Markus Cardell

Functional results of angular-stable plate fixation in displaced proximal humeral fractures

INTRODUCTION The availability of angular-stable plate/screw systems led to a euphoric use of these implants for the treatment of displaced proximal humerus fractures. The high implant costs seem to be justified by a potentially improved outcome. PATIENTS AND METHODS Thirty one patients (20 female, 11 male, mean age: 62+/-16 years) with two-, three- and four-part proximal humerus fractures (Neer classification) were operated using the proximal humeral internal locking system (PHILOS). The mean follow-up time was 19+/-3 postoperative months (range: 340-720 days). Functional results (Constant score, UCLA-score) were analysed and compared to an equivalent historic control group of 60 patients operated for the same fracture types using two one-third tubular plates. Additionally, total implant costs for each technique were compared. RESULTS Complications in the PHILOS group included one implant failure with refracture, one secondary dislocation, two cases of subacromial impingement, and two cases of partial avascular necrosis of the humeral head. The mean Constant score (age- and sex-matched) was 80+/-11% for the affected side and 104+/-13% for the healthy side. The UCLA scores were excellent in 10%, good in 67%, and fair in 23% of the patients. Complication rate and functional results did not differ significantly from the control group treated with one-third tubular plates. Implant costs were significantly higher for the PHILOS group (684+/-40 Euro vs. 158+/-20 Euro, p<0.05). CONCLUSION Our study showed similar functional results using either plate. Although the PHILOS plate may provide important advantages in specific situations, such as osteoporotic bone, its use as a standard must be carefully judged under the economic aspect of the significant higher implant costs.

Intra-abdominal pressure development after different temporary abdominal closure techniques in a porcine model

BACKGROUND Decompressive laparotomy followed by temporary abdominal closure (TAC) is an established prophylaxis and treatment for abdominal compartment syndrome. The herein presented study aimed at the comparison of volume reserve capacity and development of intra-abdominal hypertension after forced primary abdominal closure and different TAC techniques in a porcine model. METHODS Eight anesthesized and mechanically ventilated domestic pigs underwent a standardized midline laparotomy. A bag was placed into the abdominal cavity. Before abdominal closure, the bag was prefilled with 3,000 mL water to simulate increased intra-abdominal volume. The intra-abdominal pressure (IAP) was then increased in 2 mm Hg steps up to 30 mm Hg by adding volume (volume reserve capacity) to the intra-abdominal bag. Volume reserve capacity with the corresponding IAP were analyzed and compared for primary abdominal closure, bag silo closure, a zipper system, and vacuum-assisted closure (VAC) with different negative pressures (-50, -100, and -150 mm Hg). Hemodynamic and pulmonary parameters were monitored throughout the experiment. RESULTS Volume reserve capacity was the highest for bag silo closure followed by the zipper system and VAC with primary abdominal closure providing the least volume reserve capacity in the whole IAP range. Of interest, VAC -50 mm Hg resulted in a lower volume reserve capacity when compared with VAC -100 and -150 mm Hg. Pulmonary and hemodynamic parameters demonstrated no significant differences between primary abdominal closure and the evaluated TAC techniques at all IAP levels. CONCLUSIONS The present experimental in vivo study indicates that bag silo closure and zipper systems may be favorable TAC techniques after decompressive laparotomy. In contrast, the VAC techniques resulted in lower volume reserve capacity and therefore may bear an increased risk for recurrent intra-abdominal hypertension in the initial phase after decompressive laparotomy.

Early detection of subclinical organ dysfunction by microdialysis of the rectus abdominis muscle in a porcine model of critical intra-abdominal hypertension.

ABSTRACT The aim of this study was to evaluate microdialysis of the rectus abdominis muscle (RAM) for early detection of subclinical organ dysfunction in a porcine model of critical intra-abdominal hypertension (IAH). Microdialysis catheters for analyses of lactate, pyruvate, and glycerol levels were placed in cervical muscles (control), gastric and jejunal wall, liver, kidney, and RAM of 30 anesthetized mechanically ventilated pigs. Catheters for venous lactate and interleukin 6 samples were placed in the jugular, portal, and femoral vein. Intra-abdominal pressure (IAP) was increased to 20 mmHg (IAH20 group, n = 10) and 30 mmHg (IAH30, n = 10) for 6 h by controlled CO2 insufflation, whereas sham animals (n = 10) exhibited a physiological IAP. In contrast to 20 mmHg, an IAH of 30 mmHg induced pathophysiological alterations consistent with an abdominal compartment syndrome. Microdialysis showed significant increase in the lactate/pyruvate ratio in the RAM of the IAH20 group after 6 h. In the IAH30 group, the strongest increase in lactate/pyruvate ratio was detected in the RAM and less pronounced in the liver and gastric wall. Glycerol increased in the RAM only. After 6 h, there was a significant increase in venous interleukin 6 of the IAH30 group compared with baseline. Venous lactate was increased compared with baseline and shams in the femoral vein of the IAH30 group only. Intra-abdominal pressure–induced ischemic metabolic changes are detected more rapidly and pronounced by microdialysis of the RAM when compared with intra-abdominal organs. Thus, the RAM represents an important and easily accessible site for the early detection of subclinical organ dysfunction during critical IAH.

Acute allograft rejection and immunosuppression: influence on endogenous melatonin secretion.

Abstract:  Melatonin displays a dose‐dependent immunoregulatory effect in vitro and in vivo. Exogenous high‐dose melatonin therapy exerted an immunosuppressive effect, abrogating acute rejection (AR), significantly prolonging transplant survival. Endogenous melatonin secretion, in response to heterotopic rat cardiac allograft transplantation (Tx), was investigated during the AR response and under standardized immunosuppressive maintenance therapy with cyclosporin A (CsA) and rapamycin (RPM). Recipients of syngeneic transplants, and recipients of allogeneic grafts, either untreated or receiving immunosuppressive therapy constituted the experimental groups. Endogenous circadian melatonin levels were measured at 07:00, 19:00, and 24:00 hr, using a novel radioimmunoassay (RIA) procedure, under standardized 12‐hr‐light/dark‐conditions (light off: 19:00 hr; light on: 07:00 hr), before and after Tx. Neither the operative trauma, nor the challenge with a perfused allograft or the AR response influenced endogenous melatonin peak secretion. Immunosuppressive therapy with CsA led to a significant increase in peak secretion, measured for days 7 (212 ± 40.7 pg/mL; P < 0.05), 14 (255 ± 13.9 pg/mL; P < 0.001), and 21 (219 ± 34 pg/mL; P < 0.01) after Tx, as compared with naïve animals (155 ± 25.8 pg/mL). In contrast, treatment with RPM significantly decreased the melatonin peak post‐Tx up to day 7 (87 ± 25.2 pg/mL; P < 0.001), compared with naïve animals (155 ± 25.8 pg/mL). These findings imply a robust nature of the endogenous circadian melatonin secretion kinetics, even against the background of profound allogeneic stimuli. Immunosuppressive maintenance therapy with CsA and RPM modulated early melatonin secretion, indicating a specific secondary action of these drugs. Further studies are necessary to disclose the long‐term effect of immunosuppressive therapy on circadian melatonin secretion in transplant recipients.

Compartment Pressure of the Rectus Sheath Accurately Reflects Intra-Abdominal Pressure in a Porcine Model

BACKGROUND To investigate whether the compartment pressure of the rectus sheath (CPRS) reflects the intra-abdominal pressure (IAP) under various conditions of intra-abdominal hypertension (IAH) in a pig model. METHODS DESIGN Prospective experimental study with in vivo pressure measurements. SETTING Institute for Clinical and Experimental Surgery, University of Saarland. ANIMALS Seven domestic male pigs (body weight 34.8+/-2.5 kg). INTERVENTIONS Stepwise increase and decrease of IAP by means of CO(2) pneumoperitoneum. Continuous direct measurement of the IAP and correspondent indirect IAP measurement techniques including analysis of intravesical pressure (IVP), femoral vein pressure (FVP), and CPRS. RESULTS Bland-Altman analysis comparing direct IAP measurement with correspondent CPRS showed good agreement for IAP between 12 mm Hg and 30 mm Hg (bias -0.5 mm Hg, lower and upper limits of agreement (LLA/ULA) -3.5/2.5 mm Hg). FVP (bias -0.3 mm Hg, LLA/ULA -2.3/1.6 mm Hg) and IVP (bias 0.4 mm Hg, LLA/ULA -2.1/2.9 mm Hg) demonstrated similar results compared with direct IAP measurement. Agreement was worse for all indirect IAP measurement techniques for IAP<12 mm Hg. CONCLUSIONS CPRS accurately reflects IAP for IAP> or =12 mm Hg. Accuracy is similar to established indirect IAP measurement techniques.

The Role of CD26/DPP IV in Preservation of Early Pulmonary Graft Function

CD26 plays a pivotal role in thymic differentation/maturation (Simeoni et al 2002), costimulation (Morimoto 1998), migration (Ikushima et al 2003) and the T cell memory response (De Meester et al 1999). In addition, it possesses enzymatic activity (dipeptidyl peptidase IV, DPP IV), which is linked to its costimulatory efficacy (Tanaka et al 1993, 1994), and has been correlated with immunological competence in vivo (Vanham et al 1993). Circulating DPP IV enzymatic activity is increased in various immune disorders (Fujita et al 1978; Constantinescu et al 1995). We have previously shown that the course of acute cardiac allograft rejection in rats is associated with a significant increase in DPP IV serum activity. Specifically inhibiting DPP IV circulating activity in transplant recipients impaired cellular and humoral immune responses, significantly prolonging graft survival in models of acute cardiac rejection (Korom et al 1997). Following successful kidney transplantation (Tx) in patients on maintenance immunosuppression, systemic DPP IV catalytic activity was markedly reduced for twelve months, and CD26 surface expression on circulating lymphocytes displayed a significant down-regulation for eighteen months post Tx (Korom et al 2002). To further analyze the influence of DPP IV targeted inhibition on the course of early allograft performance, we chose lung Tx in the rat as an alternative model of perfused organ engraftment. In contrast to the heart, the lung constitutes a more challenging immunological set up, due to its vast area of interaction with the milieu exterieur. In this study we demonstrate that specifically targeting circulating DPP IV enzymatic activity in LEW recipients of LBNF1 pulmonary grafts maintains pulmonary macromorphological architecture and preserves ventilatory parameters for up to five days following Tx.