Awake intubation increases intracranial pressure without affecting cerebral blood flow velocity in infants

Premedication for tracheal intubation: A prospective survey in 75 neonatal and pediatric intensive care units*

OBJECTIVE

In children, like in adults, tracheal intubation is a painful procedure that may induce hypertension, tachycardia, and other undesirable hemodynamic disorders. Although premature neonates are very sensitive to pain and vulnerable to its long-term effects, the need for sedation before tracheal intubation is still discussed in neonatal units. Our objective was to investigate the practice of premedication before tracheal intubation in neonatal and pediatric units and determine the influence of premedication on intubating conditions.

DESIGN

We performed a 10-day prospective survey in 75 neonatal and pediatric intensive care units among the 98 licensed in France. A questionnaire was completed for each intubation performed in each surveyed unit.

SUBJECTS

A total of 204 patients were studied: 140 neonates, 52 infants, and 12 children.

MAIN RESULTS

Data on 204 tracheal intubations were collected from 223 that were performed during the study period (participation rate, 91.4%). Premedication was used before intubation for 37.1%, 67.3%, and 91.7% of neonates, infants, and children, respectively (p <.0001). In the subgroup of neonates, premedication was particularly rare for the youngest and the smallest infants. Midazolam was the principle hypnotic used in neonates, whereas propofol was mainly used in children. Opioids or muscle relaxants were used in 16.2% and 4.4% of the patients, respectively. A low success rate and a high incidence of hypoxemia and bradycardia were correlated with the inexperience of the operator. Premedication did not significantly influence either the success rate or the undesirable events associated with tracheal intubation.

CONCLUSION

Use of premedication before tracheal intubation is limited in neonates and increases according to the age of the patient. Midazolam does not seem to be an accurate choice to improve intubating conditions in neonates and infants. Because tracheal intubation is a technique that requires a skill only developed by regular practice, operators who have limited experience with intubating children should be supported by senior operators.

Changes in resuscitation practice at birth

AIM

To investigate secular changes in neonatal resuscitation at birth.

METHODS

Single centre observational study of 17 890 infants born between May 1993 and April 1997. T-piece ventilation was introduced in April 1995.

OBSERVATIONS

Rates and modes of ventilatory resuscitation, early neonatal encephalopathy, neonatal convulsions, and meconium aspiration syndrome; 1 and 5 min Apgar scores; maternal age and method of delivery; paediatric attendance at delivery and resuscitation.

RESULTS

The rate of all forms of ventilatory resuscitation fell during the four year period from 11.0% to 8.9%. The rate of intubation fell from 2.4% to 1.2%. A reduced rate of intubation was seen at all gestations of 30 weeks and above. There was no difference in rates of relevant neonatal problems during the period except for a reduction in neonatal convulsions. The introduction of T-piece ventilation did not contribute to the reduction in intubation in a logistic regression model that included time trend.

CONCLUSION

A marked reduction in the rate of intubation was observed, without any reduction in the efficacy of resuscitation. This may reflect improvements and changing emphasis in resuscitation training.

Fentanyl is more effective than remifentanil at preventing increases in cerebral blood flow velocity during intubation in children

PURPOSE

Controlling the cerebral and systemic hemodynamic responses to laryngoscopy and tracheal intubation may play a role in determining clinical outcome in pediatric neurosurgical patients. This study compared the effects of remifentanil and fentanyl on cerebral blood flow velocity (CBFV) and hemodynamic profile during laryngoscopy and tracheal intubation in children under sevoflurane anesthesia.

METHODS

Sixty healthy children aged two to six years undergoing dental surgery under general anesthesia were enrolled. Each child was randomly assigned to receive a remifentanil or fentanyl infusion, at a rate of 0.75, 1.0, or 1.5 microg x kg(-1) x min(-1) after induction of anesthesia with 2% sevoflurane. Middle cerebral artery blood flow velocity was measured by transcranial Doppler (TCD) sonography. Once a baseline set of hemodynamic variables and TCD measurements were recorded, the opioid infusion was started. Measurements were taken at two-minute intervals, starting four minutes prior to laryngoscopy until four minutes following naso-tracheal intubation.

RESULTS

Remifentanil caused a more significant decrease in mean arterial pressure and CBFV prior to tracheal intubation than did fentanyl (P < 0.001). During laryngoscopy and for two minutes following tracheal intubation, CBFV increased in all remifentanil groups (P < 0.05), whereas it remained stable in all fentanyl groups.

CONCLUSION

This study suggests that fentanyl was more effective than remifentanil at preventing increases in CBFV during and immediately following laryngoscopy and tracheal intubation in children undergoing sevoflurane anesthesia. Fentanyl also seemed to provide a more stable hemodynamic profile prior to laryngoscopy and tracheal intubation when compared to remifentanil.

The effectiveness of premedication for endotracheal intubation in mechanically ventilated neonates. A systematic review

IMPLICATIONS FOR PRACTICE

Extrapolating information from the adult and pediatric literature suggests that awake intubation is probably inappropriate in most neonates. Because premedication attenuates the physiologic responses to intubation, its use is recommended. Adequately skilled staff who have a full understanding of the potential benefits and harms of the interventions used should perform intubation and the administration of premedication in neonates.

IMPLICATIONS FOR RESEARCH

There is a need for well-designed and well-executed randomized controlled trials assessing the effectiveness and potential adverse effects of premedicated intubation in neonates. A valid pain assessment measure or approach should be used. Both short-term and long-term physiologic and clinical outcomes should be incorporated into the trial design.

Facilitation of neonatal nasotracheal intubation with premedication: a randomized controlled trial

OBJECTIVES

To determine if premedication reduces the time and number of attempts by junior medical staff to achieve nasotracheal intubation in neonates. The experimental design was a non-blinded randomized controlled pilot trial. The setting was a perinatal centre in a university teaching hospital.

METHODS

Twenty infants (within the ranges of 25-40 weeks gestation, 650-3660 g and 1 h to 81 days of age) requiring semi-urgent intubation were randomized to either premedication with morphine, atropine and suxamethonium, or to awake intubation.

RESULTS

There were no significant differences between the two groups in regard to prior intubation experience of the staff or infant weight or gestation. The intubation procedure, including intervening events, to completion was significantly faster in premedicated infants (median 60 s vs 595 s; P = 0.002) who were intubated at a younger postnatal age. It took twice as many attempts to intubate a conscious infant (median 2 vs 1; P = 0.010). There was a greater decrease in heart rate from the baseline in the unpremedicated group (mean 68 b.p.m. vs 29 b.p.m.; P = 0.017), but decreases in oxygen saturation were not different. Blood was observed in the oral and nasal passages after intubation in five of the awake infants and in one of the premedicated infants.

CONCLUSIONS

The use of premedication reduces the total time and number of attempts taken to achieve successful nasotracheal intubation of neonates by junior medical staff under supervision.

[Anesthesia-resuscitation for intracranial expansive processes in children]

The most frequent space-occupying cerebral lesions in children are brain tumors, mostly posterior fossa tumors and haematoma resulting from arteriovenous malformation rupture. They result in intracranial hypertension, directly or by compression of the cerebrospinal fluid pathway resulting in hydrocephalus. Their localization and compressive effects are responsible for specific neurological deficits and general problems. Posterior fossa lesions carry a high risk of obstructive hydrocephalus, cranial nerves palsy and brain stem compression, pituitary and chiasmatic tumors a risk of blindness, pituitary deficiency and diabetes insipidus, and cortical tumors a risk of motor deficit and epilepsy. All these parameters must be analyzed before choosing anaesthetic protocols, and surgical techniques. In the presence of life-threatening intracranial hypertension, emergency anaesthetic induction, tracheal intubation and ventilation are life-saving. The specific treatment consists in either hydrocephalus derivation, initial medical treatment with osmotherapy, or rarely surgical removal. In other situations, surgical process requires a highly deep, stable anaesthesia with perfect control of cerebral haemodynamics. Surgical positioning is complex for these long lasting procedures and carries specific risks. The most common is venous air embolism in the sitting position that must be prevented by the use of specific measures. In the postoperative period, the risk of neurological and general complications commands close surveillance, fast track extubation must be adapted on an individual basis.

[The specificity of neurosurgical anesthesia for the child]

Anaesthesia for paediatric neurosurgical procedures presents an interesting challenge to the anaesthesiologist. The child is not simply a small adult. At birth the central nervous system (CNS) development is incomplete and will not be mature until the end of the first year of life. Because of this delay in the maturation of the CNS, several specific pathophysiological and psychological differences ensue. Although one has little control on the child primary lesion, the selection of an anaesthetic technique designed to protect the perilesional area and the recognition of perioperative events and changes may well have a profound effect in the reduction or prevention of significant morbidity. Current neuroanaesthestic practice is based on the understanding of cerebral anatomy and physiology. Paediatric neuroanaesthesiologists must face the added challenge of the physiological differences between developing children and their adult counterparts.

Randomised controlled trial of thiopental for intubation in neonates

AIMS

To determine the effects of premedication with thiopental on heart rate, blood pressure, and oxygen saturation during semi-elective nasotracheal intubation in neonates.

METHODS

A randomised, placebo controlled, non-blinded study design was used to study 30 neonates (mean birthweight 3.27 kg) requiring semi-elective nasotracheal intubation. The babies were randomly allocated to receive either 6 mg/kg of thiopental (study group) or an equivalent volume of physiological saline (control group) one minute before the start of the procedure. Six infants were intubated primarily and 24 were changed from orotracheal to a nasotracheal tube. The electrocardiogram, arterial pressure wave, and transcutaneous oxygen saturation were recorded continuously 10 minutes before, during, and 20 minutes after intubation. Minute by minute measurements of heart rate, heart rate variability, mean blood pressure (MBP) and transcutaneous oxygen saturation (SpO(2)) were computed. The differences for all of these between the baseline measurements and those made during and after intubation were determined. Differences in the measurements made in the study and the control groups were compared using Student's t test.

RESULTS

During intubation, heart rate increased to a greater degree (12.0 vs -0.5 beats per minute, p < 0.03) and MBP increased to a lesser degree (-2.9 vs 4.4 mm Hg; p < 0.002) in the infants who were premedicated with thiopental. After intubation only the changes in MBP differed significantly between the two groups (-3.8 vs 4.6 mm Hg; p < 0.001). There were no significant changes in the oxygen saturation between the two groups during or after intubation. The time taken for intubation was significantly shorter in the study group (p < 0.04).

CONCLUSIONS

The heart rate and blood pressure of infants who are premedicated with thiopental are maintained nearer to baseline values than those of similar infants who receive no premedication. Whether this lessening of the acute drop in the heart rate and increase in blood pressure typically seen during intubation of unmedicated infants is associated with long term advantages to the infants remains to be determined.

Premedication before intubation in UK neonatal units

AIMS

To establish the extent and type of premedication used before intubation in neonatal units in the United Kingdom.

METHODS

A structured telephone survey was conducted of 241 eligible units. Units were subdivided into those that routinely intubated and ventilated babies (routine group) and those that transferred intubated and ventilated babies (transfer group).

RESULTS

Of the units contacted, 239 (99%) participated. Only 88/239 (37%) gave any sedation before intubating on the unit and only 34/239 (14%) had a written policy covering this. Morphine was used most commonly (66%), with other opioids and benzodiazepines used less frequently. Of the 88 units using sedation, 19 (22%) also used paralysis. Suxamethonium was given by 10/19 (53%) but only half of these combined it with atropine. Drug doses varied by factors of up to 200, even for commonly used drugs.

CONCLUSION

Most UK neonatal units do not sedate babies before intubating, despite evidence of physiological and practical benefits. Only a minority have written guidelines, which prohibits auditing of practice.

Rapid sequence intubation of the pediatric patient. Fundamentals of practice

Rapid-sequence intubation and rapid sequence induction of general anesthesia are synonyms and refer to the technique of choice for tracheal intubation in many pediatric patients in the emergency department. The principles of safe practice and basic standards of care uniformly apply to all clinical situations in which the technique is performed. RSI has two basic technical components: induction of general anesthesia and direct laryngoscopy with tracheal intubation. The technique is a prescribed protocol that can be modified slightly by the clinical circumstances. RSI is designed to rapidly create ideal intubating conditions, attenuate pathophysiologic reflex responses to direct laryngoscopy and tracheal intubation, and reduce the risk for pulmonary aspiration. Optimal performance requires appropriate training and knowledge, technical skill, and sound medical judgment. Medical and airway evaluation, careful patient selection, recognition of the need for consultation or safer alternatives, thorough familiarity with appropriate drug management, and attention to detail are essential for minimizing the risk for adverse complications. RSI with a rapid injection of preselected dosages of an anesthetic induction agent and muscle relaxant is the pharmacologic technique of choice. Premedication should not be routinely used. Anticipation, recognition, and management of complications are inherent to the competent delivery of all medical care. The unanticipated difficult airway is arguably the most severe complication of RSI, and all individuals performing the technique must prepare in advance a specific plan for this scenario. As with all such skills or procedures, a quality assurance program is important to monitor care, and individuals practicing RSI need to take appropriate steps to maintain competence.

Clinical uses and controversies of neuromuscular blocking agents in infants and children

OBJECTIVE

To review the pharmacology of neuromuscular blocking drugs (NMBDs), their use in critically ill or injured infants and children, and the relevance of developmental changes in neuromuscular transmission.

DATA SOURCES

Computerized search of the medical literature.

STUDY SELECTION

Studies specifically examining the following were reviewed: a) the developmental changes in neuromuscular transmission; b) the pharmacokinetics and pharmacodynamics of all clinically available NMBDs in neonates, infants, children, and adults; and c) clinical experience with NMBDs in the critical care setting. Particular attention was directed toward studies in the pediatric population.

DATA SYNTHESIS

Neuromuscular transmission undergoes maturational changes during the first 2 months of life. Alterations in body composition and organ function affect the pharmacokinetics and pharmacodynamics of the NMBDs throughout active growth and development. Numerous NMBDs have been developed during the last two decades with unique pharmacologic profiles and potential clinical advantages. The NMBDs are routinely used in critically ill or injured patients of all ages. This widespread use is associated with rare but significant clinical complications, such as prolonged weakness.

CONCLUSIONS

Significant gaps in our knowledge of the pharmacokinetics and pharmacodynamics of NMBDs in infants and children continue to exist. Alterations in electrolyte balance and organ-specific drug metabolism may contribute to complications with the use of NMBDs in the critical care arena.

[Rapid sequence anesthetic induction via prehospital tracheal intubation]

The choice of sedation for emergency intubation remains controversial. This lack of consensus has led to various sedation protocols used in French prehospital care setting. A review of data from the literature suggests that the association etomidate-suxamethonium is probable the best choice for rapid sequence intubations in the prehospital setting. Its benefits include protection against myocardial and cerebral ischaemia, decreased risk of pulmonary aspiration, and a stable haemodynamic profile. Randomized studies are needed to substantiate the advantages of the association etomidate-suxamethonium for rapid sequences intubation in the prehospital setting.

Closure of persistently patent arterial duct and its impact on cerebral circulatory haemodynamics in children

PURPOSE

Closure of a patent arterial duct (PDA) is suggested as a risk factor associated with intraventricular haemorrhage and/or cerebral ischemia in neonates. This study evaluate the effects of transcatheter closure of a patent arterial duct in children on cerebral blood flow velocity.

METHODS

Twelve children, aged from one to eight years were enrolled. Anaesthesia induction consisted of thiopentone, fentanyl and diazepam. Tracheal intubation was facilitated with vecuronium. Anaesthesia was maintained with N2O 70% in O2 and a PaCO2 between 35 to 40 mmHg. No cerebral vasoactive agents were used. Mean arterial pressure (MAP), central venous pressure (CVP), heart rate were continuously recorded. Systolic (Vs) and diastolic (Vd) cerebral blood flow velocity (CBFV) were recorded. Cerebral perfusion pressure (CPP) was calculated. The mean CBFV, the systolic-mean ratio and the cerebral blood volume were estimated from the area under the velocity-time curve (AUC) before PDA closure, immediately after and for 10 min following occlusion.

RESULTS

The mean (+/- SD) age and weight were 30 +/- 22 mo and 13 +/- 5 kg, respectively. Continuous recording during duct closure showed an abrupt increase in Vd (P < 0.05) whereas Vs remained constant. The AUC increased after closure and persisted for 10 min (P < 0.05).

CONCLUSION

This study confirms that closure of a PDA leads to acute changes in intracerebral diastolic flow and volume. This observation gives weight to mechanisms involved in IVH in smaller infants after arterial surgical duct closure. The anaesthetic technique used for arterial duct closure in these procedure could influence these observations.

Use of methohexital for elective intubation in neonates

The effectiveness and safety of a short acting barbiturate, methohexital, was assessed for its use at the time of elective intubation in 18 newborn infants with severe respiratory or cardiac conditions. Evaluation included the speed of action and the degree of relaxation, sedation, and sleep in the first five minutes after administration. All newborn infants were intubated in a fully relaxed and somnolent state. In most infants recovery was completed within five minutes. A slight to moderate oxygen saturation drop was observed during the period of intubation, especially in patients with cyanotic heart disease. The side effects of the drug were twitching and a slight drop in blood pressure. In conclusion, methohexital seems to be a useful drug for short term anaesthesia in neonates, during which, short procedures like elective intubation can be safely performed.