Hemostatic effects of a dextran-based priming solution for cardiopulmonary bypass: A secondary analysis of a randomized clinical trial

INTRODUCTION

Intravascular fluids administered to patients may influence hemostasis. In patients undergoing cardiac surgery with cardiopulmonary bypass, the heart-lung machine is primed with 1300 ml of fluid. We assessed postoperative coagulation and platelet function in patients randomized to two different priming solutions, one colloid-based (dextran 40) and one crystalloid-based.

MATERIALS AND METHODS

Eighty-four elective cardiac surgery patients were randomized to either a dextran-based prime or Ringer's acetate with added mannitol. Blood samples were collected before, and 2 and 24 h after cardiopulmonary bypass. Coagulation was assessed by standard coagulation tests and rotational thromboelastometry. Platelet function was assessed with impedance aggregometry. Bleeding volumes and transfusion requirements were recorded.

RESULTS

Comparing the groups 2 h after bypass, the dextran group showed lower hemoglobin concentration, hematocrit, platelet count, and fibrinogen concentration, and higher INR and aPTT, as well as longer clot formation time (+41 ± 21 % vs. +8 ± 18 %, p < 0.001) and a larger reduction in fibrinogen-dependent clot strength (-37 ± 12 % vs. -7 ± 20 %, p < 0.001). Adenosine diphosphate-dependent platelet activation was reduced in the dextran group but not in the crystalloid group 2 h after bypass (-14 ± 29 % vs. -1 ± 41 %, p = 0.041). No significant between-group differences in hemostatic variables remained after 24 h, and no significant differences in perioperative bleeding volumes, re-explorations for bleeding, or transfusion rates were observed.

CONCLUSIONS

Compared to a crystalloid solution, a dextran-based prime had measurable negative impact on hemostatic variables but no detectable increase in bleeding volume or transfusion requirements in cardiac surgery patients.

Inspiratory and end-expiratory effects of lung recruitment in the prone position on dorsal lung aeration - new physiological insights in a secondary analysis of a randomised controlled study in post-cardiac surgery patients

Background

Cardiac surgery produces dorso-basal atelectasis and ventilation/perfusion mismatch, associated with infection and prolonged intensive care. A postoperative lung volume recruitment manoeuvre to decrease the degree of atelectasis is routine. In patients with severe respiratory failure, prone positioning and recruitment manoeuvres may increase survival, oxygenation, or both. We compared the effects of lung recruitment in prone vs supine positions on dorsal inspiratory and end-expiratory lung aeration.

Methods

In a prospective RCT, 30 post-cardiac surgery patients were randomly allocated to recruitment manoeuvres in the prone (n=15) or supine position (n=15). The primary endpoints were late dorsal inspiratory volume (arbitrary units [a.u.]) and left/right dorsal end-expiratory lung volume change (a.u.), prone vs supine after extubation, measured using electrical impedance tomography. Secondary outcomes included left/right dorsal inspiratory volumes (a.u.) and left/right dorsal end-expiratory lung volume change (a.u.) after prone recruitment and extubation.

Results

The last part of dorsal end-inspiratory volume after extubation was higher after prone (49.1 a.u.; 95% confidence interval [CI], 37.4-60.6) vs supine recruitment (24.2 a.u.; 95% CI, 18.4-29.6; P=0.024). Improvement in left dorsal end-expiratory lung volume after extubation was higher after prone (382 a.u.; 95% CI, 261-502) vs supine recruitment (-71 a.u., 95% CI, -140 to -2; n=15; P<0.001). After prone recruitment, left vs right predominant end-expiratory dorsal lung volume change disappeared after extubation. However, both left and right end-expiratory volumes were higher in the prone group, after extubation.

Conclusions

Recruitment in the prone position improves dorsal inspiratory and end-expiratory lung volumes after cardiac surgery.

Clinical trial registration

NCT03009331.

Lung recruitment in the prone position after cardiac surgery: a randomised controlled study

BACKGROUND

Atelectasis after cardiac surgery is common and promotes ventilation/perfusion mismatch, infection, and delayed discharge from critical care. Recruitment manoeuvres are often performed to reduce atelectasis. In severe respiratory failure, recruitment manoeuvres in the prone position may increase oxygenation, survival, or both. We compared the effects of recruitment manoeuvres in the prone vs supine position on lung aeration and oxygenation in cardiac surgical patients.

METHODS

Subjects were randomised to recruitment manoeuvres (40 cm H₂O peak inspiratory pressure and 20 cm H₂O PEEP for 30 s) in either the prone or supine position after uncomplicated cardiac surgery. The co-primary endpoints were lung aeration (end-expiratory lung volume measured by electrical impedance tomography (arbitrary units [a.u.]) and lung oxygenation (ratio of arterial oxygen partial pressure to fractional inspired oxygen [Pao₂/FiO₂ ratio]). Secondary outcomes included postoperative oxygen requirement and adverse events.

RESULTS

Thirty subjects (27% female; age, 48-81 yr) were recruited. Dorsal lung tidal volume was higher after prone recruitment manoeuvres (363 a.u.; 95% confidence intervals [CI], 283-443; n=15) after extubation, compared with supine recruitment manoeuvres (212 a.u.; 95% CI, 170-254; n=15; P<0.001). Prone recruitment manoeuvres increased dorsal end-expiratory lung volume by 724 a.u. (95% CI, 456-992) after extubation, compared with 163 a.u. decrease (95% CI, 73-252) after supine recruitment manoeuvres (P<0.001). The Pao₂/FiO₂ ratio after extubation was higher after prone recruitment manoeuvres (46.6; 95% CI, 40.7-53.0) compared with supine recruitment manoeuvres (39.3; 95% CI, 34.8-43.8; P=0.04). Oxygen therapy after extubation was shorter after prone (33 h [13]) vs supine recruitment manoeuvres (52 h [22]; P=0.01). No adverse events occurred.

CONCLUSIONS

Recruitment manoeuvres in the prone position after cardiac surgery improve lung aeration and oxygenation.

CLINICAL TRIAL REGISTRATION

NCT03009331.

Effect of different asthma treatments on risk of cold-related exacerbations

Common colds often trigger asthma exacerbations. The present study compared cold-related severe exacerbations during budesonide/formoterol maintenance and reliever therapy, and different regimens of maintenance inhaled corticosteroids (ICS), with or without long-acting β(2)-agonists (LABA), and with as-needed short-acting β(2)-agonists (SABA) or LABA. Reported colds and severe exacerbations (defined by oral corticosteroid use and/or hospitalisation/emergency room visit) were assessed for 12,507 patients during 6-12 months of double-blind treatment. Exacerbations occurring ≤14 days after onset of reported colds were analysed by a Poisson model. The incidence of colds was similar across treatments. Asthma symptoms and reliever use increased during colds. Budesonide/formoterol maintenance and reliever therapy reduced severe cold-related exacerbations by 36% versus pooled comparators plus SABA (rate ratio (RR) 0.64; p=0.002), and for individual treatment comparisons, by 52% versus the same maintenance dose of ICS/LABA (RR 0.48; p<0.001); there were nonsignificant reductions versus higher maintenance doses of ICS or ICS/LABA (RR 0.83 and 0.72, respectively). As-needed LABA did not reduce cold-related exacerbations versus as-needed SABA (RR 0.96). Severe cold-related exacerbations were reduced by budesonide/formoterol maintenance and reliever therapy compared with ICS with or without LABA and with as-needed SABA. Subanalyses suggested the importance of the ICS component in reducing cold-related exacerbations. Future studies should document the cause of exacerbations, in order to allow identification of different treatment effects.

Risks of pneumonia in patients with asthma taking inhaled corticosteroids

RATIONALE

Inhaled corticosteroids (ICS) are the mainstay of asthma treatment. Studies in chronic obstructive pulmonary disease reported increased rates of pneumonia with ICS. Concerns exist about an increased pneumonia risk in patients with asthma taking ICS.

OBJECTIVES

To evaluate the risks of pneumonia in patients with asthma taking ICS.

METHODS

A retrospective analysis evaluated studies of the ICS budesonide in asthma. The primary data set were all double-blind, placebo-controlled trials lasting at least 3 months, involving budesonide (26 trials, n = 9,067 for budesonide; n = 5,926 for the comparator) sponsored by AstraZeneca. A secondary data set evaluated all double-blind trials lasting at least 3 months but without placebo control (60 trials, n = 33,496 for budesonide, n = 2,773 for fluticasone propionate). Cox proportional hazards regression modeling was used to estimate the relative effect of ICS on pneumonia adverse events (AEs) or serious adverse events (SAEs).

MEASUREMENTS AND MAIN RESULTS

In the primary data set, the occurrence of pneumonia AEs was 0.5% (rate 10.0 events/1,000 patient-years [TPY]) for budesonide and 1.2% (19.3 per TPY) for placebo (hazard ratio, 0.52; 95% confidence interval, 0.36-0.76; P < 0.001); the occurrence of pneumonia SAEs was 0.15% (2.9 per TPY) for budesonide and 0.13% (2.1 per TPY) for placebo (hazard ratio, 1.29; 95% confidence interval, 0.53-3.12; P = 0.58). In the secondary data set, the percentage of patients reporting pneumonia AEs was 0.70% (12.7 per TPY), whereas the percentage of patients reporting pneumonia SAEs was 0.17% (3.1 per TPY). There was no increased risk with higher budesonide doses or any difference between budesonide and fluticasone.

CONCLUSIONS

There is no increased risk of pneumonia in patients with asthma, identified as an AE or SAE, in clinical trials using budesonide.

Norepinephrine causes a pressure-dependent plasma volume decrease in clinical vasodilatory shock

BACKGROUND

Recent experimental studies have shown that a norepinephrine-induced increase in blood pressure induces a loss of plasma volume, particularly under increased microvascular permeability. We studied the effects of norepinephrine-induced variations in the mean arterial pressure (MAP) on plasma volume changes and systemic haemodynamics in patients with vasodilatory shock.

METHODS

Twenty-one mechanically ventilated patients who required norepinephrine to maintain MAP > or =70 mmHg because of septic/postcardiotomy vasodilatory shock were included. The norepinephrine dose was randomly titrated to target MAPs of 60, 75 and 90 mmHg. At each target MAP, data on systemic haemodynamics, haematocrit, arterial and mixed venous oxygen content and urine flow urine were measured. Changes in the plasma volume were calculated as 100 x (Hct(pre)/Hct(post)-1)/ (1-Hct(pre)), where Hct(pre) and Hct(post) are haematocrits before and after intervention.

RESULTS

Norepinephrine doses to obtain target MAPs of 60, 75 and 90 mmHg were 0.20+/-0.18, 0.29+/-0.18 and 0.42+/-0.31 microg/kg/min, respectively. From 60 to 90 mmHg, increases in the cardiac index (15%), systemic oxygen delivery index (25%), central venous pressure (CVP) (20%) and pulmonary artery occlusion pressure (33%) were seen, while the intrapulmonary shunt fraction was unaffected by norepinehrine. Plasma volume decreased by 6.5% and 9.4% (P<0.0001) when blood pressure was increased from 60 to 75 and 90 mmHg, respectively. MAP (P<0.02) independently predicted the decrease in plasma volume with norepinephrine but not CVP (P=0.19), cardiac index (P=0.73), norepinephrine dose (P=0.58) or urine flow (P=0.64).

CONCLUSIONS

Norepinephrine causes a pressure-dependent decrease in the plasma volume in patients with vasodilatory shock most likely caused by transcapillary fluid extravasation.

Budesonide and the risk of pneumonia: a meta-analysis of individual patient data

BACKGROUND

Concern is continuing about increased risk of pneumonia in patients with chronic obstructive pulmonary disease (COPD) who use inhaled corticosteroids. We aimed to establish the effects of inhaled budesonide on the risk of pneumonia in such patients.

METHODS

We pooled patient data from seven large clinical trials of inhaled budesonide (320-1280 mug/day), with or without formoterol, versus control regimen (placebo or formoterol alone) in patients with stable COPD and at least 6 months of follow-up. The primary analysis compared treatment groups for the risk of pneumonia as an adverse event or serious adverse event during the trial or within 15 days of the trial end. Cox proportional hazards regression was used to analyse the data on an intention-to-treat basis. Data were adjusted for patients' age, sex, smoking status, body-mass index, and postbronchodilator percent of predicted forced expiratory volume in 1 s (FEV(1)).

FINDINGS

We analysed data from 7042 patients, of whom 3801 were on inhaled budesonide and 3241 were on control treatment, with 5212 patient-years of exposure to treatment. We recorded no significant difference between treatment groups for the occurrence of pneumonia as an adverse event (3% [n=122 patients] vs 3% [n=103]; adjusted hazard ratio 1.05, 95% CI 0.81-1.37) or a serious adverse event (1% [n=53] vs 2% [n=50]; 0.92, 0.62-1.35), or for time to pneumonia as an adverse event (log-rank test 0.94) or a serious adverse event (0.61). Increasing age and decreasing percent of predicted FEV(1) were the only two variables that were significantly associated with occurrence of pneumonia as an adverse event or a serious adverse event.

INTERPRETATION

Budesonide treatment for 12 months does not increase the risk of pneumonia in patients with COPD during that time and therefore is safe for clinical use in such patients.

FUNDING

Michael Smith Foundation for Health Research.

Vasopressin decreases intestinal mucosal perfusion: a clinical study on cardiac surgery patients in vasodilatory shock

BACKGROUND

Low to moderate doses of vasopressin have been used in the treatment of cathecholamine-dependent vasodilatory shock in sepsis or after cardiac surgery. We evaluated the effects of vasopressin on jejunal mucosal perfusion, gastric-arterial pCO2 gradient and the global splanchnic oxygen demand/supply relationship in patients with vasodilatory shock after cardiac surgery.

METHODS

Eight mechanically ventilated patients, dependent on norepinephrine to maintain mean arterial pressure (MAP) > or = 60 mmHg because of septic/post-cardiotomy vasodilatory shock and multiple organ failure after cardiac surgery, were included. Vasopressin was sequentially infused at 1.2, 2.4 and 4.8 U/h for 30-min periods. Norepinephrine was simultaneously decreased to maintain MAP at 75 mmHg. At each infusion rate of vasopressin, data on systemic hemodynamics, jejunal mucosal perfusion, jejunal mucosal hematocrit and red blood cell velocity (laser Doppler flowmetry) as well as gastric-arterial pCO2 gradient (gastric tonometry) and splanchnic oxygen and lactate extraction (hepatic vein catheter) were obtained.

RESULTS

The cardiac index, stroke volume index and systemic oxygen delivery decreased and systemic vascular resistance and systemic oxygen extraction increased significantly, while the heart rate or global oxygen consumption did not change with increasing vasopressin dose. Jejunal mucosal perfusion decreased and the arterial-gastric-mucosal pCO2 gradient increased, while splanchnic oxygen or lactate extraction or mixed venous-hepatic venous oxygen saturation gradient were not affected by increasing infusion rates of vasopressin.

CONCLUSIONS

Infusion of low to moderate doses of vasopressin in patients with norepinephrine-dependent vasodilatory shock after cardiac surgery induces an intestinal and gastric mucosal vasoconstriction.

Safety of inhaled budesonide: clinical manifestations of systemic corticosteroid-related adverse effects

Inhaled corticosteroid (ICS) therapy is central to the long-term management of asthma and is extensively used in the management of chronic obstructive pulmonary disease (COPD). While administration via inhalation limits systemic exposure compared with oral or injected corticosteroids and, therefore, the risk of systemic corticosteroid-related adverse effects, concerns over the long-term safety of ICS persist. The assessment of the long-term effects of ICS therapy requires considerable research effort over years or even decades. Surrogate markers/predictors for clinical endpoints such as adrenal crisis, reduced final height and fractures have been identified for use in relatively short-term studies. However, the predictive value of such markers remains questionable.Inhaled budesonide has been available since the early 1980s and there is a considerable evidence base investigating the safety of this agent. To assess the long-term safety of inhaled budesonide therapy in terms of the actual incidence of the clinical endpoints adrenal crisis/insufficiency, reduced final height, fractures and pregnancy complications, we undertook a review of the scientific literature. The external databases BIOSIS, Cochrane Central Register of Controlled Trials, Current Contents, EMBASE, International Pharmaceutical Abstracts and MEDLINE were searched, in addition to AstraZeneca's internal product literature database Planet, up to 29 February 2008. Only original articles of epidemiological studies, national surveys, clinical trials and case reports concerning inhaled budesonide were included.Eight surveys of adrenal crisis were found. The only survey with specified criteria for diagnosis involved 2912 paediatricians and endocrinologists and revealed 33 patients with adrenal crisis associated with ICS therapy; only one patient used budesonide (in co-treatment with fluticasone propionate). In addition, 14 case reports of adrenal crisis in budesonide-treated patients were found. In only two of these, budesonide was used at recommended doses and in the absence of interacting medication.Three retrospective studies and one prospective study assessing final height were found. None of them showed any reduced final height in patients receiving inhaled budesonide during childhood or adolescence.Seventeen epidemiological studies investigating the risk of fractures were found. When adjusting for confounding factors, they did not provide any unequivocal data for an increased fracture risk with budesonide. Four prospective placebo-controlled clinical trials of 2-6 years duration with inhaled budesonide in patients with asthma or COPD were found. None of the studies identified any association between inhaled budesonide and increased risk for fractures.Four studies using data from the Swedish birth and health registries showed there was no increased risk for congenital malformations, cardiovascular defects, decreased gestational age, birth weight or birth length among infants born to women using inhaled budesonide during pregnancy compared with the general population. This was confirmed by five observational studies in Australia, Canada, Hungary, Japan and the US. Similarly, one randomized clinical trial comparing pregnancy outcomes among asthma patients receiving inhaled budesonide or placebo did not demonstrate any difference in outcome of pregnancy.In summary, based on 25 years of experience with different doses and in different populations, inhaled budesonide therapy only in very rare cases appears to be associated with an increased risk of adrenal crisis, reduction in final height, increases in the number of fractures or complications during pregnancy.

NOREPINEPHRINE AND INTESTINAL MUCOSAL PERFUSION IN VASODILATORY SHOCK AFTER CARDIAC SURGERY

Patients with norepinephrine-dependent vasodilatory shock after cardiac surgery (n = 10) were compared with uncomplicated postcardiac surgery patients (n = 10) with respect to jejunal mucosal perfusion, gastric-arterial PCO2 gradient, and splanchnic oxygen demand/supply relationship. Furthermore, the effects of norepinephrine-induced variations in MAP on these variables were evaluated in vasodilatory shock. Norepinephrine infusion rate was randomly and sequentially titrated to target MAPs of 60, 75, and 90 mmHg (0.25 +/- 0.24, 0.37 +/- 0.21, and 0.55 +/- 0.39 microg/kg per minute, respectively). Data on jejunal mucosal perfusion, jejunal mucosal hematocrit, and red blood cell (RBC) velocity (laser Doppler flowmetry) as well as gastric-arterial PCO2 gradient (gastric tonometry) and splanchnic oxygen and lactate extraction (hepatic vein catheter) were obtained. Splanchnic oxygen extraction was 71 +/- 16% in the vasodilatory shock group and 41 +/- 9% in the control group (P < 0.001), whereas splanchnic lactate extraction did not differ between the two groups. Jejunal mucosal perfusion (61%; P < 0.001), RBC velocity (35%; P < 0.01), and gastric-arterial mucosal PCO2 gradient (150%; P < 0.001) were higher in the vasodilatory shock group compared with those of the control group. Jejunal mucosal perfusion, jejunal mucosal hematocrit, RBC velocity, gastric-arterial mucosal PCO2 gradient, splanchnic oxygen extraction, and splanchnic lactate extraction were not affected by increasing infusion rates of norepinephrine. In patients with norepinephrine-dependent vasodilatory shock after cardiac surgery, intestinal mucosal perfusion was higher, whereas splanchnic and gastric oxygen demand/supply relationships were impaired compared with postoperative controls, suggesting that intestinal mucosal perfusion is prioritized in vasodilatory shock. Increasing MAP from 60 to 90 mmHg with norepinephrine in clinical vasodilatory shock does not affect intestinal mucosal perfusion and gastric or global splanchnic oxygen demand/supply relationships.

Possible protection by inhaled budesonide against ischaemic cardiac events in mild COPD

Epidemiological studies have indicated that chronic obstructive pulmonary disease (COPD) may be associated with an increased incidence of ischaemic cardiac events. The current authors performed a post hoc analysis of the European Respiratory Society's study on Chronic Obstructive Pulmonary Disease (EUROSCOP); a 3-yr, placebo-controlled study of an inhaled corticosteroid budesonide 800 microg.day(-1) in smokers (mean age 52 yrs) with mild COPD. The current study evaluates whether long-term budesonide treatment attenuates the incidence of ischaemic cardiac events, including angina pectoris, myocardial infarction, coronary artery disorder and myocardial ischaemia. Among the 1,175 patients evaluated for safety, 49 (4.2%) patients experienced 60 ischaemic cardiac events. Patients treated with budesonide had a significantly lower incidence of ischaemic cardiac events (18 out of 593; 3.0%) than those receiving placebo (31 out of 582; 5.3%). The results of the present study support the hypothesis that treatment with inhaled budesonide reduces ischaemic cardiac events in patients with mild chronic obstructive pulmonary disease.

Autoregulation of Human Jejunal Mucosal Perfusion During Cardiopulmonary Bypass

Animal studies have suggested that autoregulation of intestinal blood flow is severely impaired during cardiopulmonary bypass (CPB). We investigated the jejunal mucosal capacity to autoregulate perfusion during nonpulsatile CPB (34 degrees C) in 10 patients undergoing elective cardiac surgery. Changes in mean arterial blood pressure (MAP) were induced by altering the CPB flow rate randomly for periods of 3 min from 2.4 L/min/m2 to either 1.8 or 3.0 L/min/m2. Jejunal mucosal perfusion (JMP) was continuously recorded by laser Doppler flowmetry. A typical pattern of flow motion (vasomotion) was recorded in all patients during CPB. Variations in CPB flow rates caused no significant changes in mean JMP, jejunal mucosal hematocrit, or red blood cell velocity within a range of MAP from 50 +/- 15 to 74 +/- 16 mm Hg. The vasomotion frequency and amplitude was positively correlated with CPB flow rate. IV injections of prostacyclin (10 microg, Flolan) blunted vasomotion and increased JMP from 192 +/- 53 to 277 +/- 70 (P < 0.05) perfusion units despite a reduction in MAP from 59 +/- 12 to 45 +/- 10 mm Hg (P < 0.05). Prostacyclin-induced vasodilation resulted in loss of mucosal autoregulation (pressure-dependent perfusion). We conclude that autoregulation of intestinal mucosal perfusion is maintained during CPB in humans.

Vasopressors and intestinal mucosal perfusion after cardiac surgery: Norepinephrine vs. phenylephrine

OBJECTIVES

To evaluate the potential differential effects of norepinephrine, an alpha1-, beta1-, and beta2-receptor agonist, to the alpha1-agonist phenylephrine on jejunal mucosal perfusion, gastric-arterial PCO2 gradient, and the global splanchnic oxygen demand-supply relationship after cardiac surgery.

DESIGN

A randomized, prospective, interventional crossover study.

SETTING

A university cardiothoracic intensive care unit.

PATIENTS

Ten patients were studied during propofol sedation and mechanical ventilation after uncomplicated coronary artery bypass surgery.

INTERVENTIONS

Each patient received randomly and sequentially norepinephrine (0.052+/-0.009 microg/kg/min) and phenylephrine (0.50+/-0.22 microg/kg/min) to increase mean arterial blood pressure by 30%.

MEASUREMENTS AND MAIN RESULTS

Data on jejunal mucosal perfusion, jejunal mucosal hematocrit, and red blood cell velocity (laser Doppler flowmetry) as well as gastric-arterial Pco2 gradient (tonometry) and splanchnic oxygen extraction were obtained before (control) and during a 30-min drug infusion period after the target mean arterial blood pressure was reached. The procedure was sequentially repeated for the second vasopressor. Both drugs induced a 40-46% increase in systemic vascular resistance with no change in cardiac index. Neither jejunal mucosal perfusion, jejunal mucosal hematocrit, red blood cell velocity, nor gastric-arterial Pco2 gradient was affected by any of the vasopressors. Splanchnic oxygen extraction increased from 38.2% to 43.1% (p<.001) with norepinephrine and from 39.3% to 47.5% (p<.001) with phenylephrine. This increase was significantly more pronounced with phenylephrine compared with norepinephrine (p<.05). Mixed venous-hepatic vein oxygen saturation gradient increased with both drugs (p<.01), and the increase was more pronounced with phenylephrine (p<.05). Splanchnic lactate extraction was not significantly affected by any of the vasopressors.

CONCLUSIONS

Phenylephrine induced a more pronounced global alpha1-mediated splanchnic vasoconstriction compared with norepinephrine. Neither of the vasoconstrictors impaired perfusion of the gastrointestinal mucosa in postcardiac surgery patients. The lack of norepinephrine-induced, alpha1-mediated impairment of gastrointestinal perfusion is not explained by a beta2-mediated counteractive vasodilation but instead by possible mucosal autoregulatory escape.

Cardiopulmonary bypass in humans--jejunal mucosal perfusion increases in parallel with well-maintained microvascular hematocrit

BACKGROUND

An imbalance between splanchnic oxygen supply and demand occurs during cardiopulmonary bypass (CPB) in man, which might disrupt the intestinal mucosal barrier function. The aim of the present study was to evaluate the effects of mild hypothermic CPB on intestinal mucosal perfusion in man undergoing cardiac surgery. Additionally we aimed to identify variables, which independently could predict changes of intestinal mucosal microcirculatory variables during CPB.

METHODS

Jejunal mucosal perfusion (JMP), jejunal mucosal hematocrit (JMHt), red blood cell (RBC) velocity and arteriolar vasomotion using endoluminal jejunal laser Doppler flow metry were studied in eight cardiac surgical patients before and during CPB at a temperature of 34 degrees C.

RESULTS

Cardiopulmonary bypass and the accompanied hemodilution (25-30%) induced a 44% increase in JMP (P < 0.05) and a 42% increase in RBC velocity (P < 0.01), with no change in JMHt. The oscillation amplitude of JMP, at a fundamental frequency of 2.8 cycles min(-1), increased with 175% (P < 0.05) during CPB. Splanchnic oxygen extraction increased by 64% during CPB (P < 0.05). Stepwise multiple regression analysis identified systemic hematocrit, arterial O2 and CO2 tension and splanchnic oxygen extraction as independent predictors of RBC velocity during CPB (R2=0.63, P < 0.001). The oscillation amplitude of JMP was predicted by RBC velocity and splanchnic oxygen extraction (R2= 0.68, P <0.0001).

CONCLUSIONS

The increase in RBC velocity and enhanced arteriolar vasomotion, as well as maintained jejunal mucosal hematocrit, are microcirculatory, compensatory mechanisms for the splanchic oxygen supply/demand mismatch seen during cardiopulmonary bypass in humans.

Effects of norepinephrine alone and norepinephrine plus dopamine on human intestinal mucosal perfusion

OBJECTIVES

To evaluate the effect of norepinephrine alone and norepinephrine combined with dopamine on jejunal mucosal perfusion, gastric-arterial pCO(2) gradient, and global splanchnic oxygen demand-supply relationship after cardiac surgery.

DESIGN

A prospective interventional study.

SETTING

A university cardiothoracic intensive care unit.

PATIENTS

Eighteen patients were studied during propofol sedation and mechanical ventilation after uncomplicated coronary artery bypass surgery.

INTERVENTIONS

After control measurements, each patient received norepinephrine (50+/-26 ng.kg.min) to increase mean arterial blood pressure by 30% followed by addition of low-dose dopamine (2.6+/-0.3 microg x kg x min). Postdrug control measurements were performed 120 min after discontinuation of the catecholamines.

MEASUREMENTS AND RESULTS

Norepinephrine induced a 32% increase in systemic vascular resistance with no change in cardiac index. Neither jejunal mucosal perfusion, assessed by laser Doppler flowmetry, nor gastric-arterial pCO(2) gradient (tonometry) was affected by norepinephrine. Splanchnic O(2)-extraction increased ( P<0.05) and this increase was positively correlated to the individual dose of norepinephrine ( r = 0.78, P<0.0001). Splanchnic lactate extraction was increased by norepinephrine ( P<0.05). None of the patients had splanchnic lactate production during norepinephrine infusion. The addition of dopamine increased cardiac index by 27% ( P<0.001) and decreased splanchnic O(2 )extraction. Dopamine increased jejunal mucosal perfusion by 32% ( P<0.001) while the gastric-arterial pCO(2) gradient remained unchanged.

CONCLUSIONS

Vasopressor therapy with norepinephrine after cardiac surgery did not jeopardize intestinal mucosal perfusion in spite of a dose-dependent increase of the global splanchnic oxygen demand-supply relationship. The addition of dopamine increased intestinal mucosal perfusion.

Jejunal mucosal perfusion is well maintained during mild hypothermic cardiopulmonary bypass in humans

In the present study, the effects of mild hypothermic (34 degrees C) cardiopulmonary bypass (CPB) on jejunal mucosal perfusion (JMP), gastric tonometry, splanchnic lactate, and oxygen extraction were studied in low-risk cardiac surgical patients (n = 10), anesthetized and managed according to clinical routine. JMP was assessed by endoluminal laser Doppler flowmetry. Patients were studied during seven 10-min measurement periods before, during, and 1 h after the end of CPB. Splanchnic oxygen extraction increased during hypothermia and particularly during rewarming and warm CPB. JMP increased during hypothermia (26%), rewarming (31%), and warm CPB (38%) and was higher 1 h after CPB (42%), compared with pre-CPB control. The gastric-arterial PCO(2) difference was slightly increased (range 0.04-2.26 kPa) during rewarming and warm CPB as well as 1 h after CPB, indicating a mismatch between gastric mucosal oxygen delivery and demand. None of the patients produced lactate during CPB. We conclude that jejunal mucosal perfusion appears well preserved during CPB and moderate (34 degrees C) hypothermia; this finding is in contrast to previous studies showing gastric mucosal hypoperfusion during CPB.

IMPLICATIONS

Jejunal mucosal perfusion increases during mild hypothermic cardiopulmonary bypass (CPB). Intestinal laser Doppler flowmetry, gastric tonometry, and measurements of splanchnic lactate extraction could not reveal a local or global splanchnic ischemia during or after CPB. A mismatch between splanchnic oxygen delivery and demand was seen, particularly during rewarming and warm CPB.

Jejunal and gastric mucosal perfusion versus splanchnic blood flow and metabolism: an observational study on postcardiac surgical patients

OBJECTIVES

To evaluate the association between changes in total splanchnic and mucosal perfusion, assessed either by gastric tonometry or jejunal laser Doppler flowmetry in postcardiac surgical patients.

DESIGN

A prospective, observational study.

SETTINGS

A general intensive care unit in a tertiary care center.

PATIENTS

Twelve, postoperative cardiac surgery patients were studied.

INTERVENTIONS

Patients were treated according to clinical routine. Total splanchnic blood flow (indocyanine green extraction), jejunal mucosal perfusion (laser Doppler flowmetry), gastric mucosal-arterial PCO2 gradients, and splanchnic lactate uptake were studied during four 30-min measurements periods, each separated by a period of 1 hr.

MEASUREMENTS AND MAIN RESULTS

There was no consistent association between either total splanchnic and local mucosal perfusion or between gastric and jejunal perfusion as assessed by two different techniques. The PCO2 gradient increased from 0.73+/-0.21 kPa to 1.15+/-0.30 kPa (p < .05), and splanchnic oxygen extraction increased from 40%+/-9% to 49%+/-14% (p < .01).

CONCLUSIONS

In this observational study on postcardiac surgical patients, local mucosal perfusion did not reflect total splanchnic blood flow and vice versa. Either changes in gastric and jejunal mucosal perfusion were different or increasing tissue metabolism was responsible for the observed lack of association between tonometry, laser Doppler flowmetry, and total splanchnic blood flow. Increasing mucosal arterial PCO2 gradient and splanchnic oxygen extraction may reflect a mismatch between splanchnic perfusion and metabolic demands.

Differential effects of dopamine, dopexamine, and dobutamine on jejunal mucosal perfusion early after cardiac surgery

OBJECTIVE

To evaluate the potential differential effects of dopamine, dopexamine, and dobutamine on jejunal mucosal perfusion, assessed by endoluminal laser Doppler flowmetry in uncomplicated postcardiac surgical patients.

DESIGN

A prospective, blinded, randomized, crossover study.

SETTING

A cardiothoracic intensive care unit in a tertiary care center.

PATIENTS

A total of ten postoperative cardiac surgical patients were studied.

INTERVENTIONS

Each patient received sequentially, randomly, and in a blinded fashion 2.7+/-0.2 microg x kg(-1) x min(-1) dopamine, 0.7+/-0.1 microg x kg(-1) x min(-1) dopexamine, and 2.7+/-0.1 microg x kg(-1) x min(-1) dobutamine. Each inotropic agent was titrated to increase cardiac output by 25% from baseline. Data on jejunal mucosal perfusion, splanchnic lactate, and oxygen extraction were obtained during a 5-min control period and a 5-min drug infusion period after the target cardiac output was reached. The procedure was sequentially repeated for each agent, and there was a 20- to 30-min washout period between each agent.

MEASUREMENTS AND MAIN RESULTS

Dopamine, dopexamine, and dobutamine increased jejunal mucosal perfusion by 27% (p < .01), 20% (p < .001), and 7% (p < .001), respectively. The increase in jejunal mucosal perfusion by dopamine and dopexamine were significantly more pronounced compared with dobutamine (p < .05 and p < .01, respectively), whereas there was no difference between dopamine and dopexamine. Splanchnic oxygen extraction decreased to the same extent with all three drugs. Splanchnic lactate extraction did not change for any of the drugs. The effects on central hemodynamics were similar for the three inotropic agents.

CONCLUSIONS

Endoluminal laser Doppler flowmetry is a new tool for the detection of perfusion changes at the local intestinal mucosal level. Dopamine, dopexamine, and dobutamine have differential effects on jejunal mucosal perfusion probably because of their different receptor stimulating properties. These findings may be of clinical importance when the therapeutic goal is to improve gut mucosal perfusion.

Metastatic complications of Staphylococcus aureus septicemia. To seek is to find

Improvement in the high mortality from Staphylococcus aureus septicemia must address the individualized treatment (surgery and/or prolonged antibiotic treatment) of metastatic complications. The aim of this study was to evaluate the results of a comprehensive diagnostic monitoring for metastatic complications in S. aureus septicemia. 68 consecutive patients with S. aureus septicemia were prospectively followed. The performance rate and results of chest X-ray, echocardiography, bone scintigraphy and leukocyte scintigraphy are described. Metastatic complications were found in 53% of the 68 patients, endocarditis in 26%. Positive findings resulted in surgical intervention in 23 patients. The total mortality defined as all deaths within 12 weeks was 24%; 81% of the deceased were > or = 60 years of age. Non-endocarditis patients with peripheral septic metastases had good prognosis. An active monitoring for metastatic complications in S. aureus septicemia is a necessary prerequisite for optimizing treatment and to improve survival rate.

Attitudes of trained Swedish lay rescuers toward CPR performance in an emergency. A survey of 1012 recently trained CPR rescuers

59 years old. Only 1% had attended the course because of their own or a relative's cardiac disease. Ninety-four per cent believed there was a minor to major risk of serious disease transmission while performing CPR. When predicting their willingness to perform CPR in six scenarios, 17% would not start CPR on a young drug addict, 7% would not perform CPR on an unkempt man, while 97% were sure about starting CPR on a relative and 91% on a known person. In four of six scenarios, respondents from rural areas were significantly more positive than respondents from metropolitan areas about starting CPR. In conclusion, readiness to perform CPR on a known person is high among trained CPR rescuers, while hesitation about performing CPR on a stranger is evident. Respondents from rural areas are more frequently positive about starting CPR than those from metropolitan areas.

Bacteriologic evidence of infection caused by coagulase-negative staphylococci in total hip replacement

Coagulase-negative staphylococci are important agents of infected hip arthroplasties, but sample contamination from the skin flora may confuse the diagnosis. Recovery of multiple identical strains has been regarded as indication of true infection. We have evaluated 29 total hip replacement operations with cultures positive for coagulase-negative staphylococci in a prospective study, 16 with > or = 3 isolates available for strain identity analysis. In 26 episodes, > or = 3 cultures were positive for coagulase-negative staphylococci, but only 19 of them had strong or intermediate clinical evidence of infection. Negative clinical evidence of infection coincided with the absence of a predominating strain according to plasmid profile analysis. A reliable identity analysis may help to rule out infection when multiple cultures are positive in patients who lack clinical evidence of infection.

Baroreceptor-mediated reduction of jejunal mucosal perfusion, evaluated with endoluminal laser Doppler flowmetry in conscious humans

Reduction of central blood volume elicits a peripheral vasoconstrictor reflex in various tissues including skin, skeletal muscle and the hepatomesenteric region. The aim of the present study was to investigate whether this reaction includes a decreased perfusion of the jejunal mucosa in man. Laser Doppler flowmetry (LDF) was used to monitor jejunal mucosal and skin perfusion simultaneously in eleven healthy volunteers. LDF recordings were performed during quiescent (phase 1) periods of the migrating motor complex. Seven subjects demonstrated cycling changes of jejunal mucosal perfusion (vasomotion). The average minimum jejunal flux value was 72 +/- 6 perfusion units. The average intraindividual coefficient of variation was 18 +/- 2%. Lower body negative pressure (LBNP) was used to elicit controlled reductions of central blood volume. LBNP of 10 mm Hg induced a 12 +/- 4% (P < 0.05) decrease in jejunal perfusion and a 43 +/- 11 (P < 0.001) decrease in cutaneous perfusion. Corresponding responses to LBNP of 20 mm Hg were 17 +/- 5% (P < 0.01) and 37 +/- 10% (P < 0.01) reductions in jejunal mucosal and skin perfusion, respectively. Cardiac index was significantly reduced by the LBNP procedure, whereas heart rate remained unchanged and blood pressure changes were minor and inconsistent. These findings indicate that the reflex vasoconstriction induced by mild central hypovolemia includes a significant reduction of jejunal mucosal perfusion in supine resting humans. This reflex may provide one mechanism for the intestinal ischemia often occurring in critically ill patients.

Cerebrospinal fluid filtration in a case of severe pneumococcal meningitis

Current therapy of bacterial meningitis includes high doses of antibiotics and, sometimes, addition of corticosteroids in order to reduce a harmful inflammatory response. The persisting high mortality and rate of sequelae, particularly regarding pneumococcal meningitis, calls for new therapeutic approaches. We report a case of a 71-year-old female with a pneumococcal meningitis treated with extra-corporeal filtration of cerebrospinal fluid (CSF) after 3 days of coma on conventional treatment. The treatment was carried out without complications and the clinical outcome was favourable. We suggest that filtration of the CSF should be considered as a tool to eliminate noxious substances playing a harmful role in deteriorating course of bacterial meningitis.

Enteric infections in the traveler: a socioeconomic perspective

Tourism is an important part of world trade. One of its side-effects is infectious diarrhea in the traveler. The community costs of traveler's diarrhea mainly relate to the loss of production covered by social insurance, which, in the Swedish example, exceeds direct medical expenses by a factor of five. The responsibility for preventive measures in charter tourism rests with the tourism-exporting countries and organizations and should constitute an important sales argument.

PCR for the diagnosis of enteroviral meningitis

A 2-step 'semi-nested' enterovirus PCR was developed and applied to CSF and serum specimens from 27 consecutive patients with aseptic meningitis. CSF and sera from 8 patients with non-enteroviral diagnoses were included as negative clinical controls. Enterovirus RNA was detected in CSF by PCR in 15 of the patients with aseptic meningitis, compared with 6 by virus culture. Acute-phase sera proved positive for enterovirus RNA in 11 patients, thus increasing the number of PCR-positive patients to 18. Convalescent-phase sera were all negative by PCR. The correlation of a positive or negative PCR result in CSF and/or serum versus combined conventional virology (serology and isolation from 1-3 sites, i.e. CSF, stool and throat) was 78%. All negative controls were negative by PCR. PCR is a reliable and sensitive diagnostic tool for the detection of enteroviral infections. Both CSF and acute-phase serum should be considered for testing.

Two-step PCR in the retrospective diagnosis of enteroviral viraemia

Enteroviral infections are potentially serious in man causing a variety of syndromes and a viraemic phase is probable in most patients. However, virological diagnosis is usually indirect by isolation of the agent from throat or stools when possible, and/or slow due to the need to titrate antibodies in paired sera. Because of its high sensitivity the polymerase chain reaction (PCR) offers the possibility of rapid detection of even low-grade viraemia. We have developed a 2-step PCR procedure adapted for enteroviruses and applied it to stored sera from patients with enteroviral meningitis. The acute sera from 7/12 patients were positive but the 4 convalescence sera tested, 2 of which had been positive at the acute phase, were negative. The assay should now be tested prospectively on serum and cerebrospinal fluid and could be developed for routine diagnosis.

Specific binding of lactoferrin to Escherichia coli isolated from human intestinal infections

The degrees of human lactoferrin (HLf) and bovine lactoferrin (BLf) binding in 169 Escherichia coli strains isolated from human intestinal infections, and in an additional 68 strains isolated from healthy individuals, were examined in a 125I-labelled protein binding assay. The binding was expressed as a percentage calculated from the total labelled ligand added to bacteria. The HLf and BLf binding to E. coli was in the range 3.7 to 73.4% and 4.8 to 61.6%, respectively. Enterotoxigenic strains demonstrated a significantly higher HLf binding (median = 19%) than enteropathogenic, enteroinvasive, enterohaemorrhagic strains or normal intestinal E. coli isolates (medians 6 to 9). Enteropathogenic strains belonging to serotypes O44 and O127 demonstrated significantly higher HLf binding compared to O26, O55, O111, O119 and O126. No significant differences in the degree of HLf or BLf binding were found between aerobactin-producing and non-producing strains. The interaction was further characterized in a high Lf-binding EPEC strain, E34663 (serotype O127). The binding was stable in the pH range 4.0 to 7.5, did not dissociate in the presence of 2M NaCl or 2M urea, and reached saturation within two h. Unlabelled HLf and BLf displaced the 125I-HLf binding to E34663 in a dose-dependent manner. Apo- and iron-saturated forms of Lf demonstrated similar binding to E34663. Among various unlabelled subepithelial matrix proteins and carbohydrates tested (in 10(4)-fold excess) only fibronectin and fibrinogen caused a moderate inhibition of 125I-HLf binding. According to Scatchard plot analysis, 5,400 HLf-binding sites/cell, with an affinity constant (Ka) of 1.4 x 10(-7) M, were estimated in strain E34663. These data establish the presence of a specific Lf-binding mechanism in E. coli.

Evaluation of coagulase-negative staphylococci in blood cultures. A prospective clinical and microbiological study

Coagulase-negative staphylococci (CNS) are the commonest microorganisms in blood cultures, and sorting out patients with CNS septicemia from sample contamination a persistent problem. We prospectively evaluated 73 patients with CNS-positive blood cultures during 1 year and analysed the corresponding 122 isolates in order to determine the rate of septicemia and define the role of microbiological markers of identity such as plasmid profile for that purpose. Three patients had true septicemia, all of them with implanted foreign devices. The plasmid analysis, being the most reliable identity marker, had its greatest implication in reducing the intermediate group of patients clinically suspected of septicemia from 12 to 4. Strict clinical criteria and serial blood cultures are most important in sorting out patients with CNS septicemia from cases of sample contamination. In high risk patients--critically ill with implanted foreign devices--plasmid analysis or other reliable markers of identity are of great additional value.

Acute diarrhoea in adults: aetiology, clinical appearance and therapeutic aspects

A prospective study of acute diarrhoea was performed during 15 months 1981/1982 and included 731 patients and 240 controls. 43% had been infected abroad. A cluster of travellers with bacterial pathogens was diagnosed in July-August. The following pathogens were found: Campylobacter (18%), enterotoxigenic E. coli (6%), Salmonella spp. (5%), rotavirus (4%), Yersinia enterocolitica (3%), Giardia lamblia (3%), Shigella spp. (2%), Clostridium difficile (2%), enteroviruses (2%) and Entamoeba histolytica (less than 1%). More than 90% of the bacterial or parasitic enteropathogens were detected in the first stool sample. Only 10% of the patients needed hospital treatment and for 97% oral fluids were sufficient. The median duration of diarrhoea was 9 days. No fatal cases occurred and only 2 cases of chronic bowel disease were detected.

Socioeconomic effects of acute diarrhoea in adults

Epidemiological features and socioeconomic importance of acute diarrhoea in adults were studied in a prospective investigation of 309 patients and 240 controls in the city of Malmö, Sweden. Data from a national survey of 6,000 individuals interviewed for gastrointestinal and other symptoms were included. The age group 20-35 years constituted half of the patients. Although 41% of all patients were travellers--and travelling is more common in young people--the age distribution was not due to travelling habits alone. A relative risk of attracting diarrhoea abroad in different geographical regions is indicated, tropical Africa and Romania having the highest risk factors. The community costs of diarrhoea depend much more on production loss by the affliction of young people than direct costs for medical care. Preventive measures would be economically rewarding.

Fusidic acid for the treatment of antibiotic-associated colitis induced by Clostridium difficile

Twenty courses of fusidic acid were given to 16 patients with antibiotic-associated colitis caused by Clostridium difficile. Fusidic acid was given in a dose of 0.5-1.5 g daily for seven to 21 days. Diarrhoea disappeared rapidly. Clinical relapse occurred after five courses and once when the patient was still on treatment. Clinical cure with persistence or reappearance of toxin occurred in four further patients. Nineteen courses of metronidazole were given to 19 patients who experienced six failures or relapses. Seven courses of vancomycin were given to five patients, three of whom had had relapse. Five patients healed without treatment. The relapses occurred only in old and prostrated patients. They often recurred several times in the same patient. 0.5 g of fusidic acid daily appears to be as effective as vancomycin and metronidazole for the treatment of C. difficile-induced colitis.

Galvanic element produced by defective electrode insulation--a possible cause of abnormal pulse generator inhibition

In patients with pacemaker, abnormal inhibition with prolongation of pacing intervals may cause alarming clinical symptoms. A case is described in which high current threshold in relation to voltage threshold indicated probability of an insulation defect with current leakage. Electrograms from the electrode disclosed false signals, which had appeared after replacement of a pulse generator six months earlier. A sharp bend of the wire in the tricuspid area was shown by X-ray and was accentuated by movements of the valve. Experimentally it was demonstrated that similar potentials, sufficient to inhibit a pulse generator, can be obtained from an electrode with defective insulation. A galvanic element forms between the metals of the electrode tip and the non-insulated cable, and potential variations are elicited by movement of the wire.

Diarrhoea in Swedish infants. Aetiology and clinical appearance

Ninety-five children with gastroenteritis admitted at the Department of Paediatrics, Malmö General Hospital, Malmö, Sweden, starting November 1978 through October 1979 were studied. Patients were examined clinically and the course of their disease was followed. Stool specimens from all patients were analysed by routine bacteriology and rotavirus identification was done by immune-electroos-mophoresis. Fifty-eight per cent of patients had rotavirus. Campylobacter was found in 6%, enteropathogenic E. coli in 2%, Yersinia enterocolitica in 2% and Salmonella in 1% of patients. Stool specimens from 53 healthy children matched for sex and age served as controls for bacterial pathogens. All were negative. Forty per cent of patients presented with a clinical dehydration, but only 11%-half of them with bacterial enteropathogens-needed i.v. therapy and 4% required antibiotic treatment. Median time for hospitalization was three days. Vomiting, fever, watery diarrhoea and initial clinical dehydration were more commonly associated with rota virus infection. Macroscopic blood in stools was restricted to patients with bacterial aetiology.

Antibiotic sensitivity of enteropathogenic Escherichia coli to mecillinam, trimethoprim-sulfamethoxazole and other antibiotics

Forty-six clinical isolates of enteropathogenic Escherichia coli (EPEC) collected in Addis Ababa, Ethiopia, 1977--1978, were tested for susceptibility to 12 different antibiotics and beta-lactamase-production. Special reference was made to mecillinam and trimethoprim-sulfamethoxazole (TMP-SMZ) that were recently shown to be effective in the treatment of severe gastroenteritis caused by EPEC. Twenty-nine of the strains were of serotype 0111:B4. Thirty of the strains were resistant to 4 antibiotics or more, most of these strains belonging to serotype 0111:B4. For mecillinam, 19 strains had minimal inhibitory concentration (MIC) less than or equal to 0.2 microgram/ml, 27 strains had MIC 0.8--3.2 microgram/ml. Regarding TMP-SMZ, 41 strains had MIC less than or equal to 1 microgram/ml, 5 strains had 2--4 microgram/ml. No strain was resistant to gentamicin or nalidixic acid. Increased production of beta-lactamase was correlated to ampicillin resistance.

Mecillinam and ampicillin separately or combined in gram-negative septicemia

Of 20 patients with gram-negative septicemia treated with mecillinam alone or in combination with ampicillin, successful therapeutic results were obtained in 16. In 11 patients treated with ampicillin alone, three failures responded successfully to a combination of mecillinam and ampicillin. Mecillinam MIC values of isolated Enterobacteriaceae were 0.05-0.4 micrograms/ml. In patients receiving 5 mg/kg mecillinam intravenously every six hours, the mean 0.5 hour concentration was 11.0 micrograms/ml and in those given 10 mg/kg 23.3 migcrograms/ml. No serious side effects were recorded. One patient on mecillinam developed an exanthema, as did three patients on combined therapy.

Antibiotics in the treatment of gastroenteritis caused by enteropathogenic Escherichia coli

The role of antibiotics in treating endemic infantile diarrhea caused by enteropathogenic Escherichia coli has not been determined. In a controlled study of 49 patients, one group received mecillinam and another group received trimethoprim-sulfamethoxazole. A third group served as control subjects. Serotype O111:B4 dominated. Treatment, as evaluated clinically on the third day, resulted in cure for 79% of those receiving mecillinam, 73% of those receiving trimethoprim-sulfamethoxazole, and 7% of the control subjects. Bacteriologic cure was confirmed in 53%, 53%, and 0, respectively. The statistically significant difference between antibiotic-treated patients and control subjects (P less than 0.001) indicated that antibiotics are an important supplement in the treatment of endemic severe diarrhea caused by enteropathogenic E. coli.

Influence of output capacitor, electrode and pulse width on power consumption in cardiac pacing

Three different types of unipolar endocardial electrodes--47 in all--were compared in regard to power consumption at stimulation threshold with six different output capacitors and seven pulse widths. Fifteen were conventional large surface electrodes (area 47 mm2); 18 were conventional small surface electrodes (area 6 mm2), and 14 had a specially designed tip with a large area but small active surface of 8 mm2. Pulse widths ranged from 0.15 to 2.0 msec and output capacitors from 1.0 to 22.0 microFarads. All in all about 2,000 measurements were performed. The average current drain to the pacemaker output stage was measured and power consumption was calculated for each electrode--pulse width--output capacitor combination. In all combinations, the two small surface electrodes consumed approximately the same amount of power and, in both cases, significantly less than the larger one. With regard to power economy at stimulation threshold, the pulse width of choice was about 0.5 msec and, furthermore, power consumption decreased with increasing capacitor size. The optimal combination was a small surface electrode, an output capacitor of 22 microF and a pulse width of 0.5 msec.