine plasma concentrations determined. Times to perform the blocks, mean maximum plasma lidocaine concentration, and time to peak concentration were not different between groups. The success rate of the block, as well as the incidence of complete motor blockade, was greater with the midhumeral approach compared with the axillary approach. However, the onset time to complete anesthesia of the upper extremity was shorter in the axillary approach. For brachial plexus anesthesia, we conclude that the midhumeral approach provided a greater success rate than the traditional axillary approach. (Anesth Analg 1997;84:1058-62)

Resveratrol decreases hyperalgesia induced by carrageenan in the rat hind paw

The effect of resveratrol, an aryl hydrocarbon receptor (AhR) antagonist, known to inhibit inducible cyclooxygenase-2 (COX2) and its transcription were examined in a model of hyperalgesia induced by carrageenan in the rat. Pretreatment with resveratrol did not reverse swelling and edema, but reversed the hyperalgesia induced by local tissue injury provoked by carrageenan. This reversal, occurring at resveratrol concentrations as low as 2 mg/kg, lasted for at least 48 hours. The link with COX2 activity inhibition and COX2 gene transcription, as well as a potential AhR inhibitory effect, remain to be established.

Mortality related to anaesthesia in France: analysis of deaths related to airway complications*

Death certificates from the French national mortality database for the calendar year 1999 were reviewed to analyse cases in which airway complications had contributed to peri‐operative death. Respiratory deaths (and comas) found in a previous national 1978–82 French survey (1 : 7960; 95% CI 1 : 12 700 to 1 : 5400) were compared with the death rate found in the present one: 1 : 48 200 (95% CI 1 : 140 000 to 1 : 27 500). In 1999, deaths associated with failure of the breathing circuit and equipment were no longer encountered and no death was found to be related to undetected hypoxia in the recovery unit. Deaths related to difficult intubation also occurred at a lower rate than in the previous report (1 : 46 000; 95% CI 1 : 386 000 to 1 : 13 000) in 1978–82 vs 1 : 176 000 (95% CI 1 : 714 000 to 1 : 46 000) in 1999, a fourfold reduction. In most cases, there were both inadequate practice and systems failure (inappropriate communication between staff, inadequate supervision, poor organisation). This large French survey shows that deaths associated with respiratory complications during anaesthesia have been strikingly reduced during this 15‐year period.

Effects of Age on Plasma Protein Binding of Sufentanil

The plasma protein binding of sufentanil has been studied in newborns, infants (0.5 +/- 0.3 yr), children (6.8 +/- 3.0 yr), and adults (39.5 +/- 9.0 yr). Binding of sufentanil was determined in vitro by equilibrium dialysis, and radioactive tritiated sufentanil was used for the determination of drug concentrations in plasma and buffer. The free fraction of sufentanil was significantly higher in the newborn (19.5 +/- 2.7%; P less than 0.01) than in the other age groups. The free fraction was also significantly higher in infants (11.5 +/- 3.2%; P less than 0.01) than in children (8.1 +/- 1.4%) or in adults (7.8 +/- 1.5%) but did not differ significantly between children and adults. The free fraction of sufentanil was strongly correlated with the alpha 1-acid glycoprotein plasma concentration (r = -0.73; P less than 0.001) whereas it was weakly correlated with albumin plasma concentration (r = -0.35; P less than 0.05). These data suggest that the lower concentration of alpha 1-acid glycoprotein in newborns and infants probably accounts for the decrease in protein binding of sufentanil in these age groups when compared with that in older children or adults. The increased free fraction in the neonate might contribute to the enhanced effects of lipophilic opioids in the neonate.

The use of a selective axillary nerve block for outpatient hand surgery

Although no guidelines concerning discharge criteria after axillary plexus block are available, many institutions consider recovery of motor function as a critical factor.With the midhumeral approach, the four main nerves of the upper extremity can be blocked separately using a peripheral nerve stimulator. The aim of this double-blind study was to block the radial (R) and musculocutaneous (MC) nerves with lidocaine, and the median (M) and ulnar (U) nerves with bupivacaine to recover motor function of the elbow and wrist more rapidly while maintaining long-lasting postoperative analgesia at the operative site. Patients undergoing surgery for Dupuytrens contracture were randomized into two groups in a double-blind fashion: in the control group (n = 17), each of the four nerves was infiltrated with 10 mL of a mixture of 2% lidocaine and 0.5% bupivacaine, whereas in the selective group (n = 17), the R and MC nerves were blocked with 10 mL of 2% lidocaine each and the M and U nerves were blocked with 10 mL of 0.5% bupivacaine each. Recovery of motor block was significantly faster in the selective group (231 +/- 91 vs 466 +/- 154 min). However, time to first sensation of pain was not different between groups (707 +/- 274 vs 706 +/- 291 min). In conclusion, this new approach at the midhumeral level enables the anesthesiologist to selectively administer local anesthetics on different nerves. Implications: In outpatients undergoing surgery for Dupuytrens contracture, a midhumeral block was used with the musculocutaneous and radial nerves blocked by lidocaine and the median and ulnar nerves blocked with bupivacaine. Recovery of motor function and time to discharge were shorter compared with patients who received the mixture on all four nerves. (Anesth Analg 1998;86:746-8)

Enquête mortalité Sfar–Inserm : analyse secondaire des décès par inhalation de liquide gastrique

Aspiration of gastric contents is a major complication in relation with the practice of anaesthesia. The present article is aimed at describing detailed data related to aspiration which were obtained during the French national survey on anaesthesia-related mortality conducted by both Sfar and CépiDC-Inserm. Information regarding methods of the survey and the main results has been previously published. In brief, the first part of the survey described the number and characteristics of anaesthetic procedures performed in 1996 (denominator). The second survey analysed deaths related to anaesthesia which were identified from death certificates of the calendar year 1999. Because of the numerical importance of aspiration among the causes of deaths, a secondary analysis was undertaken to assess into details factors leading to the occurrence of this complication. Eighty-three cases of death were found related to aspiration, i.e. one-fifth of deaths related completely or partially to anaesthesia, implying a death rate of one for 221,368 general anaesthetic procedures or 4.5 x 10(-6) (95% IC: 0.8 x 10(-6)-14 x 10(-6)). Patients involved were all in a severe clinical condition (ASA> or =3: 92%), very old and often scheduled for urgent abdominal surgery. Two cases of death occurred during colonoscopy but none in obstetric patients. Aspiration almost always occurred during induction of anaesthesia. Analysis of practice patterns disclosed significant deviations from recommendations. French anaesthetists should voluntarily move through a personal and active process toward an improvement of their practice to reduce the incidence of aspiration.

Adverse events with medical devices in anesthesia and intensive care unit patients recorded in the French safety database in 2005-2006

Background:French regulations require that adverse events involving medical devices be reported to the national healthcare safety agency. The authors evaluated reports made in 2005–2006 for patients in anesthesiology and critical care. Methods:For each type of device, the authors recorded the severity and cause of the event and the manufacturers response where relevant. The authors compared the results with those obtained previously from the reports (n = 1,004) sent in 1998 to the same database. Results:The authors identified 4,188 events, of which 91% were minor, 7% severe, and 2% fatal. The cause was available for 1,935 events (46%). Faulty manufacturing was the main cause of minor events. Inappropriate use was the cause in a significantly larger proportion of severe events than minor events (P < 0.001) and was usually considered preventable via improved knowledge or device verification before use. Compared to with that in 1998, the annual number of reported events doubled and the rate of severe events decreased slightly (12–10%, P = 0.03). The rate of events related to manufacturing problems remained stable (59–60%, P = nonsignificant), and the rate of events caused by human errors was 32–42% (P = 0.01). There were no changes in the mortality rate (2% in both studies). Conclusions:The number of adverse events related to medical devices indicates a need for greater attention to these complex pieces of equipment that can suffer from faulty design and manufacturing and from inappropriate use. Improvements in clinician knowledge of medical devices, and to a lesser extent improvement in manufacturing practices, should improve safety.

Endothelial oxidative stress induced by serum from patients with severe trauma hemorrhage

ObjectiveShock induces oxidative stress by ischemia-reperfusion phenomenon. Endothelial cells are involved in the inflammatory response and oxidative stress responsible for microcirculation impairment and organ failure. We examined the potential of serum from patients to induce in vitro reactive oxygen species production by cultured human umbilical vein endothelial cells (HUVECs).PatientsThree groups were compared: hemorrhagic shock trauma patients, isolated brain injured patients, and healthy volunteers.MethodsIn the hemorrhagic shock group we sought a correlation between reactive oxygen species production and severity of shock. Serum was separated and perfused in an in vitro model of perfused HUVECs. Ex vivo reactive oxygen species production was assessed by fluorescence microscopy using dichlorodihydrofluorescein, an intracellular dye oxidized by H2O2. Results are expressed in proportional change from baseline and normalized by protidemia to control for variation related to hemodilution.ResultsReactive oxygen species production by endothelial cells exposed to serum from hemorrhagic shock patients (46.2±24.9%) was significantly greater than in those with brain injury (3.9±35.1%) and in healthy volunteers (−6.8±5.8%). In the hemorrhagic shock group dichlorodihydrofluorescein fluorescence was strongly correlated positively to Simplified Acute Physiology Score II and lactatemia and negatively to [HCO3−].ConclusionsSerum from trauma patients with hemorrhagic shock induces reactive oxygen species formation in naive endothelial cells which is correlated to shock severity.

Respiratory effects of epidural sufentanil after cesarean section.

The ventilatory response to CO2 was measured to evaluate the degree of respiratory depression after epidural sufentanil. After cesarean section performed with bupivacaine epidural anesthesia, 14 patients received either 30 micrograms (n = 7) or 50 micrograms (n = 7) of epidural sufentanil. Respiratory measurements were made before and 15, 45, and 120 min after sufentanil injection. The presence and severity of sedation and other nonrespiratory side effects were evaluated throughout the study. Plasma sufentanil assays were performed on blood samples obtained at frequent intervals during the first 2 h. Although changes in resting ventilation did not occur, both sufentanil doses depressed the ventilatory response to CO2. After sufentanil 30 micrograms, the slope of the CO2 response curve decreased significantly at 45 and 120 min (control value, 2.33 +/- 0.3 L.min-1.mm Hg-1 [mean +/- SEM] vs 1.61 +/- 0.24 and 1.72 +/- 0.15, respectively, P less than 0.05). After sufentanil 50 micrograms, significant decreases occurred at 15 and 45 min (control value, 2.84 +/- 0.71 vs 1.81 +/- 0.48 and 1.48 +/- 0.31 L.min-1.mm Hg-1, respectively). The mean maximal decrease in the slope occurred at 45 min and was more pronounced after 50 micrograms (-42.3% +/- 7.4%) than after 30 micrograms (-27.4% +/- 9.9%). Analgesia was similar in both groups. Side effects, particularly sedation, were more severe with the 50-micrograms dose. We conclude that 30 micrograms of epidural sufentanil is preferable to the higher dose with regard to both respiratory and nonrespiratory side effects. Even with the lower dose, monitoring of ventilation is advisable for a minimum of 2 h.