F. S. Xue

Lightwand guided intubation in paediatric patients with a known difficult airway : a report of four cases

The anaesthetic management of children with craniofacial abnormalities often presents unique challenges because soft tissue and bony abnormities can affect the airway and influence airway management. We report four paediatric patients with predicted difficult airways due to craniofacial abnormalities. They all had a laryngeal view of Cormack–Lehane grade IV and were impossible to intubate using direct laryngoscopy. Fibreoptic intubation was also repeatedly attempted but was not successful. All the tracheal intubations were completed using a lightwand on the first attempt in less than 30 s. We consider that lightwand guided intubation technique may be a useful alternative approach to fibreoptic intubation technique in managing the difficult paediatric airway.

The effects of head flexion on airway seal, quality of ventilation and orogastric tube placement using the ProSeal™ laryngeal mask airway*

This prospective self‐controlled study was designed to evaluate the influences of head flexion on airway seal, quality of ventilation, and orogastric tube placement through the ProSeal™ laryngeal mask airway (ProSeal LMA™) in 80 anaesthetised, paralysed adult patients.

Combined morphine and limb remote ischaemia postconditioning may produce an enhanced cardioprotection.

The limb remote ischaemia postconditioning (RIPOC), a newly conceived idea of applying brief limb ischaemic stimulus after onset of the myocardial ischaemia but prior to the reperfusion, can offer the possibility of applying this cardioprotective strategy to the patients with acute myocardial infraction. Although increasing numbers of circles and duration of limb ischaemia may augment the protective effect of the limb RIPOC, these ways are not feasible in a clinical setting. Morphine, a classic opioid drug, has been proven to enhance the cardioprotection obtained by the other interventions. Because both the RPIOC and opioid drugs produce the cardioprotection by multiple pathways, and there may be overlaps and cross talk in their mechanisms, we hypothesize that a combination of morphine and the limb RIPOC may produce an enhanced cardioprotection.

Different small-dose sufentanil blunting cardiovascular responses to laryngoscopy and intubation in children: a randomized, double-blind comparison

BACKGROUND Sufentanil is a potent opioid analgesic frequently used in clinical anaesthesia. This prospective, randomized, double-blind study was designed to assess the efficacy of different small-dose sufentanil attenuating the cardiovascular intubation response in healthy children, aiming at determining the optimal dose of sufentanil for this purpose. METHODS A total of 165 children aged 3-9 yr were randomized to one of four groups to receive the following in a double-blind manner: normal saline (Group 1), sufentanil 0.1 microg kg(-1) (Group 2), sufentanil 0.2 microg kg(-1) (Group 3), and sufentanil 0.3 microg kg(-1) (Group 4). Anaesthesia was induced with propofol 2.5 mg kg(-1) and vecuronium 0.1 mg kg(-1). Non-invasive blood pressure (BP) and heart rate (HR) were recorded before induction of anaesthesia (baseline value), at immediately before intubation (post-induction values), at intubation, and at 1 min intervals for 5 min after intubation. The per cent changes of systolic blood pressure (SBP) and HR during the observation were calculated. RESULTS Except for Group 4, tracheal intubation caused significant increases in BP and HR in Groups 1, 2, and 3 compared with baseline values. BP and HR at intubation and their maximum values during the observation were significantly different among the four groups. The maximum per cent increases of SBP and HR during the observation were 20 and 28% of baseline values, respectively, in Group 2, 13 and 13% in Group 3, and 0 and 4% in Group 4 compared with 24 and 37% in Group 1. Except for the Group 3 vs Group 4 comparison, the incidences of SBP and HR per cent increases >30% of baseline values were also significantly different among the four groups. CONCLUSIONS In combination with propofol for induction of anaesthesia in children, the bolus administration of sufentanil can produce a dose-related attenuation of the cardiovascular intubation response and sufentanil 0.3 microg kg(-1) can completely abolish the cardiovascular intubation response.

Is it unnecessary to confirm successful facemask ventilation before administration of a neuromuscular blocking agent

We would like to raise some points relating to Warters et al.’s thoughtprovoking article [1]. Their incidence of difficult facemask ventilation is significantly higher than reported previously in large cohorts of patients undergoing anaesthesia [2, 3]. We are concerned that the drug doses used for induction may have resulted in an inadequate depth of anaesthesia, leading to more frequent airway obstruction and laryngospasm, both common causes of difficult facemask ventilation [4]. Moreover, we do not feel that the authors clearly described if they had used an optimal technique when assessing facemask ventilation. This study showed that after induction of anaesthesia, administration of rocuronium did not worsen facemask ventilation in any patient, but improved it in 67% of cases. These results are supported by a recent study [2]. However, we still believe that the available evidence is not strong enough to answer the question of whether or not one should routinely ensure successful facemask ventilation before administering a neuromuscular blocking drug (NBD), as these studies have excluded patients with known or predicted difficult airways. In patients with normal airways, the usual causes of difficult facemask ventilation are airway or glottic closure due to irritation and opioidmediated muscle rigidity [4]; these improve with neuromuscular blockade. In contrast, in patients with difficult airways, common causes of difficult facemask ventilation are overcrowding and dysfunction of upper airway structures due to limited mandibular space and reduced displaceability of the soft tissues. In this case, loss of muscle tone by neuromuscular blockade may cause further upper airway soft tissue collapse, resulting in complete upper airway obstruction that cannot be relieved by routine airway manoeuvres [5]. We believe that successful facemask ventilation should be confirmed before administering a NBD, especially in patients with a known or predicted difficult airway. If a patient’s lungs are difficult to ventilate by facemask following induction of anaesthesia, our routine practice is an immediate attempt at direct laryngoscopy. If the view is good, and the chances of achieving successful tracheal intubation are high, we give a NBD. However, if the view at laryngoscopy is poor and tracheal intubation fails, we immediately follow the rescue airway algorithm for a ‘cannot intubate – cannot ventilate’ scenario, including laryngeal mask airway insertion.

The circulatory responses to tracheal intubation in children: a comparison of the oral and nasal routes

The circulatory responses to laryngoscopic tracheal intubation in 62 healthy children undergoing surgery requiring tracheal intubation were studied. They were randomly assigned to receive either the oral or nasal route for intubation. Baseline non‐invasive blood pressure and heart rate were recorded following induction of anaesthesia, at intubation and then every minute for 5 min. The percentage changes of systolic blood pressure and heart rate during the measurement period were calculated. The results demonstrated that intubation time was significantly longer in the nasal group. Both oral and nasal intubation caused significant increases in blood pressure and heart rate compared to baseline and postinduction values. However, there were no significant differences found between the two groups in relation to blood pressure and heart rate. The two groups were similar with respect to the percentage changes of systolic blood pressure and heart rate during the observation period. It is concluded that oral and nasal intubation using a direct laryngoscopy can result in a similar circulatory response in anaesthetised children.

Influence of acute normovolaemic haemodilution on the dose-response and time-course of action of atracurium.

Background: Acute normovolaemic haemodilution is a common method to save and avoid homologous blood transfusion during surgery. The aim of this study was to evaluate the influence of acute isovolaemic haemodilution on the dose‐response and time‐course of action of atracurium.

Difficult tracheal tube passage and subglottic airway injury during intubation with the GlideScope(®) videolaryngoscope: a randomised, controlled comparison of three tracheal tubes.

Difficulty during placement of the tracheal tube is a known problem when intubating with the GlideScope®, which may lead to subglottic airway injury. This randomised, controlled clinical trial was designed to compare the resistance to passage of PVC (polyvinyl chloride), reinforced or BlockBuster tracheal tubes during intubation with the GlideScope. Secondary outcomes included the time taken to intubate and assessment of subglottic airway injury. One‐hundred and seventy‐seven patients were included in the data analysis. There was difficult tracheal tube passage (moderate or severe resistance) in 15 (21.4%) patients using the PVC tube compared with 4 (7.4%) and 1 (1.9%) using the reinforced and BlockBuster tubes, respectively (p = 0.003 for PVC vs. BlockBuster). The median (IQR [range]) time taken to intubate was 35 (27–45 [15–115]) s, 25 (20–27 [15–110]) s and 25 (22–30 [16–90]) s, respectively, (p < 0.001 for PVC vs. reinforced as well as PVC vs. BlockBuster). Subglottic airway injury, assessed using a fibreoptic bronchoscope after extubation, was higher with the PVC tube (p < 0.001) and the reinforced tube (p = 0.012) compared with the BlockBuster tube. We conclude that the BlockBuster tracheal tube is a better choice for orotracheal intubation with the GlideScope than PVC or reinforced tubes.

Cholinergic agonists may produce preservation of myocardial ischaemia/reperfusion injury

The best treatment for myocardial infarction is to restore blood flow in the ischaemic region, though it will bring new myocardial damage known as myocardial ischaemia/reperfusion (I/R) injury. Both the ischaemia preconditioning and the ischaemia postcondioning have been shown to reduce the myocardial I/R injury, but their deficits restrict wide clinical availability. It has been demonstrated that inflammation plays a critical role in the I/R injury process. Also plasma levels of cytokines and inflammation response can be regulated by specifically augmenting cholinergic signaling via the efferent vagus nerve and alpha7 subunit-containing nicotinic acetylcholine receptor (alpha7nAChR). Because cholinergic modalities, acting through vagus nerve- and/or alpha7nAChR-mediated mechanism, have been confirmed to suppress excessive inflammation during the I/R injury in kidney, liver, lung and intestine, therefore, we hypothesize that cholinergic agonists may also provide a protection for the myocardial I/R injury.

The modified ventilating tube changer to facilitate tracheal intubation using the GlideScope® in patients with a limited mouth opening

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