A systematic review of the use of propofol for paediatric procedural sedation (PPS) identified sixty studies and 17 066 published paediatric propofol sedations performed outside the operating theatre setting. The incidence of complications were: desaturation 9.3%, apnoea 1.9%, assisted ventilation 1.4%, hypotension 15.4%, unplanned intubation 0.02%, emesis post procedure 0.14%, laryngospasm 0.1% and bradycardia 0.1%. There are many confounding variables that influence the likelihood of these events: adjunct opiates, propofol dosing strategies and supplemental oxygen. These rates of minor adverse events are similar to that published for ED sedation with other sedation agents
There were no reported incidents of aspiration or emesis during sedation and there were no deaths associated with procedural propofol sedation. The authors conclude: “the published adverse event data for paediatric propofol sedation support its ongoing use in the ED for appropriately selected paediatric patients by experienced physicians who are able to provide advanced cardiorespiratory support.”
Review article: Safety profile of propofol for paediatric procedural sedation in the emergency department
Emerg Med Australas. 2010 Aug;22(4):265-86
During emergency department procedural sedation, some clinicians (myself included) advocate non-invasive capnography for the early detection of apnoea. Others argue against routine administration of oxygen so that if desaturation occurs it provides an earlier more correctable warning of respiratory depression than if it occurs on supplemental oxygen. A Canadian study using prospective data from research on propofol with either ketamine or fentanyl compared changes in capnography with desaturation in sedated patients breathing only room air. Desaturation detectable by pulse oximeter occurred before overt changes in capnometry were identified.
It’s hard to ascertain the relevance of this finding. The authors wisely state ‘these findings should not be extrapolated to patients administered supplemental oxygen where it is possible capnometry may be helpful’. Since I use capnography in the hope that it will assist in the earlier detection of ketamine-associated laryngospasm in children, I’m not going to discard it in favour of waiting for the saturation to fall. Perhaps we just need to be clear that capnography may be more useful at detecting apnoea than hypoventilation.
A comparative evaluation of capnometry versus pulse oximetry during procedural sedation and analgesia on room air
CJEM. 2010 Sep;12(5):397-404
A paper of great interest for those of us who spend a lot of time teaching the use of ketamine describes its history from initial synthesis in the early 1960s. Ketamine pioneer Edward F. Domino, M.D describes how it was first given to humans in 1964: ‘Our findings were remarkable! The overall incidence of side effects was about one out of three volunteers. Frank emergence delirium was minimal. Most of our subjects described strange experiences like a feeling of floating in outer space and having no feeling in their arms or legs.‘
Domino goes on to list interesting anecdotes in ketamine’s history, like how his wife came up with the term ‘dissociative anaesthetic’ and how physicians and their partners experimenting with ketamine in the 1970s tried communicating with dolphins, fell in love, and froze to death in a forest. The pharmacology of ketamine is described along with its effects on pain and even depression.
Taming the ketamine tiger.
Anesthesiology. 2010 Sep;113(3):678-84 Free Full Text
Results from 24 studies on dexmedetomidine were assessed in a meta-analysis to determine the effect on ICU length of stay. The authors concluded that the limited evidence suggests that dexmedetomidine might reduce length of ICU stay in some critically ill patients, but the risk of bradycardia was significantly higher when both a loading dose and high maintenance doses (>0.7 μg/kg/h) were used.
Use of dexmedetomidine as a sedative and analgesic agent in critically ill adult patients: a meta-analysis.
Intensive Care Med. 2010 Jun;36(6):926-39
The College of Emergency Medicine (UK) has updated its guideline on ketamine sedation in children.
The summary is copied below
Full text is available here
Guideline for ketamine sedation of children in Emergency Departments
- Before ketamine is used all other options should be fully considered, including analgesia, reassurance, distraction, entonox, intranasal diamorphine, etc.
- The doses advised for analgesic sedation are designed to leave the patient capable of protecting their airway. There is a significant risk of a failure of sedation if the procedure is prolonged, and the clinician must recognise that the option of general anaesthesia may be preferred in these circumstances.
- There is no evidence that complications are reduced if the child is fasted, however traditional anaesthetic practice favours a period of fasting prior to any sedative procedure. The fasting state of the child should be considered in relation to the urgency of the procedure, but recent food intake should not be considered as an absolute contraindication to ketamine use.
- Ketamine should be only used by clinicians experienced in its use and capable of managing any complications, particularly airway obstruction, apnoea and laryngospasm. The doctor managing the ketamine sedation and airway should be suitably trained and experienced in ketamine use, with a full range of advanced airway skills.
- At least three staff are required: a doctor to manage the sedation and airway, a clinician to perform the procedure and an experienced nurse to monitor and support the patient, family and clinical staff. Observations should be regularly taken and recorded.
- The child should be managed in a high dependency or resuscitation area with immediate access to full resuscitation facilities. Monitoring should include ECG, blood pressure, respiration and pulse oximetry. Supplemental oxygen should be given and suction must be available.
- After the procedure the child should recover in a quiet, observed and monitored area under the continuous observation of a trained member of staff. Recovery should be complete between 60 and 120 minutes, depending on the dose and route used.
- There should be a documentation and audit system in place within a system of clinical governance.
A thorough review of the emergency medicine sedation literature showed there is only one reported case of pulmonary aspiration during emergency procedural sedation, among 4657 adult cases and 17 672 paediatric cases reviewed. The authors of the review remind us that the often (inappropriately in the ED) quoted American Society of Anesthesiology guidelines for fasting prior to general anaesthesia are based on questionable evidence, and there is high-level evidence that demonstrates no link between pulmonary aspiration and non-fasted patients. There is no reason to recommend routine fasting prior to procedural sedation in the majority of patients in the Emergency Department.
An accompanying editorial points out that like other systematic reviews, the methodological flaws of the studies examined are likely to have limited the conclusions of this review.
The review authors and the editorialist agree that despite the lack of evidence linking fasting status to aspiration, selected patients believed to be significantly more prone to aspiration may benefit from risk:benefit assessment prior to sedation.
Something I learned from reading the review: ‘ it is now recognised that asymptomatic aspiration of gastric contents occurs physiologically during normal sleep‘. How about that.
Pre-procedural fasting in emergency sedation
Emerg Med J. 2010 Apr;27(4):254-61
Danish intensivists demonstrate that just bolusing morphine without sedatives results in fewer days on a ventilator and a shortened ICU and hospital stay. Obviously not appropriate for some patients (therapeutic hypothermia, head injury with raised ICP, etc.) and some patients randomised to the no sedation group eventually required sedation. Delirium was three times more common in the no sedation group (20% vs 7%).
A protocol of no sedation for critically ill patients receiving mechanical ventilation: a randomised trial
Lancet. 2010 Feb 6;375(9713):475-80
There is a myth that increased muscular tone caused by ketamine leads to an increased failure rate of joint manipulations when this agent is used for procedural sedation in the ED. This is neither borne out by the published evidence nor our own experience of a series of cases, which have been presented by Louisa Chan at a former (UK) College of Emergency Medicine Conference. At the Australasian College of Emergency Medicine Annual Scientific Conference in Melbourne these data were presented by A/Professor Taylor’s team in Victoria, which provide evidence that procedural failure rate is in fact lower with ketamine than with other commonly used sedatives. Here is the abstract reproduced with the kind permission of A/Prof Taylor:
Failure to successfully complete a procedure following emergency department sedation
DMcD Taylor1,2 for the Emergency Department Sedation Study Investigators
1Austin Health; 2University of Melbourne, Melbourne, Australia
Aims: To determine the nature and incidence of, and factors contributing to, failure to successfully complete a procedure fol- lowing sedation in the ED
Methods: Eleven Australian ED enrolled consecutive adult and paediatric patients between January 2006 and December 2008. Patients were included if a sedative drug was administered for an ED procedure. Data collection was prospective and employed a specifically designed form.
Results: Two thousand six hundred and twenty three patients were enrolled (60.3% male, mean age 39.2 years). Failure to successfully complete the procedure occurred in 148 (5.6%) cases. Most failures occurred with attempted reductions of fractured/dislocated shoulders (35 cases), hips (32), ankles (21) and elbows (14). However, failure rates were highest among fractured/dislocated hips (18.5%), digits (13.7%), femurs (11.1%), mandibles (10.2%) and elbows (9.3%). Failure rates for residents/registrars (5.9%), consultants (5.6%) and nurse practitioners (5.9%) did not differ (P = 0.92). Overall, failure rates for the various drugs (used alone or in combina- tion) did not differ (P = 0.07). However, ketamine (used alone or in combination) was associated with a much lower failure rate (2.9%) than all other sedation drugs used (midazolam 5.8%, propofol 6.5%, fentanyl 6.9%, nitrous oxide 7.1%, and morphine 7.8%).
Conclusion: Procedural failure is uncommon although some pro- cedures are at higher risk, especially dislocated hip reduction. Failure rates do not appear to be affected by the designation of the operator or the sedative drug used. However, ketamine use is associated with lower failure rates. For those procedures at higher risk of failure, the provision of optimal conditions (spe- cialist unit assistance, venue, drug selection) may minimise failure rates.
Emergency Medicine Australasia 2010;22(S1):A52-3
One hundred and thirty-two adults underwent propofol sedation in the emergency department and were randomised into a group in which treating physicians had access to the capnography and a blinded group in which they did not. All patients received supplemental oxygen (3 L/minute) and opioids greater than 30 minutes before. Propofol was dosed at 1.0 mg/kg, followed by 0.5 mg/kg as needed.
Hypoxia (defined as SpO2 less than 93%) was observed in 17 of 68 (25%) subjects with capnography and 27 of 64 (42%) with blinded capnography (p=.035; difference 17%; 95% confidence interval 1.3% to 33%). Capnography identified all cases of hypoxia before onset (sensitivity 100%; specificity 64%), with the median time from capnographic evidence of respiratory depression to hypoxia 60 seconds (range 5 to 240 seconds).
The journal comments: ‘this study provides compelling evidence that capnography can aid in the detection of respiratory depression and reduce hypoxia during procedural sedation.’
However in an accompanying article outlining a pro-con debate for introducing capnography as standard practice in ED procedural sedation, the point is made that the safety benefit purported in this and similar studies is decreased hypoxemia, according to thresholds ranging from 90% to 95%, lasting from 5 to 15 seconds. In the clinical context, many of these events are self-limiting or resolve with minimal interventions such as airway repositioning or supplemental oxygen, and other more clinically relevant outcomes are rarely examined (perhaps due to the rarity of genuinely adverse events in ED procedural sedation by emergency physicians).
Does end tidal CO2 monitoring during emergency department procedural sedation and analgesia with propofol decrease the incidence of hypoxic events? A randomized, controlled trial
Ann Emerg Med. 2010 Mar;55(3):258-64
Records of 4252 patients aged 0-19 who received ketamine were reviewed for documented adverse events. Patients were all American Society of Anesthesiology Class I or II. 102 (2.4%) had an ‘adverse event’, defined as the occurrence of hypoxia by oxygen saturation lower than 93% on room air or clinical cyanosis, documentation of laryngospasm, airway obstruction, or apnea diagnosed clinically or by capnography, stridor, respiratory distress, or hypoventilation or hypercarbia as assessed by capnography. Cases with adverse events were compared with controls who had received ketamine without adverse events, but were not otherwise matched.
Of the adverse events, laryngospasm was documented to have occurred in 29/4252 cases (0.7%), hypoxia in 81/4252 (1.9%), and positive pressure ventilation was required in 33/4252 (0.8%). Intubation was required in one patient (0.023%). Compared with controls, patients with adverse events were more likely to have received IM, as opposed to IV, ketamine, although children who received IM ketamine were more likely to be younger than those who received IV ketamine (4.1 vs 7.9 years).
The retrospective design and other methodological limitations make it harder to draw conclusions other than what we know from existing literature, to which this large series adds: ketamine is given to a lot of kids with few adverse effects; larygnospasm is a real but infrequent occurrence that usually responds to simple manouevres; and intubation is extremely rarely required, but nevertheless may be necessary and therefore those physicians using ketamine should have advanced airway skills.
Serious Adverse Events During Procedural Sedation With Ketamine
Pediatr Emerg Care. 2009 May;25(5):325-8