Should we shock with 2J/kg or 4J/kg in Paediatric Defibrillation? The answer seems to be ‘we still don’t know’. Don’t worry – just follow the guidelines (reproduced for you at the bottom)
OBJECTIVE To examine the effectiveness of initial defibrillation attempts. We hypothesized that (1) an initial shock dose of 2 ± 10 J/kg would be less effective for terminating fibrillation than suggested in published historical data and (2) a 4 J/kg shock dose would be more effective.
PATIENTS AND METHODS This was a National Registry of Cardiopulmonary Resuscitation prospective, multisite, observational study of in-hospital pediatric (aged 18 years) ventricular fibrillation or pulseless ventricular tachycardia cardiac arrests from 2000–2008. Termination of ventricular fibrillation or pulseless ventricular tachycardia and event survival after initial shocks of 2 J/kg were compared with historic controls and a 4 J/kg shock dose.
RESULTS Of 266 children with 285 events, 173 of 285 (61%) survived the event and 61 of 266 (23%) survived to discharge. Termination of fibrillation after initial shock was achieved for 152 of 285 (53%) events. Termination of fibrillation with 2 ± 10 J/kg was much less frequent than that seen among historic control subjects (56% vs 91%; P < .001), but not different than 4 J/kg. Compared with 2 J/kg, an initial shock dose of 4 J/kg was associated with lower rates of return of spontaneous circulation (odds ratio: 0.41 [95% confidence interval: 0.21–0.81]) and event survival (odds ratio: 0.42 [95% confidence interval: 0.18–0.98]).
CONCLUSIONS The currently recommended 2 J/kg initial shock dose for in-hospital cardiac arrest was substantially less effective than previously published. A higher initial shock dose (4 J/kg) was not associated with superior termination of ventricular fibrillation or pulseless ventricular tachycardia or improved survival rates. The optimal pediatric defibrillation dose remains unknown.
Effect of defibrillation energy dose during in-hospital pediatric cardiac arrest
Pediatrics. 2011 Jan;127(1):e16-23
Here’s what the guidelines say:
Many AEDs have high specificity in recognizing pediatric shockable rhythms, and some are equipped to decrease (or attenuate) the delivered energy to make them suitable for infants and children <8 years of age. For infants a manual defibrillator is preferred when a shockable rhythm is identified by a trained healthcare provider (Class IIb, LOE C). The recommended first energy dose for defibrillation is 2 J/kg. If a second dose is required, it should be doubled to 4 J/kg. If a manual defibrillator is not available, an AED equipped with a pediatric attenuator is preferred for infants. An AED with a pediatric attenuator is also preferred for children <8 year of age. If neither is available, an AED without a dose attenuator may be used (Class IIb, LOE C). AEDs that deliver relatively high energy doses have been successfully used in infants with minimal myocardial damage and good neurological outcomes
Pediatric Basic Life Support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Full text document
Tag Archives: critical care
GCS in intubated patients
We use the Glasgow Coma Score to describe conscious level, derived from eye opening, verbal response, and motor response.
One problem is that if your patient is intubated, there can’t be a verbal response. There are some ways round this. Imagine your intubated patient opens eys to a painful stimulus and withdraws his limb from one:
- Just give him the lowest score (1) for the verbal component – E2M4V1
- Write ‘V’ (ventilated) or ‘T’ (tube), eg. E2M4VT
- Make it up, based on what you would expect the V score to be based on the E and M scores.
Weird as it sounds, there is a model for this, demonstrated in the paper abstracted below. The Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233).
Don’t worry…if you really want to use this, you don’t have to memorise that equation; there is an online calculator for it here and if you try it you’ll see this patient gets a derived verbal score of 2.3, and therefore a GCS of 7.3! Your decision now whether to round up or down. (In the meantime, I’ve given the patient a V of 1 and called it GCS E2M4VT=7.)
Alternatively, of course, you could try a better validated score that gives more information, the FOUR score, as validated here. The problem is, most people won’t know what you’re talking about.
The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
Meredith W, Rutledge R, Fakhry SM, Emery S, Kromhout-Schiro S.
BACKGROUND: The Glasgow Coma Scale (GCS), which is the foundation of the Trauma Score, Trauma and Injury Severity Score, and the Acute Physiology and Chronic Health Evaluation scoring systems, requires a verbal response. In some series, up to 50% of injured patients must be excluded from analysis because of lack of a verbal component for the GCS. The present study extends previous work evaluating derivation of the verbal score from the eye and motor components of the GCS.
METHODS: Data were obtained from a state trauma registry for 24,565 unintubated patients. The eye and motor scores were used in a previously published regression model to predict the verbal score: Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233). The correlation of the actual and derived verbal and GCS scales were assessed. In addition the ability of the actual and derived GCS to predict patient survival in a logistic regression model were analyzed using the PC SAS system for statistical analysis. The predictive power of the actual and the predicted GCS were compared using the area under the receiver operator characteristic curve and Hosmer-Lemeshow goodness-of-fit testing.
RESULTS: A total of 24,085 patients were available for analysis. The mean actual verbal score was 4.4 +/- 1.3 versus a predicted verbal score of 4.3 +/- 1.2 (r = 0.90, p = 0.0001). The actual GCS was 13.6 + 3.5 versus a predicted GCS of 13.7 +/- 3.4 (r = 0.97, p = 0.0001). The results of the comparison of the prediction of survival in patients based on the actual GCS and the derived GCS show that the mean actual GCS was 13.5 + 3.5 versus 13.7 + 3.4 in the regression predicted model. The area under the receiver operator characteristic curve for predicting survival of the two values was similar at 0.868 for the actual GCS compared with 0.850 for the predicted GCS.
CONCLUSIONS: The previously derived method of calculating the verbal score from the eye and motor scores is an excellent predictor of the actual verbal score. Furthermore, the derived GCS performed better than the actual GCS by several measures. The present study confirms previous work that a very accurate GCS can be derived in the absence of the verbal component.
The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
J Trauma. 1998 May;44(5):839-44 (if you have full text access to Journal of Trauma the best bit about this article is the discussion on pages 844-5 in which surgeons wrestle with the meaning of the word ‘conundrum’ and the spelling of ‘Glasgow’).
Flying Docs and Airways
Flying Doctor Minh Le Cong describes the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team, comprising a doctor and flight nurse. It would be interesting to know how many more patients have been added to the registry since this was submitted. An important contribution to the literature in retrieval medicine.
Objective To describe the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team comprising a doctor and flight nurse.
Method Each intubator completed a study questionnaire at the time of each intubation for indications, complications, overall success, drugs utilised and deployment of rescue airway devices/adjuncts.
Results 76 patients were intubated; 72 intubations were successful. None required surgical airway and three were managed with laryngeal mask airways; the remaining failure was managed with simple airway positioning for transport. There were two cardiac arrests during intubation. Thiopentone and suxamethonium were the predominant drugs used to facilitate intubation.
Conclusion Despite a low rate of endotracheal intubation, the high success rate was similar to other aeromedical organisations’ published airway data. This study demonstrates the utility of the laryngeal mask airway device in the retrieval and transport setting, in particular for managing a failed intubation.
Flying doctor emergency airway registry: a 3-year, prospective, observational study of endotracheal intubation by the Queensland Section of the Royal Flying Doctor Service of Australia
Emerg Med J. 2010 Sep 15. [Epub ahead of print]
Those interested in learning more about this registry, including how often capnography was used, more information about the asystolic arrests, and whether they tried a blind digital intubation, can check this link to a presentation about the registry.
Propofol and the heart
I don’t normally blog about animal studies, but on reading a review of recent(-ish) shock research I was interested in the following piece that describes the effect of diffrent induction agents on rat heart muscle:
Sedation is frequently necessary in patients with septic shock, and therefore Zausig and colleagues investigated the effects of dose-dependent effects of various induction agents (propofol, midazolam, s(+)-ketamine, methohexitone, etomidate) in a Langendorff heart preparation from rats rendered septic by CLP. Propofol exerted the most pronounced depressant effects on both the maximal systolic contraction and the minimal diastolic relaxation, and cardiac work. Furthermore, propofol only adversely deleteriously affected the myocardial oxygen supply- demand ratio. In contrast, s(+)-ketamine was associated with the best maintenance of cardiac function. Within the limits of the study – that is, the use of an ex vivo isolated organ model – the authors concluded that s(+)-ketamine may be an alternative to the comparably inert etomidate, the use of which is, however, limited due to its endocrine side effects.
Of course we should be cautious about extrapolating animal lab work to clinical practice, but this supports my position of vehement opposition to the injudicious use of propofol for RSI in critically ill patients!
Year in review 2009: Critical Care – shock
Critical Care 2010, 14:239 Full text
Prone ventilation in ARDS
Prone ventilation can improve refractory hypoxaemia in ARDS but its effects on mortality have not been impressive in some studies which may be underpowered or include patients with less severe hypoxaemia. An updated meta-analysis showed significantly reduced ICU mortality in the four recent studies that enrolled only patients with ARDS, as opposed to ARDS/ALI (odds ratio = 0.71; 95% confidence interval = 0.5 to 0.99; P = 0.048; number needed to treat = 11). There may also be benefit from a greater duration of prone positioning.
An updated study-level meta-analysis of randomised controlled trials on proning in ARDS and acute lung injury
Critical Care 2011, 15:R6 Full text
Paediatric airway gems
Dr Rich Levitan has made an enormous contribution to the science and practice of emergency airway management, as his bibliography demonstrates. In a new article in Emergency Physicians Monthly entitled ‘Demystifying Pediatric Laryngoscopy’, Rich covers some great tips for optimising laryngoscopic view in kids.
Check this excerpt out for an example:
“During laryngoscopy in infants the epiglottis and uvula are often touching; the epiglottis may be located within an inch of the mouth. Often the epiglottis lies against the posterior pharynx, and it is critical to have a Yankauer to dab the posterior pharynx as the laryngoscope is advanced. Hyperextension of the head pushes the base of tongue and epiglottis backwards against the posterior pharyngeal wall, and makes epiglottis identification more difficult”
Gems like this come thick and fast when you hear or read what Rich has to say. Seven years ago I was left reeling after finishing his ‘Airway Cam Guide to Intubation and Practical Emergency Airway Management‘ which profoundly influenced the way I practice and teach emergency airway skills, including on the Critical Care for Emergency Physicians course.
I’ve finally gotten round to booking a place on one of his courses in March in Baltimore. I’ll let you know how it goes. In the mean time, I’d like to point you toward his training videos as a great educational resource, like this one that demonstrates for novice laryngoscopists the difference between the appearances of trachea and oesophagus, the former having recognisable, defined posterior cartilagenous structures:
Demystifying Pediatric Laryngoscopy
Emergency Physicians Monthly January 19, 2011
A French FIRST in pre-hospital medicine
A contribution has been made to the literature supporting physician intervention in some pre-hospital trauma patients, in the form of the FIRST study: French Intensive care Recorded in Severe Trauma. 
Not exactly the class 1 evidence we’d (well, I’d) like to see, but a prospective study from France comparing outcomes in patients treated by routine pre-hospital providers with those managed in the field by emergency physicians working for SMUR (Service Mobile d’Urgences et de Réanimation). Primary outcome was 30-day mortality. Only patients admitted to an ICU were included, and researchers were not blinded to which group (SMUR vs nonSMUR) patients belonged. A large group of SMUR patients (2513) was compared with a much smaller (190) nonSMUR group.
Patients were sicker in the SMUR group (lower GCS and SpO2, higher Injury Severity Score, higher frequency of abnormal pupils). Unadjusted mortality was not significantly different but when adjustment for ISS and physiological status was made (I don’t really understand how this was done), SMUR care was significantly associated with a reduced risk of 30-day mortality (OR: 0.55, 95% CI: 0.32-0.94, p = 0.03).
Lots of interesting points in this study, most of which ask more questions that they answer. The French pre-hospital physicians have an aggressive approach to trauma resuscitation, doing rapid sequence intubation in more than a half of their patients and even starting catecholamine infusions as a fluid-sparing strategy in shocked patients. The full text link is worth a read for those interested in this area of medicine.
Medical pre-hospital management reduces mortality in severe blunt trauma: a prospective epidemiological study
Critical Care 2011, 15:R34
Full text as provisional PDF
Improved survival with modified CPR
A large randomised controlled trial1 on out-of-hospital cardiac arrest patients compared standard CPR with CPR augmented by two modifications:
- active compression-decompression using a hand-held suction device to compress the chest. The device is attached to the chest of the patient during CPR and the rescuer actively lifts the chest upwards after each compression, which are done at a rate of 80/min
- augmented negative intrathoracic pressure using an impedance threshold device, which is a valve that limits passive air entry into the lungs during chest compressions, thereby reducing intrathoracic pressure and increasing blood flow to vital organs
The primary study endpoint was survival to hospital discharge with favourable neurological function.
Funding issues resulted in premature cessation of the study. 47 (6%) of 813 controls survived to hospital discharge with favourable neurological function compared with 75 (9%) of 840 patients in the intervention group (odds ratio 1·58, 95% CI 1·07–2·36; p=0·019]. 74 (9%) of 840 patients survived to 1 year in the intervention group compared with 48 (6%) of 813 controls (p=0·03), with equivalent cognitive skills, disability ratings, and emotional-psychological statuses in both groups. The overall major adverse event rate did not differ between groups, but more patients had pulmonary oedema in the intervention group (94 [11%] of 840) than did controls (62 [7%] of 813; p=0·015).
An accompanying editorial2 points out that previous studies in animal models of cardiac arrest gave reassuring results for both devices individually and when used together, but results from clinical trials in patients have been mixed for each device when used individually:
- For compression-decompression CPR, a systematic review pooled the existing data for such CPR versus standard CPR in 4162 patients and found no difference in short-term mortality (relative risk 0·98, 95% CI 0·94–1·03) or survival to hospital discharge (0·99, 0·98–1·01). The 2010 CPR guidelines for the USA and Europe do not recommend the use of compression–decompression CPR alone.
- The most current systematic review for the impedance-threshold device showed a significantly improved early survival (relative risk 1·45, 1·16–1·80), and a short-term improved neurological outcome (2·35, 1·30–4·24); however, improved long- term survival did not reach conventional statistical significance (1·48, 0·91–2·41).
The Resuscitation Outcomes Consortium (ROC) PRIMED study3 showed no survival benefit in 8718 patients randomised to standard CPR with an active or sham impedance-threshold device (the Consortium includes the same investigators as the Lancet paper). This was published as an abstract in Circulation recently.
The editorialist has reservations regarding a change in clinical practice resulting from this new study, partly because the trial was stopped prematurely and enrolment of a larger cohort could have changed the findings, and partly because the open use of both devices might have unintentionally introduced bias into the study. Further validation is recommended.
1. Standard cardiopulmonary resuscitation versus active compression-decompression cardiopulmonary resuscitation with augmentation of negative intrathoracic pressure for out-of-hospital cardiac arrest: a randomised trial
Lancet 2011;377:301-11
2. Augmented CPR: rescue after the ResQ trial
Lancet. 2011 Jan 22;377:276-7
3. The Resuscitation Outcomes Consortium ROC) PRIMED Impedance Threshold Device (ITD) Cardiac Arrest Trial: A Prospective, Randomized, Double-Blind, Controlled Clinical Trial
Circulation 2010; 122: 2215–26 (abstr)
Sux vs Roc in ED RSI
Suxamethonium and rocuronium were compared in a database of prospectively recorded cases of RSI in the emergency department.
A total of 327 RSI were included in the final analyses. All patients received etomidate as the induction sedative and were successfully intubated. Of these, 113 and 214 intubations were performed using succinylcholine and rocuronium, respectively.
- The rate of first-attempt intubation success was similar between the succinylcholine and rocuronium groups (72.6% vs. 72.9%, p = 0.95).
- Median doses used for succinylcholine and rocuronium were 1.65 mg/kg (interquartile range [IQR] = 1.26–1.95 mg/kg) and 1.19 mg/kg (IQR = 1–1.45 mg/kg), respectively.
- The median dose of etomidate was 0.25 mg/kg in both groups.
In this study succinylcholine and rocuronium were equivalent with regard to first-attempt intubation success in the ED. This finding is consistent with previous investigations that used doses between 0.9 and 1.2 mg/kg and found similar intubating conditions to succinylcholine at these higher doses; subgroup analyses of studies using a lower rocuronium dose of 0.6 to 0.7 mg/kg had a relative risk favoring succinylcholine for excellent intubating conditions.
The low (in my view) rate of first-attempt intubation success in both groups was (72.6% vs. 72.9%), does make one wonder whether the intubating clinicians optimised their strategy for first-pass success.
Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department
Acad Emerg Med. 2011;18:11-14
Hole in the head? Don't waste the window!
Zampieri and colleagues from Brazil report the use of brain ultrasound in two ICU patients who had had hemicraniectomies.
One of the patients had a subarachnoid haemorrhage with hydrocephalus and an infarct due to vasospasm requiring hemicraniectomy, who subsequently deteriorated with decreasing ventricular catheter drainage, raising suspicion of acute hydrocephalus. Brain ultrasonography confirmed moderate hydrocephalus which was seen to improve after catheter desobstruction.
The authors note: ‘standard ultrasonography can be performed through a hemicraniectomy field and may be helpful in a small group of patients. Since decompressive hemicraniectomy is increasingly being used in critical care medicine, bedside evaluation of the brain using the hemicraniectomy as an insonation window could be useful as a noninvasive triage tool and reduce the need for patient transport to the imaging center.’
Use of ultrasonography in hemicraniectomized patients: a report of two cases
Intensive Care Med. 2010 Dec;36(12):2161-2
Not got a hole in the skull? Could try a bony ultrasound window – compare the clear scans above with this scan of an extradural haematoma