Ian Monk

Effect of hypothermia on lung compliance

The changes in pulmonary compliance have been studied under conditions of total body hypothermia. Five groups of sheep were used; two groups were controls—one for the effects of anaesthesia and the other for normothermic biventricular bypass. The third group was cooled using a femoro-femoral arterio-venous shunt to 20°-23° C. The fourth group was cooled to 15° C. and rewarmed using the Drew technique. The excised lungs of the remaining sheep were studied at 37° and 15° C. (fifth group). The controls showed little change in compliance. The cooled animals showed a decrease in compliance. In the group subjected to hypothermia by the Drew technique, the rewarming phase initially brought a return towards normal compliance. As the temperature rose to 24°-30° C. the improvement in compliance ceased and thereafter compliance decreased for two hours after rewarming. Histologically the lungs were normal. There was no compliance change caused by cooling the excised lungs.

Hemodynamic effects of pulmonary air embolism

Abstract A large bolus of air was injected into the right atrium of sheep. The cardiac output, right ventricular pressure, and arterial PO 2 were studied. It was found that the cardiac output was quickly regained, in less than 10 minutes, despite relatively anoxic levels of arterial oxygen saturation. The cardiac output temporarily exceeded the preinjection level before settling back to this level. The right ventricular pressure rose, corresponding to the regained cardiac output, and then settled to its original levels. The arterial PO 2 fell precipitously and slowly started to rise over the period of study. Bubbles were seen in the coronary arteries during these experiments. A bubble trap was placed across the arch of the aorta which demonstrated that there was no major transpulmonary passage of air.

Aneurysm of the Right Ventricle Caused by Selective Angiocardiography

Two cases are reported of aneurysm formation in the outflow tract and body of the right ventricle following selective angiocardiography. The technic and complications of angiocardiography in our hands have been reviewed, and it is concluded that there is no absolute means of preventing injections of contrast material into the wall of the ventricle, if multiple side hole catheters are used. It seems probably that single end hole catheters are safer than multiple side hole catheters for selective ventriculography.The first patient developed a marked pulsation in the second and third left intercostal spaces together with changes in the plain x-ray that permitted a preoperative diagnosis of aneurysm. The second case was diagnosed at operation. The first patient developed variable cyanosis preoperatively, and during operative correction arterial desaturation together with hypotension. These changes were attributed to outflow tract obstruction by the aneurysm.

Veno-arterial shunting in experimental pulmonary embolism

Abstract Cardiac output and pulmonary arteriovenous shunts were studied in two groups of sheep after pulmonary emboli. Hydrogensaline with a downstream platinum electrode was used as a dilution technique to measure cardiac output and transpulmonary shunting. The first group of sheep were given small clots and the second group one large clot. The recorded shunt was greater in these second group. The cardiac output fell after clot administration and the output/shunt ratio once established remained constant over 1 hour of study. In the animal given the largest clot compatible with survival the majority of the output traversed shunts, suggesting that this mechanism may avert right ventricular failure after massive pulmonary embolus.

A simple instrument to facilitate dissection in the mediastinum from the neck.

The use of a vaginal speculum to gain access to the mediastinum through the neck is described. This enables manipulative procedures to be carried out which include biopsy and also the placement of an electrode in the region of the sino-atrial node where a cardiac pacemaker is being used.

A THREE-BLADED DILATOR FOR TRANS-VENTRICULAR MITRAL VALVOTOMY.

Since Andrew Logan first described the use of an expanding dilator introduced through the left ventricle for the relief of mitral stenosis this method has been widely accepted. The underlying principle is to use a two-bladed dilator, guided into and opened in the stenosed mitral valve, exerting a disruptive force causing separation of the fused commissures of the valve leaflets. This disruptive force must be exerted in two planes only, so that there is at least the theoretical possibility of tearing a valve cusp. In a small personal series of cases, therefore, a three-bladed dilator, together with the index finger used as a fourth dilating agent, has been used since December 1958.

A long-term review of dermal grafts and bronchial reconstruction.

Between 1953 and 1962, 21 patients presented with bronchial strictures. Bronchial reconstruction was carried out on 15 of these while a dermal graft was employed in another six patients. The follow-up period, therefore, is between 10 and 20 years. Bronchial structures lend themselves to satisfactory reconstruction. This review, however, showed that late contraction of a dermal graft may occur even two years after operation.

Mediastinoscopy: A Safe and Useful Procedure in the Investigation of Patients with Intrathoracic Diseases

Mediastinoscopy was performed on 280 patients. The technique is described. A tissue diagnosis was made at mediastinoscopy in 82 cases (29·2%) and, of these, 34 were primary lung carcinomas, one was a secondary deposit from a Grawiiz tumour, 44 were sarcoid tumours and three lymphomas. Of 112 patients with carcinoma for whom the diagnosis was proved at mediastinoscopy, or for whom a negative mediastinoscopy result could be verified at thoracotomy, mediastinoscopy proved to be useful for 94 (83·9%). Of 48 patients with suspected sarcoid, mediastinoscopy gave a positive result for 44 (91·6%). There were only two complications in this series.