Neonatal Anesthesia


Article Author:
Tanna Boyer


Article Editor:
Stacy Kritzmire


Editors In Chief:
Mark Dreyer
Dustin Constant
Melanie Violand


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
5/29/2019 11:34:19 PM

Introduction

Neonates undergo 1.5 million anesthetics for surgical procedures in the United States every year.[1]  Common surgical procedures for neonates include central line placement, ventriculoperitoneal (VP) shunt placement, tracheostomy, gastrostomy tube placement, circumcision, and inguinal hernia repair.  Neonates are also at risk for necrotizing enterocolitis (NEC) and frequently have intraperitoneal drains placed or need an exploratory laparotomy with possible bowel resection.[2]  Patients with NEC are some of the sickest babies for which pediatric anesthesiologist will care.  Some babies are born with problems that put them at risk for needing imaging or surgical procedures early in life such as tracheoesophageal fistula, congenital diaphragmatic hernia, gastroschisis, omphalocele, and pyloric stenosis.[3]  There are about 40,000 infants born with congenital heart disease every year.[4]  A small percentage of these babies will need a Blalock-Taussig (BT) shunt in the first few days of life to maintain circulation compatible with life.[5] 

It is common across the United States for general anesthesiologists to take care of children 2 years of age and older for basic surgical procedures when they are otherwise reasonably healthy, meaning American Society of Anesthesiology (ASA) Physical Class I or II.  Children under 2, ASA class III and higher, and neonates (babies < 1 month of age) are most often cared for by pediatric anesthesiologists, which is a board-certified subspecialty of the American Board of Anesthesiology.[6]  Common considerations for neonates in the operating room (OR) include temperature control, glucose management, positioning, blood loss, and circulating blood volume.  Bedside cases are performed in the neonatal intensive care unit when neonates are deemed too unstable for transport to the operating room; this is most often due to blood pressure instability (low blood pressure) and/or respiratory failure requiring high flow oscillatory ventilation (HFOV).[7]  Other considerations for neonates undergoing anesthesia include intubation and airway management, respiratory system and metabolic oxygen requirements, cardiovascular system physiology, and pharmacology and drug metabolism physiology.  

Issues of Concern

Thermoregulation in Neonates

Neonates are susceptible to hypothermia in the operating room for a couple of reasons.  First, premature infants have less brown fat and therefore less thermogenesis.  Second, neonates are so small that a proportionally more substantial percentage of skin gets exposed in the operative field during most surgeries.  Third, general anesthesia inhibits central thermoregulation by interfering with hypothalamic function.  It is common for core temperature to drop by 1 to 2 degrees Celsius in the first hour of anesthesia (via convection, radiation, evaporation, and redistribution).[8] 

To prevent heat loss in neonates, it is common to warm ORs to 78 to 80 degrees Fahrenheit before their arrival.  It is also common to use underbody forced air warmers (set to 38 or 43 degrees Celsius), transwarmers, and warming lights.  Hats should also be used to prevent heat loss when the head is not in the surgical field.  If available, warm humidification of the ventilator circuit can also help keep neonates warm.  All fluids on the surgical field should be warmed to body temperature, and all blood products transfused with a fluid warmer.  Minimal exposure during transport to and from the ORs with a hat and transwarmer is also a common practice.  Isolettes should be plugged in and kept warm in preparation for transport.  

Glucose Management 

Neonates and preterm infants are at risk for impaired glycogenolysis and gluconeogenesis.[9]  Neonates have decreased glycogen stores and are prone to hypoglycemia after even short periods of NPO time.  Preterm neonates are at even higher risk for hypoglycemia.[8] Term neonates require 3 to 5 mg/kg/min glucose, and preterm neonates require 5 to 6 mg/kg/min glucose to maintain euglycemia.[8]  Common IV fluid choices for neonates include D10 Water and D10 0.2% NaCl.  TPN and PPN also contain glucose and should be continued intraoperatively if running in the perioperative period.  Stopping TPN/PPN infusions can cause acute hypoglycemia.  Because isotonic fluids are preferable intraoperatively, it is standard of care to run D5 LR for all babies under 6 months of age at maintenance rates.  Fluid boluses can be given using normal saline (NS) or lactated Ringer (LR) solution (without glucose).  A commonly used technique is to give a fluid bolus to a neonate using the number of 10mL normal saline flushes multiplied by their weight in kilograms.  For instance, you can provide a 3.8 kg baby, 40 mL normal saline (10ml/kg fluid bolus) just by giving four 10 mL NS flushes.  

Positioning

Neonates have thin skin and relatively little fat stores, thus making positioning and re-checking of position very important.  Neonates have soft, flexible skulls (intended for easier passage through the birth canal) which can mold and flatten or take the shape of whatever surface on which they are resting.  It is particularly crucial to pay close attention to neonates being placed on a gel horseshoe or other gel headrest, as this can cause pressure necrosis and hair loss in addition to a milder molding/misshapen head problem.[10]  All lines, monitors, and tubing should be meticulously padded prior to surgical draping of a neonate, as their skin is particularly prone to red marks and pressure from anything that is touching them, including a bovie pad.  

Because of their small size, once neonates are prepped and draped for surgery, going under the drapes to check or fix something will likely interrupt your surgical colleagues and may break the sterile field.  Therefore, communication and thoughtful planning and knowledge of where you have placed lines and monitors are vitally important; this is especially true if you will need intraoperative lab draws for arterial blood gases or glucose checks from a finger.  

Intubation and Airway Management

There is emerging evidence that infants less than 1 year of age are more at risk for hypoxia and desaturation during intubation attempts than older kids.  Unpublished data from The Children's Hospital of Philadelphia indicates that up to 20% of babies under 6 months of age require at least two intubation attempts by anesthesia personnel at all levels.  This study suggests that the use of video laryngoscopy may be necessary for primary intubation attempts in all children under 10 kilograms and 1 year of age.[11]  

When intubating a neonate, one has to be cognizant of the anatomy including a larger head, floppy epiglottis, and more cephalad position of the larynx.[12]  Getting a neonate into the sniffing position may involve placement of a shoulder roll, but evidence suggests it may be easier to intubate a neonate in a neutral or slightly flexed position owing to the anatomical considerations above.  

This study suggests that all neonates  over 500gm weight can undergo intubation with a 3.0 uncuffed endotracheal tube,[13] but common practice in pediatric anesthesia indicates that a 3.0 uncuffed endotracheal tube is used for term neonates as well as all neonates  greater than 1 kg weight, and a 2.5 uncuffed endotracheal tube is used for those neonates under 1 kg.  In the United States, neonates are the only pediatric population still intubated with uncuffed endotracheal tubes.[14]  Tochen created the 7-8-9 rule to account for the depth of endotracheal tube placement in neonates.[15]  According to this rule, a 1 kg neonate should have an endotracheal tube taped at 7cm at the gums, a 2 kg neonate should have an endotracheal tube taped at 8cm at the gums, and a 3 kg neonate should have the endotracheal tube taped at 9cm at the gums.[15]  Modification of Tochen's 7-8-9 rule concluded that tube depth in neonates is easily calculable by adding 6cm to the weight in kilograms.[15]  Of course, one must auscultate both lungs and look for equal chest rise and confirmatory end-tidal carbon dioxide as well, but the Tochen rule provides a reasonable estimate of appropriate endotracheal tube depth in neonates.  A chest x-ray is the ultimate confirmatory test for appropriate depth placement of an endotracheal tube.  There is also a consideration for micro preemies less than 750 grams, who may need their endotracheal tube taped at a depth less than 6cm, though this is rare.  

Respiratory System and Metabolic Oxygen Requirements

Alveoli maturation is not complete at birth and in fact, takes up to eight to ten years to fully develop and mature.[16]  Neonates are known to desaturate quickly and take a while to recover once a desaturation occurs; this is because the closing pressure of neonatal airways is very low and occurs very quickly with the loss of ventilation and it will take time for those alveoli to pop back open and participate effectively in ventilation.  It is also important to keep in mind that neonatal oxygen consumption is 6mL/kg/min vs. 3mL/kg/min for an average adult.[17]

Cardiovascular System

Neonatal myocardium is less compliant than adult myocardium, making neonatal cardiac output dependent on heart rate.[18]  Neonatal vasoconstriction is also less responsive to hemorrhage, with a 10% reduction in blood volume causing a 15 to 30% decrease in mean arterial pressure in a newborn infant, meaning neonates may tolerate less blood loss and have decreased compensatory reaction in response to blood loss.[19] 

Circulating Blood Volume and Blood Loss

Neonates have a circulating blood volume equal to 90 mL/kg.[20]  Preterm neonates have a circulating blood volume of 100mL/kg.[21]  This volume means a term baby weighing 3.8 kg will have a circulating blood volume of 342mL.  It is often imperative to calculate maximum allowable blood loss for neonates based off of their starting hemoglobin and the lowest hemoglobin tolerated (usually 8 mg/dL).  Allowable Blood Loss = [EBV x (Hi-Hf)]/Hi where  EBV = Estimated Blood Volume calculation: body wt (kg) x average blood volume (ml/kg), Hi= initial hemoglobin, and Hf= final hemoglobin.  Final hemoglobin is the lowest tolerated hemoglobin for your patient before you would start transfusing.  A good anesthesiologist or anesthetist watches the surgical field closely during neonatal surgeries, as most babies can only lose around 50 to 75mL of blood before considering a transfusion of packed red blood cells as this is usually 20% of their circulating blood volume.  If you are waiting for blood to reach the suction canister during a neonatal surgery, you are too late, as it takes at least 50 mL of blood to reach from the field through the tubing to the suction canister.

Pharmacology and Drug Metabolism

There is limited data in neonates regarding the pharmacokinetics of drugs.  Neonates are a vulnerable population and therefore not usually added to studies by drug companies.  Most drugs used in neonates are used off label, including acetaminophen.  It is essential to keep in mind renal and liver maturation and when the metabolism of certain drugs peaks to normal adult levels, which is generally around 6 months of age.[22]

Clinical Significance

During the first 30 days of life, there are special considerations in planning a safe general anesthetic.  To safely anesthetize a neonate, you must plan your set up and obtain any necessary special equipment in the operating room, decide on weight-based and appropriate anesthetic drugs for neonates, make a plan to keep the neonate warm and hang dextrose containing fluids.  You should also make an appropriate plan and back up plan for intubation, position carefully, and calculate maximum allowable blood loss.  Clear communication between the anesthesia and surgical team is key and will help guide neonatal anesthetic plans.  

Other Issues

Bedside Procedures in the Neonatal Intensive Care Unit (NICU)

When a neonate is not stable enough to transport to the operating room, the anesthesia care team or pediatric anesthesiologist may be asked to provide bedside anesthesia and resuscitation.  This involves special considerations including, use of a ventilator in the NICU, possible use of an oscillator for ventilation, and transport of all necessary anesthesia OR equipment to the NICU for use including, but not limited to: blood/fluid warmers, forced air warmers, overhead heat lamps, transwarmer, IV tubing, anesthesia medications (paralytics, fentanyl, midazolam), pressor medications, saline flushes, endotracheal tubes, intubation equipment (LMA, video laryngoscope, regular laryngoscope, stylet), and oral/nasal airways.  It is important to recall that in the NICU, one may not have the necessary setup and may be dependent on bringing in everything that is needed.  It is a common practice among pediatric anesthesiologists to keep the NICU respiratory therapist present for a case in the NICU, or nearby in case of emergency, as it is not common to manage NICU vents and/or high flow oscillators and may require assistance making urgent ventilation adjustments.  Common challenges encountered while doing surgical cases in the NICU include:

  • Keeping the baby warm
  • Lack of access to IV and arterial lines
  • Lack of access to the airway
  • Difficulty drawing an arterial blood gas with the NICU tubing
  • Rules in the NICU regarding giving medications with blood products (which is common practice in the OR but not in the NICU)

It is also recommended to bring IV tubing or at least an IV extension set to use for IV push medications, as the NICU commonly gives medications via infusion on a pump using high-pressure tubing which is difficult to flush, making it challenging to give IV medications, fluids, and blood when they are needed quickly.  With appropriate planning and communication, surgical cases can be done safely in the NICU.

Complications 

Neonates undergoing anesthesia are at risk for postoperative apnea.[23]  There is an inversely proportional relationship between gestational age and risk for postoperative apnea.[23]  Apnea risk also increases with anemia (hematocrit less than 30).[23]  Term infants born at 37 weeks gestation or older, must be 44 weeks post gestational age to be considered an outpatient surgery candidate.[24]  Preterm infants, born under 37 weeks gestation, generally must be 60 weeks postconceptual age to be considered for outpatient surgeries, though some centers and evidence points towards a range of 56 to 60 weeks postconceptual age.[24]

Enhancing Healthcare Team Outcomes

Most morbidity and mortality in hospitals across the US relate to errors in communication.[25] Handoffs of patient care are particularly vulnerable times for these communication errors.[25]  Since neonates transfer from the NICU to the OR and back, they are at risk for communication errors causing poorer outcomes.  Structured handoffs have been shown to improve morbidity and mortality relative to patient care and are necessary for all transfers of care involving ICU level patients.[26]  Authors of this article recommend a physician to physician handoff from the NICU to the pediatric anesthesiologist before the patient coming down to the OR to gauge basic goals for each patient and NICU plan of care.  Upon arrival to the OR, there should be another structured handoff from the NICU team (including bedside RN, neonatal nurse practitioner, neonatology fellow or resident, and respiratory therapist) to the OR team (anesthesia, circulating RN, surgical team if present).  Often parents arrive with the babies and may have specific questions. Prior to transport back to the NICU, there should be communication, including information on extubation plans (or ventilator needs), blood loss, endotracheal tube and vent settings, fluids given, intravenous access, and meds administered (in particular, paralytics, reversal, antibiotics, and opioids). A structured handoff on arrival in the NICU is also required.  

Across the US, multidisciplinary teams take care of neonatal patients every day.  Pediatric anesthesiologists can work cases by themselves or work in an anesthesia care team model, overseeing nurse anesthetists, anesthesiologist assistants, pediatric anesthesia fellow physicians, or anesthesia resident physicians.  All these various disciplines (physicians, specialists, nursing, pharmacy, therapists) need to communicate and function as an interprofessional team to obtain the best outcomes in care. [Level V] Taking care of neonates in the operating room can be both challenging and very rewarding.  Knowing how a neonate is physiologically and anatomically different from other patients is essential to providing proper care while under anesthesia.  


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Neonatal Anesthesia - Questions

Take a quiz of the questions on this article.

Take Quiz
Which baby will be most susceptible to postoperative apnea events?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 6-day-old patient with trisomy 21 is coming to the operating room for repair of esophageal atresia. The floor nurse reports to you that they lost IV access overnight and did not worry about it because "anesthesia could place one today." The patient is appropriately NPO, and it is decided it is safe to perform a mask induction. During mask induction with 8% sevoflurane and 100% FiO2, the patient's heart rate drops from a baseline of the 140s to 82, and the blood pressure drops from normal to unreadable, so the cuff keeps retrying. Why has this happened?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 3-day old neonate is coming to the operating room for a BT (Blalock-Taussig) shunt. The baby was prenatally diagnosed with tetralogy of Fallot with pulmonary atresia and has was delivered in the high-risk mother-baby unit for immediate PGE1 (prostaglandin E1) infusion to keep the ductus arteriosus patent. What purpose does the BT shunt serve in this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Neonatal Anesthesia - References

References

Hume R,Burchell A,Williams FL,Koh DK, Glucose homeostasis in the newborn. Early human development. 2005 Jan;     [PubMed]
Nasr VG,Davis JM, Anesthetic use in newborn infants: the urgent need for rigorous evaluation. Pediatric research. 2015 Jul;     [PubMed]
Rich BS,Dolgin SE, Necrotizing Enterocolitis. Pediatrics in review. 2017 Dec;     [PubMed]
Dierdorf SF,Krishna G, Anesthetic management of neonatal surgical emergencies. Anesthesia and analgesia. 1981 Apr;     [PubMed]
van der Linde D,Konings EE,Slager MA,Witsenburg M,Helbing WA,Takkenberg JJ,Roos-Hesselink JW, Birth prevalence of congenital heart disease worldwide: a systematic review and meta-analysis. Journal of the American College of Cardiology. 2011 Nov 15;     [PubMed]
Williams JA,Bansal AK,Kim BJ,Nwakanma LU,Patel ND,Seth AK,Alejo DE,Gott VL,Vricella LA,Baumgartner WA,Cameron DE, Two thousand Blalock-Taussig shunts: a six-decade experience. The Annals of thoracic surgery. 2007 Dec;     [PubMed]
Optimal resources for children's surgical care in the United States. Journal of the American College of Surgeons. 2014 Mar;     [PubMed]
McKee M, Operating on critically ill neonates: the OR or the NICU. Seminars in perinatology. 2004 Jun;     [PubMed]
Hillier SC,Krishna G,Brasoveanu E, Neonatal anesthesia. Seminars in pediatric surgery. 2004 Aug;     [PubMed]
Kurth CD,Coté CJ, Postoperative Apnea in Former Preterm Infants: General Anesthesia or Spinal Anesthesia--Do We Have an Answer? Anesthesiology. 2015 Jul;     [PubMed]
Coté CJ,Zaslavsky A,Downes JJ,Kurth CD,Welborn LG,Warner LO,Malviya SV, Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis. Anesthesiology. 1995 Apr;     [PubMed]
Levy A,Kopplin K,Gefen A, Device-related pressure ulcers from a biomechanical perspective. Journal of tissue viability. 2017 Feb;     [PubMed]
SISSON TR,LUND CJ,WHALEN LE,TELEK A, The blood volume of infants. I. The full-term infant in the first year of life. The Journal of pediatrics. 1959 Aug;     [PubMed]
SISSON TR,WHALEN LE,TELEK A, The blood volume of infants. II. The premature infant during the first year of life. The Journal of pediatrics. 1959 Oct;     [PubMed]
Fiadjoe JE,Nishisaki A,Jagannathan N,Hunyady AI,Greenberg RS,Reynolds PI,Matuszczak ME,Rehman MA,Polaner DM,Szmuk P,Nadkarni VM,McGowan FX Jr,Litman RS,Kovatsis PG, Airway management complications in children with difficult tracheal intubation from the Pediatric Difficult Intubation (PeDI) registry: a prospective cohort analysis. The Lancet. Respiratory medicine. 2016 Jan;     [PubMed]
ECKENHOFF JE, Some anatomic considerations of the infant larynx influencing endotracheal anesthesia. Anesthesiology. 1951 Jul;     [PubMed]
Fayoux P,Devisme L,Merrot O,Marciniak B, Determination of endotracheal tube size in a perinatal population: an anatomical and experimental study. Anesthesiology. 2006 May;     [PubMed]
Litman RS,Maxwell LG, Cuffed versus uncuffed endotracheal tubes in pediatric anesthesia: the debate should finally end. Anesthesiology. 2013 Mar;     [PubMed]
Pang LM,Mellins RB, Neonatal cardiorespiratory physiology. Anesthesiology. 1975 Aug;     [PubMed]
Avery ME,Fletcher BD,Williams RG, The lung and its disorders in the newborn infant. Major problems in clinical pediatrics. 1981;     [PubMed]
Friedman WF, The intrinsic physiologic properties of the developing heart. Progress in cardiovascular diseases. 1972 Jul-Aug;     [PubMed]
Young M, Responses of the systemic circulation of the new-born infant. British medical bulletin. 1966 Jan;     [PubMed]
Allegaert K,Mian P,van den Anker JN, Developmental Pharmacokinetics in Neonates: Maturational Changes and Beyond. Current pharmaceutical design. 2017;     [PubMed]
Bates DW,Singh H, Two Decades Since To Err Is Human: An Assessment Of Progress And Emerging Priorities In Patient Safety. Health affairs (Project Hope). 2018 Nov;     [PubMed]
Lane-Fall MB,Pascual JL,Massa S,Collard ML,Peifer HG,Di Taranti LJ,Linehan M,Fleisher LA,Barg FK, Developing a Standard Handoff Process for Operating Room-to-ICU Transitions: Multidisciplinary Clinician Perspectives from the Handoffs and Transitions in Critical Care (HATRICC) Study. Joint Commission journal on quality and patient safety. 2018 Sep;     [PubMed]
Tochen ML, Orotracheal intubation in the newborn infant: a method for determining depth of tube insertion. The Journal of pediatrics. 1979 Dec;     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Surgery-Podiatry Cert Surgery. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Surgery-Podiatry Cert Surgery, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Surgery-Podiatry Cert Surgery, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Surgery-Podiatry Cert Surgery. When it is time for the Surgery-Podiatry Cert Surgery board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Surgery-Podiatry Cert Surgery.