Comparison of the C-MAC videolaryngoscope with the Macintosh, Glidescope, and Airtraq laryngoscopes in easy and difficult laryngoscopy scenarios in manikins.

The C-MAC comprises a Macintosh blade connected to a video unit. The familiarity of the Macintosh blade, and the ability to use the C-MAC as a direct or indirect laryngoscope, may be advantageous. We wished to compare the C-MAC with Macintosh, Glidescope and Airtraq laryngoscopes in easy and simulated difficult laryngoscopy. Thirty-one experienced anaesthetists performed tracheal intubation in an easy and difficult laryngoscopy scenario. The duration of intubation attempts, success rates, number of intubation attempts and of optimisation manoeuvres, the severity of dental compression, and difficulty of device use were recorded. In easy laryngoscopy, the duration of tracheal intubation attempts were similar with the C-MAC, Macintosh and Airtraq laryngoscopes; the Glidescope performed less well. The C-MAC and Airtraq provided the best glottic views, but the C-MAC was rated as the easiest device to use. In difficult laryngo-scopy the C-MAC demonstrated the shortest tracheal intubation times. The Airtraq provided the best glottic view, with the Macintosh providing the worst view. The C-MAC was the easiest device to use.

Recovery of older patients undergoing ambulatory anaesthesia with isoflurane or sevoflurane.

BACKGROUND: Delayed recovery of cognitive function is a well-recognized phenomenon in older patients. The potential for the volatile anaesthetic used to contribute to alterations in postoperative cognitive function in older patients following minor surgical procedures has not been determined. We compared emergence from isoflurane and sevoflurane anaesthesia in older surgical patients undergoing urological procedures of short duration. METHODS: Seventy-one patients, 60 yr of age or older, undergoing anaesthesia expected to last less than 60 min for ambulatory surgery, were randomly assigned to receive isoflurane or sevoflurane. A standardized anaesthetic protocol was used, with intravenous fentanyl 1 microg kg(-1) and propofol 1.5-2.0 mg kg(-1) administered to induce anaesthesia. Anaesthesia was maintained with either sevoflurane or isoflurane in 65% nitrous oxide and oxygen. Early and intermediate recovery times were recorded. The Mini Mental State Examination and digit repetition forwards and backwards were administered at baseline, and at 1, 3 and 6 h postoperatively, to assess cognitive function. RESULTS: There were no between-group differences in (sevoflurane vs. isoflurane, mean +/- standard error of the mean) times to removal of the laryngeal mask airway (7.7 +/- 0.6 vs. 7.1 +/- 0.4 min), verbal response time (10.1 +/- 0.7 vs. 9.9 +/- 0.7 min) and orientation (12.1 +/- 0.7 vs. 12.1 +/- 0.7 min). Intermediate recovery, as measured by time to readiness for discharge from the post anaesthesia care unit (44.9 +/- 1.5 vs. 44.3 +/- 1.5 min), was similar in the two groups. Postoperative indices of cognitive function and attention were comparably reduced at 1 h, but returned to baseline in both groups at 6 h. CONCLUSIONS: Isoflurane and sevoflurane anaesthesia resulted in similar clinical and neurocognitive recovery profiles in older patients undergoing ambulatory surgical procedures of short duration.

Unmet need for recommended preventive health services among clients of California syringe exchange programs: implications for quality improvement.

BACKGROUND: Comprehensive preventive services are recommended for injection drug users (IDU), including screening tests, vaccinations, risk reduction counseling, and sterile syringes. Syringe exchange programs (SEP) may facilitate receipt of preventive services by IDUs, but whether SEP clients receive recommended preventive care is not known. We examined use of recommended preventive services by clients of 23 SEPs throughout California. METHODS: Five hundred and sixty SEP clients were recruited from 23 SEPs throughout California between March and September 2003. Receipt of 10 recommended preventive services and source of care (SEP versus non-SEP providers) was ascertained from client interviews. RESULTS: On average, SEP clients received only 13% of recommended preventive services and 49% of clients received none of the recommended services. Of services that were received, 76% were received from SEPs. In multivariate analysis, use of drug treatment and more frequent SEP visits were associated with receipt of recommended preventive services by clients. CONCLUSIONS: SEPs are often the only source of preventive care for their IDU clients. Still, SEP clients fail to receive most recommended preventive services. Interventions to increase use of preventive services and improve the quality of preventive care received by IDUs, such as increased access to drug treatment and SEPs, are needed.

Necrotizing fasciitis associated with injection drug use.

We studied cases of necrotizing fasciitis among injection drug users (IDUs) and non-IDUs who presented at the University of California Davis Medical Center from 1984 through 1999. Of 107 patients, 59 (55%) were IDUs and 48 (45%) non-IDUs. Among IDUs, 32 (54%) recently injected at the site of infection, and 17 patients (29%) presented with an abscess. Among non-IDUs, 17 (35%) reported a recent insect bite and 9 (19%) reported a wound or abrasion at the site of infection. Overall, seventy cases (65%) had > or = 3 debridements, and 31 patients (29%) had > 5% of their total body surface area debrided. Of all patients with necrotizing fasciitis, 16 (15%) did not survive. Among the 59 IDUs, 6 (10%) did not survive, while among non-IDUs, 10 (21%) did not survive. Our results indicate the need for a high index of suspicion for necrotizing fasciitis among patients presenting with cellulitis, a recent insect bite, wound, or recent injection drug use. Preventive interventions for necrotizing fasciitis among IDUs should include street-based education and treatment for abscesses and cellulitis.

Megestrol acetate in patients with AIDS and cachexia.

OBJECTIVE: To study the effects of a megestrol acetate liquid formulation (800 mg/d) on body weight, body composition, caloric intake, and mental outlook in patients with the acquired immunodeficiency syndrome (AIDS) who had cachexia. DESIGN: Twelve-week, multicenter, randomized, double-blind, placebo-controlled trial. SETTING: Multiple clinical centers. PATIENTS: 100 patients with AIDS who had weight loss of 10% or more of ideal body weight were randomly assigned to placebo (n = 48) or megestrol acetate (n = 52). MEASUREMENTS: Caloric intake, body weight, body composition, and sense of well-being. RESULTS: Most patients receiving megestrol acetate had increased caloric intake resulting in body weight gain (mainly fat mass). From baseline to week 8, the megestrol acetate group increased their daily caloric intake by 608 calories, whereas the placebo group increased intake by 134 calories (difference, 474 calories; 95% CI, -68 to 880 calories). Body weight in the megestrol acetate group increased by 3.86 kg from baseline to week 8, although it decreased by 0.46 kg in the placebo group (difference, 4.32 kg; CI, 2.42 to 6.22 kg). At week 8 in the megestrol acetate group, patients gained 3.68 kg in fat mass and those in the placebo group lost 0.28 kg (difference, 3.96 kg; CI, 2.49 to 5.43 kg). Body water, lean mass, and patient survival were not statistically different between treatment groups. Patients treated with megestrol acetate had an increased sense of well-being when compared with patients who received placebo. CONCLUSIONS: This megestrol acetate liquid formulation is well tolerated, increases food intake, results in body weight gain, and improves the sense of well-being in cachectic patients with AIDS.

Decompression sickness in Ireland--a review.

In the last decade there has been an increase in the incidence of decompression sickness in Ireland. The modern diver, equipped with specially developed diving equipment, is exposed to abnormal physiological conditions. This has resulted in a spectrum of medical conditions, which need to be recognised, diagnosed and treated. The department of Underwater Medicine at University College Hospital, Galway, is the only referral centre in the Republic of Ireland for patients suffering from decompression sickness. Early recognition and referral for treatment dramatically improves patient outcome. A one year's review of patients referred for treatment is presented.

Tuberculous spondylitis as a complication of intravesical bacillus Calmette-Guerin therapy.

We report a case of tuberculous spondylitis following intravesical bacillus Calmette-Guerin (BCG) instillation. A 90-year-old male physician living in South Africa received an uncomplicated 6-week course of intravesical BCG (Japanese 172 strain) for high grade superficial bladder carcinoma. He experienced a sudden onset of debilitating lower back pain 16 months following this treatment. A lytic lesion involving the anterior T11 and T12 vertebral bodies was diagnosed and subsequently biopsied. An acid-fast organism was isolated after 3 weeks of incubation and was confirmed through deoxyribonucleic acid probe hybridization as a mycobacterium. High performance liquid chromatography analysis speciated the organism as Mycobacterium bovis BCG, proving that it was acquired through the intravesical therapy.

Enflurane, halothane, and isoflurane attenuate contractile responses to exogenous and endogenous norepinephrine in isolated small mesenteric veins of the rabbit.

BACKGROUND: Volatile anesthetics exert both direct and indirect (neurally mediated) effects to produce splanchnic venodilation. These effects may result in clinically relevant hemodynamic changes. The present study examined the direct effects of isoflurane, halothane, and enflurane on rabbit mesenteric venous smooth muscle. METHODS: Changes in isometric tension, in response to exogenous and endogenous norepinephrine, were measured in isolated mesenteric vein rings before and during the administration of volatile anesthetics. RESULTS: Exogenous and electrically evoked endogenous norepinephrine produced an increase in tension with super-imposed rhythmic oscillations in tension. The exogenous norepinephrine-induced increase in tension was augmented in the presence of NG-nitro-L-arginine methyl ester (L-NAME, 5 x 10(-5) M). The oscillatory activity was not altered by L-NAME. The increase in isometric tension in response to electrical stimulation was inhibited by phentolamine (5 x 10(-6) M) and tetrodotoxin (3 x 10(-6) M). Equianesthetic (1 MAC) concentrations of isoflurane, halothane, and enflurane significantly attenuated contractile responses to exogenous and endogenous norepinephrine, with isoflurane demonstrating a more depressant effect than halothane or enflurane. Volatile anesthetics also suppressed the amplitude and frequency of oscillations in the control as well as L-NAME-treated veins. The inhibitory effects of volatile anesthetics on the oscillations were comparable to the effects of ryanodine, a specific blocker of calcium channels in sarcoplasmic reticulum. CONCLUSIONS: These results suggest that: 1) vascular endothelium, via endothelium-derived relaxing factor, modulates exogenous norepinephrine responses of the venous smooth muscle; 2) the oscillatory behavior of mesenteric veins may be attributed to calcium fluxes in the venous smooth muscle cells; and 3) the norepinephrine-dependent increases in contractile and oscillatory activity are attenuated more by isoflurane than halothane or enflurane. This indicates that volatile anesthetic-mediated splanchnic venodilation is, at least in part, due to a direct action on vascular smooth muscle as well as withdrawal of sympathetic tone.

Inhibition of neutral endopeptidase augments anaphylactic constriction of guinea pig tracheal smooth muscle.

To determine whether tachykinins participate in antigen-induced constriction of tracheal smooth muscle, we examined the effects of a neutral endopeptidase inhibitor, phosphoramidon, the tachykinin antagonist (D-Pro4, D-Trp7,9,10)-substance P(4-11), and capsaicin-induced tachykinin depletion on the responses to antigen in tracheal rings from ovalbumin-sensitized guinea pigs. In these preparations, the antigen (ovalbumin, 0.1 microgram/ml) produced reproducible and durable constriction of tracheal smooth muscle. Incubation with phosphoramidon (10 min, 10 microM) prior to antigen challenge significantly augmented the magnitude of ovalbumin-induced constriction by 22% after 30 min and by 31% after 45 min. The addition of phosphoramidon at the plateau level of antigen-induced constriction produced a similar, significant increase in the magnitude of the constriction. Following incubation with tachykinin antagonist (D-Pro4,D-Trp7,9,10)-substance P(4-11) (5 microM), the contractile response of the tracheal rings to the antigen was not altered. Furthermore, the addition of phosphoramidon (10 microM) did not significantly affect this contraction. Similarly, neither tachykinin antagonist nor phosphoramidon altered the ovalbumin-induced constriction of the tracheal rings from capsaicin-treated guinea pigs. Based on these findings, we hypothesize that tachykinins or similar broncho-constricting neutral endopeptidase substrates were released from tachykinin-containing nerve endings during immediate hypersensitivity reaction in airways, manifesting a modest and delayed constrictive effect. Following alteration of endopeptidase activity, these substances could modulate the anaphylactic constriction of the airway smooth muscle.

Effects of isoflurane on K+ and Ca2+ conductance in isolated smooth muscle cells of canine cerebral arteries.

Although isoflurane is a known cerebral vasodilator, the mechanism of isoflurane-induced vasodilation is not clear. The purpose of this study was to investigate the effects of 2.6% isoflurane (1.2 mM) on macroscopic calcium and potassium channel currents in voltage-clamped canine middle cerebral artery cells. Cells were dialyzed with K(+)-glutamate solution and superfused with Tyrode's solution for measurement of potassium current (n = 20). Stepwise depolarization from a holding potential of -60 mV to beyond -30 mV elicited an outward, slowly inactivating potassium current that was reduced 50% +/- 2% and 81% +/- 3% (mean +/- SEM) in the presence of 1 mM 4-aminopyridine and 30 mM tetraethylammonium, respectively. Calcium ionophore (A23187, 10 microM) increased the potassium current by 76% +/- 3%, suggesting calcium dependency. Isoflurane reduced the amplitude of the potassium current by 35% +/- 4%. Calcium current was measured in cells dialyzed with solution containing 130 mM Cs(+)-glutamate and superfused with solution containing 10 mM BaCl2 and 135 mM tetraethylammonium to pharmacologically isolate the calcium current (n = 13). Under these conditions, progressive depolarizing steps from -60 mV elicited an inward current that was maximally activated at +20 mV and essentially eliminated by 1 microM nifedipine. This current, resembling a long-lasting (L-type) Ca2+ channel current, was reduced 40% +/- 4% by isoflurane. The results of this study suggest that isoflurane acts directly at the vascular muscle membrane to suppress transmembrane calcium and potassium currents. The decrease in calcium current would cause vasodilation; however, the concomitant decrease in potassium current may partially antagonize the depressant effect of isoflurane mediated through calcium current reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed profound respiratory depression after premedication with trimeprazine.

Delayed, profound respiratory depression occurred in a 4-year-old boy, who had been premedicated with trimeprazine 4 h after tonsillectomy. This is a rare, but potentially fatal idiosyncratic reaction.

Differential relaxant effect of high concentrations of intravenous anesthetics on endothelin-constricted proximal and distal canine coronary arteries.

This study determined the direct effect of three intravenous anesthetics on isolated canine coronary arteries constricted with the potent endogenous vasoconstrictor endothelin. Arteries were divided into groups of large (1.3-2.5 mm) and small (250-500 microns) vessels, and arterial rings were suspended in tissue baths. The rings were stretched to an optimal resting tension and then preconstricted with an EC50 concentration of endothelin that was equivalent for both groups. Incremental concentrations (5 x 10(-6) M to 1.6 x 10(-2) M) of thiopental, ketamine, and propofol were added to the baths, and the relaxant responses were recorded. Small arteries demonstrated greater vasodilation at equivalent drug concentrations than did large arteries. These results demonstrate antagonism of the vasoconstrictor endothelin by intravenous anesthetics. Distal vessels are more sensitive than proximal vessels to the relaxant effects of the intravenous anesthetics studied. Direct effects on coronary vascular tone, however, are only apparent at concentrations above those seen clinically. Despite the potential for a differential effect on proximal and distal coronary arteries, we conclude that thiopental, ketamine, and propofol do not possess a direct effect on the tone of large or small canine coronary arteries at concentrations seen in routine clinical practice.

Isoflurane produces endothelium-independent relaxation in canine middle cerebral arteries.

Although it is generally accepted that isoflurane can cause cerebral vasodilation, the sensitivity of the cerebral vessels to this anesthetic agent remains controversial. Furthermore, the mechanism by which isoflurane produces its direct effects on the cerebral vasculature remains unknown. The purpose of this study was to determine if isoflurane-induced relaxation of canine middle cerebral arteries is dose-dependent and/or endothelium-dependent. In an additional series of experiments, isoflurane-induced relaxation was studied in the presence of indomethacin to inhibit prostacyclin release, and endothelium-independent relaxation was examined with sodium nitroprusside. The response to isoflurane was examined in middle cerebral arteries prior to and following pretreatment with 300 microM NG-monomethyl-L-arginine (LnMMA), an inhibitor of endothelium-dependent vasodilation. Vascular rings (2.5 mm in length and 600-800 microns in diameter) were suspended in tissue baths and isometric tension recorded. The rings were constricted with either 0.2 microM 5-hydroxytryptamine or 5 microM prostaglandin F2 alpha and subsequently exposed to increasing concentrations of isoflurane (0.65-4.9%). In separate experiments the procedure was repeated in vessels with and without endothelium. Isoflurane produced a dose-dependent relaxation in all vessels. This relaxation was not inhibited by LnMMA and was unaffected by the absence of endothelium. The isoflurane response was independent of cyclooxygenase inhibition. These results demonstrate that isoflurane-induced relaxation of canine middle cerebral arteries: 1) is dose-dependent; 2) is not mediated by modulation of endothelium-derived relaxing factor or a release of prostacyclin; and 3) is endothelium-independent.

Endothelium-dependent vasodilation of canine coronary collateral vessels.

The objective of this study was to determine whether endothelium-mediated relaxation occurs in canine coronary collateral vessels. Responses to endothelium-dependent vasodilators in coronary collateral vessels (250-350 microns) were compared with those obtained in normal native coronary arteries of similar size. Rings of small arteries and collateral vessels were suspended in baths, and tension was recorded. All rings were constricted with prostaglandin F2 alpha (3 microM) and subsequently exposed to cumulative concentrations of acetylcholine or bradykinin. In separate experiments, the procedure was repeated in the presence of 300 microM NG-monomethyl-L-arginine (L-NMMA) to inhibit endothelium-mediated vasodilation. Endothelium-dependent relaxation was further studied in the presence of indomethacin, and endothelium-independent relaxation was examined with sodium nitroprusside. Acetylcholine and bradykinin relaxed both normal native and collateral rings. In preconstricted small arteries and collateral vessels the concentration at 50% of maximal response of acetylcholine was 85.5 +/- 19.5 and 61.0 +/- 14.0 microns, and bradykinin was 11.9 +/- 7.4 and 10.7 +/- 2.1 microns, respectively. L-NMMA attenuated the response to acetylcholine and bradykinin in both groups. The results indicate that endothelium is present and functional in canine coronary collateral vessels. Both small coronary arteries and collateral vessels are equally responsive to endothelium-dependent vasodilators and inhibition of endothelium-dependent relaxing factor.

Intradermal inoculation with Heptavax-B. Immune response and histologic evaluation of injection sites.

The high cost of hepatitis B vaccine has limited its widespread use. Low-dose, intradermal injections of vaccine represent one option for reducing the cost. In this study, 92 nonimmune medical students were given three 0.1-mL intradermal injections of Heptavax-B containing 2 micrograms of hepatitis B surface antigen (HBsAg) at 0, 1, and 6 months. By 6 months, 90% of the subjects had developed protective levels of antibody to HBsAg (greater than or equal to 10 mIU/mL). Follow-up at 1 year showed a geometric mean concentration of antibodies to HBsAg of 396 mIU/mL for the group, and 95% had levels of antibody to HBsAg greater than or equal to 10 mIU/mL. A level of antibody to HBsAg of greater than 100 mIU/mL also was observed in more than 75% of subjects. Side effects included induration of the inoculation site in 18% at 6 months, which disappeared by 12 months, and macules that persisted at 1 year in 63%. The administration of hepatitis B vaccine intradermally is an attractive, low-cost alternative in the United States, where universal vaccination of preschool children or adolescents is being contemplated, and where booster doses are being considered.

Autoradiographic localization of substance P binding sites in rat footpad skin.

The autoradiographic distribution of binding sites for 60 pM [125I]Bolton-Hunter substance P (BHSP) was investigated in slide-mounted sections of rat footpad skin. BHSP binding sites were found over dermal papillae, postcapillary venules, sweat glands and arterioles. No binding was seen over mast cells, sebaceous glands or pacinian corpuscles. Specific BHSP binding was inhibited by substance P greater than neurokinin A greater than neurokinin B, indicating binding to an NK1 (substance P-preferring) site. The NK1 binding sites over postcapillary venules and arterioles probably represent receptors mediating plasma extravasation and vasodilatation, respectively. There was no apparent change in distribution or number of BHSP binding sites after neonatal capsaicin pretreatment, indicating a probable absence of NK1 receptors on sensory terminals. No binding sites were observed for 100 pM [125I]iodohistidyl neurokinin A (INKA).

Microbial contamination of continuous drip feedings.

We evaluated the extent and effects of bacterial contamination of an open continuous enteral feeding system. Eighty-two quantitative enteral feeding cultures and clinical data were obtained during 8 days of observation on each of 33 patients. Cultures of appropriate sites were obtained on febrile patients and compared to the enteral feeding culture. Gram negative bacilli (GNB) in the enteral feeding correlated with abdominal distension in the patients (10 of 12 patients with GNB compared to 5 of 21 without GNB; p less than 0.01). Nine of the 10 patients with GNB and distension were receiving systemic antimicrobics to which the organism was resistant. Contamination of feeding with Serratia marcescens correlated with cultures for the same organism in patients' other body sites (p less than 0.01). The feeding contaminant may have been the source of sepsis in one patient who expired from septic shock. No relationship was demonstrated between contamination and liquid stools or fever. Undiluted, canned feedings were significantly less contaminated at 24 hr (15%) than those requiring mixing of powder (94%) (p less than 0.0001). The canned feedings grew primarily enteric organisms, whereas the powder feedings grew flora typically resident on the skin. Mixing or diluting feedings appears to represent an increased risk of contamination. Growth of GNB may produce adverse effects. Further investigation into methods to limit contamination and growth is warranted.