Opportunities for shared decision-making about major surgery with high-risk patients: a multi-method qualitative study.

BACKGROUND: Little is known about the opportunities for shared decision-making when older high-risk patients are offered major surgery. This study examines how, when, and why clinicians and patients can share decision-making about major surgery. METHODS: This was a multi-method qualitative study, combining video recordings of preoperative consultations, interviews, and focus groups (33 patients, 19 relatives, 36 clinicians), with observations and documentary analysis in clinics in five hospitals in the UK undertaking major orthopaedic, colorectal, and/or cardiac surgery. RESULTS: Three opportunities for shared decision-making about major surgery were identified. Resolution-focused consultations (cardiac/colorectal) resulted in a single agreed preferred option related to a potentially life-threatening problem, with limited opportunities for shared decision-making. Evaluative and deliberative consultations offered more opportunity. The former focused on assessing the likelihood of benefits of surgery for a presenting problem that was not a threat to life for the patient (e.g., orthopaedic consultations) and the latter (largely colorectal) involved discussion of a range of options while also considering significant comorbidities and patient preferences. The extent to which opportunities for shared decision-making were available, and taken up by surgeons, was influenced by the nature of the presenting problem, clinical pathway, and patient trajectory. CONCLUSIONS: Decisions about major surgery were not always shared between patients and doctors. The nature of the presenting problem, comorbidities, clinical pathways, and patient trajectories all informed the type of consultation and opportunities for sharing decision-making. Our findings have implications for clinicians, with shared decision-making about major surgery most feasible when the focus is on life-enhancing treatment.

Predictors of Failure in Fast-Track Cardiac Surgery.

OBJECTIVES: Fast-track (FT) management of cardiac surgery patients is associated with early extubation and reduced length of intensive care unit (ICU) stay, with potential benefit of reduced hospital costs. The authors examined perioperative factors and their influence on failure of FT and what implications this failure had. DESIGN: Prospective data collection from all adult cardiac surgeries between 2011 and 2013. SETTING: Single-institution study. PARTICIPANTS: The study included 2,770 consecutive adult cardiac surgery patients. INTERVENTIONS: All participants underwent adult cardiac surgeries. Of those, 451 (16.3%) patients were selected to undergo FT management. MEASUREMENTS AND MAIN RESULTS: Failure of FT was defined as early (admission to ICU on day of surgery) or late (patients later admitted to the ICU from the ward). Univariate and multivariate regression analyses were used to identify which variables predicted FT failure. Of the 451 patients included in this study, 138 (30.6%) failed the FT, with 115 (83.3%) early failures and 23 (16.7%) late failures. Predictors of failure were reduced renal function, hypertension, age, EuroSCORE, cardiopulmonary bypass time, first lactate or base deficit after surgery (all p<0.01), and cross-clamp time (p<0.05). Multivariate analysis showed that the strongest predictor of failure was glomerular filtration rate (GFR)<65 mL/min/BSA (sensitivity, 54%; specificity, 61%; likelihood ratio, 1.39; area under receiver operating characteristics curve, 0.59; 95% confidence interval, 0.53-0.64). Median length of hospital stay was longer for the failed group (5 v 7 days, p<0.001). There were no mortalities in any of the patients selected for FT. CONCLUSIONS: A number of perioperative factors are associated with failure to FT, the strongest predictor being GFR. Failure to FT can lead to significantly longer hospital stay.

Cerebral hemodynamics at altitude: effects of hyperventilation and acclimatization on cerebral blood flow and oxygenation.

OBJECTIVE: Alterations in cerebral blood flow (CBF) and cerebral oxygenation are implicated in altitude-associated diseases. We assessed the dynamic changes in CBF and peripheral and cerebral oxygenation engendered by ascent to altitude with partial acclimatization and hyperventilation using a combination of near-infrared spectroscopy, transcranial Doppler ultrasound, and diffuse correlation spectroscopy. METHODS: Peripheral (Spo2) and cerebral (Scto2) oxygenation, end-tidal carbon dioxide (ETCO2), and cerebral hemodynamics were studied in 12 subjects using transcranial Doppler and diffuse correlation spectroscopy (DCS) at 75 m and then 2 days and 7 days after ascending to 4559 m above sea level. After obtaining baseline measurements, subjects hyperventilated to reduce baseline ETCO2 by 50%, and a further set of measurements were obtained. RESULTS: Cerebral oxygenation and peripheral oxygenation showed a divergent response, with cerebral oxygenation decreasing at day 2 and decreasing further at day 7 at altitude, whereas peripheral oxygenation decreased on day 2 before partially rebounding on day 7. Cerebral oxygenation decreased after hyperventilation at sea level (Scto2 from 68.8% to 63.5%; P<.001), increased after hyperventilation after 2 days at altitude (Scto2 from 65.6% to 69.9%; P=.001), and did not change after hyperventilation after 7 days at altitude (Scto2 from 62.2% to 63.3%; P=.35). CONCLUSIONS: An intensification of the normal cerebral hypocapnic vasoconstrictive response occurred after partial acclimatization in the setting of divergent peripheral and cerebral oxygenation. This may help explain why hyperventilation fails to improve cerebral oxygenation after partial acclimatization as it does after initial ascent. The use of DCS is feasible at altitude and provides a direct measure of CBF indices with high temporal resolution.

Cerebral venous system and anatomical predisposition to high-altitude headache.

OBJECTIVE: As inspired oxygen availability falls with ascent to altitude, some individuals develop high-altitude headache (HAH). We postulated that HAH results when hypoxia-associated increases in cerebral blood flow occur in the context of restricted venous drainage, and is worsened when cerebral compliance is reduced. We explored this hypothesis in 3 studies. METHODS: In high-altitude studies, retinal venous distension (RVD) was ophthalmoscopically assessed in 24 subjects (6 female) and sea-level cranial magnetic resonance imaging was performed in 12 subjects ascending to 5,300m. Correlation of headache burden (summed severity scores [0-4]≤24 hours from arrival at each altitude) with RVD, and with cerebral/cerebrospinal fluid (CSF)/venous compartment volumes, was sought. In a sea-level hypoxic study, 11 subjects underwent gadolinium-enhanced magnetic resonance venography before and during hypoxic challenge (fraction of inspired oxygen=0.11, 1 hour). RESULTS: In the high-altitude studies, headache burden correlated with both RVD (Spearman rho=0.55, p=0.005) and with the degree of narrowing of 1 or both transverse venous sinuses (r=-0.56, p=0.03). It also related inversely to both the lateral+third ventricle summed volumes (Spearman rho=-0.5, p=0.05) and pericerebellar CSF volume (r=-0.56, p=0.03). In the hypoxic study, cerebral and retinal vein engorgement were correlated, and rose as the combined conduit score fell (a measure of venous outflow restriction; r=-0.66, p<0.05 and r=-0.75, p<0.05, respectively). INTERPRETATION: Arterial hypoxemia is associated with cerebral and retinal venous distension, whose magnitude correlates with HAH burden. Restriction in cerebral venous outflow is associated with retinal distension and HAH. Limitations in cerebral venous efferent flow may predispose to headache when hypoxia-related increases in cerebral arterial flow occur.

High-intensity intermittent exercise increases pulmonary interstitial edema at altitude but not at simulated altitude.

OBJECTIVE: Ascent to high altitude leads to a reduction in ambient pressure and a subsequent fall in available oxygen. The resulting hypoxia can lead to elevated pulmonary artery (PA) pressure, capillary stress, and an increase in interstitial fluid. This fluid can be assessed on lung ultrasound (LUS) by the presence of B-lines. We undertook a chamber and field study to assess the impact of high-intensity exercise in hypoxia on the development of pulmonary interstitial edema in healthy lowlanders. METHODS: Thirteen volunteers completed a high-intensity intermittent exercise (HIIE) test at sea level, in acute normobaric hypoxia (12% O2, approximately 4090 m equivalent altitude), and in hypobaric hypoxia during a field study at 4090 m after 6 days of acclimatization. Pulmonary interstitial edema was assessed by the evaluation of LUS B-lines. RESULTS: After HIIE, no increase in B-lines was seen in normoxia, and a small increase was seen in acute normobaric hypoxia (2 ± 2; P < .05). During the field study at 4090 m, 12 participants (92%) demonstrated 7 ± 4 B-lines at rest, which increased to 17 ± 5 immediately after the exercise test (P < .001). An increase was evident in all participants. There was a reciprocal fall in peripheral arterial oxygen saturations (Spo2) after exercise from 88% ± 4% to 80% ± 8% (P < .01). B-lines and Spo2 in all participants returned to baseline levels within 4 hours. CONCLUSIONS: HIIE led to an increase in B-lines at altitude after subacute exposure but not during acute exposure at equivalent simulated altitude. This may indicate pulmonary interstitial edema.

Exercise limitation of acetazolamide at altitude (3459 m).

OBJECTIVE: To assess the effect of acetazolamide (Az) on exercise performance during early acclimatization to altitude. METHODS: Az (250 mg twice daily) or placebo was administered for 3 days in a double-blind, randomized manner followed by a rapid ascent to 3459 m in the Italian Alps. Twenty healthy adults (age range, 18-67 years) were tested at 60% of sea-level peak power output for 15 minutes on a bicycle ergometer after 16 to 27 hours of altitude exposure. Exercise performance was measured in relation to peripheral oxygen saturations measured from pulse oximetry (Spo2), Lake Louise acute mountain sickness (AMS) score, and perceived difficulty. RESULTS: At altitude, resting Spo2 was higher in the Az group compared with placebo (P < .001). The highest AMS scores were in 4 of the placebo individuals with the lowest resting Spo2 (P < .05). During the exercise test, Spo2 fell in all but 1 subject (P < .001) and was reduced more in the Az group (P < .01). Four Az and 1 placebo subject were unable to complete the exercise test; 4 of these 5 had the largest fall in Spo2. The perception of exercise difficulty was higher in the Az subjects compared with those taking the placebo (P < .01). There was an age relationship with exercise limitation; 4 of the 9 older than 50 years failed to complete the test whereas only 1 of 11 younger than 50 years failed, and there were no failures in the 6 younger than 30 years (P < .05). CONCLUSIONS: In this study group, and despite higher resting Spo2, Az may have compromised exercise at 3459 m altitude during early acclimatization, particularly in older subjects.

The Environmental Impact of a High-Altitude Medical Research Expedition.

Joyce, Kelsey E., Catherine A. Campbell, Arthur R. Bradwell, Samuel J.E. Lucas, Christopher T. Lewis, Rebekah A.I. Lucas, and Mark Edsell. The environmental impact of a high-altitude medical research expedition. High Alt Med Biol. 00:00-00, 2024. Introduction: Scientists must begin examining the environmental cost(s) of their research. The purpose of this study was to evaluate a component of the environmental impact of a high-altitude medical research expedition by totaling the carbon dioxide (CO2) emissions calculated from as many direct and indirect sources as possible. Methods: Eighteen individuals flew from London to Bagdogra (via Delhi), and then drove onward to Lachung (via Gangtok) where they began their ascent on foot to 4,800 m (Kanchenjunga National Park, Sikkim). Several research experiments were conducted throughout the expedition, which required use of a laboratory centrifuge, solid CO2 (specimen storage), rechargeable laptop computers and battery-powered oximeters. International Civil Aviation Organization calculators estimated aviation CO2 production. Land emissions were calculated for Mahindra vehicles. Solid waste was weighed and CO2 emissions estimated for its incineration. Results: Total CO2 emissions equated to ∼16.7 tonnes from the following sources: air and land transportation of expedition team (87.3%); sublimation and transportation of solid CO2 (7.7%), waste incineration (0.58%), generator transportation and gasoline (12 l) combustion (0.48%), and battery transportation (3.3%). Conclusions: Air travel contributed the most to the overall environmental cost of the research expedition. Further investigation is required to contextualize these findings in relation to lab-based alternative(s).

Using ultrasound lung comets in the diagnosis of high altitude pulmonary edema: fact or fiction?

High altitude pulmonary edema is a life-threatening condition that remains a concern for climbers and clinicians alike. Within the last decade, studies have shown ultrasonography to be valuable in the accurate diagnosis of a variety of lung pathologies, including cardiogenic pulmonary edema, pleural effusion, pneumothorax, and lung consolidation. Recently, studies conducted in remote areas have demonstrated that ultrasound lung comets can be used as a measure of subacute pulmonary edema and high altitude pulmonary edema in climbers ascending to altitude. This clinical review article provides an overview of lung ultrasonography and its relevance as a diagnostic aid to respiratory pathology. In addition, we describe a standardized technique for identifying ultrasound lung comets and its utility in recognizing the presence of extravascular lung water, as well as the results of studies that have used this approach at sea level and high altitude.

Early and long-term outcomes of conventional and valve-sparing aortic root replacement.

OBJECTIVE: To determine the early and long-term outcomes of conventional aortic root (ARR) and valve-sparing root replacement (VSRR) using a standard perioperative and operative approach. METHODS: We present prospectively collected data of 609 consecutive patients undergoing elective and urgent aortic root surgery (470 ARR, 139 VSRR) between 2006 and 2020. Primary outcomes were operative mortality and incidence of postoperative complications. Secondary outcomes were long-term survival and requirement for reintervention. Median follow-up was 7.6 years (range 0.5-14.5). RESULTS: 189 patients (31%) had bicuspid aortic valves and 17 (6.9%) underwent redo procedures. Median cross-clamp time was 88 (range 54-208) min with cardiopulmonary bypass of 108 (range 75-296) min. In-hospital mortality was 10 (1.6%), with transient ischaemic attacks/strokes occurring in 1.1%. In-hospital mortality for VSRR was 0.7%. 12 patients (2.0%) required a resternotomy for bleeding and 14 (2.3%) received haemofiltration. Intensive care unit and hospital stay were 1.7 and 7.0 days, respectively. During follow-up, redo surgery for native aortic valve replacement was required in 1.4% of the VSRR group. Overall survival was 95.1% at 3 years, 93.1% at 5 years, 91.2% at 7 years and 88.6% at 10 years. CONCLUSIONS: ARR and VSRR can be performed with low mortality and morbidity as well as a low rate of reintervention during the period of long-term follow-up, if performed by an experienced team with a consistent perioperative approach. This series provides contemporary evidence to balance the risks of aortic aneurysms and their rupture at diameters of <5.5 cm against the risks and benefits of surgery.

Improving sleep at altitude: a comparison of therapies.

OBJECTIVE: This study aimed to compare 3 treatment modalities during sleep at an altitude of 5300 m to identify strategies for reducing the incidence of periodic breathing at high altitude. METHODS: Fifteen trekkers, with identical ascent profiles and no signs or symptoms of altitude illness, served as subjects. All study participants arrived at 5300 m after a gradual ascent from 1300 m. On their second night at 5300 m, subjects were randomly assigned (with a computer-based random assignment procedure) to 1 of 4 different treatment groups: control (n = 4); 1 L/min O(2) via a demand system during sleep (n = 3); 1 L/min O(2)/CO(2) mix (1.5% CO(2)) via a demand system during sleep (n = 4); or 125 mg acetazolamide 30 minutes before bedtime (n = 4). Heart rate, respiration rate, blood oxygen saturation, tidal volume, minute volume, and apnea hypopnea index were measured. RESULTS: Upon comparing the 4 groups, there were no statistically significant differences between the variables. One-way analysis of variance indicated a trend toward statistical significance for SaO(2) between groups (F = 2.9, P = .08), and Tukey Honestly Significant Difference (HSD) post hoc tests indicated a trend in the SaO(2) difference between the 1 L/min oxygen and control groups (P = .07). While 1-way analysis of variance suggested no difference for respiratory rate between groups (F = 2.5, P = .1), Tukey HSD indicated a trend in statistical difference of the respiratory rate between 1 L/min O(2) and 1 L/min O(2)/CO(2) mixture (P = .08). CONCLUSIONS: These statistical trends found between control and treatment groups indicate that further study is warranted.

Relationship between indexed aortic area and aortic diameter in bicuspid aortic valve aortopathy: A retrospective cohort study.

BACKGROUND: Aortic dissection is a life-threatening complication of bicuspid aortic valve (BAV)-associated aortopathy. In these populations, whilst prophylactic replacement of proximal thoracic aortic aneurysms (TAAs) is generally recommended at threshold diameters ≥5.5 cm, dissection may occur in smaller aortas. An alternative size-based parameter, the cross-sectional aortic area/patient height ratio (indexed aortic area, IAA), correlates with increased dissection risk at abnormal values > 10 cm2/m. We sought to assess the utility of the IAA in identifying at-risk BAV-associated TAAs with abnormal IAA, albeit with sub-threshold aortic diameter. MATERIALS AND METHODS: We retrospectively identified 69 patients with BAV-associated TAAs who underwent surgical repair between 2010 and 2016. Aortic diameter was measured on pre-operative imaging, and IAA calculated, at the mid-sinus of Valsalva, sino-tubular junction and mid-ascending aorta for each patient. We determined proportions of aneurysms with IAA >10 cm2/m, median IAAs corresponding to aortic diameters <4.0 cm, 4.0-4.5 cm, 4.5-5.0 cm, 5.0-5.5 cm and >5.5 cm, and median aortic diameters corresponding to an abnormal IAA. RESULTS: 50.9%, 12.5% and 64.6% of aneurysms at the sinus of Valsalva, sino-tubular junction and mid-ascending aorta, respectively, had an abnormal IAA. 51.9% and 88.9% of patients with aortic diameter 4.5-5.0 cm and 5.0-5.5 cm, respectively, had an abnormal IAA. In aneurysms with abnormal IAA involving the sinus of Valsalva, sino-tubular junction, and mid-ascending aorta, median aortic diameters were 4.98 cm, 5.04 cm and 5.11 cm, respectively. Overall, 57/72 (79.2%) at-risk aneurysms with IAA >10 cm2/m had diameters smaller than the 5.5 cm guideline cut-off for surgical intervention. CONCLUSION: Significant proportions of BAV-associated TAAs are at increased risk of aortic dissection attending an IAA >10 cm2/m, whilst not fulfilling the size criteria indicating aortic surgery in contemporary guidelines. Further analysis of IAA in larger BAV cohorts is necessary to clarify its role in patient selection and optimal timing for prophylactic aortic replacement.

Effect of losartan on performance and physiological responses to exercise at high altitude (5035 m).

OBJECTIVE: Altitude-related and exercise-related elevations in blood pressure (BP) increase the likelihood of developing pulmonary hypertension and high-altitude illness during high-altitude sojourn. This study examined the antihypertensive effect and potential exercise benefit of the angiotensin II receptor antagonist losartan when taken at altitude. METHODS: Twenty participants, paired for age and ACE genotype status, completed a double-blinded, randomised study, where participants took either losartan (100 mg/day) or placebo for 21 days prior to arrival at 5035 m (Whymper Hut, Mt Chimborazo, Ecuador). Participants completed a maximal exercise test on a supine cycle ergometer at sea level (4 weeks prior) and within 48 hours of arrival to 5035 m (10-day ascent). Power output, beat-to-beat BP, oxygen saturation (SpO2) and heart rate (HR) were recorded during exercise, with resting BP collected from daily medicals during ascent. Before and immediately following exercise at 5035 m, extravascular lung water prevalence was assessed with ultrasound (quantified via B-line count). RESULTS: At altitude, peak power was reduced relative to sea level (p<0.01) in both groups (losartan vs placebo: down 100±29 vs 91±28 W, p=0.55), while SpO2 (70±6 vs 70±5%, p=0.96) and HR (146±21 vs 149±24 bpm, p=0.78) were similar between groups at peak power, as was the increase in systolic BP from rest to peak power (up 80±37 vs 69±33 mm Hg, p=0.56). Exercise increased B-line count (p<0.05), but not differently between groups (up 5±5 vs 8±10, p=0.44). CONCLUSION: Losartan had no observable effect on resting or exercising BP, exercise-induced symptomology of pulmonary hypertension or performance at 5035 m.

Does the Aortic Annulus Dilate After Aortic Root Remodeling?

BACKGROUND: The 2 main techniques of valve-sparing aortic root replacement (VSRR) are remodeling and reimplantation. There is concern that the aortic annulus, which is not stabilized in remodeling technique, may dilate over time and cause aortic regurgitation. Our aim was to assess whether the aortic annulus dilates after VSRR with remodeling technique without aortic annuloplasty. METHODS: Data on patients undergoing elective or urgent VSRR remodeling technique between 2005 and 2018 were collected. Patients undergoing arch and emergency surgery for acute type A aortic dissection were excluded. Preoperative aortic annulus diameter was measured by transthoracic echocardiography, and this was compared with the annulus diameter measured from the most recently available transthoracic echocardiography. The requirement for reintervention during follow-up was recorded. RESULTS: Between 2005 and 2018, 98 patients underwent VSRR. Sixty-six (67.3%) had Marfan syndrome or Loeys-Dietz syndrome. Median age was 60 (interquartile range, 18-68) years and 71 (72.4%) were men. Median cross-clamp and cardiopulmonary bypass times were 122 (interquartile range, 104-164) minutes and 138 (interquartile range, 121-198) minutes, respectively. Median intensive care unit and hospital stay were 1 day and 6 days, respectively. No patients suffered perioperative stroke. There was no in-hospital mortality. At median follow-up of 7.1 years (interquartile range, 5-129 months), mean postoperative annular diameter was 25.7 mm, from 24.2 mm preoperatively (P = .403). One patient required aortic valve replacement during follow-up. Freedom from moderate or severe aortic regurgitation was 97%. CONCLUSIONS: There was no significant aortic annular dilatation in selected patients undergoing remodeling VSRR. Our data do not support routine use of annuloplasty in patients with annular diameter less than or equal to 25 mm.

Understanding decision making about major surgery: protocol for a qualitative study of shared decision making by high-risk patients and their clinical teams.

INTRODUCTION: Surgical treatments are being offered to more patients than ever before, and increasingly to high-risk patients (typically multimorbid and over 75). Shared decision making is seen as essential practice. However, little is currently known about what 'good' shared decision making involves nor how it applies in the context of surgery for high-risk patients. This new study aims to identify how high-risk patients, their families and clinical teams negotiate decision making for major surgery. METHODS AND ANALYSIS: Focusing on major joint replacement, colorectal and cardiac surgery, we use qualitative methods to explore how patients, their families and clinicians negotiate decision making (including interactional, communicative and informational aspects and the extent to which these are perceived as shared) and reflect back on the decisions they made. Phase 1 involves video recording 15 decision making encounters about major surgery between patients, their carers/families and clinicians; followed by up to 90 interviews (with the same patient, carer and clinician participants) immediately after a decision has been made and again 3-6 months later. Phase 2 involves focus groups with a wider group of (up to 90) patients and (up to 30) clinicians to test out emerging findings and inform development of shared decision making scenarios (3-5 summary descriptions of how decisions are made). ETHICS AND DISSEMINATION: The study forms the first part in a 6-year programme of research, Optimising Shared decision-makIng for high-RIsk major Surgery (OSIRIS). Ethical challenges around involving patients at a challenging time in their lives will be overseen by the programme steering committee, which includes strong patient representation and a lay chair. In addition to academic outputs, we will produce a typology of decision making scenarios for major surgery to feed back to patients, professionals and service providers and inform subsequent work in the OSIRIS programme.

Hypoxia is not the primary mechanism contributing to exercise-induced proteinuria.

INTRODUCTION: Proteinuria increases at altitude and with exercise, potentially as a result of hypoxia. Using urinary alpha-1 acid glycoprotein (α1-AGP) levels as a sensitive marker of proteinuria, we examined the impact of relative hypoxia due to high altitude and blood pressure-lowering medication on post-exercise proteinuria. METHODS: Twenty individuals were pair-matched for sex, age and ACE genotype. They completed maximal exercise tests once at sea level and twice at altitude (5035 m). Losartan (100 mg/day; angiotensin-receptor blocker) and placebo were randomly assigned within each pair 21 days before ascent. The first altitude exercise test was completed within 24-48 hours of arrival (each pair within ~1 hour). Acetazolamide (125 mg two times per day) was administrated immediately after this test for 48 hours until the second altitude exercise test. RESULTS: With placebo, post-exercise α1-AGP levels were similar at sea level and altitude. Odds ratio (OR) for increased resting α1-AGP at altitude versus sea level was greater without losartan (2.16 times greater). At altitude, OR for reduced post-exercise α1-AGP (58% lower) was higher with losartan than placebo (2.25 times greater, p=0.059) despite similar pulse oximetry (SpO2) (p=0.95) between groups. Acetazolamide reduced post-exercise proteinuria by approximately threefold (9.3±9.7 vs 3.6±6.0 µg/min; p=0.025) although changes were not correlated (r=-0.10) with significant improvements in SpO2 (69.1%±4.5% vs 75.8%±3.8%; p=0.001). DISCUSSION: Profound systemic hypoxia imposed by altitude does not result in greater post-exercise proteinuria than sea level. Losartan and acetazolamide may attenuate post-exercise proteinuria, however further research is warranted.

A diver's guide to subaquatic envenomation in the Mediterranean.

INTRODUCTION: Between 40,000 and 50,000 divers and swimmers are envenomated each year and diving as a hobby is becoming increasingly popular. In the Mediterranean, envenomation is most often by Weever fish, Scorpion fish and jellyfish but coral and sea urchins may also be venomous. ENVENOMATION: Most stings cause local inflammation, oedema and pain. The severity of pain varies with the venom and the amount injected. In severe cases, stings may be life-threatening due to cardiogenic or anaphylactic shock or penetration of vital structures. MANAGEMENT: Most cases of envenomation are preventable with a combination of measures including the avoidance of contact through good buoyancy control, the wearing of body-suits, and by maintaining visual awareness. Immediate management is to return to the surface, elevate and wash the site of injury. Immersion in hot water followed by simple analgesics for pain relief has been shown to be more effective than other methods. More severe cases should be identified by symptoms including confusion and heavy bleeding and referred to qualified medical care. CONCLUSION: Envenomation by subaquatic species is common and preventable yet the dissemination of the appropriate knowledge is limited. This knowledge summary provides pertinent information aimed at divers in preventing and managing such injuries.

Changes in pupil dynamics at high altitude--an observational study using a handheld pupillometer.

Gross pupil dynamics are used as an indirect measure of brain function. Changes in hypoxia and intracranial pressure are thought to alter pupil responses to light. This study assessed a portable handheld pupil measuring device (pupillometer) in the field investigating the changes in pupil size, speed of reaction, and rate of constriction/dilatation with hypoxia induced by changes in altitude. A correlation between pupil dynamics and acute mountain sickness was sought. Seventeen volunteers were studied following acute exposure to 3450 m and then during a trek to 4770 m in Ladakh, India. The pupillometer was used to record maximum and minimum pupil diameter in response to a standard light source with calculation of latency, constriction and dilatation velocities. Acute mountain sickness (AMS) was recorded using Lake Louise self completed questionnaires both in the morning and afternoon on each day. Acute altitude exposure resulted in a significant reduction of percentage change in pupil size (36.5% to 24.1% p=<0.001), significant delay in pupillary contraction (latency; 0.208 to 0.223 seconds p=0.015) and a significant slowing of the rate of contraction (constriction velocity; -2.77 mm/s to -1.75 mm/s p=0.012). These changes reverted to normal during a period of acclimatization. A significant diurnal variation in pupil size was also observed. There was no significant difference between subjects with and without AMS. The handheld pupillometer is a suitable robust tool for monitoring changes in pupil dynamics in the field. With acute exposure to hypobaric hypoxia associated with an ascent to a moderate altitude, there is a general slowing of pupil function which reverts to normal within a few days of acclimatization. There appears to be a marked diurnal variation in pupil size. The measurements clearly demonstrated an effect of hypoxia on cerebral function, but these changes did not relate to moderate AMS.

The influence of prolonged intensive care stay on quality of life, recovery, and clinical outcomes following cardiac surgery: A prospective cohort study.

OBJECTIVE: To examine the influence of prolonged intensive care unit (ICU) stay on quality of life and recovery following cardiac surgery. METHODS: Quality of life was assessed using the Short Form 36 Health Survey (SF36). The Postoperative Quality of Recovery Scale was used to assess quality of recovery, disability, and cognition after ICU discharge over 12 months' follow-up. Prolonged ICU stay was defined as ≥3 postoperative days. Mortality and major adverse cardiac and cerebrovascular events were recorded up to 12 months. RESULTS: For quality of life, the physical component improved over time in both groups (P < .01 for both groups), as did the mental component (P < .01 for both groups). The long ICU group had lower physical and mental components over time (both P values < .01), but by 12 months the values were similar. The overall quality of recovery was lower for the long ICU group (P < .01). Likewise, we found higher rates of recovery in the normal ICU group than in the long ICU group in terms of emotive recovery (P < .01), activities of daily living (P < .01), and cognitive recovery (P = .03) but no differences in terms of physiologic (P = .91), nociceptive (P = .89), and satisfaction with anesthetic care (P = .91). Major adverse cardiac and cerebrovascular events (P < .01), 30-day mortality (P < .01), and length of ward stay (P < .01) were all higher with prolonged ICU stay. CONCLUSIONS: Patients with prolonged ICU stay have lower quality of life scores; however, they achieve similar midterm quality of recovery, but with reduced survival, increased major adverse cardiac and cerebrovascular events, and longer hospital length of stay.

Analysis of aortic area/height ratio in patients with thoracic aortic aneurysm and Type A dissection.

OBJECTIVES: Significant proportions of aortic dissections occur at aortic diameters <5.5 cm. By indexing aortic area to height and correlating with absolute aortic diameter, we sought to identify those aneurysm patients with aortic diameters <5.5 cm who do not meet current size thresholds for surgery, yet with corresponding abnormal indexed aortic areas (IAAs) >10 cm2/m, are at increased risk of aortic complications. METHODS: IAAs were calculated at 3 aortic locations in 187 aneurysm and 66 dissection patients operated on between 2010 and 2016 at our tertiary aortic centre. Proportions of patients with IAA >10 cm2/m, mean IAAs corresponding to aortic diameters <4.0 cm, 4.0-4.5 cm, 4.5-5.0 cm, 5.0-5.5 cm and >5.5 cm, and mean aortic diameters corresponding to IAAs 10-12 cm2/m, 12-14 cm2/m and >14 cm2/m were determined. RESULTS: Proportions of patients with abnormal IAAs were similar in both groups. In all, 49.1% of aneurysm patients with aortic diameters 4.5-5.0 cm, and 98.5% with aortic diameters 5.0-5.5 cm had abnormal IAAs. Out of 200 separate aneurysms with IAAs >10 cm2/m between the mid-sinus and mid-ascending aorta, 139 (69.5%) would not warrant surgery according to existing guidelines. CONCLUSIONS: Using the IAA, we identified a significant proportion of patients with thoracic aortic aneurysms who are at increased risk of aortic complications, despite current aortic guidelines not endorsing surgical intervention in this group. Our data suggests the IAA may be useful in preoperative risk evaluation and as a criterion for surgery.