Summary

Background and objective: Succinylcholine administration, laryngoscopy and tracheal intubation are followed by increased intraocular pressure. Various premedications have been advocated for preventing increases in intraocular pressure, especially in patients undergoing surgical repair of open globe due to penetrating eye trauma. Results of studies in this area have been controversial. Methods: In this double-blind study, three groups of 70 patients receiving sufentanil, lidocaine and placebo 90 s prior to intubation were evaluated and compared for intraocular pressure changes following succinylcholine administration, laryngoscopy and tracheal intubation. Results: Mean intraocular pressure measured 2 and 3 min after succinylcholine administration in groups receiving sufentanil and lidocaine was significantly lower than in the placebo group. Mean intraocular pressure changes in the three groups were −1.84, −2.03 and +2.82 mmHg, respectively in minute 2; −4.78, −4.73 and +1.35 mmHg, respectively in minute 5. There was a significant intraocular pressure decrease in the sufentanil and lidocaine groups, compared to the placebo group. The eye surgeons' satisfaction was also significantly higher with the sufentanil and lidocaine groups. Conclusion: Previous studies have yielded controversial results as to the effect of sufentanil and lidocaine in preventing intraocular pressure following succinylcholine administration, laryngoscopy and tracheal intubation. The present study affirms the preventive effect of these drugs on intraocular pressure increase.

Summary

Background and objective: We have investigated the concentrations of epinephrine, norepinephrine, vasopressin and angiotensin converting enzyme activity to explore the role of these mediators in the neuroendocrine response to laryngoscopy and tracheal intubation. Methods: One hundred (50 male, 50 female) ASA I patients aged 20–50 yr (mean ± SEM; 35.59 ± 0.99) were included in the study. They were undergoing elective surgery under standard anaesthesia induction and maintenance using tracheal intubation. Plasma concentrations of epinephrine, norepinephrine and vasopressin as well as plasma angiotensin converting enzyme activity were determined at four time points, before (T1) and after (T2) induction, and 2 (T3) and 5 min (T4) after intubation. Blood pressure and heart rate were recorded at corresponding times to reveal if any correlation existed between haemodynamic parameters and neuroendocrine response. Results: Heart rate increased after induction and intubation (P < 0.05) and decreased significantly at T4 (P < 0.05). Systolic blood pressure decreased significantly (P < 0.05) after induction and increased slightly after intubation decreasing to below baseline value (P < 0.05) at T4. Diastolic blood pressure increased slightly after intubation and decreased significantly (P < 0.05) at T4. Plasma epinephrine and norepinephrine concentrations decreased after induction and increased at T3 and T4 without reaching significance. Vasopressin concentrations increased slightly at T2 and T3 and decreased significantly at T4 (P < 0.05). Angiotensin converting enzyme activity was unaffected when compared with baseline values. Conclusions: Blood pressure, heart rate, plasma epinephrine, norepinephrine and vasopressin concentrations increased slightly in response to laryngoscopy and intubation, all returning to or below baseline 5 min later with no change in angiotensin converting enzyme activity in normotensive patients.

Summary

Background and objective: Reducing postoperative mechanical ventilation in patients undergoing liver transplantation may have clinical and organizational advantages. On the basis of our experience, we here evaluate the possibility of practising immediate tracheal extubation in the operating theatre. Methods: In this prospective study, patients consecutively undergoing liver transplantation between 1 June 1999 and 31 May 2004 were extubated in the operating theatre at the end of surgery on the basis of standardized and universally accepted criteria, under conditions of haemodynamic and metabolic stability. Results: Two hundred and seven of the 354 patients (58.5%) were extubated immediately after the completion of the surgical procedure (mean time between end of surgery and extubation: 0.4 ± 1.4 min); two were re-intubated. In the last of the 5 yr of the study, the percentage of immediate extubations increased to 82.5%. During the study period, there was a progressive increase in the number of immediate extubations per individual member of the team of anaesthetists. The pre-transplant Child-Pugh severity of the underlying liver disease did not predict rapid extubation, but the Model for End-stage Liver Disease score of <11 did (receiver operator characteristic area under the curve = 0.61; P < 0.05). Conclusions: Immediate extubation after liver transplantation is possible in a substantial percentage of cases; confidence, habit and a spirit of emulation are decisive factors in encouraging anaesthetists to extend this practice to the largest possible number of patients. A successful immediate extubation may be an important indicator of perioperative quality of care in liver transplantation.

Summary

Background and objective: To evaluate orotracheal intubation conditions after 1 min.

Patients and methods: A prospective randomized study with 376 adult American Society of Anesthesiologists (ASA) Grade I–III patients. Each patient received propofol, fentanyl and either suxamethonium (1 mg kg−1) or rocuronium. The intubating dose of rocuronium (2 × ED95) was preceded 4 min earlier by saline, or a 0.1 × ED95 priming dose of rocuronium, atracurium, cis-atracurium, vecuronium or mivacurium. Intubating conditions were graded as excellent, good or poor with respect to laryngoscopy, vocal cord position and movement and reaction to intubation and/or cuff inflation.

Results: There were significant differences (P < 0.05) in laryngoscopy between suxamethonium and rocuronium primed with saline, atracurium or cis-atracurium. With respect to vocal cord position and movement during intubation, rocuronium without priming differed significantly from all other groups and for reaction to insertion of tracheal tube and/or cuff inflation. Rocuronium without priming differed significantly from all other groups except for rocuronium primed with itself. The mivacurium group showed more signs of pre-curarization than other groups (P < 0.05). There were significant differences between rocuronium alone and the other groups when final intubating conditions were compared.

Conclusions: Priming rocuronium with 0.1 × ED95 of vecuronium, rocuronium, atracurium or cis-atracurium is a safe technique and did not increase risk of pre-curarization in healthy patients.

Summary

Background and objective: Minimizing cervical vertebrae motion during endotracheal intubation is important in patients with cervical instability. The aim of this study was to compare upper cervical spine extension during endotracheal intubation using three different techniques.

Methods: Duration of intubation and movement of upper cervical vertebrae during endotracheal intubation were compared in 33 patients undergoing lumbar laminectomy. Patients requiring tracheal intubation under general anaesthesia and neuromuscular blockade were randomly allocated into three groups – direct laryngoscopy, intubating laryngeal mask (LM) airway and fibreoptic laryngoscopy. The procedure was recorded by video-fluoroscopy and analysed with computer-assisted measurements. The maximum movement of the C1/C2 and C2/C3 vertebrae during intubation were obtained. Data were analysed using one-way analysis of variance with Bonferroni and Kruskal–Wallis tests.

Results: We found statistically significant movement between the first and second, but not between the second and third cervical vertebrae. The mean (±SD) movement at C1/C2 was 10.2 ± 7.3° with direct laryngoscopy, 5.0 ± 6.3° with LM and 1.6 ± 3.2° with fibreoptic laryngoscopy. This difference was statistically significant (P = 0.01) between the direct and fibreoptic laryngoscopy groups. The maximum movement at C2/C3 was 2.2 ± 10.1° with direct laryngoscopy, 3.5 ± 5.1° with LM and 0.5 ± 3.2° with fibreoptic laryngoscopy. Duration of intubation was significantly longer in the intubating LM group (P < 0.001).

Conclusion: We conclude that fibreoptic laryngoscopy is the more suitable intubation technique when cervical spine movement is not desired.

Summary

Background and objective: Changes in the middle latency auditory evoked response following the administration of opioids have been shown. However, it remains unclear as to whether these changes are due to a direct depressant effect of opioids on the middle latency auditory evoked response itself, or an indirect effect on account of their action in attenuating central nervous system arousal associated with noxious stimuli. By comparing changes in the middle latency auditory evoked response in intubated and non-intubated patients, receiving saline or remifentanil in different doses, this study attempts to answer this question.

Methods: Fifty-four patients were anaesthetized with isoflurane and nitrous oxide (0.9 MAC) and randomized to 1–6 groups. Groups 1–3 received a bolus injection of either saline 0.9%, low-dose remifentanil (1 μg kg−1) or high-dose remifentanil (3 μg kg−1) prior to intubation of the trachea. Groups 4–6 were not intubated following the bolus injection.

Results: Pa and Nb amplitudes of the middle latency auditory evoked response increased by 82% and 79% with intubation in the saline group (P < 0.005) and these changes were not seen in the patients given remifentanil. There was a significant linear trend for the reduction in Pa and Nb amplitude with increasing remifentanil dose (P < 0.05). In the absence of endotracheal intubation remifentanil had no effect on either the amplitudes or latencies of the waves Pa and Nb and there was no effect of dose. For the haemodynamic measurements remifentanil attenuated the pressor response to intubation (P < 0.001) and had a significant dose-related effect (P < 0.001) in the absence of intubation.

Conclusions: We demonstrated an effect of remifentanil on both the middle latency auditory evoked response and haemodynamic changes to endotracheal intubation. For the non-intubated patients there was only an effect of remifentanil on the haemodynamic measurements. This suggests that remifentanil has an effect on the middle latency auditory evoked response in attenuating the arousal associated with intubation of the trachea but has no effect in the absence of a stimulus.

Summary

Background and objective: This randomized, double-blinded, prospective study compared the effects of clonidine, esmolol or alfentanil on the level of hypnosis and haemodynamic responses to intravenous induction of anaesthesia and endotracheal intubation.

Methods: Forty-five patients scheduled for elective surgery were allotted to one of three groups. They were given either alfentanil 3 μg kg−1min−1 (n = 15); esmolol 1 mg kg−1min−1 (n = 16) or clonidine 3 μg kg−1 (n = 14) as a 10 min infusion. The infusions of alfentanil and esmolol, but not of clonidine, were maintained during endotracheal intubation. Anaesthesia was induced with midazolam (2 mg) and thiopental as required to suppress the eyelash reflex. Atracurium (0.5 mg kg−1) was given to produce neuromuscular block. Mean arterial pressure, heart rate, and bispectral index were recorded on arrival (baseline), after study drug infusion, after injecting midazolam and thiopental, as well as after endotracheal intubation. ANOVA and χ2-test were used for analysis.

Results: Blood pressure, heart rate and the bispectral index were unaltered by the study drugs, but thiopental requirements were reduced by alfentanil and clonidine (P < 0.014). Mean arterial pressure values (mean ± standard error of mean) in the alfentanil, esmolol and clonidine groups were: baseline: 107.8 ± 3.8; 106.6 ± 3.9; 103.4 ± 3.7 mmHg; after thiopental: 74.0 ± 4.2; 85.6 ± 4.3; 94.2 ± 4.1 mmHg and after endotracheal intubation: 91.7 ± 5.3; 114.1 ± 6.9; 123.6 ± 5.6 mmHg, respectively (two-way ANOVA, P < 0.001). Mean arterial pressure changed significantly after intubation from baseline (P < 0.001) after alfentanil (− 15%) and clonidine (+ 20%) but not after esmolol (+ 7%), while the changes between pre- and postintubation values were similar in all groups (24–33% increase). The bispectral index indicated that all patients had an adequate level of hypnosis, but the variability was higher in the esmolol group (P < 0.002).

Conclusions: None of the study drugs blocked the increase in mean arterial pressure induced by endotracheal intubation, but esmolol provided better overall haemodynamic stability. All groups had an adequate level of hypnosis.

Upper aerodigestive tract injury after endotracheal intubation is a rare but serious complication. The case of a 57-year-old female, who developed extensive neck and pneumomediastinum following a knee arthroscopy under general anaesthesia, is presented. Possible mechanisms of injury and management options are discussed.

Summary

Background and objective: Intubation of the trachea has been a risky cross-contamination procedure over the past decade because no perfect decontamination procedures exist. Infectious agents found on laryngoscopic devices have the potential for devastating spread of the human immunodeficiency virus, hepatitis viruses B and C and transmissible non-conventional agents. The purpose of this prospective observational study was to assess the quality of endotracheal intubation with disposable laryngoscope blades, under normal intubating conditions.

Methods: Anaesthetists were asked to complete daily questionnaires regarding the difficulty of intubation experienced using the Vital View® disposable laryngoscope blade (Vital Signs Inc, Totowa, NC, USA). The choice of the type of blade (conventional or disposable blade) for the first attempt at intubation depended only on the operating room assignment. Glottic visualization during laryngoscopy was assessed by the modified Cormack and Lehane classification. Difficult tracheal intubation was evaluated by the intubation difficulty scale (>5, procedure involving moderate to major difficulty).

Results: The anaesthetic staff recorded 219 intubations. One hundred-and-nineteen of first attempts at laryngoscopy were with disposable blades (DB group) and another 100 with conventional blades (CB group). There were no significant differences between the two groups for Cormack and Lehane score 3, for intubation difficulty scale scores >5 and for intubation difficulty scale score 0. There were 12 blade changes before successful intubation.

Conclusions: In routine use, the Vital View® disposable laryngoscope blade appears to be an efficient device because it does not modify the ease of endotracheal intubation in most cases. Nonetheless, it may be advisable to maintain conventional laryngoscopes in reserve for difficult intubations.

Summary

Background and objective: In a retrospective study, we examined the suitability of a departmental clinical protocol for anaesthesia induction with target-controlled infusion of propofol developed for fibreoptic intubation in spontaneously breathing patients scheduled for outpatient oral surgery at the dental clinic of the Vienna University Hospital.

Methods: Propofol was administered using target-controlled infusion (Diprifusor®) at increasing target plasma concentrations starting at 2.5 μg mL−1. After 10 min, an intravenous dose of alfentanil (5–10 μg kg−1) was given for pain reduction. After a further 2 min, the patient was evaluated for response to auditory stimulation. If unresponsive, fibreoptic intubation was performed, otherwise the target concentration was increased by 0.2 μg mL−1 every 2 min until non-responsiveness was attained.

Results: Tracheal intubation was successful in all patients without any haemodynamic instability. However, one patient required facemask ventilation for 2 min. No patient was aware of intubation. The plasma concentration required for non-responsiveness was 2.8 ± 0.4 μg mL−1 (mean ± SD).

Conclusions: When using a target-controlled infusion of propofol, fibreoptic intubation can be performed with complete amnesia of the procedure for the patient. However, assisted ventilation of the lungs may be necessary as spontaneous ventilation may cease.

Summary

Background and objective: When the endotracheal tube cuff is repeatedly aspirated to avoid excessive cuff pressure during nitrous oxide anaesthesia, a stable cuff pressure is eventually achieved. We assessed the time required to achieve a stable cuff pressure after repeated cuff deflation.

Methods: During 67% nitrous oxide and oxygen anaesthesia, air-filled cuffs of a standard tracheal tube (Mallinckrodt Hi-Contour®) were repeatedly deflated every 30 min for the first 3 or 4 h to inhibit excessive pressure (Groups Def-3 or Def-4, respectively, n = 10 for each); the cuff pressure was monitored for an additional 3 h. In some patients, the study was terminated at 1, 2, 3 and 4 h (n = 6 for each).

Results: Cuff pressure in Group Def-3, but not in Group Def-4, >22 mmHg after stopping cuff aspiration. Intracuff nitrous oxide concentrations increased during repeated cuff deflation and increased further in Group Def-3 during an additional 3 h (from 39.8 ± 4.7% to 44.3 ± 3.8%; P < 0.05), whereas intracuff nitrous oxide concentrations at 4 h were not different from those in Group Def-4 at the end of the study (43.7 ± 4.5% versus 42.3 ± 4.8%; P = 0.579).

Conclusions: When the air-filled cuff of the standard endotracheal tube is repeatedly deflated every 30 min for 4 h, but not for only 3 h, during nitrous oxide anaesthesia, a stable cuff pressure can be achieved without further deflation of the cuff. Our data also suggest that achieving an equilibrating nitrous oxide concentration in the cuff provides a subsequent stable cuff pressure.

Summary

Background and objective: Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value.

Methods: A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification.

Results: Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5 cm or a sternomental distance <12.5 cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%.

Conclusions: The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.

We present a case of microlaryngoscopy in a patient with an unexpectedly difficult airway. The airway was managed by using an oesophageal-tracheal Combitube (Kendall-Sheridan, Argyle, NY) (ETC)and a fibre-optic bronchoscope (Pentax-Japan-5mm).

Although subglottic cysts have previously been reported as a cause of airway obstruction in the neonate, they have previously been considered to be a relatively rare cause. Cystic narrowing of the subglottis has been associated with endotracheal intuhation. With improving survival of pre-term infants the incidence of the condition could be expected to rise. Prior to 1996, only 58 cases had been reported in the literature. We believe that the true incidence of the condition has been considerably under-reported. Over a six-month period our unit diagnosed five cases of compressible cysts in the subglottis in low birth weight, pre-term infants. All patients underwent diagnostic microlaryngobronchoscopy and vaporization of the cysts by CO2 laser. Three children required more than one procedure. In all cases a satisfactory airway was achieved. The pathogenesis, diagnosis and treatment of the condition is discussed.

This short communication describes the use of the Carden anaesthetic tube during surgery in and around a tracheostome. The technique, which greatly facilitates access to the operating field, is described along with it's indications and contraindications.

We would like to recommend extending the use of the Carden tube to operations around a tracheostome, thereby maximizing surgical access.