Management of febrile children with urinary tract infections

This study of the management of children with fever and urinary tract infection (UTI) was conducted to identify factors associated with initial admission, outpatient treatment, and outpatient treatment failure. A retrospective chart review identified children 3 months to 16 years of age with an emergency department (ED) diagnosis of cystitis, pyelonephritis, or UTI, a positive urine culture, and an ED temperature of>38°C. Sixty-nine patients (90% female) were studied; 19% were admitted initially. Age younger than 2 years was associated with admission (P < .001). Of those initially discharged, 63% received parenteral antibiotics (usually intramuscular ceftriaxone), followed by oral antibiotics; 9% failed outpatient treatment. Outpatient failure was associated with higher initial temperatures (median 40.1°C v 39.2°C, P = .03, Mann-Whitney U) but was unrelated to age, initial white blood cell count, or use of parenteral antibiotics. These results indicate that most children with fever and UTI do not require hospital admission; those with temperatures of ≥40°C are at increased risk for outpatient failure.     

Determinants of lung volumes in chronic spinal cord injury

Stepp EL, Brown R, Tun CG, Gagnon DR, Jain NB, Garshick E. Determinants of lung volumes in chronic spinal cord injury.

Objective

To characterize determinants of lung volumes in chronic spinal cord injury (SCI).

Design

Cross-sectional.

Setting

VA Boston Healthcare System.

Participants

White men (N=330) with chronic SCI.

Interventions

Not applicable.

Main Outcome Measures

Questionnaire responses and measurements of lung volumes.

Results

Adjusted for SCI severity and stature, greater body mass index (BMI) was associated (all P<.05) with lower total lung capacity (TLC) (−38.7mL·kg⁻¹·m⁻²), functional residual capacity (FRC) (−73.9mL·kg⁻¹·m⁻²), residual volume (RV) (−40.4mL·kg⁻¹·m⁻²), and expiratory reserve volume (ERV) (−32.2mL·kg⁻¹·m⁻²). The effect of BMI on RV was most pronounced in quadriplegia (−72mL·kg⁻¹·m⁻²). Lifetime smoking was associated with a greater FRC (5.3mL/pack-year) and RV (3.1mL/pack-years). The effects of lifetime smoking were also greatest in quadriplegia (11mL/pack-year for FRC; 7.8mL/pack-year for RV). Time since injury, independent of age, was associated with a decrease in TLC, FRC, ERV, and RV (P<.05). Age was not a predictor of TLC once time since injury was considered.

Conclusions

Determinants of FRC, TLC, ERV, and RV in chronic SCI include factors related and unrelated to SCI. The mechanisms remain to be determined but likely involve the elastic properties and muscle function of the respiratory system and perhaps the effects of systemic inflammation related to adiposity. Addressing modifiable factors such as obesity, muscle stiffness, and smoking may improve respiratory morbidity and mortality in SCI by improving pulmonary function.     

Effects of Pilates exercise on trunk strength, endurance and flexibility in sedentary adult females

The objective of this study was to examine the effects of Pilates exercise on abdominal and lower back strength, abdominal muscular endurance and posterior trunk flexibility of sedentary adult females. The body fat and body mass index (BMI) pre- and post-data were also assessed as secondary outcomes. To assess abdominal and lower back strength, posterior trunk flexion and extension data were obtained concentrically on a Biodex isokinetic dynamometer at speeds of 60° and 120° s⁻¹. Abdominal muscular endurance was assessed using the crunch test and posterior trunk flexibility was measured using the sit and reach test. Results of multivariate analysis revealed a significant difference (p<.05) between pre- and post-measures of 60° s⁻¹ flexion/extension and 120° s⁻¹ flexion, and abdominal muscular endurance and posterior trunk flexibility of the exercise group. It can be concluded that there was a positive effect of Modern Pilates mat exercises on abdominal and lower back muscular strength, abdominal muscular endurance and posterior trunk flexibility in sedentary adult females regardless of the fact that the body weight and fat percentages did not differ significantly.     

Urinary N-acetyl-beta-D-glucosaminidase (NAG) in lupus nephritis and rheumatoid arthritis

Increased activity of urinary N-acetyl-beta-D-glucosaminidase (NAG) can be used as an early indicator of damage to the tubular epithelium. Systemic lupus erythematosus (SLE) is a multisystem autoimmune rheumatic disease. Nephritis is known as the most serious complication of SLE and the strongest predictor of poor outcome. In this study urinary NAG excretion was investigated in 24 SLE patients with normal renal function (serum creatinine < or =1.2 mg/dL) and the results were compared with those from 26 untreated patients with rheumatoid arthritis (RA) and 27 healthy controls. The SLE patients were divided into two groups according to their urinary total protein levels: group A consisted of 16 patients with < or =3.5 g/day proteinuria, and group B consisted of eight patients with nephrotic-range proteinuria (>3.5 g/day). Serum and urinary creatinine, total urinary protein levels, and urinary NAG excretion were measured in patients with SLE and RA. In addition, serum C3 and C4 levels were determined in the SLE patients. Renal biopsies were performed in all of the SLE patients. Glomerular lesions were classified according to WHO criteria for lupus nephritis (LN) I-V. The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) was used to assess disease activity. Urinary NAG excretion was significantly higher in the SLE groups than in the healthy controls (P<0.001). In urinary NAG excretion there was also significant difference between SLE groups and RA patients (P<0.001). However, there was no significant difference in NAG excretion between the RA and control groups (P=0.062). Urinary NAG excretion was significantly higher (P<0.05) in group B compared to group A. There were no differences in SLEDAI scores, ages, and serum creatinine levels between study groups (P=0.601, P=0.285, P=0.669, respectively). Elevated SLEDAI values and hypocomplementemia were detected more often in younger patients (P<0.010, r=-0.529 and P<0.010, r=-0.569, respectively). There was a strong positive correlation between proteinuria and urinary NAG activity (P<0.001, r=0.759). These results suggest that the determination of urinary NAG activity may be a useful supplement to the routine biochemical analysis performed on the urine in cases of SLE.     

Electrical neuromodulation improves myocardial perfusion and ameliorates refractory angina pectoris in patients with syndrome X: fad or future?

At present, there is no reliable antianginal drug therapy for patients with cardiac syndrome X. Therefore, the effect of electrical neuromodulation on refractory angina pectoris and myocardial perfusion in cardiac syndrome X was assessed. Eight patients (aged 55±7 years) with heterogeneous myocardial perfusion and no esophageal abnormalities were included. The subjects were nonresponders to antianginal drug therapy. Angina pectoris attacks and myocardial perfusion dynamics were evaluated by positron emission tomography at baseline and following 4 weeks of (transcutaneous electrical nerve stimulation) TENS. Following TENS there was a reduction of angina pectoris episodes (baseline 20±3, TENS 3±1; p=0.012), and short acting nitroglycerin intake per week (baseline 10±3, TENS 2±1; p=0.008). The rate pressure product (mmHgmin⁻¹) during the cold pressor test (CPT) was reduced during TENS (baseline 12 800±1200, TENS 11 500±900; p=0.02). Following TENS, the perfusion reserve ratio between rest and dipyridamole flow increased (baseline 1.59±0.15, TENS 1.90±0.11 mlmin⁻¹×100 g; p=0.05). The coronary vascular resistance had a trend towards a reduction (baseline 0.96±0.04, TENS 0.85±0.06 mmHgmin⁻¹×100 g/ml; p=0.06) during CPT. This observation may suggest that neurostimulation improves angina pectoris with a concomitant improvement of myocardial perfusion in cardiac syndrome X.     

The nitric oxide synthase inhibitor N-nitro-l-arginine decreases defibrillation-induced free radical generation

Objectives: To demonstrate that nitric oxide (NO) contributes to free radical generation after epicardial shocks and to determine the effect of a nitric oxide synthase (NOS) inhibitor, N^G-nitro-l-arginine (l-NNA), on free radical generation. Background: Free radicals are generated by direct current shocks for defibrillation. NO reacts with the superoxide (O₂⁻) radical to form peroxynitrite (O=NOO⁻), which is toxic and initiates additional free radical generation. The contribution of NO to free radical generation after defibrillation is not fully defined. Methods and results: Fourteen open chest dogs were studied. In the initial eight dogs, 40 J damped sinusoidal monophasic epicardial shocks was administered. Using electron paramagnetic resonance, we monitored the coronary sinus concentration of ascorbate free radical (Asc⁻), a measure of free radical generation (total oxidative flux). Epicardial shocks were repeated after l-NNA, 5 mg/kg IV. In six additional dogs, immunohistochemical staining was done to identify nitrotyrosine, a marker of reactive nitrogen species-mediated injury, in post-shock myocardial tissue. Three of these dogs received l-NNA pre-shock. After the initial 40 J shock, Asc⁻ rose 39±2.5% from baseline. After l-NNA infusion, a similar 40 J shock caused Asc⁻ to increase only 2±3% from baseline (P<0.05, post-l-NNA shock versus initial shock). Nitrotyrosine staining was more prominent in control animals than dogs receiving l-NNA, suggesting prevention of O=NOO⁻ formation. Conclusions: NO contributes to free radical generation and nitrosative injury after epicardial shocks; NOS inhibitors decrease radical generation by inhibiting the production of O=NOO⁻.     

Urinary N-acetyl-beta-D-glucosaminidase isoenzyme activity as measured by fast protein liquid chromatography in patients with nephrotic syndrome

Exactly why N-acetyl-beta-D-glucosaminidase (NAG) excretion is increased in patients with nephrotic syndrome with glomerular lesions is poorly understood. Glomeruli contain less NAG than do proximal tubules. In this study, we have tried to measure the NAG isoenzymes automatically by use of the recently developed fast protein liquid chromatography (FPLC) system, followed by column chromatography on DEAE cellulose (Mono Q). Three isoenzyme peaks--B, I + II, and A--were observed for urine from both healthy subjects and nephrotic patients. The B isoenzyme usually constituted about 10% of the total NAG in healthy controls, 30% in nephrotic patients. In contrast, the proportion of the A isoenzyme was inversely related to that of the B isoenzyme when healthy controls and nephrotic patients were compared. Our system for measuring NAG isoenzymes is reproducible and fast, and it should be useful in further studies.     

Diagnostic value of urinary N-acetyl-β-d-glucosaminidase, its isoenzymes and the fractional excretion of sodium following renal transplantation

Daily total urine N-acetyl-β-d-glucosaminidase activity, isoenzyme profile and fractional excretion of sodium were measured in 13 consecutive renal transplant patients. Rejection episodes were clinically diagnosed in 12 patients, 11 of whom (92%) showed an increased enzymuria either before or during the onset of clinical signs. The ratio of the two major isoenzymes (A/B) fell during 10 episodes (83%) and in six of these (50%) increased levels of the minor isoenzyme forms were observed. Increased fractional excretion of sodium was associated with nine (75%) of the episodes. Increased fractional excretion of sodium with a raised total enzymuria accompanied by a reduced A/B ratio and an increased proportion of the minor isoenzyme forms occurred in eight (67%) of the rejection episodes. The use of these measurements in the diagnosis of episodes of acute rejection in renal transplantation is discussed.     

N-acetyl-beta-glucosaminidase isoenzymes in serum and urine of patients with diabetes mellitus

The isoenzyme pattern of N-acetyl-beta-glucosaminidase (NAG) in serum and urine was studied in two groups of patients with diabetes mellitus and in 30 control subjects. Total NAG activity was significantly (P less than 0.001) increased in the serum and urine of the 20 diabetics with vascular complications, but was insignificantly increased in the 20 diabetics without vascular complications. Ion-exchange chromatography demonstrated the presence of two major isoenzymes of NAG, A and B. The proportion of isoenzyme A activity always exceeded that of isoenzyme B. The proportion of isoenzyme B in serum of diabetics was lower than in controls; the reverse was true for urine of diabetics. The NAG isoenzymes pattern may provide additional diagnostic information regarding diabetic status and complications of diabetes.     

Effect of infusion and withdrawl of glucose and insulin on gas exchange in injured ventilated patients

To evaluate the effect induced on gas exchange and on urea excretion by glucose and insulin infusion in injured patients. The magnitude and time necessary for the full development of the metabolic effect were investigated. Six injured patients were investigated. During the first 24 hours, the fasting period, patients received 1 mg/kg^*min of glucose; during the second 24 hours, the treatment period, infusion was increased to about the 95% of the energy production rate; during the last 8 hours, (stop period) the infusion rate was again set to 1 mg/kg^*min. Gas exchange was determined in two consecutive 12-hour series, for 30 minutes every hour, either during a stabilized treatment or after its variation. Urea excretion was determinated on 4-hour samples. With respect to the fasting period, during the last 4 hours of the treatment period, the energy production rate did not vary; urea excretion (−25%) and oxygen consumption (−9%) decreased significantly. Carbon dioxide production (+16%), total respiratory quotient, and minute ventilation (+5%) increased significantly. Carbon dioxide production varied linearly with time (glucose infusion ⁺1.74 mL/min^*m2^*h, P <.05; glucose withdrawal −1.89 mL/min^*m2^*h, P < .01). Minute ventilation decreased only during the withdrawal period by 65 mL/ min^*m2^*h (P < .05). The infusion of glucose and insulin, in an amount slightly lower than the metabolic expenditure, leads to a consistently reduced amino acid catabolism and to a decreased oxygen consumption, without affecting energy requirements. Although it leads to an increase of carbon dioxide production, the measured change is so small and slow that it is not harmful unless there is severe respiratory insufficiency.     

Postreperfusion syndrome: Hypotension after reperfusion of the transplanted liver

Sixty-nine patients undergoing liver transplantation were evaluated to elucidate the relationship between hypotension and physiological changes seen on reperfusion of the grafted liver. Measured variables included hemodynamic profiles, core temperature, serum potassium, ionized calcium levels, arterial blood-gas tensions, and acid-base state. Measurements were taeen 60 minutes after skin incision (baseline), 5 minutes before reperfusion, and 30 seconds and 5 minutes after reperfusion. On the basis of changes in mean arterial pressure (MAP) patients were divided in two groups. Group 1 (n = 49) maintained MAP greater than 70% and group 2 (n = 20) had MAP less than 70% of the baseline value for at least 1 minute within 5 minutes after reperfusion. On reperfusion, changes common to both groups were 27% increase in cardiac filling pressures, 23% base deficit, and 30% serum potassium level and a decrease of 16% in cardiac output and 9% in temperature. Compared with group 1, group 2 had greater decrease in systemic vascular resistance (SVR) (1097 ± 868 and 741 ± 399 dyn · s⁻¹. cm⁻⁵, respectively, P < .05) and higher potassium level (4.5 ± 0.8 and 5.3 ± 0.8 mmol/L,P < .05). Collectively in both groups, there was no correlation between MAP and physiological variables; however, there was a poor correlation with SVR (r = .32, P < .01). Reperfusion hypotension seen in group 2 patients correlated only with a decrease in systemic vascular resistance (r = .5, P < .05). Acute hyperkalemia, hypothermia, and acidosis do not appear to be major causes of reperfusion hypotension.     

Indirect evidence for early widespread gray matter involvement in relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) has traditionally been viewed as an inflammatory demyelinating white matter (WM) disease of the central nervous system. However, recent pathology and MRI studies have shown lesions in the gray matter (GM) as well. To ascertain the extent of GM involvement, we obtained with nonlocalizing proton MR spectroscopy the concentration of N-acetylaspartate (NAA), a metabolite found almost exclusively in neuronal cells, T2-lesion loads, and GM and WM fractions in the entire brain of 71 relapsing–remitting (RR) MS patients (51 women, 20 men, 25–55 years old) and 41 healthy controls (27 women, 14 men, 23–55 years old). The average whole-brain NAA (WBNAA) difference between the patients and the controls was −2.9 mM (−22%, P < 0.0001); range: +1.2 to −7.8 mM (+8% to −63%). The patients' median T2 lesion volume was 5.5 (range: 0.140–28) cm³. GM and WM comprised 50.4 ± 3.8% and 30.4 ± 5.0% (mean ± standard deviation), respectively, of the total brain volume in the patients; 53.8 ± 3.7% and 35.4 ± 4.7% in the controls. Because WM and GM constitute approximately 40% and 60% of the brain parenchyma, respectively, and the NAA concentration in the former is 2/3 of the latter, WBNAA loss greater than 40% × 2/3 = 27% cannot be explained in terms of WM (axonal) pathology alone and must include widespread GM (neuronal) deficits. Therefore, the concept of MS, even at its earlier stages, as a WM disease might need to be reexamined.     

Relationship between ventilator-associated pneumonia and intramucosal gastric pHi: A case-control study

Prior investigations have suggested a clear relationship between nosocomial pneumonia and intramucosal gastric pH (pHi), a probable marker of bacterial translocation. We studied 33 patients (18 with pneumonia and 15 without) admitted to an intensive care unit and hospitalized longer than 72 hours with the aim of assessing the relationship between nosocomial pneumonia, pHi, and outcome. pHi was estimated at the time of inclusion of patients into the study. Arterial pH (pHa) and bicarbonate and stomach pH and tonometer Ptco₂ were also recorded. Values of <7.32 or ΔpHa - pHi of>+0.06 were used to differentiate between normal and low pHi. Quantitative cultures of pharyngeal swabs, gastric lumen, and protected specimen brush from lower airways were also done. The mean pHi values were 7.397 ± 0.105 (range, 7.14 to 7.53) and 7.452 ± 0.059 (range, 7.37 to 7.56) for patients with and without pneumonia, respectively (P = .073). Five patients, all with pneumonia, had pHi < 7.32. No patients without pneumonia had pHi < 7.32 (P = .04). The mean ΔpHa - pHi was 0.04 ± 0.07 (range, −0.11 to 0.13) and 0.05 ± 0.09 (range, −0.09 to 0.28; P = .72) for patients with and without pneumonia, respectively. However, there were significant differences when tonometer Ptco₂ values of both groups were compared (38.9 ± 8.3 and 30.6 ± 4.7 mm Hg, respectively; P = .025). Patients with pneumonia had higher alkaline gastric lumen pH (5.2 ± 1.0) than those without pneumonia (3.8 ± 1.4; P = .006). Nonsurvivors (n = 7) had more acidic pHi (7.33 ± 0.11) than survivors (7.44 ± 0.06; P = .045). The mean gastric lumen bacterial concentration was 4.14 ± 1.01 Log₁₀ CFU/mL in patients with pneumonia and 4.28 ± 1.22 Log₁₀ CFU/mL in patients without pneumonia (P = NS). When patients with and without intramucosal gastric acidosis (pHi < 7.32) were compared, the gastric bacterial burden was 4.42 ± 0.82 Log₁₀ CFU/mL and 4.32 ± 1.03 Log₁₀ CFU/mL (P = .08), respectively. Most patients with nosocomial pneumonia had no associated intramucosal gastric acidosis. However, low pHi was associated with increased mortality.     

Different effects of sodium bicarbonate and an alternate buffer (Carbicarb) in normal volunteers

The effects of sodium bicarbonate and Carbicarb (International Medical Systems, South El Monte, CA) infusions on hemodynamic and systemic acid-base homeostasis were compared in six normal volunteers. Neither sodium bicarbonate nor Carbicarb caused any major adverse side effects or had a significant effect on heart rate and blood pressure. However, during the first 3 minutes following infusion, sodium bicarbonate induced marked increases in respiratory carbon dioxide excretion above baseline (VCO₂) compared with Carbicarb (+0.61 ± 0.10 v +0.01 ± 0.10 mmol/kg, P < .01) and increases in PaCO₂, whereas Carbicarb was associated with a transient decrease in PaCO₂ (+11.8 ± 1.6v −5.0 ± .8 mm Hg, P < .01). We calculated that approximately 31% of sodium bicarbonate, but virtually no Carbicarb, was excreted as expired CO₂. These data suggest that if used clinically, Carbicarb therapy might not be associated with the deleterious effects of sodium bicarbonate that are postulated to result from CO₂ generation.     

In vivo Breast Sound-Speed Imaging with Ultrasound Tomography

We discuss a bent-ray ultrasound tomography algorithm with total-variation (TV) regularization. We have applied this algorithm to 61 in vivo breast datasets collected with our in-house clinical prototype for imaging sound-speed distributions in the breast. Our analysis showed that TV regularization could preserve sharper lesion edges than the classic Tikhonov regularization. Furthermore, the image quality of our TV bent-ray sound-speed tomograms was superior to that of the straight-ray counterparts for all types of breasts within BI-RADS density categories 1 through 4. Our analysis showed that the improvements for average sharpness (in the unit of (m · s)⁻¹) of lesion edges in our TV bent-ray tomograms are between 2.1 to 3.4-fold compared with the straight ray tomograms. Reconstructed sound-speed tomograms illustrated that our algorithm could successfully image fatty and glandular tissues within the breast. We calculated the mean sound-speed values for fatty tissue and breast parenchyma as 1422 ± 9 m/s (mean ± SD) and1487 ± 21 m/s, respectively. Based on 32 lesions in a cohort of 61 patients, we also found that the mean sound-speed for malignant breast lesions (1548 ± 17 m/s) was higher, on average, than that of benign ones (1513 ± 27 m/s) (one-sided p < 0.001). These results suggest that, clinically, sound-speed tomograms can be used to assess breast density (and therefore, breast cancer risk), as well as detect and help differentiate breast lesions. Finally, our sound-speed tomograms may also be a useful tool to monitor the clinical response of breast cancer patients to neo-adjuvant chemotherapy. (E-mail: lic@karmanos.org)     

Mapping the effect of APOE ε4 on gray matter loss in Alzheimer's disease in vivo

Previous studies suggest that in Alzheimer's disease (AD) the Apolipoprotein E (APOE) ε4 allele is associated with greater vulnerability of medial temporal lobe structures. However, less is known about its effect on the whole cortical mantle. Here we aimed to identify APOE-related patterns of cortical atrophy in AD using an advanced computational anatomy technique. We studied 15 AD patients carriers (ε4+, age: 72 ± 10 SD years, MMSE: 20 ± 3 SD) and 14 non-carriers (ε4−, age: 69 ± 9, MMSE: 20 ± 5) of the ε4 allele and compared them to 29 age-and-sex matched controls (age: 70 ± 9, MMSE: 28 ± 1). Each subject underwent a clinical evaluation, a neuropsychological battery, and high-resolution MRI. UCLA's cortical pattern matching technique was used to identify regions of local cortical atrophy. ε4+ and ε4− patients showed similar performance on neuropsychological tests (p > .05, t-test). Diffuse cortical atrophy was detected for both ε4+ (p = .0001, permutation test) and ε4− patients (p = .0001, permutation test) relative to controls, and overall gray matter loss was about 15% in each patients group. Differences in gray matter loss between carriers and non-carriers mapped to the temporal cortex and right occipital pole (20% greater loss in carriers) and to the posterior cingulate, left orbitofrontal and dorsal fronto-parietal cortex (5–15% greater loss in non-carriers). APOE effect in AD was not significant (p > .74, ANOVA), but a significant APOE by region (temporal vs fronto-parietal cortex) interaction was detected (p = .002, ANOVA), in both early and late-onset patients (p < .05, ANOVA). We conclude that the ε4 allele modulates disease phenotype in AD, being associated with a pattern of differential temporal and fronto-parietal vulnerability.     

Effect of ethanol on the transport of methylene blue through stratum corneum

Diffusion of methylene blue (MB) dissolved in both saline (0.9% NaCl) and 40% ethanol/saline in skin was investigated with reflectance spectroscopy. Experiments have been carried out with rat skin samples in vitro at 20 °C. The present studies have shown that 40% concentration of ethanol in solution greatly enhances transport of MB across stratum corneum. The diffusion coefficient of MB in skin in vitro has been estimated. The average value of diffusion coefficient is (2.2±0.9)×10⁻⁶ cm²/s.     

A novel approach to monitor tissue perfusion: Bladder mucosal P 2, P 2, and pHi during ischemia and reperfusion

The purpose of this study is to determine if monitoring urinary bladder P ₂, P ₂, and calculated intramucosal pH would be a reliable index of tissue perfusion. This nonrandomized controlled study was conducted in a laboratory at a university medical center. Eight immature female Yorkshire pigs were studied with T-9 aortic cross-clamping for 30 minutes followed by a 60-minute period of reperfusion. Cystotomy was performed for placement of a Foley catheter and Paratrend 7 o₂/co₂ sensor. Baseline hemodynamic and metabolic measurements were obtained along with measurements of bladder mucosal Pot and P ₂ (mean ± SEM). Blood flow measured with microspheres confirmed absence of blood flow during occlusion and hyperemia during reperfusion. Bladder mucosal P ₂ decreased from 42 ± 14.0 mm Hg (5.6 kPa)to 1.3 ± 1.3 mm Hg(1.4 kPa) during the 30-minute interval of ischemia. This was followed by an increase of bladder P ₂ to greater than baseline values at the end of the reperfusion period. Bladder mucosal P ₂ increased from 57 ± 4.7 mm Hg (7.6 kPa) to 117 ± 7.1 mm Hg (15.6 kPa) (P < .05) during ischemia. During reperfusion the P ₂ returned to baseline levels (55 ± 4.0 mm Hg [7.3 kPa]). Calculated bladder mucosal pHi declined from 7.31 ± 0.04 to 7.08 ± 0.05 (P < .05) during the ischemic period and after reperfusion pHi was 7.17 ± 0.03. Monitoring urinary bladder P ₂, P ₂, or calculating pHi may provide a simple and reliable means of monitoring tissue perfusion.     

Hemodynamic tolerance of hemodialysis in septic patients with acute renal failure: comparison between recirculating and single-pass bicarbonate hemodialysis

Septic patients with acute renal failure (ARF) are especially intolerant to acetate hemodialysis (HD). Hemodynamic tolerance in septic patients is improved by using bicarbonate dialysis and high Na concentration dialysate. The potential improvement of hemodynamic tolerance with recirculating v single-pass bicarbonate HD (BiHD) has not been evaluated in such patients. We then compared the hemodynamic tolerance in a randomized cross-over study, using a pulmonary artery catheter and biologic changes during the two types of HD in eight severe septic patients with ARF. Patients were dialysed for four hours with a 1 m²1 cuprophan dialyzer, alternatively using single-pass and recirculating system. No absorbent cartridge was used in recirculating BiHD. Intravascular volume expansion (IVE) was used as needed to maintain a systolic arterial pressure of at least 80 mm Hg. Similar doses of catecholamines (dopamine essentially) and equal ultrafiltration rate (mean, 1.55 ± 0.61 for four hours) were used during the two types of dialysis in each patient. No hemodynamic parameter was significantly different between the two procedures, but IVE was lower (370 ± 550 mL v 740 ± 590 mL; P < .05) and weight loss higher (1.06 ± 0.88 kg v 0.68 ± 0.99 kg; P < .05) in recirculating BiHD than in single-pass BiHD. No biologic differences were found between recirculating and single-pass BiHD except for a lower decrease of blood urea (Δ, 10.5 ± 3.4 μmol/L v 12.8 ± 4.9 mmol/L; P <.05) and creatinine (Δ, 107 ± 40 μmol/L v 153 ± 69 μmol/L; P < .05) in recirculating BiHD. Recirculating BiHD was better tolerated than single-pass BiHD, requiring less IVE. This lesser IVE during recirculating BiHD with similar decrease in pulmonary wedge pressure suggests a venoconstrictor effect. This venoconstrictor effect is likely due to a lower loss of catecholamines (dopamine) in the dialysate. Recirculating BiHD is better tolerated than single pass, providing higher weight loss. This procedure is particularly interesting in patients with cardiovascular instability, especially after septic shock.     

Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients

Recent observations have highlighted errors in the thermodilution technique of measuring cardiac output. Thus, cardiac output measurements using transesophageal echocardiography and the Fick method were compared with simultaneous thermodilution measurements. In 13 mechanically ventilated critically ill patients, cardiac output was determined simultaneously using (1) transesophageal echocardiography (CO_TEE), (2) the Fick method (CO_FICK), and (3) thermodilution (CO_TD) immediately before and after a rapid infusion of 500 mL of saline. Left ventricular end-diastolic and end-systolic areas were measured using the transesophageal echocardiographic transgastric short axis view, and CO_TEE was calculated from the corresponding volumes. Absolute cardiac output values and the changes from before to after saline infusion (ΔCO) were compared using analysis of variance, linear regression, and the Bland and Altman method. There were no significant differences between CO_TEE (8.0 ± 3.4), CO_FICK (8.4 ± 3.3), and CO_TD (8.3 ± 3.0) or between ΔCO_TEE, ΔCO_FCK, and ΔCO_TD using analysis of variance. However, correlations between CO_TEE and CO_TD (r² = 0.46; P < .00001), CO_FICK and CO_TD (r² = 0.46; P < .00001), and CO_TEE and CO_FICK (r² = 0.42; P < .00001) were only moderately good. Using the method of Bland and Altman, the mean difference (±2 standard deviations) between CO_TEE and CO_TD was 0.3 ± 4.3 L/min, between CO_FICK and CO_TD was −1.0 ± 3.8 L/min, and between CO_TEE and CO_FICK was 0.6 ± 5.6 L/min, whereas the difference between ΔCO_TEE and ΔCO_TD was 0% ± 26%, between ΔCO_FICK and ΔCO_TD was 9% ± 46%, and between ΔCO_TEE and ΔCO_FICK was 8% ± 39%. There are substantial differences in cardiac output as measured by these three methods, best demonstrated using the method of Bland and Altman. The variability of cardiac output and its derivatives (eg, oxygen delivery) should be borne in mind when making clinical decisions on individual patients.