Severe heart failure in a unique case of cobalamin-C-deficiency resolved with LVAD implantation and subsequent heart transplantation.

Introduction Cobalamin c deficiency (cblC), an inborn error of vitamin B12 metabolism, is caused by mutations of the MMACHC gene. It usually leads to a multisystemic disease; 50% of all patients with cblC have various structural heart defects. Severe congestive heart failure (HF) may also occur and its prognosis is poorly documented. Case report We present the case of a young man who had been diagnosed with cblC due to C331T mutation in the MMACHC gene at the age of 3 days and had been treated with substitution therapy (OH-Cbl, mecobalamine, carnitine, betaine, and calcium folinate) since then. He had mildly impaired cognitive function; an ectopic hypophysis/pituitary insufficiency, with adequate hormone replacement therapy; obstructive sleep apnea syndrome, treated with CPAP, bronchial asthma, and obesity (BMI of 30). The liver and kidney functions were normal. He developed severe dilated cardiomyopathy and HF at the age of 12y. With medical treatment, his condition improved and he was stable (NYHA class II) for several years. Six years later, his status deteriorated rapidly, as he developed advanced HF, INTERMACS 3. The cardiac ultrasound revealed dilated ventricles with severely depressed ejection fraction (EF), increased filling pressures, and pulmonary hypertension (sPAP 60 mmHg). Cardiac MRI showed extremely dilated chambers (LVedv 609 mL, RVedv 398 mL) with pronounced non-compaction, and a left ventricle EF of 13%. A primary prophylactic ICD and a left ventricular assist device (LVAD/HM3) were implanted, and the patient was subsequently listed for heart transplantation (HTx). After 25 months on the waiting list, he underwent an uncomplicated HTx. However postoperatively, he got two episodes of cardiac tamponade, as well as mediastinitis, treated with antibiotics and vaccum assisted closure. He developed severe kidney failure, which fully recovered after two months, and was treated successfully for an early moderate allograft rejection (ISHT 2). At the latest outward visit, twelve months after HTx, the patient was doing excellent. Summary To the best of our knowledge, this is the first ever reported case of a patient with CblC undergoing an LVAD implantation and subsequently a HTx. Although both interventions were complicated with bleeding events, this seems to be a treatment option for advanced HF in patients with CblC.

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.

Dextran-based priming solution during cardiopulmonary bypass attenuates renal tubular injury-A secondary analysis of randomized controlled trial in adult cardiac surgery patients.

BACKGROUND: Acute kidney injury (AKI) is a well-known complication after cardiac surgery and cardiopulmonary bypass (CPB). In the present secondary analysis of a blinded randomized controlled trial, we evaluated the effects of a colloid-based versus a conventional crystalloid-based prime on tubular injury and postoperative renal function in patients undergoing cardiac surgery with CPB. METHODS: Eighty-four adult patients undergoing cardiac surgery with CPB were randomized to receive either a crystalloid- or colloid- (dextran 40) based CPB priming solution. The crystalloid solution was based on Ringer-Acetate plus mannitol. The tubular injury biomarker, N-acetyl-b-D-glucosaminidase (NAG), serum creatinine and diuresis were measured before, during and after CPB. The incidence of AKI was assessed according to the KDIGO criteria. RESULTS: The urinary-NAG/urinary-creatinine ratio rose in both groups during and after CPB, with a more pronounced increase in the crystalloid group (p = .038). One hour after CPB, the urinary-NAG/urinary-creatinine ratio was 88% higher in the crystalloid group (4.7 ± 6.3 vs. 2.5 ± 2.7, p = .045). Patients that received the dextran 40-based priming solution had a significantly lower intraoperative diuresis (p < .001) compared to the crystalloid group. The incidence of AKI was 18% in the colloid and 22% in the crystalloid group (p = .66). Postoperative serum creatinine did not differ between groups. CONCLUSIONS: In patients undergoing cardiac surgery with CPB, colloid-based priming solution (dextran 40) induced less renal tubular injury compared to a crystalloid-based priming solution. Whether a colloid-based priming solution will improve renal outcome in high-risk cardiac surgery, or not, needs to be evaluated in future studies on higher risk cardiac surgery patients.

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.

Dextran- Versus Crystalloid-Based Prime in Cardiac Surgery: A Prospective Randomized Pilot Study.

BACKGROUND: The optimum priming fluid for the cardiopulmonary bypass (CPB) circuit is still debated. We compared a new hyperoncotic priming solution containing dextran 40, which has an electrolyte composition that mimics extracellular fluid, with a standard crystalloid-based prime. METHODS: Eighty cardiac surgery patients were included in this double-blind, randomized, single-center study. Patients were randomized to either a dextran-based prime or a crystalloid prime containing Ringer's acetate and mannitol. The primary end point was colloid oncotic pressure in serum during CPB. Secondary end points included fluid balance, bleeding and transfusion requirements, pulmonary function, hemolysis, systemic inflammation, and markers of renal, hepatic, myocardial, and brain injury. Blood samples were collected before, during, and after CPB. RESULTS: Colloid oncotic pressure was higher in the dextran group than in the crystalloid prime group during CPB (18.8 ± 2.9 versus 16.4 ± 2.9 mm Hg; P < .001) and 10 minutes after CPB (19.2 ± 2.7 versus 16.8 ± 2.9 mm Hg; P < .001). Patients in the dextran group required less intravenous fluid during CPB (1090 ± 499 versus 1437 ± 543 mL; P = .004) and net fluid balance was less positive 12 hours after surgery (1431 ± 741 versus 1901 ± 922 mL; P = .014). Plasma-free hemoglobin was significantly lower in the dextran group 2 hours after CPB (0.18 ± 0.11 versus 0.41 ± 0.33; P = .001). There were no significant differences in bleeding, transfusion requirements, organ function, systemic inflammation, or brain and myocardial injury markers between groups at any time point. CONCLUSIONS: Our results suggest that a hyperoncotic dextran-based priming solution preserves intraoperative colloid oncotic pressure compared with crystalloid prime. Larger studies with clinically valid end points are necessary to evaluate hyperoncotic prime solutions further.

The poorly explored impact of uncontrolled asthma.

The goal of asthma management is to achieve disease control; however, despite the availability of effective and safe medications, for many patients asthma remains uncontrolled. One reason for this is the fear of long-term side effects from the regular use of inhaled corticosteroids (ICSs). Adverse effects of poorly controlled asthma (for example, obesity, pneumonia, and risks to the fetus) can be perceived as side effects of ICSs. Poorly controlled asthma adversely affects children's cardiovascular fitness, while children with well-controlled asthma perform at the same level as their peers. Children with uncontrolled asthma also have a higher frequency of obesity than children with controlled asthma. Stress can affect asthma control, and children with poorly controlled asthma are more likely to have learning disabilities compared with those with good control. In adults, focused attention and concentration are negatively affected in patients with untreated asthma, and patients with asthma are at greater risk for depression. Also, poorly controlled asthma increases the risks of severe asthma exacerbations following upper respiratory and pneumococcal pulmonary infections. ICSs used to improve asthma control have been demonstrated to improve all of these outcomes. Lastly, the risks of uncontrolled asthma during pregnancy are substantially greater than the risks of recommended asthma medications. Treatments to maintain asthma control are the best approach to optimize maternal and fetal health in the pregnancies of women with asthma. The maintenance of asthma control has significant advantages to patients and greatly outweighs the potential risks of treatment side effects.

Target Temperature Management after out-of-hospital cardiac arrest--a randomized, parallel-group, assessor-blinded clinical trial--rationale and design.

BACKGROUND: Experimental animal studies and previous randomized trials suggest an improvement in mortality and neurologic function with induced hypothermia after cardiac arrest. International guidelines advocate the use of a target temperature management of 32°C to 34°C for 12 to 24 hours after resuscitation from out-of-hospital cardiac arrest. A systematic review indicates that the evidence for recommending this intervention is inconclusive, and the GRADE level of evidence is low. Previous trials were small, with high risk of bias, evaluated select populations, and did not treat hyperthermia in the control groups. The optimal target temperature management strategy is not known. METHODS: The TTM trial is an investigator-initiated, international, randomized, parallel-group, and assessor-blinded clinical trial designed to enroll at least 850 adult, unconscious patients resuscitated after out-of-hospital cardiac arrest of a presumed cardiac cause. The patients will be randomized to a target temperature management of either 33°C or 36°C after return of spontaneous circulation. In both groups, the intervention will last 36 hours. The primary outcome is all-cause mortality at maximal follow-up. The main secondary outcomes are the composite outcome of all-cause mortality and poor neurologic function (cerebral performance categories 3 and 4) at hospital discharge and at 180 days, cognitive status and quality of life at 180 days, assessment of safety and harm. DISCUSSION: The TTM trial will investigate potential benefit and harm of 2 target temperature strategies, both avoiding hyperthermia in a large proportion of the out-of-hospital cardiac arrest population.

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.

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.

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.

Comparable long-term safety and efficacy of a novel budesonide/formoterol pressurized metered-dose inhaler versus budesonide/formoterol Turbuhaler in adolescents and adults with asthma.

Budesonide/formoterol in one inhaler is an established therapy for asthma and chronic obstructive pulmonary disease. The long-term safety and efficacy profile of a novel hydrofluoroalkane (HFA) pressurized metered-dose inhaler (pMDI) formulation of budesonide/formoterol was compared with that of budesonide/formoterol in a dry powder inhaler (DPI; Turbuhaler). This multinational, 52-week, randomized, open, parallel-group study included patients aged > or = 12 years with asthma who had a forced expiratory volume in 1s (FEV1)> or = 50% of predicted normal; all patients used inhaled corticosteroids (400-1200 microg/day) and needed additional short-acting beta 2-agonist therapy. Patients were randomized to receive budesonide/formoterol pMDI or DPI 160/4.5 microg, two inhalations twice daily. Safety endpoints included assessment of adverse events and laboratory parameters. Efficacy endpoints included change from baseline in FEV1 and time to first severe asthma exacerbation. Overall, 673 patients (446pMDI, 227DPI) were included. There were no clinically significant differences between treatment groups in the nature, incidence or severity of adverse events or laboratory parameters. The number of patients experiencing adverse events was comparable in the pMDI (332/446 [74%]) and DPI (175/227 [77%]) groups; the most commonly reported adverse event was upper respiratory tract infection. The proportion of patients discontinuing as a result of adverse events was low in both groups (pMDI 12/446 [3%], DPI 2/227 [1%]). Lung function was improved to a similar extent in both groups and there was no detectable difference in time to first severe asthma exacerbation. The novel HFA pMDI formulation of budesonide/formoterol is an equally well tolerated and effective treatment for adults and adolescents with asthma as the budesonide/formoterol DPI.

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.

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.

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.