Biomedical subjects
Publications and source records attributed to T G Dow.
Gastric (GP) and lower oesophageal sphincter pressures (LOSP) were measured in non-pregnant female volunteers (group I) and pregnant women with (group III) or without (group II) heartburn. Patients in early pregnancy had greater gastric pressures than group I. Mean barrier pressure (LOSP-GP) was significantly decreased in pregnant patients complaining of heartburn (group III) compared with groups I and II.
Although heartburn, thought to indicate reflux of gastric contents into the oesophagus, occurs frequently in pregnant women during the last trimester, its aetiology is not clear. Prolactin blood concentrations rise progressively during pregnancy and heartburn is known to disappear spontaneously during the last weeks of pregnancy. In view of this and other factors, motility studies and estimation of serum prolactin levels were carried out on 20 pregnant Black women. Results show that patients with prolactin levels over 3,000 microunits/ml had significantly higher mean barrier presures (sphincter pressure-gastric pressure) than the patients with hormone levels of less than 3,000 microunits/ml (P less than 0,02). No direct correlation could, however, be demonstrated between barrier pressures and prolactin levels (r = 0,3494). It is concluded that further studies would seem to be indicated on an animal model to establish the importance of prolactin in the regulation of the lower oesophageal sphincter tone.
Intraluminal gastroesophageal pressure and pH studies have been performed on 8 nonpregnant women, 10 pregnant women with heartburn, and 10 pregnant women without heartburn. Each patient was tested under resting conditions and after intravenous injection of 0.6 mg atropine. In both groups of pregnant patients the intragastric pressure was found to be higher than that of the nonpregnant subjects. The stomach to lower esophageal sphincter pressure (LESP) gradient under resting conditions was least in the pregnant patients with heartburn. After the administration of atropine, a fall in the LESP occurred in all 3 groups of patients which was most profound in the nonpregnant subjects and in the pregnant patients without heartburn. These changes and the pH recordings of the lower esophagus indicate the adverse effect that atropine has on the competency of the LESP both in pregnancy and in the nonpregnant state. Atropine should therefore be used with caution as a premedicant and preferably combined with metoclopramide (Maxolon).
The effects of intravenous metoclopramide (Maxolon) on the lower oesophageal sphincter (LOS) were studied in three groups of patients, one group being normal control and the other two being pregnant females, one without heartburn and the other with. Metoclopramide increases the LOS pressure 20.5, 15.2 and 10.2 cm H2O respectively (p less than 0.005, p less than 0.005 and p less than 0.05). These findings suggest that for patients undergoing elective or emergency obstetrical anaesthesia, intravenous metoclopramide may help reduce the incidence of regurgitation of gastric contents.
The effects of intravenous hyoscine 0-4 mg and atropine 0-6 mg on lower oesophageal sphincter tone were studied in normal human subjects. Hyoscine and atropine both decreased the lower oesophageal sphincter (L.O.S) pressure by approximately 11 cm H2O (p less than 0-01). There was also an increased incidence of reflux as seen by an indwelling pH electrode in the lower oesophagus. These findings are relevant to the preoperative preparation of patients presenting for emergency obstetrical anaesthesia; since gastro-oesophagus reflux and pulmonary aspiration of acid gastric content continues to be a significant cause of morbidity and mortality.
A significantly greater rise in carboxyhaemoglobin concentration in response to smoking a single cigarette was shown in pregnant (3-9% increase) as opposed to non-pregnant (2-1% increase) women. This was more pronounced when anaemia was present (5-0% increase) and appeared to be inversely related to the haemoglobin concentration. We suggest that the risks to the fetus may be particularly increased when anaemia complicates pregnancy in women who smoke cigarettes.
Serum concentration of radioimmunoreactive gastrin reflects closely the known physiology of gastric acid secretion during pregnancy. In particular, marked rises of immunoreactive gastrin occur in late pregnancy, at parturition, and in the early puerperium.