Prevailing practices in airway management: a prospective single-centre observational study of endotracheal intubation

INTRODUCTION

Airway management during anaesthesia has potential difficulties and risks. We aimed to investigate the utility of routine airway assessment for predicting difficult tracheal intubation, review the prevailing practice of videolaryngoscope use amongst anaesthetists in a teaching hospital and determine the incidence of intraoperative and postoperative airway-related complications.

METHODS

A prospective observational study of 1,654 patients undergoing general anaesthesia with endotracheal intubation over a seven-month period was performed. Data regarding airway and anaesthetic management was collected and analysed.

RESULTS

Videolaryngoscopes were used as the first-choice equipment in 60.5% of the cohort. The incidence of difficult intubation was 2.1%, of which 45.7% of cases were unanticipated. The sensitivity of airway assessment was 54.3%, with a positive predictive value of 8.1%. When difficult intubation was anticipated, more videolaryngoscopes were used as the first equipment of choice compared to the Macintosh laryngoscope (p < 0.001). In the Macintosh group, more patients required a change of airway equipment (p = 0.015), but the number of intubation attempts was similar (p = 0.293). The incidence of intraoperative (p = 0.920) and postoperative complications (p = 0.380) were similar in both groups.

CONCLUSION

Using the current predictors of difficult intubation, half of the difficult airways we encountered were unanticipated. Videolaryngoscopes were preferred when difficulty was anticipated and were also used in routine tracheal intubation.

Comparison of results from novice and trained personnel using the Macintosh laryngoscope, Pentax AWS®, C-MAC™ and Bonfils intubation fibrescope: a manikin study

INTRODUCTION

Indirect laryngoscopes offer improved laryngeal view and higher success rates of intubation, particularly for difficult airways. We hypothesised that: (a) the time required for intubation, overall success rates and ease of intubation with indirect laryngoscopes would be better than with the Macintosh laryngoscope; and (b) novices may achieve higher success rates and intubate faster using indirect laryngoscopes.

METHODS

In a cross-sectional observational study, 13 novices and 13 skilled anaesthetists were recruited. Participants were compared when intubating a manikin simulating normal and difficult airway scenarios using the Macintosh laryngoscope, Pentax Airway Scope® (AWS), C-MAC[TM] and Bonfils intubation fibrescope.

RESULTS

There was no significant difference in intubation success rates between the groups. Skilled anaesthetists intubated faster than novices with Pentax AWS in the difficult airway scenario (22 s vs. 33 s, p = 0.047). The mean intubation times for C-MAC and Pentax AWS were shorter than for the Macintosh laryngoscope and Bonfils intubation fibrescope in both difficult (C-MAC: 24 s, Pentax AWS: 28 s, Macintosh: 80 s, Bonfils: 61 s; p < 0.001) and normal (C-MAC: 17 s, Pentax AWS: 19 s, Macintosh: 39 s, Bonfils: 38 s; p = 0.002) airway scenarios.

CONCLUSION

We found that intubation success was more than 85% with all indirect laryngoscopes compared to 69% for the Macintosh laryngoscope. Both C-MAC and Pentax AWS achieved faster intubation times compared to the Macintosh laryngoscope and Bonfils intubation fibroscope for both airway scenarios. Skilled anaesthetists were 33% faster than novices when intubating a difficult airway using Pentax AWS.

Perioperative risk factors in obese patients for bariatric surgery: a Singapore experience

INTRODUCTION

Morbid obesity and obstructive sleep apnoea (OSA) are increasingly encountered in anaesthetic practice today. Difficult intubation may be seen more frequently in our practice. This high-risk group may also be more prone to complications in the postoperative period.

METHODS

We reviewed a consecutive series of patients who had undergone laparoscopic gastric banding at our institution from 2001 to 2006. The incidence of difficult intubation, early postoperative complications and its attendant risk factors were studied.

RESULTS

Severe OSA and neck circumference greater than 44 cm were factors associated with difficult intubation in morbidly obese patients who presented for bariatric surgery. Asthma and increasing age may be associated risk factors for adverse events in the postoperative period.

CONCLUSION

It is important to anticipate and prepare for a difficult intubation scenario in patients with severe OSA and a larger neck circumference. Close monitoring is recommended for patients with respiratory comorbidities and advanced age.

A prospective audit of critical incidents in anaesthesia in a university teaching hospital

INTRODUCTION

We aimed to reduce mortality and morbidity in anaesthesia by identifying common factors contributing to critical incidences and 'near misses'.

MATERIALS AND METHODS

We carried out a prospective survey over a 2-year period from May 1999 to April 2001 of all reported critical incidents in patients undergoing anaesthesia. Critical incidents were reported anonymously, using the Anaesthetic Incident Monitoring Study form. This consisted of structured questions with tick box answers. Completed forms were reviewed and after open discussion with the department, preventive strategies and guidelines were developed and introduced.

RESULTS

A total of 116 critical incidences were reported in 108 patients. These are events that have resulted or could have resulted in an adverse outcome for the patient. Airway incidences were the commonest incidence reported (33.6%), followed by pharmacological problems like wrong drug or dose (28.4%). These occurred most often during maintenance and recovery from anaesthesia largely due to human factors like inattention, haste and failure to check equipment. They were preventable in 76% of cases. As a consequence, 33.6% of incidents resulted in cardiac arrest or major physiological change. There was no adverse outcome in 36.2%. From a review of the critical incident reporting, organisation of manpower was improved to ensure adequate supervision of junior staff. Checking of equipment and drug before use was constantly emphasized.

CONCLUSION

Critical incident reporting is a useful tool for quality assurance programmes. It analyses human and systems problems to ensure improved patient care.

Unanticipated admission after day surgery

Day surgery is becoming more common due to its cost effectiveness as well as patient acceptance. With increasing caseloads, there is a need to maintain quality of care. The purpose of this study is to identify the reasons for unanticipated admissions in our day surgical population, with the aim of improving efficiency of day surgical services, yet maintaining a high standard of patient care. A retrospective review of records of patients who were admitted over the two-year study period was conducted. Unanticipated admission was defined as unplanned admission after a day surgical procedure. Data relating to physical status, perioperative complications and reasons for hospital admission were recorded. A total of 10,801 procedures were done, and 163 patients were admitted. The unanticipated admission rate was 1.5%. Most of the admissions were surgically related (62.8%), followed by anaesthesia (12.2%), social (9.5%) and medical reasons (8.1%). Seventy-five percent of these admissions were potentially preventable. The majority were due to common problems like postoperative pain, admission for surgical observation and for social reasons. Non preventable causes (25%) were mainly due to unrelated medical problems.

Clinical update on managing the obstructed airway

The upper airway can obstruct due to soft tissues, blood, secretions and infections. In patients who are sedated, anaesthetised or unconscious, the commonest cause is due to loss of airway muscle tone. The usual site of obstruction is the soft palate followed by the epiglottis and occasionally the tongue. To relieve the obstruction, a head tilt, chin lift jaw thrust and open mouth manoeuvre should be performed. This will tense the muscles in the floor of the mouth causing the hyoid and larynx to be lifted away from the posterior pharyngeal wall. Oral and nasal airways are useful adjuncts to improve airway patency. In patients who are unconscious or adequately anaesthetised, the laryngeal mask or Combitube could be used especially in the difficult airway situation. As there is a significant decline in performance with time, it is important to maintain airway skills through regular practice and evaluation.

Postoperative sore throat after routine oral surgery: influence of the presence of a pharyngeal pack

A randomized clinical trial was conducted to investigate the effect of the presence of a pharyngeal pack during endotracheal anaesthesia on the incidence of postoperative sore throat. The patients were anaesthetized with fentanyl, thiopentone and atracurium. Thirty-six patients were anaesthetized without placement of pharyngeal packs while 26 patients had pharyngeal packs inserted. There were no significant differences in the incidence or severity of sore throat postoperatively in the two groups (P=0.23). These results contradict previous studies, which showed an increase in the incidence of postoperative sore throat after the use of pharyngeal packs.

Anaesthesia for caesarean section in a patient with Eisenmenger's syndrome

Eisenmenger's syndrome was originally described in 1897 and redefined by Wood in 1958. This syndrome includes pulmonary hypertension with reversed or bi-directional shunt associated with septal defects or a patent ductus arteriosus. A 27-year-old G2 PO with Eisenmenger's syndrome presented to the hospital for management at 17 weeks of pregnancy. She was advised termination of pregnancy but she refused. An elective caesarean section was performed successfully under general anaesthesia uneventfully at 29 weeks due to severe intrauterine growth retardation (IUGR). Patient's postoperative complications like pulmonary thromboembolism, the advantages and disadvantages of anticoagulation are discussed. Pregnancy carries substantial maternal and fetal risk for patients with pulmonary hypertension and Eisenmenger's syndrome. Although pregnancy should be discouraged in women with Eisenmenger's syndrome it can be successful.

Laryngeal mask insertion using thiopental and low dose atracurium: a comparison with propofol

PURPOSE

To compare the laryngeal mask airway (LMA) insertion conditions produced by propofol and a thiopental - low dose atracurium combination.

METHODS

In a randomized controlled double blind study, 120 premedicated patients were allocated into four groups. After pre-oxygenation, anesthesia was induced as follows: 1 microg x kg(-1) fentanyl, 2.5 mg x kg(-1) propofol (group I); 1 microg x kg(-1) fentanyl, 5 mg x kg(-1) thiopental (group II); 1 microg x kg(-1) fentanyl, 5 mg x kg(-1) thiopental, 0.05 mg x kg(-1) or 0.1 mg x kg(-1) atracurium (groups III and IV respectively). The LMA was inserted by a blinded anesthesiologist who also assessed the following insertion conditions on a three point scale; jaw relaxation, biting, gagging, coughing, presence of laryngospasm, adequacy of airway patency, number of attempts at insertion and overall insertion conditions.

RESULTS

There was no difference in insertion conditions between groups I, III and IV. Group II produced the worst overall conditions (P<0.05). There were no differences in hemodynamic changes and apnea times between all four groups.

CONCLUSION

The combination of fentanyl-thiopental with low dose atracurium (0.05 or 0.1 mg x kg(-1)) provided conditions comparable with those of propofol for LMA insertion.

Placement of left-sided double-lumen endobronchial tubes: comparison of clinical and fibreoptic-guided placement

We have compared a new intubation manoeuvre using a fibreoptic bronchoscope with conventional blind placement of a double-lumen tube. Thirty adult patients who presented for thoracoscopy requiring one-lung ventilation underwent endobronchial intubation with a double-lumen tube inserted either in the conventional blind way or using a fibreoptic bronchoscope. There were four misplacements of the double-lumen tube using the conventional method but none using the bronchoscope. In addition, the bronchoscope allowed more rapid intubation (mean 106 vs 347 s). The results suggest that the fibreoptic-guided method of inserting the double-lumen tube was a satisfactory alternative to the conventional one.

Cardiac arrest associated with sulprostone use during caesarean section

Sulprostone, a synthetic prostaglandin with potent uterotonic action, has been shown to have a low complication rate in a large series. We present a case in which a bolus intravenous injection of sulprostone 30 micrograms was administered to treat postpartum haemorrhage during caesarean section. The 38-year-old patient with no previous cardiac or smoking history developed complete heart block, ventricular fibrillation and subsequent asystole. Cardiopulmonary resuscitation was successful after 45 minutes. Post resuscitation there was no myocardial infarction and she had complete neurological recovery. We postulate that the bolus of sulprostone resulted in possible coronary spasm that resulted in cardiac arrest.

Predictors of long-term outcome in severe head injury

Severe head injury is associated with significant morbidity and mortality. We conducted a retrospective study to assess the long-term outcome of these patients using the Glasgow Outcome Score (GOS) and evaluate the variables that might predict outcome. Data were collected from all post-traumatic neurosurgical patients with severe head injury (Glasgow Coma Scale 8 or less) admitted to the Surgical Intensive Care Unit over a 29-month period. The long-term outcome was assessed one year after the injury by a telephone interview or a review of the hospital records. Seventy patients satisfied the criteria for the study. The male to female ratio was 9:1. The mean age of the patients was 37 (range 17 to 84) years. The overall mortality was 50%. Patients with a poor outcome (defined as GOS scores of 1 to 3) had a significantly higher mean age, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and a lower Glasgow Coma Scale than those with a good outcome (GOS 4 to 5). The APACHE II score correlated better with outcome than the Glasgow Coma Scale or age. The APACHE II score may be used to prognosticate the long-term outcome in severe head injury.

Small tubes revisited

We measured the peak inflation and end expiratory pressure at the proximal and distal ends of two sizes of tracheal tube in men and women receiving positive pressure ventilation. There was a statistically significant increase in proximal inflation pressure when the smaller size of tube (6.5 mm for men, 6.0 mm for women) was used. There was no increase in distal inflation or end expiratory pressures. Clinically satisfactory positive pressure ventilation was obtained when 6.0 and 6.5 mm tracheal tubes were used. The advantages and disadvantages of using small sizes of tracheal tube are discussed.

Distinguishing cerebrospinal fluid from saline used to identify the extradural space

Because of the potential seriousness of unrecognized dural puncture during the performance of extradural analgesia and the widespread use of normal saline for the "loss of resistance" technique, it is important to differentiate between cerebrospinal fluid (CSF) and saline dripping from the extradural needle. During insertion of lumbar drains in 10 neurosurgical patients, we first identified the extradural space using saline for loss of resistance. Temperature (using the back of the gloved hand), pH, glucose and protein (using urine testing sticks) were tested by a blinded observer for ability to distinguish saline aspirated from the extradural space from CSF aspirated on establishing the dural puncture. Temperature, glucose and protein were independently 100% accurate in distinguishing saline from CSF. One saline sample had a pH value greater than 7 compared with nine CSF samples. We conclude that simple bedside testing for temperature, glucose, protein and pH accurately distinguished between CSF and saline used to identify the extradural space.

Motor evoked potential monitoring during spinal surgery: responses of distal limb muscles to transcranial cortical stimulation with pulse trains

During spinal surgery, motor evoked potentials (MEPs) were recorded from distal upper and lower limb muscles following multipulse transcranial electrical stimulation of the cortex. Twenty-two patients, 9 of them myelopathic, were anaesthetised with propofol +/- nitrous oxide. Using trains of 3-6 pulses separated by 2 ms, consistent responses generally measuring more than 100 microV were obtained from every patient except one, and persisted with nitrous oxide concentrations as high as 74%. Responses could usually be elicited from 3 or more limbs simultaneously, although the location of the stimulating anode was sometimes critical. The lower limb responses of one patient disappeared transiently during excision of an intramedullary tumour; his leg weakness was increased for a few days after surgery. Three other patients experienced increased weakness or spasticity, two without concomitant MEP changes and one with no recordable responses. Although other methods may be preferable in some circumstances, we believe this represents an advance over previously reported non-invasive techniques for peroperative MEP monitoring, and may be particularly useful for monitoring patients with myelopathy in the thoracic region.

Rapid tracheal intubation with atracurium: the timing principle

The "Timing Principle" utilises a single bolus of non-depolarising neuromuscular blocking drug followed by thiopentone given at the onset of clinical weakness. The purpose of this study was to compare the intubating conditions after succinylcholine and after atracurium used according to the "timing principle." Eighty patients were randomly assigned to four groups of 20. Three study groups were given atracurium 0.5, 0.75 or 1 mg.kg-1 (Groups I, II and III respectively) and the control group (Group IV) received succinylcholine 1.5 mg.kg-1. The study groups received fentanyl 1 microgram.kg-1, atracurium three minutes later, followed by thiopentone 4-6 mg.kg-1 at the onset of ptosis. The control group had a defasciculating dose of atracurium (0.025 mg.kg-1) and fentanyl (1 microgram.kg-1) followed by thiopentone (4-6 mg.kg-1) and succinylcholine three minutes later. The trachea was intubated one minute after thiopentone was given. The intubating conditions were then graded by a laryngoscopist who was unaware of the induction sequence. All patients were interviewed on the day after surgery. Intubation scores of patients in Group I were worse than in Groups II, III and IV (P < 0.005) but there were no differences between Groups II, III and IV. The technique was not associated with severe haemodynamic changes. All patients, except one were able to cough well after administration of atracurium, before induction of anaesthesia with thiopentone. Patients were generally satisfied with this method of induction. It is concluded that atracurium, when used according to the timing principle, can be an alternative to succinylcholine during rapid-sequence induction.

Septic shock in a surgical intensive care--validation of multiorgan and APACHE II scores in predicting outcome

We analysed retrospectively the records of 353 admissions to the National University Hospital's Surgical Intensive Care Unit over a one-year period and found 25 patients with septicaemic shock requiring vasoactive therapy. The mortality rate was 68%. Blood cultures were positive in only 36%. We validated the ability of the Acute Organ System Failure score, Multiorgan Failure score, Organ System Failure score and Acute Physiology and Chronic Health Evaluation II (APACHE II) score to predict outcome at onset of septic shock. Only the APACHE II was a significant predictor of outcome, the rest having poor predictive ability. We conclude that the present scoring systems are too inaccurate for us to base important clinical decisions on.

Validation of APACHE II score in a surgical intensive care unit

The APACHE II scoring system was applied to 301 surgical intensive care admissions over a 9-month period. The mean age of patients admitted was 52.39 years (SD 19.3) and the mean duration of stay was 5.37 days (SD 8.93). The overall mortality was 17.27%. The mean APACHE II scores for survivors was 12.94 (SD 7.43) and non-survivors 28.19 (SD 10.43). There was good correlation between expected mortality predicted by the APACHE II system and observed mortality (r = 0.9732). Using a predicted risk criterion of 0.5 to distinguish between those predicted to survive and die, of the 45 patients predicted to die, only 30 actually did so. No patient survived with an APACHE II score of more than 40 and with a predicted risk of death greater than 0.87. We found the APACHE II system useful for evaluating ICU performance and risk stratification for the purpose of therapeutic trials but not as a triage tool.