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The human intercostal space has been studied by excision of the posterior part of the rib cage at autopsy, followed by fixation, decalcification, section and staining. Injection of India ink was used to simulate local anaesthetic. At a point 7 cm from the midline, the distance from the posterior aspect of the rib to the pleura averaged 8 mm. The intercostal nerve usually comprises a number of small bundles without any enclosing fascial sheath. The bundles lie in a triangular space bounded by the rib, the posterior intercostal membrane and the intercostalis intima muscle. The first two appear impervious to the spread of an injected solution, but the last permits spread of the injection round the internal aspect of the rib to gain access to the intercostal spaces above and below that into which the injection has been made. An injection of 3 ml will also spread medially to enter the paravertebral space and surround the sympathetic chain. A small clinical study gave excellent analgesia after operation for a mean duration of 12.3 h following unilateral intercostal block with 3 ml of bupivacaine 0.5% (with adrenaline) into each of the intercostal spaces T5-11, before cholecystectomy through a subcostal incision. There were no complications in the series.

Rats were exposed to 100% oxygen for up to 60 h to determine early changes in lung permeability leading to the development of pulmonary edema. The time course of development of increased solute flux was assessed by the clearance of 99mTc-labeled diethylenetriamine pentaacetate (99mTc-DTPA) from the lung and the accumulation of 125I-labeled albumin (125I-albumin) in the lung. These end points were related to the development of pulmonary edema by the measurement of the wet-to-dry weight ratio of the lung and the weight of fluid in the pleural cavity. No significant changes occurred until 48 h of hyperoxia, when sharp increases in both indexes of lung permeability and wet-to-dry weight ratio occurred. By 60 h of exposure, pleural effusions had developed. The volume of this effusion was significantly correlated to both 99mTc-DTPA clearance and 125I-albumin flux.

The mean volume of the extrathoracic respiratory tract in six cadavers was found to be 72 ml (BTPS), (S.D. ±32). Expressed as a fraction of body weight in pounds this amounted to 0.55. The intrathoracic anatomical dead space was measured in three intubated subjects. The mean value was 66 ml (BPTS), (S.D. ±29) or 0.43 times the body weight in pounds. The influence of the position of the jaw on the dead space was studied in the six cadavers and three conscious subjects. Depression of the jaw with flexion of the neck produced a mean decrease in the dead space of 31.4 ml while a protrusion of the jaw with extension of the neck increased the dead space by 39.7 ml. Submitted on July 28, 1958

Twelve patients with severe chronic obstructive lung disease undergoing 15 operations were assessed with preoperative lung function tests and blood gas estimations. Their operative and postoperative course was followed. There were no deaths or serious complications. Patients fell into three groups: those with low respiratory capacity but normal blood gases, who required no special respiratory treatment apart from physiotherapy and antibiotics; those with hypoxaemia but normal arterial carbon dioxide pressure, who needed more prolonged oxygen treatment after operation; and those with hypoxaemia and hypercapnia, who needed postoperative ventilatory support. While forced expiratory volume in one second (FEV,) is a good screening test in preoperative assessment it should be supplemented by arterial blood gas estimations in patients with an FEV, of less than 1 litre.

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