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R Lobato

Publications and source records attributed to R Lobato.

At least 19 recordsLinked to original sources
PubMed2005

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance.

A liquid isooctane (C(8)H(18)) filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min(-1), and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm(3) air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio.

Dose-Response Relationship, Radiation↗
PubMed2004

Commissioning of a medical accelerator photon beam Monte Carlo simulation using wide-field profiles.

A method for commissioning an EGSnrc Monte Carlo simulation of medical linac photon beams through wide-field lateral profiles at moderate depth in a water phantom is presented. Although depth-dose profiles are commonly used for nominal energy determination, our study shows that they are quite insensitive to energy changes below 0.3 MeV (0.6 MeV) for a 6 MV (15 MV) photon beam. Also, the depth-dose profile dependence on beam radius adds an additional uncertainty in their use for tuning nominal energy. Simulated 40 cm x 40 cm lateral profiles at 5 cm depth in a water phantom show greater sensitivity to both nominal energy and radius. Beam parameters could be determined by comparing only these curves with measured data.

Algorithms↗
PubMed2004

Free ion yield observed in liquid isooctane irradiated by gamma rays. Comparison with the Onsager theory.

We have analysed data on the free ion yield observed in liquid isooctane irradiated by 60Co gamma rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian-type function and an exponential function. A linear dependence between the free ion yield and the external electric field has been found at low-electric-field values (E < or = 1.2 x 10(3) V mm(-1)) in excellent agreement with the Onsager theory. At higher electric field values, we obtain a solution in power series of the external field using the Onsager theory.

Cobalt Radioisotopes↗
PubMed2004

[Contrast-enhanced sonourethrography versus conventional miction cystourethrography in the assessment of the urethra: preliminary study].

BACKGROUND AND AIMS: Voiding cystourethrography (VCUG) is the first choice imaging modality for assessing the urethra, but this technique exposes patients to ionizing radiation. Cystosonography with echocontrast (CS) has proved to be a reliable technique to detect and grade vesicoureteral reflux (VUR) without exposing patients to ionizing radiation, but its capacity to adequately study the urethra has yet to be demonstrate in large series of patients. The aim of this study is to demonstrate the reliability of contrast-enhanced CS for assessing the urethra by comparing the results with those of the VCUG. MATERIAL AND METHODS: 108 patients were studied with ultrasound (US) using a galactose-based contrast agent. This exam was always followed by VCUG. Basal and voiding urethral US studies were performed with. Patients were studied in supine decubitus position. Girls were examined by longitudinal translabial approach, with the probe (a 7.5 MHz liner array transducer) positioned longitudinally at the introitus, to evaluate the bladder neck and urethra. In boys the transducer was initially placed longitudinally in the escrotum at ventral root of the penis to assess the bladder neck and proximal bulbar urethra, and then displaced distally toward the penile urethra. On basal study the echogenic urethral mucosa and the collapsed sonolucent urethral lumen were indentified and measured when distended. The patients were asked to void with the probe in place. During voiding attention was focused on elasticity and distention of urethral walls, as well as in the caliber of the entire urethra. Patients unable to void during either CS or VCUG were excluded. RESULTS: The bladder neck and the entire urethra were well demonstrate with CS. All females and 43 males showed a normal urethra both in CS and VCUG. Four patients were dignoses of posterior urethral valves (PUV) with CS and confirmed at VCUG, one patient had anterior urethral valves and 5 showed urethral stenosis at both techniques. Three patients with a vesicosphincteric dysinergia, 14 with resected PUV and one with a resected syringocele were adequately evaluated. Twelve girls showed vaginal reflux. The information provided by CS was equivalent to the VCUG in all patients but two with a syringocele (only seen on VCUG). CONCLUSIONS: CS is a reliable imaging modality sufficiently sensitive and specific to study the urethra, adding dynamic information to VCUG and can be used as a complement to VCUG.

Child↗
PubMed2004

[Pyeloplasty follow-up. How and how long?].

INTRODUCTION: Some controversies still persist about the pueloplasty follow-up and this study aims to determine which test should be done in these patients during the follow-up and for how long these patients should be under control. PATIENTS AND METHODS: Forty six children who underwent to pueloplasty were retrospectively reviewed and those with contralateral renal abnormalities were excluded from study. Six children were lost to follow-up and were excluded. Of 40 p (25 M, 14 F) who fulfilled the requirements of this study, 28 were diagnosed prenatally and 28 had a left UPJ obstruction. All children were diagnosed by renal ultrasound, diuretic renography and excretory urogram (except 2). Mean age at Anderson Hynes pyeloplasty was 5.1 months and mean follow-up was 6.1 years. Renal ultrasound at 3 months and every year, and a diuretic renography at 1 year were performed in all children during follow-up. In some of them diuretic renography was repeated. RESULTS: At 3 months renal ultrasound demonstrated a significant hydronephrosis decrease in all children (p < 0.0001) but not in further controls. Differential renal function remained unchanged after pyeloplasty and during follow-up. However, there was a significant UPJ drainage improvement after pyeloplasty and during follow-up (p < 0.0001, p < 0.005). Any child needed a second pyeloplasty procedure and all of them showed a normal UPJ drainage in the antegrade ureterogram performed on the 5th postoperative day, except one. CONCLUSIONS: Differential renal function did not improve after pyeloplasty in our children. If renal ultrasound 3 months after pyeloplasty demonstrated a significant hydronephrosis decrease and at 1 year diuretic renography reveals a normal UPJ drainage any change should be expected in the long-term follow-up.

Analysis of Variance↗
PubMed2003

Posterior urethral valves: prognostic factors.

OBJECTIVE: To determine which variables besides bladder dysfunction can help to predict the outcome of renal function in boys with posterior urethral valves (PUV). PATIENTS AND METHODS: All 40 patients with PUV in this retrospective study were diagnosed and began treatment in our hospital within the first 3 months of life, and have had >or= 5 years of follow-up. At the time of diagnosis, 33 were in renal insufficiency (RI) and seven had normal renal function (RF). At the time of the study 16 were in chronic renal failure (CRF) and 24 had normal RF. We compared their RF (initial and during follow-up), vesico-ureteric reflux (VUR), urinary tract infection (UTI), proteinuria, hypertension, renal echogenicity, final patient age and initial management. RESULTS: The mean serum creatinine values before and after initial treatment were worse in boys who developed CRF than in those who did not (P = 0.08); the mean glomerular filtrate rate (GFR) at 1 year old was 52 mL/min/1.73 m2 in the former and 102 in the latter (P < 0.001). Proteinuria was present during the follow-up in 79% of patients in CRF and in only 17% of those with normal RF. All patients who developed CRF had echogenic renal changes while only 53% of the others had (P < 0.01). Other variables showed no statistically significant differences (VUR, UTI, hypertension and final patient age). Of 33 patients in RI at diagnosis, nine were treated by valve ablation and 24 by temporary pyelo-ureterostomy. The initial mean serum creatinine value was worse in the latter than in the former (20.8 vs 13.0 mg/L). However, at 1 year old the mean GFR was better in the latter than in the former (P < 0.05). These GFR differences persisted during the first years of life but had disappeared by the fifth. CONCLUSIONS: The most significant prognostic factor for the future development of CRF is the GFR at 1 year old. The onset of proteinuria during the follow-up is associated with a worse prognosis. Echogenic renal changes may help to identify those dysplastic kidneys that will develop RI. Neonatal boys in RI who underwent pyelo-ureterostomy had better RF during the first years of life than those who underwent valve ablation.

Adolescent↗
PubMed2002

Bladder dysfunction as a prognostic factor in patients with posterior urethral valves.

OBJECTIVE: To investigate the extent to which different types of bladder dysfunction can affect long-term renal function in boys with posterior urethral valves (PUV). PATIENTS AND METHODS: Renal and bladder function were retrospectively assessed in 59 boys with PUV (mean age 10 years, range 5-17). All patients included in the study had at least 4 years of follow-up and their bladder behaviour had been evaluated in at least two urodynamic studies. At the time of the study, of the 59 PUV boys, 37 had normal renal function and 22 had end-stage renal disease (ESRD). RESULTS: Of the 59 boys with PUV evaluated by urodynamic studies, 25 had normally behaving bladders (42%) and 34 had some type of bladder dysfunction (58%). Of the 22 in ESRD, 15 had abnormally behaving bladders (68%) and only seven had bladders with normal behaviour (32%). Of the 37 boys with normal renal function, 19 had dysfunctional bladders (51%) and 18 had normal bladders (49%). Instability was found in 17 of 19 boys with bladder dysfunction and normal renal function. On the contrary among 22 boys with ESRD, poor compliance was the most frequent urodynamic pattern (eight, 53%) while instability was only found in five. Overall, eight of nine boys with poorly compliant bladders, two of three with myogenic failure and a five of 22 with instability were in ESRD, and this situation occurred at an earlier age in patients with poorly compliant bladders. CONCLUSION: Bladder dysfunction should be considered as a prognostic factor in renal failure. Those with poor bladder compliance and myogenic failure have the worst outcome, while bladder instability was associated with the lowest incidence of renal failure.

Adolescent↗
PubMed2001

Influence of the interval between the administration of doxorubicin and paclitaxel on the pharmacokinetics of these drugs in patients with locally advanced breast cancer.

PURPOSE: The combination of bolus doxorubicin followed by a 3-h infusion of paclitaxel has high antitumor activity in patients with metastatic breast cancer, but is limited by unexpected cardiac toxicity. In contrast, the administration of the two drugs 16 h apart has similar antitumor activity but less cardiac toxicity. The purpose of this study was to compare the pharmacokinetics of these drugs when doxorubicin administration preceded paclitaxel by 30 min or by 24 h. PATIENTS AND METHODS: Women with locally advanced breast cancer were treated with doxorubicin (60 mg/m2 i.v. bolus) followed 24 h later by paclitaxel (200 mg/m2 i.v. over 3 h) for six cycles (four before and two after surgery). In one of the first two cycles doxorubicin preceded paclitaxel by 30 min instead of 24 h, with plasma sampling for pharmacokinetic analysis up to 48 h. Determination of drug levels in plasma was done by HPLC. RESULTS: A total of 28 patients were included. No clinical cardiac toxicity was observed but five patients discontinued doxorubicin-paclitaxel treatment after four cycles because of a decrease in LVEF of at least 15% from baseline or to less than 50%. While paclitaxel pharmacokinetics were not changed, there was a 30% and an 80% increase in the AUC0, 24h for doxorubicin and doxorubicinol, respectively, when the drugs were administered 30 min instead of 24 h apart. Even when paclitaxel was given 24 h after doxorubicin, there was a rebound 240% increase in the plasma concentration of doxorubicinol. CONCLUSIONS: Paclitaxel interferes with the pharmacokinetics of doxorubicin leading to higher systemic exposure to both doxorubicin and doxorubicinol, which is more evident when the plasma concentration of the anthracyclines is higher. This interference may explain the higher incidence of cardiac toxicity observed when the two drugs are administered within a short interval.

Adult↗
PubMed2000

Does neonatal pyeloureterostomy worsen bladder function in children with posterior urethral valves?

PURPOSE: We determine whether long-term bladder dysfunction is more frequent in children with posterior urethral valves who undergo early supravesical urinary diversion (pyeloureterostomy) than in those who undergo valve ablation. MATERIALS AND METHODS: Urodynamic studies were performed in 59 boys with severe posterior urethral valves who were divided into 2 groups based on initial treatment of valve ablation (30) and bilateral pyeloureterostomy (29). RESULTS: Of the 59 boys 25 (42%) had a normal bladder, including 11 with an over distended bladder and 34 (58%) had bladder dysfunction, including instability in 22, poor compliance in 9 and myogenic failure in 3. Of the 30 boys initially treated with valve ablation 14 (46.6%) had a normal bladder, including 7 with an over distended bladder and 16 (53.4%) had bladder dysfunction, including instability in 10, poor compliance in 4 and myogenic failure in 2. Of the 29 boys initially treated with temporary bilateral pyeloureterostomy 11 (38%) had normal bladders, 4 with an over distended bladder and 18 (62%) had bladder dysfunction, including instability in 12, poor compliance in 5 and myogenic failure in 1. There were no statistically significant differences in the number or type of bladder dysfunction between the diversion and valve ablation groups. CONCLUSIONS: Therefore, temporary pyeloureterostomy did not affect bladder function adversely in the long term.

Humans↗
PubMed2000

[Complex and complicated syndactylia. Review and treatment progress].

Complex syndactyly is generally defined as abnormal digital interconnection by bone, but sometimes simple syndactyly with complicated cutaneous, musculotendinous or neurovascular interconnections should be considered complex as well. Additionally, complex syndactyly involving anomalous bones (delta phalanx, brachiphalangism...) falls in different category called "complicated". 35 patients with complex or complicated congenital syndactyly are studied and 58 children with cutaneous syndactyly due to burns and epidermolysis bullosa are analyzed as well.

Child↗
PubMed2000

[Impact of complete resection on survival of patients with large neuroblastoma].

UNLABELLED: The aim of our study is to assess the role of complete resection after chemotherapy in stage 3 and 4 (INSS) neuroblastoma. MATERIAL AND METHODS: We treated in the period 1990-1997 a group of 71 infants and children with neural tumors. There were 63 neuroblastomas (median age: 24.8 +/- 25 months, median 18). 47 were abdominal, 13 thoracic, 2 pelvic and 1 cervical. Survival rate (Kaplan-Meier) in patients with or without complete resection of the tumor were assessed (Mantel Cox). RESULTS: 14 of 17 patients with stage 3 tumors and only 8 of 23 with stage 4 survive. All patients with stage 3 undergoing complete resection are alive, whereas only 4 of 7 with incomplete resection survive (p < 0.01). In contrast, the effort and risk of resection do not appear to be worth in stage 4. Two kidneys, one spleen and a portion of the pancreas were removed to perform complete tumor removal. CONCLUSIONS: Complete resection in stage 3 neuroblastoma after chemotherapy improves survival, and radical surgery seems justified even if neighboring structures have to be removed. Radical surgery does not seem to be useful in stage 4 neuroblastoma.

Child, Preschool↗
PubMed1999

Supraceliac aortic clamping during the anhepatic phase of experimental orthotopic liver transplantation.

BACKGROUND: The pig tolerates simultaneous clamping of the liver pedicle and inferior vena cava poorly, so venovenous bypass has to be used during the anhepatic phase of experimental orthotopic liver transplantation (OLT). The aim of this work is to assess whether clamping of the supracoeliac aorta during the anhepatic phase (AP) of experimental OLT in pigs allows transplantation in stable hemodynamic conditions. METHODS: Fourteen pigs (weight, 16 to 18 kg) received whole liver grafts from 14 age-matched donors and were subsequently divided into two groups: group I, OLT without venovenous bypass during the AP, group II, OLT with supracoeliac aortic clamping during the AP. Variables analyzed were cardiac output (CO) and related variables, mean systemic arterial pressure (MAP), mixed venous oxygen saturation (SvO2), hepatic artery and portal vein blood flow, systemic and hepatic O2 supply and uptake (SDO2, SVO2, HDO2, HVO2, respectively), liver enzymes, glucose, creatinine, and electrolytes. RESULTS: In group I, CO, MAP, and SvO2, decreased during the AP (anhepatic) in comparison with baseline (preanhepatic) values (CO, 3.60+/-0.74, preanhepatic, v. 1.21+/-0.25 L x min(-1), anhepatic; P<.05. MAP, 97+/-12, preanhepatic, v. 43+/-17 mm Hg, anhepatic; P<.05. SvO2, 91.6+/-5.6, preanhepatic v. 70.0+/-12.5%, anhepatic; P<.05), and SDO2/SVO2 increased by 16% (preanhepatic) to 33% (anhepatic; P<.05). In group II, CO decreased during the anhepatic phase by only 21% (3.82+/-0.81, preanhepatic, v. 3.07+/-0.99 L x min(-1), anhepatic; not significant), the MAP increased significantly (100+/-8, preanhepatic, v. 135+/-4 mm Hg, anhepatic; P<.05), and SVO2, SDO2, SVO2, and SDO2/SVO2 remained unchanged. After revascularization, none of these variables differed significantly between groups, and levels of liver enzymes, glucose, creatinine, urea, and electrolytes were similar in both groups, both before and aftertransplantation. CONCLUSIONS: Experimental OLT can be carried out in pigs without venovenous bypass, but it leads to severe hemodynamic disturbances. Clamping of the supraceliac artery during the AP is well tolerated and results in excellent hemodynamic stability, so it may prove to be a useful technique in liver transplantation in animals, such as dogs or pigs, that do not tolerate simultaneous clamping of the liver pedicle and inferior vena cava as well as human beings.

Animals↗
PubMed1999

Penetration of cefuroxime into chronically inflamed sinus mucosa.

OBJECTIVES: Despite its seeming relevance, limited information exists about antibiotic sinus tissue penetration and how it is affected by inflammation. Thus the reason for the present investigation. STUDY DESIGN: A randomized, open, multiple-dose, pharmacological study, employing cefuroxime axetil, an approved oral antimicrobial for the treatment of acute bacterial rhinosinusitis, was developed. METHODS: Twenty subjects, selected for surgery because of chronic rhinosinusitis, were randomly allocated to receive either a short (3-8 d) or a long (9-14 d) preoperative treatment regime with 500 mg cefuroxime axetil BID, the last dosage being taken 3 to 4 hours before surgery. At the operation, tissue samples were collected at specific sinonasal sites for both pharmacological determination of antibiotic levels and histopathological assessment of the degree of inflammation. The blood levels of the drug were simultaneously assayed. RESULTS: Cefuroxime kinetic behavior on chronically inflamed mucosa was shown to be, for the most part, dependent on the blood levels, regardless of the inflammatory state. Distribution was even throughout the different sinus cavities, and the tissue levels were still, 3 to 4 hours after dosing, above the reported minimum inhibitory concentration (MIC) values for some of the most prevalent sinus pathogens. The extended treatment course did not seem to add any extra histopathological or pharmacological benefit. CONCLUSIONS: Cefuroxime penetrates adequately and uniformly into chronically inflamed sinus mucosa, apparently unaffected by the degree of inflammation, in a way not dissimilar to its pharmacokinetic behavior in the normal state. Persistent MIC levels for common pathogens still warrant antimicrobial efficacy for a significant period of time after dosing.

Adult↗
PubMed1999

[The long-term behavior of the valve bladder as a function of the initial treatment and its effect on early kidney failure].

In approximately 25-40% of infants presenting with posterior urethral valves (PUV) renal insufficiency will develop before adolescence. In some these patients, renal dysplasia, bladder dysfunction and mismanagement may precipitate renal failure at even earlier age. The goals of this study were to determine whether long-term bladder dysfunction was more frequent in children who underwent early temporary pyelostomy than in those who underwent valve ablation, and to know if bladder dysfunction and mismanagement, in some patients, could be responsible of early renal failure. Urodynamic studies were performed in 59 boys with severe PUV divided into two groups based on initial treatment. A) Valve ablation (30 p.); B) Cutaneous pyeloureterostomy (29 p.). At the end of the study 22 boys had chronic renal failure. Of the 59 boys, 42% (25 p.) had bladders with overdistended or normal behaviour, 58% (34 p.) had bladder dysfunction (instability 37%, low compliance 15%, myogenic failure 5%). The 89% of low compliance bladders, 66% of myogenic failure and 23% of those with instability were in CRF. No difference at all was found in bladder function between boys treated as neonates by high diversion or valve ablation. Of the group in chronic renal failure (22 p.), only 7 patients (32%) had bladders with normal behaviour and in five of these patients a mismanagement was directly related with a quicker renal deterioration. The 58% of our boys with severe PUV have some type of bladder dysfunction. Neonatal pyelo-ureterostomy does not increase long-term bladder dysfunction. Surgical mismanagement should be added to bladder dysfunction as contributors to earlier renal failure.

Child, Preschool↗
PubMed1998

Long-term follow-up of patients with biliary atresia successfully treated with hepatic portoenterostomy. The importance of sequential treatment.

The outcome of 18 biliary atresia (BA) patients (5 male, 13 female; age range 10.7-22.5 years; mean 15.4+/-0.7 years) treated with hepatic portoenterostomy (HPE) and jaundice-free for more than 10 years without liver transplantation (LT) is analyzed retrospectively. Eight of these patients subsequently required LT (age at LT 12. 8+/-0.5 years, range 10.5-15.2 years); 3 children (aged 11.6, 13.2 and 14.1 years, respectively) had episodes of gastrointestinal variceal bleeding associated with other signs of severe disease and are now candidates for LT; and among the 7 asymptomatic patients (age range 11.2-22.5 years; mean 15.9+/-2.1 years), 5 had sonographic and biochemical signs of moderate portal hypertension (PH). In order to analyze whether the age at transplantation influences the survival of children transplanted for BA, we also reviewed the outcome of 71 BA patients transplanted at our hospital between 1986 and 1996. All the children older than 10 years at the time of LT were alive; only patients younger than 10 years died following LT (n = 15). We conclude that the natural outcome of extrahepatic BA is toward PH, fibrosis, and cirrhosis, even in those cases successfully treated with HPE. In our experience, the results of sequential treatment with HPE and LT were excellent.

Adolescent↗
PubMed1998

A multicenter trial on the efficacy of using tirilazad mesylate in cases of head injury.

OBJECT: The authors prospectively studied the efficacy of tirilazad mesylate, a novel aminosteroid, in humans with head injuries. METHODS: A cohort of 1120 head-injured patients received at least one dose of study medication (tirilazad or placebo). Eighty-five percent (957) of the patients had suffered a severe head injury (Glasgow Coma Scale [GCS] score 4-8) and 15% (163) had sustained a moderate head injury (GCS score 9-12). Six-month outcomes for the tirilazad- and placebo-treated groups for the Glasgow Outcome Scale categories of both good recovery and death showed no significant difference (good recovery in the tirilazad-treated group was 39% compared with the placebo group in which it was 42% [p=0.461]; death in the tirilazad-treated group occurred in 26% of patients compared with the placebo group, in which it occurred in 25% [p=0.750]). Subgroup analysis suggested that tirilazad mesylate may be effective in reducing mortality rates in males suffering from severe head injury with accompanying traumatic subarachnoid hemorrhage (death in the tirilazad-treated group occurred in 34% of patients; in the placebo group it occurred in 43% [p=0.026]). No significant differences in frequency or types of serious adverse events were shown between the treatment and placebo groups. CONCLUSIONS: Striking problems with imbalance concerning basic prognostic variables were observed in spite of the large population studied. These imbalances concerned pretreatment hypotension, pretreatment hypoxia, and the incidence of epidural hematomas. In future trials of pharmacological therapy for severe head injury, serious consideration must be given to alternative randomization strategies. Given the heterogeneous nature of head injury and the identification of populations that do relatively well with standard therapy, target populations with a higher risk for mortality and morbidity may be more suitable for clinical trials of such agents.

Adult↗
PubMed1997

The effect of hepatic vascular exclusion on hepatic blood flow and oxygen supply--uptake ratio in the pig.

The hemodynamic disturbances produced by total hepatic vascular exclusion (THVE) for 40 minutes were studied in 7 pigs (19-22 kg). THVE was produced by clamping the hepatic pedicle and inferior vena cava, above and below the liver, for a 40-minutes period, followed by unclamping. Compared to baseline values, 30 minutes after onset of THVE, there was a decrease in cardiac output (3.86 +/- 0.55 vs 1.23 +/- 0.23 L x min-1), systemic arterial pressure (97.54 +/- 13.58 vs 43.43 +/- 11.38 mm Hg), and pulmonary artery pressure (16.57 +/- 6.38 vs 12.57 +/- 3.58) and an increase in systemic and pulmonary vascular resistance (1772 +/- 198 vs 2351 +/- 462, and 182 +/- 66 vs 361 +/- 124 dyn x s x cm-5 respectively). As a result of diminished cardiac output, the systemic oxygen supply decreased (461 +/- 131 vs 101 +/- 46 ml x min-1), but the systemic oxygen extraction rate rose from 17.3% t0 31.2%. Thirty minutes after unclamping, the changes had reversed and all the parameters tended to normalize. Total hepatic blood flow 30 minutes after unclamping was higher than at baseline (5.08 +/- 1.2 vs 6.66 +/- 0.67 ml x min-1 x 100 g-1), because of the increase in portal blood flow (4.52 +/- 1.21 vs 6.07 +/- 0.70 ml x min-1 x 100 g-1). There were no significant differences in hepatic oxygen supply and uptake at baseline and after unclamping (152.6 +/- 23.0 vs 187.0 +/- 34.7 and 22.7 +/- 4.9 vs 28.7 +/- 8.4 ml O2 respectively). AST rose (29 +/- 7 vs 136 +/- 91 U/l), but there was no change in the remaining liver enzymes, glucose, creatinine and serum electrolytes, so we conclude that the hemodynamic disturbances produced by 40 minutes of THVE are manageable and spontaneously reversible. Liver metabolism was not greatly disturbed, so THVE was judged to be a viable technique to be added to the surgeon's range of options.

Analysis of Variance↗