Randomised comparative study in 217 women of three disposable plastic IUCD thread retrievers.

OBJECTIVE: To assess the relative efficacy of three disposable plastic instruments in the retrieval of 'missing' IUCD threads. DESIGN: A prospective randomised comparative single centre study. SETTING: Family Planning Clinic in London, UK. SUBJECTS: 217 of 350 IUCD users referred to the research team with 'missing' IUCD threads entered the study. INTERVENTION: All women initially underwent exploration of the endocervical canal with Spencer Wells forceps. When this procedure did not retrieve the threads, the patients were entered into the study. A maximum of two randomly chosen plastic IUCD thread retrievers were then used in any one patient to explore the uterine cavity and capture the 'missing' threads. The order in which the two retrievers were employed was also determined at random. Four separate entries into the uterine cavity were permitted with each instrument, the endocervical canal being explored with Spencer Wells forceps after each retraction of the instrument to identify the possible descent of the threads. MAIN OUTCOME MEASURES: Threads brought down beyond the external cervical os, or threads brought to within the endocervical canal and then grasped by Spencer Wells forceps. RESULTS: In approximately 40% of all patients, the threads were retrieved with Spencer Wells forceps alone and a further 40% with the disposable plastic retrievers. About 5% had no retrievable threads, and only 2.5% of the referred patients required general anaesthesia for removal of their IUCD. The analysis of the comparative trial was confined to the 197 patients with retrievable threads which could not be brought below the external os with Spencer Wells forceps. The first plastic retriever used was successful in 50% of patients. The Retrievette (59%) and the Emmett (53%) performed better than the Mi-Mark Helix (37%) in this study. The difference was statistically significant (P = 0.03) and the 95% confidence interval for the difference of the Mi-Mark Helix from the other two retrievers was 4% to 33%. This retrieval rate for the Mi-Mark Helix was much worse than in previously reported studies, though one doctor did have a better success rate with this retriever. The success rates, using a second plastic retriever randomly chosen from the two not used in the first attempt, were almost identical to those observed with the first retrievers: 63%, 56% and 36%. The success rate did not appear to be influenced by the length of thread, day of cycle, device type or parity. The success of the second retriever tried did not seem to be influenced by the retriever that had failed previously. CONCLUSIONS: Based on our experience, the initial exploration of the endocervical canal with Spencer Wells forceps is invaluable. If this simple manoeuvre fails to retrieve the 'missing' threads, either the Retrievette or the Emmett thread retrievers are useful tools in general practice or in the family planning clinic setting.

PIP: A group of 217 women of 350 IUD users with missing IUD threads were enrolled in the investigation. The final sample of the comparative trial involved 197 patients with retrievable threads which could not be brought below the external os with Spencer Wells forceps. 143 (73%) used Gravigard; 19 (10%) the Mini-Gravigard; 21 (10%) other copper-bearing devices (Multiload, Mini-Multiload, Novagard, Ortho-Gyne-T); and 12 (6%) the Lippes Loop, while in the remaining 2 (1%) the type of device was not recorded. The endocervical canal of all women was explored with a Spencer Wells forceps, and 2 randomly chosen plastic IUD thread retrievers were used to capture the missing threads. The threads were retrieved with Spencer Wells forceps alone in about 40% of patients, and with the disposable plastic retrievers in another 40%. About 5% had not retrievable threads, and only 2-5% of the patients required general anesthesia for IUD removal. The 1st plastic retriever succeeded in removing the device in 50% of patients. The Retrievette (59%) and the Emmett (53%) performed better than the Mi-Mark Helix (37%) yielding a statistically significant difference (P=0.03). The 95% confidence interval for the difference of the Mi-Mark Helix from the other 2 retrievers was 4% to 33%. The success rates of a 2nd plastic retriever randomly chosen from 2 retrievers not used in the 1st attempt were 63%, 56%, and 36%, analogous to rates with the 1st plastic retrievers. 33 of the 47 women in whom the plastic retrievers failed, had the threads/IUDS retrieved with a metal hook, preferably with the Birnberg hook. The initial exploration of the endocervical canal with Spencer Wells forceps proved valuable, and if it fails either the Retrievette or the Emmett thread retrievers are effective in general practice or in family planning clinics.

Carotid chemoreceptor response to increases in CO2 output.

The effect on carotid chemoreceptor activity of alterations in PaCO2 oscillations produced by venous CO2 loading via the small intestines was studied in anaesthetised cats, which were paralysed and ventilated at constant frequency. Changes in PaCO2 oscillations were assessed from continuously recorded oscillations of arterial pH. Chemoreceptor activity was averaged over 20-50 pH cycles to determine the amplitude (csnd ampl) and mean level (csnd mean) of the respiratory fluctuation in discharge frequency during control and CO2 loaded periods. Two groups of 5 cats were studied. In both groups, the amplitude of the PaCO2 oscillations increased by an overall average of 74.5% (standard error, SE = 9.2) with minimal change in mean PaCO2 (average increase 0.7 mm Hg), in response to an increase in VCO2 of 77.5% (SE = 7.4). When isoxia was maintained (Group 1) csnd ampl increased by 51.3% (SE = 11.1) and csnd mean by 17.3% (SE = 7.8). In Group 2, PaO2 rose by 16.7 mm Hg (SE = 1.5) during CO2 loading and both csnd ampl and csnd mean decreased by 7.4% (SE = 9.3) and 2.3% (SE = 13.3) respectively. The results demonstrate a sensitivity of chemoreceptors to changes in VCO2 which is influenced by small changes in PaO2.

Induction dose of propofol in children.

In a study of 144 children aged 1-12 years, attempts were made to assess the ED50 and ED90 of the intravenous induction agent, propofol. The doses required for loss of eyelash reflex and tolerance of facemask, in 50% of unpremedicated children, were 1.6 mg/kg and 2.5 mg/kg respectively. In children premedicated with oral trimeprazine the corresponding values of ED50 were 1.1 mg/kg and 2.0 mg/kg. Doses of 2.8 mg/kg in unpremedicated and 2.0 mg/kg for those who received trimeprazine were required for loss of eyelash reflex in 90% of children. This probably corresponds to an effective induction dose. Pain and movement on induction were common; the incidence was 27% and 21.5% respectively.

Effect of premedication on the induction dose of thiopentone in children.

The effective dose of thiopentone in 90% ( ED90 ) of unpremedicated children is 10.5 mg/kg. This is significantly greater (p less than 0.01) than in premedicated children. The ED90 in children premedicated with TDP (a mixture of trimeprazine , droperidol and physeptone with atropine) is 4.2 mg/kg which is significantly less (p less than 0.05) than with trimeprazine and atropine ( ED90 5.2 mg/kg) or papaveretum and hyoscine ( ED90 5.0 mg/kg).

The relation of age to the thickness of the interventricular septum, the posterior left ventricular wall and their ratio.

We obtained echocardiographic measurements of interventricular septal and posterior left ventricular wall thickness in 100 apparently normal subjects in whom there was no evidence or history of coronary artery disease, hypertension or prolapsing mitral valve. Subjects were divided into five age groups of 20-29, 30-39, 40-49, 50-59 and 60-70 years and there were 20 subjects in each group. Measurements of interventricular septum and posterior left ventricular wall thickness were made in each subject at both mitral and sub-mitral levels at the time of Q wave inscription, and the measurements were related to body surface area. The interventricular septum increased from a median of 8.3 mm in the age group 20-29 to 11.2 mm in the group 60-70, whereas the posterior left ventricular wall increased from 7.5 mm to 9.8 mm. The difference in the medians between the groups 20-29 and 60-70 was statistically significant for both interventricular septum and posterior left ventricular wall (P less than 0.02). Our data showed that interventricular septal, posterior left ventricular wall thickness measurements and their ratio should be related to age in order to assess their significance.

Influence of age on response to ipratropium and salbutamol in asthma.

We studied the differential response to inhaled salbutamol and ipratropium of 29 asthmatic patients, 18 intrinsic, 11 extrinsic, using peak expiratory flow rate (PEFR), forced expiratory volume in one second (FEV1), and forced vital capacity (FVC). Thirty minutes after a theoretically maximally bronchodilating dose of salbutamol (400 microgram) or ipratropium (80 microgram), second doses frequently caused further bronchodilatation. We suspect that second doses may reach bronchi untouched by the first inhalation. Analysis of variance showed a powerful intrinsic versus extrinsic effect, and there were clearly differences between patients in their response to treatment (patient versus drug interaction) but these differences were not removed by dividing the patients into intrinsic and extrinsic groups. Results for the group as a whole favoured salbutamol, but examination of individual results by a pattern-recognition technique showed ipratropium equally effective in eight patients and more effective in three. All patients with a definite predominant salbutamol response were less than 40 years old. The response to salbutamol declined significantly with age, whereas that to ipratropium did not. In general in patients aged less than 40 years salbutamol is the drug of choice. With advancing age, and the apparent decline of beta-adrenergic responsiveness, the initially comparatively small response to ipratropium becomes relatively more important and may predominate. In older patients ipratropium, or continued therapy with both drugs, may be preferable.

Birth weight standards in a community of mixed racial origin.

A prospective study of approximately 2000 consecutive deliveries at a north London hospital, with a mixed population distribution of Caucasian, British and Irish, Indian and West Indian mothers was made between May 1975 and August 1976. Most of the results are based on 1322 births of known gestational age. Babies of Indian mothers were found to be approximately 300 g lighter than their Caucasian equivalents at term, and by United Kingdom birth weight standards, 15 per cent of the babies of Indian mothers were below the fifth centile. Birth weights of babies of West Indian mothers ranged between those of the Indian and the Caucasians.