The early prediction of mortality in acute cholecystitis: Temperature, Neutrophils and Multiple organ failure (TNM) score.

OBJECTIVE: Acute Cholecystitis (AC) accounts for a significant proportion of patients presenting to the Emergency Department with abdominal pain. We suggest grading the severity of AC with a simple system: TNM, an acronym borrowed by cancer staging where T indicated Temperature, N neutrophils and M Multiple organ failure. This retrospective-prospective observational study evaluates the predictive value of TNM score on mortality of patients with AC. PATIENTS AND METHODS: TNM was developed in a training cohort of 178 patients with AC who underwent cholecystectomy from February 2005 to December 2012 (retrospectives data). To verify the prognostic value of TNM score, we prospectively recruited 172 patients who were consecutively included and treated from January 2013 to July 2020 as the validation cohort. After defining the categories T, N and M, patients were grouped in stages. The variables analyzed were age, sex, American Society of Anesthesiologists (ASA) score, blood transfusion, temperature, neutrophils count, preoperative organ failure, immune-compromised status, stage. RESULTS: In the training cohort TNM staging was: none patient at stage 0; 6 patients at stage I; 71 patients at stage II; 71 patients at stage III; 30 patients at stage IV. Death occurred in 51 patients. ASA score, neutrophils count, preoperative organ failure, stage III-IV emerged as statistically significant different prognostic factors. ASA score (III-IV) and stage (III-IV) were significant independent predictors of post-operative mortality in multivariate analysis. Comparable results were observed in the validation cohort. CONCLUSIONS: TNM classification is very easy to use; it helps to define the mortality risk and it is useful to objectively compare patients with AC.

[Exanthemic diseases (measles, chickenpox, rubella and parotitis). Focus on screening and health surveillance of health workers: results and perspectives of a multicenter working group]. / Le malattie esantematiche (Morbillo, Varicella, Rosolia e Parotite). Focus su screening e sorveglianza sanitaria dei lavoratori della sanità: risultati e prospettive di un gruppo di lavoro multicentrico.

BACKGROUND: Nosocomial transmission of varicella-zoster virus, certain paramixovirus and rubivirus might pose a risk of morbidity for varicella (V), rubella (R), mumps (Mu) and measles (Me) in health care workers (HCW), patients and coworkers. International literature and European legislation recommend preventive interventions to minimize the risk. METHODS: A literature review and a seroprevalence study were carried out in 9 hospitals located in north and central Italy, in order to evaluate risk assessment, health surveillance and fitness for work of HCW exposed to V, R, Mu and Me. Antibodies (Ab) against V, R, Mu and Me were determined. For a subgroup of 4 hospitals; sociodemographic, occupational data and sera were collected and analyzed. RESULTS: About 36000 tests on about 9000 HCW were analyzed. Differences in seroprevalence ratios (V 85.7-95.1%, R 47-96.8%, Me 71.4-97.8%, Mu 52.5-87.6%) were detected. In a subgroup, a relevant number of non immune HCW was also found among women infertile age and areas at higher risk. Statistically significant differences were detected only for selected variables and viruses. DISCUSSION AND CONCLUSIONS: Data of multicenter study confirm literature evidences and allow to define good medical practices for manage and minimize the risk of nosocomial transmission of V, R, Me and Mu. Recommendation are issued about serologic screening on HCW exposed to all 4 viruses thorough the modern analytical techniques, in order to assess risk on individual a group basis and to select priorities for intervention. Vaccination should be prescribed for those HCW non immune, selecting areas and HCW according to priorities.

Platelet activation and cytokine production during hypothermic cardiopulmonary bypass--a possible correlation?

Cardiopulmonary bypass (CPB) is associated with impaired platelet function and a systemic inflammatory response. The present study was designed to evaluate whether any correlation between platelet activation and inflammatory response during CPB exists. The results obtained from 8 patients undergoing hypothermic CPB for cardiac surgery showed the occurrence of a moderate degree of platelet activation during CPB, demonstrated by an increase of platelet CD62P expression in correlation with an increase of beta-thromboglobulin levels, with a concomitant decrease of in vitro platelet response. Plasma IL-1beta levels significantly increased during CPB, with a peak between 1 and 4 h after CPB. Similarly, IL-6 levels were elevated 30 min from CPB starting, peaked at 4 h, and remained elevated after 24 h. A direct correlation was found between plasma IL-1beta and IL-6 levels. A significant correlation between plasma IL-1beta and beta-thromboglobulin levels was also found. In turn, plasma beta-thromboglobulin levels correlated with CD62P expression on activated platelets. An inverse correlation was found between in vitro platelet aggregation and plasma IL-1beta or IL-6 levels. From the present results it may be speculated that platelet activation during CPB may contribute, through the release of IL-1beta, to activation of endothelial cells and subsequent release of other cytokines with chemotactic and pro-inflammatory properties, thus playing an important role in the inflammatory response associated with CPB.

Prospective surveillance applying the national nosocomial infection surveillance methods in a Brazilian pediatric public hospital.

BACKGROUND: A hospital-wide, traditional prospective surveillance for nosocomial infections was commenced in 1992 in Centro Geral de Pediatria in Minas Gerais, Brazil, to describe the epidemiology of nosocomial infection in this pediatric hospital and to implement cross-infection prevention and control policies. METHODS: We performed a prospective cohort nosocomial infection surveillance of all patients receiving acute care according to the hospital-wide and intensive care unit components of the National Nosocomial Infections Surveillance System from January 1993 to December 1997 (14,892 discharges; 131,764 patient-days). The Centers for Disease Control and Prevention (Atlanta) 1988-definitions and the Brazilian Ministry of Health-Legislation 930 (1992) were used. RESULTS: The average overall nosocomial infection rate per 1000 patient-days was 8.9 in units 2 and 3 and 16.4 in the pediatric intensive care unit. Over time, the overall hospital infection rate decreased from 16.6 nosocomial infections per 1000 patient-days in 1993 to 7.0 in 1997 (P <.05). We believe this can be attributed to interventions and data reporting during the period. The five most frequent sites of infections were eye-ear-nose-throat (38%), skin (22%), pneumonia (12%), soft tissue (5%) and laboratory-confirmed bloodstream infection (4%). In the pediatric intensive care unit, the most frequent nosocomial infection sites were pneumonia related to mechanical ventilators (22%), with rates ranging from 0 to 42 per 1000 ventilator-days; and sepsis related to central lines (11%), with rates ranging from 0 to 32 per 1000 central line-days. CONCLUSIONS: Describing the epidemiology of nosocomial infections in this hospital enabled us to establish infection occurrence, distribution, and expected incidence, as well as to recognize trends and keep track of possible outbreaks. The knowledge acquired through this surveillance allowed us to target more specific and continuous quality improvement projects, to upgrade health care quality in pediatric public hospitals in Brazil, and to implement preventive strategies. Methods from the National Nosocomial Infections Surveillance System can be successfully applied in pediatric public hospitals in Brazil.

Relationship between low lead exposure and somatic growth in adolescents.

The possible effects of moderate lead exposure on human growth and development are not well defined. This study was carried out in order to evaluate the relationship between somatic growth and lead exposure. 418 subjects (202 males and 216 females) aged 11-13 years in good health and living in an area of the northern region of Italy were submitted to the following determinations: blood lead levels (PbB), serum concentrations of gonadotropins (LH, FSH) and sex-steroid hormones (DHA-S, T, E2) and anthropometric measurements (stature and weight). The mean blood levels were 85.39 and 70.08 micrograms/1, respectively, for males and females. Significant and negative relationships were found between blood lead levels and stature in 13 years old males and 12 years old females (p = 0.009 and p = 0.006, respectively). Negative relationships between lead in blood and LH and FSH were found only in males with lead levels higher than 90 micrograms/1. Our findings seem to suggest that even for low lead exposure this metal may affect stature growth and gonadotropins levels.

[The effect of GH on erythropoiesis in vivo]. / Effetto, in vivo, del GH sull'eritropoiesi.

It has been demonstrated that the direct and/or indirect stimulation of hematopoiesis is one of the effects of the growth hormone (GH) in vitro. In order to study the effect of GH on erythropoiesis in vivo, the variation of hemochrome in a group of 8 subjects with GH deficiency (GHD) were monitored during a substitutive therapy with biosynthetic GH (rhGH) at dose of 0.4 U/kg/week. Hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), number of red blood cells (RBC) were analysed in all subjects at the beginning and after 9 months of treatment. The effectiveness of therapy was demonstrated by statistically significant variations in height, height SDS, growth velocity, serum levels of IGF-I. After 9 months of rhGH therapy, a significant increase was observed in all values considered with exception of MCV. In conclusion Gh would appear to stimulate erythropoiesis, directly or indirectly, and these results would appear to indicate an in vivo confirmation.

[The TRH test in Turner syndrome]. / TRH-test nella sindrome di Turner.

In order to evaluate the functionality of the hypothalamic-hypophyseal-thyroid axis in Turner's syndrome (TS), 27 subjects, aged between 5.1 and 16.1 years old, were studied, 14 of whom were karyotype 45,XO and 13 affected by mosaicism. The TRH test (200 mcg i.v.) was performed in all subjects using a single bolus. TRH titers were assayed in serum samples collected at 0, 15, 30, 60 and 90 minutes, and anti-microsome and anti-thyroglobulin, T4 and T3, were assayed in the basal sample; the latter were also assayed in the blood sample collected at 120 minutes. These results were compared with those obtained using the same test in a group of age- and sex-matched controls. Anti-thyroid antibodies and basal levels of T3 and T4 were within the norm in 26 subjects; a high basal value of TSH was only found in one patient with chromosomic mosaicism with an elevated response to TRH and a high titer of anti-microsomic antibodies. Apart from this no statistically significant differences were found in patients compared to control subjects in relation to TSH values at all stages of the test and between the two groups of TS; no significant results were found in the comparison between the areas below the curves (AUC). On the basis of these results the Authors conclude that it is not possible to reveal alterations in thyroid function attributable to hypothalamic and hypophyseal anomalies in this group of patients either with karyotype 45,XO and mosaicism.

Relationship between zinc in serum and hair and some hormones during sexual maturation in humans.

We have measured the levels of zinc in serum (Zn-S) and in hair (Zn-H) in 391 adolescents, in good health, aged between 11 and 14 years. To evaluate the relationship between zinc status and sexual maturation we have analyzed, in the same subjects, the serum concentrations of the following hormones: luteinizing hormone (LH), follicle stimulating hormone (FSH), dehydroepiandrosterone-sulphate (DHA-S), testosterone (T) and estradiol (E2). No significant relationship between zinc in the biological samples and the hormones measured in all subjects was observed; only in prepuberal females was a positive correlation found between Zn-S and E2. A significant relationship between Zn-S and LH was observed only for males with short stature or low weight (less than 25th percentile) (r = 0.359, p = 0.010; r = 0.47, p = 0.008, respectively). When prepuberal males with short stature were considered, a significant association between Zn-S and T appeared (r = 0.399, p = 0.006). In females with short stature (less than 25th percentile), partial correlation coefficients showed a significant association between FSH and zinc in hair (r = 0.435, p = 0.004), while in girls with low weight, FSH appeared positively related to zinc in hair (r = 0.470, p = 0.003) and negatively related to zinc in serum (r = -0.320, p = 0.050). Our results suggest that zinc plays an important role in the metabolism of hormones linked to sexual maturation.

Left ventricular thrombosis after blunt chest trauma.

A 22-year-old man was admitted to our observation with left ventricular thrombus arising after blunt chest trauma occurring during a ski accident one year before. None was obtained from a review of instrumental and laboratory data at trauma time. Transesophageal echocardiography showed an intraventricular thrombus and severe hypokinesia at the apex. Standard cardiac surgery procedure was performed and postoperative period was uneventful. Echocardiography controls at 6/12 months showed a normal apex kinesia. This case shows the importance of hospitalization, hemodynamics monitorization and late serial echocardiographic controls for timely diagnosis and management of myocardial contusion and consecutive ventricular thrombus formation to prevent life-threatening complications.

Factors influencing immediate and long-term results after button's technique.

BACKGROUND: Aim of this study was to evaluate the factors influencing immediate and long-term results in patients undergoing aortic root replacement with a composite graft. METHODS: Between January 1989 and February 1999, 105 patients (83 males, 22 females) who underwent Bentall technique were studied. Preoperative diagnosis was annulo-aortic ectasia in 54, aortic dissection in 27, atherosclerotic aneurysm in 21, and aortitis in 3 cases. Seventeen patients were affected by Marfan's syndrome. All cases, elective, urgent, and emergency were included. Button technique was performed and the associated surgical procedures were coronary artery bypass grafting in 21, total aortic arch replacement in 15, proximal hemi arch in 5, and mitral valve replacement in 5 cases. RESULTS: The overall hospital mortality rate was 7.6% (n=8). Univariate analysis using chi(2) and/or two-sample "t"-test showed that dissection, aortitis, aneurysm rupture into-pleura or pericardium, emergency status, redo, prolonged pump times and circulatory arrest, were predictors influencing in-hospital mortality. Coagulopathy, low cardiac output, stroke, perioperative myocardial infarction, surgical bleeding leading to reoperation, were significantly related to in-hospital mortality (by correlation analysis). A multivariate analysis showed that, emergency status (p=0.027), aortic dissection (p=0.029), perioperative myocardial infarction (p=0.0021), reoperation for bleeding (p=0.0023), and pump time >180 min (p=0.011), were significant. The actuarial survival rate at 10 years follow-up was 84.7%. There were 8 late deaths. The Kaplan-Meier showed significant differences when considering dissection vs non-dissection (p=0.018), but did not reach significance in Marfan vs non-Marfan groups (p=0.83). NYHA class IV (p=0.052), previous cardiac surgery procedure (p=0.041), concomitant CABG (p=0.021), total aortic arch reconstruction (p=0.001), and mitral valve replacement (p=0.016), were identified as significant by Log Rank test. CONCLUSIONS: The Bentall procedure for aortic root replacement is safe and durable; in hospital mortality in elective status it was 1.28%; early and long-term mortality higher in patients with acute dissection. Six late deaths were procedures related. Sixty-six patients (76.4%) were in NYHA I class at follow-up. The incidence of late outcomes, thromboembolism (1.03%), graft infection (2.06%), pseudoaneurysm (0%), reoperation in ascending aorta or aortic valve (3.1%), operations on the remaining aorta (6.7%), and hemorrhage due to anticoagulant therapy (1.03%), are very low.

Lethal effect of oxamniquine and praziquantel on mice experimentally infected with Schistosoma mansoni.

Lethality caused by administration of oxamniquine and praziquantel to mice infected with Schistosoma mansoni, and their respective controls (uninfected), has been studied. As the results indicate, the infected animals clearly showed higher mortality rates when praziquantel was used. Surprisingly, it may be noted that exactly the contrary occurs in relation to the use of oxamniquine, inasmuch as marked higher mortality rates were seen in the control animals (uninfected). These observations lead to the conclusion that further toxicological studies of antischistosomal drugs using. S. mansoni infected animals are needed.

[Adhesive peritonitis caused by a foreign body. A case report]. / Peritoniti plastiche da corpo estraneo. Caso clinico.

After investigation of the international literature on this subject, the authors describe a case report of adhesive-stenotic and retractile peritonitis, very likely caused bt a foreign body reaction (surgical stitches, gloves, rice powder, etc.?). This case-report is interesting both to remember the existence of this pathology and to limit its iatrogenic development. In conclusion, it is advisable to wash surgical gloves with sterile solutions and to limit enlarged bowel resections mostly in young people.

[The prevalence of antibodies against hepatitis B abs c virus in odontology students]. / Prevalencia de anticuerpos contra los virus de hepatitis B y C en estudiantes de odontología.

UNLABELLED: It is accepted that the practice of odontology implies a risk of BBV and HCV transmission but the study of does not. This work tries to determine the prevalence of HBv Ac and HCV Ac (by ELISA) in odontology students and whether there is any relation to the year of study and/or the presence of other risk factors. 188 students in their last three years of studies were investigated, all the participants filled out a clinical epidemiological form. 89 women (47.3%) and 99 men (52.7%), x age was 24.8. 50 (26.7%) had other risk factors. 160 (85.1%) fulfilled biosecurity norms and 40 (21.2%) had a labour accident. RESULTS: None of the analyzed sera were positive for HCV Ac (0%) and 1 was positive for HbcAc. CONCLUSION: The prevalence of HBv Ac and HCV Ac is extremely low with no relation to the year of study or any other risk factors.

[Sexual transmission of Hepatitis C virus]. / Transmisiòn sexual del virus de Hepatitis C.

Fifty heterosexual partners out of 50 patients (index cases) without confirmed or probable risk factors of parenteral transmission by HCV were studied from 1/1997 to 1/2001. The index cases were HCV Ab (+) (EIA 3rd Abbott and PCR + by RT-nested PCR). The couples with probable or confirmed risk factors of parenteral transmission were strictly excluded. No case of HCV infection was found, suggesting that sexual via wouldn't be a direct transmission of HCV.

Herpes simplex pneumonia in a heart transplant recipient.

An unusual case of Herpes simplex virus (HSV) pneumonia in a heart transplant recipient receiving chronic immunosuppressive therapy is reported. This infection presented an indolent course manifested by a chronic left pulmonary infiltrate unresponsive to antibiotic therapy and mild hypoxemia. Death eventually occurred as a consequence of an other infectious complication of the postoperative period. The HSV etiology of the necrotizing pneumonia observed at autopsy was established on the basis of histologic findings.

[Physical growth of school-children in Trent. II. Anthropometric standards and auxological evaluation of pupils at the Elementary School]. / Ricerche sull'accrescimento somatico degli scolari Trentini. Nota II: Gli standards antropometrici e la valutazione auxologica degli alunni di Scuola Elementare.

The purpose of this research was to make an auxological study of the child population in Trento. The study was carried out in three stages: in the first stage standards were established for height and weight, i.e. "anthropometric models" to be used as a reference in the subsequent assessment of children from Trento using an auxological method; during the second stage the most suitable auxological method was selected and the levels of normality, paranormality and extranormality of the anthropomorphic features were calculated; in the third stage, the above-mentioned auxological method was used to assess the growth in height and weight of the individual subjects, taking into consideration the frequency and type of auxopathies in the Trento child population. As regards the first stage of the study, after measuring the height and weight of almost all the Trento children between the ages of 6-11, the average values were calculated and the relative standard deviations of height and weight at the different ages and the weight as compared to the different heights considered. The "experimental curves" obtained were then smoothed by calculating the equations of the technical development curves of the characters examined with the best fit procedure. The smoothed values are shown in Tables 2 and 4 and the corresponding curves are given in the graphs 1-6 (median curves with a dotted line). An examination of the data in Table 2 reveals that between 6 and 10 years, males surpass the females in height and in weight, whereas, starting from 10 years and 4 months, the mean height-weight values become greater in the females due to the earlier prepuberal-puberal auxological thrust which occurs in females. After the age of 13, as can be seen in similar auxological studies recently carried out by us in Trento adolescents aged 11-14 (Tonelli et al., 1988), when the auxological thrust also takes place in males, the height of the latter regains supremacy. The mean height and weight values measured by us in 1985 in Trento school-children aged between 6-11 was then compared with those found in their peers almost twenty years earlier (1966-67) by Bergamo et al. (1968), the increases in these features during the period considered was also calculated. This comparison revealed that during the aforementioned period there was a clear increase in somatic dimensions of Trento children at all the ages examined, which varied from approximately 37 cm for height to approximately 1.5-4 kg for weight.(ABSTRACT TRUNCATED AT 400 WORDS)

[Laparoscopic or open appendectomy. Critical review of the literature and personal experience]. / Appendicectomia laparoscopica o a cielo aperto. Revisione critica della letteratura ed esperienza personale.

UNLABELLED: In the era of video-laparoscopic surgery there are a lot of surgeons that still continue to perform open appendectomy. This choice is the consequence of the good results of open appendectomy (clinical, cosmetic, hospital stays and hospital costs). Published trials on laparoscopic appendectomy don't show that it is superior to the open approach. The aim of this study is to critically review the literature on laparoscopic and traditional appendectomies and to report a clinical experience on 86 consecutive patients that underwent open appendectomy. PATIENTS AND METHODS: From September 2000 to March 2001, in the Department of Emergency Surgery of Villa Scassi Hospital in Genoa, 86 patients underwent open appendectomy (32 men; mean age 29.8 years; range 15-54 years/54 women; mean age 22.4 years; range 13-80 years). All the patients underwent blood examinations, abdomino-pelvic ultrasonographys and the women gynecological evaluation. The Authors used, almost always, the Stropeni way of access (cutaneous Mac Burney and right para-rectal incision of the muscles). Discharge has been done as soon as possible. Removed appendices were submitted to histological examination and were classified as normal or pathologic according to the severity of the lesion. Review of articles has been done on Medline. RESULTS: Suspected appendicitis have been confirmed by histological examination that documented 1 normal appendix, 7 chronic appendicitis, 45 acute catharralis, 22 acute suppurative and 11 gangrenous or perforated appendicitis. The specificity of open appendectomy has been 97.6% (100% for men). Post-operative complications were: 2 wound infections and 1 recurrence of an abscess (2.58%). Open appendectomy did carry an hospital bill of 2,500,000 IT liras (1,200 USA dollars) for non complicated appendicitis and 2,000 USA dollars for perforated appendicitis. The early discharge allowed us to spend 119 millions IT liras less in 7 months (99,600 USA dollars in a year). DISCUSSION: The role of laparoscopic appendectomy isn't still established. After a critical review of the literature we can suggest that: 1) laparoscopic appendectomy increase operative time (63 vs 43 minutes: p < 0.0001); 2) laparoscopic approach can reduce the length of post-operative stay in hospital; 3) hospital bill is strongly reduced by open appendectomy (4,274 vs 7,923 USA dollars). On our experience the cost of the hospital for uncomplicated appendicitis is 2,500,000 IT liras (1,200 USA dollars). Otherwise it has been suggested that laparoscopic appendectomy has a better diagnostic accuracy respect to open appendectomy. Some Authors report a percentage of "negative" appendices of 16-50%. In Authors experience the percentage of "negative" appendices is 1.3% and so the diagnostic accuracy is 96% in women and 100% in men, probably because we systematically performed a preoperative abdomino-pelvic ultrasonography and, for the women, a gynecological evaluation. In conclusion, laparoscopic appendectomy should be done in case of suspected appendicitis in women. In the other cases, when there is a strong clinical suspect of appendicitis and, in particular, in case of suppurative appendicitis, the Authors recommend to perform an open appendectomy using the Stropeni approach. In case of perforated appendicitis with abdominal abscess they recommend to perform an open appendectomy using the right para-rectal approach or the median umbilical-pubis approach.

Network meta-analysis on the comparative effectiveness and safety of transcatheter aortic valve implantation with CoreValve or Sapien devices versus surgical replacement.

INTRODUCTION: Surgical replacement for aortic stenosis is fraught with complications in high-risk patients. Transcatheter techniques may offer a minimally invasive solution, but their comparative effectiveness and safety is uncertain. We performed a network meta-analysis on this topic. METHODS: Randomized trials on transcatheter aortic valve replacement vs surgery were searched. The primary outcome was all cause death. Risk estimates were obtained with Bayesian network meta-analytic methods. RESULTS: Four trials with 1,805 patients were included. After a median of 8 months, risk of death and myocardial infarction was not different when comparing surgery versus transcatheter procedures, irrespective of device or access. Conversely, surgery was associated with higher rates of major bleeding (odds ratio vs CoreValve=3.03 [95% credible interval: 2.23-4.17]; odds ratio vs transfemoral Sapien =1.82 [1.21-2.70]; odds ratio vs transapical Sapien =2.08 [1.20-3.70]), and acute kidney injury (odds ratio vs CoreValve =2.08 [1.33-3.32]; odds ratio vs transapical Sapien =2.78 [2.21-99.80]), but lower rates of pacemaker implantation (odds ratio vs CoreValve =0.41 [0.28-0.59]), and moderate or severe aortic regurgitation (odds ratio vs CoreValve =0.06 [0.02-0.27]; odds ratio vs Sapien=0.17 [0.02-0.76]). Strokes were less frequent with CoreValve than with transfemoral Sapien (odds ratio =0.32 [0.13-0.73]) or transapical Sapien (odds ratio =0.33 [0.10-0.93]), whereas pacemaker implantation was more common with CoreValve (odds ratio vs surgery =2.46 [1.69-3.61]; odds ratio vs transfemoral Sapien =2.22 [1.27-3.85]). CONCLUSIONS: Survival after transcatheter or surgical aortic valve replacement is similar, but there might be differences in the individual safety and effectiveness profile between the treatment strategies and the individual devices used in transcatheter aortic valve implantation.

In vivo effects on human skeletal muscle oxygen delivery and metabolism of cardiopulmonary bypass and perioperative hemodilution.

PURPOSE: To investigate the in vivo effects of cardiopulmonary bypass (CPB) and perioperative hemodilution on human skeletal muscle oxygen delivery and metabolism and to determine the dilution state at which these effects arise. METHODS: We conducted this observational study in adult patients undergoing CPB surgery. Microcirculatory data were obtained by near-infrared spectroscopy from the brachioradial muscle in 20 consecutive patients undergoing hemodilution for CPB. Outcome variables included tissue oxy- and deoxyhemoglobin concentration ([HbO(2)], [HHb]), oxygen content, blood flow, oxygen delivery, and oxygen consumption. RESULTS: Although CPB left tissue blood flow and oxygen delivery unchanged, both microcirculatory variables correlated significantly and inversely with hematocrit (Hct) (r = -0.39, p < 0.001; r = -0.50, p < 0.001). CPB also left muscle oxygen consumption (mVO(2)) unchanged and this variable correlated with the tissue hemoglobin concentration and tissue oxygen delivery (r = 0.40, p = 0.001; r = 0.35, p = 0.005). During CPB most of the systemic cardiovascular variables remained unchanged. Conversely at Hct lower than 30%, mean arterial pressure and pH decreased and lactate values increased twofold, whereas microvascular blood volume and oxygen delivery increased. At Hct lower than 20% blood flow and oxygen delivery increased, whereas hemoglobin and oxygen content variables decreased. CONCLUSIONS: CPB leaves skeletal muscle oxygen delivery and metabolism as measured by near-infrared spectroscopy unchanged. The only factor that correlates directly with the oxygen content variables and inversely with blood flow, and induces significant changes in tissue hemoglobin content and oxygen delivery, is hemodilution.