Alexander Manche

Expression of soluble endothelial adhesion molecules in clinical cardiopulmonary bypass

Soluble endothelial adhesion molecule expression in clinical cardiopulmonary bypass (CPB) was investigated. Neutrophil-mediated endothelial injury plays an important role in CPB-induced organ dysfunction. The adhesion of neutrophil to the endothelium is central to this process. It has been well documented that CPB induces neutrophil activation and changes in neutrophil adhesion molecule expression, but the effect of CPB on endothelial cell activation is not known. This study was designed to measure soluble endothelial adhesion molecules during CPB. We made serial measurements (by specific enzyme-linked immunoabsorbent assay) of plasma levels of the soluble endothelial adhesion molecules, ICAM-1 and E-selectin in patients undergoing routine CPB (n =7) and in a control group (thoracotomy, n = 3). The results show an initial significant decrease during CPB followed by an increase in plasma E-selectin from 29.3 ± 5.1 ng/ml (mean ± SEM) prebypass to 34.0 ± 5.4 ng/ml at 48 h postbypass. Likewise, plasma ICAM-1 significantly decreased during CPB and then increased from 246.3 ± 38.0 ng/ml before bypass to 324.8 ± 25.0 ng/ml and 355.0 ± 23.0 ng/ml at 24 and 48 h after bypass, respectively. The rise in levels is statistically significant (p < 0.05). This study shows a decrease in circulating ICAM-1 and soluble E-selectin during CPB and an increase in their levels at 48 h after CPB.

Early dialysis in acute kidney injury after cardiac surgery

Acute kidney injury following cardiac surgery (AKICS) remains a frequent cause of major morbidity and mortality. The aim of this study was to examine the influence of timing of dialysis. A retrospective analysis of 3528 patients undergoing cardiac surgery between April 1995 and July 2006 was performed. In group 1 (April 1995-January 2000) intermittent haemodialysis was resorted to when other supportive measures failed. In group 2 (January 2000-July 2006) intermittent haemodialysis was commenced immediately when oliguria did not respond to fluid replacement or single-dose diuretics. In group 1, 49/1511 (3.2%) patients developed AKICS. Thirty-four patients did not receive dialysis and six patients died (18%). Of the remaining 15 patients who underwent dialysis, 13 died (87%). The overall mortality for group 1 AKICS patients was 19/49 (39%). In group 2, 87/2017 (4.3%) patients developed AKICS. Thirty-one patients did not require dialysis and none died. Of the 56 patients who were dialysed, 14 died (25%). During January 2005-July 2006, mortality following dialysis fell further to 17% (4/24). The overall mortality for group 2 patients developing AKICS was 14/87 (16%). Although the incidence of AKICS increased from 3.2% to 4.2%, earlier dialysis resulted in significantly improved survival (P=0.00001).

Is there a biomechanical cause for spontaneous pneumothorax

OBJECTIVES Primary spontaneous pneumothorax has long been explained as being without apparent cause. This paper deals with the effect of chest wall shape and explains how this may lead to the pathogenesis of primary spontaneous pneumothorax. METHODS Rib cage measurements were taken from chest radiographs in 12 male pneumothorax patients and 12 age-matched controls. Another group of 15 consecutive male thoracic computerised tomography (CT) were investigated using paramedian coronal and sagittal CT reconstructions to assess apical lung shape. A finite element analysis (FEA) model of a lung apex was constructed, including indentations for the first rib guided by CT scan data, to assess pleural stress. This model was tested using different anteroposterior diameter ratios, producing a range of thoracic indexes. RESULTS The pneumothorax patients had a taller chest (P = 0.03), wider transversely (P = 0.009) and flatter (P = 0.03) when compared with controls, resulting in a low thoracic index. Prominent rib indentations were found anteriorly and posteriorly on the lung surface, especially on the first rib on CT. FEA of the lung revealed significantly higher stress (×5-×10) in the apex than in the rest of the lung. This was accentuated (×4) in low thoracic index chests, resulting in 20-fold higher stress levels in their apex. CONCLUSIONS The FEA model demonstrates a 20-fold increase in pleural stress in the apex of chests with low thoracic index typical of spontaneous pneumothorax patients. Mild changes in thoracic index, as occurring in females or with aging, reduce pleural stress. Spontaneous pneumothorax occurring in young male adults may have a biomechanical cause.

Mechanism of sternotomy dehiscence

OBJECTIVES Biomechanical modelling of the forces acting on a median sternotomy can explain the mechanism of sternotomy dehiscence, leading to improved closure techniques. METHODS Chest wall forces on 40 kPa coughing were measured using a novel finite element analysis (FEA) ellipsoid chest model, based on average measurements of eight adult male thoracic computerized tomography (CT) scans, with Pearsons correlation coefficient used to assess the anatomical accuracy. Another FEA model was constructed representing the barrel chest of chronic obstructive pulmonary disease (COPD) patients. Six, seven and eight trans-sternal and figure-of-eight closures were tested against both FEA models. RESULTS Comparison between chest wall measurements from CT data and the normal ellipsoid FEA model showed an accurate fit (P < 0.001, correlation coefficients: coronal r = 0.998, sagittal r = 0.991). Coughing caused rotational moments of 92 Nm, pivoting at the suprasternal notch for the normal FEA model, rising to 118 Nm in the COPD model (t-test, P < 0.001). The threshold for dehiscence was 84 Nm with a six-sternal-wire closure, 107 Nm with seven wires, 127 Nm with eight wires and 71 Nm for three figure-of-eights. CONCLUSIONS The normal rib cage closely fits the ellipsoid FEA model. Lateral chest wall forces were significantly higher in the barrel-shaped chest. Rotational moments generated by forces acting on a six-sternal-wire closure at the suprasternal notch were sufficient to cause lateral distraction pivoting at the top of the manubrium. The six-sternal-wire closure may be successfully enhanced by the addition of one or two extra wires at the lower end of the sternotomy, depending on chest wall shape.

Cardiopulmonary bypass line sternal wrapping for protection and haemostasis

Sternal marrow haemostasis is often obtained with the application of bone wax, with potential side effects pertaining to sternal wound healing. We illustrate an alternative technique which also offers some protection to sternal edges. Two lengths of tubing from the discarded cardiopulmonary bypass (CPB) circuit are cut longitudinally on one side. After sternotomy they are placed across each sternal edge and kept in position by two stitches and the spreader blades. They are removed just before sternal closure.

External rib structure can be predicted using mathematical models: An anatomical study with application to understanding fractures and intercostal muscle function.

As ribs adapt to stress like all bones, and the chest behaves as a pressure vessel, the effect of stress on the ribs can be determined by measuring rib height and thickness. Rib height and thickness (depth) were measured using CT scans of seven rib cages from anonymized cadavers. A Finite Element Analysis (FEA) model of a rib cage was constructed using a validated approach and used to calculate intramuscular forces as the vectors of both circumferential and axial chest wall forces at right angles to the ribs. Nonlinear quadratic models were used to relate rib height and rib thickness to rib level, and intercostal muscle force to vector stress. Intercostal muscle force was also related to vector stress using Pearson correlation. For comparison, rib height and thickness were measured on CT scans of children. Rib height increased with rib level, increasing by 13% between the 3rd and 7th rib levels, where the 7th/8th rib was the widest part or “equator” of the rib cage, P < 0.001 (t‐test). Rib thickness showed a statistically significant 23% increase between the 3rd and 7th ribs, P = 0.004 (t‐test). Intercostal muscle force was significantly related to vector stress, Pearson correlation r = 0.944, P = 0.005. The three nonlinear quadratic models developed all had statistically significant parameter estimates with P < 0.03. External rib morphology, in particular rib height and thickness, can be predicted using statistical mathematical models. Rib height is significantly related to the calculated intercostal muscle force, showing that environmental factors affect external rib morphology. Clin. Anat. 28:512–519, 2015.

A hypothesis for reactivation of pulmonary tuberculosis: How thoracic wall shape affects the epidemiology of tuberculosis.

This study was aimed at determining the cause for the high incidence of tuberculosis (TB) reactivation occurring in males with a low body mass index (BMI). Current thinking about pulmonary TB describes infection in the lung apex resulting in cavitation after reactivation. A different hypothesis is put forward for TB infection, suggesting that this occurs in subclinical apical cavities caused by increased pleural stress due to a low BMI body habitus. A finite element analysis (FEA) model of a lung was constructed including indentations for the first rib guided by paramedian sagittal CT reconstructions, and simulations were conducted with varying antero‐posterior (AP) diameters to mimic chests with a different thoracic index (ratio of AP to the transverse chest diameters). A Pubmed search was conducted about gender and thoracic index, and the effects of BMI on TB. FEA modeling revealed a tenfold increase in stress levels at the lung apex in low BMI chests, and a four‐fold increase with a low thoracic index, r2 = 0.9748 P < 0.001. Low thoracic index was related to BMI, P = 0.001. The mean thoracic index was statistically significantly lower in males, P = 0.001, and increased with age in both genders. This article is the first to suggest a possible mechanism linking pulmonary TB reactivation to low BMI due to the flattened thoracic wall shape of young male adults. The low thoracic index in young males may promote TB reactivation due to tissue destruction in the lung apex from high pleural stress levels. Clin. Anat. 28:614–620, 2015.

Cardiopulmonary bypass line sternal wrapping: technical tips

Cardiopulmonary bypass line sternal wrapping (SW) is a new approach to sternal care which avoids bone wax and offers mechanical protection and a shield from bacterial contamination, with beneficial effects on sternal healing. Since its introduction in February 2008, the technique has undergone some developments: it is possible to harvest internal thoracic arteries with SW in place and its haemostatic properties have improved.

Internal rib structure can be predicted using mathematical models: An anatomic study comparing the chest to a shell dome with application to understanding fractures

The human rib cage resembles a masonry dome in shape. Masonry domes have a particular construction that mimics stress distribution. Rib cortical thickness and bone density were analyzed to determine whether the morphology of the rib cage is sufficiently similar to a shell dome for internal rib structure to be predicted mathematically. A finite element analysis (FEA) simulation was used to measure stresses on the internal and external surfaces of a chest‐shaped dome. Inner and outer rib cortical thickness and bone density were measured in the mid‐axillary lines of seven cadaveric rib cages using computerized tomography scanning. Paired t tests and Pearson correlation were used to relate cortical thickness and bone density to stress. FEA modeling showed that the stress was 82% higher on the internal than the external surface, with a gradual decrease in internal and external wall stresses from the base to the apex. The inner cortex was more radio‐dense, P < 0.001, and thicker, P < 0.001, than the outer cortex. Inner cortical thickness was related to internal stress, r = 0.94, P < 0.001, inner cortical bone density to internal stress, r = 0.87, P = 0.003, and outer cortical thickness to external stress, r = 0.65, P = 0.035. Mathematical models were developed relating internal and external cortical thicknesses and bone densities to rib level. The internal anatomical features of ribs, including the inner and outer cortical thicknesses and bone densities, are similar to the stress distribution in dome‐shaped structures modeled using FEA computer simulations of a thick‐walled dome pressure vessel. Fixation of rib fractures should include the stronger internal cortex. Clin. Anat. 28:1008–1016, 2015.

Intrathoracic schwannoma with Horner syndrome

Horner syndrome (HS) results from the interruption of the sympathetic pathway to the eye and face, and describes a collection of signs consisting of ipsilateral miosis, partial ptosis, anhidrosis and apparent enophthalmos. It is a clinical observation, and has a plethora of possible causes, ranging from the benign to the malignant. Involvement of the stellate ganglion on the sympathetic chain by malignant tumours of the lung is a well-recognised cause of HS. On the other hand, HS secondary to the excessive growth of a benign intrathoracic neoplasm is a very rare finding, with only a few cases described in the literature. Our patient was found to have such a diagnosis when he presented to medical attention with a 1-month history of cough that was associated with features of HS that he had ignored for the preceding 9 years.