Mortality and Severe Complications Among Newly Graduated Surgeons in the United States

OBJECTIVE

To evaluate severe complications and mortality over years of independent practice among general surgeons.

BACKGROUND

Despite concerns that newly graduated general surgeons may be unprepared for independent practice, it is unclear whether patient outcomes differ between early and later career surgeons.

METHODS

We used Medicare claims for patients discharged between July 1, 2007 and December 31, 2019 to evaluate 30-day severe complications and mortality for 26 operations defined as core procedures by the American Board of Surgery. Generalized additive mixed models were used to assess the association between surgeon years in practice and 30-day outcomes while adjusting for differences in patient, hospital, and surgeon characteristics.

RESULTS

The cohort included 1,329,358 operations performed by 14,399 surgeons. In generalized mixed models, the relative risk (RR) of mortality was higher among surgeons in their first year of practice compared with surgeons in their 15th year of practice [5.5% (95% CI: 4.1%-7.3%) vs 4.7% (95% CI: 3.5%-6.3%), RR: 1.17 (95% CI: 1.11-1.22)]. Similarly, the RR of severe complications was higher among surgeons in their first year of practice compared with surgeons in their 15th year of practice [7.5% (95% CI: 6.6%-8.5%) versus 6.9% (95% CI: 6.1%-7.9%), RR: 1.08 (95% CI: 1.03-1.14)]. When stratified by individual operation, 21 operations had a significantly higher RR of mortality and all 26 operations had a significantly higher RR of severe complications in the first compared with the 15th year of practice.

CONCLUSIONS

Among general surgeons performing common operations, rates of mortality and severe complications were higher among newly graduated surgeons compared with later career surgeons.

Outcomes of Emergency Parastomal Hernia Repair in Older Adults: A Retrospective Analysis

INTRODUCTION

Parastomal hernias are common and many are never repaired. Emergency parastomal hernia repair (PHR) is a feared complication following ostomy creation, yet the incidence and long-term outcomes of emergency PHR are unknown.

MATERIALS AND METHODS

We performed a retrospective analysis of 100% Medicare claims data (2007-2015) to evaluate complications, readmissions, reoperations, hospitalizations, and mortality after emergency PHR. We used logistic regression and Cox proportional hazard models to determine the association of surgical approach, including repair with ostomy reversal, resiting, mesh, minimally invasive approach, or a myofascial flap. Analysis took place between June 2022 and February 2023.

RESULTS

A total of 6658 patients underwent emergency PHR (mean [standard deviation] age, 75.9 [9.8] y; 4031 female individuals [60.5%]). Overall, 3433 (51.2%) patients underwent primary PHR, 1626 (24.4%) underwent PHR with ostomy resiting, and 1599 (24.0%) underwent PHR with ostomy reversal. In the 30 d after surgery, 4151 (62.3%) patients had complications and 55 (0.83%) underwent reoperation. Compared to local repair, the 30-d odds of complications were lower for patients who underwent ostomy resiting (odds ratio 0.82 [95% confidence interval 0.72-0.93]). Five y after surgery, the cumulative incidence of reoperation was 12.0% and was lowest for patients who underwent PHR with ostomy reversal (hazard ratio 0.15 [95% confidence interval 0.11-0.21]) when compared to local repair.

CONCLUSIONS

Emergency PHR is associated with significant morbidity. However, technique selection may influence outcomes. Understanding the prognosis of emergency PHR may improve decision-making and patient counseling for patients living with this common disease.

Use of statewide financial incentives to improve documentation of hernia and mesh characteristics in ventral hernia repair

BACKGROUND

Documentation of intraoperative details is critical for understanding and advancing hernia care, but is inconsistent in practice. Therefore, to improve data capture on a statewide level, we implemented a financial incentive targeting documentation of hernia defect size and mesh use.

METHODS

The Abdominal Hernia Care Pathway (AHCP), a voluntary pay for performance (P4P) initiative, was introduced in 2021 within the statewide Michigan Surgical Quality Collaborative (MSQC). This consisted of an organizational-level financial incentive for achieving 80% performance on eight specific process measures for ventral hernia surgery, including complete documentation of hernia defect size and location, as well as mesh characteristics and fixation technique. Comparisons were made between AHCP and non-AHCP sites in 2021.

RESULTS

Of 69 eligible sites, 47 participated in the AHCP in 2021. There were N = 5362 operations (4169 at AHCP sites; 1193 at non-AHCP sites). At AHCP sites, 69.8% of operations had complete hernia documentation, compared to 50.5% at non-AHCP sites (p < 0.0001). At AHCP sites, 91.4% of operations had complete mesh documentation, compared to 86.5% at non-AHCP sites (p < 0.0001). The site-level hernia documentation goal of 80% was reached by 14 of 47 sites (range 14-100%). The mesh documentation goal was reached by 41 of 47 sites (range 4-100%).

CONCLUSIONS

Addition of an organizational-level financial incentive produced marked gains in documentation of intra-operative details across a statewide surgical collaborative. The relatively large effect size-19.3% for hernia-is remarkable among P4P initiatives. This result may have been facilitated by surgeons' direct role in documenting hernia size and mesh use. These improvements in data capture will foster understanding of current hernia practices on a large scale and may serve as a model for improvement in collaboratives nationally.

Evaluating Educational Outcomes Using Patient Outcomes of New Surgeons Performing Partial Colectomy Compared to Cholecystectomy

PURPOSE

Despite ongoing efforts to improve surgical education, surgical residents face gaps in their training. However, it is unknown if differences in the training of surgeons are reflected in the patient outcomes of those surgeons once they enter practice. This study aimed to compare the patient outcomes among new surgeons performing partial colectomy-a common procedure for which training is limited-and cholecystectomy-a common procedure for which training is robust.

METHOD

The authors retrospectively analyzed all adult Medicare claims data for patients undergoing inpatient partial colectomy and inpatient cholecystectomy between 2007 and 2018. Generalized additive mixed models were used to investigate the associations between surgeon years in practice and risk-adjusted rates of 30-day serious complications and death for patients undergoing partial colectomy and cholecystectomy.

RESULTS

A total of 14,449 surgeons at 4,011 hospitals performed 340,114 partial colectomy and 355,923 cholecystectomy inpatient operations during the study period. Patients undergoing a partial colectomy by a surgeon in their 1st vs 15th year of practice had higher rates of serious complications (5.22% [95% CI, 4.85%-5.60%] vs 4.37% [95% CI, 4.22%-4.52%]; P < .01) and death (3.05% [95% CI, 2.92%-3.17%] vs 2.83% [95% CI, 2.75%-2.91%]; P < .01). Patients undergoing a cholecystectomy by a surgeon in their 1st vs 15th year of practice had similar rates of 30-day serious complications (4.11% vs 3.89%; P = .11) and death (1.71% vs 1.70%; P = .93).

CONCLUSIONS

Patients undergoing partial colectomy faced a higher risk of serious complications and death when the operation was performed by a new surgeon compared to an experienced surgeon. Conversely, patient outcomes following cholecystectomy were similar for new and experienced surgeons. More attention to partial colectomy during residency training may benefit patients.

Prescribed Opioid Dosages, Payer Type, and Self-Reported Outcomes After Surgical Procedures in Michigan, 2018-2020

Importance

Collaborative quality improvement (CQI) models, often supported by private payers, create hospital networks to improve health care delivery. Recently, these systems have focused on opioid stewardship; however, it is unclear whether reduction in postoperative opioid prescribing occurs uniformly across health insurance payer types.

Objective

To evaluate the association between insurance payer type, postoperative opioid prescription size, and patient-reported outcomes in a large statewide CQI model.

Design, Setting, and Participants

This retrospective cohort study used data from 70 hospitals within the Michigan Surgical Quality Collaborative clinical registry for adult patients (age ≥18 years) undergoing general, colorectal, vascular, or gynecologic surgical procedures between January 1, 2018, and December 31, 2020.

Exposure

Insurance type, classified as private, Medicare, or Medicaid.

Main Outcomes and Measures

The primary outcome was postoperative opioid prescription size in milligrams of oral morphine equivalents (OME). Secondary outcomes were patient-reported opioid consumption, refill rate, satisfaction, pain, quality of life, and regret about undergoing surgery.

Results

A total of 40 149 patients (22 921 [57.1%] female; mean [SD] age, 53 [17] years) underwent surgery during the study period. Within this cohort, 23 097 patients (57.5%) had private insurance, 10 667 (26.6%) had Medicare, and 6385 (15.9%) had Medicaid. Unadjusted opioid prescription size decreased for all 3 groups during the study period from 115 to 61 OME for private insurance patients, from 96 to 53 OME for Medicare patients, and from 132 to 65 OME for Medicaid patients. A total of 22 665 patients received a postoperative opioid prescription and had follow-up data for opioid consumption and refill. The rate of opioid consumption was highest among Medicaid patients throughout the study period (16.82 OME [95% CI, 12.57-21.07 OME] greater than among patients with private insurance) but increased the least over time. The odds of refill significantly decreased over time for patients with Medicaid compared with patients with private insurance (odds ratio, 0.93; 95% CI, 0.89-0.98). Adjusted refill rates for private insurance remained between 3.0% and 3.1% over the study period; adjusted refill rates among Medicare and Medicaid patients decreased from 4.7% to 3.1% and 6.5% to 3.4%, respectively, by the end of the study period.

Conclusions and Relevance

In this retrospective cohort study of surgical patients in Michigan from 2018 to 2020, postoperative opioid prescription size decreased across all payer types, and differences between groups narrowed over time. Although funded by private payers, the CQI model appeared to have benefitted patients with Medicare and Medicaid as well.

Association Between Loneliness and Postoperative Mortality Among Medicare Beneficiaries

This cohort study uses data from the Health and Retirement Study and Medicare claims to examine the association between loneliness and postoperative mortality after elective vs nonelective surgery among older adults.

Association of Postoperative Opioid Prescription Size and Patient Satisfaction

OBJECTIVE

To evaluate the association between postoperative opioid prescription size and patient-reported satisfaction among surgical patients.

SUMMARY BACKGROUND DATA

Opioids are overprescribed after surgery, which negatively impacts patient outcomes. The assumption that larger prescriptions increase patient satisfaction has been suggested as an important driver of excessive prescribing.

METHODS

This prospective cohort study evaluated opioid-naive adult patients undergoing laparoscopic cholecystectomy, laparoscopic appendectomy, and minor hernia repair between January 1 and May 31, 2018. The primary outcome was patient satisfaction, collected via a 30-day postoperative survey. Satisfaction was measured on a scale of 0 to 10 and dichotomized into "highly satisfied" (9-10) and "not highly satisfied" (0-8). The explanatory variable of interest was size of opioid prescription at discharge from surgery, converted into milligrams of oral morphine equivalents (OME). Hierarchical logistic regression was performed to evaluate the association between prescription size and satisfaction while adjusting for clinical covariates.

RESULTS

One thousand five hundred twenty patients met the inclusion criteria. Mean age was 53 years and 43% of patients were female. One thousand two hundred seventy-nine (84.1%) patients were highly satisfied and 241 (15.9%) were not highly satisfied. After multivariable adjustment, there was no significant association between opioid prescription size and satisfaction (OR 1.00, 95% CI 0.99-1.00). The predicted probability of being highly satisfied ranged from 83% for the smallest prescription (25 mg OME) to 85% for the largest prescription (750 mg OME).

CONCLUSIONS

In a large cohort of patients undergoing common surgical procedures, there was no association between opioid prescription size at discharge after surgery and patient satisfaction. This implies that surgeons can provide significantly smaller opioid prescriptions after surgery without negatively affecting patient satisfaction.

Opioid prescribing exceeds consumption following common surgical oncology procedures

BACKGROUND AND OBJECTIVES

Surgical oncology patients are vulnerable to persistent opioid use. As such, we aim to compare opioid prescribing to opioid consumption for common surgical oncology procedures.

METHODS

We prospectively identified patients undergoing common surgical oncology procedures at a single academic institution (August 2017-March 2018). Patients were contacted by telephone within 6 months of surgery and asked to report their opioid consumption and describe their discharge instructions and opioid handling practices.

RESULTS

Of the 439 patients who were approached via telephone, 270 completed at least one survey portion. The median quantity of opioid prescribed was significantly larger than consumed following breast biopsy (5 vs. 2 tablets of 5 mg oxycodone, p < .001), lumpectomy (10 vs. 2 tablets of 5 mg oxycodone, p < .001), and mastectomy or wide local excision (20 tablets vs. 2 tablets of 5 mg oxycodone, p < .001). The majority of patients reported receiving education on taking opioids, but only 27% received instructions on proper disposal; 82% of prescriptions filled resulted in unused opioids, and only 11% of these patients safely disposed of them.

CONCLUSIONS

This study demonstrates that opioid prescribing exceeds consumption following common surgical oncology procedures, indicating the potential for reductions in prescribing.

Assessment of a quality improvement intervention to decrease opioid prescribing in a regional health system

BACKGROUND

Opioids are prescribed in excess after surgery. We leveraged our continuous quality improvement infrastructure to implement opioid prescribing guidelines and subsequently evaluate changes in postoperative opioid prescribing, consumption and patient satisfaction/pain in a statewide regional health system.

METHODS

We collected data regarding postoperative prescription size, opioid consumption and patient-reported outcomes from February 2017 to May 2019, from a 70-hospital surgical collaborative. Three iterations of prescribing guidelines were released. An interrupted time series analysis before and after each guideline release was performed. Linear regression was used to identify trends in consumption and patient-reported outcomes over time.

RESULTS

We included 36 022 patients from 69 hospitals who underwent one of nine procedures in the guidelines, of which 15 174 (37.3%) had complete patient-reported outcomes data following surgery. Before the intervention, prescription size was decreasing over time (slope: -0.7 tablets of 5 mg oxycodone/month, 95% CI -1.0 to -0.5 tablets, p<0.001). After the first guideline release, prescription size declined by -1.4 tablets/month (95% CI -1.8 to -1.0 tablets, p<0.001). The difference between these slopes was significant (p=0.006). The second guideline release resulted in a relative increase in slope (-0.3 tablets/month, 95% CI -0.1 to -0.6, p<0.001). The third guideline release resulted in no change (p=0.563 for the intervention). Overall, mean (SD) prescription size decreased from 25 (17) tablets of 5 mg oxycodone to 12 (8) tablets. Opioid consumption also decreased from 11 (16) to 5 (7) tablets (p<0.001), while satisfaction and postoperative pain remained unchanged.

CONCLUSIONS

The use of procedure-specific prescribing guidelines reduced statewide postoperative opioid prescribing by 50% while providing satisfactory pain care. These results demonstrate meaningful impact on opioid prescribing using evidence-based best practices and serve as an example of successful utilisation of a regional health collaborative for quality improvement.

Spillover Effect of Opioid Reduction Interventions From Adult to Pediatric Surgery

BACKGROUND

Procedure-specific prescribing guidelines and trainee education have reduced opioid overprescribing in adult surgical patients, but tailored interventions do not yet exist for children. It is unknown what effect these adult interventions have had on postoperative opioid prescribing in children at the same institution, where trainees rotate across both adult and pediatric services.

MATERIALS AND METHODS

This retrospective study of patients (<18 y) undergoing pediatric surgery (PS), pediatric otolaryngology (ENT), or pediatric urology (URO) procedures at a single tertiary academic center assessed opioid doses per patient before (January 01, 2015 to September 30, 2016) and after (January 01, 2017 to March 31, 2018) opioid prescribing guidelines and trainee education were instituted for adult laparoscopic cholecystectomy. Patient demographics, postoperative opioid prescribing, opioid refills, and emergency department (ED) visits <21 d after surgery were compared using chi-squared analyses and t-tests. Interrupted time-series analyses (ITSA) assessed changes in the rate of opioid prescribing pre- and postintervention for each subspecialty.

RESULTS

There were 3371 patients preintervention and 2439 patients postintervention. After the intervention, fewer patients were prescribed opioids (ENT: 97% versus 93%, P < 0.001; URO: 98% versus 94%, P < 0.001; PS: 61% versus 25%, P < 0.001) and fewer opioid doses were prescribed in each prescription (ENT: 63.8 ± 26.1 versus 50.8 ± 22.0 doses, P < 0.001; URO: 33.5 ± 23.4 versus 22.1 ± 11.3, P < 0.001; PS: 20.4 ± 12.8 versus 13.8 ± 11.4 doses, P < 0.001). There were no changes in opioid refill or ED visit rates postintervention. A decreasing rate in ENT prescribing was seen preintervention, with no significant change postintervention (-2.3 ± 1.1 versus -3.3 ± 0.7; P = 0.24). Whereas, the rate of decrease in PS and URO prescribing significantly slowed postintervention (PS: -2.0 ± 0.1 versus -0.9 ± 0.1, P < 0.001; URO: -4.2 ± 0.2 versus -2.3 ± 0.5, P = 0.005).

CONCLUSIONS

Opioid prescribing rates are decreasing, but adult interventions did not achieve reductions in pediatric opioid prescribing at the same institution. There was no concomitant rise in postoperative ED visits or opioid refills as prescribing declined, indicating that the risks of reducing opioid prescriptions may be minimal. Development of evidence-based, procedure-specific prescribing guidelines that specifically address pediatric patients are needed to effectively minimize opioid overprescribing in this population.

Near-Sun observations of an F-corona decrease and K-corona fine structure

Remote observations of the solar photospheric light scattered by electrons (the K-corona) and dust (the F-corona or zodiacal light) have been made from the ground during eclipses¹ and from space at distances as small as 0.3 astronomical units^2-5 to the Sun. Previous observations^6-8 of dust scattering have not confirmed the existence of the theoretically predicted dust-free zone near the Sun^9-11. The transient nature of the corona has been well characterized for large events, but questions still remain (for example, about the initiation of the corona¹² and the production of solar energetic particles¹³) and for small events even its structure is uncertain¹⁴. Here we report imaging of the solar corona¹⁵ during the first two perihelion passes (0.16-0.25 astronomical units) of the Parker Solar Probe spacecraft¹³, each lasting ten days. The view from these distances is qualitatively similar to the historical views from ground and space, but there are some notable differences. At short elongations, we observe a decrease in the intensity of the F-coronal intensity, which is suggestive of the long-sought dust free zone^9-11. We also resolve the fine-scale plasma structure of very small eruptions, which are frequently ejected from the Sun. These take two forms: the frequently observed magnetic flux ropes^12,16 and the predicted, but not yet observed, magnetic islands^17,18 arising from the tearing-mode instability in the current sheet. Our observations of the coronal streamer evolution confirm the large-scale topology of the solar corona, but also reveal that, as recently predicted¹⁹, streamers are composed of yet smaller substreamers channelling continual density fluctuations at all visible scales.

The Impact of Education and Prescribing Guidelines on Opioid Prescribing for Breast and Melanoma Procedures

BACKGROUND

Excessive opioid prescribing is common in surgical oncology, with 72% of prescribed opioids going unused after curative-intent surgery. In this study, we sought to reduce opioid prescribing after breast and melanoma procedures by designing and implementing an intervention focused on education and prescribing guidelines, and then evaluating the impact of this intervention.

METHODS

In this single-institution study, we designed and implemented an intervention targeting key factors identified in qualitative interviews. This included mandatory education for prescribers, evidence-based prescribing guidelines, and standardized patient instructions. After the intervention, interrupted time-series analysis was used to compare the mean quantity of opioid prescribed before and after the intervention (July 2016-September 2017). We also evaluated the frequency of opioid prescription refills.

RESULTS

During the study, 847 patients underwent breast or melanoma procedures and received an opioid prescription. For mastectomy or wide local excision for melanoma, the mean quantity of opioid prescribed immediately decreased by 37% after the intervention (p = 0.03), equivalent to 13 tablets of oxycodone 5 mg. For lumpectomy or breast biopsy, the mean quantity of opioid prescribed decreased by 42%, or 12 tablets of oxycodone 5 mg (p = 0.07). Furthermore, opioid prescription refills did not significantly change for mastectomy/wide local excision (13% vs. 14%, p = 0.8), or lumpectomy/breast biopsy (4% vs. 5%, p = 0.7).

CONCLUSION

Education and prescribing guidelines reduced opioid prescribing for breast and melanoma procedures without increasing the need for refills. This suggests further reductions in opioid prescribing may be possible, and provides rationale for implementing similar interventions for other procedures and practice settings.

The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

Tonabersat, a gap-junction modulator: efficacy and safety in two randomized, placebo-controlled, dose-ranging studies of acute migraine

Tonabersat is a novel benzopyran derivative that blocks the cortical spreading depression proposed to be associated with migraine attacks. The ability of single oral doses of 15, 25, 40 and 80 mg of tonabersat to relieve the symptoms of moderate to severe migraine was evaluated in 859 migraineurs enrolled in two dose-ranging, double-blind, randomized, placebo-controlled, parallel-group trials, one international and the other North American. In the international study, significantly more patients given tonabersat than given placebo experienced relief of headache pain at 2 h (15 mg, 36.8%; 40 mg, 40.7%), the principal efficacy variable, and at 4 h (40 mg, 63.0%) and complete abolition of headache at 4 h (40 mg, 34.3%). None of the primary or secondary efficacy variables indicated significant differences between tonabersat and placebo in the North American study. Tonabersat was generally well tolerated, with dizziness and nausea the most common side-effects. Serious adverse events were uncommon, and no patient withdrew from either study because of adverse events. These results suggest a possible interplay between tonabersat pharmacokinetics (the relatively long time required to reach maximum plasma concentrations) and patient characteristics (previous triptan exposure) in the management of acute migraine attacks. Based on the pharmacokinetics and actions on cortical spreading depression, tonabersat may have potential value in migraine prophylaxis.

Reproduction of In Vivo Motion Using a Parallel Robot

Although alterations in knee joint loading resulting from injury have been shown to influence the development of osteoarthritis, actual in vivo loading conditions of the joint remain unknown. A method for determining in vivo ligament loads by reproducing joint specific in vivo kinematics using a robotic testing apparatus is described. The in vivo kinematics of the ovine stifle joint during walking were measured with 3D optical motion analysis using markers rigidly affixed to the tibia and femur. An additional independent single degree of freedom measuring device was also used to record a measure of motion. Following sacrifice, the joint was mounted in a robotic/universal force sensor test apparatus and referenced using a coordinate measuring machine. A parallel robot configuration was chosen over the conventional serial manipulator because of its greater accuracy and stiffness. Median normal gait kinematics were applied to the joint and the resulting accuracy compared. The mean error in reproduction as determined by the motion analysis system varied between 0.06mm and 0.67mm and 0.07deg and 0.74deg for the two individual tests. The mean error measured by the independent device was found to be 0.07mm and 0.83mm for the two experiments, respectively. This study demonstrates the ability of this system to reproduce in vivo kinematics of the ovine stifle joint in vitro. The importance of system stiffness is discussed to ensure accurate reproduction of joint motion.

A potential animal model for creating a controlled and reversible anterior cruciate ligament insufficiency

We developed and tested a device to manipulate the axial position of the tibial anterior cruciate ligament (ACL) insertion in vitro to create a potential animal model that could simulate both ACL insufficiency and 'optimal' ACL reconstruction. This model is based on the concept that controlled incremental proximal displacement of the tibial ACL insertion simulates ACL insufficiency. Replacing the insertion at the joint level and then adjusting its position until the forces recorded equaled those in the ACL-intact knee can simulate 'optimal' ACL reconstruction. Anterior tibial translation (ATT) was quantified in vitro in 24 sheep cadaver knees with the ACL intact and after the ACL was cut or detached (ACL insufficiency). In 8 knees, a bone plug including the tibial ACL insertion was detached, mounted in a specially designed device, and adjusted to reproduce ATT of the ACL-intact knee. ATT was then measured after proximal displacement of the tibial ACL insertion in calibrated 1 mm increments. The results revealed that detaching the ACL increased ATT by 132-700%. Controlled 3 mm proximal displacement of the insertion using this device increased ATT by more than 100%. Comparing the increase in ATT due to controlled displacement of the ACL insertion to that due to detaching the ACL, in only one case was the same magnitude of ACL insufficiency reproduced. Despite the variability between knees, the device was able to reproduce ATT of the ACL-intact knee and to substantially increase ATT with controlled proximal displacement of the tibial ACL insertion. Use of this device, if successful in an in vivo ACL reconstruction model, could help define any quantitative association between altered joint kinematics and degenerative changes in the joint.

Symptomatic hypotension during arm cycle ergometry exercise: a report of five cases

We report five cases of vasovagal and vasodepressor syncope or near-syncope that occurred during arm cycle ergometry. In each case, arm exercise in the seated position had been performed immediately after dynamic leg exercise. A likely mechanism involves a decrease in preload from venous pooling of blood in the lower extremities after leg exercise, and excessive stimulation of ventricular mechanoreceptors with resultant sympatho-inhibition and enhanced vagal tone. Four of the cases occurred early in the course of the exercise program, between the 8th and 10th sessions. The single case of true syncope occurred in a patient not receiving a beta-receptor blocking medication. No further events occurred when the exercise regimen was changed such that arm cycle ergometry was performed before leg exercise. We recommend that when arm ergometry is incorporated into an exercise program: (1) a cool-down period of exercise is performed after dynamic leg exercise, or (2) arm exercise is performed before dynamic leg exercise. These maneuvers may preclude the occurrence of symptomatic hypotension.

Papillary fibroelastoma: increasing recognition of a surgical disease

Papillary fibroelastomas are uncommon benign tumors usually involving the heart valves, which historically have been diagnosed at autopsy. With the advent of echocardiography, however, the number of patients diagnosed in life has increased. Papillary fibroelastomas represent a surgically treatable cause of cerebrovascular and cardiovascular ischemia and infarction making their identification clinically important. We report three unusual cases of papillary fibroelastoma; two patients presenting with symptoms of cerebrovascular ischemia and one presenting with myocardial infarction. We also present a comprehensive review of the literature and provide a compilation of all case reports to date.

Effect of epinephrine on intrathecal fentanyl analgesia in patients undergoing postpartum tubal ligation

Eighty women receiving spinal anesthesia for postpartum tubal ligation were entered into a double-blind, randomized protocol studying the effects of epinephrine on intrathecal fentanyl-induced postoperative analgesia. All patients received 70 mg hyperbaric lidocaine with either 0.2 mg epinephrine (LE), 10 micrograms fentanyl (LF), epinephrine and fentanyl (LFE), or 0.4 ml saline (L). Onset and regression of anesthesia, degree of intraoperative comfort, incidence of pruritus, and extent of postoperative analgesia were evaluated. The simultaneous administration of epinephrine and fentanyl prolonged the duration of complete analgesia (137 +/- 47 min (LFE); 76 +/- 32 min (LE); 85 +/- 44 min (LF); 65 +/- 36 min (L)) and the duration of effective analgesia (562 +/- 504 min (LFE); 227 +/- 201 min (LE); 203 +/- 178 min (LF); 198 +/- 342 min (L)). Administration of epinephrine decreased the incidence of pruritus associated with intrathecal fentanyl (1/18 (LFE); 1/21 (LE); 8/19 (LF); 2/19 (L)).

Microrisks for medical decision analysis

Many would agree on the need to inform patients about the risks of medical conditions or treatments and to consider those risks in making medical decisions. The question is how to describe the risks and how to balance them with other factors in arriving at a decision. In this article, we present the thesis that part of the answer lies in defining an appropriate scale for risks that are often quite small. We propose that a convenient unit in which to measure most medical risks is the microprobability, a probability of 1 in 1 million. When the risk consequence is death, we can define a micromort as one microprobability of death. Medical risks can be placed in perspective by noting that we live in a society where people face about 270 micromorts per year from interactions with motor vehicles. Continuing risks or hazards, such as are posed by following unhealthful practices or by the side-effects of drugs, can be described in the same micromort framework. If the consequence is not death, but some other serious consequence like blindness or amputation, the microrisk structure can be used to characterize the probability of disability. Once the risks are described in the microrisk form, they can be evaluated in terms of the patient's willingness-to-pay to avoid them. The suggested procedure is illustrated in the case of a woman facing a cranial arteriogram of a suspected arterio-venous malformation. Generic curves allow such analyses to be performed approximately in terms of the patient's sex, age, and economic situation. More detailed analyses can be performed if desired. Microrisk analysis is based on the proposition that precision in language permits the soundness of thought that produces clarity of action and peace of mind.

Correlation between effects of acute acetazolamide administration to mice on electroshock seizure threshold and maximal electroshock seizure pattern, and on carbonic anhydrase activity in subcellular fractions of brain

The relationships between inhibition of carbonic anhydrase (CA) activity in cytoplasmic, microsomal, and myelin subcellular fractions obtained from cerebral cortex, subcortex, and cerebellum and electroshock seizure threshold (EST) and modification of the extension/flexion (E/F) ratio following maximal electroshock seizures (MES) were ascertained in Swiss-Webster mice given 40 and 200 mg/kg acetazolamide. The parameters were determined at 1, 4, and 24 h after administration of acetazolamide. The results showed that changes in the E/F ratio induced by acetazolamide correlated linearly (r = 0.90) with changes in CA activity in the cytoplasm of the subcortex. However, there was an inverse power function correlation (r = 0.92) between EST and CA activity in the myelin fraction of the cerebral cortex. The time course of acetazolamide inhibition of CA activity in these two fractions also paralleled the time course of its effects on EST and E/F ratio. Thus, acetazolamide decreases susceptibility to seizures (raises EST) by inhibiting myelin CA and prevents spread of seizure activity by inhibiting CA in the cytoplasm of glial cells. The CO2 that accumulates as a result of CA inhibition in these two fractions causes profound changes in brain function.

Observations of a comet on collision course with the sun

A brilliant new comet (1979 XI: Howard-Koomen-Michels) was discovered in data from the Naval Research Laboratory's orbiting SOLWIND coronagraph. An extensive sequence of pictures, telemetered from the P78-1 satellite, shows the coma, accompanied by a bright and well-developed tail, passing through the coronagraph's field of view at afew million kilometers from the sun. Preliminary orbital calculations based on the observed motion of the comet's head and morphology of the tail indicate that this previously unreported object is a sungrazing comet and may be one of the group of Kreutz sungrazers. It appears from the data that the perihelion distance was less than 1 solar radius, so that the cometary nucleus encountered dense regions of the sun's atmosphere, was completely vaporized, and did not reappear after the time of closest approach to the sun. After this time, however, cometary debris, scattered into the ambient solar wind, caused a brightening of the corona over one solar hemisphere and to heliocentric distances of 5 to 10 solar radii.

Affinity labeling of a cysteine at or near the catalytic center of Escherichia coli B DNA-dependent RNA polymerase

9-beta-D-Arabinofuranosyl-6-thiopurine was used to affinity label DNA-dependent RNA polymerase isolated from Escherichia coli B. This substrate analogue displayed competitive type inhibition which could be reversed by addition of a thiol reagent, such as dithiothreitol, while exposure to hydrogen peroxide, a mild oxidizing agent, caused an increase in both the inhibitory and enzyme binding capability of arabinofuranosyl thiopurine. Chromatographic analysis of the products obtained by pronase digestion of the 9-beta-D-arabinofuranosyl-6-[35S]thiopurine-enzyme complex suggests that disulfide bond formation occurs between the inhibitor and a cysteine residue located in or near the active center of the enzyme. In addition, polyacrylamide gel electrophoresis indicated that the arabinofuranosyl thiopurine moeity was bound to the beta' subunit of the enzyme.

The effect of verapamil on the gastrocnemius and soleus muscles of the cat in vivo

The effects of verapamil on the force of contraction of soleus and gastrocnemius muscles of the cat were examined in vivo. The rapid intra-arterial administration of verapamil (100-800 micrograms/kg) produced a dose-dependent increase in the contractile force of soleus and gastrocnemius muscles stimulated supramaximally via their nerves. Verapamil also potentiated twitch tension in d-tubocurarine-treated, directly stimulated soleus preparations. This agent had no effect, however, on the contractile force of 14- to 16-day chronically denervated, directly stimulated soleus muscle. Verapamil (400 microgram/kg, i.a.) also produced a significant increase in muscle action potential duration while having no effect on amplitudes, rise times or resting membrane potential. It is concluded that verapamil acts directly on innervated skeletal muscle to increase muscle force and it is suggested that the probable site of action is at the muscle membrane.

Subunit localizations of zinc(II) in DNA-dependent RNA polymerase from Escherichia coli B

RNA Polymerase holoenzyme and core enzyme from Escherichia coli B have been shown to contain two zinc ions. Flameless atomic absorption spectroscopy of the isolated core subunits indicated that one zinc ion is localized on the beta subunit and the other is bound on the beta' subunit. Atomic fluorescence spectroscopy showed that prolonged dialysis of the metalloenzyme against 0.01 M o-phenanthroline resulted in the removal of both zinc(II) ions with accompanying loss of enzymatic activity. The activity of the apoenzyme was observed to be completely restored by readdition of zinc(II) and partially restored by cobalt(II).

Mechanism of action of tetra-mu-carboxylatodirhodium(II) in L1210 tumor suspension culture

The effect of tetrakis-mu-methoxyacetato, tetra-mu-acetato, tetra-mu-propionato, and tetra-mu-butyratodirhodium(II) on the proliferation and macromolecular synthesis of leukemia L1210 cells in suspension culture was evaluated. The cytotoxicity of these dimeric rhodium(II) complexes to tumor cells in suspension culture follows the same trend as observed in vivo, i.e., butyrato greater than propionato greater than acetato greater than methoxyacetato. The cellular synthesis of DNA and protein was found to be strongly inhibited by tetra-mu-propionatodirhodium(II), whereas minimal inhibition of RNA synthesis was observed. Flow microfluorometric analysis of the drug-treated cells revealed an arrest of cellular development during the G2 phase of the cell cycle. The inhibition of DNA synthesis was attributed at least in part to the arrest in G2 which is consistent with the observed inhibition of protein synthesis.

Hydrophobicity of several rhodium(II) carboxylates correlated with their biologic activity

Rhodium(II) carboxylates differ greatly in antitumor activity and toxicity depending on the properties of the carboxylate group (methoxyacetate, propionate, butyrate, etc.) involved. The solubility characteristics of rhodium(II) carboxylates correlate well with both the antitumor activity and toxicity that these compounds display. The amount of rhodium which is adsorbed by tumor cells in vitro also correlates with the partition coefficient of the rhodium(II) compounds studied. Survival and toxicity studies show rhodium(II) pentanoate to possess the highest therapeutic index against the Ehrlich ascites tumor strain and also show that lengthening the carboxylate R chain beyond the pentanoate reduces the drugs' therapeutic efficacy.

The interaction of rhodium(II) carboxylates with enzymes

The effect of rhodium(II) acetate, propionate, and methoxyacetate on the activity of 17 enzymes was evaluated. The enzymes were preincubated with the rhodium(II) complexes in order to detect irreversible inhibition. All enzymes that have essential sulfhydryl groups in or near their active site were found to be irreversibly inhibited. Those enzymes without essential sulfhydryl groups were not affected. In each case, the rate of inactivation closely paralleled the observed toxicity and antitumor activity of rhodium(II) carboxylates; that is, rhodium(II) propionate greater than rhodium(II) acetate greater than rhodium(II) methoxyacetate. In addition, those enzymes that have been demonstrated to be most sensitive to established sulfhydryl inhibitors, such as glyceraldehyde-3-phosphate dehydrogenase, were also most sensitive to rhodium(II) carboxylate inactivation. Proton nuclear magnetic resonance measurements made during the titration of rhodium(II) acetate with cysteine showed that breakdown of the carboxylate cage occurred as a result of reaction with this sulfhydryl-containing amino acid.