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Biomedical subjects

S M Yentis

Publications and source records attributed to S M Yentis.

At least 19 recordsLinked to original sources
PubMed2003

The effect of neuromuscular blockade on the efficiency of mask ventilation of the lungs.

We conducted a two-part study to assess the practice of withholding neuromuscular blockade until the ability to ventilate the lungs using a bag and face mask (mask ventilation) has been established following induction of anaesthesia. The first part of the study consisted of a postal survey (71% response rate) of 188 anaesthetists in the Oxford region to assess their current practice. Thirty per cent of respondents always checked mask ventilation before administering a neuromuscular blocking drug, whereas 39% of respondents (all them consultants) never did this. A further 31% only did so in the case of known or anticipated difficulty with the airway. In the second part of the study, we measured inspired (V(TI)) and expired (V(TE)) tidal volumes before and after neuromuscular blockade in 30 patients undergoing general anaesthesia. The ratio V(TE)/V(TI) was used as a measure of the efficiency of ventilation. There was no difference in V(TE)/V(TI) before [mean (SD) 0.47 (0.13)] and after [0.45 (0.13)] neuromuscular blockade. We conclude that neuromuscular blockade does not affect the efficiency of mask ventilation in patients with normal airways.

Adolescent↗
PubMed2003

Use of the bougie in simulated difficult intubation. 1. Comparison of the single-use bougie with the fibrescope.

We studied the success rates for tracheal intubation in 64 healthy patients during simulated grade III laryngoscopy after induction of anaesthesia, using either the single-use bougie or oral flexible intubating fibrescope, both in conjunction with conventional Macintosh laryngoscopy. Patients were randomly allocated to either simulated grade IIIa or grade IIIb laryngoscopy, and also to one of the two study devices. Success rates for tracheal intubation (primary outcome measure) and times taken to achieve intubation (secondary outcome measure) were recorded. For the simulated grade IIIa laryngoscopy group, the fibreoptic scope was more successful than the bougie (16/16 successful intubations vs. 8/16; p = 0.02). For the simulated grade IIIb laryngoscopy group, the fibreoptic scope was also more successful than the bougie (8/16 successful intubations vs. 1/16; p = 0.02), but clearly use of the fibreoptic scope was not as successful as it had been in simulated grade IIIa laryngoscopy (p = 0.04). With either device, median (range) total tracheal intubation times for successful attempts with either grade of laryngoscopy were less than 60 s (19-109) and there were no clinically important differences. We conclude that the fibrescope used in conjunction with Macintosh laryngoscopy is a more reliable method of tracheal intubation than the single-use bougie in both types of grade III laryngoscopy. This finding has implications for the management of patients in whom grade III laryngoscopy is encountered unexpectedly after induction of anaesthesia, and also for the management of patients previously known to have grade III view at laryngoscopy.

Adolescent↗
PubMed2003

Use of the bougie in simulated difficult intubation. 2. Comparison of single-use bougie with multiple-use bougie.

We studied the success rates for tracheal intubation in 32 healthy, anaesthetised patients during simulated grade IIIa laryngoscopy, randomised to either the multiple-use or the single-use bougie. Success rates (primary end-point) and times taken (secondary end-point) to achieve tracheal intubation were recorded. The multiple-use bougie was more successful than the single-use one (15/16 successful intubations vs. 9/16; p = 0.03). With either device, median [range] total tracheal intubation times for successful attempts were < 54 [24-84] s and there were no clinically important differences between these times. We conclude that the multiple-use bougie is a more reliable aid to tracheal intubation than the single-use introducer in grade IIIa laryngoscopy.

Adolescent↗
PubMed2003

Assessment of the effect upon maternal knowledge of an information leaflet about pain relief in labour.

Pregnant women were randomly assigned to receive, at booking, the usual written information pack either with or without the Obstetric Anaesthetists' Association's (OAA's) leaflet 'Pain Relief in Labour'. At 36 weeks' gestation, a structured interview was conducted at which we assessed the sources of information the women had used and their knowledge of specific aspects of obstetric analgesia and anaesthesia described in the OAA leaflet. The most useful sources of information overall were friends, family, midwives, books and information leaflets (no significant difference between the groups); 72% of all women felt they had received adequate information although 70% said they would have liked to have discussed methods of analgesia with an anaesthetist before delivery. Parturients allocated to receive the leaflet (n = 37) were more knowledgeable than those who received only standard booking information (n = 39) about all analgesic and anaesthetic techniques except for systemic pethidine, although this difference in knowledge only reached statistical significance for extending epidural analgesia for emergency Caesarean section. We conclude that the OAA leaflet improves women's knowledge of analgesic techniques and suggest that all information of this type be formally assessed in this manner; furthermore given the practical difficulties in conducting studies of this type, the latter should be adequately resourced, perhaps by the bodies that issue such leaflets.

Analgesia, Obstetrical↗
PubMed2003

Effect of the Confidential Enquiries into Maternal Deaths on the use of Syntocinon at Caesarean section in the UK.

The recommended dose of Syntocinon used for uterine contraction at Caesarean section is5 units intravenously, given slowly. We conducted a survey of the use of Syntocinon at Caesarean section among 240 lead obstetric anaesthetists in the UK in 2001 and found that 155 (87%) of the 179 (75%) respondents gave 10 units, 77 of them (50%) by rapid bolus. The risks of Syntocinon, especially given by rapid injection, were highlighted in the report of the Confidential Enquiries into Maternal Deaths in the UK (1997-99), which was published at the end of 2001, and so the survey was repeated in 2002. Of the 256 forms sent, 198 completed replies were returned (77%); these indicated a dramatic change of practice: only 30 (15%) now gave 10 units and only 7 of these (23%) by a rapid injection. One hundred and sixty-seven respondents to the second survey (84%) stated they had changed their practice and 159 of these (95%) gave the Confidential Enquiries report as the main reason for change. These results highlight the importance of the Confidential Enquiries as a means of improving practice.

Anesthesia, Obstetrical↗
PubMed2002

Obstetric anaesthetists' workload.

The current recommendation of one consultant session per 500 deliveries with full sessional cover for units over 3000 deliveries is arbitrary and is not based on workload. The Audit Commission has questioned the wide variability of anaesthetic staffing on labour wards. The aim of this study was to investigate whether there is a relationship between current workload and obstetric anaesthetic staffing in five maternity units. In 1998, a 2-week diary of workload in the participating obstetric units was assessed in terms of staffing and clinical and nonclinical activities. The busiest time was 08:00 to 12:30. The working patterns between consultants and trainees varied considerably. Time spent on nonclinical activity by consultants averaged 51%. Any calculation of consultant sessions will need to take into account nonclinical activities. Other factors requiring consideration are the number of high-risk cases, as well as the number and experience of trainees.

Anesthesiology↗
PubMed2002

Glycopyrronium and hypotension following combined spinal-epidural anaesthesia for elective Caesarean section in women with relative bradycardia.

The ability of glycopyrronium to reduce the severity of hypotension following subarachnoid block in parturients with a relative bradycardia was evaluated in a double-blind randomised controlled study. Women with a resting heart rate of < or = 80 beat x min(-1) presenting for elective Caesarean section were randomly allocated to receive either glycopyrronium 2 microg x kg(-1) or normal saline intravenously once positioned for combined spinal-epidural anaesthesia. Following spinal injection of 2.6 ml hyperbaric bupivacaine 0.5% and fentanyl 15 microg, women randomly allocated to the saline group were given 6 mg ephedrine so that all parturients received some prophylaxis against hypotension other than the fluid preload. Further ephedrine and fluid boluses were administered if mean arterial pressure fell 20% or more from resting values. Using a sequential analysis technique, analysis after the first 20 subjects indicated the study should be stopped, with no difference in ephedrine requirements or hypotension between the groups. We conclude that pretreatment with glycopyrronium 2 microg x kg(-1) is no more effective than 6 mg ephedrine in preventing hypotension following subarachnoid block in parturients with relatively low resting heart rates.

Adult↗
PubMed2002

Attitudes of patients and anaesthetists to informed consent for specialist airway techniques.

We investigated the attitudes of 96 patients and 163 anaesthetists to the need for obtaining informed consent before specialist airway techniques. Participants were asked to score six questions using a numerical scale, as to whether they thought consent was necessary before specific procedures, particularly in relation to fibreoptic intubation used for teaching or maintaining skills. Significant differences in opinion were found between patients and anaesthetists despite a wide range of views. Overall, patients felt that specific consent was required for non-routine techniques, whilst anaesthetic respondents felt this was unnecessary, even if teaching. We conclude that guidance in obtaining consent is needed to support anaesthetists wishing to practice or teach fibreoptic intubation.

Adult↗
PubMed2002

Training in airway management.

Management of the airway is central to the practice of anaesthesia, yet trainees frequently feel poorly trained in this area. A large range of skills needs to be acquired, but there are often problems providing training on live patients. We review the different modalities available for training and assessment in airway management.

Anesthesiology↗
PubMed2001

Maternal anti-factor Xa activity following subcutaneous unfractionated heparin after Caesarean section.

Unfractionated heparin is widely used for prophylaxis against venous thromboembolism after Caesarean section. We performed a survey of thromboprophylactic methods after elective Caesarean section in 50 maternity units in the United Kingdom. We found that a variety of regimens were used. Thirteen (26%) used subcutaneous unfractionated heparin at standard (non-pregnant) doses. We then studied anti-Xa activity in women following elective Caesarean section under regional anaesthesia. Initially, eight women were given 5000 U unfractionated heparin subcutaneously after surgery and anti-Xa activity was measured 1, 2, 3, 4, 5, 6, 8 and 10 h after administration. There was no detectable anti-Xa activity in any of the samples so the dose was increased to 7500 U in a further five women and a single anti-Xa assay performed at 3 h when peak activity should occur. Again, no activity was detected so the dose was increased to 10 000 U heparin in a final group of 10 women and anti-Xa activity measured at 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h. Although there was some activity after 10 000 U heparin, the level was below that accepted for prophylaxis. If anti-Xa activity is an appropriate monitor of prophylactic unfractionated heparin, doses up to 10 000 U are inadequate. Since there is evidence that enoxaparin is effective at producing adequate prophylactic anti-Xa activity following Caesarean section, we suggest abandoning the use of unfractionated heparin in favour of enoxaparin for this purpose.

Adult↗
PubMed2000

A comparison of the intubating laryngeal mask tracheal tube with a standard tracheal tube for fibreoptic intubation.

We conducted a prospective randomised study to compare the intubating laryngeal mask tracheal tube with a standard tube, for ease of tracheal intubation over a fibrescope. Thirty-six patients were investigated, using a sequential analysis technique. Ease of intubation was improved when the intubating laryngeal mask tracheal tube was used compared with the standard tube (p = 0.0009). Median (interquartile range [range]) intubation times (time from the tube's tip being level with the patient's teeth to successful placement) were 1.5 (1-2.3 [1-3]) s when the intubating laryngeal mask tracheal tube was used and 5 (3-7.3 [3-13]) s when the standard tube was used (p < 0.0001).

Adolescent↗
PubMed2000

Anti-infective measures and Entonox equipment: a survey.

We surveyed 102 maternity suites to investigate whether the guidelines of the Association of Anaesthetists of Great Britain and Ireland, for the use of anti-infective filters or fully disposable anaesthetic breathing systems for each patient, were being followed with regard to Entonox equipment on labour wards. Of 100 units giving information (98%), only seven used filters and only two replaced tubing between cases. Our survey shows that the recommended policy is not being applied to Entonox apparatus in delivery suites.

Anesthetics, Inhalation↗
PubMed2000

The effect of facial hair and sex on the dispersal of bacteria below a masked subject.

Surgical face masks prevent the dispersal of bacteria from the upper airway to surfaces immediately in front of and below the face during talking. However, mask wiggling has been reported to increase dermabrasion and bacterial contamination of surfaces immediately below the face. Facial hair and recent shaving may alter the quantity of particles shed by dermabrasion when the mask is wiggled. We investigated the effect of mask wiggling in 10 bearded and 10 clean-shaven male subjects, and 10 female subjects. Wiggling the mask significantly increased the degree of bacterial shedding onto agar plates 15 cm below the lips in bearded males (p = 0.03) and females (p = 0.03), but not in clean-shaven males. At rest without mask wiggling the bearded subjects shed significantly more bacteria than clean-shaven males (p = 0.01) or females (p = 0.001). To reduce the risks of contamination of the sterile field when face masks are worn females and bearded males should avoid wiggling the face mask. Bearded males may also consider removing their beards.

Colony Count, Microbial↗