A paediatric critical care transport service encountered elevated tracheal tube cuff pressures (>30 cmH20) in 41% of 60 consecutive care studied, and over 60 cmH20 in 30%. This measurement was taken on arrival at the bedside, not in flight.
Cuffed tubes are good, but we need to keep an eye on the pressures.
This is in keeping with the results of an adult study previously blogged on this site.
Endotracheal Tube Cuff Pressures in Pediatric Patients Intubated Before Aeromedical Transport
Pediatr Emerg Care. 2010 May;26(5):361-3
Tag Archives: airway
Alternative toothless mask position
An alternative position for holding the facemask when bag-mask ventilating edentulous patients is described and evaluated. 49 patients with inadequate seal and air leak during two-hand positive-pressure ventilation had significantly improved ventilation as measured by reduced air leak and increased expiratory volume when the caudal end of the mask was repositioned above the lower lip while maintaining neck extension.
Face mask ventilation in edentulous patients: a comparison of mandibular groove and lower lip placement
Anesthesiology. 2010 May;112(5):1190-3
Unexpected survivors after pre-hospital intubation
Data on patients with moderate to severe traumatic brain injury from the San Diego Trauma Registry were analysed using modified TRISS methodology to determine predicted survival, from which an observed-predicted survival differential (OPSD) was calculated. The mean OPSD was calculated as the primary outcome for the following comparisons: intubated versus nonintubated, air versus ground transport, eucapnia (PCO2 30–50 mm Hg) versus noneucapnia, and hypoxemia (PO<90 mm Hg) versus nonhypoxemia. Of note in this region is that ground EMS staff intubate without drugs, whereas air medical services use rapid sequence intubation with suxamethonium plus either etomidate or midazolam.
The rationale behind this methodology was to eliminate the possible selection bias present in previous studies linking pre-hospital intubation with mortality (sicker patients are able to be intubated without drugs).
A total of 9,018 TBI patients had complete data to allow calculation of probability of survival using TRISS. A total of 16.7% of patients were intubated in the field; 49.6% of these were transported by air medical providers. Patients undergoing prehospital intubation, transported by ground, with arrival eucapnia, and without arrival hypoxemia had higher mean OPSD values.
Intubated patients were more likely to be “unexpected survivors” and live to hospital discharge despite low predicted survival values; patients transported by air medical personnel had higher OPSD values and had a higher proportion of unexpected survivors. No statistically significant differences were observed between air- and ground-transported patients with regard to arrival PCO2 values arrival PO2 values.
Prehospital Airway and Ventilation Management: A Trauma Score and Injury Severity Score-Based Analysis
J Trauma. 2010 Aug;69(2):294-301
Mallampati assessment in ED airways
In a series of approximately 300 patients intubated in the ED, operators were unable to complete a Mallampati assessment in three quarters of them, citing lack of patient cooperation and critical illness as the main reasons. This is in keeping with work by Richard Levitan, lending further support to the lack of applicability of routine pre-operative airway assessment methods in critical care.
Feasibility of the preoperative Mallampati airway assessment in emergency department patients
J Emerg Med. 2010 Jun;38(5):677-8
Etomidate in RSI – systematic review
A systematic review of 20 included studies comparing a bolus dose of etomidate for rapid sequence induction with other induction agents resulted in the following conclusion:
“The available evidence suggests that etomidate suppresses adrenal function transiently without demonstrating a significant effect on mortality. However, no studies to date have been powered to detect a difference in hospital, ventilator, or ICU length of stay or in mortality”
The Effect of a Bolus Dose of Etomidate on Cortisol Levels, Mortality, and Health Services Utilization: A Systematic Review
Ann Emerg Med. 2010 Aug;56(2):105-13
Tracheal tube cuff pressure in flight
Tracheal tube cuff pressures increased from a mean 28.7 cm H2O pre-flight to 62.6 cm H2O in flight (mean altitude increase 2260 feet) in a Swiss helicopter-based study.
At cruising altitude, 98% of patients had intracuff pressure >30 cm H2O, 72% had intracuff pressure>50 cm H2O, and 20% even had intracuff pressure>80 cm H2O.
Multiple different referring hospitals meant the type of tracheal tube was not controlled for.
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Endotracheal Tube Intracuff Pressure During Helicopter Transport
Ann Emerg Med. 2010 Aug;56(2):89-93
Less RSI desaturation with Roc
Some of my pre-hospital critical care colleagues in the UK exclusively use rocuronium in preference to suxamethonium for rapid sequence induction (RSI) of anaesthesia in critically ill patients. I couldn’t see a good reason to switch although now there’s some evidence that adds to the argument.
The muscle fasciculations caused by the depolarising effect of suxamethonium may increase oxygen consumption, which may shorten the apnoea time before desaturation. Non-depolarising neuromuscular blockers such as rocuronium should allow a longer apnoea time after RSI. In addition, drugs which reduce fasciculations (such as lidocaine and fentanyl) should delay the the onset of desaturation when given prior to suxamethonium.
These hypotheses were tested in a blinded, randomised controlled trial in 60 ASA-1 or -2 patients, who were scheduled for elective surgery under general anaesthesia. All patients received 2mg/kg propofol. One group was randomised to receive suxamethonium 1.5 mg/kg, a second group received rocuronium 1mg/kg plus lidocaine 1.5mg/kg and fentanyl 2mcg/kg, and a third group was given suxamethonium 1.5 mg/kg plus lidocaine 1.5mg/kg and fentanyl 2mcg/kg. The facemask was removed 50 seconds after the neuromuscular blocker was given and patients were intubated; the tube was then left open to air until desaturation to 95% occurred, which was timed.
Desaturation occurred significantly sooner in the suxamethonium-only group, followed by the sux/lido/fentanyl group, followed by the roc/lido/fentanyl group.
Of course these results are not necessarily directly applicable to the critically ill patient, and in this study there was no direct comparison between induction agent + rocuronium only and induction agent + suxamethonium only. Nevertheless the argument that suxamethonium-induced muscle fasciculations contribute to an avoidable increase in oxygen consumption is persuasive.
Effect of suxamethonium vs rocuronium on onset of oxygen desaturation during apnoea following rapid sequence induction
Anaesthesia. 2010 Apr;65(4):358-61
Pre-hospital RSI successes
A couple of papers in Prehospital Emergency Care this month contribute to the pre-hospital airway management / rapid sequence intubation (RSI) literature.
Intensive physician oversight of a pre-hospital RSI program increased the prescription of post-intubation morphine and midazolam, and decreased vecuronium use, although did not significantly increase the successful intubation rate in a before-and-after study. There was also an improvement in patient selection for RSI.
Effect of intensive physician oversight on a prehospital rapid-sequence intubation program
Prehosp Emerg Care. 2010 Jul-Sep;14(3):310-6
A prospective study examined intubation success rates and peri-intubation hypoxaemia in critical care transport (CCT) services in North America, whose services are mainly crewed by registered nurses (RNs) and emergency medical technicians–paramedic (EMT-Ps).
There was a mixture of pre-hospital and interhospital work: 51.9% of the 603 patients studied were intubated at the trauma scene, 27% were intubated inside a hospital, and interestingly 21.1% were intubated inside a vehicle (most of which were helicopters).
Neuromuscular blockade was used to facilitate intubation in only 428 patients (71%). Endotracheal intubation (ETI) was successful in 582 patients (96.5% of 603, 95% CI 94.7-97.8%). There was a greater need (p < 0.001) for multiple attempts at ETI when CCT crews performed the procedure in transport (37.3%) as compared with rate of requirement for multiple ETI attempts while in hospital (16.6%) or on scene (19.4%). Logistic regression identified a three-fold increase in the odds of requiring multiple attempts for intratransport ETI as compared with in-hospital ETI (OR 3.0, 95 CI 1.7–5.2, p < 0.001). 21 patients (3.5%) could not be intubated by the CCT crews resulting in a number of different rescue modalities including 3 cricothyroidotomies. At least there were no unrecognised oesophageal intubations. There were low rates of new hypoxaemia but peri-ETI SpO2 was only recorded for 494 patients (82%).
Airway management success and hypoxemia rates in air and ground critical care transport: a prospective multicenter study
Prehosp Emerg Care. 2010 Jul-Sep;14(3):283
Pre-hospital RSI
Physicians from HEMS London document their experience of 400 pre-hospital rapid sequence induction / intubations. Their data are consistent with the experience of other similar services and with the emergency airway management literature in general:
- Failure to intubate is rare
- Removing cricoid pressure often improves the view
- A BURP manoeuvre can improve the view and facilitate intubation, but bimanual laryngoscopy / external laryngeal manipulation is better
- Having an SOP optimises first-pass success rate
Cricoid pressure and laryngeal manipulation in 402 pre-hospital emergency anaesthetics: Essential safety measure or a hindrance to rapid safe intubation?
Resuscitation 2010(81):810–816
Poor pre-hospital intubation success
A Scottish study of 628 pre-hospital intubation attempts in cardiac arrest patients records the rate of successful intubations, oesophageal intubations, and endobronchial intubations. Prehospital tracheal intubation was associated with decreased rates of survival to admission. This study has the limitations of a retrospective series but indirectly provides some further muscle to the supraglottic airway lobby.
Field intubation of cardiac arrest patients: a dying art?
Emerg Med J. 2010 Apr;27(4):321-3