EFFECTS OF PROLONGED NITROUS OXIDE ON WOUND HEALING

The effect of long-term nitrous oxide treatment on wound healingwas assessed in rats using wound tensiometry, to assess woundstrength in surgical incised wounds, and estimation of the rateof healing of a small area of full thickness skin loss. No effecton wound strength could be detected in animals treated for threedays with 25 or 60 per cent nitrous oxide. Similarly, no significantdifference was present in the rate of healing of the area offull thickness skin loss after two days treatment with nitrousoxide.     

Anaesthetic pollution in the dental out-patient surgery

Five factors influencing pollution in the dental surgery are considered. Despite leakage from round the mask and from the mouth, scavenging can remove the majority of expired anaesthetic. The effectiveness of scavenging can usefully be monitored with a Wright respirometer. Spillage of anaesthetic vapour at induction and at the end of anaesthesia must be avoided. In addition to scavenging, pollution levels are minimised if a Boyle's type machine is used and excessive fresh gas flow avoided. Room ventilation, e.g. extract fans in windows, is vital in reducing pollution levels in the surgery. Room size and non-uniformity of ventilation must also be considered.     

The Sustained Action of Erythropoietin Injected Repeatedly into Rats and Mice

Rats and mice were given exogenous erythropoietin for periods from 40to over 200 days. Increased erythropoiesis was maintained as long as erythropoietin was given; when it was stopped, erythropoiesis returned to its normallevel; when the dose was dimished, erythropoiesis fell accordingly.

In mice there was no long-term increase of platelets or change in the differential leukocyte counts and leukocyte counts were, during the middle period of the experiment, decreased.

One mouse developed a tumor. It is pointed out that humans with certainchronic anemias have lived for years with greatly elevated concentrations oferythropoietin in their blood and urine, yet they have normal leukocyte andplatelet counts and no tumors.

Submitted on May 6, 1963 Accepted on July 8, 1963