Background: There is a lack of consensus in the literature regarding phrenic nerve proximity to thoracic structures at the level of the diaphragm. This study was undertaken to provide thoracic surgeons data on phrenic nerve location in order to reduce iatrogenic injury during invasive surgery. Methods: Bilateral thoracic dissection was performed on 43 embalmed human cadavers (25 males; 18 females) and data was obtained from 33 left and 40 right phrenic nerves. The site of phrenic nerve penetration into the diaphragm was identified. Calipers were used to measure the distance from each phrenic nerve to the: inferior vena cava (IVC), descending aorta, esophagus, lateral thoracic wall and anterior thoracic wall. Results: Mean thoracic diameter of male cadavers was significantly greater than that of female cadavers (P value <0.0001). There was no statistically significant difference between the distances from each phrenic nerve to visceral structures between males and females, except regarding the distance from the right phrenic nerve to the anterior thoracic wall where males exhibited significantly greater distances (P value =0.0234). Conclusions: This study provides important data on phrenic nerve proximity to intrathoracic structures in an effort to help reduce iatrogenic injury during procedures within the thoracic cavity. Although males had a significantly larger thoracic diameter than females, the only statistically significant difference showed that the right phrenic nerve is deeper in the thoracic cavity in males. As this nerve passes closer to visceral structures it may be more susceptible to damage from pathology in surrounding vessels. This may explain the increased incidence of right phrenic nerve damage due to aortic aneurysm in males reported in the literature.

Context Some racial and ethnic groups are underrepresented in the medical field because they face unique barriers to admission to medical school. One admission requirement that can present a barrier for applicants is the physician letter of recommendation (PLOR). Undergraduate students report confusion with the application process and lack of mentorship to be two of their biggest challenges to becoming a doctor. It is especially challenging to those who already have limited access to practicing physicians. Therefore, we hypothesized that in the presence of a PLOR requirement, the diversity of students who apply and matriculate into medical school will be decreased. Objectives This study aims to determine if a relationship exists between a PLOR requirement for the medical school application and the proportion of underrepresented in medicine (URM) students applying and matriculating to that school. Methods A retrospective study was conducted utilizing data published by the American Association of Colleges of Osteopathic Medicine Application Services (AACOMAS) on the race and ethnicity of applicants and matriculants to osteopathic medical schools during the years 2009–2019. In total, 35 osteopathic schools with 44 campuses were included in the study. Schools were grouped based on whether they required a PLOR. For each group of schools, descriptive statistics were performed for the following variables: number of total applicants, class size, application rate per ethnicity, matriculation rate per ethnicity, number of applicants per ethnicity, number of matriculants per ethnicity, and percentage of student body per ethnicity. The Wilcoxon rank-sum test was utilized to detect differences between the two groups. Statistical significance was assessed at the α=0.05 level. Results Schools that required a PLOR showed decreases in the number of applicants across all races and ethnicities. Black students showed the greatest difference between groups and were the only ethnicity to show significant reductions across all outcomes in the presence of a PLOR requirement. On average, schools that required a PLOR have 37.3% (185 vs. 295; p<0.0001) fewer Black applicants and 51.2% (4 vs. 8.2; p<0.0001) fewer Black matriculants. Conclusions This study strongly suggests a relationship between requiring a PLOR’s and decreasing racial and ethnic diversity in medical school matriculants, specifically the Black applicants. Based on this result, it is recommended that the requirement of a PLOR be discontinued for osteopathic medical schools.