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Biomedical subjects

J Dingley

Publications and source records attributed to J Dingley.

18 recordsLinked to original sources
PubMed2000

Use of nitric oxide for decompensated right ventricular failure and circulatory shock after cardiac arrest.

We describe a case of peri-operative cardiac arrest, severe right ventricular failure and pulmonary hypertension in a 60-yr-old woman with interstitial pulmonary fibrosis. Inhaled nitric oxide therapy rapidly improved arterial oxygenation and haemodynamic variables, allowing recovery and weaning from mechanical ventilation. Subsequently, the patient was discharged from the cardiac intensive care unit.

Anesthesia, General↗
PubMed1999

Blood volume determination by the carbon monoxide method using a new delivery system: accuracy in critically ill humans and precision in an animal model.

OBJECTIVE: To evaluate accuracy and repeatability of blood volume determinations made by the carbon monoxide method, using a ventilator-driven administration system. DESIGN: Prospective within-patient comparison, using simultaneous measurements by two methods to determine accuracy. Prospective laboratory investigation in animals to estimate repeatability. SUBJECTS: For accuracy: Nineteen ventilated critically ill patients in a university hospital intensive care unit. For repeatability: Six anesthetized, mechanically ventilated normovolemic pigs because this is impossible to perform in humans. INTERVENTIONS: In the accuracy study, a small mass of carbon monoxide was administered via a closed breathing system and arterial blood samples were taken from existing cannulas. In the repeatability study, an intramuscular sedative was given, followed by an inhalational anesthetic induction and mechanical ventilation via a tracheal tube. Left axillary artery and external jugular vein cannulas were sited. Anesthesia was maintained using an intravenous infusion. Five sequential circulating hemoglobin and blood volume estimations were made using the carbon monoxide method. MEASUREMENTS AND MAIN RESULTS: The small carboxyhemoglobin increase produced by uptake of a small, known mass of carbon monoxide was used to estimate the circulating blood volume. Simultaneous measurement, using 51Cr-labeled red blood cells, was performed. Twenty measurements were made in 19 patients. The bias (mean difference between blood volume measurements by the two methods) was 397 mL (5.53 mL x kg(-1)) +/-415 mL (+/-5.95 mL x kg(-1)); the limits of agreement (mean difference +/-2 SD) were -433 mL and 1227 mL (-6.36 mL x kg(-1) and 17.42 mL x kg(-1)). Therefore, 95% of expected differences will lie between these limits. The mean blood volume was 75.8 mL x kg(-1) in the animals. The coefficient of variation of repeated estimates was 9.49%. Mean circulating hemoglobin mass was 7.31 mmol with a coefficient of variation of 10.18%. The mean hemoglobin concentration, by co-oximetry, was 5.014 mmol x L(-1), coefficient of variation, 2.99%. CONCLUSION: This arrangement is a potential bedside method of estimating blood volume and circulating hemoglobin mass. We have rendered the technique more acceptable clinically by creating a ventilator-driven administration system.

Administration, Inhalation↗
PubMed1997

Ease of insertion of the laryngeal mask airway by inexperienced personnel when using an introducer.

The Portex introducer for the laryngeal mask airway was designed as an aid to successful insertion, acting as an idealised 'artificial hard palate' to guide the tip of the laryngeal mask into the correct position. A number of authors have investigated laryngeal mask insertion by unskilled personnel in certain situations, one example being nurses during in-hospital cardiopulmonary resuscitation. We investigated whether the introducer had any effect on the incidence of first-time successful LMA placement by unskilled personnel. These were nonanaesthetist doctors, randomly assigned to have one attempt at LMA insertion in an anaesthetised patient, with and without the introducer. In 44 patients with the LMA being inserted according to the manufacturer's instructions, there was a 68% success rate (14 failures). In 45 patients with the LMA being inserted with the aid of a Portex introducer, there was a 96% success rate (two failures). This was a highly significant improvement (p < 0.001).

Adolescent↗
PubMed1996

A computer-aided comparative study of progressive alertness changes in nurses working two different night-shift rotas.

Two groups of nurses were investigated during the course of two different types of night-shift rota. The purpose was to define, if possible, the optimum shift pattern for hospital night staff. The mental alertness of two groups of nurses was assessed, both subjectively and objectively, at the beginning and end of each night-shift of a set of nights being worked. Alertness was assessed subjectively by means of a visual analogue scale, and objectively by means of a computer generated test, the unprepared simple reaction time task. One group worked permanent nights and the other rapidly rotating nights. Subjectively the nurses felt they were more alert at the beginning than at the end of a night-shift, and also at the beginning of a span of nights than at the end. With computer testing, performance was broadly worse at the beginning of a shift than at the end. It was worse at the beginning of a span of nights, improving to a peak at around the fourth day, and then in the case of permanent nights, remaining about the same or deteriorating slightly towards the end of the span. The improvement by day 4 could be a practice effect or it may be that it takes this long to adjust to the new pattern of working as some authors have described. Debate centres around whether nurses should cease working nights just as they have become accustomed to them as in the rapid rotation, or continue for longer to gain benefit from this acclimatization as in permanent nights.

Analysis of Variance↗
PubMed1996

The use of bromothymol blue and sodium thiopentone to confirm tracheal intubation.

The possibility of using chemical changes to confirm correct tracheal tube placement was investigated with a view to their use in developing countries where more sophisticated methods are unavailable. The effect of bubbling expired gases through a 10% solution of bromothymol blue and a 0.25% solution of thiopentone led to chemical changes producing, in the case of bromothymol blue, a colour change and in that of thiopentone, precipitation, probably due to a change in pH caused by carbon dioxide. We also discovered that the time to precipitation of the thiopentone could be greatly reduced if it was mixed with a precise quantity of lignocaine. These simple end points can reliably confirm the correct placement of a tracheal tube at least as rapidly as the correct use of capnography.

Adult↗
PubMed1996

The use of a non-invasive method to measure intrapulmonary shunt during one-lung anaesthesia.

The Non Invasive Virtual Shunt computer program has previously been described and validated. The system has subsequently been developed to give a real time, continuous trace of virtual shunt. A portable computer connected to routine monitoring equipment displays a plot of virtual shunt updated every 10 s. A practical use of this device in the clinical setting of one-lung anaesthesia is described. The equipment was used to monitor shunt before, during and after surgery in three patients. In one case, a displaced double lumen bronchial tube was detected before there was any other indication of the problem.

Adult↗
PubMed1996

Insertion methods of the laryngeal mask airway. A survey of current practice in Wales.

The efficacy of the laryngeal mask is widely accepted, but there is a lack of consensus on the best insertion method and on the use of the mask for certain surgical procedures. We sent a questionnaire to all anaesthetists in Wales to discover the frequency of use of the laryngeal mask and the preferred insertion method. The questionnaire also enquired about the use of the laryngeal mask during anaesthesia for laparoscopic clip sterilisation. Replies were received from 125 consultants (89% of those circulated) and 122 non-consultants (69%). The insertion method described in the manufacturer's instruction manual was preferred by 30% of consultants and 34% of the others. The next most popular option was insertion of the mask with the cuff partially inflated. Twenty-three per cent of consultants and 34% of non-consultants were prepared to use the laryngeal mask during anaesthesia for laparoscopic clip sterilisation. Although the insertion technique described in the instruction manual is the most widely employed, a large number of alternative methods are frequently used.

Anesthesia↗
PubMed1995

Interferon alfa for chronic active hepatitis B. Long term follow-up of 62 patients: outcomes and predictors of response.

OBJECTIVE: To evaluate the response to treatment with interferon alfa and the long term outcome of patients with chronic active hepatitis B. METHODS: Sixty-two patients with chronic active hepatitis B (43 males, 19 females; age range, 10-67 years) who were treated with interferon alfa at Westmead Hospital between 1984 and 1992 were followed up (mean period of follow-up, 44 months). Thirty-nine patients were treated with interferon alfa-2a and 23 with interferon alfa-2b for a mean of 22.5 weeks. Interferon was given three times a week with a dose range of 3-21 million U. We evaluated pretreatment predictors of response (patient's age, sex, ethnic origin, presence of cirrhosis, serum levels of alanine aminotransferase [ALT] and hepatitis B virus DNA [HBV-DNA]) and the effect of dose and type of interferon. RESULTS: Nine patients had a complete response to treatment with interferon alfa (loss of hepatitis B surface antigen), 26 had a partial response (permanently HBV-DNA negative, hepatitis B e antigen to anti-hepatitis Be seroconversion), eight had a transient response and 19 had no response. All patients with a complete response had normal ALT levels at last follow-up. Histological evidence of hepatic inflammation was significantly reduced in responders. A high pretreatment ALT level and a low HBV-DNA titre were both positive predictors of a favourable response. We found no significant difference in the response to different types of interferon or to high or low dose regimens, or in the responses of patients with cirrhosis. CONCLUSION: Treatment with interferon alfa was associated with prolonged suppression of HBV replication in over half these patients and 14% appear to have been cured of the infection. Suppression of HBV replication is associated with sustained abatement of liver disease.

Adult↗
PubMed1994

A comparative study of the incidence of sore throat with the laryngeal mask airway.

In a prospective study of 150 patients randomly assigned to three groups, we have compared the incidence and duration of sore throat after a standard anaesthetic regimen using three different methods of airway management: facemask; laryngeal mask, and laryngeal mask with insertion aid. The insertion aid is currently being developed by Portex Ltd and is intended both to facilitate accurate placement of the laryngeal mask and to reduce trauma during insertion. All the patients were women undergoing short operative procedures requiring minimal postoperative analgesia. The incidence of sore throat was significantly less with a facemask (8%) than with the laryngeal mask when used without the insertion aid (28.5%) (p < 0.02). When using the insertion aid the incidence was 18% and this was not statistically different from the facemask. The presence of blood on the laryngeal mask (22%) was less likely when the insertion aid was used (4%) (p < 0.02).

Adult↗