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The article discusses a study which examines the attitudes and experiences of parents in dealing with school dismissals due to the 2009 influenza A (H1N1) virus in the U.S. The study involved a randomized telephone poll of 523 parents whose child care facility or school had been temporarily closed in response to the virus. Researchers found that 75 percent of the respondents claimed that the school dismissal was not a problem for their families.

Endothelial coverage of an exposed cardiovascular stent surface leads to the occurrence of restenosis and late-stent thrombosis several months after implantation. To overcome this difficulty, modification of stent surfaces with topographical or biochemical features may be performed to increase endothelial cells' (ECs) adhesion and/or migration. This work combines both strategies on cobalt-chromium (CoCr) alloy and studies the potential synergistic effect of linear patterned surfaces that are obtained by direct laser interference patterning (DLIP), coupled with the use of Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) peptides. An extensive characterization of the modified surfaces was performed by using AFM, XPS, surface charge, electrochemical analysis and fluorescent methods. The biological response was studied in terms of EC adhesion, migration and proliferation assays. CoCr surfaces were successfully patterned with a periodicity of 10 µm and two different depths, D (≈79 and 762 nm). RGD and YIGSR were immobilized on the surfaces by CPTES silanization. Early EC adhesion was increased on the peptide-functionalized surfaces, especially for YIGSR compared to RGD. High-depth patterns generated 80% of ECs' alignment within the topographical lines and enhanced EC migration. It is noteworthy that the combined use of the two strategies synergistically accelerated the ECs' migration and proliferation, proving the potential of this strategy to enhance stent endothelialization.

Background: Hispanics and Latinos (Hispanics) are estimated to represent 17.7% of the U.S. population. Published national health estimates stratified by Hispanic origin and nativity are lacking., Methods: Four national data sets were analyzed to compare Hispanics overall, non-Hispanic whites (whites), and Hispanic country/region of origin subgroups (Hispanic origin subgroups) for leading causes of death, prevalence of diseases and associated risk factors, and use of health services. Analyses were generally restricted to ages 18-64 years and were further stratified when possible by sex and nativity., Results: Hispanics were on average nearly 15 years younger than whites; they were more likely to live below the poverty line and not to have completed high school. Hispanics showed a 24% lower all-cause death rate and lower death rates for nine of the 15 leading causes of death, but higher death rates from diabetes (51% higher), chronic liver disease and cirrhosis (48%), essential hypertension and hypertensive renal disease (8%), and homicide (96%) and higher prevalence of diabetes (133%) and obesity (23%) compared with whites. In all, 41.5% of Hispanics lacked health insurance (15.1% of whites), and 15.5% of Hispanics reported delay or nonreceipt of needed medical care because of cost concerns (13.6% of whites). Among Hispanics, self-reported smoking prevalences varied by Hispanic origin and by sex. U.S.-born Hispanics had higher prevalences of obesity, hypertension, smoking, heart disease, and cancer than foreign-born Hispanics: 30% higher, 40%, 72%, 89%, and 93%, respectively., Conclusion: Hispanics had better health outcomes than whites for most analyzed health factors, despite facing worse socioeconomic barriers, but they had much higher death rates from diabetes, chronic liver disease/cirrhosis, and homicide, and a higher prevalence of obesity. There were substantial differences among Hispanics by origin, nativity, and sex., Implications for Public Health: Differences by origin, nativity, and sex are important considerations when targeting health programs to specific audiences. Increasing the proportions of Hispanics with health insurance and a medical home (patientcentered, team-based, comprehensive, coordinated health care with enhanced access) is critical. A feasible and systematic data collection strategy is needed to reflect health diversity among Hispanic origin subgroups, including by nativity.

Inhibitory effects of the higher Basidiomycetes mushrooms, including species of genus Tremella, on the growth of Helicobacter pyroli (Hp) have been described. This study aimed to test T. mesenterica (Tm) efficacy in vivo on eradication of Hp. This IRB-approved study included 52 consenting patients diagnosed with Hp infections. The patients were selected for 10-day treatments with one of the three arms of the protocol, namely, (i) Tm 2 g, (ii) Tm given with omeprazole 20 mg, or (iii) omeprazole 20 mg, clarithromycin 500 mg, and amoxicillin 1000 mg (all regimens given twice daily). The Tm submerged cultivated mycelium in the form of tablets (1 g) was supplied free of charge to patients. Three weeks after completing the therapy, breath testing was assessed for Hp eradication. The patients who took the standard triple therapy had a 70% (n = 14) eradication rate of Hp. Of the patients taking Tm, with and without omeprazole, only one had a breath test indicative of eradication of Hp, p < 0.000. Tm-treated patients had fewer adverse events and equivalent symptomatic relief. Limitations of this study include the brief duration of Tm therapy. Longer treatment might achieve better results, but was judged to be not warranted, so as to not excessively further delay accepted therapy. Ten-day Tm was not found to be effective in vivo in eradicating Hp, whether if given with or without omeprazole. Significant symptomatic relief found among Tm-treated patients suggests that further study of Tm is well justified.

Background: The most recent pneumococcal conjugate vaccine (PCV7) shortage occurred between December 2003 and September 2004. To ensure vaccination of the highest-risk children, the Centers for Disease Control and Prevention recommended that providers delay administration of the third and fourth doses of vaccine to healthy children. We used Michigan Child Immunization Registry (MCIR) data collected from September 1, 2001 to November 30, 2004 to evaluate changes in PCV7 coverage., Methods: Vaccination and demographic data from MCIR were reviewed for 420,733 children born between September 2001 and August 2004. Main outcome measures were the proportion of children who received the third dose of PCV7 by 7 months of age and the fourth dose of PCV7 by 16 months of age. Vaccine coverage for measles, mumps, and rubella vaccine (MMR) and diphtheria, tetanus, and acellular pertussis vaccine (DTaP) was used for comparison, as these vaccines were abundant during this time period and their administration schedule is the same as the third and fourth doses of PCV7, respectively. Data analysis was conducted in spring 2005., Results: Coverage for the third dose of DTaP and the first dose of MMR remained steady, while PCV7 coverage for the third dose dropped from 29% to 11%, and the fourth dose dropped from 27% to 22% in the month following the recommendations to defer doses. Coverage returned close to pre-shortage levels shortly after the recommendations to resume the normal schedule. PCV7 coverage trends were similar for children seen in the private or public sector., Conclusions: Registry data can be useful for evaluating vaccination coverage trends during a shortage. Our findings suggest that providers were compliant with recommendations to alter vaccine administration during the shortage.

In spring 1999, the authors evaluated the effectiveness of a 1997 Florida law requiring helmet use by all bicyclists younger than age 16 years. Sixty-four counties in Florida had enacted the bicycle helmet-use law, while the other three counties had opted out. Using a cross-sectional study design, the authors conducted unobtrusive observations at bicycle racks at public elementary schools statewide. Florida children riding bicycles in counties where the state helmet-use law was in place were twice as likely to wear helmets as children in counties without the law. In counties where the state law was in place, 16,907 (79%) of 21,313 riders observed wore a helmet, compared with only 148 (33%) of 450 riders in counties where no such law was in place (crude prevalence ratio = 2.4, 95% confidence interval: 2.1, 2.8). Helmet use by children of all racial groups exceeded 60% under the law. No significant difference in use by gender was found. These data support the positive influence of a law on bicycle helmet use among children. The data reinforce the Healthy People 2010 objective that all 50 states adopt such a law for children in order to increase helmet use and consequently reduce brain injury.

Lawn mower-related injuries to children are relatively common and can result in severe injury or death. Many amputations during childhood are caused by power mowers. Pediatricians have an important role as advocates and educators to promote the prevention of these injuries.

Bicycling is a popular recreational activity and a principal mode of transportation for children in the United States, yet about 300 children die and 430,000 are injured annually. Wearing a bicycle helmet is an important countermeasure, since it reduces the risk of serious brain injury by up to 85%. The Centers for Disease Control and Prevention (CDC) have funded state health departments to conduct bicycle helmet programs, and their effectiveness has been evaluated by monitoring community bicycle helmet use. Although it would appear that measuring bicycle helmet use is easy, it is actually neither simple nor straightforward. The authors describe what they have learned about assessing helmet use and what methods have been most useful. They also detail several key practical decisions that define the current CDC position regarding helmet use assessment. Although important enough in their own right, the lessons learned in the CDC's bicycle helmet evaluation may serve as a model for evaluating other injury prevention and public health programs.

Background: Bicycle-related head injuries cause >150 deaths and 45 000 nonfatal injuries among children in the United States annually. Although bicycle helmets are highly effective against head injury, only 24% of US children regularly wear one. Georgia mandated bicycle helmet use for children, effective July 1993. During that summer, 1 rural Georgia community passed an ordinance instructing police officers to impound the bicycle of any unhelmeted child. We evaluated the effect of active police enforcement of this ordinance, combined with a helmet giveaway and education program., Methods: During April 1997, approximately 580 children in kindergarten through grade 7 received free helmets, fitting instructions, and safety education. Police then began impounding bicycles of unhelmeted children. We conducted an observational study, unobtrusively observing helmet use just before helmet distribution, several times during the next 5 months, and once 2 years later., Results: Before the program began, none of 97 observed riders wore a helmet. During the next 5 months, helmet use among 358 observed children averaged 45% (range: 30%-71%), a significant increase in all race and gender groups. In contrast, adult use did not change significantly. Police impounded 167 bicycles during the study, an average of 1 per day. Two years after program initiation, 21 of 39 child riders (54%) were observed wearing a helmet., Conclusions: Without enforcement, the state and local laws did not prompt helmet use in this community, yet active police enforcement, coupled with helmet giveaways and education, was effective and lasting.

Laws and regulations are among the most effective mechanisms for getting large segments of the population to adopt safety behaviors. These have been applied at both the state and federal levels for diverse injury issues. Certain legal actions are taken to prevent the occurrence of an otherwise injury-producing event, while other legal actions are designed to prevent injury once an event has occurred. At the federal level, effective laws and regulations have been directed at dangers posed by unsafe manufactured products or motor vehicle design. At the state level, effective safety laws and regulations have been directed at encouraging safety behaviors and regulating the use of motor vehicles or other forms of transportation. In this article, six legislative efforts are described to point out pros and cons of the legislative approach to promoting safety. Three such efforts are aimed at preventing injury-producing events from occurring: mandating child-resistant packaging for prescription drugs and other hazardous substances, regulating tap water temperature by presetting a safe hot-water heater temperature at the factory, and graduated licensing. Three other examples illustrate the value and complexities of laws designed to prevent injuries once an injury-producing event does occur: mandatory bicycle helmet use, sleep-wear standards, and child safety seat use. This article concludes with specific recommendations, which include assessing the value of laws and regulations, preventing the rescission of laws and regulations known to work, refining existing laws to eliminate gaps in coverage, developing regulations to adapt to changing technology, exploring new legal means to encourage safe behavior, and increasing funding for basic and applied research and community programs. Further reductions in childhood injury rates will require that leaders working in the field of injury prevention together provide the creativity to devise new safety devices and programs, incentives to persuade the public to adopt a "culture of safety" as a social norm, training and education to develop new leaders and workers, and the political will to challenge the status quo and engage the public interest.

All hospitals should set policies that require the discharge of every newborn in a car safety seat that is appropriate for the infant's maturity and medical condition. Discharge policies for newborns should include a parent education component, regular review of educational materials, and periodic in-service education for responsible staff. Appropriate child restraint systems should become a benefit of coverage by Medicaid, managed care organizations, and other third-party insurers.

Children with special health care needs should have access to proper resources for safe transportation. This statement reviews important considerations for transporting children with special health care needs and provides current guidelines for the protection of children with specific health care needs, including those with a tracheostomy, a spica cast, challenging behaviors, or muscle tone abnormalities as well as those transported in wheelchairs.

Objective: To determine the effect of a bicycle helmet giveaway program on helmet use among children., Methods: In 1995, a bicycle helmet giveaway program was conducted in two rural towns in Texas. Helmets were given to all 403 school children in kindergarten through grade 8. Helmet education, a bicycle rodeo, and incentives to increase helmet use were part of the program. Observations of helmet use were made before the helmet program began and after the program at several intervals throughout the school year and during the summer. A self-reported survey questionnaire was administered to children in grades 4 through 8 before the helmet program began and at several intervals during the school year to determine their attitudes about helmet use, safety perceptions, and peer pressure. A questionnaire also was administered to the parents of these children to determine attitudes and bicycle helmet use among parents., Results: Helmet use increased from 3% before the giveaway to 38% at the end of the school year, 7 months later. However, during the subsequent summer, helmet use decreased to 5%. Helmet use among 7th- and 8th-grade students was 0% at all observations periods after the giveaway. Even though 96% of all students thought that helmet use increased riding safety and 68% thought helmets should be worn at all times when riding, only 25% thought that their friends would approve of helmet use. Most parents also believed that helmets increased riding safety and should be worn, but only 23% reported always wearing one when riding a bicycle., Conclusions: Bicycle helmet giveaway programs can increase helmet use temporarily, but they may not be sufficient to sustain it. This program was not effective among 7th- and 8th-grade students.

Australia, the United States, and other developed countries, offer elementary school programs that heighten childrens' awareness about the possibility of abduction. To examine the effectiveness of such programs, an investigation was conducted of the proportion of elementary school children previously taught about "stranger" abduction and who detected they were being followed. Fifteen children were observed on four separate occasions during a seven-month period. Only 3% of the observations were detected by children. Several reasons are proposed for the poor detection rate, and recommendations for elementary school programs are made.

Background: Of the estimated 22.5 million people participating in in-line skating in the United States in 1995, about 100,000 were sufficiently injured so as to require emergency department care. We investigated the effectiveness of wrist guards, elbow pads, knee pads, and helmets in preventing skating injuries., Methods: We used data from the 91 hospital emergency departments participating in the National Electronic Injury Surveillance System, a national probability sample of randomly selected hospitals with 24-hour emergency departments. Injured in-line skaters who sought medical attention between December 1992 and July 1993 were interviewed by telephone. We conducted a case-control study of skaters who injured their wrists, elbows, knees, or heads as compared with skaters with injuries to other parts of their bodies., Results: Of 206 eligible injured subjects, 161 (78 percent) were interviewed. Wrist injuries were the most common (32 percent); 25 percent of all injuries were wrist fractures. Seven percent of injured skaters wore all the types of safety gear; 46 percent wore none. Forty-five percent wore knee pads, 33 percent wrist guards, 28 percent elbow pads, and 20 percent helmets. The odds ratio for wrist injury, adjusted for age and sex, for those who did not wear wrist guards, as compared with those who did, was 10.4 (95 percent confidence interval, 2.9 to 36.9). The odds ratio for elbow injury, adjusted for the number of lessons skaters had had and whether or not they performed trick skating, was 9.5 (95 percent confidence interval, 2.6 to 34.4) for those who did not wear elbow pads. Non-use of knee pads was associated with a nonsignificant increase in the risk of knee injury (crude odds ratio, 2.2; 95 percent confidence interval, 0.7 to 7.2). The effectiveness of helmets could not be assessed., Conclusions: Wrist guards and elbow pads are effective in protecting in-line skaters against injuries.

Objective: To evaluate the effect of a state law on reported bicycle helmet ownership and use., Design: Multistage cluster random-digit-dialing telephone survey., Setting: Georgia, June through November 1993., Participants: Adults who reported the behavior of bicyclists 4 through 15 years old., Intervention: State law mandating helmet use after July 1, 1993, for all bicyclists aged younger than 16 years., Main Outcome Measures: Bicycle helmet ownership and use., Results: Reported helmet ownership increased from 39% before the law took effect to 57% afterward (+ 46%, P = .06). Reported use increased from 33% before to 52% afterward (+ 58%, P < .05). About 7% of riders changed from "never-wearing" to "always-wearing" behavior. After the law took effect, in those households in which the law was known, 69% of riders owned and 64% used a helmet. By comparison, in those households in which the law was not known, only 30% owned and 25% used a helmet (P < .01). Reported ownership and use were 93% concordant, inversely related to rider age, and directly related to household income. Multivariable analysis indicated that race was an effect modifier of reported helmet ownership and use. In black riders, knowledge of the law appeared to be highly associated with both reported helmet ownership and use but was not significant in white riders. In white riders, though age and income were significantly associated with reported helmet ownership and use., Conclusions: This law appeared important in increasing reported helmet ownership and use, particularly in black riders. Since knowledge of the law was associated with increased ownership and use, additional publicity about the law might further increase helmet use. Because most riders who owned helmets used them, give-away programs targeting areas of low ownership may also increase use.

Objective: This article examines the relevance of self-efficacy--a cognitive process indicating people's confidence in their ability to effect a given behavior--to training and performance of pediatric resuscitation. The case is made that self-efficacy is likely to influence the development of and real-time access to cognitive, affective, psychomotor, and social aspects of resuscitation proficiency., Methods: Comprehensive literature reviews were conducted on relevant topic areas, including self-efficacy theory and empirical investigations of self-efficacy in clinical practice. Three case studies are used to illustrate the influence of self-efficacy on resuscitation practice., Results: The limited empirical evidence on the role of self-efficacy in clinical practice is consistent with self-efficacy theory: clinicians are less likely to initiate and sustain behaviors for which they lack confidence. This performance-based confidence can be distinguished from both knowledge and skills necessary to perform the behavior., Conclusions: Even clinicians who are knowledgeable and skilled in resuscitation techniques may fail to apply them successfully unless they have an adequately strong belief in their capability. General guidelines for promoting self-efficacy are presented, and specific recommendations are made for enhancing resuscitation self-efficacy during resuscitation training and postresuscitation procedures.

In 1993 there was an estimated 12.6 million in-line skaters in the US. In-line skating is popular because of its affordability and its exercise and recreational value. The main risk factors for injury include speed, obstacles and hard surfaces. Using the National Electronic Injury Surveillance System in US hospitals, 31,000 skaters were reported injured over a 12 month period. Fractures, dislocations, sprains, strains and avulsion made up 67% of all injuries. It is recommended that skaters wear protection equipment including, helmet, wrist guards, knee-pads and elbow-pads. Although head injuries from skating appear low in numbers, helmet protection is also recommended. Further studies are required that assess risk factors for injury and environmental and behavioural aspects.

In order to better understand the mechanism of hypotension and bradycardia in newborn infants under halothane anesthesia, we studied the changes in the four determinants of cardiac output in newborn piglets given 0.5 and 1% end tidal halothane. Cardiac index (CI) was measured by thermodilution. Preload was estimated from the left ventricular diastolic dimension determined by echocardiography and from the left ventricular end-diastolic pressure. Total peripheral resistance index was calculated to assess afterload. Contractility was estimated from left ventricular peak dP/dT, and from left ventricular shortening fraction and mean rate of circumferential fiber shortening determined by echocardiography. All indices of contractility decreased to approximately 50% of baseline values during administration of 1% halothane, whereas heart rate (HR) was reduced to 74% of baseline. Preload and afterload did not change significantly. Mean arterial pressure (MAP) and CI decreased to 67% and 74% of control values, respectively. Smaller, proportional reductions in all variables occurred when 0.5% halothane was administered. Control values of MAP were the only measurements significantly related to piglet age. When five additional animals underwent atrial pacing at the control HR during 1% halothane anesthesia, MAP and CI decreased to 66 and 71% of control values, respectively. dP/dT/DP40, a dP/dT point measurement independent of preload and afterload changes, decreased to 49% of control during pacing. Therefore, the major effect of halothane in newborn piglets is its potent negative inotropic action, not peripheral vasodilation or bradycardia.

A 25-month-old boy ingested six sustained-release verapamil tablets, each containing 240 mg of drug. Charcoal and cathartic were given but were never passed per rectum. Third-degree heart block, hypotension, and hypocalcemia were only transiently responsive to calcium infusions, inotropic agents, and epicardial pacing. Cardiopulmonary arrest with electromechanical dissociation ensued. Standard cardiopulmonary bypass was used to allow sufficient time for liver detoxication. Serum levels of verapamil fell during the bypass procedure, and the patient's cardiac status improved. However, continued absorption of drug after bypass resulted in a level of 4 mg/L, unresponsive circulatory failure, and death. Early, aggressive gut decontamination and the potential value of cardiopulmonary bypass procedures in poisoning that lead to cardiac depression are emphasized.

To understand better the hemodynamic effects of fentanyl anesthesia on the developing newborn, the authors studied the changes in cardiac output and its four determinants (preload, afterload, heart rate, and contractility) and plasma fentanyl kinetics in newborn piglets following the administration of high-dose fentanyl with or without atropine premedication. Twenty-five healthy farm piglets were divided into four groups. Hemodynamic studies were conducted on five who received 50 micrograms/kg intravenous fentanyl, five controls who received only 0.01-0.03 mg/kg intravenous atropine, and nine who received both agents. Fentanyl pharmacokinetics were determined by radioimmunoassay in six additional piglets. Mean plasma fentanyl concentrations were 25.4, 12.7, and 7.9 ng/ml at 5, 15, and 30 min postbolus, respectively, with an elimination phase half-life of 35.8 min. In piglets given fentanyl alone, the maximum significant (P less than 0.05) hemodynamic changes from baseline occurred at 5 min: mean aortic pressure (MAP) +42%, cardiac output -42%, heart rate -36%, left ventricular end-diastolic pressure +81%, and total peripheral resistance index +93%. The latter four hemodynamic variables were highly correlated with the logarithm of the plasma fentanyl concentration (R2 greater than 0.96, P less than or equal to 0.05). In control animals given atropine alone, only MAP changed significantly (+12-14%) during the study. Contractile indices (echocardiographic shortening fraction and left ventricular peak dP/dT) did not change significantly in any group. Piglets given fentanyl-atropine had no significant hemodynamic change during the study other than a 7-15% increase in MAP.

A 4-year-old girl had the insidious onset of congestive heart failure without apparent cause. Evaluation by echocardiography, thallous chloride TI 201 scintigraphy, and angiography suggested the presence of either a neoplasm or restrictive cardiomyopathy with a localized mass effect on the left ventricle. Pathological specimens obtained by transvascular endomyocardial biopsy and at surgery defined the pathology to be restrictive cardiomyopathy. Analysis of myocardium by electron microscopy demonstrated a previously undescribed abnormality of the contractile elements involving the myofilaments and Z bands, with generalized secondary glycogen deposition.

Mass spectrometry is widely used to measure the end-tidal concentrations of inhalation anesthetics and other gases during surgery in order to estimate their arterial concentrations. When certain breathing circuits are used in newborns, however, fresh gas or ambient air may contaminate the expired sample, introducing a systematic error in the measurement of any end-tidal gas concentration. We estimated this error in newborn piglets using carbon dioxide as an indicator substance of expired gas. The capnograms and the difference between arterial carbon dioxide tension (PaCO2) and peak-expired carbon dioxide tension (PeCO2) were compared when either a coaxial (Bain) or circle breathing circuit was used. Gas was sampled from the proximal airway and distal trachea. No combination of circuit and sampling site produced a flat alveolar phase until the circle circuit was modified with diversion valves to reduce gas mixing. The mean PaCO2-PeCO2 gradients using the coaxial/proximal sampling, coaxial/distal sampling, and modified circle/proximal sampling circuits were 12.4, 9.2, and 8.8 mm Hg, respectively. The mean PeCO2 in each of these combinations was significantly different from the corresponding mean PaCO2 (p less than 0.05). Using the modified circle circuit with distal sampling, mean PeCO2 was not significantly different from mean PaCO2: the mean PaCO2-PeCO2 gradient was 2.2 +/- 0.2 mm Hg (SEM), range, 0 to 6 mm Hg, with 95% confidence limits less than or equal to 8 mm Hg. When a coaxial breathing circuit is used in small subjects, PaCO2 may be significantly underestimated regardless of sampling site, although the circle breathing circuit with distal tracheal sampling yields accurate results.

To better understand the mechanism of hypotension and bradycardia that may occur in newborn infants during isoflurane anesthesia, we studied the hemodynamic changes in the major determinants of cardiac output in 15 newborn piglets given 0.5, 1.0, and 1.3 minimal alveolar concentrations (MAC) of isoflurane and in nine sham-instrumented, age-matched control animals. Cardiac output did not differ from the baseline reading or the control group at any isoflurane dose. Mean aortic pressure (MAP) decreased 23-45% in a dose-related manner. Total peripheral resistance index (TPRI) decreased 29% at 0.5 MAC, but did not decline further at higher concentrations. Because the decrease in MAP was offset by a similar reduction in TPRI, cardiac output did not change. Heart rate decreased significantly at 1.3 MAC (-19%). Contractility was depressed at all concentrations: left ventricular dP/dT decreased progressively at 0.5 and 1.0 MAC, and echocardiographic shortening fraction decreased significantly at 1.0 MAC. Left ventricular end-diastolic pressure was not affected. Eight of twelve animals who had bradycardia while breathing isoflurane were atrially paced at their baseline heart rate. Because pacing did not restore MAP, TPRI, and LV dP/dT/DP40 (a contractile index independent of preload and afterload) to control values, bradycardia was not primarily responsible for depression of these variables. At equipotent concentrations, isoflurane reduced MAP and TPRI more than, and cardiac output less than, halothane did in previous studies in this laboratory. Heart rate and dP/dT were decreased to a similar extent by both agents. Blood, heart, and brainstem isoflurane LD:MAC ratios were 2.04, 2.00, and 2.84, respectively, indicating a relatively low margin of safety for isoflurane in young piglets.