Learning Curve for Flow Diversion of Posterior Circulation Aneurysms: A Long-Term International Multicenter Cohort Study

BACKGROUND AND PURPOSE

Flow diversion has gradually become a standard treatment for intracranial aneurysms of the anterior circulation. Recently, the off-label use of the flow diverters to treat posterior circulation aneurysms has also increased despite initial concerns of rupture and the suboptimal results. This study aimed to explore the change in complication rates and treatment outcomes across time for posterior circulation aneurysms treated using flow diversion and to further evaluate the mechanisms and variables that could potentially explain the change and outcomes.

MATERIALS AND METHODS

A retrospective review using a standardized data set at multiple international academic institutions was performed to identify patients with ruptured and unruptured posterior circulation aneurysms treated with flow diversion during a decade spanning January 2011 to January 2020. This period was then categorized into 4 intervals.

RESULTS

A total of 378 procedures were performed during the study period. Across time, there was an increasing tendency to treat more vertebral artery and fewer large vertebrobasilar aneurysms (P = .05). Moreover, interventionalists have been increasingly using fewer overlapping flow diverters per aneurysm (P = .07). There was a trend toward a decrease in the rate of thromboembolic complications from 15.8% in 2011-13 to 8.9% in 2018-19 (P = .34).

CONCLUSIONS

This multicenter experience revealed a trend toward treating fewer basilar aneurysms, smaller aneurysms, and increased usage of a single flow diverter, leading to a decrease in the rate of thromboembolic and hemorrhagic complications.

Intratympanic corticosteroid injection as a first-line treatment of the patients with idiopathic sudden sensorineural hearing loss compared to systemic steroid: A systematic review and meta-analysis

OBJECTIVES

The current study aimed to investigate if there is a difference in the use of intratympanic steroid therapy (IST), compared to systemic steroid treatment (SST), as an initial treatment for patients with sudden sensorineural hearing loss (SSNHL) by a meta-analysis design performed on the mean pure-tone average (PTA) improvement and the complete recovery rate.

METHODS

A systematic literature review was performed on randomized controlled trials published from 1990 to August 2020 in some databases including PubMed/MEDLINE, Scopus, Embase, Web of Science, Cochrane library/CENTRAL, Ovid, ProQuest, Google Scholar, and clinical trials.gov. The primary outcomes of interest were pure-tone average improvement and complete recovery rates.

RESULTS

Six eligible studies with 496 patients (250 patients in the IST group and 246 subjects in the SST group) were included in this study. The pooled standardized mean difference of the PTAs was estimated as 0.07 (95% CI = -0.10 to 0.25; I² = 0.0%, P = 0.668), and the pooled odds ratio of complete recovery rate was obtained as 1.00 (95% CI = 0.66 to 0.151; I² = 31.6, P = 0.199). Moreover, the pooled standardized mean difference of pure-tone average for the intratympanic steroid treatment group compared to the patients with oral steroid treatment was 0.07 (95% CI = -0.12 to 0.26; I² = 0.0%, P = 0.526).

CONCLUSIONS

The current study demonstrated that the effect of intratympanic injection of corticosteroid, as a first-line treatment, is not statistically different from the systemic route in improving the hearing outcomes among patients with SSNHL.

Robotic surgery of head and neck cancers, a narrative review

Head and neck cancers are the most common cancers in the body. Treatments are determined on the basis of the location and stage of the primary tumor. The goal of treatment is to eliminate the tumor, prevent recurrence or metastasis, and maintain the quality of life. There are several treatments available for the management of head and neck cancers, including surgery, radiation therapy, chemotherapy, new molecular agents, and a combination of them. Transoral robotic technique is a short-time operation using a type of robotic machine in which the patient undergoes anesthesia for a shorter time and the side effects of this operation and the time of hospitalization are less than open surgery. Due to the importance of speed and accuracy in head and neck cancer surgery and the importance of application of robotics in surgery, the present study was designed and implemented to review the application of robotics in the management of head and neck cancers. In this review study, the keywords: application, robotic, surgical, head cancer, transoral robotic surgery (TORS), and neck cancer, were searched in ISI, PubMed, Scopus, Google scholar databases. Related articles written domestically or abroad that have covered areas such as the background of transoral robotic surgery, maintaining organ function and approaches, the advantages and disadvantages of TORS, the affordability of TORS, the combination of TORS with other therapeutic approaches published from 2003 to 2019 were reviewed. The use of robotic surgery for precise operations such as head and neck cancers seems to be essential. More advanced robotic devices are expected to expand the surgery treatment for head and neck cancers as well as the results of using TORS for oncologic optimization and acceptability of results while maintaining organ function and patient's quality of life.

Impact of Acamprosate on Chronic Tinnitus: A Randomized-Controlled Trial

OBJECTIVES

Tinnitus is a common and distressing otologic symptom, with various probable pathophysiologic mechanisms, such as an imbalance between excitatory and inhibitory mechanisms. Acamprosate, generally used to treat alcoholism, is a glutaminergic antagonist and GABA agonist suggested for treating tinnitus. Thus, we aimed to evaluate the efficacy and safety of acamprosate in the treatment of tinnitus.

METHODS

The current randomized-controlled trial study included 20 subjects with chronic tinnitus. After performing psycho-acoustic, psychometric and electrophysiological evaluations, all studied tinnitus subjects were randomly divided into two groups of acamprosate and placebo. The first group received oral acamprosate (two tablets of 333 mg/d, three times a day), whereas the second group was given placebo treatment (two tablets, three times a day). After the first 30 days, all evaluations were repeated for the studied groups just in the same manner before the study. Subsequently, the final results of each evaluation were compared together with the baseline values.

RESULTS

Nine studied subjects randomly received acamprosate, whereas eleven others received a placebo. There was no significant improvement in the psycho-acoustic tests, except a decrease was observed in the pitch match of tinnitus (P = .039). For those subjects who were receiving acamprosate, a significant reduction was observed in tinnitus handicap inventory (P = .006), tinnitus questionnaire scores (P = .007), and the visual analog scores (P = .007) compared to the placebo group. There was a significant reduction in Action Potential latency (P = .048) as well as an increase in the amplitude of distortion product otoacoustic emissions at 4 kHz (P = .048).

CONCLUSIONS

The study results indicated a subjective relief of tinnitus as well as some degree of the electrophysiological improvement at the level of the cochlear and the distal portion of the auditory nerve among the subjects who received the acamprosate.

CLINICAL TRIAL REGISTRATION CODE

IRCT2013121115751N1.

Rapidly progressive fatal orbito-cerebral mucormycosis in an immunocompetent patient following entry of an insect into his eye; a case report and literature review

Mucormycosis, an uncommon and rapidly progressive fungal infection, is mainly seen in immunocompromised patients. However, immunocompetent individuals can also be infected. Here, we present a rapidly progressive orbito-cerebral mucormycosis in an immunocompetent patient, who had a history of entry of an insect into his eye. We report an immunocompetent patient, who had a history of entry of an insect into his eye, presented with left eye panophthalmitis, cellulitis and loss of vision. He underwent orbital exenteration. Then, mucormycosis was diagnosed and amphotericin B was initiated. Left cavernous sinus and internal carotid artery involvement were found in brain magnetic resonance imaging (MRI) and cerebrovascular accident (CVA) was diagnosed. Surgical debridement of necrotic tissue was performed, and postoperatively, our patient died following CVA. Mucormycosis, as a fatal fungal infection, requires early diagnosis, appropriate early surgical and rapid antifungal management so that successful outcome can be achieved.

Robotic surgery of head and neck cancers, a narrative review

Head and neck cancers are the most common cancers in the body. Treatments are determined on the basis of the location and stage of the primary tumor. The goal of treatment is to eliminate the tumor, prevent recurrence or metastasis, and maintain the quality of life. There are several treatments available for the management of head and neck cancers, including surgery, radiation therapy, chemotherapy, new molecular agents, and a combination of them. Transoral robotic technique is a short-time operation using a type of robotic machine in which the patient undergoes anesthesia for a shorter time and the side effects of this operation and the time of hospitalization are less than open surgery. Due to the importance of speed and accuracy in head and neck cancer surgery and the importance of application of robotics in surgery, the present study was designed and implemented to review the application of robotics in the management of head and neck cancers. In this review study, the keywords: application, robotic, surgical, head cancer, transoral robotic surgery (TORS), and neck cancer, were searched in ISI, PubMed, Scopus, Google scholar databases. Related articles written domestically or abroad that have covered areas such as the background of transoral robotic surgery, maintaining organ function and approaches, the advantages and disadvantages of TORS, the affordability of TORS, the combination of TORS with other therapeutic approaches published from 2003 to 2019 were reviewed. The use of robotic surgery for precise operations such as head and neck cancers seems to be essential. More advanced robotic devices are expected to expand the surgery treatment for head and neck cancers as well as the results of using TORS for oncologic optimization and acceptability of results while maintaining organ function and patient's quality of life.

Endothelialization following Flow Diversion for Intracranial Aneurysms: A Systematic Review

BACKGROUND

The underlying mechanism of action of flow diverters is believed to be the induction of aneurysm thrombosis and simultaneous endothelial cell growth along the device struts, thereby facilitating aneurysm exclusion from the circulation. Although extensive attention has been paid to the role of altered cerebrovascular hemodynamics using computational fluid dynamics analyses, relatively less emphasis has been placed on the role of the vascular endothelium in promoting aneurysm healing.

PURPOSE

Our aim was to systematically review all available literature investigating the mechanism of action of flow diverters in both human patients and preclinical models.

DATA SOURCES

A systematic search of PubMed, Cochrane Central Register of Controlled Trials MEDLINE, EMBASE, and the Web of Science electronic data bases was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

STUDY SELECTION

We selected articles assessing the role of endothelialization in flow-diverter treatment of cerebral aneurysms, including both preclinical and clinical studies.

DATA ANALYSIS

Ten articles were eligible for inclusion in this review. Two assessed endothelialization in human patients, while the other 8 used preclinical models (either rabbits or pigs).

DATA SYNTHESIS

Methods used to assess endothelialization included optical coherence tomography and scanning electron microscopy.

LIMITATIONS

A limitation was the heterogeneity of studies.

CONCLUSIONS

Current data regarding the temporal relationship to flow-diverter placement has largely been derived from work in preclinical animal models. Whether these cells along the device struts originate from adjacent endothelial cells or are the result of homing of circulating endothelial progenitor cells is equivocal.

Chondroradionecrosis of the Larynx in a Patient with Laryngeal: A Case Report

INTRODUCTION

Actinomycosis of the larynx has been rarely reported in the literature and usually occurs in patients with a history of laryngeal carcinoma and radiation therapy. However, its co-existence with chondroradionecrosis due to radiotherapy is even rarer. The most common site of infection is the cervicofacial region, especially in the submandibular area.

CASE REPORT

Here we report a 63-year-old male with a history of chemoradiotherapy because of laryngeal cancer 1 year earlier who presented with laryngeal actinomycosis. After prolonged penicillin-based treatment, the patient underwent thyroid cartilage defect reconstructive surgery because of a laryngocutaneous fistula due to chondroradionecrosis. The diagnosis, work-up, and management of the case are discussed, as well as a review of the literature.

CONCLUSION

Although actinomycotic infection of the larynx is rare, it should be considered in the differential diagnosis of laryngeal complaints, especially in immunocompromised patients.

Vitamin D Levels in Children with Adenotonsillar Hypertrophy and Otitis Media with Effusion

INTRODUCTION

Vitamin D has been suggested to play a considerable role in the function of the immune system in various infectious, inflammatory, and autoimmune conditions. Otitis media with effusion (OME), defined as the presence of non-purulent fluid within the middle ear without signs or symptoms of suppurative otitis media, has a number of inflammatory predisposing factors. This study was designed to explore the association between vitamin D deficiency and OME.

MATERIALS AND METHODS

In this cross-sectional study, 74 children aged 2-7 years with an obstructive indication for adenotonsillectomy were included. Patients were divided into two groups based on the need for ventilation tube insertion for OME. Thirty-two children were enrolled in the OME group and 42 in the control group. The mean vitamin D level was compared between the two groups.

RESULTS

Mean vitamin D concentration in all patients was 11.96±5.85 ng/ml (9.79±4.36 ng/ml in the OME group and 13.61±6.33 ng/ml in the control group; P=0.003). There was also a significant difference in levels of vitamin D in patients referred in winter (9.0±2.94 ng/ml) compared with the summer (19.85±4.21 ng/ml; P=0.001). Data analyzed based on the season in which the patients were referred showed no significant difference between the OME and the control group.

CONCLUSION

Although our results showed lower serum levels of vitamin D in OME patients, the difference was not significant when seasons were taken into consideration. Therefore, the season is an important confounding factor in any research related to vitamin D due to the effect of sun-induced vitamin D.

A Comparison Between Two Methods of Face-Lift Surgery in Nine Cadavers: SMAS (Superficial Musculo-Aponeurotic System) Versus MACS (Minimal Access Cranial Suspension)

BACKGROUND

This study aimed to compare the average amounts of facial skin and muscle lifting in two different face-lift methods, superficial musculo-aponeurotic system (SMAS) plication and minimal access cranial suspension (MACS), to evaluate the effectiveness of each method in facial excursion.

METHODS

Thirty-six face-lift surgeries were performed on nine cadavers between October and December 2010. Both SMAS and MACS surgeries were done on each side of the cadaver faces. The average amounts of skin and muscle lifting up and out in three defined anatomical landmarks were compared between the two methods, SMAS plication and MACS lift procedure.

RESULTS

Nine fresh cadavers with the mean age of 53 ± 6.7 years entered the study. Seven (77.8 %) were males and two (22.2 %) were females. The average amounts of lifting of the anatomical landmarks up and out were significantly greater in the SMAS plication method compared to the MACS lift procedure (P values <0.05), whereas facial symmetry was not significantly different between the two methods.

CONCLUSION

The overall amounts of facial skin and muscle lifting by the SMAS plication method were greater than the MACS lift procedure. However, it does not justify ignoring the benefits of the MACS lift procedure in terms of less invasiveness and quicker recovery.

NO LEVEL EVIDENCE

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Investigation of the potential utility of a linomide analogue for treatment of choroidal neovascularization

The aim of this study was to test the selectivity, in-vivo effectiveness, and potential mechanism of action of a linomide analogue (N-phenyl-1,2-dihydro-4-hydroxyl-2-oxo-quinoline-3-carboxamide, Lin05) for inhibition of choroidal neovascularization. The selectivity of Lin05 was tested in cell proliferation assays with human umbilical vein endothelial cells (HUVEC) and a retinal pigmented epithelial cell line(ARPE-19). In-vivo anti-angiogenic effect of Lin05 was investigated utilizing an experimental laser-induced choroidal neovascularization (ECNV) model in adult Brown Norway rats. Western blot and/or reverse transcriptase-PCR was used to test the effect of Lin05 on potential targets. Our results indicate that Lin05 is at least an 8-fold more selective inhibitor of endothelial cell proliferation compared to RPE cells. Systemic administration of Lin05 in an ECNV model was associated with a significant decrease in both vascular leakage on fluorescein angiography and lesion size by histopathology (p = 0.02). No systemic toxicity was detected for Lin05 in major organs such as the liver, lung and kidneys. Lin05 did not inhibit VEGF-induced VEGFR2 (KDR) phosphorylation in HUVEC nor was associated with decreased VEGF gene expression. Also it did not inhibit insulin-like growth factor (IGF-1) and Epidermal Growth Factor (EGF) induced activation of p42/p44 MAPK activation. It inhibited both PDGF- and bFGF-induced p42/p44 MAPK phosphorylation. However, the effect on PDGF was variable in different HUVEC cells. In conclusion, Lin05 is a potential anti-angiogenic agent for the treatment of eye diseases associated with pathological neovascularization. The anti-angiogenic effect of Lin05 is likely through inhibition of bFGF but not through inhibition of the VEGF/KDR pathway.

Management of symptomatic cholelithiasis in pregnancy

BACKGROUND

Symptomatic cholelithiasis occurs in pregnancy in our patient population, some of whom are diabetic. But its management remains controversial. How common is the problem? Is our current policy of management appropriate for our patients?

PATIENTS AND METHODS

The management of 162 pregnant patients admitted over a ten-year period with symptomatic cholelithiasis was evaluated in a retrospective study. The patients were divided into two groups: Group A, 58 patients with diabetes mellitus, and Group B, 104 nondiabetic patients.

RESULTS

Symptomatic cholelithiasis occurred in only 0.3% of our pregnant patients. Of 162 patients, 148 (91.4%) had successful conservative (nonsurgical) management. There was no fetal loss, premature birth, maternal morbidity or mortality. Fourteen patients who had failure of conservative treatment had surgical management. When the postpartum cholecystectomy hospitalization days were added to the total days of admission for the nonoperative cases, there was a significant difference in the mean total number of days of hospitalizations between the surgical cases, 12.4 days, and the nonsurgical cases, 20.5 days (P<0.001), but not in the mean number of hospitalizations, 2.3 versus 3.3.

CONCLUSION

Our current policy of conservative management seems optimal. It has, however, been achieved at the price per patient of 8 extra days of hospitalization. In keeping with recent improvements in surgery and the advent of laparoscopic surgery, a more cost-efficient approach would suggest a more aggressive policy.

Predictors of left ventricular outflow obstruction following single-stage repair of interrupted aortic arch and ventricular septal defect

This study looked at echocardiographic predictors of left ventricular outflow obstruction after primary neonatal repair of interrupted aortic arch and ventricular septal defect. Results of this study indicate that the only significant independent predictor of left ventricular outflow obstruction is aortic valve diameter; all patients with an aortic valve diameter <4.5 mm (Z score <-5) subsequently developed obstruction, whereas patients with annuli >4.5 mm (Z score >-5) remained free from obstruction.

Treatment of hypertension in the hemodialysis patient: beneficial or not?

Hypertension is common in the hemodialysis population. Although hypertension in the general population has been shown to reduce survival and to accelerate atherosclerosis, leading to serious cardiac and cerebrovascular morbidity, its effects are less clear in those undergoing dialysis. This review focuses on recent studies showing a favorable outcome in hypertensive hemodialysis patients when compared with those with lower blood pressure. The possible explanations for this paradoxic relationship are examined, and practical suggestions are given for the management of hypertension in the patient undergoing hemodialysis. We also present information on the morbiditiy associated with hypertension in the hemodialysis population.

Atrial natriuretic factor in oliguric acute renal failure. Anaritide Acute Renal Failure Study Group

Atrial natriuretic peptide (ANP), an endogenous hormone synthesized by the cardiac atria, has been shown to improve renal function in multiple animal models of acute renal failure. In a recent multicenter clinical trial of 504 patients with acute tubular necrosis (oliguric and nonoliguric), ANP decreased the need for dialysis only in the oliguric patients. In the present study, 222 patients with oliguric acute renal failure were enrolled into a multicenter, randomized, double-blind, placebo-controlled trial designed to assess prospectively the safety and efficacy of ANP compared with placebo. Subjects were randomized to treatment with a 24-hour infusion of ANP (anaritide, 0.2 microgram/kg/min; synthetic form of human ANP) or placebo. Dialysis and mortality status were followed up for 60 days. The primary efficacy end point was dialysis-free survival through day 21. Dialysis-free survival rates were 21% in the ANP group and 15% in the placebo group (P = 0.22). By day 14 of the study, 64% and 77% of the ANP and placebo groups had undergone dialysis, respectively (P = 0.054), and 9 additional patients (7 patients, ANP group; 2 patients, placebo group) needed dialysis but did not receive it. Although a trend was present, there was no statistically significant beneficial effect of ANP in dialysis-free survival or reduction in dialysis in these subjects with oliguric acute renal failure. Mortality rates through day 60 were 60% versus 56% in the ANP and placebo groups, respectively (P = 0.541). One hundred two of 108 (95%) versus 63 of 114 (55%) patients in the ANP and placebo groups had systolic blood pressures less than 90 mm Hg during the study-drug infusion (P < 0.001). The maximal absolute decrease in systolic blood pressure was significantly greater in the anaritide group than placebo group (33.6 versus 23.9 mm Hg; P < 0.001). This well-characterized population with oliguric acute renal failure had an overall high morbidity and mortality.

[The complications of wound healing after an operation for ventral hernia and their prevention]

For abdominal hernia 982 patients were operated. The complications had occurred in 18.6% of patients due to chronic inflammation and the presence of "sleeping" infection in the hiatal gates margins. Application of the elaborated prophylaxis complex of measures had permitted to lower the frequency of the wound healing complications down to 9%.

Hypertension in the haemodialysis population: any relationship to 2-years survival?

BACKGROUND

Few studies have quantified the effect of hypertension on survival in the haemodialysis (HD) population. We have previously reported lack of adverse effect of hypertension on 1-year mortality in a cohort of 649 haemodialysis patients (Am J Kidney Dis 1996; 28: 737-744). We report here the effect of hypertension on 2-year survival in the same cohort of patients.

METHODS

We reviewed the complete computerized files on 649 HD patients enrolled in 10 haemodialysis centres in the state of Mississippi, USA. One-month dialysis records for each patient from mid-October 1994 to mid-November 1994 were reviewed. Predialysis mean arterial pressure was calculated as immediate predialysis diastolic pressure plus one-third the difference between systolic and diastolic pressure. Patients were classified as hypertensive if their average pre-MAP was more than 114 mmHg or they were receiving antihypertensive drugs during the study period. Normotensives had a pre-MAP < 114 and were not receiving any antihypertensives. We followed these patients for 2 years to determine their survival and the effect of their BP status, as determined in October 1994, on 2-year mortality.

RESULTS

In univariate analysis, hypertension was associated with improved 2-years survival (relative risk 0.64, P=0.08 compared to normotensives). Furthermore, among the hypertensives, good blood pressure control (less than 140/90) was associated with increased relative risk of death at 2 years (RR 1.86, P=0.004). In multivariate analysis, taking age, race, serum albumin, and diabetic status into consideration, there was a 27% reduction in mortality among hypertensives compared to normtensives (RR 0.73, P=0.06). Other factors of significance in multivariate analysis were age (RR 1.03/year, P=0.02), serum albumin (RR 0.36/g, P<0.0001), diabetes mellitus (RR 1.35, P=0.07), and race (RR 0.64, P=0.05).

CONCLUSIONS

Our study suggests that hypertension has no adverse effect on survival at 2 years in the haemodialysis population.

Comparison of laparoscopic and open cholecystectomy at Prince Abdulrahman Al Sudairy Hospital, Saudi Arabia

The initial 300 patients whose symptomatic cholelithiasis was managed by laparoscopic cholecystectomy (LC) were matched to and compared with 300 patients managed by open cholecystectomy (OC) during the 30 months prior to the introduction of LC. Of the 300 LC attempted 292 (97.3%) were successful with conversion to OC rate of 2.7%. Besides the obviously better cosmetic results, LC patients had less post operative pain, mean doses of opiates needed 0.01 versus 5 for OC (p < 0.0001), were discharged earlier from the hospital, mean 3.1 days versus 8 days for OC (p < 0.001) and had less postoperative complications 4% versus 11% for OC. We conclude that not only is LC a better operation than OC, but also that in the regional referral centres such as ours, LC can safely supplant OC as the preferred modality for the management of symptomatic cholelithiasis.

Hyperparathyroidism in the hemodialysis population: a survey of 612 patients

There are no epidemiologic studies documenting the prevalence of hyperparathyroidism in the US hemodialysis population. We looked at a random sample of 612 hemodialysis patients enrolled in 10 outpatient dialysis units in Mississippi. Fifty percent of the patients surveyed had an intact serum parathyroid hormone (PTH) level more than three times normal (mean, 622 pg/mL). Another 25% had a less than normal PTH level (mean, 33 pg/mL), suggesting adynamic bone disease. Abnormal serum calcium was also common. Seventeen percent of patients were hypocalcemic and 14% were hypercalcemic. These high point prevalences occurred despite widespread use of calcium supplements and/or vitamin D (used in 90% of the patients surveyed). Black patients tended to have a lower serum calcium and higher PTH level than white patients. We also found that diabetic patients are less likely to have an elevated PTH level than nondiabetic patients. Elevated serum phosphorus was the most important factor correlating with the development of secondary hyperparathyroidism. Causes of inadequate control of hyperparathyroidism in this population require further study.

Acidosis and coma after hemodialysis

Ethylene glycol poisoning is a rare yet potentially fatal illness seen most commonly in association with ingestion by alcoholics or in suicide attempts. It is characterized by an elevated anion gap metabolic acidosis, osmolal gap, calcium oxalate crystals in the urine, and a well-defined clinical picture. Prompt treatment is crucial because effective intervention can prevent the neurologic, cardiac, pulmonary, and renal sequelae associated with ethylene glycol poisoning. Hemodialysis offers rapid clearance of ethylene glycol and its toxic metabolites. In this article, the case of a hemodialysis patient who suffered contamination of the dialysate solution with ethylene glycol, leading to altered mental status, coma, and severe anion gap metabolic acidosis, is reported. Despite prolonged dialysis and correction of the acidosis, the patient remained comatose and subsequently died.

Effects of one year of hemodialysis on weight and blood pressure in 434 patients

Excess volume is thought to be the major mechanism leading to hypertension in the hemodialysis population. Blood pressure measurements and volume parameters were obtained in 434 hemodialysis patients in 1994 and compared to their 1993 data. Equal numbers of patients were receiving antihypertensive treatment in both 1993 and 1994. The predialysis mean arterial pressure (pre-MAP) did not significantly change after 1 year of dialysis. The lack of change in blood pressure was evident in those who either lost or maintained body weight. There was no correlation between changes in interdialytic weight and changes in pre-MAP over 1 year. Volume sensitivity (described as the percentage decrease in blood pressure immediately after dialysis) was not different in 1993 from 1994. We conclude that irrespective of weight changes, the average hemodialysis patient does not show a significant change in blood pressure (BP) after 1 year of dialysis. This lack of improvement was evident regardless of age, sex, race, dialysis duration, or etiology of end-stage renal disease.

Hypertension in the hemodialysis population: any relation to one-year survival?

Few studies have quantified the effect of hypertension on survival in the hemodialysis population. We report the effect of hypertension on 1-year survival in 649 hemodialysis patients (89% black). In univariate analysis, hypertension was associated with improved 1-year survival (relative risk [RR], 0.48; P = 0.002 compared with normotensive patients). This effect of hypertension was mostly caused by the associated antihypertensive treatment because untreated hypertensive patients had survival rates equal to normotensive patients (RR, 0.87; P = 0.70). On the other hand, treated hypertensive patients fared better than normotensive patients (RR, 0.41; P = 0.0006). This was also true in multivariate analysis, in which antihypertensive treatment was associated with reduced RR (RR, 0.55; P = 0.02) whereas the level of blood pressure per se was insignificant (RR, 0.99; P = 0.63 per 1 mm Hg increase in predialysis mean arterial pressure). Other factors of significance in multivariate analysis included age (RR, 1.03/y; P = 0.0004), serum albumin (RR, 0.38/g; P = 0.002), and diabetes mellitus (RR, 1.58; P = 0.06). Our study suggests that antihypertensive treatment has a favorable effect on survival in the hemodialysis population irrespective of the level of blood pressure control.

Hypertension in the hemodialysis population: a survey of 649 patients

Accurate information on prevalence and status of blood pressure control among US hemodialysis patients is lacking. We have surveyed the status of blood pressure control in 649 hemodialysis patients (89.8% black) from 10 dialysis units in Mississippi. Our results show a hypertension prevalence of 72% (hypertension defined as mean arterial pressure prior to dialysis session > or = 114 mm Hg). This mean arterial pressure did not differ among black patients compared with white patients (P = 0.51). The majority of hypertensive patients (80%) had elevation of both systolic and diastolic blood pressure. Isolated systolic hypertension was present in only 20% of hypertensive patients and was not different between black and white patients (P = 0.10). Three hundred eighty-one patients (58.7% of the total population and 81.5% of the hypertensive patients) were receiving antihypertensives. Age was the only significant factor that correlated with blood pressure: older patients (> 65 years) had lower blood pressure (P < 0.0001). Race, time on dialysis, etiology of end-stage renal disease, adequacy of dialysis, and several excess volume parameters had no influence on the blood pressure level. Treated hypertensive patients had a predialysis mean blood pressure only 3 mm Hg less than the untreated hypertensive patients. No differences were found among four classes of antihypertensives with regard to the degree of blood pressure control. Patients with hypertension requiring more than one antihypertensive did not achieve a lower blood pressure than the untreated patients. There was no correlation between use of antihypertensives and the magnitude of decrease in blood pressure after dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Potassium adaptation in hypothyroidism: changes in transport adenosinetriphosphatases

To evaluate whether hypothyroidism alters the adaptive responses of renal transport adenosine-triphosphatases (ATPases) to modifications in dietary K content, we examined the activities of Na-K pump and H-K pump in hypothyroid rats under basal conditions and after dietary K changes. Hypothyroidism led to a decline in Na-K pump activity in all three nephron segments examined [proximal convoluted tubule from 2,333 +/- 103 to 1,099 +/- 32, medullary thick ascending limb from 4,344 +/- 119 to 1,613 +/- 61, and cortical collecting tubule (CCT) from 1,133 +/- 45 to 640 +/- 38 pmol.mm-1 x h-1; all P < 0.01 vs. euthyroid] along with morphological changes manifest in a decrease in tubule diameter. K loading led to an increase in Na-K pump activity in the CCT of both euthyroid (from 1,133 +/- 45 to 2,269 +/- 74, pmol.mm-1 x h-1, P < 0.01) and hypothyroid (from 640 +/- 38 to 1,118 +/- 67 pmol.mm-1 x h-1, P < 0.01) animals. Furthermore, in euthyroid rats, 3 wk of K depletion led to a major increase in H-K pump activity in both the CCT (from 203 +/- 14 to 331 +/- 22 pmol.mm-1 x h-1, P < 0.01) and medullary collecting tubule (MCT, from 137 +/- 9 to 210 +/- 14 pmol.mm-1 x h-1, P < 0.01). Hypothyroidism was associated with a decline in H-K pump activity in the CCT and MCT (to 94 +/- 6 and 55 +/- 5 pmol.mm-1 x h-1, respectively; both P < 0.01 vs. euthyroid).(ABSTRACT TRUNCATED AT 250 WORDS)

Gaps in the anion gap

OBJECTIVE

To review limitations of the use of serum anion gap in clinical practice.

DATA SOURCES

Original reports and reviews.

STUDY SELECTION

Sources containing the most recent pertinent information.

DATA SYNTHESIS

Theoretical and practical limitations beset the use of serum anion gap. Awareness of these limitations reduces but does not eliminate wrong diagnoses based on the anion gaps.

CONCLUSIONS

Serum anion gap has a limited value in the differential diagnosis of acid-base disorders and can be misleading.

Extrarenal potassium tolerance in chronic renal failure: implications for the treatment of acute hyperkalemia

The role of extrarenal potassium homeostasis is well recognized as a major mechanism for the acute defense against the development of hyperkalemia. The purpose of this report is to examine whether or not the various mechanisms of extrarenal potassium regulation are intact in patients with end-stage renal disease (ESRD). The available data suggest that with the development of ESRD and the uremic syndrome there is impaired extrarenal potassium metabolism that is related to a defect in the Na,K-adenosine triphosphatase (ATPase). The responsiveness of uremic patients to the various effector systems that regulate extrarenal potassium handling is discussed. Insulin is well positioned to play an important role in the regulation of plasma potassium concentration in patients with impaired renal function. The role of basal insulin may be even more important than previously appreciated, since somatostatin infusion causes a much greater increase in the fasting plasma potassium in rats with renal failure than in controls. Furthermore, stimulation of endogenous insulin by oral glucose results in a greater intracellular translocation of potassium in uremic rats than in controls. Under at least two common physiologic circumstances, feeding and vigorous exercise, endogenous catecholamines might also act to defend against acute increments in extracellular potassium concentration. However, it is important to appreciate that the response to beta 2-adrenoreceptor-mediated internal potassium disposal is heterogeneous as judged by the variable responses to epinephrine infusion. Based on the evidence presented in this report, a regimen for the treatment of life-threatening hyperkalemia is outlined. Interpretation of the available data demonstrate that bicarbonate should not be relied on as the sole initial treatment for severe hyperkalemia, since the magnitude of the effect of bicarbonate on potassium is variable and may be delayed. The initial treatment for life-threatening hyperkalemia should always include insulin plus glucose, as the hypokalemic response to insulin is both prompt and predictable. Combined treatment with beta 2-agonists and insulin is also effective and may help prevent insulin-induced hypoglycemia.

Myocardial oxygen supply/demand relations during phenylephrine infusions in dogs

Experiments were performed on 14 fentanyl-pentobarbital-anesthetized dogs to assess changes in myocardial oxygen supply/demand relations during intravenous infusions of phenylephrine (2.8 micrograms.kg-1.min-1). Myocardial blood flow was measured with radioactive microspheres. Myocardial oxygen and lactate extraction were determined. Myocardial oxygen consumption was calculated with the Fick equation. In series 1, measurements were obtained during phenylephrine-induced pressor responses. In series 2, measurements were obtained with aortic pressure maintained constant with an extracorporeal reservoir during phenylephrine infusion, so that coronary vasomotor responses could be assessed in the absence of increases in ventricular afterload and perfusion pressure. In series 1, the phenylephrine-induced increase in mean aortic pressure (+42%) was accompanied by proportional (60%) increases in myocardial blood flow and myocardial oxygen consumption and with no change in the endocardium-to-epicardium flow ratio, oxygen extraction, coronary sinus oxygen tension and oxygen saturation, or myocardial lactate extraction. In series 2, phenylephrine infusion caused a transmurally uniform 15% decrease in myocardial blood flow combined with a 10% decrease in myocardial oxygen consumption. The coronary arteriovenous oxygen difference increased modestly (+5%), resulting in small decreases in coronary sinus oxygen tension and oxygen saturation, whereas lactate extraction was unaffected. The present findings suggest that phenylephrine has a direct vasoconstrictor effect in the coronary circulation that is weak and completely overridden by metabolic autoregulatory mechanisms in response to pressure-induced augmentations in cardiac workload. The authors conclude that the myocardium is not at risk when phenylephrine is used to treat hypotension in patients with adequate cardiac function and coronary vasodilator reserve.