Comparison between tracheal tubes for orotracheal fibreoptic intubation.

We have compared impingement of the tracheal tube against the larynx using a standard preformed tube, warmed preformed tube or two flexible spiral-wound tracheal tubes with different tip designs, in 100 adult patients undergoing orotracheal fibreoptic intubation under general anaesthesia, in a prospective, randomized study. The rates of impingement were 20 of 30 with the standard tube, 12 of 30 with the warmed standard tube (P = 0.07) and eight of 20 with both spiral tubes. However, impingement with the spiral tubes took longer to overcome if a sharp tipped rather than an obtuse tipped tube was used. Manipulations after impaction led to oesophageal intubation in one patient, and in one patient fibreoptic intubation failed. We conclude that resistance to the tracheal tube occurred frequently when the spiral-wound tubes were used.

Laryngoscopy and fibreoptic intubation in acromegalic patients.

Acromegaly is recognized as a cause of difficulty in airway management and tracheal intubation. We evaluated prospectively the conditions for laryngoscopy and fibreoptic intubation in 15 acromegalic patients. Each patient served as his or her own control. Ventilation of the lungs with a face mask was successful in all patients. In five of 15 patients the vocal cords could not be seen using the Macintosh laryngoscope with a size 5 blade. Difficult laryngoscopy was associated significantly with the number of attempts required to see the vocal cords with the fibrescope (P < 0.01, Spearman rank correlation). The larynx could not be seen with both techniques in one patient, and the trachea was intubated blindly with the help of an introducer. Our results showed that fibreoptic intubation may prove difficult or fail in acromegalic patients. Difficulties in seeing the vocal cords with a fibrescope were present most often in patients who also had probable intubation difficulties with a rigid laryngoscope.

Comparison between the Ovassapian intubating airway and the Berman intubating airway in fibreoptic intubation.

The most common indication for employing the fibreoptic technique for intubation is when a difficult intubation is anticipated. It may also be used when intubation unexpectedly proves difficult with a rigid laryngoscope in anaesthetized patients. However, failures with orotracheal fibreoptic intubation have been reported in up to 9.5% of cases, although only two possible equipment related causes of intubation difficulties have been identified. The Berman intubating airway and the Ovassapian intubation airway in fibreoptic orotracheal intubation have been compared in 65 patients. The study was randomized and for fibreoptic endoscopy each patient served as his or her own control. The results indicate that both airways can be used for orotracheal fibreoptic intubation in anaesthetized patients. The Berman airway offers easier visualization of the vocal cords than the Ovassapian airway, provided that the Berman airway is of an adequate size and positioned in the midline. Upon impingement of the intubation tube, completing the tracheal intubation is more difficult with the Berman airway than the Ovassapian airway.

Topical anaesthesia of the nasal mucosa for fibreoptic airway endoscopy.

We have compared four methods of topical anaesthesia of the nostril for fibreoptic airway endoscopy in a randomized study with 31 unpremedicated volunteers, each serving as his or her own control. Lignocaine spray, EMLA cream, three cotton swabs soaked in 4% lignocaine solution, or 2% lignocaine gel was applied in a nostril for 3 min. Application of lignocaine spray was rated as the most unpleasant and EMLA cream the least unpleasant. Spray and gel caused an increase in arterial pressure. Anaesthesia of the mucosa, tested by passing a bronchoscope through the nose to the oropharynx was best with lignocaine spray or gel. Gel or EMLA, but not the local anaesthetic applied with swabs, obscured vision. When slight obscurity of vision is not a problem, local anaesthetic gel is recommended for anaesthesia of the nasal mucosa. Premedication or sedation is recommended for all the methods described here.

Effects of alfentanil on the responses to awake fiberoptic nasotracheal intubation.

Intubation conditions and pressor response were assessed in 30 healthy patients undergoing awake nasotracheal intubation. The patients were premedicated with peroral diazepam. All the patients were sedated with intravenous diazepam 0.1 mg/kg. Alfentanil 20 micrograms/kg or saline was administered in a double-blind fashion. Alfentanil caused moderate respiratory depression but significantly improved conditions for fiberoscopy. In the control group, arterial pressures and heart rate increased significantly immediately after tracheal intubation. These responses were attenuated by alfentanil.

Efficacy of 0.3 mg morphine intrathecally in preventing tourniquet pain during spinal anaesthesia with hyperbaric bupivacaine.

Tourniquet-induced pain is probably mediated by C-fibres. The ability of morphine to interrupt this nociceptive conduction was studied in a double-blind fashion by administering either morphine 0.3 mg or saline intrathecally along with hyperbaric bupivacaine 15 mg for spinal anaesthesia in 40 patients undergoing orthopaedic surgery on the lower extremity. The block characteristics were similar in both groups. During surgery, no patient in the morphine group complained of pain, whereas in the saline group one patient complained of pain caused by the tourniquet and two other patients experienced surgical pain. A 60-min experimental thigh tourniquet pressure provocation (53 kPa for 20 min; 0 kPa for 20 min; 53 kPa for 20 min) on the contralateral unoperated extremity was then performed following surgery, when the spread cephalad of the sensory block had decreased below the T10 dermatomal level. Eight patients in the morphine group experienced no pain in this test, compared with two patients in the saline group (P less than 0.05). The remaining 12 patients in the morphine group had pain responses similar to those patients not given morphine. Intrathecal morphine provides a level of prophylaxis against tourniquet pain. However, the dosage employed here was associated with urinary and emetic side-effects.

Arterial hypertension associated with the use of a tourniquet with either general or regional anaesthesia.

A hypertensive patient with left cardiac enlargement developed marked hypertension under general anaesthesia, during which time a tourniquet was applied around his thigh. When the tourniquet was released, severe hypotension ensued which responded to therapy. The patient, however, died 16 h later of a myocardial infarction. Because of this incident, the anaesthetic and haemodynamic data of 699 patients who underwent limb surgery with a pneumatic tourniquet inflated for at least an hour were retrospectively examined using multivariate analysis. A 30% increase in systolic and/or diastolic arterial blood pressure occurred in 27% of the total patient material and in 67% of those who had had a general anaesthetic. There was a higher frequency of the occurrence of "tourniquet hypertension" with older age, longer operations and the operation site being the lower rather than the upper limb. Tourniquet hypertension rarely occurred in patients with spinal anaesthesia (2.7%) and brachial plexus blockade (2.5%), while those with intravenous regional anesthesia had a higher incidence (19%) of hypertension.

Intravenous regional anaesthesia below the knee. A cross-over study with prilocaine in volunteers.

The quality of anaesthesia provided by three dosages of prilocaine, 40 ml 0.5%, 20 ml 1%, or 40 ml 1%, administered in random order, for intravenous regional anaesthesia of the lower extremity below the knee was compared in six volunteers. Limited sensory blockade was achieved in the groups with 40 ml 0.5% and 20 ml 1% during the 30-minute test period. One subject was not fully anaesthetised with any of the dosages used. Recovery was rapid (mean 12-13 minutes) in these two groups. In two subjects given 40 ml of 1%, complete recovery took 90 minutes. At 30 minutes, the degree of flexion remaining in the great toe (control 100%) was 4% in the groups who received 40 ml of 0.5% and 1%, but 34% in those who received 20 ml of 1% respectively. Full motor recovery was achieved in 8-9 minutes. Five of six volunteers who received the 400-mg dose experienced subjective signs of central nervous system side effects when the cuff was released. In this group, the mean plasma level of prilocaine at 2 minutes was 1.22 micrograms/ml, maximum 2.12 micrograms/ml. In a radiological examination, no leak of contrast medium under the tourniquet cuff (300 mmHg) was detected. The development of anaesthesia was fastest following the largest dose, but the large number of central side effects makes that dosage less suitable for clinical work.

Effects of three anaesthesia methods on haemodynamic responses connected with the use of thigh tourniquet in orthopaedic patients.

Haemodynamic changes were studied in 51 patients undergoing orthopaedic surgery of the lower extremity, including exsanguination and thigh tourniquet for longer than 60 min. The patients were randomly divided into three anaesthesia groups: general anaesthesia (including enflurane), epidural anaesthesia (20 ml 0.5% bupivacaine) and spinal anaesthesia (3 ml 0.5% bupivacaine). During the study, five epidural and one spinal patient excluded from haemodynamic comparison required general anaesthesia because of pain from the surgery or ischaemia. In the general anaesthesia group, there was a rise in either systolic or diastolic arterial pressure of over 30% of the control value in 8/15 patients. In the spinal anaesthesia patients, there was a transient rise above 30% in only one patient out of 15 and no rise in the 15 epidural group patients. On the other hand, 11/15 of the epidural patients needed additional analgesics and/or sedation for pain or restlessness. The mean rise in the haemodynamic parameters including CVP was small on inflation of the tourniquet cuff; on deflation there was a mean decrease in CVP of 1-3 cmH2 (0.1-0.3 kPa), the maximum decrease being 8 cmH2O (0.8 kPa). The mean decrease in systolic arterial blood pressure ranged from 2 to 14 mmHg (0.27 to 1.87 kPa) when the cuff was deflated.