Facilitation of laryngeal mask airway insertion: effects of remifentanil administered before induction with target-controlled propofol infusion.

Eighty-six adult day-case patients were recruited into a prospective, randomised study and allocated to one of two groups. Patients received either intravenous remifentanil 0.3 microg.kg(-1) or an equivalent volume of sodium chloride 0.9% followed by induction of anaesthesia with propofol target-controlled infusion until the effect (brain) site calculated concentration was 2 microg.ml(-1). Jaw opening and ease of laryngeal mask insertion were assessed immediately after mask insertion. A higher incidence of failure of induction of anaesthesia was observed in the control group compared with the remifentanil group [15 (35%) vs. 3 (7%); p < 0.01] and addition of remifentanil significantly increased the ease and success of laryngeal mask insertion, with grade 1 (no coughing/gagging) conditions observed in 29 (68%) of the remifentanil group and 21 (49%) of the control group (p < 0.01). The doses of remifentanil and propofol used were not associated with any significant cardiorespiratory instability. In conclusion, when combined with propofol target-controlled infusion, remifentanil 0.3 microg.kg(-1) facilitates laryngeal mask insertion with minimal adverse haemodynamic changes.

Post partum magnetic resonance imaging: lumbar tissue changes are unrelated to epidural analgesia or mode of delivery.

Thirty five women consented post partum to daily lumbar back pain assessments and magnetic resonance imaging (MRI) (0.15 Tesla) within 48 hours of delivery using a T(1) weighted spin echo and a fat suppression sequence (STIR) to identify tissue water. Nine women (26%) had lumbar disc abnormalities on MRI scan. Variable degrees of soft tissue changes in the lumbar region were observed using the STIR sequence in all patients after delivery. Eight women (23%) had mild, 15 (43%) moderate, and 12 (34%) severe changes with an average of 5 segments involved. These changes were reversible and related neither to the mode of delivery, nor to the trauma of epidural cannulation.

Flow characteristics of long spinal needles.

A 120 mm, 27-gauge needle has recently been introduced for subarachnoid anaesthesia when using a single-space, combined spinal-extradural technique. The flow characteristics of this needle were compared with those of a 120 mm, 26-gauge needle using a pressure monitor infusion pump. Surprisingly, the resistance to fluid flow of the 26-gauge needle was twice that of the 27-gauge needle. The results of this experiment were confirmed by the findings of a clinical study undertaken in 100 obstetric patients who required regional anaesthesia. The time taken from dural puncture to appearance of cerebrospinal fluid at the hub of the needle was on average three times greater with the 26-gauge needle.

Acute tissue damage following epidural cannulation: a comparison between the midline and paramedian approach in obstetric patients.

Forty obstetric patients were randomly allocated to receive either a midline or paramedian approach to the epidural space using loss of resistance to air. Tissue trauma was assessed by blinded observers, clinically by the presence of pain and radiologically using magnetic resonance imaging (MRI). Technical difficulties with imaging reduced those who were scanned to 10 in the paramedian group and 8 in the midline group. Lateralizing signs of tissue oedema were not related to the method of epidural cannulation. There was no significant difference in localized back pain between the two groups, and this was not related to MRI findings. Pain did not persist for more than 4 days.

Posture and the spread of hyperbaric bupivacaine in parturients using the combined spinal epidural technique.

This study was undertaken to analyze the effect of posture on the spread of hyperbaric bupivacaine in pregnant women using a combined spinal extradural technique, and to assess the quality of analgesia provided by 10 mg bupivacaine when using this technique. Fifty parturients undergoing elective Caesarean section under regional anaesthesia were randomly allocated to receive 2.0 ml hyperbaric bupivacaine 0.5% in either the sitting or left lateral position. Spinal injection was performed with a 27 gauge, 120 mm long spinal needle using a single space combined spinal extradural technique. The onset time to analgesia at T4, and grade 3 motor block was on average 7.7 min and 6.9 min respectively in the lateral group, compared with 10.8 min (P < 0.05) and 9.4 min (P < 0.05) in the sitting group. Nine women in the sitting group and one woman (P < 0.05) in the lateral group required epidural supplementation. Hypotension occurred in 48% of the parturients in the lateral group and in 13% (P < 0.05) of the parturients in the sitting group. Nausea was noted in 61% of the parturients in the lateral group and in 22% (P < 0.05) of the parturients in the sitting group. There was no difference between the two groups in neonatal outcome. Overall, the position of the patient during induction of spinal anaesthesia does influence the rate of onset of analgesia and motor blockade. Injection of 10 mg hyperbaric bupivacaine in the sitting position would not provide adequate analgesia for Caesarean section when using a single space combined spinal extradural technique.

Incremental spinal anaesthesia for elective caesarean section: maternal and fetal haemodynamic effects.

We have performed serial haemodynamic investigations in 20 women undergoing elective Caesarean section under continuous spinal anaesthesia with a 32-gauge catheter with 0.5% heavy bupivacaine. Cardiac output was measured by Doppler and cross-sectional echocardiography at the aortic valve. Doppler flow velocity waveforms were recorded also from the umbilical artery. A block to T4 or above was achieved in all patients. The median dose of 0.5% bupivacaine administered was 2.0 ml (range 1.5-4.5 ml). Mean cardiac output increased from 7 to 8 litre min-1 after preloading with Ringer lactate solution 1.5 litre and then remained unchanged after injection of bupivacaine. Two subjects developed hypotension, although mean values of arterial pressure and umbilical artery pulsatility index did not change. The median umbilical artery pH was 7.27 (range 6.98-7.32) and there was a significant correlation between pH and the maximum percentage decrease in cardiac output. The results suggest that continuous spinal anaesthesia is associated with greater haemodynamic stability than single bolus spinal injection.

General anaesthesia and the hypereosinophilic syndrome: severe postoperative complications in two patients.

Two patients with markedly increased eosinophil counts developed severe postoperative complications after general anaesthesia. One patient suffered life-threatening Adult Respiratory Distress Syndrome (ARDS), while the other presented with a coagulopathy and less severe respiratory problems. The hypereosinophilic syndrome is described and the possibility of a role of eosinophils in the pathogenesis of tissue injury is discussed. These cases suggest that, in patients with marked eosinophilia requiring general anaesthesia, perioperative steroid cover is advisable. This may reduce or prevent serious lung damage and other complications.

Difficult tracheal intubation: a retrospective study.

This is a retrospective study of patients whose tracheas were impossible to intubate on a previous occasion. There is a correlation between the degree of difficulty and the anatomy of the oropharynx in the same patient. The study was initially on obstetric patients but was extended to nonobstetric surgical patients in order to increase the number of cases investigated. The incidence of failed intubations in the obstetric group over a 3-year period was seven out of 1980 cases, whereas in the surgical group the results were six out of 13,380 patients. Any screening test which adds to our ability to predict difficulty in intubation must be welcomed, as failure to intubate can potentially lead to fatality.