Yearly Archives: 2011

All Updates, ICU, PHARM, Resus

Cuff pressures and tracheal injury

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We all intubate patients with cuffed tubes, but we’re far too busy and important to fart around measuring tracheal tube cuff pressures when we’re saving lives right? Surely something the ICU nurses can sort out between ‘eye care’ and swabbing for MRSA.
The modern ‘high volume low pressure’ cuff has certainly led us to worry less about cuff pressures, and in frontline critical care specialties like emergency medicine and pre-hospital and retrieval medicine it’s the last thing on our minds. However we should consider the accumulating pool of evidence that tells us:

  1. Physicians are hopelessly poor at estimating cuff pressures based on palpating the pilot balloon
  2. Cuff pressures are frequently very high
  3. Tracheal mucosal injury can occur even after short term intubation (a few hours)
  4. When the pressure in the cuff exceeds 22 mm Hg, blood flow in the tracheal mucosa begins decreasing
  5. Tracheal mucosal blood flow reduces markedly when the pressure reaches 30 mm Hg
  6. When the pressure in the cuff reaches 50 mm Hg for 15 minutes, ischemic injury to the tracheal mucosa can occur

Patchy hemorrhagic ulceration in tracheal mucosa

A study from China tested the hypothesis that an appropriate tracheal tube cuff (ETTc) pressure even in short procedures would reduce endotracheal intubation–related morbidity. They compared bronchoscopic appearance of tracheal mucosa, and patient symptoms of tracheal injury, in two groups of elective surgical patients anaesthetised and intubated between 120 and 180 minutes: a control group without measuring ETTc pressure, and a study group with ETTc pressure measured and adjusted to a range 15-25 mmHg. The endoscopist was blinded to the study group allocation.

The mean ETTc pressure measured after estimation by palpation of the pilot balloon of the study group was 43 +/- 23.3 mm Hg before adjustment (the highest was 210 mm Hg), and 20+/- 3.1 mm Hg after adjustment (p< 0.001). The incidence of postprocedural sore throat, hoarseness, and blood-streaked expectoration in the control group was significantly higher than in the study group. As the duration of endotracheal intubation increased, the incidence of sore throat and blood-streaked expectoration in the control group increased. The incidence of sore throat in the study group also increased with increasing duration of endotracheal intubation. Fiberoptic bronchoscopy showed that the tracheal mucosa was injured in varying degrees in both groups, but the injury was more severe in the control group than in the study group.
So..time to get a cuff manometer for your ED or helicopter? Perhaps you already have one. What do you think?
Correlations Between Controlled Endotracheal Tube Cuff Pressure and Postprocedural Complications: A Multicenter Study
Anesth Analg. 2010 Nov;111(5):1133-7
Related posts:
Cuff pressure in flight
Paediatric cuff pressures

All Updates, ICU, Kids, PHARM

Better outcome with paediatric retrieval teams

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Data from the England and Wales Paediatric Intensive Care Audit Network on children (aged 16 years or younger) admitted to 29 regional paediatric intensive care units (PICUs) between 1 January 2005 and 31 December 2008 were analysed in a retrospective cohort study to assess the effectiveness of the specialist retrieval teams.

The type of transferring team (specialist or non-specialist) was known for 16 875 cases and was specialist in 13 729 (81%). Compared with children transferred to PICUs from within the same hospital, children transferred from other hospitals were younger (median age 10 months vs 18 months), more acutely ill (mortality risk 6% vs 4% using the Paediatric Index of Mortality), needed more resources (such as invasive ventilation, vasoactive drugs, renal replacement therapy, extracorporeal membrane oxygenation and/or multiple-organ support), had longer stays in the PICU (median 75 h vs 43 h) and had a higher crude mortality (8% vs 6%). On multivariable analysis after adjustment for case mix and organisational factors, the risk of death among interhospital transfers was significantly (35%) lower than among intrahospital transfers. With similar analysis, the times spent in PICU did not differ significantly between these two groups. When the type of transferring team was considered, crude mortality was similar with specialist and non-specialist teams, although the children transferred by the specialist teams were more severely ill. On multivariable analysis, the risk of death was 42% lower with specialist team transfer.
These findings appear to confirm the value of specialist retrieval teams. Why children transferred from other hospitals did better than children transferred to the PICU in the same hospital is not explained.
Effect of specialist retrieval teams on outcomes in children admitted to paediatric intensive care units in England and Wales: a retrospective cohort study
Lancet. 2010 Aug 28;376(9742):698-704

All Updates, ICU, PHARM, Resus, Trauma

Less smelly than chicken drumsticks

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Emergency and orthopaedic doctors Elizabeth and Anthony Bateman from Britain describe their method of making a bone simulator for intraosseous cannulation training:

  • Take up to one Crunchie bar per trainee (leave in wrapper!) – this simulates the cancellous bone that is cannulated.
  • Tightly plaster cast with four layers of polyester cast tape (12.5 cm width matches closely to Crunchie bar length), cutting lengths of the cast tape as needed prior to immersing in water – this simulates the hard cortical bone.
  • Foam padding, or two layers of wool band from the plaster room, can be added to simulate soft tissue.


A quick google reveals it can be a challenge getting Crunchie bars in the United States. Maybe there’s a suitable honeycomb-centred alternative. If not you can resort to ordering them from Amazon.
Intraosseus access simulation: the Crunchie solution
Emerg Med J. 2010 Dec;27(12):961

All Updates, ICU, Resus, Trauma

Intubating spinal patients – the haemodynamics

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Laryngoscopy and tracheal intubation transiently increase arterial pressure, heart rate (HR), and circulating catecholamines, in part attributed to reflex sympathetic discharge. In a complete spinal cord injury, the sympathetic nervous system and hence the cardiovascular responses to the intubation may be differentially affected according to the level of injury. Patients with acute quadriplegia often have a low resting arterial pressure due to inappropriate vasodilatation and loss of cardiac inotropy. Moreover, they frequently exhibit arrhythmias, reflex bradycardia, and cardiac arrest, especially during tracheal suction. In the days to weeks after injury, however, the reflex functioning of the lower cord recovers to maintain normal vascular tone. In the chronic stage, peripheral vascular changes and a loss of descending inhibitory control result in paroxysmal hypertension.
Korean investigators KY Yoo and colleagues1 aimed to determine the effect of the level (quadriplegia vs paraplegia) and duration of spinal cord injury on haemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with spinal cord injury. The outcome measures were the changes in systolic arterial pressure (SAP), HR, and catecholamine levels above awake baseline values after intubation.
Patients were divided into two groups: quadriplegia (above C7) and paraplegia (below T5). Each group was divided into six subgroups according to the time elapsed after the injury: <4 weeks (acute), 4 weeks– 1 yr, 1–5, 5–10, 10–20, and >20 yr. Twenty non-disabled patients undergoing surgery requiring tracheal intubation served as controls.
Patients with high-level paraplegia (T1–T4) were excluded because they were few in number and they had previously ‘shown different haemodynamic and catecholamine responses from the other groups‘ 2 which refers to work published by the same authors, in which high-paraplegic patients had a more pronounced increase in heart rate compared with other groups. Confusingly the ‘patients who were at increased risk of hyperkalemia after succinylcholine were excluded‘ although this statement appears only in the discussion, not the methods.
Anaesthesia was induced with sodium thiopental 5 mg/kg administered i.v. over 20 s, followed by succinylcholine 1 mg/kg for 5 s, and was followed by direct laryngoscopy and tracheal intubation.
Results were as follows:

  • SAP decreased after the induction of anaesthesia with thiopental in all subjects including the controls (P<0.05).
  • SAP then increased in response to tracheal intubation in the control and paraplegics (P<0.001), whereas it remained unaltered in the quadriplegics regardless of the time since injury.
  • In the paraplegics, the magnitude of maximum increase from baseline values was similar within 10 yr of injury, but was higher thereafter compared with that in the controls (P<0.05).
  • The maximum increase in SAP from baseline values after tracheal intubation was greater in the paraplegics than in the quadriplegics (P<0.0001).

  • An increase in SAP.130% of preinduction baseline values or 160 mm Hg was noted in three (4.2%) of 71 quadriplegics and 94 (65.7%) of 143 paraplegics.
  • The incidence of hypertension was significantly lower and that of hypotension significantly higher in the quadriplegics than in the control.
  • HR increased after induction ofanaesthesia in all groups, but less so in the quadriplegic groups.
  • Although baseline bradycardia was common in the acute quadriplegics, none of them showed further slowing during induction of anaesthesia and tracheal intubation.
  • Tracheal intubation increased plasma norepinephrine concentrations in all subjects except the acute quadriplegics.
  • Epinephrine concentrations were not significantly different between before and after intubation either in the quadriplegics or in the paraplegics, nor were they different between the groups with regard to the duration of injury.

    • The authors summarise: The pressor response was abolished in all quadriplegics regardless of the time elapsed after the injury. In contrast, the chronotropic and catecholamine responses differed over time. The chronotropic response was attenuated and the catecholamine response abolished in the acute quadriplegics. The chronotropic and catecholamine responses were improved in the quadriplegics after 4 weeks since the injury. In the paraplegic patients, cardiovascular responses did not change in the 10 yr after injury and the pressor response was enhanced at 10 yr or more after injury.
    1.Altered cardiovascular responses to tracheal intubation in patients with complete spinal cord injury: relation to time course and affected level
    Br J Anaesth. 2010 Dec;105(6):753-9
    2. Hemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with complete spinal cord injuries.
    Anesthesiolgy 2001; 95: 647–51