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A Nahum

Publications and source records attributed to A Nahum.

At least 37 records · Page 2Linked to original sources
PubMed1999

Comparison of radiation side-effects of conformal and conventional radiotherapy in prostate cancer: a randomised trial.

BACKGROUND: Radical radiotherapy is commonly used to treat localised prostate cancer. Late chronic side-effects limit the dose that can be given, and may be linked to the volume of normal tissues irradiated. Conformal radiotherapy allows a smaller amount of rectum and bladder to be treated, by shaping the high-dose volume to the prostate. We assessed the ability of this new technology to lessen the risk of radiation-related effects in a randomised controlled trial of conformal versus conventional radiotherapy. METHODS: We recruited men with prostate cancer for treatment with a standard dose of 64 Gy in daily 2 Gy fractions. The men were randomly assigned conformal or conventional radiotherapy treatment. The primary endpoint was the development of late radiation complications (> 3 months after treatment) measured with the Radiation Therapy and Oncology Group (RTOG) score. Indicators of disease (cancer) control were also recorded. FINDINGS: In the 225 men treated, significantly fewer men developed radiation-induced proctitis and bleeding in the conformal group than in the conventional group (37 vs 56% > or = RTOG grade 1, p=0.004; 5 vs 15% > or = RTOG grade 2, p=0.01). There were no differences between groups in bladder function after treatment (53 vs 59% > or = grade 1, p=0.34; 20 vs 23% > or = grade 2, p=0.61). After median follow-up of 3.6 years there was no significant difference between groups in local tumour control (conformal 78% [95% CI 66-86], conventional 83% [69-90]). INTERPRETATION: Conformal techniques significantly lowered the risk of late radiation-induced proctitis after radiotherapy for prostate cancer. Widespread introduction of these radiotherapy treatment methods is appropriate. Our results are the basis for dose-escalation studies to improve local tumour control.

Follow-Up Studies↗
PubMed1998

Sperm parameters after early left varicocele treatment.

OBJECTIVE: We evaluated whether early treatment for left varicocele can improve sperm parameters. DESIGN: Patient follow-up and comparison with control groups. SETTING: Surgical department of a Children's Hospital and a university infertility-care center. PATIENT(S): Nineteen patients who underwent surgery for left varicocele as adolescents (mean +/- SD, 14.11 +/- 1.59 years) were followed up as adults (mean +/- SD, 19.37 +/- 1.16 years). MAIN OUTCOME MEASURE(S): A testicular examination was performed and varicocele staging was done at the time of surgery. Andrologic examination and semen analysis were done 2-8 years later. Semen results were compared with those of two age-matched control groups of 19 healthy, randomly selected subjects and 19 unoperated patients suffering from left varicocele of the same degree. RESULT(S): The mean values of sperm parameters in the patient study group were similar to those of the healthy controls except that the sperm concentration was significantly lower. However, sperm motility and morphology mean values in the patient study group were significantly higher than those of the unoperated patients. CONCLUSION(S): This study indicates that surgery in adolescence can be useful, possibly because the testis is developing at that age. Large-scale, double-blind controlled trials on early treatment of left varicocele are needed to identify possible markers of disease severity.

Adolescent↗
PubMed1998

Volume recruitment and oxygenation in pulmonary edema: a comparison between HFOV and CMV.

PURPOSE: In acute lung injury, edema floods alveoli decreasing mean lung volume (MLV) and increasing pulmonary venous admixture (Ova/Qt). We reasoned that a ventilatory strategy that uses large tidal volumes (VT) might recruit volume differently than a strategy that uses very small VT (high-frequency oscillatory ventilation, HFOV) which may require an inflation maneuver to total lung capacity (TLC) for full recruitment. MATERIALS AND METHODS: We studied six dogs with pulmonary edema induced by oleic acid injury and compared HFOV with conventional mechanical ventilation (CMV). Increasing mean airway opening pressure (Pao) from 6 to 14 cm H2O raised MLV from 932+/-162 to 1,550+/-210 mL and from 872+/-145 to 1,242+/-192 mL during CMV and HFOV, respectively, whereas Qva/Qt decreased from 24.1+/-8.5 to 9.3+/-4.3% and from 42.2+/-6.8 to 30.4+/-9.3%. We repeated our measurements at a Pao of 14 cm H2O after an inflation maneuver to TLC. RESULTS: Intlation to TLC recruited additional lung volume and decreased Qva/Qt further only during HFOV. After an inflation to TLC, we observed a rapid isobaric volume loss from the deflation limb of the pressure-volume curve during both CMV and HFOV. CONCLUSIONS: We conclude that after oleic acid injury in dogs pressure-volume hysteresis has two components: a recruitable portion associated with gas exchange improvement and a nonrecruitable portion. At the level of PEEP used in this study (8.5 cm H2O), full lung recruitment during HFOV required inflation to TLC, whereas during CMV it was accomplished by the relatively large VT.

Animals↗
PubMed1997

Effect of mechanical ventilation strategy on dissemination of intratracheally instilled Escherichia coli in dogs.

OBJECTIVE: To test the effect of different mechanical ventilation strategies on dissemination of intratracheally instilled Escherichia coli in dogs and to determine the extent and distribution of lung damage. DESIGN: Prospective, randomized study. SETTING: Experimental animal laboratory. SUBJECTS: Eighteen anesthetized and paralyzed dogs. INTERVENTIONS: We studied the effect of three ventilatory strategies based on two variables: transpulmonary pressure and positive end-expiratory pressure (PEEP). Group 1 animals (n = 6) were ventilated with a PEEP of 3 cm H2O and a tidal volume of 15 mL/kg, which generated an end-inspiratory transpulmonary pressure of < or = 15 cm H2O. In group 2(n = 6), tidal volume was adjusted to generate a transpulmonary pressure of 35 cm H2O and PEEP was set to 3 cm H2O. In group 3(n = 6), tidal volume was also adjusted to yield a transpulmonary pressure of 35 cm H2O but PEEP was set to 10 cm H2O. In each group, we instilled approximately 10(8) colony-forming units of E. coli into the trachea of the dogs and ventilated them with the chosen tidal volume and PEEP for 6 hrs afterward. MEASUREMENTS AND MAIN RESULTS: We measured the pressure-volume relationship (pressure-volume curve) of the respiratory system before and 6 hrs after bacterial instillation. We obtained blood cultures before and 0.5, 1,2,3,4,5, and 6 hrs after bacterial instillation. After 6 hrs, the lungs were removed for histologic (histologic score) and gravimetric (wet-to-dry weight ratio, WW/DW) analysis. During the experiment 0, 5, and 1 dogs developed positive blood cultures in groups 1, 2, and 3, respectively. The number of dogs that developed bacteremia in group 2 was significantly greater than in the other two groups (p < .05). In group 1, pressure-volume curves demonstrated a lower inflection point which was greater than the end-inspiratory transpulmonary pressure suggesting that low transpulmonary pressure/low PEEP strategy ventilated aerated regions without expanding atelectatic areas. In group 2, pressure-volume curves demonstrated both a lower inflection point and an upper deflection point which were spanned by the tidal volume, suggesting that high transpulmonary pressure/low PEEP strategy might have caused both overdistention and cyclic closure and reopening. In group 3, pressure-volume curves demonstrated only a upper deflection point which was less than the maximal alveolar tidal pressure. At the end of the experimental protocol, group 2 manifested the most lung injury as assessed by gravimetric and histologic indices of lung injury. WW/DW of group 2(13.1 +/- 1.0 (SD); p < .05) was greater than groups 1 and 3(7.5 +/- 1.2 and 8.6 +/- 1.0, respectively). Similarly, the overall weighted histologic injury score for group 2 (1.19 +/- 0.26; p < .02) was greater than for groups 1 and 3 (0.82 +/- 0.20 and 0.88 +/- 0.22, respectively). For groups 2 and 3, the overall weighted histologic injury scores of the dependent regions were greater than the nondependent regions (p < .004). CONCLUSIONS: We conclude that the ventilatory strategy most likely to overdistend the lungs while allowing repetitive opening and closure of alveoli (group 2) facilitated bacterial translocation from the alveoli to the bloodstream and increased lung injury, as determined by histologic and gravimetric analysis. PEEP ameliorated these effects, despite lung overdistention, but increased histologic and gravimetric indices of lung injury in dependent as compared with the nondependent regions.

Animals↗
PubMed1996

Accuracy of pelvic radiotherapy: prospective analysis of 90 patients in a randomised trial of blocked versus standard radiotherapy.

The aim of this study was to assess the accuracy of pelvic radiotherapy during a trial of blocked radiotherapy at the Royal Marsden Hospital, UK. Prospective evaluation was performed on 90 patients receiving CT planned pelvic radiotherapy using weekly anterior-posterior and lateral portal films. Field placement errors (FPEs) were calculated by comparing field centres of each film with a designated point of interest. Data was evaluated to calculate the overall treatment simulator differences, the number of error free treatments, and mean treatment-simulator position and to evaluate the role of systematic versus random errors. Age, weight, disease site, position of treatment, fractionation, blocked versus conventional techniques were assessed for their effect on treatment accuracy. The mean absolute error between treatment and simulator films was anterior right-left (ARL) 0.25 cm, anterior superior-inferior (ASI) 0.32 cm, lateral anterior-posterior (LAP) 0.42 cm, and lateral superior-inferior (LSI) 0.28 cm. On average the field centre was displaced by 0.66 cm (standard deviation, S.D. = 0.34) from that intended. On each treatment day 29% of anterior films and 45% of lateral films had at least one 0.5 cm error. Overall 59% of treatments had at least one 0.5 cm error and 9% a 1.0 cm error. The field centre was more than 0.5 cm from the position intended in 66% of treatments and over 1 cm for 14% of treatments. Analysis of variance showed that both random and systematic errors occurred in all directions. Though random errors were of similar magnitude in all direction (variance sigma 2 = 0.06-0.09 cm2); systematic errors showed a 4-fold variation being greatest in the LAP direction (sigma 2 = 0.19 cm2) and least the ARL direction (sigma 2 = 0.048 cm2). No factor consistently predicted for worse outcome in all directions. Hypofractionated treatments were less accurate in the LSI direction (P > 0.05). Systematic errors were associated in the ARL direction with hypofractionation (P < 0.01) and, in the LSI direction with weight (P < 0.03) and age (P < 0.05). We conclude that significant random and systematic errors can occur during pelvic radiotherapy especially in the LAP direction. These results suggest that in the absence of a customised immobilisation device, to cover 95% of errors, margins of 0.6 cm for RL and SI directions and 0.9 cm for AP direction should be allowed between the planning and clinical target volumes. However, ideally, each centre should determine their own margin requirements according to local clinical practice.

Age Factors↗
PubMed1996

Adjuncts to mechanical ventilation.

Adjunctive ventilatory strategies have been developed to improve oxygenation and carbon dioxide (CO2) removal during mechanical ventilation of critically ill patients. These techniques allow clinicians to attain their clinical goals at lower levels of ventilatory support. In this article, the authors discuss extracorporeal CO2 removal, venovenous intravena caval oxygenator, and tracheal gas insufflation as adjuncts to CO2 removal and nitric oxide, surfactant replacement therapy, perfluorocarbon-associated gas exchange, and prone positioning as adjuncts to oxygenation.

Animals↗
PubMed1996

Distal effects of tracheal gas insufflation: changes with catheter position and oleic acid lung injury.

We separated distal (turbulence-related) and proximal (dead space washout-related) effects of tracheal gas insufflation (TGI) by comparing the effects of straight and inverted catheters. We reasoned that the inverted catheter was unlikely to remove CO2 from conducting airways distal to its orifice. In six normal dogs during TGI at 10 l/min, advancing the catheters from 10 to 1 cm above the main carina decreased dead space volume by 29 +/- 12 and 12 +/- 6 ml (P < 0.04) with the straight and inverted catheters, respectively. By comparison, the tracheal volume between 10 and 1 cm above the carina was 15 +/- 2 ml. In another set of dogs (n = 5), we examined the distal effects of TGI before and after oleic acid-induced lung injury. During TGI at 10 l/min before and after oleic acid injury, the differences in arterial PCO2 between the straight and inverted catheters were 5 +/- and 9 +/- 6 Torr (P < 0.18), respectively. Our data suggest that distal effects of TGI become more pronounced as the catheter tip is positioned closer to the main carina. The distal effects of TGI were not diminished after oleic acid injury when minute ventilation was maintained constant.

Animals↗
PubMed1996

Tracheal gas insufflation: catheter effectiveness determined by expiratory flush volume.

Used adjunctively during mechanical ventilation, tracheal gas insufflation (TGI) improves CO2 elimination, principally by decreasing effective anatomic dead space. Continuing lung deflation at end- expiration raises the end-expiratory C02 concentration within the proximal airway, and could theoretically reduce the efficiency of a given catheter flow. To test this possibility, we designed a series of experiments that examined the influence of TGI delivery patterns on the efficiency of CO2 elimination. Using a gating device, catheter flow was delivered selectively during desired portions of expiration. Paralyzed, ventilated dogs were studied at short and extended inspiratory time fractions (TI/TT) with inspiratory tidal volume and ventilator frequency held constant. The expiratory flush volume, not the pattern of gas delivery, determined the observed decline in PaCO2, provided that the end-expiratory period was included in the catheter flush period. Despite continuing end-expiratory lung deflation (extended TI/TT), catheter effectiveness remained the same at matched expiratory flush volumes. To determine if enhanced distal mixing at the higher catheter flows required during the extended TI/TT (to match expiratory flush volume) masked a decrease in efficiency, we repeated the experiment with a tip-inverted catheter. We again found that matched catheter delivered expiratory volumes were similarly effective. With or without ongoing lung deflation, the volume of gas flushed during the expiratory period determined the effectiveness of TGI, provided that inspired minute ventilation remains unchanged and end-expiration is included in the catheter flush period.

Analysis of Variance↗
PubMed1996

Effect of tracheal gas insufflation on demand valve triggering and total work during continuous positive airway pressure ventilation.

Tracheal gas insufflation (TGI) improves CO2 clearance and may reduce work of breathing by lowering the required minute ventilation (VE). However, TGI might also impair the ability to trigger the ventilator, because to lower external circuit pressures, inspiratory effort must outstrip catheter flow rate (Vc) and overcome the dynamic hyperinflation caused by TGI. We studied these effects using a two-chamber lung model of the respiratory muscles (RM) and lungs (L). The RM-chamber was ventilated using a sinusoidal flow pattern with a tidal volume (VT) of 0.5 L at various peak inspiratory flow rates (Vpk) to simulate differences in effort intensity. The L-chamber was connected to a 60-L/min continuous flow circuit with a 10 cm H2O positive end-expiratory pressure valve and to 3 different ventilatory demand valve circuits, each set at continuous positive airway pressure (CPAP) of 10 cm H2O. We used continuous TGI at 0, 2.5, 5, 10, and 15 L/min. The work of triggering (W-trig) increased with increasing Vc and decreased with increasing Vpk. The L-ventilator failed to trigger when Vc was 15 L/min and Vpk was 20 L/min. At a fixed VE, the effect of TGI on total mechanical inspiratory work (W-tot) was relatively small and varied among the different CPAP systems used. We conclude that weak patients may fail to open the demand valve of the CPAP system during TGI at high catheter flow rates. The net effect of TGI on the effort made by ventilated patients would depend not only on the interactions between TGI and the ventilator, but also on the efficiency of TGI in decreasing dead-space and lowering the VE requirement.

Humans↗
PubMed1996

[Impact of deltamethrin impregnated mosquito nets on the transmission of malaria in the coastal lagoon area, Benin].

We have measured the entomological impact of insecticide treated nets on malaria transmission at Ganvie, a village in the coastal and lagoon area of Benin. The nets we have impregnated belong to the population of this village. Men and women of Ganvie used the nets everyday against nuisance biting. Then, the nets we have impregnated are not experimental nets introduced in the village. We have treated 3,230 nets, that means 79% of the nets of this village which counts 20,000 inhabitants. After treating the nets, the inoculation rate due to Anopheles gambiae s.s. and A. melas has decreased from 11 to 4.6 infected bites per man/year, that represents 58.5% of reduction of malaria transmission. We have also observed that the parturity rate of anopheles has decreased from 45.3 to 38.8%. We are sure that the entomological performances due to the impregnation will increase more if the inhabitants of Ganvie change their behaviours. They must reduce the frequency of impregnated net wash and repair the teared nets.

Animals↗
PubMed1995

Inspiratory tidal volume sparing effects of tracheal gas insufflation in dogs with oleic acid-induced lung injury.

PURPOSE: Tracheal gas insufflation (TGI) improves the efficiency of conventional mechanical ventilation (CMV) by reducing the series dead space of the airways. Consequently, application of TGI as an adjunct to CMV may permit reducing tidal volume (VT) while limiting CO2 retention. We tested the extent to which panexpiratory TGI allows reduction of VT while maintaining PaCO2 constant in an oleic acid-induced lung injury model. METHODS: We studied six anesthetized, paralyzed, and mechanically ventilated dogs. Oleic acid injury was induced by injecting 0.09 mL/kg of oleic acid into the right atrium. After stabilization of lung injury the VT-sparing effect of TGI was tested by progressively increasing catheter flow rate (Vc) from 2 to 5, 10, and 15 L/min while decreasing VT by an amount that maintained PaCO2 constant (approximately 47 mm Hg) with respect to baseline (Vc = 0 L/min). RESULTS: Tidal volume was decreased from a baseline value of 0.360 +/- 0.030 L to 0.238 +/- 0.054 L at Vc of 15 L/min. The reduction in VT was associated with a decrement in peak and end-inspiratory plateau airway opening pressure from 32 +/- 3 to 28 +/- 6 cm H2O and from 25 +/- 2 to 21 +/- 3 cm H2O, respectively. Total physiological dead space fraction decreased from a baseline value of 0.60 +/- 0.08 to 0.31 +/- 0.20 during TGI at 15 L/min. TGI did not affect cardiac output, PaO2, or pulmonary venous admixture. CONCLUSION: We conclude that TGI can be a useful adjunct to CMV during acute lung injury to limit VT while avoiding CO2 retention.

Analysis of Variance↗
PubMed1995

Effect of tracheal gas insufflation on gas exchange in canine oleic acid-induced lung injury.

OBJECTIVE: To determine the effect of tracheal gas insufflation on gas exchange in oleic acid-induced lung injury in dogs. DESIGN: Prospective, longitudinal study. SETTING: University research laboratory. SUBJECTS: Five mongrel dogs. INTERVENTIONS: The dogs were anesthetized, paralyzed, and mechanically ventilated. Lung injury was induced by infusing 0.09 mL/kg of oleic acid and pulmonary artery occlusion (wedge) pressure (PAOP) was increased to 15 mm Hg by infusing fluids to enhance pulmonary edema formation. After 60 mins, PAOP was allowed to decrease to 5 mm Hg and was maintained at 5 mm Hg for 60 mins to stabilize the pulmonary edema. We studied the effect of tracheal gas insufflation on gas exchange at low and high end-expiratory lung volumes achieved by a positive end-expiratory pressure of 5 and 12 cm H2O, respectively. The FIO2 values of the ventilator and catheter were equivalent (0.6). Each tracheal gas insufflation stage at low and high end-expiratory lung volume was preceded and followed by conventional mechanical ventilation stages without tracheal gas insufflation. During transitions between conventional mechanical ventilation and tracheal gas insufflation, end-expiratory lung volume was maintained constant by adjusting positive end-expiratory pressure while monitoring esophageal pressure and inductive plethysmography. Tidal volume was maintained constant throughout the protocol (0.40 L). MEASUREMENTS AND MAIN RESULTS. At end stage, we measured PaCO2, PaO2, total physiologic deadspace fraction, and venous admixture, which were 43 +/- 4 torr (5.7 +/- 0.5 kPa), 325 +/- 6 torr (43.3 +/- 0.8 kPa), 53 +/- 3%, and 4.0 +/- 0.3% before oleic acid lung injury, respectively. After oleic acid injury at low end-expiratory lung volume, these variables were 55 +/- 4 torr (7.3 +/- 0.5 kPa), 73 +/- 13 torr (9.7 +/- 1.7 kPa), 61 +/- 4%, and 50 +/- 7%, respectively. During tracheal gas insufflation at low end-expiratory lung volume conditions, PaCO2 and the total physiologic deadspace fraction decreased significantly (p < .05) to 45 +/- 4 torr (6.0 +/- 0.5 kPa) and 50 +/- 5%, respectively. Under high end-expiratory lung volume conditions, PaCO2 and the total physiologic deadspace fraction were 55 +/- 7 torr (7.3 +/- 0.9 kPa) and 61 +/- 6%, respectively; during tracheal gas insufflation, these variables decreased to 43 +/- 4 torr (5.7 +/- 0.5 kPa) and 52 +/- 5%, respectively (p < .05). Increasing end-expiratory lung volume improved both PaO2 and venous admixture (p < .05) but tracheal gas insufflation had no significant effect on oxygenation efficiency when end-expiratory lung volume was held constant. CONCLUSIONS: Tracheal gas insufflation augmented alveolar ventilation effectively in the setting of oleic acid-induced lung injury in dogs. When end-expiratory lung volume and tidal volume were kept constant, tracheal gas insufflation did not affect oxygenation.

Animals↗
PubMed1995

Efficacy of expiratory tracheal gas insufflation in a canine model of lung injury.

Tracheal gas insufflation (TGI) improves the efficiency of CO2 elimination by reducing the CO2-laden dead space of the airways. The effect of TGI on PaCO2 diminishes in the setting of acute lung injury (ALI) because an increased alveolar component dominates the total physiologic dead space. Nevertheless, adopting a strategy of permissive hypercapnia should partially offset the decreased efficacy of TGI by increasing CO2 concentration in the proximal airways. To examine these issues we studied the CO2 removal efficacy of expiratory TGI as an adjunct to conventional mechanical ventilation (CMV) before and after oleic acid-induced lung injury (OAI). We first examined the effect of TGI before and after OAI, keeping tidal volume (VT) and frequency constant, and allowing PaCO2 to increase after OAI. We then tested TGI efficiency after matching PaCO2 after OAI to its pre-OAI level by increasing VT (post-OA/VT stage). PaCO2 was 53 +/- 3, 79 +/- 21, and 52 +/- 4 mm Hg in the pre-OAI, post-OAI, and post-OA/VT stages of CMV, respectively. The corresponding decrements in PaCO2 produced by TGI at a flow rate of 10 L/min were 16 +/- 3, 24 +/- 10, and 10 +/- 2 mm Hg, respectively. TGI decreased total physiologic dead space per breath (VD) by 56, 31, and 28 ml during the pre-OAI, post-OAI, and post-OA/VT stages, respectively. Despite a smaller reduction in VD during the post-OAI stage, the effect of TGI on PaCO2 was preserved because of the relatively high PaCO2 prior to its initiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗