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Biomedical subjects

M Popat

Publications and source records attributed to M Popat.

At least 19 recordsLinked to original sources

Insertion of the double lumen tube in the difficult airway.

Isolation of a lung and one-lung ventilation are commonly used during thoracic surgery. Insertion of double lumen tubes requires considerable skill and may be especially challenging in the difficult airway. We describe a method of inserting double lumen tubes in two patients with known difficult airways. This technique involves awake nasotracheal intubation followed by insertion of an oral double lumen tube under general anaesthesia.

Adult↗

Antenatal anaesthetic assessment of high-risk pregnancy: a survey of UK practice.

BACKGROUND: Anaesthetists are frequently involved in the management of high-risk pregnancy. Antenatal referral permits time to prepare an appropriate management plan for labour and delivery. This survey looked at current methods of referral in the UK and the role of a formal clinic. METHOD: A postal questionnaire was sent to lead consultant anaesthetists of 256 UK obstetric units enquiring into methods of referral for high-risk pregnancy. RESULTS: Replies were received from 196 units (response rate 77%). Only 30% of units that responded ran a formal anaesthetic pre-assessment clinic, the remaining 70% relying on ad hoc referrals of high-risk cases. Larger units were more likely to run formal clinics. Some units wishing to introduce a formal clinic had not been able to do so because of financial constraints. CONCLUSION: Most hospitals were satisfied with current arrangements for referral of high-risk pregnancy. A mechanism for anaesthetic referral of high-risk pregnancy is vital, but in many units is not via a formal clinic.

Adult↗

Ease of insertion of the laryngeal tube during manual-in-line neck stabilisation.

The laryngeal tube has a potential role in airway management during anaesthesia or cardiopulmonary resuscitation. In patients with unstable necks, the head and neck may need to be stabilised manually (manual in-line stabilisation), but it is not known whether this procedure affects the ease of insertion of the laryngeal tube. We studied, in a cross-over study, 21 adult patients to compare the success rate of ventilation through the laryngeal tube between the Magill position (a pillow under the occiput and the head extended) or the manual in-line position of the head and neck (without a pillow under the occiput). After induction of anaesthesia and neuromuscular blockade, the laryngeal tube was inserted in turn in the two positions. The ease of insertion was scored with four categories (easy, moderately difficult, difficult and impossible), and adequacy of ventilation through the device was assessed. Ventilation was adequate in all 21 patients in the Magill position, but only in two of 21 patients during manual in-line positioning (p < 0.01; 95%CI for difference: 68-94%). In the Magill position, insertion of the laryngeal tube was easy in 16 patients and moderately difficult in the remaining five patients; in the manual in-line stabilisation position, insertion was moderately difficult in two patients and impossible in the remaining 19 patients. Stabilisation of the patient's head and neck by the manual in-line method made insertion of the laryngeal tube either difficult or impossible.

Adolescent↗

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↗

Combined spinal epidural anaesthesia for caesarean section: a randomised comparison of Oxford, lateral and sitting positions.

Maternal position during induction of intrathecal anaesthesia for caesarean section influences block height and haemodynamic stability. In a randomised study of 90 women presenting for elective caesarean section using combined spinal-epidural anaesthesia, three positions were compared--the Oxford position (group O), the right lateral to supine wedged (group R) and the sitting to supine wedged (group S). Hyperbaric bupivacaine 12.5 mg with fentanyl 12.5 microg was injected intrathecally using a needle-through-needle CSE technique. Intravenous ephedrine 6 mg was given every minute that systolic blood pressure fell below 80% of baseline. Time required for block height to reach T5 as assessed by light touch, was similar in the three groups. There were no significant differences in blood pressure although ephedrine requirements were less in group R. There were no significant differences in the incidence of maternal nausea and vomiting or in neonatal outcome as assessed by Apgar scores and umbilical cord blood gas analysis. Although the study failed to show any significant differences in block height between the groups, no women in group O had a block above T2 compared with three in group R and three in group S.

Clinical Trial↗

A comparison of bupivacaine-fentanyl-morphine with bupivacaine-fentanyl-diamorphine for caesarean section under spinal anaesthesia.

In a randomised double-blind trial, postoperative analgesia and side effects of intrathecal morphine 0.1 mg and intrathecal diamorphine 0.25 mg were compared. Sixty women were randomised to receive intrathecal injection of 12.5 mg hyperbaric bupivacaine and 12.5 microg fentanyl with either morphine 0.1 mg (group M), or diamorphine 0.25 mg (group D). All women received 100 mg diclofenac rectally at the end of surgery and were given intravenous morphine via a patient controlled analgesia (PCA) system. Pain, PCA morphine usage and side effects were assessed at 2, 4, 8 and 24 h after spinal anaesthesia. The two groups were comparable for quality of intraoperative analgesia. There were no significant differences between the groups in time to first PCA demand, morphine consumption or oral analgesic use in each time period. Significantly more patients in group M were nauseated at 4 h whilst at 24 h nausea was significantly worse in group D. There was no significant difference between the groups in the number of women vomiting in the 24-h period. The two groups were comparable for pruritus and drowsiness. We conclude that 0.25 mg subarachnoid diamorphine is a suitable alternative to 0.1 mg morphine for post caesarean section analgesia.

Clinical Trial↗

Management of accidental dural puncture in labour with intrathecal catheters: an analysis of 10 years' experience.

The records of 15030 labour epidural blocks were analysed. Seventy-two accidental dural punctures (ADP) were recognised at the time of the procedure. In 34 women an epidural catheter was inserted intrathecally through the Tuohy needle and continuous spinal analgesia provided. In a further 37 women the primary management of ADP was to resite an epidural catheter. One woman who received a microspinal catheter later in labour was excluded from analysis. There were no significant differences in maternal characteristics, quality of labour analgesia and anaesthesia, or mode of delivery between the groups. Three repeat ADPs occurred during attempts to resite the epidural. Two women developed high blocks after epidural resiting, one of whom required intubation and ventilation. There was one high block in the intrathecal catheter group. The incidence of postdural puncture headache was 71% in the intrathecal catheter group compared with 81% in the non-intrathecal catheter group (P = 0.45). Epidural blood patch was performed on 50% of women managed with intrathecal catheters compared with 73% of those managed without (P = 0.08). Following ADP in labour an intrathecal catheter is a simple and effective alternative to resiting an epidural. Recognition of ADP is important as it allows appropriate management avoiding possible complications of administering epidural top-ups in the presence of a dural tear.

Journal Article↗

Failed intubation in a parturient with spina bifida.

We describe a case of unexpected difficult intubation and ventilation during induction of general anaesthesia for caesarean section. This case was particularly challenging as the parturient suffered with particularly severe cord tethering following surgery for spina bifida as a child. The observed change in anticipated intubation difficulty during pregnancy, and the use of the laryngeal mask airway as a life-saving device in obstetrics are described. Consideration of the difficulties of anaesthetising the patient with spina bifida for caesarean section in general, and the issues relevant in deciding whether to continue with surgery or to wake the patient up in particular are discussed. Suggestions are made for the management of this emergency situation in those not skilled in fibreoptic intubation.

Journal Article↗

Oxford positioning technique improves haemodynamic stability and predictability of block height of spinal anaesthesia for elective caesarean section.

A novel positioning technique was tested to see whether the unpredictability of block height and haemodynamic instability during spinal anaesthesia for caesarean section could be reduced. In this 'Oxford' position, the woman is placed left lateral with an inflated bag under the shoulder and pillows supporting the head. Following spinal injection the woman is turned to an identical right lateral position. This is maintained until just before incision to minimise aorto-caval compression, when she is placed in the wedged supine position. Sixty women undergoing elective caesarean section were randomised to receive spinal anaesthesia using hyperbaric bupivacaine in either the Oxford (group O), or the sitting position followed immediately by the wedged supine position (group S). Ephedrine 6 mg was given every minute that systolic blood pressure was less than 80% of baseline. In group S, 9/30 women lost pinprick sensation up to T4 at 5 minutes compared with 2/30 in group O (chi2 test, P = 0.04). Block height was more variable in group S than in group O (f test, P = 0.001). Blood pressure decreased by a greater amount initially: group S women required more ephedrine (15.5 +/- 12.9 versus 9.2 +/- 7.7 mg, t test, P = 0.03). Block height with spinal anaesthesia for caesarean section is more predictable and haemodynamically stable if the Oxford position is used whilst anaesthesia develops.

Clinical Trial↗

Comparison of pentastarch and Hartmann's solution for volume preloading in spinal anaesthesia for elective caesarean section.

We studied 160 patients undergoing elective Caesarean section under spinal anaesthesia who received a preloading volume of 15 ml kg-1 of 10% pentastarch in 0.9% saline, or Hartmann's solution, in a prospective, randomized, double-blind study. We compared the incidence of spinal-induced hypotension in each group. Hypotension was defined as a decrease in systolic arterial pressure to less than 70% of baseline values or < or = 90 mm Hg, whichever was the greater. The groups were comparable in physical characteristics and there was no serious morbidity. Fetal outcome was similar in both groups. Significantly more patients in the Hartmann's group (n = 38, 47.5%) developed hypotension than in the pentastarch group (n = 10, 12.5%) (P < 0.0001). Linear regression analysis showed that the only significant variable was type of fluid used. Blood glucose concentrations were not related to the presence of hypotension. We conclude that starches may be suitable for preloading in Caesarean section under spinal anaesthesia and provide an alternative to the aggressive use of vasoconstrictors.

Adolescent↗