Fischer 344 rats (250-300 g) were exposed to the resulting aerosols from the pyrolysis of Spectrex Fire Extinguishant (SFE) Formulation A, a pyrotechnically generated aerosol fire suppressant, at a loading equivalent of 50 or 80 g m(-3) air for 15 or 60 min. Exposures were conducted in a 700-1 whole-body inhalation chamber under static conditions. The chamber atmosphere was analyzed for mass aerosol concentration and size distribution. Clinical observations were taken throughout the exposure. Animals were euthanized at 1 h, 6 h, 24 h, 7 days or 14 days post-exposure and underwent histopathological examination, enzyme analyses and wet/dry lung weight determination. No deaths occurred during the study. Animals exhibited signs of dyspnea, coughing, lack of coordination and lethargy during each exposure. These signs became more pronounced as the load and exposure length increased. No lesions were noted in the trachea, lung, heart or abdominal organs upon gross examination. A reversible pulmonary edema and olfactory necrosis were observed only in those animals exposed to an SFE loading equivalent to 80 g m(-3) for 60 min. Protein concentrations increased in the bronchoalveolar lavage but no changes in enzyme levels were observed. There was no significant difference between the control groups and the exposure groups for wet/dry lung weight determination.

Aerosols↗

PubMedDate not supplied

Detection of nitroaromatic compounds on coal combustion particles.

Mutagenic and nonmutagenic extracts of fly ash from fluidized bed combustion were analyzed to determine the compounds responsible for the direct mutagenic activity (mutagenic activity that does not require added metabolic enzymes in the Salmonella mutagenicity assay). Some nitro derivatives of polycyclic aromatic hydrocarbons which are direct acting mutagens were detected by tandem triple quadrupole mass spectrometry. Treatment of a mutagenic and a nonmutagenic extract with excess N2O4 resulted in 28- and 3200-fold increases, respectively, in direct mutagenicity in Salmonella typhimurium strain TA98 and an increase in the relative abundance of nitroaromatic compounds. Polycyclic aromatic compounds were also detected and tentatively identified by gas chromatography-mass spectrometry. Since, previous studies have shown that polycyclic aromatic hydrocarbons may react with NO2 to form direct-acting mutagens, it appears that the direct-acting mutagens in these fly ash extracts may be products of reactions of polycyclic aromatic hydrocarbons with NOX in the combustion gases.

Coal↗

PubMedDate not supplied

The acquisition of communicative intentions in infants eight to fifteen months of age.

Explore the source record for details and available documents.

Child Language↗

PubMedDate not supplied

Effect of local anesthetic concentration on capillary blood flow in human skin.

OBJECTIVES: The objective of this study was to evaluate and compare the effect of lidocaine, mepivacaine, and bupivacaine on capillary blood flow in humans over therapeutic and subtherapeutic concentrations. METHODS: The effect of each treatment in eight unmedicated male volunteers was measured in a randomized, controlled, double-blind comparison. Each participant received subcutaneous injections (total, 14), at separate sites on the abdomen, consisting of 0.2 ml lidocaine (0.05%, 0.5%, 1%, and 2%), mepivacaine (0.05%, 0.5%, 1%, and 2%), bupivacaine (0.025%, 0.25%, 0.5%, and 0.75%), saline, or saline with epinephrine (5 micrograms/ml), and at an additional site a needle stick was performed and no injection made. Cutaneous blood flow was measured with a laser Doppler capillary perfusion monitor before and for 60 minutes after these interventions. RESULTS: The maximum increase in cutaneous blood flow was 277 +/- 141% to 511 +/- 136% (mean +/- SE) after lidocaine, 124 +/- 110% to 316 +/- 155% after mepivacaine, and 242 +/- 193% to 725 +/- 198% after bupivacaine. The increase in blood flow depended on local anesthetic concentration: low concentrations induced minimal changes, whereas higher concentrations caused great increases in cutaneous blood flow. Injection of saline or needle stick alone increased cutaneous blood flow 285 +/- 237% and 260 +/- 121%, respectively. CONCLUSIONS: Our findings indicate that the trauma of needle stick or saline injection produces a significant increase in cutaneous capillary blood flow. Injection of clinically useful concentrations of bupivacaine and lidocaine produced even greater increases in capillary blood flow, indicating a vasodilatory effect. Injection of the lowest concentrations of lidocaine and bupivacaine caused flow to increase to a magnitude similar to that after injection of saline. In contrast, clinically useful concentrations of mepivacaine do not increase capillary blood flow to a greater extent than saline, and lower concentrations tend to blunt the increase in blood flow, indicating a mild vasoconstrictor effect.

Adult↗

PubMedDate not supplied

Comparison between ropivacaine and bupivacaine after subcutaneous injection in pigs: cutaneous blood flow and surgical bleeding.

In this randomized, blinded study, we sought to determine whether the vasoconstriction produced by ropivacaine after subcutaneous injection is sufficient to decrease surgical bleeding. Anesthesia was induced in seven piglets (weight, 12.2-20.4 kg) with intraperitoneal thiopental and maintained with intravenous methohexital. Five sites were injected with 10 ml of one of the following solutions: 0.25% ropivacaine, 0.25% bupivacaine, either solution plus 5 micrograms/ml epinephrine, or saline. Another site was left uninjected for control. Capillary blood flow was measured at each site with a laser Doppler before and ten minutes after the injections. An incision 5 cm in length was then made through the dermis, and blood loss was measured over ten minutes. We found no significant differences in capillary blood flow and blood loss between bupivacaine and ropivacaine. Addition of epinephrine decreased capillary blood flow (p less than 0.05) and tended to decrease blood loss. Capillary blood flow correlated with blood loss (r2 = 0.106; p less than 0.05). We conclude that, in contrast to previous studies, ropivacaine did not decrease capillary blood flow in our model. Similarly, ropivacaine did not reduce bleeding from surgical incisions. The reason for these surprising results is not clear but is unlikely to be the larger volume of solutions injected because no such effect was observed with saline alone.

Amides↗

PubMedDate not supplied

The reliability of epidural anesthesia for repeat ESWL: a study of changes in epidural compliance.

Changes in epidural compliance were investigated before and after extracorporeal shock wave lithotripsy (ESWL) in 11 outpatients. Epidural pressures were unchanged acutely by ESWL (p greater than 0.15). In contrast to previous reports of failures of epidural anesthesia in patients having repeat ESWL treatments, a review of our population of patients having repeat ESWL indicates that epidural anesthesia is reliable and not associated with any greater failure rate than for initial ESWL treatments. The difference between our results and previous reports of high failure rates is likely due to differences in anesthetic and surgical techniques such as: (1) use of air for loss-of-resistance when locating the epidural space, (2) differences in the time interval between ESWL treatments, and (3) frequency of use of epidural catheters.

Anesthesia, Epidural↗

PubMedDate not supplied

Aging reduces the reliability of epidural epinephrine test doses.

BACKGROUND AND OBJECTIVES: The authors recently determined that intravascular injection of an epinephrine test dose reliably produced an increase in heart rate > or = 20 beats/min in young individuals. However, aging is associated with a significant reduction in beta-adrenergic responsiveness. This study was designed to determine whether aging decreases the magnitude of heart rate (HR) increase after intravascular injection of epinephrine. METHODS: Heart rate and systolic blood pressure were recorded during randomized and double-blind injections of 3 mL lidocaine plain or lidocaine with 10 or 15 micrograms epinephrine in 30 elective surgical patients between 21 and 81 years old. RESULTS: Increasing age was associated with smaller increases in HR after intravascular injection of epinephrine. The reduction in HR increase was statistically significant after 10 micrograms (P = .006, r2 = .24), but not after 15 micrograms (P = .25, r2 = .05) of epinephrine. Heart rate increases were of greater magnitude for patients younger than 40 years old (P = .01 for 10 micrograms epinephrine, and P = .03 for 15 micrograms epinephrine). One patient (of 11) over 60 did not respond to the 15 micrograms test dose with tachycardia. Aging did not alter systolic blood pressure increases after 10 or 15 micrograms epinephrine (P = .27, r2 = .04 and P = .4, r2 = .03, respectively). CONCLUSIONS: Aging is associated with a reduction in the magnitude of HR increase after intravenous injection of epinephrine. The results suggest that to detect an intravascular injection in healthy people, a test dose containing 10 micrograms epinephrine will suffice before the age of 40. However, even 15 micrograms epinephrine will not be totally reliable in older patients, owing to decreased beta-adrenergic responsiveness.

Adult↗

PubMedDate not supplied

Effects of epidural bupivacaine after thoracotomy.

BACKGROUND AND OBJECTIVES: Combinations of bupivacaine and fentanyl are popular for postoperative epidural analgesia. However, there are little data from which to select a rational dose of bupivacaine. The study examined the effects of increasing amounts of epidural bupivacaine on postoperative analgesia, epidural fentanyl consumption, and side effects after thoracotomy. METHODS: Twenty-four patients were randomized in a double-blind manner to receive intra- and postoperative epidural infusions of either saline, 0.01% bupivacaine, 0.05% bupivacaine, or 0.1% bupivacaine at 10 mL/h. All patients received a standardized combined epidural (120 mg lidocaine and 1.5 micrograms/kg of fentanyl) and general anesthesia. Further postoperative analgesia was provided with fentanyl patient-controlled epidural analgesia (PCEA) only. RESULTS: There were no differences between groups in visual analog scale (VAS) pain scores at rest or cough, but 10 and 5 mg/h of bupivacaine provided better analgesia during physiotherapy (P < .05). The use of 10 and 5 mg/h of bupivacaine led to significant opioid sparing (50% decrease) when compared to saline and 1 mg/h bupivacaine (P < .03). There was a trend toward a greater incidence of orthostasis with the use of bupivacaine at 10 mg/h (P = .09). Incidences of opioid side effects were not different between groups. CONCLUSIONS: The results demonstrate improved analgesia with physiotherapy and significant opioid sparing when 10 and 5 mg/h doses of bupivacaine are used. However, the incidence of orthostasis may be increased with the use of 10 mg/h. Thus, 5 mg/h of epidural bupivacaine (.05% at 10 mL/h) improved analgesia, decreased opioid requirements, and did not have detectable hemodynamic effects.

Aged↗

PubMedDate not supplied

Prolonged PR interval is a risk factor for bradycardia during spinal anesthesia.

BACKGROUND AND OBJECTIVES: Bradycardia occurs during 9%-13% of spinal anesthetics and may lead to cardiac arrest. Several risk factors for the development of bradycardia have been identified, but the risk conferred by presence of abnormalities detected on preoperative electrocardiogram (ECG) has not been examined. The authors undertook the study to correlate abnormal ECG findings with the incidence of bradycardia. METHODS: The data-base was previously collected from 952 patients undergoing spinal anesthesia. Patient records were reviewed and 537 had ECGs performed within 6 months of surgery. Intraoperative bradycardia was defined as a heart rate < 50 bpm (plus > 10% decrease from baseline). Abnormalities recorded from the ECG were prolonged PR interval (PR > 0.2 sec), atrial-ventricular conduction abnormalities, evidence of chamber hypertrophy, ischemia, and infarction. The findings were compared with incidence of bradycardia using contingency tables. Significant correlations were then evaluated with logistic regression. Significance was defined as P < .05. RESULTS: The incidence of bradycardia in this population was 12%. Patients with a prolonged PR interval had an increased incidence of bradycardia (25%, P = .01). Other ECG abnormalities did not correlate with increased incidence of bradycardia. Duration of PR interval did correlate significantly (P = .001) but poorly (r2 = 0.014) with baseline heart rate. However, logistic regression demonstrated that prolonged PR interval was a significant and independent predictor for bradycardia (odds ratio = 3.2, P = .01). CONCLUSIONS: Risk factors previously identified for the development of bradycardia during spinal anesthesia include: baseline heart rate < 60 bpm, ASA physical status 1 versus 3 or 4, use of beta-blocking drugs, sensory block height > or = T5, and age < 50. The results demonstrate that prolonged PR interval on the preoperative ECG is another significant and independent predictor for bradycardia.

Adult↗