Tag Archives: procedures

Acute Med, All Updates, Guidelines, ICU, Kids, Resus

Offensive medicine: CT before LP

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I’m getting worn down by clinicians – often other specialists – who insist that CT imaging of the brain is mandatory prior to lumbar puncture in all patients. There is surely a subgroup of patients (especially young ones) in whom the benefit:harm balance of CT comes out in favour of NOT doing the imaging. In these cases, getting the scan is not ‘defensive medicine’ but ‘offensive medicine’ – offending the principle of primum non nocere. During ED shifts I have recently had to perform online searches in order to furnish colleagues and patients’ medically qualified relatives with printouts of the literature on this. This page is here to save me having to repeat those searches. Regarding the practice of performing a routine head CT prior to lumbar puncture to rule out risk of herniation:

  • Mass effect on CT does not predict herniation
  • Lack of mass effect on CT does not rule out raised ICP or herniation
  • Herniation has occurred in patients who did not undergoing lumbar puncture because of CT findings
  • Clinical predictors of raised ICP are more reliable than CT findings
  • CT may delay diagnosis and treatment of meningitis
  • Even in patients in whom LP may be considered contraindicated (cerebral abscess, mass effect on CT), complications from LP were rare in several studies

Best practice, it would seem, is the following

  • If you think CT will show a cause for the headache, do a CT
  • If a CT is indicated for other reasons (depressed conscious level, focal neurology), do a CT
  • If a GCS 15 patient is to undergo LP for suspected (or to rule out) meningitis, and they have a normal neurological exam (including fundi), and are not elderly or immunosuppressed, there is no need to do a CT first.
  • If you’re seriously worried about meningitis and are intent on getting a CT prior to LP, don’t let the imaging delay antimicrobial therapy.

Here are some useful references:

1. The CT doesn’t help

CT head before lumbar puncture in suspected meningitis BestBET evidence summary: In cases of suspected meningitis it is very unlikely that patients without clinical risk factors (immunocompromise/ history of CNS disease/seizures) or positive neurological findings will have a contraindication to lumbar puncture on their CT scan If CT scan is deemed to be necessary, administration of antibiotics should not be delayed. BestBETS website

Computed Tomography of the Head before Lumbar Puncture in Adults with Suspected Meningitis Much cited NEJM paper from 2001 which concludes: “In adults with suspected meningitis, clinical features can be used to identify those who are unlikely to have abnormal findings on CT of the head” N Engl J Med. 2001 Dec 13;345(24):1727-33 Full Text

Cranial CT before Lumbar Puncture in Suspected Meningitis Correspondence in 2002 NEJM including study of 75 patients with pneumococcal meningitis: CT cannot rule out risk of herniation Cranial CT before Lumbar Puncture in Suspected Meningitis N Engl J Med. 2002 Apr 18;346(16):1248-51 Full Text

2. The CT may harm

Cancer risk from CT Paucis verbis card, from the wonderful Academic Life in EM

3. Guidelines say CT is not always needed

National (UK) guidelines on meningitis (community acquired meningitis in the immunocompetent host) available from meningitis.org. , including this box:

Practice Guidelines for the Management of Bacterial Meningitis These 2004 guidelines from the Infectious Diseases Society of America provide the following table listing the recommended criteria for adult patients with suspected bacterial meningitis who should undergo CT prior to lumbar puncture:

Clin Infect Dis. (2004) 39 (9): 1267-1284 Full text

4. This is potentially even more of an issue with paediatric patients

Fatal Lumbar Puncture: Fact Versus Fiction—An Approach to a Clinical Dilemma

An excellent summary of the above mentioned issues presented in a paediatric context, including the following:

On initial consideration a cranial CT would seem to be an appropriate and potentially useful diagnostic study for confirming the diagnosis of cerebral herniataion. The fallacy in this assessment has been emphasized by the finding that no clinically significant CT abnormalities are found that are not suspected on clinical assessments. Further, as previously noted, a normal CT examination may be found at about the time of a fatal herniation. Thus, the practical usefulness of a cranial CT in the majority of pediatric patients is limited to those rare patients whose increased ICP is secondary to mass lesions, not in the initial approach to acute meningitis.

Pediatrics. 2003 Sep;112(3 Pt 1):e174-6 Full Text

The last words should go to Dr Brad Spellberg, who in response to the IDSA’s guidelines wrote an excellent letter summarising much of the evidence at the time, confessed:

Why do we persist in using the CT scan for this purpose, despite the lack of supportive data? I am as guilty of this practice as anyone else, and the reason is simple: I am a chicken.

Clin Infect Dis. (2005) 40 (7): 1061 Full Text

All Updates, Resus

Oxygen prevented hypoxia. Yep.

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Why wouldn’t you give oxygen prophylactically to someone undergoing procedural sedation? One argument is that this will delay the detection of respiratory depression since a pre-oxygenated patient can be hyponoeic/apnoeic for longer prior to desaturation. This is not an issue for those of us who use non-invasive capnography during sedation.
In this randomized trial of oxygen vs air during ED propofol procedural sedation there was less hypoxia when high-flow supplemental oxygen was added. The authors made the following observations:

  • There was no difference between groups in the incidence of respiratory depression, confirming previous research that supplemental oxygen does not exacerbate respiratory depression
  • 5 patients in the compressed air group developed hypoxia without preceding respiratory depression, so capnography cannot be completely relied on in this setting.

They summarise:
“…assuming that capnography is in place to monitor ventilatory function, our results strongly support the routine use of high-flow oxygen during ED propofol sedation”


STUDY OBJECTIVE: We determine whether high-flow oxygen reduces the incidence of hypoxia by 20% in adults receiving propofol for emergency department (ED) sedation compared with room air.

METHODS: We randomized adults to receive 100% oxygen or compressed air at 15 L/minute by nonrebreather mask for 5 minutes before and during propofol procedural sedation. We administered 1.0 mg/kg of propofol, followed by 0.5 mg/kg boluses until the patient was adequately sedated. Physicians and patients were blinded to the gas used. Hypoxia was defined a priori as an oxygen saturation less than 93%; respiratory depression was defined as an end tidal CO(2) greater than 50 mm Hg, a 10% absolute change from baseline, or loss of waveform.

RESULTS: We noted significantly less hypoxia in the 59 patients receiving high-flow oxygen compared with the 58 receiving compressed air (19% versus 41%; P=.007; difference 23%; 95% confidence interval 6% to 38%). Respiratory depression was similar between groups (51% versus 48%; difference 2%; 95% confidence interval -15% to 22%). We observed 2 adverse events in the high-flow group (1 hypotension, 1 bradycardia) and 2 in the compressed air group (1 assisted ventilation, 1 hypotension).

CONCLUSION: High-flow oxygen reduces the frequency of hypoxia during ED propofol sedation in adults.

The Utility of High-Flow Oxygen During Emergency Department Procedural Sedation and Analgesia With Propofol: A Randomized, Controlled Trial
Ann Emerg Med. 2011 Oct;58(4):360-364

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

Easy rapid infusion set up

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Kapoor and Singh's system from the Open Access article - click for explanation

Here’s a nice and simple set up for rapid iv infusions using simple cheap equipment

Full details at the Scandinavian Journal Site
Novel rapid infusion device for patients in emergency situations
Scand J Trauma Resusc Emerg Med. 2011 Jun 10;19:35 (Free Full Text)

All Updates, ICU, Kids, Resus

Is there nothing ketamine can't do?

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As well as the benefits of cardiovascular stability, maintenance of cerebral perfusion pressure, possibly lowering ICP and providing other neuroprotective benefits, ketamine may have other advantages. These are reviewed in a British Journal of Anaesthesia article from which I’ve selected those benefits of interest to practitioners of emergency medicine and critical care.
 

 
Additional Beneficial Effects of Ketamine

  • the dysphoric, or ’emergence’ reactions associated with ketamine may be reduced by pre-administration or co-administration of sedatives, such as benzodiazepines, propofol, dexmedetomidine, or droperidol.

  • ketamine potentiates opioid analgesia in multiple settings, reducing opioid total dose and in some groups of patients reducing postoperative desaturation

  • ketamine has possible anti-inflammatory effects demonstrated in some types of surgical patients

  • ketamine may prevent awareness, recall, or both during general anaesthesia

Ketamine: new uses for an old drug?
Br J Anaesth. 2011 Aug;107(2):123-6

All Updates, PHARM, Resus, Trauma

Lateral trauma position

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Image from sjtrem.com - click for original

The tradition of transporting trauma patients to hospital in a supine position may not be the safest approach in obtunded patients with unprotected airways. The ‘solution’ of having them on an extrication board (backboard / long spine board) to enable rolling them to one side in the event of vomiting may not be practicable for limited crew numbers.
The Norwegians have been including the option of the lateral trauma position in their pre-hospital trauma life support training for some years now.
A questionnaire study demonstrates that this method has successfully been adopted by Norwegian EMS systems.
The method of application is described as:

  • Check airways (look, listen, feel).
  • Apply chin lift/jaw thrust, suction if needed.
  • Apply stiff neck collar.
  • If the patient is unresponsive, but has spontaneous respiration: Roll patient to lateral/recovery position while maintaining head/neck position.
  • Roll to side that leaves the patient facing outwards in ambulance coupé.
  • Transfer to ambulance stretcher (Scoop-stretcher, log-roll onto stretcher mattress, or use multiple helpers, lifting by patient’s clothing).
  • Support head, secure with three belts (across legs, over hip, over shoulder)
  • Manual support of head, supply oxygen, observation, suction, BVM (big valve mask) ventilation when needed.

Different options for supporting the head in the lateral position, according to questionnaire responders, include:

  • putting padding under the head, such as a pillow or similar item (81%)
  • a combination of padding and putting the head on the lower arm (7%)
  • rest the head on the lower arm alone (10%)
  • rest the head on the ground (<1%)

 


BACKGROUND: Trauma patients are customarily transported in the supine position to protect the spine. The Airway, Breathing, Circulation, Disability, and Exposure (ABCDE) principles clearly give priority to airways. In Norway, the lateral trauma position (LTP) was introduced in 2005. We investigated the implementation and current use of LTP in Norwegian Emergency Medical Services (EMS).

METHODS: All ground and air EMS bases in Norway were included. Interviews were performed with ground and air EMS supervisors. Questionnaires were distributed to ground EMS personnel.

RESULTS: Of 206 ground EMS supervisors, 201 answered; 75% reported that LTP is used. In services using LTP, written protocols were present in 67% and 73% had provided training in LTP use. Questionnaires were distributed to 3,025 ground EMS personnel. We received 1,395 (46%) valid questionnaires. LTP was known to 89% of respondents, but only 59% stated that they use it. Of the respondents using LTP, 77% reported access to written protocols. Flexing of the top knee was reported by 78%, 20% flexed the bottom knee, 81% used under head padding. Of 24 air EMS supervisors, 23 participated. LTP is used by 52% of the services, one of these has a written protocol and three arrange training.

CONCLUSIONS: LTP is implemented and used in the majority of Norwegian EMS, despite little evidence as to its possible benefits and harms. How the patient is positioned in the LTP differs. More research on LTP is needed to confirm that its use is based on evidence that it is safe and effective.

The lateral trauma position: What do we know about it and how do we use it? A cross-sectional survey of all Norwegian emergency medical services
Scand J Trauma Resusc Emerg Med. 2011 Aug 4;19:45
Open Access Full Text

All Updates, PHARM, Resus, Trauma

Pre-hospital thoracotomy

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The London Helicopter Emergency Medical Service provides a physician / paramedic team to victims of trauma. One of the interventions performed by their physicians is pre-hospital resuscitative thoracotomy to patients with cardiac arrest due to penetrating thoracic trauma. They have published the outcomes from this procedure over a 15 year period which show an 18% survival to discharge rate, with a high rate of neurologically intact survivors1.
The article was submitted for publication on February 1, 2010, and in the discussion mentions a further two survivors from the procedure performed after conducting the study. It is likely therefore in the year and a half since submission still more patients have been saved. It will be interesting to read future reports from this team as the numbers accumulate; penetrating trauma missions are sadly increasing in frequency.
Having worked for these guys and performed this procedure in the field a few times myself, I can attest to the training and governance surrounding this system. The technique of clamshell thoracotomy is well described 2 and one I would recommend for the non-surgeon.

BACKGROUND: Prehospital cardiac arrest associated with trauma almost always results in death. A case of survival after prehospital thoracotomy was published in 1994 and several others have followed. This article describes the result of prehospital thoracotomy in a physician-led system for patients with stab wounds to the chest who suffered cardiac arrest on scene.
METHODS: A 15-year retrospective prehospital trauma database review identified victims of stab wounds to the chest who suffered cardiac arrest on scene and had thoracotomy performed according to local standard operating procedures.
RESULTS: Overall, 71 patients met inclusion criteria. Thirteen patients (18%) survived to hospital discharge. Neurologic outcome was good in 11 patients and poor in 2. Presenting cardiac rhythm was asystole in four patients, pulseless electrical activity in five, and unrecorded in the remaining four. All survivors had cardiac tamponade. The medical team was present at the time of cardiac arrest for six survivors (good neurologic outcome): arrived in the first 5 minutes after arrest in three patients (all good neurologic outcome), arrived 5 minutes to 10 minutes after arrest in two patients (one poor neurologic outcome), and in one patient (poor neurologic outcome) the period was unknown. Of the survivors, seven thoracotomies were performed by emergency physicians and six by anesthesiologists.
CONCLUSIONS: Prehospital thoracotomy is a well-established procedure in this physician-led prehospital service. Results from this and other similar systems suggest that when performed for the subgroup of patients described, significant numbers of survivors with good neurologic outcome can be expected.

1. Thirteen Survivors of Prehospital Thoracotomy for Penetrating Trauma: A Prehospital Physician-Performed Resuscitation Procedure That Can Yield Good Results
J Trauma. 2011 May;70(5):E75-8
2. Emergency thoracotomy: “how to do it”
Emerg Med J. 2005 January; 22(1):22–24
Full text available here

Acute Med, All Updates, PHARM, Resus

Mouth-to-nose breathing

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Interesting – mouth to nose breathing was more effective than mouth-to-mouth in simulated resuscitations using anaesthetised, apnoeic patients:


BACKGROUND: The authors hypothesized that mouth ventilation by a resuscitator via the nasal route ensures a more patent airway and more effective ventilation than does ventilation via the oral route and therefore would be the optimal manner to ventilate adult patients in emergencies, such as during cardiopulmonary resuscitation. They tested the hypothesis by comparing the effectiveness of mouth-to-nose breathing (MNB) and mouth-to-mouth breathing (MMB) in anesthetized, apneic, adult subjects without muscle paralysis.

METHODS: Twenty subjects under general anesthesia randomly received MMB and MNB with their heads placed first in a neutral position and then an extended position. A single operator performed MNB and MMB at the target breathing rate of 10 breaths/min, inspiratory:expiratory ratio 1:2 and peak inspiratory airway pressure 24 cm H₂O. A plethysmograph was used to measure the amplitude change during MMB and MNB. The inspiratory and expiratory tidal volumes during MMB and MNB were calculated retrospectively using the calibration curve.

RESULTS: All data are presented as medians (interquartile ranges). The rates of effective ventilation (expired volume > estimated anatomic dead space) during MNB and MMB were 91.1% (42.4-100%) and 43.1% (42.5-100%) (P < 0.001), and expired tidal volume with MMB 130.5 ml (44.0-372.8 ml) was significantly lower than with MNB 324.5 ml (140.8-509.0 ml), regardless of the head position (P < 0.001).
CONCLUSIONS: Direct mouth ventilation delivered exclusively via the nose is significantly more effective than that delivered via the mouth in anesthetized, apneic adult subjects without muscle paralysis. Additional studies are needed to establish whether using this breathing technique during emergency situations will improve patient outcomes.

Effectiveness of breathing through nasal and oral routes in unconscious apneic adult human subjects: a prospective randomized crossover trial
Anesthesiology. 2011 Jul;115(1):129-35

All Updates, ICU, Resus, Ultrasound

Ultrasound to detect difficult laryngoscopy

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A pilot study suggests sonographic measurements of neck soft tissue thickness may predict difficult laryngoscopy. Laryngoscopy was difficult in patients with increased thickness of the anterior neck soft tissue at the level of the hyoid bone and thyrohyoid membrane. The authors suggest that anterior neck soft tissue thickness cutoff value of 2.8 cm at the thyrohyoid membrane level can potentially be used to detect difficult laryngoscopy, but that this would require further validation since in this pilot study there were only six subjects in the difficult laryngoscopy group.


Objectives:  Prediction of difficult laryngoscopy in emergency care settings is challenging. The preintubation clinical screening tests may not be applied in a large number of emergency intubations due to the patient’s clinical condition. The objectives of this study were 1) to determine the utility of sonographic measurements of thickness of the tongue, anterior neck soft tissue at the level of the hyoid bone, and thyrohyoid membrane in distinguishing difficult and easy laryngoscopies and 2) to examine the association between sonographic measurements (thickness of tongue and anterior neck soft tissue) and difficult airway clinical screening tests (modified Mallampati score, thyromental distance, and interincisor gap).

Methods:  This was a prospective observational study at an academic medical center. Adult patients undergoing endotracheal intubation for an elective surgical procedure were included. The investigators involved in data collection were blinded to each other’s assessments. Demographic variables were collected preoperatively. The clinical screening tests to predict a difficult airway were performed. The ultrasound (US) measurements of tongue and anterior neck soft tissue were obtained. The laryngoscopic view was graded using Cormack and Lehane classification by anesthesia providers on the day of surgery. To allow for comparisons between difficult airway and easy airway groups, a two-sided Student’s t-test and Fisher’s exact test were employed as appropriate. Spearman’s rank correlation coefficients were used to examine the association between screening tests and sonographic measurements.

Results:  The mean (±standard deviation [SD]) age of 51 eligible patients (32 female, 19 male) was 53.1 (±13.2) years. Six of the 51 patients (12%, 95% confidence interval [CI] = 3% to 20%) were classified as having difficult laryngoscopy by anesthesia providers. The distribution of laryngoscopy grades for all subjects was 63, 25, 4, and 8% for grades 1, 2, 3, and 4, respectively. In this study, 83% of subjects with difficult airways were males. No other significant differences were noted in the demographic variables and difficult airway clinical screening tests between the two groups. The sonographic measurements of anterior neck soft tissue were greater in the difficult laryngoscopy group compared to the easy laryngoscopy group at the level of the hyoid bone (1.69, 95% CI = 1.19 to 2.19 vs. 1.37, 95% CI = 1.27 to 1.46) and thyrohyoid membrane (3.47, 95% CI = 2.88 to 4.07 vs. 2.37, 95% CI = 2.29 to 2.44). No significant correlation was found between sonographic measurements and clinical screening tests.

Conclusions:  This pilot study demonstrated that sonographic measurements of anterior neck soft tissue thickness at the level of hyoid bone and thyrohyoid membrane can be used to distinguish difficult and easy laryngoscopies. Clinical screening tests did not correlate with US measurements, and US was able to detect difficult laryngoscopy, indicating the limitations of the conventional screening tests for predicting difficult laryngoscopy.

Pilot Study to Determine the Utility of Point-of-care Ultrasound in the Assessment of Difficult Laryngoscopy
Acad Emerg Med. 2011 Jul;18(7):754-8

All Updates, Resus

It's up to you….

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Sometimes you have nothing to lose by doing a procedure that you may never have done before, if the patient is going to die or deteriorate without it.
In today’s competency-based-training-and-accreditation climate (a good thing), how does one achieve competence in a procedure that may be too rare to have even been seen, let alone practiced under supervision and formally assessed?
I spend a lot of time and energy trying to convince colleagues and trainees that there are situations where the benefit-harm equation is in favour of acting, despite reservations they may have about inadequate experience or training. These situations often require ‘surgical’ procedures. What they have in common is that they are all relatively simple to perform, but may save a life, a limb, or sight which otherwise may almost certainly be lost.
How best to train for these procedures, some of which may be too rare even for ‘see one, do one, teach one’ in an entire residency program? Simulators? Animal labs? Cadavers?

Slide from 'Making Things Happen' Course

In my view, the answer is to use the most high fidelity simulator in the universe – the human brain. It is those professionals who mentally rehearse the scenario and visualise the procedure over and over who are most likely to act when the patient needs it most. Several colleagues of mine over the years can recount incidents in which the indications for a thoracotomy or hysterotomy were present but they failed to act, talking themselves out of doing the procedure with a range of excuses from ‘I hadn’t had enough training’ to ‘No-one in the room wanted to do it’. Don’t be one of those! Get simulating now – you have all the equipment you need!

Ten steps to making it happen – be prepared
1. Pick a procedure (eg. thoracotomy)
2. Be ABSOLUTELY CLEAR on the indications – this helps remove any doubt when the time comes
3. Learn how to do it (talk to colleagues, read a book)
4. Know where the required equipment is kept
5. Start practicing in your mind – visualise seeing the patient, what you will say to your staff, where you will locate your equipment, what you will do procedurally step-by-step
6. Visualise possible outcomes and what your next steps would be (tamponade plus cardiac wound in a beating heart, tamponade plus wound plus VF, return of spontaneous circulation with bleeding from internal mammary arteries)
7. Read more and talk to more colleagues based on questions arising from your ‘simulations’
8. Travel, go on a course, get access to animal or cadaver labs if that’s an option in your setting
9. Speak to people who have done it in YOUR context (eg. for a resus room thoracotomy, talk to emergency physicians who have done it there, rather than a cardiothoracic surgeon who has only ever done them in the operating room)
10. Find an excuse on shift to talk about it to colleagues and rehearse the steps, locate the equipment, and so on. Remember: REPETITION IS THE MOTHER OF SKILL!

What’s on your list of life/limb/sight-saving procedures that can’t wait for someone else to do? Did I miss any? Should skull trephination be there? Comments welcome!

All Updates, Kids, Resus

Prehospital resuscitative hysterotomy

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My colleagues and I describe a tragic case in this month’s European Journal of Emergency Medicine1. Our physican-paramedic team was called to the home of a collapsed 38-week pregnant female who was in asystolic cardiac arrest. A peri-mortem caesarean delivery was performed by the physician in the patient’s home and the delivered newborn required intubation and chest compressions for bradycardia before resuming good colour and heart rate. Sadly there was ultimately a fatal outcome for both patients, but this case reminds us of the indications for this intervention and for emergency and pre-hospital physicians to be prepared to do it. A literature search yielded only one other reported prehospital case in recent medical literature2.

1.Prehospital resuscitative hysterotomy
Eur J Emerg Med. 2011 Aug;18(4):241-2
2.Out-of-hospital perimortem cesarean section
Prehosp Emerg Care. 1998 Jul-Sep;2(3):206-8