Sternal precautions are intended to prevent complications after median sternotomy, but little data exist to support the consensus recommendations. To better characterize the forces on the sternum ...that can occur during everyday events, we conducted a prospective nonrandomized study of 41 healthy volunteers that evaluated the force exerted during bench press resistance exercise and while sneezing. A balloon-tipped esophageal catheter, inserted through the subject's nose and advanced into the thoracic cavity, was used to measure the intrathoracic pressure differential during the study activities. After the 1 repetition maximum (1-RM) was assessed, the subject performed the bench press at the following intensities, first with controlled breathing and then with the Valsalva maneuver: 40% of 1-RM (low), 70% of 1-RM (moderate), and 1-RM (high). Next, various nasal irritants were used to induce a sneeze. The forces on the sternum were calculated according to a cylindrical model, and a 2-tailed paired t test was used to compare the mean force exerted during a sneeze with the mean force exerted during each of the 6 bench press exercises. No statistically significant difference was found between the mean force from a sneeze (41.0 kg) and the mean total force exerted during moderate-intensity bench press exercise with breathing (41.4 kg). In conclusion, current guidelines and recommendations limit patient activity after a median sternotomy. Because these patients can repeatedly withstand a sneeze, our study indicates that they can withstand the forces from more strenuous activities than are currently allowed.
Purpose To quantify the impact of ignoring misclassification of a response variable and measurement error in a covariate on statistical power, and to develop software for sample size and power ...analysis that accounts for these flaws in epidemiologic data. Methods A Monte Carlo simulation-based procedure is developed to illustrate the differences in design requirements and inferences between analytic methods that properly account for misclassification and measurement error to those that do not in regression models for cross-sectional and cohort data. Results We found that failure to account for these flaws in epidemiologic data can lead to a substantial reduction in statistical power, over 25% in some cases. The proposed method substantially reduced bias by up to a ten-fold margin compared to naive estimates obtained by ignoring misclassification and mismeasurement. Conclusions We recommend as routine practice that researchers account for errors in measurement of both response and covariate data when determining sample size, performing power calculations, or analyzing data from epidemiological studies.
We designed a study to measure the functional capacity requirements of firefighters to aid in the development of an occupation-specific training program in cardiac rehabilitation; 23 healthy male ...firefighters with no history of heart disease completed a fire and rescue obstacle course that simulated 7 common firefighting tasks. They wore complete personal protective equipment and portable metabolic instruments that included a data collection mask. We monitored each subject's oxygen consumption (VO2 ) and working heart rate, then calculated age-predicted maximum heart rates (220 − age) and training target heart rates (85% of age-predicted maximum heart rate). During performance of the obstacle course, the subjects' mean working heart rates and peak heart rates were higher than the calculated training target heart rates ( t22 = 5.69 working vs target, p <0.001 and t22 = 15.14 peak vs target, p <0.001). These findings, with mean results for peak VO2 (3,447 ml/min) and metabolic equivalents (11.9 METs), show that our subjects' functional capacity greatly exceeded that typically attained by patients in traditional cardiac rehabilitation programs (5 to 8 METs). In conclusion, our results indicate the need for intense, occupation-specific cardiac rehabilitation training that will help firefighters safely return to work after a cardiac event.
Abstract For surgical patients' family members, the wait during surgery can cause anxiety that can be exacerbated if staff members provide inadequate or inconsistent information about the patient's ...status. Educational interventions and other staff-intensive measures to help reduce family members' anxiety can be time consuming for staff members and impractical in a high-volume facility. To improve communication with patients' families, nurses at a heart and vascular hospital in Dallas, Texas, designed and distributed a card containing estimated procedure times, helpful telephone numbers, and other information. A survey of family members indicated that receiving the card reduced anxiety in a significant proportion of the respondents.
