Evaluating gender parity in operative experience for otolaryngology residencies in the United States.

OBJECTIVES: Gender disparity exists in medicine, such as differences in pay and promotion opportunities. We hypothesize that there is also a gender difference in graduate medical education as manifested by operative case volume. This study compares surgical case volume by gender for graduating US otolaryngology residents. STUDY DESIGN: Cohort study. METHODS: With data use approval from the Accreditation Council for Graduate Medical Education, we evaluated the key indicator case log summaries of graduating otolaryngology residents from 2009-2017. Mean and standard deviation were used for all cases, and t-tests were used to compare cases by resident gender. The Bonferroni method was used to adjust for multiple comparisons across years. RESULTS: Data from 1740 male and 804 female residents were evaluated. Across all years, the average number of key indicator cases reported was 778.8 and 813.6 by female and male residents, respectively, with an average difference of 34.8 cases per graduating year (95% confidence interval [CI] 19.4, 50.2; P < .001). When a resident self-reported the role of resident surgeon/supervisor, the average number of key indicator cases reported was 602.6 and 643.9 by female and male residents, respectively, with an average difference of 41.3 cases per graduating year (95% CI, 28.0, 54.6; P < .001). CONCLUSION: Gender-based discrepancies in surgical case volume exist among graduating otolaryngology residents. This disparity is partially attributed to the self-reported role in the surgery. This study has identified those discrepancies so that training programs can implement strategies to ensure improved gender parity. LEVEL OF EVIDENCE: 2b Laryngoscope, 130:1651-1656, 2020.

A mathematical model of the use of supplemental oxygen to combat surgical site infection.

Infections are a common complication of any surgery, often requiring a recovery period in hospital. Supplemental oxygen therapy administered during and immediately after surgery is thought to enhance the immune response to bacterial contamination. However, aerobic bacteria thrive in oxygen-rich environments, and so it is unclear whether oxygen has a net positive effect on recovery. Here, we develop a mathematical model of post-surgery infection to investigate the efficacy of supplemental oxygen therapy on surgical-site infections. A 4-species, coupled, set of non-linear partial differential equations that describes the space-time dependence of neutrophils, bacteria, chemoattractant and oxygen is developed and analysed to determine its underlying properties. Through numerical solutions, we quantify the efficacy of different supplemental oxygen regimes on the treatment of surgical site infections in wounds of different initial bacterial load. A sensitivity analysis is performed to investigate the robustness of the predictions to changes in the model parameters. The numerical results are in good agreement with analyses of the associated well-mixed model. Our model findings provide insight into how the nature of the contaminant and its initial density influence bacterial infection dynamics in the surgical wound.

Distant healing of surgical wounds: an exploratory study.

BACKGROUND: Distant healing intention (DHI) is one of the most common complementary and alternative medicine (CAM) healing modalities, but clinical trials to date have provided ambivalent support for its efficacy. One possible reason is that DHI effects may involve variables that are sensitive to unknown, uncontrolled, or uncontrollable factors. OBJECTIVE: To examine 2 of those potential variables-expectation and belief-we explored the effects of DHI on objective and psychosocial measures associated with surgical wounds in 72 women undergoing plastic surgery. DESIGN: Participants were randomly assigned to 1 of 3 groups: blinded and receiving DHI (DH), blinded and not receiving DHI (control), and knowing that they were receiving DHI (expectancy). Outcome measures included collagen deposition in a surrogate wound and several self-report measures. DHI was provided by experienced distant healers. No differences in the main measures were observed across the three groups. RESULTS: Participants' previous belief in the efficacy of DHI was negatively correlated with the status of their mental health at the end of the study (P = .04, 2-tailed), and healers' perceptions of the quality of their subjective "contact" with the participants were negatively correlated both with change in mood (P = .001) and with collagen deposition (P = .04). A post-hoc analysis found that among participants assigned to receive DHI under blinded conditions, those undergoing reconstructive surgery after breast cancer treatment reported significantly better change in mood than those who were undergoing purely elective cosmetic surgery (P = .004). CONCLUSION: If future DHI experiments confirm the post-hoc observations, then some of the ambiguity observed in earlier DHI studies may be attributable to interactions among participants' and healers' beliefs, their expectations, and their motivations.

High intraoperative inspired oxygen does not increase postoperative supplemental oxygen requirements.

BACKGROUND: Although a high fraction of inspired oxygen (FIO2) could reduce surgical site infection, there is concern it could increase postoperative pulmonary complications, including hypoxemia. Intraoperative positive end-expiratory pressure can improve postoperative pulmonary function. A practical measure of postoperative pulmonary function and the degree of hypoxemia is supplemental oxygen requirement. We performed a double-blind randomized 2 × 2 factorial study on the effects of intraoperative FIO2 0.3 versus more than 0.9 with and without positive end-expiratory pressure on the primary outcome of postoperative supplemental oxygen requirements in patients undergoing lower risk surgery. METHODS: After Institutional Review Board approval and consent, 100 subjects were randomized using computer-generated lists into four treatment groups (intraoperative FIO2 0.3 vs. more than 0.9, with and without 3-5 cm H2O positive end-expiratory pressure). Thirty minutes and 24 h after extubation, supplemental oxygen was discontinued. Arterial oxygen saturation by pulse oximetry was recorded 15 min later. If oxygen saturation decreased to less than 90%, supplemental oxygen was added incrementally to maintain saturation more than 90%. RESULTS: Nearly all subjects required supplemental oxygen in the postanesthesia care unit. Nonparametric Wilcoxon rank sum test demonstrated no statistically significant difference between groups in supplemental oxygen requirements at 45 min and 24 h after tracheal extubation (P = 0.56 and 0.98, respectively). CONCLUSIONS: Use of intraoperative FIO2 more than 0.9 was not associated with increased oxygen requirement, suggesting it does not induce postoperative hypoxemia beyond anesthetic induction and surgery. Therefore, it may be reasonable to use high inspired oxygen in surgical patients with relatively normal pulmonary function.

Changes in heel skin temperature under pressure in hip surgery patients.

OBJECTIVE: The aim of the study was to examine the effect of external pressure of the bed surface on heel skin temperature in adults in the first 3 days after hip surgery. DESIGN: A quasi-experimental study in a prospective, within-subjects, repeated-measures design. SETTING: This study was performed at 2 acute-care hospitals. PARTICIPANTS: Eighteen subjects (9 men and 9 women) with a mean age of 58.3 (±16.1) years were recruited after hip surgery at the 2 hospitals. METHODS: Temperature sensors were placed on the plantar surface of each foot, close to the heels. Measures were taken when the heels were (1) suspended above the bed surface for 20 minutes (preload), (2) on the bed surface for 15 minutes (loading), and (3) suspended again above the bed surface for 15 minutes (unloading). MAIN OUTCOME MEASURES: Heel skin temperature and demographic data. RESULTS: Heel temperature increased during loading and unloading in both legs on postoperative days 1 (P = .003) and 3 (P = .04) but not on postoperative day 2. Heel temperature in the nonoperative leg decreased in the first 3 minutes of unloading on postoperative days 2 (P = .02) and 3 (P = .01). CONCLUSION: Heel temperature increased with loading and unloading on postoperative days 1 and 3. Upon immediate unloading, hyperemic response was present only in the nonoperative leg. Keeping the heels off the bed surface at all times may avoid heel skin temperature changes and prevent tissue damage. Further research is needed to identify the mechanisms that explain the effect of external pressure on heel temperature.

Quantitative tissue oxygen measurement in multiple organs using 19F MRI in a rat model.

Measurement of individual organ tissue oxygen levels can provide information to help evaluate and optimize medical interventions in many areas including wound healing, resuscitation strategies, and cancer therapeutics. Echo planar (19) F MRI has previously focused on tumor oxygen measurement at low oxygen levels (pO(2)) <30 mmHg. It uses the linear relationship between spin-lattice relaxation rate (R(1)) of hexafluorobenzene (HFB) and pO(2). The feasibility of this technique for a wider range of pO(2) values and individual organ tissue pO(2) measurement was investigated in a rat model. Spin-lattice relaxation times (T(1) = 1/R(1)) of hexafluorobenzene were measured using (19) F saturation recovery echo planar imaging. Initial in vitro studies validated the linear relationship between R(1) and pO(2) from 0 to 760 mmHg oxygen partial pressure at 25, 37, and 41°C at 7 Tesla for hexafluorobenzene. In vivo experiments measured rat tissue oxygen (ptO2) levels of brain, kidney, liver, gut, muscle, and skin during inhalation of both 30 and 100% oxygen. All organ ptO(2) values significantly increased with hyperoxia (P < 0.001). This study demonstrates that (19) F MRI of hexafluorobenzene offers a feasible tool to measure regional ptO2 in vivo, and that hyperoxia significantly increases ptO2 of multiple organs in a rat model.

Monitoring partial and full venous outflow compromise in a rabbit skin flap model.

BACKGROUND: Free flap failure often results from venous thrombosis. The authors developed a rabbit flap model of partial venous obstruction and evaluated four monitoring devices in detecting partial and full venous compromise. METHODS: Nine skin flaps were elevated on their arteriovenous pedicles in rabbits. The flap was assessed with quantitative Doppler of arterial inflow, transcutaneous oxygen and carbon dioxide tension, near-infrared spectroscopy tissue oxygen saturation, and scanning laser Doppler imaging. After a stable baseline was achieved, the outflow vein was subjected to partial and full venous obstruction followed by release. RESULTS: Pedicle arterial flow decreased significantly from baseline (5.9 +/- 3.0 ml/minute) during partial (4.1 +/- 2.4 ml/minute; 30.5 percent; p < 0.01) and full obstruction (0.3 +/- 0.4 ml/minute; 94.9 percent; p < 0.01). All other measures changed significantly with full obstruction: transcutaneous oxygen tension decreased by 79.6 percent; transcutaneous carbon dioxide tension increased by 69.0 percent; near-infrared spectroscopy tissue oxygen saturation decreased by 35.7 percent; and scanning laser Doppler imaging decreased by 78.8 percent. Laser Doppler imaging was the only noninvasive device that decreased significantly (p < 0.01) with partial obstruction, from 222.8 +/- 77.3 units to 186.5 +/- 73.2 units (16.3 percent). CONCLUSIONS: The authors established a venous obstruction flap model and evaluated four clinically relevant monitoring devices during partial and full venous occlusion. All devices detected full occlusion, but only scanning laser Doppler imaging and arterial Doppler detected partial occlusion. Scanning laser Doppler imaging monitoring may allow warning of impending venous obstruction. Near-infrared spectroscopy tissue oxygen saturation varied the least between flaps and therefore may be the most easily interpreted device for full venous occlusion. Both characteristics are important for clinical application.

Hyperoxia and infection.

Surgical wound infection remains a common and serious complication of surgery. Patient factors are a major determinant of wound outcome following surgery. Co-morbidities clearly contribute, but environmental stressors as well the individual response to stress may be equally important. In particular, wounds are exquisitely sensitive to hypoxia, which is both common and preventable. Perioperative management can promote postoperative wound healing and resistance to infection. Maintaining perfusion and oxygenation of the wound is paramount. Once perfusion is assured, addition of increased inspired oxygen substantially reduces surgical site infection in at risk patients. A greater degree of hyperoxemia, achievable with administration of hyperbaric oxygen, is useful as an adjunct to the treatment of serious soft tissue and bone infections in selected patients. This article will review the basic science underlying these observations, along with the clinical data that support the use of hyperoxia in preventing and treating infections.

How heel oxygenation changes under pressure.

The mechanism of heel pressure ulcers after hip surgery is not entirely understood. The purpose of this one-group, prospective, repeated-measures design study was to examine how the external pressure of the bed surface affects heel skin oxygen tension in adults on the first 3 days after hip surgery. Transcutaneous oxygen sensors were placed on the plantar surface of each foot, close to the heels. Measures were taken on room air and with an oxygen challenge with the heels (1) suspended above the bed surface (preload), (2) on the bed surface for 15 minutes (loading), and (3) again suspended above the bed surface for 15 minutes (unloading). Eighteen hip surgery patients (mean age 58.3+/-16.1 years) from two hospitals participated. When compared with preload on room air, both loading and unloading on all 3 days resulted in a reduction in heel oxygen tension bilaterally (p<0.001). Heel oxygenation decreased without the anticipated hyperemic response, raising the question of whether this is a sign of increased pressure ulcer risk. Further work is needed to understand why this short period of external pressure results in decreased oxygenation and why oxygen tension does not return to baseline when pressure is removed.

HBO and gas embolism.

Gas embolism, which occurs with the entry of gas into the circulatory system from the vein, artery or both, is a potentially serious even fatal condition. The two main causes of gas embolism are iatrogenic and diving. The site of entry and the signs and symptoms distinguish between arterial and venous embolism. The entering gas may be air, but may also be CO(2) or other gases, especially in iatrogenic embolism. Supportive care is the primary therapy for venous gas embolism, while hyperbaric oxygen therapy in addition to supportive care is the first line of treatment for arterial gas embolism. In this article, we will review the pathophysiology, etiology, diagnosis and treatment of gas embolism.

Using physiology to improve surgical wound outcomes.

Despite major advances in surgical management and approaches, including aseptic techniques, prophylactic antibiotics, and laparoscopic surgery, surgical wound infection and wound failure remain common complications of surgery. In a review of the literature, the authors found that a growing body of literature supports the concept that patient factors are a major determinant of wound outcome after surgery. In particular, wounds are exquisitely sensitive to hypoxia, which is both common and preventable. Perioperative management can be adapted to promote postoperative wound healing and resistance to infection. The most important factors are fluid management, temperature management, pain control, increased arterial oxygen tension, and, as has been long recognized, appropriate sterile techniques and administration of prophylactic antibiotics. This article reviews how knowledge of and attention to physiology can improve quality of care in both acute and chronic wounds.

Hyperoxia and angiogenesis.

We hypothesized that tissue hyperoxia would enhance and hypoxia inhibit neovascularization in a wound model. Therefore, we used female Swiss-Webster mice to examine the influence of differential oxygen treatment on angiogenesis. One milliliter plugs of Matrigel, a mixture of matrix proteins that supports but does not itself elicit angiogenesis, were injected subcutaneously into the mice. Matrigel was used without additive or with added vascular endothelial growth factor (VEGF) or anti-VEGF antibody. Animals were maintained in hypoxic, normoxic, or one of four hyperoxic environments: hypoxia -- 13 percent oxygen at 1 atmosphere absolute (ATA); normoxia -- 21 percent oxygen at 1 ATA; hyperoxia -- (groups a-d) 100 percent oxygen for 90 minutes twice daily at the following pressures: Group a, 1 ATA; Group b, 2 ATA; Group c, 2.5 ATA; Group d, 3.0 ATA. Subcutaneous oxygen tension was measured in all groups. The Matrigel was removed 7 days after implantation. Sections were graded microscopically for the extent of neovascularization. Angiogenesis was significantly greater in all hyperoxic groups and significantly less in the hypoxic group compared with room air-exposed controls. Anti-VEGF antibody abrogated the angiogenic effect of both VEGF and increased oxygen tension. We conclude that angiogenesis is proportional to ambient pO(2) over a wide range. This confirms the clinical impression that angiogenesis requires oxygen. Intermittent oxygen exposure can satisfy the need for oxygen in ischemic tissue.