AANA Journal course: update for nurse anesthetists--a comprehensive review of remifentanil: the next generation opioid.

Over the last two decades, profound changes have taken place in the way elective surgery is practiced with the majority of surgical patients now admitted and discharged through ambulatory surgical facilities. After initial hesitation on the part of the surgeons, anesthesia care providers, and patients and their families, this practice is now clearly accepted. A variety of surgical advances (e.g., new endoscopic procedures, laser technology, and extracorporeal shock wave procedures) have allowed surgeons to simplify and abbreviate surgical procedures. Anesthesia care providers now, more than ever, need rapid acting agents to keep apace with these surgical technological advances; the pressure to produce rapid room turnover and rapid recovery from anesthesia is unprecedented. Ideally, the anesthetic care plan and drug selection should precisely match the need of the individual patient and the surgical procedure. Remifentanil, a new member of the fentanyl family, is the first ultra-short-acting opioid that can be rapidly titrated and individualized for various levels of surgical stimuli. Relatively large doses can be administered, permitting rapid extubation and awakening at the end of the procedure. Remifentanil differs from all other opioids, possessing an ester linkage that allows predictable pharmacokinetics. Remifentanil may have potential for clinical exploitation where rapid onset and offset of opioid effects are desirable.

Occurrence of autoantibodies to cilia in lambs with a 'coughing syndrome'.

A respiratory disease of lambs that has been termed the 'coughing syndrome' has been observed in the mid-western region of the United States of America. Mycoplasma ovipneumoniae (M. ovipneumoniae) and Mycoplasma arginini (M. arginini) were routinely isolated from the respiratory tract of lambs with this disease. A high level of antibodies reactive with ovine cilia of the upper respiratory tract was detected in the sera from many of the lambs in affected flocks but not in sera of lambs from unaffected flocks. The reactivity of these antibodies with cilia was demonstrated by ELISA and confirmed by indirect immunofluorescent staining and western immunoblotting. These antibodies were predominantly of the IgG isotype. They were distinct from cold or warm agglutinins and could be absorbed from the sera with cilia but not with antigens of common bacterial pathogens of the sheep respiratory tract including M. ovipneumoniae, M. arginini, Pasteurella haemolytica, Pasteurella multocida or Neisseria ovis. In addition, their occurrence appeared to be independent of the specific antibodies to M. ovipneumoniae and M. arginini. Western immunoblotting indicated that the antibodies were directed primarily against an antigen with apparent molecular weight of 50 kDa. In one flock from which serial serum samples were collected from the same lambs over a 10-month period, antibodies to ovine cilia developed before the onset of the clinical disease and persisted for a period of several months until most of the lambs had apparently recovered. However, colonization of the respiratory tract of the lambs by M. ovipneumoniae preceded the production of these antibodies. Sequential serum samples taken from another flock, with no known history of this coughing, showed no such antibodies throughout the sampling period. It is suggested that an immunopathologic mechanism involving production of autoantibodies directed against a ciliary antigen of the lambs could be a contributing factor to the pathogenesis of this clinical disease.

Demonstration of a capsule on Mycoplasma ovipneumoniae.

OBJECTIVE: To examine Mycoplasma ovipneumoniae for presence of a capsule and its potential role in adherence. SAMPLE POPULATION: 17 isolates of M ovipneumoniae and 2 isolates of M arginini, recovered from sheep with respiratory tract disease. PROCEDURE: Mycoplasmas were cultured in modified Fills broth medium, ovine fetal lung cells, or ovine tracheal ring explants. Pelleted mycoplasmas or ring cultures infected with mycoplasmas were treated with ruthenium red or polycationic ferritin and visualized by transmission electron microscopy. Reactivity of several lectins with the mycoplasmas was studied by use of a microtitration plate agglutination test. RESULTS: Electron microscopy revealed a large number of M ovipneumoniae cells covered with an electron dense-stained amorphous material suggesting that it was a capsule. Multiple passages of the microorganisms in modified Friis broth medium decreased thickness of the capsule, but not percentage of cells encapsulated. Marked differences were observed when M ovipeumoniae isolates grown in modified Friis broth medium or co-cultured with ovine fetal lung cells were compared for capsular thickness or percentage of encapsulation. In thin sections of ruthenium red-stained tracheal ring cultures, the mycoplasmas appeared to be in close contact with cilia through their capsule. All isolates of M ovipneumoniae reacted strongly with wheat germ agglutinin lectin. CONCLUSIONS: Mycoplasma ovipneumoniae produces a polysaccharide capsule with variable thickness that is dependent on culture conditions and strain. Morphologic observations suggest that this capsule facilitates adherence of the organism to ciliated epithelium.

Field isolates of Mycoplasma ovipneumoniae exhibit distinct cytopathic effects in ovine tracheal organ cultures.

Ovine tracheal ring explants were infected with four different Mycoplasma ovipneumoniae and one M. arginini field isolate and their ability to induce cytopathic effects was tested by measuring ciliary activity and intracellular calmodulin release. Infected tracheal rings showed significantly decreased ciliary activity as compared to the non-infected control rings. There were, however, marked differences between isolates in the onset and severity of the effects which correlated with their ability to produce hydrogen peroxide. Infected tracheal rings released more calmodulin than the non-infected controls. The amount of calmodulin released also varied between isolates, and somewhat reflected the degree of loss of ciliary activity in the corresponding rings induced by the different isolates. Light and electron microscopic examinations of infected tracheal rings revealed disorganisation and sloughing of the epithelium, and association of mycoplasmas only with the cilia. Following repeated in vitro passages, the organisms had reduced ability to inhibit ciliary activity which correlated with decreased hydrogen peroxide production. Addition of catalase to the organ cultures delayed loss of ciliary activity. These results suggest that M. ovipneumoniae induced ciliostasis in ovine tracheal ring explants which correlated with hydrogen peroxide production. Furthermore, these M. ovipneumoniae-induced injuries to respiratory epithelial cells could contribute to the role that this organism may play in sheep respiratory disease.

Application of multiplex polymerase chain reaction for rapid identification of Campylobacter jejuni and C coli associated with reproductive failure.

OBJECTIVE: To evaluate a multiplex polymerase chain reaction (PCR) to distinguish Campylobacter jejuni from C coli as causes of reproductive failure. PROCEDURE: Review of clinical cases of reproductive failure attributed to C jejuni or C coli. RESULTS: A case of swine abortion was attributable to infection with C coli. The porcine abortion isolates were verified as C coli by restriction fragment length polymorphism and multiplex PCR. Cases of endometritis in a fox and in mink caused by C jejuni were reviewed, and isolates were confirmed as C jejuni by results of the multiplex PCR. CONCLUSION: Multiplex PCR was useful in identifying C coli and C jejuni recovered from atypical cases of reproductive failure. Multiplex PCR in conjunction with conventional assays may be useful for verifying other unusual instances of campylobacteriosis.

Interaction of Haemophilus parasuis with nasal and tracheal mucosa following intranasal inoculation of cesarean derived colostrum deprived (CDCD) swine.

Twenty-three cesarean derived, colostrum deprived pigs were obtained at 5 wk of age and inoculated intranasally with either 1.4 x 10(8) colony forming units of Haemophilus parasuis or sterile phosphate buffered saline. Pigs were euthanized at 4, 8, 12, 18, 26, or 36 h post-inoculation and tissues from the oropharynx and respiratory tract were obtained for qualitative bacterial culture, immunohistochemistry for H. parasuis antigens, and light and transmission electron microscopy. Haemophilus parasuis was consistently isolated from the nasal cavity (17/17, 100%) and trachea (13/17, 76%) and rarely isolated from the lung (3/17, 18%) and blood stream (1/17, 6%) of infected pigs. Antigens of H. parasuis were sporadically detected on the nasal mucosa (6/17, 35%) and trachea (8/17, 47%). Light microscopic lesions included submucosal and intraepithelial infiltrates of neutrophils and infrequent, patchy loss of cilia. Ultrastructural changes in nasal mucosal epithelial cells included cell protrusion, loss of cilia, and dilation of the cytocavitary network. Bacteria were infrequently identified and were either within an amorphous material at the apical surface of the cilia or were between individual cilia. These results suggest H. parasuis associates with the nasal mucosa and can induce a suppurative rhinitis with nasal mucosal epithelial cell degeneration. This process may represent an initial event in the pathogenesis of H. parasuis infection of swine.

Sevoflurane use in Veterans Affairs medical centers: utility, safety, and cost-effectiveness.

It has long been realized that the Veterans Affairs (VA) patient has a high incidence of multiorgan system diseases, especially diseases of the pulmonary and cardiovascular systems. The typical Birmingham VA Medical Center patient presenting for surgery is male, with a national mean age of 60 years. More than one half of these patients have a significant history of current or prior tobacco abuse, and many have cardiovascular impairments. When sevoflurane became available, a careful review of the characteristics of the drug, as well as cost comparisons of inhaled agents, was done by our department of anesthesia. Sevoflurane appears to be an ideal inhaled anesthetic for the veteran patient population. If used appropriately, sevoflurane can be administered safely at a cost comparable to desflurane.

Comparison of tests for detecting leaks in the low-pressure system of anesthesia gas machines.

Small leaks in the low-pressure system (LPS) of the anesthesia gas machine can cause hypoxia or patient awareness. We sought to determine the relative sensitivities of the various tests recommended for detecting LPS leaks before anesthesia. Special adapters were fashioned to create leaks of six different sizes in the LPS that were equivalent to the following: a single 25-, 22-, 20-, or 15-gauge needle, two 15-gauge needles, or a 2.5-mm endotracheal tube connector. With each leak condition, five different leak tests were performed on three each of the following machines: Ohmeda Modulus I, Ohmeda Modulus II-Plus, and North American Dräger Narkomed (2A, 3 and 4), for a total of 54 leaks to be detected for each leak test (3 x 3 x 6). The number of leaks detected with each test was compared by Fisher's exact test, P < 0.05 being considered significant. Only the negative pressure leak test detected all 54 leaks, a significant difference from the positive pressure test, which detected the least number of leaks, 28 (P < 0.05). Some leak tests are more suitable for specific anesthesia machines. Adoption of the negative pressure test as a universal LPS leak test may prevent the risks associated with using the wrong test for the particular anesthesia machine: hypoxic gas or patient awareness.

Comparison of the antigen distribution of two US porcine reproductive and respiratory syndrome virus isolates with that of the Lelystad virus.

One hundred 4-week-old cesarean-derived colostrum-deprived pigs were inoculated with one of two different US porcine reproductive and respiratory syndrome virus (PRRSV) isolates (VR2385, VR2431) or the European Lelystad virus to detect and compare the location and amount of virus antigen. Interstitial pneumonia, myocarditis, lymphadenopathy, and encephalitis were consistently seen in all three groups; however, disease and lesions were more severe in the VR2385 group. Immunohistochemical evaluation of formalin-fixed tissues revealed virus antigen in alveolar macrophages in lungs of 22/25, 14/25, 14/25, and 0/25 of the VR2385, VR2431, Lelystad, and control pigs, respectively. Follicular macrophages and dendritic cells in the lymph nodes of 14/25, 10/25, 10/25, and 0/25 pigs from the VR2385, VR2431, Lelystad, and control groups, respectively, stained positive for virus antigen. Similar cells in the tonsils from 25/25, 21/25, 23/25, and 0/25 pigs from the VR2385, VR2431, Lelystad, and control groups, respectively, stained positive for virus antigen. Other tissues and cells in which virus antigen was detected included macrophages and endothelial cells in the heart, macrophages, and interdigitating cells in the thymus, macrophages and dendritic cells in the spleen and Peyer's patches, and macrophages in hepatic sinusoids, renal medullary interstitium, and adrenal gland. PRRSV persisted in macrophages in the lung, tonsil, lymph node, and spleen for at least 28 days. Significantly more PRRSV antigen was detected in the lung (P < 0.01), lymph nodes (P < or = 0.05), and tonsils (P < 0.05) of the VR2385 pigs than was detected in the same tissues of the VR2431 and Lelystad pigs. The cell types in which PRRSV antigen was detected and the distribution of PRRSV antigen-positive cells within particular tissues and organs were generally similar for the different virus inoculation groups despite differences in virulence of the isolates.

Comparative pathogenicity of nine US porcine reproductive and respiratory syndrome virus (PRRSV) isolates in a five-week-old cesarean-derived, colostrum-deprived pig model.

One hundred forty-six 5-week- old cesarean-derived, colostrum-deprived (CDCD) pigs were inoculated intranasally with 1 of 9 US porcine reproductive and respiratory syndrome virus (PRRSV) isolates. Differences were found in severity of clinical respiratory disease, rectal temperatures (P < or = 0.001), gross lung lesions (P < or = 0.001), and microscopic lung lesions (P < or = 0.05). Gross lung lesions were generally most severe 10 days postinoculation and were distributed primarily in the cranial, middle, and accessory lobes and ventromedial portion of the caudal lung lobes. Mean gross lung lesion scores estimating the percentage of lung affected by pneumonia at 10 days postinoculation ranged from 16.7% +/- 2.8% (mean +/- SEM, n = 10) for isolate ISU-51 to 62.4% +/- 5.7% (n = 10) for isolate ISU-28. Microscopic lung lesions were characterized by hyperplastic and hypertrophied type 2 pneumocytes, septal infiltration by mononuclear cells, and accumulation of necrotic alveolar exudate. Lymph node follicular hyperplasia and focal necrosis was seen with all 9 isolates. This CDCD pig model was useful for demonstration of significant differences in pathogenicity among US PRRSV isolates. This difference in pathogenicity may help explain the variation of severity of clinical disease observed in field outbreaks of porcine reproductive and respiratory syndrome and should provide for meaningful comparison of PRRSV genotypes.

Comparison of the pathogenicity of two US porcine reproductive and respiratory syndrome virus isolates with that of the Lelystad virus.

The Lelystad virus or one of two US isolates (VR2385, VR2431) of porcine reproductive and respiratory syndrome virus were given intranasally to 25 4-week-old cesarian-derived colostrum-deprived pigs. Pigs from these groups were necropsied at 1, 2, 3, 5, 7, 10, 15, 21, or 28 days postinoculation. The Lelystad virus and VR2431 induced mild transient pyrexia, dyspnea, and tachypnea. VR2385 induced labored and rapid abdominal respiration, pyrexia, lethargy, anorexia, and patchy dermal cyanosis. All three isolates induced multifocal tan-mottled consolidation involving 6.8% (n = 9; SEM = 3.4) of the lung for Lelystad, 9.7% (n = 9, SEM = 2.7) of the lung for VR2431, and 54.2% (n = 9, SEM = 4.4) of the lung for VR2385 at 10 days postinoculation. Characteristic microscopic lung lesions consisted of type 2 pneumocyte hypertrophy and hyperplasia, necrotic debris and increased mixed inflammatory cells in alveolar spaces, and alveolar septal infiltration with mononuclear cells. Lymphadenopathy with follicular hypertrophy, hyperplasia, and necrosis was consistently seen. Similar follicular lesions were also seen in Peyer's patches and tonsils. Lymphohistiocytic myocarditis and encephalitis were reproduced with all three isolates. Clinical respiratory disease and gross and microscopic lung lesion scores were considerably and significantly more severe in the VR2385-inoculated pigs. All three viruses were readily isolated from sera, lungs, and tonsils throughout the 28 days of the study. The lymphoid and respiratory systems have the most remarkable lesions and appear to be the major site of replication of these viruses. This work demonstrated a marked difference in pathogenicity of porcine reproductive and respiratory syndrome isolates.

Experimental reproduction of Haemophilus parasuis infection in swine: clinical, bacteriological, and morphologic findings.

Haemophilus parasuis is a common cause of polyserositis and polyarthritis in swine. Little is known about the mucosal and systemic sites of replication and lesions which follow an aerosol exposure to H. parasuis. In this experiment 5-week-old cesarean-derived, colostrum-deprived (CDCD) pigs were inoculated intranasally with an inoculum containing 2 x 10(9) colony-forming units of H. parasuis. Two principals and one control pig were necropsied at 12, 36, 84, and 108 hours postinoculation (PI) and samples obtained for bacteriologic culture and microscopic examination. Inoculated pigs developed clinical signs of inappetence, reluctance to move, lameness, and a serous nasal discharge. Macroscopic findings included a fibrinous polyserositis and polyarthritis 36 hours PI which became progressively more severe at 84 and 108 hours PI. No lung lesions were grossly visible. Microscopic lesions included a mild purulent rhinitis at each post inoculation interval and fibrinous to fibrinopurulent synovitis and serositis at 36, 84, and 108 hours PI. A focal suppurative bronchopneumonia was observed in one pig examined at 36 hours PI. The nasal cavity and trachea were the only mucosal sites from which H. parasuis was reisolated. Haemophilus parasuis was isolated from the blood and systemic sites at 36, 84, and 108 hours PI. Findings presented indicated that intranasal inoculation of 5-week-old CDCD pigs with H. parasuis results in clinical signs and lesions of polyserositis and polyarthritis typical of field cases and is a useful model for the study of H. parasuis pathogenesis. The results also suggest that H. parasuis initially colonizes the nasal mucosa.

Immunohistochemical identification of porcine reproductive and respiratory syndrome virus (PRRSV) antigen in the heart and lymphoid system of three-week-old colostrum-deprived pigs.

Porcine reproductive and respiratory syndrome virus (PRRSV) antigens were detected by a streptavidin-biotin complex technique in tissues of 3-week-old colostrum-deprived pigs that had been inoculated intranasally with PRRSV and had developed moderate respiratory disease. Moderate, multifocal, tan-colored consolidation of the lungs and severe enlargement of the lymph nodes were noted at necropsy. Severe interstitial pneumonia characterized by type 2 pneumocyte proliferation, septal infiltration with mononuclear cells, and accumulation of macrophages and necrotic cells in alveolar spaces was observed at 4 and 9 days postinoculation. Moderate multifocal perivascular lymphohistiocytic myocarditis was observed at 9 days postinoculation. Marked lymphoid follicular hyperplasia and follicular necrosis in the tonsil, spleen, and lymph nodes was observed. A monoclonal antibody that recognizes a conserved epitope of PRRSV nucleocapsid protein was used as primary antibody for immunohistochemistry. Antigen was readily detected in alveolar macrophages in the lung and in endothelial cells and macrophages in the heart. Macrophages and cells resembling dendritic cells in tonsil, lymph nodes, thymus, and spleen also stained intensely positive for viral antigen. PRRSV appears to replicate primarily within macrophages in the respiratory and lymphoid systems of the pig.

The effects of carrier gas composition on the performance of the Tec 6 desflurane vaporizer.

The new Tec 6 desflurane vaporizer is an electrically heated, pressurized, electromechanically coupled dual-circuit blender. We hypothesized that carrier gas viscosity should affect the electromechanical coupling of the fresh gas and vapor circuits, and that desflurane output should vary with different carrier gases. In the first portion of the study, the performance of eight vaporizers was evaluated using a constant dial setting of 10% desflurane with four different carrier gases and three different fresh gas flow rates. In the second portion of the study, the carrier gas flow rate was maintained at 1, 5, or 10 L/min, and vaporizer output was analyzed at all integer dial settings from 1% to 18%. Vaporizer output was highest when oxygen was the carrier gas and lowest when nitrous oxide was the carrier gas. This effect was accentuated at low fresh gas flow rates and correlated with carrier gas viscosity. At a flow rate of 1.0 L/min with a constant dial setting of 10%, the averaged output from vaporizers was 10.3 +/- 0.66, 9.4 +/- 0.58, 8.7 +/- 0.52, and 8.1 +/- 0.44 vol% for 100% oxygen, air, 30% oxygen plus 70% nitrous oxide, and 100% nitrous oxide, respectively. With 100% nitrous oxide as the carrier gas at a flow rate of 1.0 L/min, the vaporizer delivered 2 vol% less than the dial setting at dial settings in excess of 12%. Differences between the analyzed concentration and the dial setting were most pronounced with high concentrations of nitrous oxide at low fresh gas flow rates.

An indirect microimmunofluorescence test for detection of chlamydial antibodies in ovine fetal fluids.

The objective of this study was to evaluate an indirect microimmunofluorescence test (IMIF) for detection of chlamydial antibodies in serum and/or thoracic fluids of aborted ovine fetuses. One hundred eighty-two ovine fetuses, including 64 fetuses from 40 ewes that were experimentally infected with an ovine abortion strain of Chlamydia psittaci at gestation days 90-100, 10 fetuses from 6 normal ewes, and 108 fetuses selected from those received at the Iowa Veterinary Diagnostic Laboratory, were evaluated in this study. Fetuses from experimentally infected ewes were examined 4-60 days after inoculation. The IMIF findings were compared with the results of complement fixation serology for chlamydiae and concentrations of immunoglobulin (IgG). Chlamydiae-specific antibodies were detected by IMIF in 28 of 38 fetuses infected with C. psittaci. Elevated levels of IgG and IMIF titers > or = 1:8 were consistent findings in ovine fetuses infected with chlamydiae for more than 24 days. IgG levels and titers of chlamydial antibodies increased with maturity of the fetus and duration of chlamydial infection. Chlamydial antibodies were not detected with the complement fixation test. Fluids from ovine fetuses aborted as a result of other causes also were examined, and IMIF results were negative. The results of this study indicate that the IMIF is a useful and relatively rapid test for identification of chlamydial antibodies in ovine fetuses.