Category Archives: PHARM

Prehospital and Retrieval Medicine

All Updates, ICU, Kids, PHARM, Resus, Trauma

Transtracheal airways in kids. Well, pigs' kids anyway

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Ever had to do a surgical airway in a child? Thought not. They’re pretty rare. Bill Heegaard MD from Henepin County Medical Center taught me a few approaches (with the help of an anaesthetised rabbit) which really got me thinking. It’s something I’d often trained for in my internal simulator, and I even keep the equipment for it in my house (listen out for an upcoming podcast on that). Research and experience has demonstrated that open surgical airway techniques are more reliable than transtracheal needle techniques in adults, but what about kids, in whom traditional teaching cautions against open techniques?

Australian investigators who were experienced airway proceduralists evaluated transtracheal needle techniques using a rabbit model (an excellent model for the infant airway). Their success rate was only 60% and they perforated the posterior tracheal wall in 42% of attempts. Of 13 attempts to insert a dedicated paediatric tracheotomy device, the Quicktrach Child, none were successful(1) (they did not use the Quicktrach Infant model as it is not available in Australia).

Danish investigators used fresh piglet cadavers weighing around 8 kg to assess two transtracheal cannulas, in which they achieved success rates of 65.6% and 68.8%(2). There was also a very high rate of posterior tracheal wall perforation. Using an open surgical tracheostomy technique, they were successful in 97% of attempts. These were also experienced operators, with a median anaesthetic experience of 12.5 years.
Their tracheotomy technique was nice and simple, and used just a scalpel, scissors, and surgical towel clips. Here’s their technique:

Simple tracheotomy procedure described by Holm-Knudsen et al

  1. Identify larynx and proximal trachea by palpation
  2. Vertical incision through the skin and subcutaneous tissue from the upper part of larynx to the sternal notch
  3. Grasp strap muscles with two towel forceps and separate in the midline
  4. Palpate and identify the trachea (palpate rather than look for tracheal rings, as in a live patient one would expect bleeding to obscure the view)
  5. Stabilise the trachea by grasping it with a towel forceps
  6. Insert sharp tip of the scissors between two tracheal rings and lift the trachea anteriorly to avoid damage to the posterior wall
  7. Cut vertically in the midline of the trachea with the scissors – they chose to use the scissors to cut the tracheal rings to facilitate tube insertion
  8. Insert the tracheal tube

Using ultrasound and CT to evaluate comparative airway dimensions, the authors concluded that the pig model is most useful for training emergency airway management in older children aged 5–10 years.
Why were they doing a tracheotomy rather than a cricothyroidotomy? Reasons given by the authors include:

  • The infant cricothyroid membrane is very small
  • Palpation of the thyroid notch may be hindered by the overlying hyoid bone
  • The mandible may obstruct needle access to the cricothyroid membrane given the cephalad position in the neck of the infant larynx.

From an emergency medicine point of view, there are a couple of other reasons why we need to be able to access the trachea lower than the cricothyroid membrane. One is fractured larynx or other blunt or penetrating airway injury where there may be anatomical disruption at the cricothyroid level. The other situation is foreign body airway obstruction, when objects may lodge at the level of the cricoid ring which is functionally the narrowest part of the pediatric upper airway. Of course, alternative methods might be considered to remove the foreign body prior to tracheotomy, such as employing basic choking algorithms, and other techniques depending on whether you do or don’t have equipment.

Take home messages

  • Transtracheal airways in kids are so rare, we can’t avoid extrapolating animal data
  • Whichever infant or paediatric model is used, transtracheal needle techniques have a high rate of failure even by ‘experienced’ operators
  • The small size and easy compressibility of the airway probably contributes to this failure rate, including the high rate of posterior wall puncture
  • In keeping with adult audit data, open surgical techniques may have a higher success rate
  • Tracheotomy may be necessary rather than cricothyroidotomy in infants and children depending on clinical scenario and accessibility of anatomy
  • The stress and blood that is not simulated in cadaveric animal models will make open tracheotomy harder in a live patient, and so these success rates may not translate. However these factors do mean that whatever technique is used must be kept simple and should employ readily available and familiar equipment
  • Something to maintain control and anterior position of the anterior trachea wall should be used during incision and intubation of the trachea. The study reported here used towel clips; sutures around the tracheal rings may also be used (see image below)

I recommend you add ‘paediatric tracheotomy’ to the list of procedures you might need to do (if it’s not already there). Identify what equipment you would use and run the simulation in your head and in your work environment.
Have fun.

1. The ‘Can’t Intubate Can’t Oxygenate’ scenario in Pediatric Anesthesia: a comparison of different devices for needle cricothyroidotomy
Paediatr Anaesth. 2012 Dec;22(12):1155-8

BACKGROUND: Little evidence exists to guide the management of the ‘Can’t Intubate, Can’t Oxygenate’ (CICO) scenario in pediatric anesthesia.

OBJECTIVES: To compare two intravenous cannulae for ease of use, success rate and complication rate in needle tracheotomy in a postmortem animal model of the infant airway, and trial a commercially available device using the same model.

METHODS: Two experienced proceduralists repeatedly attempted cannula tracheotomy in five postmortem rabbits, alternately using 18-gauge (18G) and 14-gauge (14G) BD Insyte(™) cannulae (BD, Franklin Lakes, NJ, USA). Attempts began at the first tracheal cartilage, with subsequent attempts progressively more caudad. Success was defined as intratracheal cannula placement. In each rabbit, an attempt was then made by each proceduralist to perform a cannula tracheotomy using the Quicktrach Child(™) device (VBM Medizintechnik GmbH, Sulz am Neckar, Germany).

RESULTS: The rabbit tracheas were of similar dimensions to a human infant. 60 attempts were made at cannula tracheotomy, yielding a 60% success rate. There was no significant difference in success rate, ease of use, or complication rate between cannulae of different gauge. Successful aspiration was highly predictive (positive predictive value 97%) and both sensitive (89%) and specific (96%) for tracheal cannulation. The posterior tracheal wall was perforated in 42% of tracheal punctures. None of 13 attempts using the Quicktrach Child(™) were successful.

CONCLUSION: Cannula tracheotomy in a model comparable to the infant airway is difficult and not without complication. Cannulae of 14- and 18-gauge appear to offer similar performance. Successful aspiration is the key predictor of appropriate cannula placement. The Quicktrach Child was not used successfully in this model. Further work is required to compare possible management strategies for the CICO scenario

2. Emergency airway access in children – transtracheal cannulas and tracheotomy assessed in a porcine model
Paediatr Anaesth. 2012 Dec;22(12):1159-65

OBJECTIVES: In the rare scenario when it is impossible to oxygenate or intubate a child, no evidence exists on what strategy to follow.

AIM: The aim of this study was to compare the time and success rate when using two different transtracheal needle techniques and also to measure the success rate and time when performing an emergency tracheotomy in a piglet cadaver model.

METHODS: In this randomized cross-over study, we included 32 anesthesiologists who each inserted two transtracheal cannulas (TTC) using a jet ventilation catheter and an intravenous catheter in a piglet model. Second, they performed an emergency tracheotomy. A maximum of 2 and 4 min were allowed for the procedures, respectively. The TTC procedures were recorded using a video scope.

RESULTS: Placement of a transtracheal cannula was successful in 65.6% and 68.8% of the attempts (P = 0.76), and the median duration of the attempts was 69 and 42 s (P = 0.32), using the jet ventilation catheter and the intravenous catheter, respectively. Complications were frequent in both groups, especially perforation of the posterior tracheal wall. Performing an emergency tracheotomy was successful in 97%, in a median of 88 s.

CONCLUSIONS: In a piglet model, we found no significant difference in success rates or time to insert a jet ventilation cannula or an intravenous catheter transtracheally, but the incidence of complications was high. In the same model, we found a 97% success rate for performing an emergency tracheotomy within 4 min with a low rate of complications.

Acute Med, All Updates, ICU, Kids, PHARM, Resus, Ultrasound

Externally rotate leg for femoral vein access

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Want to access the femoral vein? Externally rotate the leg at the hip and things might be a bit easier. This study was done in adult patients, with the knee straight and no abduction applied. External rotation is also helpful in kids, with abduction up to sixty degrees.


Objective: To determine if external rotation of the leg increases the size and accessibility of the femoral vein compared with a neutral position.

Methods: One hundred patients presenting to a tertiary teaching hospital were prospectively recruited. The right common femoral vein of each subject was scanned with a linear probe (5–10 MHz) inferior to the inguinal ligament, with the leg in a neutral position and then in the externally rotated position. The transverse diameter of the femoral vein, the accessible diameter of the vein (lying medial to the femoral artery) and the depth of the vein were measured.

Results: The mean diameter of the femoral vein in the externally rotated leg was greater than with the leg in the neutral position (15.4 mm vs 13.8 mm); the mean difference was 1.6 mm (95% CI 1.3–1.9). The mean accessible diameter of the femoral vein was larger with the leg externally rotated (13.8 mm vs 11.7 mm, mean difference 2.1 mm, 95% CI 1.8–2.5). The depth from the skin to the femoral vein was less with the leg in external rotation (20.9 mm vs 22.6 mm, mean difference 1.7 mm, 95% CI 1.2–2.2). The mean diameter and depth were greater in patients with overweight or obese body mass index (BMI) measurements in both leg positions. The increase in femoral vein diameter and accessibility with external rotation was observed in all BMI groups.

Conclusion: The total and accessible femoral vein diameter is increased and the surface depth of the vein is decreased by placing the leg in external rotation compared with the neutral position.

Simple external rotation of the leg increases the size and accessibility of the femoral vein
Emerg Med Australas. 2012 Aug;24(4):408-13

All Updates, ICU, PHARM, Resus, Ultrasound

Echo for cardiac arrest outcome prediction

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A meta-analysis of studies evaluation transthoracic echo as a means of predicting return of spontaneous circulation in cardiac arrest (ROSC) provides some likelihood ratios to what we already know: absence of sonographic cardiac activity means a very low chance of ROSC.

The authors report a pooled negative LR of 0.18 (95% CI = 0.10 to 0.31), and a positive likelihood ratio of 4.26 (95% CI = 2.63 to 6.92).

They conclude that focused transthoracic echo is a fairly effective (although not definitive) test for predicting death if no cardiac activity is noted during resuscitation, and recommend interpreting the echo in the light of the test characteristics and the clinical pre-test probability, as one should do for all imaging investigations:


“An elderly patient with an unwitnessed cardiac arrest already has very poor odds for survival. Confirmation of asystole on echo lowers those pretest odds by a factor of 5.6 and therefore might lead to termination of resuscitation. However, in the case of a 50-year-old rescued from drowning, detection of cardiac contractility on echo would increase his already fair odds of survival by a factor of 4.3, prompting continued aggressive resuscitation.”

Only five relatively small studies contributed to the findings. A more definitive answer to this question should be provided in the future by the multi-centre REASON 1 trial.

Objectives:  The objective was to determine if focused transthoracic echocardiography (echo) can be used during resuscitation to predict the outcome of cardiac arrest.

Methods:  A literature search of diagnostic accuracy studies was conducted using MEDLINE via PubMed, EMBASE, CINAHL, and Cochrane Library databases. A hand search of references was performed and experts in the field were contacted. Studies were included for further appraisal and analysis only if the selection criteria and reference standards were met. The eligible studies were appraised and scored by two independent reviewers using a modified quality assessment tool for diagnostic accuracy studies (QUADAS) to select the papers included in the meta-analysis.

Results:  The initial search returned 2,538 unique papers, 11 of which were determined to be relevant after screening criteria were applied by two independent researchers. One additional study was identified after the initial search, totaling 12 studies to be included in our final analysis. The total number of patients in these studies was 568, all of whom had echo during resuscitation efforts to determine the presence or absence of kinetic cardiac activity and were followed up to determine return of spontaneous circulation (ROSC). Meta-analysis of the data showed that as a predictor of ROSC during cardiac arrest, echo had a pooled sensitivity of 91.6% (95% confidence interval [CI] = 84.6% to 96.1%), and specificity was 80.0% (95% CI = 76.1% to 83.6%). The positive likelihood ratio for ROSC was 4.26 (95% CI = 2.63 to 6.92), and negative likelihood ratio was 0.18 (95% CI = 0.10 to 0.31). Heterogeneity of the results (sensitivity) was nonsignificant (Cochran’s Q: χ(2) = 10.63, p = 0.16, and I(2) = 34.1%).

Conclusions:  Echocardiography performed during cardiac arrest that demonstrates an absence of cardiac activity harbors a significantly lower (but not zero) likelihood that a patient will experience ROSC. In selected patients with a higher likelihood of survival from cardiac arrest at presentation, based on established predictors of survival, echo should not be the sole basis for the decision to cease resuscitative efforts. Echo should continue to be used only as an adjunct to clinical assessment in predicting the outcome of resuscitation for cardiac arrest.

Bedside Focused Echocardiography as Predictor of Survival in Cardiac Arrest Patients: A Systematic Review
Acad Emerg Med. 2012 Oct;19(10):1119-1126

All Updates, ICU, PHARM, Resus

Aeromedical retrieval: invasive vs noninvasive blood pressure

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The chaps from the Emergency Medical Retrieval Service in the UK compared invasive (IABP) and non-invasive blood pressure (NIBP) measurements on the ground and in the air. They concluded that NIBP was unreliable, although it was no worse in the aeromedical environment than in the hospital. Not surprisingly there was a better correlation between the mean IABP and NIBP than systolic or diastolic pressures (oscillometric NIBP devices measure the mean BP and derive systolic and diastolic using an algorithm specific to the device).
In their summary, they recommend:

  • IABP monitoring should be used in any unwell patient in whom accurate blood pressure measurement is desirable.
  • The aeromedical transport environment does not lead to less precise NIBP results than the non-transport environment.
  • Where NIBP measurement is the only option, the mean blood pressure should be used in preference to systolic measurements


Blood pressure measurement is an essential physiological measurement for all critically ill patients. Previous work has shown that non-invasive blood pressure is not an accurate reflection of invasive blood pressure measurement. In a transport environment, the effects of motion and vibration may make non-invasive blood pressure less accurate.

Consecutive critically ill patients transported by a dedicated aeromedical retrieval and critical care transfer service with simultaneous invasive and non-invasive blood pressure measurements were analysed. Two sets of measurements were recorded, first in a hospital environment before departure (pre-flight) and a second during aeromedical transport (in-flight).

A total of 56 complete sets of data were analysed. Bland-Altman plots showed limits of agreement (precision) for pre-flight systolic blood pressure were -37.3 mmHg to 30.0 mmHg, and for pre-flight mean arterial pressure -20.5 mmHg to 25.0 mmHg. The limits of agreement for in-flight systolic blood pressure were -40.6 mmHg to 33.1 mmHg, while those for in-flight mean blood pressure in-flight were -23.6 mmHg to 24.6 mmHg. The bias for the four conditions ranged from 0.5 to -3.8 mmHg. There were no significant differences in values between pre-flight and in-flight blood pressure measurements for all categories of blood pressure measurement.

Thus, our data show that non-invasive blood pressure is not a precise reflection of invasive intra-arterial blood pressure. Mean blood pressure measured non-invasively may be a better marker of invasive blood pressure than systolic blood pressure. Our data show no evidence of non-invasive blood pressures being less accurate in an aeromedical transport environment.

Comparison of non-invasive and invasive blood pressure in aeromedical care
Anaesthesia. 2012 Dec;67(12):1343-7

All Updates, Guidelines, ICU, PHARM, Resus, Trauma

A whole bunch of trauma guidelines

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The Eastern Association for the Surgery of Trauma has published a number of helpful evidence-based guidelines for trauma management, and many of them are included in this month’s Journal of Trauma and Acute Care Surgery
Here are brief snippets from some of them. All the guidelines can be viewed or downloaded in full for free here.
 
Nonoperative management of blunt hepatic injury

  • Nonoperative management of blunt hepatic injuries currently is the treatment modality of choice in hemodynamically stable patients, irrespective of the grade of injury or patient age.
  • Patients presenting with hemodynamic instability and peritonitis still warrant emergent operative intervention.
  • Intravenous contrast enhanced computed tomographic scan is the diagnostic modality of choice for evaluating blunt hepatic injuries.

 
Selective nonoperative management of blunt splenic injury

  • Nonoperative management of blunt splenic injuries is now the treatment modality of choice in hemodynamically stable patients, irrespective of the grade of injury, patient age, or the presence of associated injuries.
  • Patients presenting with hemodynamic instability and peritonitis still warrant emergent operative intervention.
  • Intravenous contrast enhanced computed tomographic scan is the diagnostic modality of choice for evaluating blunt splenic injuries.

 
Screening for blunt cardiac injury

  • Electrocardiogram (ECG) alone is not sufficient to rule out BCI.
  • BCI can be ruled out only if both ECG result and troponin I level are normal, a significant change from the previous guideline.
  • Patients with new ECG changes and/or elevated troponin I should be admitted for monitoring.
  • Echocardiogram is not beneficial as a screening tool for BCI and should be reserved for patients with hypotension and/or arrhythmias.
  • The presence of a sternal fracture alone does not predict BCI.
  • Cardiac computed tomography or magnetic resonance imaging can be used to differentiate acute myocardial infarction from BCI in trauma patients.

 
Evaluation and management of penetrating lower extremity arterial trauma

  • Expedited triage of patients is possible with physical examination and/or the measurement of ankle-brachial indices.
  • Computed tomographic angiography has become the diagnostic study of choice when imaging is required.
  • Tourniquets and intravascular shunts have emerged as adjuncts in the treatment of penetrating lower extremity arterial trauma.

 
Prophylactic antibiotic use in penetrating abdominal trauma

  • There is evidence to support a Level I recommendation that prophylactic antibiotics should only be administered for 24 hours in the presence of a hollow viscus injury.
  • There are no data to support continuing prophylactic antibiotics longer than 24 hours in damage control laparotomy.

 
Screening for thoracolumbar spinal injuries in blunt trauma

  • Multidetector computed tomographic scans have become the screening modality of choice and the criterion standard in screening for TLS injuries.
  • Patients without altered mentation or significant mechanism may be excluded by clinical examination without imaging.
  • Patients with gross neurologic deficits or concerning clinical examination findings with negative imaging should receive a magnetic resonance imaging expediently, and the spine service should be consulted

 
Emergency tracheal intubation immediately following traumatic injury

  • The decision to intubate a patient following traumatic injury is based on multiple factors, including the need for oxygenation and ventilation, the extent and mechanism of injury, predicted operative need, or progression of disease.
  • Rapid sequence intubation with direct laryngoscopy continues to be the recommended method for ETI, although the use of airway adjuncts such as blind insertion supraglottic devices and video laryngoscopy may be useful in facilitating successful ETI and may be preferred in certain patient populations.
  • There is no pharmacologic induction agent of choice for ETI; however, succinylcholine is the neuromuscular blockade agent recommended for rapid sequence intubation.

 
Presumptive antibiotic use in tube thoracostomy for traumatic hemopneumothorax

  • Routine presumptive antibiotic use to reduce the incidence of empyema and pneumonia in TT for traumatic hemopneumothorax is controversial; however, there is insufficient published evidence to support any recommendation either for or against this practice.

 
Evaluation and management of geriatric trauma

  • Effective evidence-based care of aging patients necessitates aggressive triage, correction of coagulopathy, and limitation of care when clinical evidence points toward an overwhelming likelihood of poor long-term prognosis

 
Management of pulmonary contusion and flail chest

  • Patients with PC-FC should not be excessively fluid restricted but should be resuscitated to maintain signs of adequate tissue perfusion.
  • Obligatory mechanical ventilation in the absence of respiratory failure should be avoided.
  • The use of optimal analgesia and aggressive chest physiotherapy should be applied to minimize the likelihood of respiratory failure.
  • Epidural catheter is the preferred mode of analgesia delivery in severe flail chest injury.
  • Paravertebral analgesia may be equivalent to epidural analgesia and may be appropriate in certain situations when epidural is contraindicated.
  • A trial of mask continuous positive airway pressure should be considered in alert patients with marginal respiratory status.
  • Patients requiring mechanical ventilation should be supported in a manner based on institutional and physician preference and separated from the ventilator at the earliest possible time.
  • Positive end-expiratory pressure or continuous positive airway pressure should be provided.
  • High-frequency oscillatory ventilation should be considered for patients failing conventional ventilatory modes. Independent lung ventilation may also be considered in severe unilateral pulmonary contusion when shunt cannot be otherwise corrected.
  • Surgical fixation of flail chest may be considered in cases of severe flail chest failing to wean from the ventilator or when thoracotomy is required for other reasons.
  • Self-activating multidisciplinary protocols for the treatment of chest wall injuries may improve outcome and should be considered where feasible.
  • Steroids should not be used in the therapy of pulmonary contusion.
  • Diuretics may be used in the setting of hydrostatic fluid overload in hemodynamically stable patients or in the setting of known concurrent congestive heart failure.

 
Evaluation and management of small-bowel obstruction

  • Level I evidence now exists to recommend the use of computed tomographic scan, especially multidetector computed tomography with multiplanar reconstructions, in the evaluation of patients with SBO because it can provide incremental clinically relevant information over plains films that may lead to changes in management.
  • Patients with evidence of generalized peritonitis, other evidence of clinical deterioration, such as fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain, or patients with evidence of ischemia on imaging should undergo timely exploration.
  • The remainder of patients can safely undergo initial nonoperative management for both partial and complete SBO.
  • Water-soluble contrast studies should be considered in patients who do not clinically resolve after 48 to 72 hours for both diagnostic and potential therapeutic purposes.
  • Laparoscopic treatment of SBO has been demonstrated to be a viable alternative to laparotomy in selected cases.

 
2012 Eastern Association for the Surgery of Trauma (EAST) Practice Management Guidelines Supplement
J Trauma Acute Care Surg. 2012 Nov;73(5 Suppl 4)

All Updates, PHARM, Trauma

Prehospital ketamine analgesia

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A prospective open-label randomised controlled trial in prehospital patients receiving morphine for traumatic pain compared intravenous ketamine with additional morphine.
Analgesia was superior in the ketamine group, with some minor (expected) adverse effects.
This small study adds to the prehospital ketamine literature and provides some support to ambulance services considering introducing ketamine analgesia.


Study objective: We assess the efficacy of intravenous ketamine compared with intravenous morphine in reducing pain in adults with significant out-of-hospital traumatic pain.

Methods: This study was an out-of-hospital, prospective, randomized, controlled, open-label study. Patients with trauma and a verbal pain score of greater than 5 after 5 mg intravenous morphine were eligible for enrollment.
Patients allocated to the ketamine group received a bolus of 10 or 20 mg, followed by 10 mg every 3 minutes thereafter. Patients allocated to the morphine alone group received 5 mg intravenously every 5 minutes until pain free. Pain scores were measured at baseline and at hospital arrival.

Results: A total of 135 patients were enrolled between December 2007 and July 2010. There were no differences between the groups at baseline. After the initial 5-mg dose of intravenous morphine, patients allocated to ketamine received a mean of 40.6 mg (SD 25 mg) of ketamine. Patients allocated to morphine alone received a mean of 14.4 mg (SD 9.4 mg) of morphine. The mean pain score change was 5.6 (95% confidence interval [CI] 6.2 to 5.0) in the ketamine group compared with 3.2 (95% CI 3.7 to 2.7) in the morphine group. The difference in mean pain score change was 2.4 (95% CI 3.2 to 1.6) points. The intravenous morphine group had 9 of 65 (14%; 95% CI 6% to 25%) adverse effects reported (most commonly nausea [6/65; 9%]) compared with 27 of 70 (39%; 95% CI 27% to 51%) in the ketamine group (most commonly disorientation [8/70; 11%]).

Conclusion: Intravenous morphine plus ketamine for out-of-hospital adult trauma patients provides analgesia superior to that of intravenous morphine alone but was associated with an increase in the rate of minor adverse effects.

Morphine and Ketamine Is Superior to Morphine Alone for Out-of-Hospital Trauma Analgesia: A Randomized Controlled Trial
Ann Emerg Med. 2012 Jun;59(6):497-503

All Updates, ICU, PHARM, Resus, Trauma

Needle decompression: it's still not going to work

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A pet topic that keeps coming up here is management of tension pneumothorax. Plenty of studies demonstrate that traditionally taught needle thoracostomy may fail, and open, or ‘finger’ thoracostomy is recommended for the emergency management of tension pneumothorax in a patient who is being ventilated with positive pressure (including those patients in cardiac arrest).
A recent CT scan-based study of adult trauma patients makes the case that needle decompression with a standard iv cannula would be expected to fail in 42.5% of cases at the second intercostal space (ICS) compared with 16.7% at the fifth ICS at the anterior axillary line (AAL).
The authors add an important point: “As BMI increases, there is a stepwise increase in chest wall thickness, further compounding the difficulty of needle placement in all but the lowest BMI quartile for the second ICS.”
An accompanying editorial cautions that the proximity of the heart may confer a safety issue if a needle is inserted blindly into the left 5th ICS at the AAL.


Objective To compare the distance to be traversed during needle thoracostomy decompression performed at the second intercostal space (ICS) in the midclavicular line (MCL) with the fifth ICS in the anterior axillary line (AAL).

Design Patients were separated into body mass index (BMI) quartiles, with BMI calculated as weight in kilograms divided by height in meters squared. From each BMI quartile, 30 patients were randomly chosen for inclusion in the study on the basis of a priori power analysis (n = 120). Chest wall thickness on computed tomography at the second ICS in the MCL was compared with the fifth ICS in the AAL on both the right and left sides through all BMI quartiles.

Setting Level I trauma center.

Patients Injured patients aged 16 years or older evaluated from January 1, 2009, to January 1, 2010, undergoing computed tomography of the chest.

Results A total of 680 patients met the study inclusion criteria (81.5% were male and mean age was 41 years [range, 16-97 years]). Of the injuries sustained, 13.2% were penetrating, mean (SD) Injury Severity Score was 15.5 (10.3), and mean BMI was 27.9 (5.9) (range, 15.4-60.7). The mean difference in chest wall thickness between the second ICS at the MCL and the fifth ICS at the AAL was 12.9 mm (95% CI, 11.0-14.8; P < .001) on the right and 13.4 mm (95% CI, 11.4-15.3; P < .001) on the left. There was a stepwise increase in chest wall thickness across all BMI quartiles at each location of measurement. There was a significant difference in chest wall thickness between the second ICS at the MCL and the fifth ICS at the AAL in all quartiles on both the right and the left. The percentage of patients with chest wall thickness greater than the standard 5-cm decompression needle was 42.5% at the second ICS in the MCL and only 16.7% at the fifth ICS in the AAL.

Conclusions In this computed tomography–based analysis of chest wall thickness, needle thoracostomy decompression would be expected to fail in 42.5% of cases at the second ICS in the MCL compared with 16.7% at the fifth ICS in the AAL. The chest wall thickness at the fifth ICS AAL was 1.3 cm thinner on average and may be a preferred location for needle thoracostomy decompression.

Radiologic evaluation of alternative sites for needle decompression of tension pneumothorax
Arch Surg. 2012 Sep 1;147(9):813-8

All Updates, ICU, Kids, PHARM, Resus

Don't bronchodilators work in infants?

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Inpatient paediatric teams can be scornful when bronchodilators are given by ED staff to wheezing infants, correctly referring to the lack of evidence of clinical benefit(1). There is however a persisting meme out there I’ve heard on a number of occasions that ‘young infants don’t have the receptors so inhaled beta agonists will never work.’ I’d love to know where this comes from.
Apparently, beta 2-receptors are present from the 16th gestational week(2). Pulmonary function testing of ventilated, very-low-birth-weight babies has shown that some consistently responded to beta-agonists whereas others did not(3). A newly published study reports that a quarter of mechanically ventilated infants with bronchiolitis were responders to inhaled albuterol, defined as a reduction in respiratory system resistance more than 30% below baseline(4).
In summary: beta-agonist bronchodilators have not been shown to improve clinical outcomes in wheezing infants. However some infants with some wheezing disorders will show a response in terms of pulmonary function. The receptors are there, and in life-threatening presentations bronchodilators should certainly be considered.
1. Short acting beta agonists for recurrent wheeze in children under 2 years of age
Cochrane Database Syst Rev. 2002;(3):CD002873
[EXPAND Click to read abstract]


BACKGROUND: Wheeze is a common symptom in infancy and is a common cause for both primary care consultations and hospital admission. Beta2-adrenoceptor agonists (b2-agonists) are the most frequently used as bronchodilator but their efficacy is questionable.
OBJECTIVES: To determine the effectiveness of b2-agonist for the treatment of infants with recurrent and persistent wheeze.
SEARCH STRATEGY: Relevant trials were identified using the Cochrane Airways Group database (CENTRAL), Medline and Pubmed. The database search used the following terms: Wheeze or asthma and Infant or Child and Short acting beta-agonist or Salbutamol (variants), Albuterol, Terbutaline (variants), Orciprenaline, Fenoterol

SELECTION CRITERIA: Randomised controlled trials comparing the effect of b2-agonist against placebo in children under 2 years of age who had had two or more previous episodes of wheeze, not related to another form of chronic lung disease.
DATA COLLECTION AND ANALYSIS: Eight studies met the criteria for inclusion in this meta-analysis. The studies investigated patients in three settings: at home (3 studies), in hospital (2 studies) and in the pulmonary function laboratory (3 studies). The main outcome measure was change in respiratory rate except for community based studies where symptom scores were used.

MAIN RESULTS: The studies were markedly heterogeneous and between study comparisons were limited. Improvement in respiratory rate, symptom score and oxygen saturation were noted in one study in the emergency department following two salbutamol nebulisers but this had no impact on hospital admission. There was a reduction in bronchial reactivity following salbutamol. There was no significant benefit from taking regular inhaled salbutamol on symptom scores recorded at home.

REVIEWER’S CONCLUSIONS: There is no clear benefit of using b2-agonists in the management of recurrent wheeze in the first two years of life although there is conflicting evidence. At present, further studies should only be performed if the patient group can be clearly defined and there is a suitable outcome parameter capable of measuring a response.

[/EXPAND]
2. The beta-2-agonists in asthma in infants and young children
Arch Pediatr. 2002 Aug;9 Suppl 3:384s-389s
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Beta 2-agonists, by inducing a fast and long relaxation of the bronchial smooth muscle, are considered as the more potent bronchodilators. beta 2-receptors are present from the 16th gestational week, explaining a possible bronchial response in the youngest children. beta 2-agonists do not induce any bronchodilator response in healthy children. Short-acting beta 2-agonists (salbutamol or albuterol, terbutaline) are indicated for asthma attacks, as needed in chronic asthma, and for prevention of symptoms during effort. They are safe and secure. The more efficient route of administration in preschool children is pressurized metered-dose inhaler used with a spacer device. Therefore, whatever the route of inhalation chosen (inhalation, injection, or continuous nebulization in acute asthma attack), more specified indications and doses are needed in young children. Long-acting beta 2-agonists (formoterol, salmeterol) are not authorized in France in children under 4 to 5 years of age depending on the drug used. Because of new oral formulations and recent considerations about their use in asthma attack, instead of short-acting beta 2-agonists, their indication in preschool asthmatic children might be reconsidered.

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3. Use of a beta-agonist in ventilated, very-low-birth-weight babies: a longitudinal evaluation
Dev Pharmacol Ther. 1990;15(2):61-7
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To determine if there is a specific postnatal (PNA) or postconceptional age (PCA) at which ventilated preterm infants respond to beta-agonists, we evaluated 15 infants with a mean gestational age of 26.5 +/- 1.5 weeks and mean birth weight of 0.89 +/- 0.23 kg who required mechanical ventilation at 10 days of age. Weekly pulmonary function testing (PFT) was performed before and 1 h after administration of albuterol. Taking the group as a whole, as well as individual babies, regression analysis showed no relationship between positive response and either PNA or PCA. Evaluation of individual infants, however, showed that some consistently responded to beta-agonists whereas others did not. We recommend individual PFT to identify those infants who will benefit from use of beta-agonists.

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4. Pulmonary mechanics following albuterol therapy in mechanically ventilated infants with bronchiolitis
J Asthma. 2012 Sep;49(7):688-96
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BACKGROUND AND AIMS: Bronchiolitis is a common cause of critical illness in infants. Inhaled β(2)-agonist bronchodilators are frequently used as part of treatment, despite unproven effectiveness. The purpose of this study was to describe the physiologic response to these medications in infants intubated and mechanically ventilated for bronchiolitis.

MATERIALS AND METHODS: We conducted a prospective trial of albuterol treatment in infants intubated and mechanically ventilated for bronchiolitis. Before and for 30 minutes following inhaled albuterol treatment, sequential assessments of pulmonary mechanics were determined using the interrupter technique on repeated consecutive breaths.

RESULTS: Fifty-four infants were enrolled. The median age was 44 days (25-75%; interquartile range (IQR) 29-74 days), mean hospital length of stay (LOS) was 18.3 ± 13.3 days, mean ICU LOS was 11.3 ± 6.4 days, and mean duration of mechanical ventilation was 8.5 ± 3.5 days. Fifty percent (n = 27) of the infants were male, 81% (n = 44) had public insurance, 80% (n = 41) were Caucasian, and 39% (n = 21) were Hispanic. Fourteen of the 54 (26%) had reduction in respiratory system resistance (Rrs) that was more than 30% below baseline, and were defined as responders to albuterol. Response to albuterol was not associated with demographic factors or hospitalization outcomes such as LOS or duration of mechanical ventilation. However, increased Rrs, prematurity, and non-Hispanic ethnicity were associated with increased LOS.

CONCLUSIONS: In this population of mechanically ventilated infants with bronchiolitis, relatively few had a reduction in pulmonary resistance in response to inhaled albuterol therapy. This response was not associated with improvements in outcomes.

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Acute Med, All Updates, ICU, PHARM, Resus

What's with all the chloride? An assault on salt

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I continue to be bewildered at my ED colleagues’ overwhelming preference for 0.9% saline as a resuscitation fluid regardless of clinical presentation. However, I have to acknowledge a lack of robust high level clinical evidence demonstrating its relative harm compared with more balanced solutions such as Hartmann’s / Ringer’s lactate or one of the more scarcely available Plasma-Lyte solutions.
Human and animal studies have demonstrated that saline exacerbates hyperchloraemia and metabolic acidosis and has renal effects including renal vasoconstriction and decreased glomerular filtration rate. A large observational study on surgical patients suggested that saline therapy increases the risk of patients requiring acute dialysis compared with Plasma-Lyte administration(1).
A new study in JAMA provides some further clinical evidence that saline has harmful renal effects(2). It was a before-and-after observational study, in which the change was a restriction in chloride-rich fluids so that they were made available only after prescription by the attending specialist for specific conditions (eg, hyponatraemia, traumatic brain injury, and cerebral oedema). Four of the authors published another study on the metabolic effects of this changed fluid strategy, presumably on the same or an overlapping cohort of patients, which I blogged about here.
Significant findings were that the chloride-restrictive strategy was associated with a significantly lower increase in serum creatinine level during ICU stay, a decrease in the incidence of renal injury and failure (according to the RIFLE definitions), and a decrease in renal replacement therapy. These effects persisted after adjusting for known contributors to acute kidney injury.
As this is not a randomised trial cause and effect cannot be assumed, but this is consistent with other work.
In summary, keep pushing the saline if you want to increase your patients’ risk of acute kidney injury and the need for dialysis, whilst rendering them acidotic. You may even decrease their gut perfusion(3) and give them abdominal discomfort and subjective decreased cognitive ability(4). Alternatively, give Hartmann’s / Ringer’s lactate… although bear in mind that might not be such a good choice in the context of hyponatraemia, alkalaemia, cerebral oedema, or traumatic brain injury.
1. Major complications, mortality, and resource utilization after open abdominal surgery: 0.9% saline compared to Plasma-Lyte
Ann Surg. 2012 May;255(5):821-9
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OBJECTIVE: To assess the association of 0.9% saline use versus a calcium-free physiologically balanced crystalloid solution with major morbidity and clinical resource use after abdominal surgery.

BACKGROUND: 0.9% saline, which results in a hyperchloremic acidosis after infusion, is frequently used to replace volume losses after major surgery.

METHODS: An observational study using the Premier Perspective Comparative Database was performed to evaluate adult patients undergoing major open abdominal surgery who received either 0.9% saline (30,994 patients) or a balanced crystalloid solution (926 patients) on the day of surgery. The primary outcome was major morbidity and secondary outcomes included minor complications and acidosis-related interventions. Outcomes were evaluated using multivariable logistic regression and propensity scoring models.

RESULTS: For the entire cohort, the in-hospital mortality was 5.6% in the saline group and 2.9% in the balanced group (P < 0.001). One or more major complications occurred in 33.7% of the saline group and 23% of the balanced group (P < 0.001). In the 3:1 propensity-matched sample, treatment with balanced fluid was associated with fewer complications (odds ratio 0.79; 95% confidence interval 0.66-0.97). Postoperative infection (P = 0.006), renal failure requiring dialysis (P < 0.001), blood transfusion (P < 0.001), electrolyte disturbance (P = 0.046), acidosis investigation (P < 0.001), and intervention (P = 0.02) were all more frequent in patients receiving 0.9% saline.

CONCLUSIONS: Among hospitals in the Premier Perspective Database, the use of a calcium-free balanced crystalloid for replacement of fluid losses on the day of major surgery was associated with less postoperative morbidity than 0.9% saline.

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2. Association Between a Chloride-Liberal vs Chloride-Restrictive Intravenous Fluid Administration Strategy and Kidney Injury in Critically Ill Adults
JAMA. 2012 Oct 17;308(15):1566-72
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CONTEXT: Administration of traditional chloride-liberal intravenous fluids may precipitate acute kidney injury (AKI).

OBJECTIVE: To assess the association of a chloride-restrictive (vs chloride-liberal) intravenous fluid strategy with AKI in critically ill patients.

DESIGN, SETTING, AND PATIENTS: Prospective, open-label, sequential period pilot study of 760 patients admitted consecutively to the intensive care unit (ICU) during the control period (February 18 to August 17, 2008) compared with 773 patients admitted consecutively during the intervention period (February 18 to August 17, 2009) at a university-affiliated hospital in Melbourne, Australia.

INTERVENTIONS: During the control period, patients received standard intravenous fluids. After a 6-month phase-out period (August 18, 2008, to February 17, 2009), any use of chloride-rich intravenous fluids (0.9% saline, 4% succinylated gelatin solution, or 4% albumin solution) was restricted to attending specialist approval only during the intervention period; patients instead received a lactated solution (Hartmann solution), a balanced solution (Plasma-Lyte 148), and chloride-poor 20% albumin.

MAIN OUTCOME MEASURES: The primary outcomes included increase from baseline to peak creatinine level in the ICU and incidence of AKI according to the risk, injury, failure, loss, end-stage (RIFLE) classification. Secondary post hoc analysis outcomes included the need for renal replacement therapy (RRT), length of stay in ICU and hospital, and survival.

RESULTS Chloride administration decreased by 144 504 mmol (from 694 to 496 mmol/patient) from the control period to the intervention period. Comparing the control period with the intervention period, the mean serum creatinine level increase while in the ICU was 22.6 μmol/L (95% CI, 17.5-27.7 μmol/L) vs 14.8 μmol/L (95% CI, 9.8-19.9 μmol/L) (P = .03), the incidence of injury and failure class of RIFLE-defined AKI was 14% (95% CI, 11%-16%; n = 105) vs 8.4% (95% CI, 6.4%-10%; n = 65) (P < .001), and the use of RRT was 10% (95% CI, 8.1%-12%; n = 78) vs 6.3% (95% CI, 4.6%-8.1%; n = 49) (P = .005). After adjustment for covariates, this association remained for incidence of injury and failure class of RIFLE-defined AKI (odds ratio, 0.52 [95% CI, 0.37-0.75]; P < .001) and use of RRT (odds ratio, 0.52 [95% CI, 0.33-0.81]; P = .004). There were no differences in hospital mortality, hospital or ICU length of stay, or need for RRT after hospital discharge.
CONCLUSION The implementation of a chloride-restrictive strategy in a tertiary ICU was associated with a significant decrease in the incidence of AKI and use of RRT.

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3. The effects of balanced versus saline-based hetastarch and crystalloid solutions on acid-base and electrolyte status and gastric mucosal perfusion in elderly surgical patients
Anesth Analg. 2001 Oct;93(4):811-6
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The IV administration of sodium chloride solutions may produce a metabolic acidosis and gastrointestinal dysfunction. We designed this trial to determine whether, in elderly surgical patients, crystalloid and colloid solutions with a more physiologically balanced electrolyte formulation, such as Hartmann’s solution and Hextend, can provide a superior metabolic environment and improved indices of organ perfusion when compared with saline-based fluids. Forty-seven elderly patients undergoing major surgery were randomly allocated to one of two study groups. Patients in the Balanced Fluid group received an intraoperative fluid regimen that consisted of Hartmann’s solution and 6% hetastarch in balanced electrolyte and glucose injection (Hextend). Patients in the Saline group were given 0.9% sodium chloride solution and 6% hetastarch in 0.9% sodium chloride solution (Hespan). Biochemical indices and acid-base balance were determined. Gastric tonometry was used as a reflection of splanchnic perfusion. Postoperative chloride levels demonstrated a larger increase in the Saline group than the Balanced Fluid group (9.8 vs 3.3 mmol/L, P = 0.0001). Postoperative standard base excess showed a larger decline in the Saline group than the Balanced Fluid group (-5.5 vs -0.9 mmol/L, P = 0.0001). Two-thirds of patients in the Saline group, but none in the Balanced Fluid group, developed postoperative hyperchloremic metabolic acidosis (P = 0.0001). Gastric tonometry indicated a larger increase in the CO2 gap during surgery in the Saline group compared with the Balanced Fluid group (1.7 vs 0.9 kPa, P = 0.0394). In this study, the use of balanced crystalloid and colloid solutions in elderly surgical patients prevented the development of hyperchloremic metabolic acidosis and resulted in improved gastric mucosal perfusion when compared with saline-based solutions.
IMPLICATIONS: This prospective, randomized, blinded trial showed that, in elderly surgical patients, the use of balanced IV solutions can prevent the development of hyperchloremic metabolic acidosis and provide better gastric mucosal perfusion compared with saline-based fluids.

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4. The effect of intravenous lactated Ringer’s solution versus 0.9% sodium chloride solution on serum osmolality in human volunteers.
Anesth Analg. 1999 May;88(5):999-1003
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Animal studies have shown that large volumes of IV lactated Ringer’s solution (LR) decrease serum osmolality, thereby increasing cerebral water. These studies have led to recommendations to limit LR to avoid cerebral edema in neurosurgical patients. Eighteen healthy human volunteers aged 20-48 yr received 50 mL/kg LR over 1 h on one occasion and 0.9% sodium chloride (NS) on another. Venous samples were taken at baseline (T1), at infusion end (T2), and 1 h after T2 (T3). Time until first urination was noted. With LR, serum osmolality decreased by 4+/-3 mOsm/kg from T1 to T2 and increased insignificantly with NS. At T3, osmolality returned almost to baseline in the LR group. Blood pH increased from T1 to T2 with LR by 0.04+/-0.04 and decreased with NS by 0.04+/-0.04. These pH changes persisted at T3. Subjective mental changes occurred only with NS. Abdominal discomfort was more common with NS. Time until first urination was longer with NS (106+/-11 min) than with LR (75+/-10 min) (P < 0.001). In healthy humans, an infusion of large volumes of LR, but not NS, transiently decreased serum osmolality, whereas acidosis associated with NS persisted and urinary output was slower with NS.
IMPLICATIONS: Large volumes of lactated Ringer’s solution administered to healthy humans produced small transient changes in serum osmolality. Large volumes of sodium chloride did not change osmolality but resulted in lower pH.

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All Updates, PHARM, Resus, Trauma

What is 'hypotension' in penetrating trauma?

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I previously noted an article demonstrating that a ‘lowish’ – as opposed to a low – systolic blood pressure is a reason to be vigilant in blunt trauma patients, as a significant increase in mortality has been demonstrated with a systolic blood pressure (SBP) < 110 mmHg.
The same researchers have found similar results in patients with penetrating trauma.
Compared with the reference group with SBP 110-129mmHg, mortality was doubled at SBP 90-109mmHg, was four-fold higher at 70-89mmHg and 10-fold higher at <70mmHg. SBP values ≥150mmHg were associated with decreased mortality.
Systolic blood pressure below 110 mmHg is associated with increased mortality in penetrating major trauma patients: Multicentre cohort study
Resuscitation. 2012 Apr;83(4):476-81
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INTRODUCTION: Non-invasive systolic blood pressure (SBP) measurement is a commonly used triaging tool for trauma patients. A SBP of <90mmHg has represented the threshold for hypotension for many years, but recent studies have suggested redefining hypotension at lower levels. We therefore examined the association between SBP and mortality in penetrating trauma patients.

METHODS: We conducted a prospective cohort study in adult (≥16 years) penetrating trauma patients. Patients were admitted to hospitals belonging to the Trauma Audit and Research Network (TARN) between 2000 and 2009. The main outcome measure was the association between SBP and mortality at 30 days. Multivariate logistic regression models adjusted for the influence of age, gender, Injury Severity Score (ISS) and Glasgow Coma Score (GCS) on mortality were used. RESULTS: 3444 patients with a median age of 30 years (IQR 22.5-41.4), SBP of 126mmHg (IQR 107-142), ISS of 9 (IQR 9-14) and GCS of 15 (IQR 15-15), were analysed. Multivariable logistic regression analysis adjusted for age, gender, severity of injury and level of consciousness showed a cut-off for SBP at <110mmHg, after which increased mortality was observed. Compared with the reference group with SBP 110-129mmHg, mortality was doubled at SBP 90-109mmHg, was four-fold higher at 70-89mmHg and 10-fold higher at <70mmHg. SBP values ≥150mmHg were associated with decreased mortality.

CONCLUSION: We recommend that penetrating trauma patients with a SBP<110mmHg are triaged to resuscitation areas within dedicated, appropriately specialised, high-level care trauma centres.

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