Evaluation of bosentan, pinacidil and nitroprusside on human pulmonary arteries: comparison with rat pulmonary arteries.

Bosentan (endothelin ETA/ETB antagonist), pinacidil (potassium channel opener) and nitroprusside (nitric oxide donor) were examined on isolated ring preparations of human intralobar pulmonary artery (3rd-5th generation, internal radius > or = 1 mm), rat main pulmonary artery (1st generation; internal radius > or = 1 mm) and rat intralobar pulmonary artery (3rd generation; internal radius 0.1-0.3 mm). The potency of endothelin-1 was the same in all three artery types. In human intralobar artery and rat main pulmonary artery, bosentan (3 and 10 microM) shifted the endothelin-1 concentration response curve to a higher concentration range (endothelin-1 concentration ratios, in human intralobar and rat main pulmonary artery, respectively: 3 microM bosentan, 4.5 and 8.1; 10 microM bosentan, 13.5 and 19.5), but caused no significant block of endothelin-1 in rat intralobar artery. The latter finding may be due to the reported presence of ETB receptors in rat intralobar arteries and the higher potency of bosentan on ETA than on ETB receptors. In contrast, the potencies of nitroprusside and pinacidil (relaxation of submaximal contractions to the thromboxane-mimetic, U46619) agreed on human and rat intralobar arteries but were 6 to 16-fold lower than on rat main pulmonary artery. We conclude that data obtained on pulmonary arteries from rats can be useful in predicting the effects of vasoactive drugs in human pulmonary arteries but selection of the most appropriate rat artery for study will depend on the drug group under investigation. For potassium channel openers and nitric oxide donors, good agreement between human and rat data will be found when using pulmonary arteries from the same anatomical location even though they differ markedly in size. In contrast, for endothelin antagonists, agreement is more likely to be found in arteries of comparable size, despite their different anatomical locations.

Carcinoma of the lung: a two-year experience at the Austin Hospital, Victoria.

All patients attending the Austin Hospital, Melbourne, with the diagnosis of carcinoma of the lung in the two year period 1974 to 1975 were reviewed. There 211 patients in the series, comprising 1.2% of all patients admitted to hospital, and the methods of diagnosis and management were reviewed. Squamous and anaplastic carcinomata were equally frequent, comprising 75% of all cases, and there was a significantly lower incidence of squamous cell carcinoma in females (6.3%) compared with other cell types (20% to 30%). Sputum cytology was the most rewarding single source of tissue diagnosis, and bronchoscopy and mediastinoscopy next most helpful. Only 25% of the patients were fit for surgical treatment, and only 20% of the carcinomata were able to be resected.

Mechanisms of healing in the injured lung treated with the Nd-YAG laser.

An experimental study was done to evaluate the pattern of healing after sealing an incision in the pulmonary parenchyma with the Nd-YAG laser. Gross and histologic examinations of healing were compared with those of lung cauterized or sutured with chronic catgut. The results indicate that the use of the Nd-YAG laser to seal small vessels and air leaks has distinct advantages over cautery or suture closure of incisions in pulmonary tissue.

Chronic intrapulmonary foreign bodies.

Two cases of chronically retained foreign bodies are presented, demonstrating that a long delay may exist between a penetrating injury and the manifestation of a severe symptom, such as haemoptysis or recurrent infection, referable to a retained foreign body. In only one of these cases was the diagnosis of retained foreign body considered the most likely pre-operatively. Some diagnostic and management problems arising in such situations are discussed.

Experimental and clinical use of the YAG laser in the management of pulmonary neoplasms.

Animal experiments were performed with evaluation of the use of the neodymium-YAG (yttrium-aluminum-garnet) laser in the trachea, bronchi, and pulmonary parenchyma. Histologic evaluation of incisions into the lung was assessed by multiple sections over a 5-week period and comparisons were made of incisions closed with chronic catgut or coagulated with electric cautery or by the laser. These studies indicated that the laser is more effective in controlling parenchymal bleeding and air leaks than either the cautery or chromic catgut and produces less local tissue reaction. The Nd-YAG laser has been used clinically to treat patients with inoperable obstructing and bleeding carcinomas of the trachea and main bronchi to open the involved airway and to restore pulmonary function. Fifteen patients have had 26 treatments using the Nd-YAG laser. Total laser time was limited to 15 minutes with 0.5-second pulses of 50 to 80 watts being delivered via the fiberoptic and straight bronchoscope as indicated. It is extremely effective in controlling hemoptysis from recurrent endobronchial lesions, and obstructing lesions in the trachea and main stem bronchus can be treated quite successfully with excellent palliation. It is apparent that continued clinical use of the Nd-YAG laser as palliative therapy for bleeding and obstructing tumors of the tracheobronchial tree is indicated and expanded use at the time of thoracotomy to control lung parenchymal bleeding and air leaks should be considered in the future.

Computerised tomography does not predict N2 disease in patients with lung cancer.

BACKGROUND: Mediastinal node involvement in primary lung cancer determines the staging and prognosis of the patient, and as these nodes can be seen on the computerised tomography (CT) scan of the chest it is a temptation to diagnose malignant involvement if the nodes appear enlarged. However, initial experience with mediastinal node mapping at lung resection demonstrated this extrapolation to be unreliable and misinterpretation of enlarged nodes on CT may lead to misdiagnosis and prejudice the patient's management. AIM: To demonstrate that the sensitivity, specificity, and accuracy of the CT to detect malignant mediastinal nodes is too low to use size of node on CT as representative of malignant involvement. METHODS: One hundred and fifty-three sequential patients with resectable lung cancer were studied with preoperative CT. Two radiologists determined the preoperative T and N status from these studies with nodes of 1.5 cm or larger diagnosed abnormal. These results were compared to the results of subsequent node mapping performed after lung resection. RESULTS: Sensitivity was found to be 26%, specificity to be 81% and overall accuracy 69%--too low to justify the diagnosis of N2 disease on size of 1.5 cm or larger. CT is not a valid means of diagnosing malignant involvement of mediastinal nodes.

Asphyxia while swallowing solid food caused by bronchial compression: a variant of the pneumonectomy syndrome.

A 40 year old man presented with recurrent episodes of dyspnoea whilst swallowing solid food. He had undergone right pneumonectomy and thoracoplasty for recurrent pneumonias and empyema 23 years previously. Solid food boluses appeared to cause bronchial obstruction by compressing the surgically distorted left main bronchus. This is a new variant of the post pneumonectomy syndrome.

Intramural haematoma of the oesophagus complicated by perforation.

A case is presented where spontaneous bleeding into the wall of the oesophagus was exacerbated by anticoagulant therapy. Subsequently, iatrogenic, full-thickness perforation of the oesophagus occurred during endoscopy and, ultimately, oesophagectomy was required. If this condition is suspected on clinical grounds, the most appropriate sequence of investigations would appear to be contrast radiography in the first instance with cautious use of oesophagoscopy.