Nitrous oxide analgesia for intubating preterm neonates: a pilot study

Current status of nitrous oxide use in pediatric patients

Nitrous oxide is one of the most commonly used inhalational anesthetic agents used in practice. It is a cost-effective, pleasant, safe, and versatile anesthetic agent with many desirable properties like good quality analgesia, decreased awareness, accelerated induction and recovery from anesthesia, and reduced utilization of other expensive inhalational agents with potential cost savings. The use of nitrous oxide has been questioned by a lot of studies and case reports perceiving its adverse systemic, hematological, immune, and neurologic adverse effects. However, the literature in the recent past has tried to resolve the controversies related to its use. The concerns over an increase in cardiovascular complications and mortality following nitrous oxide use have been negated by recent data. However, its use in certain vulnerable populations like children with cobalamin and folate deficiency or defects in their metabolic pathways remains a cause of concern for its toxic effects. In this narrative review, we aim to discuss the pharmacological properties of nitrous oxide, the potential advantages and drawbacks of the use of nitrous oxide in children, address the neurodevelopmental and other systemic effects, and throw light on the evidence regarding the safety of nitrous oxide use and its current role in pediatric procedural sedation and anesthesia practice. The literature related to its use in the pediatric population for painful procedures and surgeries has been summarized.

Numerical analysis of mechanical ventilation using high concentration medical gas mixtures in newborns

When administered in relatively high concentrations the mechanical properties of inhaled gas can become significantly different from air. This fact has implications in mechanical ventilation where adequate respiration and injury to the lungs or respiratory muscles can worsen morbidity and mortality. Here we use an engineering pressure loss model to analyze the administration of medical gas mixtures in newborns. The model is used to determine the pressure distribution along the gas flow path. Numerical experiments comparing medical gas mixtures with helium, nitrous oxide, argon, xenon, and medical air as a control, with and without an endotracheal tube obstruction were performed. The engineering pressure loss model was incorporated into a model of mechanical ventilation during pressure control mode, a ventilator mode that is often used for neonates. Results are presented in the form of Rohrer equations relating pressure loss to flow rate for each gas mixture with and without obstruction. These equations were incorporated into a model for mechanical ventilation resulting in pressure, flow rate, and volume curves for the inhalation-exhalation cycle. In terms of accuracy, published values of airway resistance range from 50 to 150 cmH2O/L per second for a normal 3 kg infant. With air, the current results are 55 to 80 cmH2O/L per second for 0.3 to 5 L/min. It is shown that density through inertial pressure losses has a greater influence on airway resistance than viscosity in spite of relatively low flow rates and small airway dimensions of newborns. The results indicate that the high-density xenon mixture can be problematic during mechanical ventilation. On the other hand, low density heliox (a mixture of helium and oxygen) provides a wider margin of safety for mechanical ventilation than the other gas mixtures. The argon or nitrous oxide mixtures considered are only slightly different from air in terms of mechanical ventilation performance.

European Society of Anaesthesiology Task Force on Nitrous Oxide: a narrative review of its role in clinical practice

Nitrous oxide (N₂O) is one of the oldest drugs still in use in medicine. Despite its superior pharmacokinetic properties, controversy remains over its continued use in clinical practice, reflecting in part significant improvements in the pharmacology of other anaesthetic agents and developing awareness of its shortcomings. This narrative review describes current knowledge regarding the clinical use of N₂O based on a systematic and critical analysis of the available scientific literature. The pharmacological properties of N₂O are reviewed in detail along with current evidence for the indications and contraindications of this drug in specific settings, both in perioperative care and in procedural sedation. Novel potential applications for N₂O for the prevention or treatment of chronic pain and depression are also discussed. In view of the available evidence, we recommend that the supply of N₂O in hospitals be maintained while encouraging its economic delivery using modern low flow delivery systems. Future research into its potential novel applications in prevention or treatment of chronic conditions should be pursued to better identify its role place in the developing era of precision medicine.

Assessment of sedation level prior to neonatal intubation: A systematic review

BACKGROUND

Adequate premedication before neonatal endotracheal intubation reduces pain, stress, and adverse physiological responses, diminishes duration and number of attempts at intubation, and prevents traumatic airway injury. Therefore, intubation should not be started until an adequate level of sedation is reached. It is not clear how this should be measured in the clinical situation.

OBJECTIVES

The aim of this study is to provide a systematic review of the usability and validity of scoring systems or other objective parameters to evaluate the level of sedation before intubation in neonates. Secondary aims were to describe parameters that are used to determine the level of sedation and criteria on which the decision to proceed with intubation is based.

METHODS

Literature was searched (January 2017) in the following electronic databases: Embase, Medline, Web of Science, Cochrane Central Registrar of Controlled Trials, Pubmed Publisher, and Google Scholar.

RESULTS

From 1653 hits, 20 studies were finally included in the systematic review. In 7 studies, intubation was started after a predefined time period; in 1 study, preoxygenation was the criterion to start with intubation; and in 12 studies, intubation was started in case of adequate sedation and/or relaxation. Only 4 studies described the use of 3 different objective scoring system, all in the neonatal intensive care unit, which are not validated.

CONCLUSION

No validated scoring systems to assess the level of sedation prior to intubation in newborns are available in the literature. Three objective sedation assessment tools seem promising but need further validation before they can be implemented in research and clinical settings.

Assessment of atropine-sufentanil-atracurium anaesthesia for endotracheal intubation: an observational study in very premature infants

Background

Premedication before neonatal intubation is heterogeneous and contentious. The combination of a short acting, rapid onset opioid with a muscle relaxant is considered suitable by many experts. The purpose of this study was to describe the tolerance and conditions of intubation following anaesthesia with atropine, sufentanil and atracurium in very premature infants.

Methods

Monocentric, prospective observational study in premature infants born before 32 weeks of gestational age, hospitalised in the NICU and requiring semi-urgent or elective intubation. Intubation conditions, heart rate, pulse oxymetry (SpO₂), arterial blood pressure and transcutaneous PCO₂ (TcPCO₂) were collected in real time during 30 minutes following the first drug injection. Repeated physiological measurements were analysed using mixed linear models.

Results

Thirty five intubations were performed in 24 infants with a median post conceptional age of 27.6 weeks and a median weight of 850 g at the time of intubation. The first attempt was successful in 74% and was similar for junior (75%) and senior (74%) operators. The operator rated conditions as “excellent” or “good” in 94% of intubations. A persistent increase in TcPCO₂ as compared to baseline was observed whereas other vital parameters showed no significant variations 5, 10, 15 and 30 minutes after the first drug injection. Eighteen (51%) desaturations (SpO2 less than or equal to 80% for more than 60 seconds) and 2 (6%) bradycardia (heart rate less than100 bpm for more than 60 seconds) were observed.

Conclusion

This drug combination offers satisfactory success rate for first attempt and intubation conditions for the operator without any significant change in heart rate and blood pressure for the patient. However it is associated with frequent desaturations and a possible persistent hypercapnia. SpO₂ and PCO₂ can be significantly modified during neonatal intubation and should be cautiously followed in this high-risk population.

[Implementation of a specific premedication protocol for tracheal intubation in the delivery room. Practice in two level-III hospitals]

Tracheal intubation in neonates is a painful procedure performed daily in the delivery room despite the widespread development of noninvasive ventilation. Specific analgesia is not commonly performed. The objective of this observational study was to compare practices between two level-III centers: one with a specific protocol for premedication before tracheal intubation of newborns in the delivery room, the other without.

RESULTS

One hundred and fifteen neonates were intubated in the delivery room and included over a 4-month period: 25% of them received specific premedication before intubation, exclusively in the center with the protocol. None of the extreme premature neonates (age≤28 gestational weeks) received analgosedation before the procedure. Nalbuphine, midazolam, and sufentanil were mainly used, via the intravenous or intrarectal route. Infants receiving a premedication were significantly heavier and had a greater gestational age than the others (1500 g [range, 1180-2260 g] vs. 1170 [range, 860-1680 g] P=0.003, and 31 GW [range, 29-34 GW] vs. 29 [range, 27-32 GW] P=0.014, respectively). Most pediatricians (85-100%) favored a specific protocol for sedation before tracheal intubation. Implementation of a specific protocol allows specific analgesia to be implemented for newborns undergoing tracheal intubation. Further studies should be conducted to determine the best strategies for pain management during tracheal intubation of neonates, especially in the delivery room.

Intubation in the delivery room: experience with nasal midazolam

BACKGROUND

Neonates are often intubated in the delivery room (DR) without anesthesia because vascular access is impossible.

AIMS

To assess neonatal comfort and adverse events after use of nasal midazolam (nMDZ) for intubation in the DR.

STUDY DESIGN

Prospective data collection over 6months on the intubation of neonates with respiratory distress requiring tracheal instillation of surfactant.

SUBJECTS

Twenty-seven neonates with median (Q25-75) gestational age and birthweight of, respectively, 29 (27-33)weeks and 1270 (817-1942)g received a 0.1mg/kg dose of nMDZ, and intubation was performed at the onset of tonus resolution or apnea.

OUTCOME MEASURES

Comfort was assessed with a scale of hetero-pain assessment and electrical skin conductance monitoring. Continuous pulse oximetry was recorded in the first postnatal hour, with oscillometric blood pressure measurement every 10min.

RESULTS

Seventy percent of the patients required a single dose, with intubation performed 4.8 (3-9)min after administration. Combined electro-clinical assessment found adequate comfort during the procedure in 68% of neonates. Mean blood pressure decreased from 39 (34-44)mmHg before to 31 (25-33)mmHg 1h following nMDZ (p=0.011).

CONCLUSION

nMDZ provided rapid and effective sedation to intubate neonates in the DR but potentially exposed them to hypotension, thus requiring close hemodynamic monitoring.

Applications of nitrous oxide for procedural sedation in the pediatric population

OBJECTIVE

The objective of this review was to provide a general descriptive account of the physical properties, end-organ effects, therapeutic applications, and delivery techniques of nitrous oxide (N2O) as used in the arena of procedural sedation.

DATA SOURCE

A computerized bibliographic search regarding the applications of nitrous for provision of sedation and analgesia during procedures with an emphasis on the pediatric population was performed.

RESULTS

The end-organ effects of N2O have been well described in the operating room setting. Aside from its effects on the central nervous system of sedation and analgesia, N2O may alter intracerebral dynamics and alter cerebral blood flow and intracranial pressure especially in patients with altered intracranial compliance. Effects on ventilation include a dose-related depression of ventilatory function and control of upper airway patency. These effects are generally limited in the absence of comorbid diseases and potentiated by other sedative and analgesic agents. The more clinically significant respiratory effect of N2O on ventilatory function is a dose-dependent depression of the ventilatory response to hypoxemia. Hemodynamic effects include a mild direct depressant effect on myocardial function, which in the absence of comorbid cardiac disease is generally compensated by stimulation of the sympathetic nervous system. Nitrous oxide may potentially aggravate pulmonary hypertension. Additional physiologic effects on neurologic and hematologic function may result in inactivation of the enzyme, methionine synthetase. Recent concern has also been raised regarding the potential effects of N2O on immune function and its relationship to perioperative surgical site infections. Given differences in the solubility, N2O will diffuse into and significantly expand gas-filled cavities. Chronic exposure of health care works to N2O is also a concern. Although there are limited data in the literature to clearly substantiate concerns regarding the reproductive toxicity of occupational exposure to N2O, appropriate scavenging and use of other techniques are mandatory. Nitrous oxide has been shown to be effective for a variety of minor surgical procedures such as venipuncture, intravenous cannula placement, lumbar puncture, bone marrow aspiration, laceration repair, dental care, and minor dermatologic procedures. It is generally as effective as midazolam, with several studies demonstrating it to be more effective. However, its utility is not as great in severely painful procedures such as fracture reduction. Demonstrated advantages to parenteral sedation include a more rapid onset and a shorter recovery time with the majority of patients preferring it to over other agents or agreeing to its use for subsequent procedures. The literature also suggests increased success rates with simple procedures such as intravenous cannula placement when compared with placebo. In general, life-threatening adverse events have not been reported. Most common adverse effects include dysphoria and vomiting. For more painful procedures, combination with another agent may be used, and in all cases, topical or infiltrative local anesthesia is recommended.

CONCLUSIONS

In general, N2O is a useful adjunct for procedural sedation. Given the variety of procedures performed in the pediatric patient, ongoing research is required to identify the most appropriate and effective use of this agent. This may be particularly relevant when evaluating its use for procedures associated with significant pain. In these scenarios, the combination of N2O with other agents needs to be evaluated. Given the potential for adverse effects, strict adherence to published guidelines regarding procedural sedation and monitoring is suggested.

Premedication for endotracheal intubation in the newborn infant

Endotracheal intubation, a common procedure in newborn care, is associated with pain and cardiorespiratory instability. The use of premedication reduces the adverse physiological responses of bradycardia, systemic hypertension, intracranial hypertension and hypoxia. Perhaps more importantly, premedication decreases the pain and discomfort associated with the procedure. All newborn infants, therefore, should receive analgesic premedication for endotracheal intubation except in emergency situations. Based on current evidence, an optimal protocol for premedication is to administer a vagolytic (intravenous [IV] atropine 20 μg/kg), a rapid-acting analgesic (IV fentanyl 3 μg/kg to 5 μg/kg; slow infusion) and a short-duration muscle relaxant (IV succinylcholine 2 mg/kg). Intubations should be performed or supervised by trained staff, with close monitoring of the infant throughout.

Pain management in newborns: from prevention to treatment

All neonates in the Neonatal Intensive Care Unit (NICU) or during the first days of life undergo painful and stressful procedures. Epidemiologic studies have shown that pain induced by these procedures is not effectively prevented or is inadequately treated. Pain experienced during the neonatal period may lead to negative outcomes, especially in preterm neonates. Prevention is the first step of pain management, and practical guidelines should be used in the NICU. Assessment must be done with adequate tools that take into account the infant's pathology and gestational age. Distinguishing between acute and prolonged pain is important for both assessment and treatment. The most common drugs that have been studied for the treatment of pain and stress are opioids, hypnosedatives, and NMDA receptor antagonists. Morphine and fentanyl are most frequently used for acute or prolonged pain in the NICU. They have potent analgesic effects and few immediate or long-term adverse effects. Midazolam is a commonly used hypnosedative, but its adverse effects limit its use. Drugs such as propofol and ketamine have been used for acute painful procedures; however, further research is needed to assess their long-term effects. Use of non-pharmacologic pain management techniques has increased in recent years. These methods are easy, inexpensive, and effective in helping newborns recover from painful procedures. Sweet solutions and non-nutritive sucking, breastfeeding, skin-to-skin mother care, swaddling, and facilitated tucking are the most commonly employed and evaluated non-pharmacologic methods. Hospitals should promote and improve parent involvement in pain management. In-service education and well organized hospital teams are crucial for successful implementation of pain protocols in newborns.

Premedication for tracheal intubation in neonates: confusion or controversy?

Tracheal intubation is performed frequently in the NICU and delivery room. This procedure is extremely distressing, painful, and has the potential for airway injury. Premedication with sedatives, analgesics, and muscle relaxants is standard practice for pediatric and adult intubation, yet the use of these drugs is not common for intubation in neonates. The risks and benefits of using premedications for intubating unstable newborns are hotly debated, although recent evidence shows that premedication for non-urgent or semi-urgent intubations is safer and more effective than awake intubations. This article reviews clinical practices reported in surveys on premedication for neonatal intubation, the physiological effects of laryngoscopy and intubation on awake neonates, as well as the clinical and physiological effects of different drug combinations used for intubation. A wide variety of drugs, either alone or in combination, have been used as premedication for elective intubation in neonates. Schematically, these studies have been of three main types: (a) studies comparing awake intubation versus those with sedation or analgesia, (b) studies comparing different premedication regimens comprising sedatives, analgesics, and anesthetics, and (c) case series of neonates in which some authors have reported their experience with a specific premedication regimen. The clinical benefits described in these studies and the need for pain control in neonates make the case for using appropriate premedication routinely for elective or semi-urgent intubations. Tracheal intubation without the use of analgesia or sedation should be performed only for urgent resuscitations in the delivery room or other life-threatening situations when intravenous access is unavailable.

Propofol compared with the morphine, atropine, and suxamethonium regimen as induction agents for neonatal endotracheal intubation: a randomized, controlled trial

OBJECTIVES

The purpose of this work was to compare the efficacy of propofol, a hypnotic agent, to the regimen of morphine, atropine, and suxamethonium as an induction agent for nonemergency neonatal endotracheal intubation. We hypothesized that propofol aids intubation by allowing the continuation of spontaneous breathing.

PATIENTS AND METHODS

We conducted a randomized, open-label, controlled trial of infants who required nonemergency endotracheal intubation. Primary outcome was successful intubation confirmed by chest auscultation and clinical examination of the infant.

RESULTS

Infants randomly assigned to propofol (n = 33) and the morphine, atropine, and suxamethonium regimen (n = 30) were comparable in median gestational age (27 vs 28 weeks), birth weight (1020 vs 1095 g), weight at intubation (1068 vs 1275 g), and age at intubation (4 vs 3 days). Sleep or muscle relaxation were achieved within 60 seconds in both groups, but time to achieve successful intubation was more than twice as fast with propofol (120 vs 260 seconds). Blood pressure and heart rates were not different, but intraprocedural oxygen saturations were significantly lower in infants on the morphine, atropine, and suxamethonium regimen (trough arterial oxygen saturation: 60% vs 80%). Nasal/oral trauma was less common, and recovery time was shorter (780 vs 1425 seconds) in the propofol group. No significant adverse effects were seen in either group.

CONCLUSIONS

Propofol is more effective than the morphine, atropine, and suxamethonium regimen as an induction agent to facilitate neonatal nasal endotracheal intubation. Importantly, hypoxemia was less severe, probably because of the maintenance of spontaneous breathing. A controlled environment may have promoted the ease of intubation, resulting in less trauma. The shorter duration of action would be advantageous in a compromised infant.

Sédation–analgésie avant intubation trachéale en réanimation néonatale et en salle de naissance: pratiques en France métropolitaine

Tracheal intubation is a painful procedure commonly used in the neonatal intensive care units and in the delivery rooms. It can be complicated by changes in vital signs.

OBJECTIVE

To ascertain the use of sedatives and/or analgesics before tracheal intubation in French neonatal intensive care units and delivery rooms.

METHODS

A survey by questionnaire sent to 58 neonatal intensive care units and 58 maternities.

RESULTS

We obtained 46 responses (79,3%) from the neonatal intensive care units and 38 (65,5%) from the delivery rooms. In neonatal intensive care units, 74% of the newborns received a sedative and/or an analgesic before being intubated, and 60% of the units had specific written guidelines. Opioïds and benzodiazepines were the main drugs used. In the delivery rooms, sedatives or analgesics were only used in 21% of the centres.

CONCLUSION

The use of sedation-analgesia seems to improve in neonatology but is still insufficient in the delivery rooms. The development of specific guidelines and a best learning about the different drugs are necessary.