Akram Khan

Epidemiology of Acute Kidney Injury in the Intensive Care Unit

The incidence of acute kidney injury (AKI) in the intensive care unit (ICU) has increased during the past decade due to increased acuity as well as increased recognition. Early epidemiology studies were confounded by erratic definitions of AKI until recent consensus guidelines (RIFLE and AKIN) standardized its definition. This paper discusses the incidence of AKI in the ICU with focuses on specific patient populations. The overall incidence of AKI in ICU patients ranges from 20% to 50% with lower incidence seen in elective surgical patients and higher incidence in sepsis patients. The incidence of contrast-induced AKI is less (11.5%–19% of all admissions) than seen in the ICU population at large. AKI represents a significant risk factor for mortality and can be associated with mortality greater than 50%.

Uvulopalatopharyngoplasty in the Management of Obstructive Sleep Apnea: The Mayo Clinic Experience

OBJECTIVE To assess the role of uvulopalatopharyngoplasty (UPPP) in the treatment of obstructive sleep apnea (OSA) using polysomnography (PSG) data within 6 months before and after surgery. PATIENTS AND METHODS We analyzed PSG and body mass index (BMI) data from patients with OSA who were 18 years or older and who underwent UPPP between January 1, 1988, and August 31, 2006. RESULTS Sixty-three patients (51 men [81.0%]; mean ± SD age, 42.1±13.9 years; mean ± SD BMI, 34.9±7.2) underwent PSG a mean ± SD of 50±47 days before and 88.5±34.0 days after UPPP. Surgical cure was defined as a postoperative apnea-hypopnea index (AHI) of 5 or less. Fifteen patients (24%) achieved a surgical cure. Twenty-one patients (33%) had a postoperative AHI of 10 or less, whereas 32 (51%) achieved a 50% or greater reduction in AHI and/or an AHI of 20 or less. No significant changes were noted in BMI before and 6 months after UPPP. Patients who attained an AHI of 5 or less were younger (mean ± SD age, 35.9±13.1 vs 44±13.7 years; P =.05), had lower BMIs (mean ± SD, 30.8±6.5 vs 34.6±6.6; P =.05), and had less severe OSA (mean ± SD AHI, 38.1±33.6 vs 69.6±32.8; P =.004). Of the 48 patients (76%) with a post-UPPP AHI greater than 5, 35 (56%) received continuous positive airway pressure, with a mean reduction in pressure of 1.4 cm H 2 O (95% confidence interval, -0.4 to -2.4 cm H 2 O). CONCLUSION Independent of changes in BMI, in our retrospective analysis, UPPP achieved an AHI of 5 or less in 24% and an AHI of 10 or less in 33% of patients with OSA who underwent PSG 6 months before and after surgery. In those with residual OSA who received continuous positive airway pressure, the required pressure setting decreased by 1.4 cm H 2 O.

Delirium in Critically Ill Patients

Delirium in the intensive care unit (ICU) is a common diagnosis, with an incidence ranging between 45% and 87%. Delirium represents a significant burden both to the patient and to the health care system, with a 3.2-fold increase in 6-month mortality and annual US health care costs up to

Blood Culture Isolates in Hemodialysis Vascular Catheter-Related Bacteremia

16 billion. In this review, the diagnosis, epidemiology, and risk factors for delirium in the ICU are discussed. The pathophysiology of delirium and evolving prevention and treatment modalities are outlined.

Assessment of obstructive sleep apnea in adults undergoing bariatric surgery in the longitudinal assessment of bariatric surgery-2 (LABS-2) study.

Hemodialysis requires reliable and recurrent access to the central circulation and arteriovenous fistulas or grafts are the preferred modes of vascular access. However, in many patients the use of external tunneled vascular catheters may be necessary. The major complication of tunneled catheters is infection. Understanding local epidemiologic patterns of dialysis catheter-related bacteremia may help in the management of these patients. To address this issue, we reviewed the 5-year microbiologic culture results from all bacteremic hemodialysis patients with tunneled catheters at our institution. During this period, there were 203 organisms isolated from 153 positive blood cultures. Gram-positive, Gram-negative, and fungal species represented 55.7%, 43.3%, and 1% of isolates, respectively. Positive blood cultures classified according to the presence of a single Gram-positive or single Gram-negative organism, single fungus, or polymicrobial organisms, accounted for 41.8%, 29.4%, 0.6% and 28.1% of infectious events. From 2000–2004, there was a numerical trend toward a decrease in Gram-positive infection (64.3% versus 34.8% respectively, P = 0.12) and a numerical trend toward an increase in Gram-negative and polymicrobial bacteremias (17.9 versus 21.7, P = 0.07 and 17.9 versus 43.5, P = 0.09, respectively). These data indicate that bacteremic events in hemodialysis patients with vascular catheters are commonly due to a single Gram-positive organism, but the incidence of Gram-negative and polymicrobial bacteremia may be increasing. If confirmed in a prospective trial, adjustment of empiric antibiotic regimens for suspected catheter-associated bacteremia may be indicated.

Resistant hypertension and obstructive sleep apnea.

STUDY OBJECTIVES Evaluate frequency of diagnostic testing for obstructive sleep apnea (OSA), prevalence of OSA, and factors independently associated with OSA status in adults undergoing bariatric surgery. DESIGN, SETTINGS AND INTERVENTIONS: Longitudinal Assessment of Bariatric Surgery-2 (LABS-2) is an observational cohort of 2,458 adults undergoing bariatric surgery at 10 U.S. hospitals. Within 30 days prior to surgery, researchers determined if participants had a diagnostic polysomnography (PSG) in the previous 12 months. When available, apnea-hypopnea index (AHI) was recorded. Based on medical records and participant report, research clinicians recorded OSA status and positive airway pressure (PAP) use. Participants completed the Berlin Questionnaire (BQ). Multivariable logistic regression was used to determine factors independently associated with AHI-confirmed OSA status. RESULTS 28.7% (n = 693) of participants had a PSG within 12 months before surgery. Of subjects with AHI available (n = 509), 80.7% (n = 411) had OSA (AHI ≥ 5); 83.0% (n = 341) reported PAP use. In participants without a known AHI (n = 1,949), 45.4% (n = 884) had self-reported OSA; 81.2% (n = 718) reported PAP use. Self-reported history of snoring and pauses in breathing (odds ratio [OR] = 10.0; 95%, confidence interval [CI] = 4.8-20.6), male sex (OR = 5.1; 95% CI = 1.7-15.3), older age (OR = 1.4; 95% CI = 1.2-1.6 per 5 years), and larger sagittal abdominal diameter (OR = 1.8; 95% CI = 1.2-2.5 per 5 cm) were independently associated with a greater odds of confirmed OSA. CONCLUSIONS Preoperative diagnostic testing for OSA was infrequent. Prevalence estimates of OSA differed greatly between those with and without a past-year AHI (81% vs. 46%, respectively). Most BQ responses did not differentiate OSA status, but endorsement of snoring and pauses in breathing was independently associated with presence of OSA.

Effect of Angiotensin Converting Enzyme Inhibitors and Angiotensin Receptor Blockers on Serum Potassium Levels and Renal Function in Ambulatory Outpatients: Risk Factors Analysis

Hypertension (HTN) is a modifiable, highly prevalent risk factor for cardiovascular morbidity and renal dysfunction worldwide. In the United States, HTN affects one in three adults, contributes to one out of every seven deaths and to nearly half of all cardiovascular disease-related deaths. HTN is considered resistant when the blood pressure remains above goal despite lifestyle modification and administration of three antihypertensive agents of different classes including a diuretic. Large population-based studies have suggested that obstructive sleep apnea (OSA) is a risk factor for resistant HTN. The mechanism proposed is a pattern of intermittent hypoxia associated with hyperaldosteronism, increased sympathetic tone, endothelial dysfunction, and inflammation. In this review we discuss the association between OSA and resistant HTN, the physiologic mechanisms linking OSA with resistant HTN, and the effect of continuous positive airway pressure therapy (CPAP) on blood pressure in patients with resistant HTN. While the reduction in blood pressure with CPAP is usually modest in patients with OSA, a decrease of only a few mmHg in blood pressure can significantly reduce cardiovascular risk. Patients presenting to a center specializing in management of hypertension should be screened and treated for OSA as a potentially modifiable risk factor.

Role of Obesity in Asthma Control, the Obesity-Asthma Phenotype

Background:Angiotensin II inhibition with angiotensin converting enzyme inhibitors (ACEinh) and angiotensin receptor blockers (ARB) has reno- and cardioprotective effects but can also cause acute renal insufficiency and/or hyperkalemia. Study Design:A retrospective analysis was performed in an ambulatory population, to define the incidence and risk factors for hyperkalemia in ACEinh/ARB naïve patients. Setting and Participants:Records of patients from 10 Oklahoma regional VA outpatient facilities, in whom ACEinh/ARB was initiated from January 2000 to May 2004, were reviewed. Diabetes mellitus, estimated glomerular filtration rate (eGFR), in mL/min/1.73 m2, according to the KDOQI guidelines for chronic kidney disease (CKD), and concurrent medications were recorded. Results:ACEinh/ARB were well tolerated in unselected consecutive ACEinh/ARB naïve patients with baseline serum potassium (sK) ≤5.0 mEq/L in a general ambulatory population with 2.5% (23) of 931 developing hyperkalemia (sK ≥5.5 mEq/L). sK ≥6 mEq/L was seen in <1% (7) of patients. The incidence of hyperkalemia was 1.2% in CKD stage 1(1/86), 1.1% in CKD stage 2 (5/469), 3.1% in CKD stage 3 (10/318), and 13.7% in CKD stage 4 (7/51). ACEinh/ARB naïve patients with baseline sK >5.0 mEq/L also tolerated ACEinh/ARB with 7.5% (3/40) developing sK >6.0 mEq/L. Diabetes mellitus did not affect the incidence of hyperkalemia independent of GFR. Conclusions:Although generally safe, ACEinh/ARB poses a small risk for hyperkalemia in patients with reduced GFR. Because the propensity is incremental with declining GFR, these agents should be used with caution in advancing stages of CKD. Presence of diabetes does not affect the development of hyperkalemia.

Optimizing Hemodynamic Support in Septic Shock Using Central and Mixed Venous Oxygen Saturation

Asthma is a disease with distinct phenotypes that have implications for both prognosis and therapy. Epidemiologic studies have demonstrated an association between asthma and obesity. Further studies have shown that obese asthmatics have poor asthma control and more severe asthma. This obese-asthma group may represent a unique phenotype. The mechanisms behind poor asthma control in obese subjects remain unclear, but recent research has focused on adipokines and their effects on the airways as well as the role of oxidative stress. Both surgical and nonsurgical weight loss therapy have shown promising results with improvements in asthma control and decreased asthma severity. Comorbid conditions such as gastroesophageal reflux disease and obstructive sleep apnea may also have a role in poor asthma control in obese asthmatics. Further research is needed to define the mechanisms behind this phenotype which will guide the development of targeted therapies.

Obstructive sleep apnea during rapid eye movement sleep, daytime sleepiness, and quality of life in older men in osteoporotic fractures in men (MrOS) sleep study

Global tissue hypoxia is one of the most important factors in the development of multisystem organ dysfunction. In hemodynamically unstable critically ill patients, central venous oxygen saturation (Scvo(2)) and mixed venous oxygen saturation (Svo(2)) monitoring has been shown to be a better indicator of global tissue hypoxia than vital signs and other clinical parameters alone. Svo(2) is probably more representative of global tissue oxygenation, whereas Scvo(2), is less invasive. Svo(2) and Scvo(2) monitoring can have diagnostic and therapeutic uses in understanding the efficacy of interventions in treating critically ill, hemodynamically unstable patients.