Time to change thinking on ‘cricoid pressure’

April 22, 2014 by  
Filed under All Updates

I don’t like cricoid pressure. Some people do. There is insufficient evidence that it is of any benefit. There is some consistent evidence that it worsens laryngoscopic view.

In my clinical practice of critical care in and out of hospital, I can’t afford to risk delaying the securing of my patients’ airways with a procedure in which in my view the risks of harm outweigh any unproven chance of benefit.

I had erroneously thought after many online ‘debates’ that the critical care community had settled on a compromise – if you want to use it great, just take it off if it’s causing a problem. If you don’t want to use it, then that’s equally fine.

However a Google Plus conversation last week ignited a storm! There was a suggestion that cricoid pressure represented a ‘standard of care’, and that not to use it in a critical care intubation would potentially invite legal proceedings, catalysed by colleagues prepared to testify against those of us who have carefully weighed the balance of evidence and selected what we feel is the best approach for our patients.

I wrote a post to challenge the very thinking that what might be considered a ‘standard of care’ in elective anaesthesia in some guidelines should ever be applied to a critical care airway. I proposed a tongue in cheek change of terminology to emphasis what we know about cricoid pressure in the critically ill: that it can delay intubation, distort and compress the airway, and move rather than compress the oesophagus (although I concede the latter point may be irrelevant in terms of CP’s proposed mechanism).

Some people got upset. I reworded the post and added a big fat disclaimer to avoid any perception of ad hominen attack. I wanted to attack and ridicule the procedure, not its proponents. I still got attacked using some bizarrely offensive comparisons by people you would expect to know better. It got ugly.

The combination of support by some people I hold in very high regard and a currently crazy schedule (I’ve been in the UK for three hours having just travelled from Australia) meant the post stayed up for a while until I could consider the feedback. I still haven’t read it all. But I’ve read enough.

I respect the people I disagree with. I respect absolutely their right to hold different views from my own. But I don’t respect all their views, and I don’t necessarily think people have a right not to be offended by my views. However if the WAY I EXPRESS those views causes UNNECESSARY offence I have to reconsider my message.

The science around cricoid pressure is there in the literature. The arguments that it can acceptably be discarded in critical care are powerful. If we need a new acronym it doesn’t need to be one that can be pronounced and construed in a way different to that which I’d envisaged. As Dr Brent May so insightfully put: ‘You can’t emphasise a syllable on Twitter‘.

I want to thank EVERYONE who provided constructive feedback on and off social media. I apologise unreservedly to anyone offended by the post. It’s gone. The battle against unthinking enforcement of a potentially harmful technique goes on, but the unwitting offence of innocent parties is not an acceptable consequence. I will try to be more intelligent in subsequent debate.

Cliff

Breaking with tradition in paediatric RSI

April 8, 2014 by  
Filed under All Updates, EMS, ICU, Kids, Resus

‘Traditional’ rapid sequence induction of anaesthesia is often described with inclusion of cricoid pressure and the strict omission of any artifical ventilation between paralytic drug administration and insertion of the tracheal tube. These measures are aimed at preventing pulmonary aspiration of gastric contents although there is no convincing evidence base to support that. However it is known that cricoid pressure can worsen laryngoscopic view and can occlude the paediatric airway. We also know that children desaturate quickly after the onset of apnoea, and although apnoeic diffusion oxygenation via nasal cannula can prevent or delay that, in some cases it may be preferable to bag-mask ventilate the patient while awaiting full muscle relaxation for laryngoscopy.

A Swiss study looked at 1001 children undergoing RSI for non-cardiac surgery. They used a ‘controlled rapid sequence induction and intubation (cRSII)’ approach for children assumed to have full stomachs. This procedure resembled RSI the way it is currently done in many modern critical care settings, including the retrieval service I work for:

  • No cricoid pressure
  • Ketamine for induction if haemodynamically unstable
  • A non-depolarising neuromuscular blocker rather than succinylcholine
  • No cricoid pressure
  • Gentle facemask ventilation to maintain oxygenation until intubation conditions achieved
  • Intubation with a cuffed tracheal tube
  • Still no cricoid pressure

The authors comment:

The main finding was that cRSII demonstrated a considerably lower incidence of oxygen desaturation and consecutive hemodynamic adverse events during anesthesia induction than shown by a previous study on classic RSII in children. Furthermore, there was no incidence of pulmonary aspiration during induction, laryngoscopy, and further course of anesthesia.

Looks like more dogma has been lysed, and this study supports the current trajectory away from traditional teaching towards an approach more suitable for critically ill patients.

Controlled rapid sequence induction and intubation – an analysis of 1001 children
Paediatr Anaesth. 2013 Aug;23(8):734-40


BACKGROUND: Classic rapid sequence induction puts pediatric patients at risk of cardiorespiratory deterioration and traumatic intubation due to their reduced apnea tolerance and related shortened intubation time. A ‘controlled’ rapid sequence induction and intubation technique (cRSII) with gentle facemask ventilation prior to intubation may be a safer and more appropriate approach in pediatric patients. The aim of this study was to analyze the benefits and complications of cRSII in a large cohort.

METHODS: Retrospective cohort analysis of all patients undergoing cRSII according to a standardized institutional protocol between 2007 and 2011 in a tertiary pediatric hospital. By means of an electronic patient data management system, vital sign data were reviewed for cardiorespiratory parameters, intubation conditions, general adverse respiratory events, and general anesthesia parameters.

RESULTS: A total of 1001 patients with cRSII were analyzed. Moderate hypoxemia (SpO2 80-89%) during cRSII occurred in 0.5% (n = 5) and severe hypoxemia (SpO2 <80%) in 0.3% of patients (n = 3). None of these patients developed bradycardia or hypotension. Overall, one single gastric regurgitation was observed (0.1%), but no pulmonary aspiration could be detected. Intubation was documented as ‘difficult’ in two patients with expected (0.2%) and in three patients with unexpected difficult intubation (0.3%). The further course of anesthesia as well as respiratory conditions after extubation did not reveal evidence of ‘silent aspiration’ during cRSII.

CONCLUSION: Controlled RSII with gentle facemask ventilation prior to intubation supports stable cardiorespiratory conditions for securing the airway in children with an expected or suspected full stomach. Pulmonary aspiration does not seem to be significantly increased.

Palpating neonatal tracheal tubes

April 6, 2014 by  
Filed under All Updates, EMS, ICU, Kids, Resus

Comments Off

infant-intubate-iconAfter neonatal intubation, the incidence of malposition of the tip of the tracheal tube is fairly high.

A technique was evaluated involving palpation of the tube tip in the suprasternal notch, which in this small study was superior to insertion length based on a weight-based nomogram.

The suprasternal notch was chosen because it anatomically corresponds to vertebral level T2, close to the optimal position at the mid-tracheal point. Correct position on the chest radiograph was defined as any position <0.5 cm above the interclavicular midpoint and more than 1 cm above the carina.

During tracheal tube placement, the tip was gently palpated in the suprasternal notch with the index or little finger of the left hand while holding the body of the tube with the fingers of the right hand. The tube tip was adjusted until the bevelled edge was just palpable in the the suprasternal notch.

Digital palpation of endotracheal tube tip as a method of confirming endotracheal tube position in neonates: an open-label, three-armed randomized controlled trial.
Paediatr Anaesth. 2013 Oct;23(10):934-9


OBJECTIVE: To compare the malposition rates of endotracheal tubes (ETTs) when the insertional length (IL) is determined by a weight-based nomogram versus when IL is determined by palpation of the ETT tip.

DESIGN: Open-label, randomized controlled trial (RCT).

SETTING: Level III neonatal intensive care unit (NICU).

SUBJECTS: All newborn babies admitted in NICU requiring intubation.

INTERVENTIONS: Subjects were randomly allocated to one of three groups, wherein IL was determined by (i) weight-based nomogram alone, (ii) weight-based nomogram combined with suprasternal palpation of ETT tip performed by specially trained neonatology fellows, or (iii) combination of weight-based and suprasternal methods by personnel not specially trained.

PRIMARY OUTCOME: Rate of malposition of ETT as judged on chest X-ray (CXR).

RESULTS: Fifty seven babies were randomized into group 1(n = 15), group 2 (n = 20), and group 3 (n = 22). The proportion of correct ETT placement was highest in group 2, being 66.7%, 83.3%, and 66.7% in groups 1 through 3, respectively (P value = 0.58). No complication was attributable to palpation technique.

CONCLUSION: Suprasternal palpation shows promise as a simple, safe, and teachable method of confirming ETT position in neonates.

Atropine for Paediatric RSI?

April 5, 2014 by  
Filed under All Updates, EMS, ICU, Kids, Resus

Comments Off

paedRSIdrugiconIn some areas it has been traditional to pre-medicate or co-medicate with atropine when intubating infants and children, despite a lack of any evidence showing benefit. It is apparently still in the American Pediatric Advanced Life Support (PALS) Provider Manual when age is less than 1 year or age is 1–5 years and receiving succinylcholine. However it is not recommended with rapid sequence intubation in the British and Australasian Advanced Paediatric Life Support manual and course.

A French non-randomised observational study compares intubations with and without atropine in the neonatal and paediatric critical care setting. Atropine use was associated with significant acceleration of heart rate, and no atropine use was associated with a higher incidence of new dysrhythmia, the most common being junctional rhythm, but with none appearing to be clinically significant.

The incidence of the most important peri-intubation cause of bradycardia – hypoxia – is not reported. It is also not clear how many intubation attempts were required. The authors admit:

it is not possible using our methodology to deduce whether bradycardia was due to hypoxia, laryngoscopy, or sedation drugs.

Actual rapid sequence was rarely employed – their use of muscle relaxants was low – making this difficult to extrapolate to modern emergency medicine / critical care practice.

My take home message here is that this study provides no argument whatsoever for the addition of atropine in routine RSI in the critically ill child. Why complicate a procedure with an unnecessary tachycardia-causing drug when the focus should be on no desat / no hypotension / first look laryngoscopy?

The Effect of Atropine on Rhythm and Conduction Disturbances During 322 Critical Care Intubations
Pediatr Crit Care Med. 2013 Jul;14(6):e289-97


OBJECTIVES: Our objectives were to describe the prevalence of arrhythmia and conduction abnormalities before critical care intubation and to test the hypothesis that atropine had no effect on their prevalence during intubation.

DESIGN: Prospective, observational study.

SETTING: PICU and pediatric/neonatal intensive care transport.

SUBJECTS: All children of age less than 8 years intubated September 2007-2009. Subgroups of intubations with and without atropine were analyzed.

INTERVENTION: None.

MEASUREMENT AND MAIN RESULTS: A total of 414 intubations were performed in the study period of which 327 were available for analysis (79%). Five children (1.5%) had arrhythmias prior to intubation and were excluded from the atropine analysis. Atropine was used in 47% (152/322) of intubations and resulted in significant acceleration of heart rate without provoking ventricular arrhythmias. New arrhythmias during intubation were related to bradycardia and were less common with atropine use (odds ratio, 0.14 [95% CI, 0.06-0.35], p < 0.001). The most common new arrhythmia was junctional rhythm. Acute bundle branch block was observed during three intubations; one Mobitz type 2 rhythm and five ventricular escape rhythms occurred in the no-atropine group (n = 170). Only one ventricular escape rhythm occurred in the atropine group (n = 152) in a child with an abnormal heart. One child died during intubation who had not received atropine.

CONCLUSIONS: Atropine significantly reduced the prevalence of new arrhythmias during intubation particularly for children over 1 month of age, did not convert sinus tachycardia to ventricular tachycardia or fibrillation, and may contribute to the safety of intubation.

Resus Team Size and Productivity

April 3, 2014 by  
Filed under All Updates, Kids, Resus, Trauma

paedsimiconA paediatric trauma centre study showed that in their system, seven people at the bedside was the optimum number to get tasks done in a paediatric resuscitation. As numbers increased beyond this, there were ‘diminishing marginal returns’, ie. the output (tasks completed) generated from an additional unit of input (extra people) decreases as the quantity of the input rises.

The authors comment that after a saturation point is reached, “additional team members contribute negative returns, resulting in fewer tasks completed by teams with the most members. This pattern has been demonstrated in other medical groups, with larger surgical teams having prolonged operative times and larger paramedic crews delaying the performance of cardiopulmonary resuscitation.

There are several possible explanations:

  • crowding limits access to the patient or equipment;
  • “social loafing”- staff may feel less accountable for the overall group performance and less pressure to accomplish individual tasks;
  • seven is the number recommended in that institution’s trauma activation protocol, with optimal role allocation described for a team of that size;
  • teams with redundant personnel may experience role confusion and fragmentation, resulting in both repetition and omission of tasks.

In my view, excessive team size results in there being more individuals to supervise & monitor, and hence a greater cognitive load for the team leader (cue the resus safety officer). More crowding and obstruction threatens situational awareness. There is more difficulty in providing clear uninterrupted closed loop communication. And general resuscitation room entropy increases, requiring more energy to contain or reverse it.

However, for paediatric resuscitations requiring optimal concurrent activity to progress the resuscitation, I do struggle with less than five. Unless of course I’m in my HEMS role, when the paramedic and I just crack on.

More on Making Things Happen in resus.

Own The Resus talk

Resus Room Management site

Factors Affecting Team Size and Task Performance in Pediatric Trauma Resuscitation.
Pediatr Emerg Care. 2014 Mar 19. [Epub ahead of print]


OBJECTIVES: Varying team size based on anticipated injury acuity is a common method for limiting personnel during trauma resuscitation. While missing personnel may delay treatment, large teams may worsen care through role confusion and interference. This study investigates factors associated with varying team size and task completion during trauma resuscitation.

METHODS: Video-recorded resuscitations of pediatric trauma patients (n = 201) were reviewed for team size (bedside and total) and completion of 24 resuscitation tasks. Additional patient characteristics were abstracted from our trauma registry. Linear regression was used to assess which characteristics were associated with varying team size and task completion. Task completion was then analyzed in relation to team size using best-fit curves.

RESULTS: The average bedside team ranged from 2.7 to 10.0 members (mean, 6.5 [SD, 1.7]), with 4.3 to 17.7 (mean, 11.0 [SD, 2.8]) people total. More people were present during high-acuity activations (+4.9, P < 0.001) and for patients with a penetrating injury (+2.3, P = 0.002). Fewer people were present during activations without prearrival notification (-4.77, P < 0.001) and at night (-1.25, P = 0.002). Task completion in the first 2 minutes ranged from 4 to 19 (mean, 11.7 [SD, 3.8]). The maximum number of tasks was performed at our hospital by teams with 7 people at the bedside (13 total).

CONCLUSIONS: Resuscitation task completion varies by team size, with a nonlinear association between number of team members and completed tasks. Management of team size during high-acuity activations, those without prior notification, and those in which the patient has a penetrating injury may help optimize performance.

High Flow Nasal Cannulae In Paediatric Retrieval

April 2, 2014 by  
Filed under All Updates, EMS, ICU, Kids

Comments Off

High Flow Nasal Cannulae (HFNC) oxygen therapy was introduced in paediatric interfacility retrievals undertaken by the Mater Children’s PICU Retrieval Team in Queensland, Australia. In 793 under 2 year olds, HFNC was associated with a reduction in infants receiving invasive or non-invasive ventilation. 77% of the patients had bronchiolitis.

The rationale for this treatment is explained as:

Owing to the inherent properties of the infant respiratory system with small airways and high chest compliance, the risk of developing atelectasis is high in bronchiolitis. HFNC therapy applied early in the disease process may prevent progression of the disease and maintain normal lung volumes, thereby preventing atelectasis. As a result, the functional residual capacity can be maintained and work of breathing reduced, which may stabilize the patient sufficiently to avoid the need for intubation. For this purpose we used flow rates of 2 L/kg/min which have been shown to result in a positive end-expiratory pressure of 4–5 cmH2O

Read more on high-flow nasal cannula oxygen therapy.

High-flow nasal cannula (HFNC) support in interhospital transport of critically ill children
Intensive Care Med. 2014 Feb 15. [Epub ahead of print]


BACKGROUND: Optimal respiratory support for interhospital transport of critically ill children is challenging and has been scarcely investigated. High-flow nasal cannula (HFNC) therapy has emerged as a promising support mode in the paediatric intensive care unit (PICU), but no data are available on HFNC used during interhospital transport. We aimed to assess the safety of HFNC during retrievals of critically ill children and its impact on the need for invasive ventilation (IV).

METHODS: This was a retrospective, single-centre study of children under 2 years old transported by a specialized paediatric retrieval team to PICU. We compared IV rates before (2005-2008) and after introduction of HFNC therapy (2009-2012).

RESULTS: A total of 793 infants were transported. The mean transport duration was 1.4 h (range 0.25-8), with a mean distance of 205 km (2-2,856). Before introduction of HFNC, 7 % (n = 23) were retrieved on non-invasive ventilation (NIV) and 49 % (n = 163) on IV. After introduction of HFNC, 33 % (n = 150) were retrieved on HFNC, 2 % (n = 10) on NIV, whereas IV decreased to 35 % (n = 162, p < 0.001). No patients retrieved on HFNC required intubation during retrieval, or developed pneumothorax or cardiac arrest. Using HFNC was associated with a significant reduction in IV initiated by the retrieval team (multivariate OR 0.51; 95 % CI 0.27-0.95; p = 0.032).

CONCLUSIONS: We report on a major change of practice in transport of critically ill children in our retrieval system. HFNC therapy was increasingly used and was not inferior to low-flow oxygen or NIV. Randomized trials are needed to assess whether HFNC can reduce the need for IV in interhospital transport of critically ill children.

Blood pressure target in septic shock

April 1, 2014 by  
Filed under Acute Med, All Updates, ICU, Resus

Comments Off

ABP-iconA study comparing mean arterial pressure (MAP) targets of 80 to 85 mm Hg (high-target group) with 65 to 70 mm Hg (low-target group) n 776 septic shock patients – the SEPSISPAM study – did not show a difference in the primary endpoint of 28 day mortality. Among patients with chronic hypertension, those in the high-target group required less renal-replacement therapy than did those in the low-target group. In my view this supports an approach that targets MAP based on the individual patient’s history rather than a blanket one-number-fits-all approach. The MAPs actually achieved in the low-target group were between 70-75 mm of Hg.

For a more thorough review check out the great PulmCCM blog.

High versus Low Blood-Pressure Target in Patients with Septic Shock.
N Engl J Med. 2014 Mar 18. [Epub ahead of print] Free Full Text


Background: The Surviving Sepsis Campaign recommends targeting a mean arterial pressure of at least 65 mm Hg during initial resuscitation of patients with septic shock. However, whether this blood-pressure target is more or less effective than a higher target is unknown.

Methods: In 31 emergency departments in the United States, we randomly assigned patients with septic shock to one of three groups for 6 hours of resuscitation: protocol-based EGDT; protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions; or usual care. The primary end point was 60-day in-hospital mortality. We tested sequentially whether protocol-based care (EGDT and standard-therapy groups combined) was superior to usual care and whether protocol-based EGDT was superior to protocol-based standard therapy. Secondary outcomes included longer-term mortality and the need for organ support.

Results: At 28 days, there was no significant between-group difference in mortality, with deaths reported in 142 of 388 patients in the high-target group (36.6%) and 132 of 388 patients in the low-target group (34.0%) (hazard ratio in the high-target group, 1.07; 95% confidence interval [CI], 0.84 to 1.38; P=0.57). There was also no significant difference in mortality at 90 days, with 170 deaths (43.8%) and 164 deaths (42.3%), respectively (hazard ratio, 1.04; 95% CI, 0.83 to 1.30; P=0.74). The occurrence of serious adverse events did not differ significantly between the two groups (74 events [19.1%] and 69 events [17.8%], respectively; P=0.64). However, the incidence of newly diagnosed atrial fibrillation was higher in the high-target group than in the low-target group. Among patients with chronic hypertension, those in the high-target group required less renal-replacement therapy than did those in the low-target group, but such therapy was not associated with a difference in mortality.

Conclusions: Targeting a mean arterial pressure of 80 to 85 mm Hg, as compared with 65 to 70 mm Hg, in patients with septic shock undergoing resuscitation did not result in significant differences in mortality at either 28 or 90 days.

No Benefit From Early Goal Directed Therapy

March 19, 2014 by  
Filed under Acute Med, All Updates, Guidelines, ICU, Resus

The first of three major trials assessing early goal directed therapy (EGDT) in sepsis – the American ProCESS Trial – has been published.

It showed what many of us thought – that the specific monitoring via a central line of central venous oxygen saturation – was not necessary for improved survival.

However the trial randomised 1341 patients to one of three arms:
(1) protocolised EGDT
(2) protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions
(3) ‘usual care’ which was not standardised.

There were no differences in any of the primary or secondary outcomes between the groups.

Interestingly, in the six hours of early care that the trial dictated, the volume of intravenous fluids administered differed significantly among the groups (2.8 litres in the protocol-based EGDT group, 3.3 litres in the protocol-based standard-therapy group, and 2.3 litres in the usual-care group).

There was also a difference in the amount of vasopressor given, with more patients in the two protocol-based groups receiving vasopressors (54.9% in the protocol-based EGDT group, 52.2% in the protocol-based standard-therapy group, 44.1% in the usual-care group).

The use of intravenous fluids, vasopressors, dobutamine, and blood transfusions between 6 and 72 hours did not differ significantly among the groups.

Overall 60 day mortality was in the region of 20% for all groups.

What are the take home points here? Firstly, overall sepsis outcomes have improved over recent years, and early recognition and antibiotic administration may be the most important components of care. In the early emergency department phase of care, protocolised fluid and vasopressor therapy may not be as important as we thought. Good clinical assessment and regular review seem to be as effective and perhaps more important than any specific monitoring modality or oxygen delivery-targeted drug and blood therapy.

We all await the ARISE and ProMISE studies which may shed more light on the most important components of early sepsis care.

A Randomized Trial of Protocol-Based Care for Early Septic Shock
NEJM Mar 18 2014 (Full Text Link)


Background: In a single-center study published more than a decade ago involving patients presenting to the emergency department with severe sepsis and septic shock, mortality was markedly lower among those who were treated according to a 6-hour protocol of early goal-directed therapy (EGDT), in which intravenous fluids, vasopressors, inotropes, and blood transfusions were adjusted to reach central hemodynamic targets, than among those receiving usual care. We conducted a trial to determine whether these findings were generalizable and whether all aspects of the protocol were necessary.

Methods: In 31 emergency departments in the United States, we randomly assigned patients with septic shock to one of three groups for 6 hours of resuscitation: protocol-based EGDT; protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions; or usual care. The primary end point was 60-day in-hospital mortality. We tested sequentially whether protocol-based care (EGDT and standard-therapy groups combined) was superior to usual care and whether protocol-based EGDT was superior to protocol-based standard therapy. Secondary outcomes included longer-term mortality and the need for organ support.

Results: We enrolled 1341 patients, of whom 439 were randomly assigned to protocol-based EGDT, 446 to protocol-based standard therapy, and 456 to usual care. Resuscitation strategies differed significantly with respect to the monitoring of central venous pressure and oxygen and the use of intravenous fluids, vasopressors, inotropes, and blood transfusions. By 60 days, there were 92 deaths in the protocol-based EGDT group (21.0%), 81 in the protocol-based standard-therapy group (18.2%), and 86 in the usual-care group (18.9%) (relative risk with protocol-based therapy vs. usual care, 1.04; 95% confidence interval [CI], 0.82 to 1.31; P=0.83; relative risk with protocol-based EGDT vs. protocol-based standard therapy, 1.15; 95% CI, 0.88 to 1.51; P=0.31). There were no significant differences in 90-day mortality, 1-year mortality, or the need for organ support.

Conclusions: In a multicenter trial conducted in the tertiary care setting, protocol-based resuscitation of patients in whom septic shock was diagnosed in the emergency department did not improve outcomes

Use a table for selecting PEEP in ARDS

March 13, 2014 by  
Filed under Acute Med, All Updates, ICU, Resus

Comments Off

PEEPtable.001Selecting the right amount of PEEP to recruit collapsed alveoli in patients with ARDS is important but the best method isn’t proven. Using a table to select PEEP based on FiO2 was significantly but weakly associated with improved lung recruitability (on CT scan) when compare with other methods of selecting PEEP, and was the best method for avoiding higher PEEP in patients with lower recruitability.

This is a small study and the results do not necessarily translate to improved clinical outcomes, but they may be of interest to emergency and retrieval medicine physicians who require a simple and safe strategy when managing ARDS patients without the luxury of time or of access to highly sophisticated ICU ventilators.

Bedside selection of positive end-expiratory pressure in mild, moderate, and severe acute respiratory distress syndrome
Crit Care Med. 2014 Feb;42(2):252-64


OBJECTIVE: Positive end-expiratory pressure exerts its effects keeping open at end-expiration previously collapsed areas of the lung; consequently, higher positive end-expiratory pressure should be limited to patients with high recruitability. We aimed to determine which bedside method would provide positive end-expiratory pressure better related to lung recruitability.

DESIGN: Prospective study performed between 2008 and 2011.
SETTING: Two university hospitals (Italy and Germany).

PATIENTS: Fifty-one patients with acute respiratory distress syndrome.

INTERVENTIONS: Whole lung CT scans were taken in static conditions at 5 and 45 cm H2O during an end-expiratory/end-inspiratory pause to measure lung recruitability. To select individual positive end-expiratory pressure, we applied bedside methods based on lung mechanics (ExPress, stress index), esophageal pressure, and oxygenation (higher positive end-expiratory pressure table of lung open ventilation study).

MEASUREMENTS AND MAIN RESULTS: Patients were classified in mild, moderate and severe acute respiratory distress syndrome. Positive end-expiratory pressure levels selected by the ExPress, stress index, and absolute esophageal pressures methods were unrelated with lung recruitability, whereas positive end-expiratory pressure levels selected by the lung open ventilation method showed a weak relationship with lung recruitability (r = 0.29; p < 0.0001). When patients were classified according to the acute respiratory distress syndrome Berlin definition, the lung open ventilation method was the only one which gave lower positive end-expiratory pressure levels in mild and moderate acute respiratory distress syndrome compared with severe acute respiratory distress syndrome (8 ± 2 and 11 ± 3 cm H2O vs 15 ± 3 cm H2O; p < 0.05), whereas ExPress, stress index, and esophageal pressure methods gave similar positive end-expiratory pressure values in mild, moderate, and severe acute respiratory distress syndrome. The positive end-expiratory pressure selected by the different methods were unrelated to each other with the exception of the two methods based on lung mechanics (ExPress and stress index).

CONCLUSIONS: Bedside positive end-expiratory pressure selection methods based on lung mechanics or absolute esophageal pressures provide positive end-expiratory pressure levels unrelated to lung recruitability and similar in mild, moderate, and severe acute respiratory distress syndrome, whereas the oxygenation-based method provided positive end-expiratory pressure levels related with lung recruitability progressively increasing from mild to moderate and severe acute respiratory distress syndrome.

i-STAT® analysis of intraosseous aspirate

March 6, 2014 by  
Filed under All Updates, EMS, ICU, Kids, Resus

Comments Off

In the absence of vascular access we may resort to sending intraosseous aspirates for analysis, but in some laboratories there is concern that the samples can block autoanalysers.

A study on haematology/oncology patients undergoing diagnostic bone marrow aspiration showed clinically acceptable agreement between venous and intraosseous measurements for pH, base excess, sodium, ionised calcium and glucose using an an i-STAT® point-of-care analyser.

Key points are:

  • The first 1-2 ml should be discarded (as in this study)
  • Lactate hasn’t been assessed
  • These patients weren’t critically ill

Analysis of bloodgas, electrolytes and glucose from intraosseous samples using an i-STAT® point-of-care analyser
Resuscitation. 2014 Mar;85(3):359-63


BACKGROUND: Intraosseous access is used in emergency medicine as an alternative when intravenous access is difficult to obtain. Intraosseous samples can be used for laboratory testing to guide treatment. Many laboratories are reluctant to analyse intraosseous samples, as they frequently block conventional laboratory equipment. We aimed to evaluate the feasibility and accuracy of analysis of intraosseous samples using an i-STAT(®) point-of-care analyser.

METHODS: Intravenous and intraosseous samples of twenty children presenting for scheduled diagnostic bone marrow aspiration were analysed using an i-STAT(®) point-of-care analyser. Sample types were compared using Bland Altman plots and by calculating intraclass correlation coefficients and coefficients of variance.

RESULTS: The handheld i-STAT(®)point-of-care analyser proved suitable for analysing intraosseous samples without technical difficulties. Differences between venous and intraosseous samples were clinically acceptable for pH, base excess, sodium, ionised calcium and glucose in these haemodynamically stable patients. The intraclass correlation coefficient was excellent (>0.8) for comparison of intraosseous and intravenous base excess, and moderate (around 0.6) for bicarbonate, sodium and glucose. The coefficient of variance of intraosseous samples was smaller than that of venous samples for most variables.

CONCLUSION: Analysis of intraosseous samples with a bedside, single-use cartridge-based analyser is feasible and avoids the problem of bone marrow contents damaging conventional laboratory equipment. In an emergency situation point-of-care analysis of intraosseous aspirates may be a useful guide to treatment.

Next Page »