An assessment of the potential use of transthoracic impedance measurement for the non-invasive monitoring of lung injury following cardiac surgery.

AIM: Lung injury commonly occurs following cardiac surgery. More severe forms are associated with a high mortality. In order to diagnose it and monitor its progress with treatment, measurement of extravascular lung water is necessary. This is usually measured using either a double-indicator dilution or single-indicator technique. Both require intravascular lines and expensive consumables which make them unsuitable for the routine monitoring of cardiac surgical patients. It has been suggested that the measurement of bioelectrical impedance could provide a non-invasive alternative which would allow routine measurement in these patients. METHODS: Extravascular lung water (EVLW) and index (EVLWI) were measured in 23 patients undergoing elective coronary artery bypass graft surgery at 3 time points before and after surgery using the PiCCO system. At the same times the Transthoracic Impedance ratio (TTIr) was also measured using the Bodystat Dual Scan 2005. RESULTS: The corresponding measurements of TTIr were compared statistically with both EVLW and EVLWI. The resulting correlation coefficients were very low (<0.1). CONCLUSION: Transthoracic Impedance does not appear to reflect extravascular lung water and is therefore unlikely to be useful in the routine monitoring of cardiac surgical patients.

Reference values of pulmonary function tests for Canadian Caucasians.

A multicentre, cross-sectional study was carried out in six centres across Canada to establish a national standard for pulmonary function tests using healthy, lifetime nonsmokers, with each centre aiming to test 10 men and 10 women from each decade from 20 to 80 years of age. Data from each centre were used to derive prediction equations for each centre, and pooled data from all centres (total: 327 women and 300 men) were used to derive Canadian predicted equations. The predictive models were compared with three widely used published models for selected tests. It was found that, in general, the equations modelled for each centre could be replaced by the models obtained when pooling all data (Canadian model). Comparisons with the published references showed good agreement and similar slopes for most tests. The results suggest that pulmonary function test results obtained from different centres in Canada were comparable and that standards currently used remain valid for Canadian Caucasians.

Childhood asthma predisposes to spontaneous pneumomediastinum.

Spontaneous pneumomediastinum is a rare condition for which potentially life threatening differential diagnoses must be excluded. A case is presented of a young man with a history of severe childhood asthma, who was successfully treated conservatively.

Tamponade as a rare complication of CPAP use following cardiac surgery.

A 64-year-old woman developed tamponade more than 48 hours following cardiac surgery. The cause for this was haemorrhage from the site of multiple attempted cannulations of the right internal jugular vein. However this was a secondary haemorrhage and appeared to be precipitated by the use of CPAP on the second postoperative day. CPAP should be used with caution following difficult neckline insertions.

Intraluminal rotatory device: a hypothesized new approach for the treatment of type B aortic dissections.

Acute dissection is the most common and frequently fatal catastrophic event to effect the aorta. Current treatments are unsatisfactory, particularly for Type B dissections where the mortality is excessive (approaching 33%) yet the late complication rate is high. It is hypothesized that an alternative approach would be to introduce an intraluminal freely rotating device via the femoral artery to lie adjacent to the site of the initial intimal tear. As a result it is predicted that the local shear stress would become zero, effectively arresting the dissection process. At the same time, the centrifugal force developed by the device would oppose the layers of the dissection, increasing the likelihood of false lumen obliteration. Such an approach may result in less short-term mortality and a lower long-term complication rate than current treatments.

The effect of subcutaneous tumour implantation in a murine lung tumour model.

OBJECTIVES: It was hypothesized that if tumour were implanted subcutaneously within a Millipore Chamber (MPC), then this would result in an 'anti-tumour' immune response. Such an approach could have potential as an adjuvant tumour therapy when combined with surgical resection. A murine lung tumour model was used to test this hypothesis. METHODS: Lung tumours were induced in 245 syngeneic mice by intraperitoneal 4-[methylnitrosamino]-1-[3 pyridyl]-1-butanone. In addition, MPCs were implanted containing either normal lung (Group A) or lung tumour (Group B). Group C had no implanted MPCs. These animals were sacrificed between 1 and 8 weeks following implantation and the stage of lung tumour development as assessed by the surface tumour count (STC) of their left lungs was compared between the different groups. The presence of CD4(+) and CD8(+) T cells in the local reactions surrounding the implanted chambers was also compared between Groups A and B at 1 week post-implantation. RESULTS: At 1 week, the STC was significantly lower in Group B (2.4+/-0.6) than in both Groups A (4.7+/-0.6) and C (4.9+/-0.9; P=0.02). In addition, at 1 week, there was a significantly greater proportion (%) of CD4(+) cells in the local reactions of Group B (52+/-3) than in Group A (35+/-3; P=0.001). Between 2 and 8 weeks post-implantation, there were no further significant differences in tumour development between the groups. CONCLUSIONS: Although the findings of an 'early' response were consistent with the hypothesized benefit of tumour implantation within MPCs, the later results have not confirmed its potential as an adjuvant therapy.

Assessment of murine lung tumour development: a comparison of two techniques.

Two techniques (surface photographic analysis [SPA] and microscopic tumour analysis [MTA]) are described for assessing the stage of tumour development induced by intraperitoneal 4-(methyl nitrosamino)- 1-(3 pyridyl)-1-butanone in syngeneic A/J mice. Parameters used to assess the number and size of tumours were surface tumour count (STC), surface tumour area (STA). and relative tumour surface area (RTSA)--all using SPA; and mean tumour count (MTC), mean tumour area, and relative tumour area (RTA)--all using MTA. In a study examining the possible effects of Millipore chamber implantation on lung tumours, the stage of tumour development was assessed in 239 mice using both SPA and MTA. Statistically significant correlations (Spearman-Rank) were apparent between the derived parameters: STC vs. MTC (r = 0.6, P <0.0001); STA vs. mean tumour area (r = 0.5, P <0.0001); RTSA vs. RTA (r = 0.4, P <0.0001). Therefore, it is concluded that SPA--the simpler technique--is an appropriate method for assessing the stage of tumour development in this model.

An unusual cause of unilateral facial pain.

Cardiac pain that is referred to the face is a common symptom in patients with angina pectoris, but unilateral facial pain referred from a non-ischaemic cardiac source is rare. We report a case of unilateral facial pain that occurred in relation to a large pericardial effusion and which resolved on drainage of the effusion.

Subcutaneously implanted tumour: an hypothesized novel approach to individualized immunotherapy for lung carcinoma.

A novel approach to immunotherapy for the treatment of lung carcinoma is hypothesized. If a lung tumour removed at operation is implanted subcutaneously within a Millipore chamber in that patient, then a local immune response may be induced. It is suggested that this subcutaneously induced immune response could improve the prognosis of the underlying tumour either of its own accord or by its use as an adoptive immunotherapy. Spread of the tumour locally would be prevented by containment within the Millipore chamber. The hypothesis has been supported by experimental observations from a pilot study.

Mismatch of aortotomy and saphenous vein graft size: a simple solution.

Bleeding may occur at the proximal anastomosis of an aortocoronary bypass graft due to the aortotomy being larger than the vein graft diameter. This results in the wall of the vein being under tension, so that the anastomotic suture or further stitches may cut through. A partial thickness suture placed as a pursestring around the aortotomy may alleviate this situation, resulting in a smaller aortotomy with reduced vein wall tension, improved hemostasis, and a more satisfactory anastomotic vein contour.

Current methods to reduce the adverse haematological consequences of cardiopulmonary bypass.

Bleeding remains a significant cause of morbidity after cardiac surgery and results in a major demand on blood transfusion capacity. The aetiology is multifactorial, but platelet dysfunction is the most important cause. Because of the potential risks of heterologous blood transfusion, a number of techniques have been developed to reduce its need. These can broadly be divided into three categories. First, modification of bypass methods and the use of agents such as aprotinin can reduce blood loss. Second, more use can be made of the patient's own blood through predonation of autologous blood or blood conservation techniques. Finally, transfusion policy can be modified so that a lower postoperative haemoglobin level is accepted. However, a method with which to preoperatively predict those patients who will bleed significantly remains elusive.

Peri-infarct pursestring for repair of subacute cardiac rupture.

A 55-year-old woman presented with cardiac tamponade after an inferior myocardial infarction. At surgical exploration there was an extensive area of hematoma associated with cardiac rupture. Rather than infarctectomy and ventricular repair an alternative approach was taken. The patient was successfully managed by the placement of a peri-infarct pursestring together with a superficial stitch closing the exit point of the cardiac rupture.

Retrograde pulmonary embolectomy by flushing of the pulmonary veins.

A glue embolization of a cerebral arteriovenous malformation in a 3-year-old boy was complicated by a massive pulmonary embolus due to glue entering the venous circulation. Attempted pulmonary embolectomy via pulmonary arteriotomy after emergency cardiopulmonary bypass was unsuccessful. However, retrograde flushing of the pulmonary veins with cold saline solution produced large quantities of embolus through the pulmonary arteriotomy. Bypass was discontinued uneventfully with no residual cardiopulmonary problems.

Potential use of the intercostal artery as an in situ graft: a cadaveric study.

The third to eighth intercostal arteries (ICAs) were bilaterally dissected in 10 cadavers to assess their length and possible routes to coronary arteries if used as in situ grafts. The mean lengths for the intercostal arteries harvested were 27.0 +/- 2.9 cm on the left and 27.4 +/- 3.2 cm on the right. The shortest anatomic route to the coronary arteries of the in situ ICAs harvested was medial to the lung and either superior to or inferior to the hilum. By using either the superior or inferior routes in situ ICAs were long enough to reach the major coronary artery territories in all cadavers. The most suitable ICAs for grafting the coronary arteries and the shortest routes were as follows: left anterior descending--left fifth ICA by inferior route; circumflex coronary artery-left fifth ICA by inferior route; and right coronary artery-right seventh ICA by inferior route. We conclude that it is anatomically feasible to use the intercostal artery as an in situ graft in coronary artery operation.