Pediatric Anesthesia Reference Guide

In my dream the Lord did come to me, and He was a shape. It was He Who Walks Behind the Rows.
In my dream the Lord did come to me, and He was a shape. It was He Who Walks Behind the Rows.

UCSF once had an excellent PDF of the essentials to pediatric anesthesia (doses, tube sizes, etc), but that has since been lost to the internet. In searching for a replacement, I came across the Open Anesthesia page on peds, and it has just about everything!

Check it out here: https://www.openanesthesia.org/pediatric_anesthesia_anesthesia_text/

Note that when waking a patient up on precedex (deep) use 0.3mcg/kg as your dose and be sure to extubate deep (1 mac) .

Another reference site is found at Stony Brook, which is a bit more specific to drug doses, see here: https://medicine.stonybrookmedicine.edu/anesthesiology/teaching/peds-drug-dosages

In the interest of internet information preservation, the full text of the website is below:

Pediatric Anesthesia (Anesthesia Text)

Introduction

Anesthesia-related morbidity and mortality is higher in infants than adults, as well as in younger compared to older children. In particular, airway complications are more likely in very young infants. Critical events are highest in infants < 2 kg [Tay et. al. Paediatr Anaesth 11: 711, 2001]

Preoperative Checklist

Warm the room, peds Bear hugger, overhead warming lights, age appropriate headrest and monitors. IV setup in room. See patient early to determine need for premedication needs. For latex precautions, use latex free gloves, black bag on circuit, latex-free IV setup (clear masks are OK, as are ETT, LMA, and pink tape)

  • Warm the room
  • Peds Bair hugger
  • Overhead
  • Warming lights
  • Age appropriate headrest and monitors
  • IV setup in room
  • See patient early to determine need for premedication needs
  • For latex precautions, use latex free gloves, black bag on circuit, latex-free IV setup (clear masks are OK, as are ETT, LMA, and tape)

Pediatric Airway

The tongue is relatively larger, thus making a disproportionate contribution to airway obstruction and moving the glottis anteriorly (especially in children with craniofacial abnormalities, NMJ or CNS disease, tumors, hemangiomas, or URIs). Flexion of an infant’s head may collapse the airway

Pediatric patients often have less pulmonary reserve than adults, and require significantly more oxygen intake, thus they are prone to apnea during direct laryngoscopy

The larynx in infants is located at C3-4 (as opposed to C4-5 in adults). The infant epiglottis is large but short and narrow, possibly making a direct view of the larynx easier than in an adult. Note that the posterior commissure is relatively cephalad, predisposing the anterior sublaryngeal airway to trauma from the ETT. The narrowest portion of the infant airway is the cricoid cartilage, which can lead to resistance after passing an ETT through the cords

Cuffed vs. Uncuffed ETT

In 2009 a multicenter study comparing Microcuff tubes to uncuffed tubes in 2246 children showed that rates of tube exchange were 2.1% with cuffed compared with 30.8% for conventional tubes (p < 0.0001), and that rates of post-extubation stridor were equal in both groups. Furthermore, the cuff significantly improved the accuracy of the ET monitor. Anesthesia providers could ventilate with an average cuff pressure of 10 cm H20 [Weiss M et al. Br J Anaesth 103: 867, 2009].

Pediatric Endotracheal Tube Size

Age Internal Diameter (mm) Depth (cm)
Preterm 2.5 6 – 8
Term 3.0 9 – 10
6 months 3-3.5 10
1 – 2 years 4.0 10 – 11
3 – 4 years 4.5 12 – 13
5 – 6 years 5.0 14 – 15
10 years 6.0 16 – 17

Pediatric Endotracheal Tube Depth

For preemies and neonates (cm) = weight (in kg) + 6 For 1 year or older (cm) = age + 10 cm

Pediatric Airway Equipment

Age Miller Blade
< 32 weeks 00
Term 0 (< 3 kg)
3-18 mo. 1 (3-10 kg)
> 18 mo 2 (> 12 kg)

Pediatric LMA Size

LMA sizes ~ weight (kg) / 20 + 1 (round to nearest 0.5)

Organ Systems

Cardiovascular

Fetal circulation displays 1) increased PVR 2) decreased Qpulm 3) decreased SVR 4) RtoL shunting through foramen ovale. Hypoxemia or acidosis in the newborn can cause a return to fetal circulation

Neonatal hearts are relatively non-compliant and thus stroke volume is relatively fixed – they rely entirely on heart rate to manage cardiac output

Murmurs, abnormal heart sounds, dysrhythmias, and cardiomegaly are all important when noted in a newborn. EKG, CXR, and echo are therefore often required

Normal Physiologic Variables

Age BP (mmHg) HR (/min) RR (/min) Hct (%)
1 kg 45/30 120 – 180 40 – 50
2 kg 55/35 110 – 180 40 – 50
3 kg 65/40 100 – 180 40 – 60 45 – 65
Neonate 75/45 100 – 180 35 – 55 45 – 65
6 mo. 85/50 80 – 180 30 – 50 30 – 40 (nadir)
1 year 95/55 80 – 130 20 – 30 34 – 42
10 year 110/60 60 – 100 20 35 – 43
Adult 110/60 60 – 100 15 40 – 50

Hypovolemia

Hypotension is a late finding in pediatric patients (children may maintain a normal blood pressure until 35% of blood volume is lost). Tachycardia is sensitive but not specific indicator. Prolonged capillary refill (> 2 seconds), especially when combined with tachycardia, is more specific, although it may be difficult to measure. Cold skin and decreased urine output may be present. Weak pulses, mottling, cyanosis, and impaired consciousness may all precede hypotension. In fact, hypotension is an ominous sign in pediatric patients

Hypovolemia in Pediatrics: Signs

  • Tachycardia: sensitive but not specific. Resolution may help guide therapy
  • Delayed Capillary Refill: specific if > 2 seconds
  • Others: weak pulses, mottling, cyanosis, and impaired consciousness (may all precede hypotension), cold skin, decreased urine output
  • Hypotension: late finding. OMINOUS

 

Pulmonary

The lung is not fully formed at birth, and increases from 20 MM alveoli to 300 MM by 18 months of age. Newborn ribcages are particularly compliant and have a circular (non-ellipsoid) configuration as well as a horizontal (non-oblique) insertion of the diaphragm, all of which lead to inefficient diaphragmatic contraction. Worse, full-term infant diaphragms only have 25% type I (slow twitch) fibers, as opposed to 55% in adults

FEN/Renal System

Newborns

Newborns have decreased GFR, decreased ability to excrete solid material, and decreased ability to concentrate urine (ie conserve water). Adult values of GFR are reached between 12 and 24 months of life

Age (weeks) Urine Output (ml/h)
20 5 cc/hr
30 18 cc/hr
40 50 cc/hr

This limited renal resorptive function explains the “physiologic” decrease in bicarbonate (and corresponding acidosis) in newborns (pH 7.26-7.29 at birth, 7.37 at 24h, 7.40 at 1 week)

Estimated blood volume changes with age – at term, the body is 78% water, and adult proportions are not reached until between 9 and 24 months.

Infants have higher plasma chloride and lower bicarbonate (and pH). In the first ten days of life, normal K values may be as high as 6.5 mEq/L. This drops to 3.5-5.5 mEq/L after 2-3 weeks of life. Water exchange is also negative during the first week of life due to limited intake. Infants are at high risk for both over and under hydration

Children

Maintenance Requirements in Children

Weight (kg) Maintenance Requirements in Children (mL/hour)
0-10 4 (mL/kg)
11-20 40 + 2 (mL/kg)
> 20 kg 60 + 1 (mL/kg)

Replacement of Losses

Procedure Insesnsible losses
Non-invasive (inguinal hernia, clubfoot) 0-2 cc/kg/hr
Mildly invasive (uteteral reimplantation) 2-4 cc/kg/hr
Moderately invasive (bowel reanastamosis) 4-8 cc/kg/hr
Significantly invasive (NEC) > 10 cc/kg/hr

Endocrine

Intraoperative Glucose Infants: 4 mg/kg/min = 240 mg/kg/hr maintenance requirements D5 = 50 mg/mL Delivery of D5 @ > 4 mL/kg/hr may lead to hyperglycemia

Hematology

At birth, full term infants have 18-20 g/dL of hemoglobin, 75% of which is HgF (which normalizes by 3-6 months). Hgb will naturally decrease as the infant progresses, reaching a nadir as low as 9-10 g/dL (avg 11.2 g/dL) around 2 months of age [Harriet Lane, 16th ed. CV Mosby, 2002]. In premature infants, however, the nadir may be as low as 6-7 g/dL at 3 or 4 months of age

Cross matched blood should be available for newborn surgery. Assessment of clotting function should be considered because prothrombin as well as factors II, VII, and X are limited in young livers

Blocks

Caudal Block

  • Equipment: 22g B-bevel needle (or angiocath)
  • Drugs: 0.25% bupivacaine or 0.2% ropivacaine +/- morphine 25 ucg/kg or hydromorphone 6 ucg/kg
  • Desired level and volume:
    • Sacral Block: 0.5 ml/kg
    • Midthoracic Block: 1.25 ml/kg

Complicating Issues in Peds

Upper Respiratory Tract Infection

Children recovering from URI are at increased risk for respiratory complications. For short procedures via mask, the increased risk is minimal. If reactive airways accompany the infection, the effects of URI may last 2-7 weeks. In particular, those who already have asthma, bronchopulmonary dysplasia, < 1 yoa, sickle cell, or live in a household of smokers are at high risk, suggesting a “two hit” phenomena [Tait et. al. Anesthesiology 95: 299, 2001]. Bronchial hyperreactivity may last as long as 7 weeks after URI [Collier et. al. Am Rev Resp Dis 117: 47, 1978]. Note that in these patients MASK anesthetics have significantly lower complications than LMA or ETT

If an ETT tube is required, the risk of anesthesia in an infant can be increased as much as 10-fold when compared to an infant with no URI and which does not require ETT. Risk of an LMA are about halfway between those of a facemask and an ETT

Postoperative Croup (< 3 hrs after extubation)

IV decadron 0.25 – 0.5 mg/kg Racemic epinephrine 0.25-0.5 mL of 2.25% solution in 2.5 ml NS

Outpatient Surgery

Inguinal herniorrhaphy, hypospadias repair, and various orthopedic procedures are performed on an outpatient basis in the pediatric population. LMA + caudal block (1 mg/kg 0.125-0.25% bupivacaine) can provide excellent postoperative pain control and lower the anesthetic requirements. A more dilute anesthetic may be used to maintain ambulation

Ex-Premature Infant

Post-operative apnea is always a concern, however it is impossible to fully develop a monitoring protocol [Cote et. al. Anesthesiology 82: 809, 1995]. Apnea is rare after 48 weeks of conceptual age, but the incidence is not zero. The decision of whether or not to admit an ex-premature infant s/p surgery must be individualized. The most conservative approach would be to admit all infants younger than 60 weeks post-conception but this is often impractical. Note that many of these children have chronic lung conditions that last as many as ten years (mostly secondary to reactive airway disease). Hepatic and renal function, as well as developmental delay may also occur.

Cote combined data from eight prospective studies (255 patients) to develop an algorithm based on gestational age, post-conceptual age, apnea at home, size at gestational age, and anemia [Cote CJ et. al. Anesthesiology 82: 809, 1995]. Cotes data showed that the incidence of apnea following inguinal hernia repair did not fall below 5% until gestational age reached 35 weeks and post-conceptual age reached 48 weeks, and that the incidence of apnea following inguinal hernia repair did not fall below 1% until gestational age reached 32 weeks and post-conceptual age reached 56 weeks (or post-gestational 35 weeks with post-conceptual 54 weeks). Any infant that exhibits apnea, has a history of apnea, or is anemic, should not undergo outpatient surgery.

Formulas

Maintenance Requirements in Children

Weight (kg) Maintenance Requirements in Children (mL/hour)
0-10 4 (mL/kg)
11-20 40 + 2 (mL/kg)
> 20 kg 60 + 1 (mL/kg)

Replacement of Losses

Procedure Insesnsible losses
Non-invasive (inguinal hernia, clubfoot) 0-2 cc/kg/hr
Mildly invasive (uteteral reimplantation) 2-4 cc/kg/hr
Moderately invasive (bowel reanastamosis) 4-8 cc/kg/hr
Significantly invasive (NEC) > 10 cc/kg/hr

Intraoperative Glucose

Infants: 4 mg/kg/min = 240 mg/kg/hr maintenance requirements D5 = 50 mg/mL Delivery of D5 @ > 4 mL/kg/hr may lead to hyperglycemia

Medications for Children

Preoperative Medication in Children

PO Nasal IV IM
Midazolam 0.5 – 1.0 mg/kg 0.05 – 0.10 mg/kg
Fentanyl 1 – 3 ucg/kg
Morphine 0.05 – 0.10 mg/kg
Sufentanil 0.25 – 0.5 ucg/kg
Ketamine 2-4 mg/kg 4-6 mg/kg

Resuscitation Medication in Children

  • Epinephrine = 10-100 ucg/kg for arrest (100 ucg/kg in ETT), 1-4 ucg/kg for hypotension
  • Atropine = 0.01 – 0.02 mg/kg (0.3 mg/kg in ETT) – actual dose 0.1 – 1 mg
  • Adenosine = 0.1 mg/kg (max dose 6 mg)
  • Lidocaine = 1-1.5 mg/kg
  • SCh = 2-3 mg/kg
  • Rocuronium 1 mg/kg
  • Calcium chloride = 10-20 mg/kg (dilute to 10 mg/cc or else veins will sclerose, try to give centrally if possible)
  • Bicarbonate = 1 mEq/kg (dilute to 1 mEq/cc or else veins will sclerose)
  • Naloxone = 0.1 mg/kg
  • DEFIBRILLATION = 2 J/kg (can increase up to 4 J/kg)

Preoperative Medication in Children

  • Midazolam 0.05-0.1 mg/kg IV (0.5-1 mg/kg PO, 15 mg max)
  • Methohexital 1-2 mg/kg IV (25-30 mg/kg PR, 500 mg max)
  • Ketamine 1-2 mg/kg IV, 10 mg/kg IM, 5-8 mg/kg PO
  • Sodium Pentothal 1-2 mg/kg IV (separation), 4-6 mg/kg IV (induction)
  • Propofol 0.1-1 mg/kg IV (separation), 2-4 mg/kg IV (induction)
  • Etomidate 0.2-0.3 mg/kg IV

Antibiotic Doses in Children

  • Cefazolin 25 mg/kg q6-8h up to 1-2 grams
  • Cefotaxime 20-30 mg/kg q6h
  • Ampicillin 50-100 mg/kg q6h up to 3 grams
  • Gentamicin 2-2.5 mg/kg q8h (must monitor serum levels, longer interval in renal impairment)
  • Clindamycin 5-10 mg/kg q6-8h up to 900mg
  • Mezlocillinn 50-100 mg/kg q6h up to 2g
  • Vancomycin 10 mg/kg q6h up to 1g

Other Useful Medication in Children

  • Glycopyrrolate 0.01 mg/kg IV, IM, ETT (max 0.4 mg)
  • Morphine 0.05 – 0.1 mg/kg IV (max 0.4 mg/kg)
  • Fentanyl 1-5 ucg/kg IV
  • Ketorolac 0.5 mg/kg IV
  • Tylenol 20 mg/kg PO, 40 mg/kg PR, IV 10-15mg/kg
  • Zofran 0.05-0.15 mg/kg
  • Droperidol 20-25 ucg/kg
  • Dexamethasone 0.1-0.5 mg/kg for pain, N/V prophylaxis
  • Neostigmine 0.07 mg/kg
  • Dexamethasone 0.5-1 mg/kg for tracheal edema
  • Solumedrol 1 mg/kg IV
  • Dexmedatomidine (Precedex) 0.3-0.5mcg/kg slowly at end of case prophylaxis for emergence delerium

Sources

Smith’s Anesthesia for Infants and Children, 8th Edition. Chapters 5, 30, 39 (TABLE 30-5)

PubMed

G E Rasmussen, C M Grande Blood, fluids, and electrolytes in the pediatric trauma patient. Int Anesthesiol Clin: 1994, 32(1);79-101 [PubMed:8144255]

Insulin Pumps and Infusions

Insulin Action Review!
Insulin Action Review!

 

Nice quick reference from the Joslin Diabetes Center and Clinic on management of perioperative blood glucose in patients undergoing surgery, a few things to note:

  • Insulin pumps can be maintained at basal rate throughout surgery
  • Maintenance IVF need NOT have dextrose
  • If starting insulin infusion, give fluids with a substrate, e.g. D5W at 40 ml/hr or D10W at 20 ml/hr
  • if MAJOR surgery start infusion and track throughout case (a line)
  • i/o generally check BG every 2hrs
  • 24hr glucose if on infusion should be 50g
  • Protocols vary by institution for bolus/infusion rates, generally follow local guides (this sheet has one)

See: http://www.joslin.org/Inpatient_Guideline_10-02-09.pdf for more details!

 

PICC vs central line: not that clear cut 

From Patient Safety Solutions: http://www.patientsafetysolutions.com/docs/January_21_2014_The_PICC_Myth.htm

PICC lines (peripherally inserted central catheter)  are often seen as a lower risk alternative to central lines for patients with difficulty iv access, however this is a myth and piccs are not without risk including:

  • Higher risk of upper extremity dvt (2.55 or and account for 35% of all ue dvt)
  • Similar risk of infection!  Meta analysis and systematic reviews show no sig diff in clabsi! 
  • Other complications include thrombophlebitis,and dysfx and malpositioning greater for PICC than central line 

These concerns prompted the ABIM choosing wisely campaign to include piccs on their list of treatments to question:

Don’t place, or leave in place, peripherally inserted central catheters for patient or provider convenience.

Peripherally inserted central catheters (or “PICCs”) are commonly used devices in contemporary medical practice that are associated with two costly and potentially lethal health care-acquired complications: central-line associated bloodstream infection (CLABSI) and venous thromboembolism (VTE). Given the clinical and economic consequences of these complications, placement of PICCs should be limited to acceptable indications (long-term intravenous antibiotics, total parenteral nutrition, chemotherapy and frequent blood draws). PICCs should be promptly removed when acceptable indications for their use ends.

So next time someone recommends a PICC over a central line, think about the indications and necessity! 

Technique: The Dominic Awake Fiberoptic

The Awake Fiberoptic Intubation – The DN Technique

Pre-Op

  1. Educate patient what to expect and what they should do
  2. This education gives you understanding of any language and/or comprehension barriers
  3. D/W surgery team reason for awake fiberoptic (difficult airway, neuro, etc)

Intra-Op

  1. Glycopyrrolate 0.2mg when patient enter room – essential to dry secretions and absorb topical local
  2. 50 fentanyl prn for corporation up to 200mcg, slowly after patient demonstrates understanding
  3. 4-5cc Xylocaine (2%) jelly swish and swallow (numbs oropharynx)
  4. 5% Xylocaine spray (in atomizer), hold nose and have patient take deep breaths, on each inspiration spray oropharynx… confirm that “Xylocaine mist” is inhaled…. continue until mist comes out mouth at the end 0f inhalation.  Repeat for 3 breaths, then pause.
    1. note: if mist comes out too soon patient is breath holding -> reeducate
    2. repeat this process 5x
    3. Tip: put nasal airway in mouth and spray thru while inhaling
  5. Optional Transtracheal Block:
    1. find cricothyroid membrane and topicalize with local
    2. fill a 5cc syringe with 5% xyolocaine, load onto a 20g needle with catheter
    3. insert needle into cricothyroid membrane aspirating continuously until you get air bubbles
    4. if blood, back off and reinsert, same goes for if you hit cartilage
    5. once air aspirated (bubbles), pull out needle (leaving catheter) and then inject 5cc
    6. Patient is expected to cough and this helps spread local (note if patient does not react strongly to this, and you had previously performed atomize technique per above, then likely adequate block!)
  6. At this point, patient is adequately anesthetized and one can proceed with the awake fiberoptic, through use of a mouthpiece of choice.

A few further notes:

  • If reason for awake fiberoptic is neurologic in nature (myelopathy), perform neuro exam with team before and after intubation
  • Versed can interfere with patient cooperation
  • Watch for local toxicity, if patient begins shaking, consider versed +/- propofol
  • watch for hematomas in transtracheal blocks
  • Consider having screen positioned for patient to watch intubation, can reduce trauma of experience.

Thoughts on awake fiberoptics? how do you do it?

 

Carcinoid Triad

Another kind of Triad: The Three Body Problem

Carcinoid Tumors and Anesthesia: Notes from TrueLearn

Carcinoid Tumors: Slow growing, benign, small intestine tumors that can metastasize

Hormonal secreting tumors -> cause cutaneous flushing of head neck and thorax, bronchoconstriction, hypotenion, diarrhea, heart disease

Carcinoid Crisis: triggered by physical/chemical such as histamin release, serotonin, bradykinin

Other triggers include: chemo, tumor necrosis, or succinycholine induced fasciculations!

Anesthestic management: avoid histamine release (succ, atracurium, thiopental, morphine, vancomycin); Desflurane good for patients with liver metastasis as low hepatic metabolism (0.02%); Also the use of NE, epi, Dopamine and isoproternol a/w carcinoid crisis

Carcinoid Heart Disease seen in 60% of patients with carcinoid ->right side:  tricuspid and pulmonic valves (plaque like deposits on valves) with TR as most common finding; 50% of carcinoid deaths are from cardiac involvement

So Carcinoid Triad = flushing, diarrhea and cardiac involvement

Management I/O And Peri-Op:

Carcinoid tumors secrete variety of substances (serotonin, catecholamines, histamine)

Somatostatin therapy is standard of care

Be prepared for rapid BP changes
-alpha/beta blockers for HTN
-Vaso for hypotension, or neo

Avoid: Beta agonists -> increased release of from carinoid !

https://www.openanesthesia.org/carcinoid_crisis_treatment/

 

 

Levo vs. Neo: A Change of the Guards?

Vancomycin IV infiltration, yet we still give through PIV

From A&A May 2016: Should Norepinephrine, Rather than Phenylephrine, Be Considered the Primary Vasopressor in Anesthetic Practice?

http://www.ncbi.nlm.nih.gov/pubmed/27101504

GA = Sympathectomy, decreased NE and Epi concentrations

Phenylephrine (PE, trade name Neosynephrine aka Neo)
pure alpha 1 agonist
increase ABP, decrease HR
CO effect mixed +/- venous return, decreased HR

Norepinephrine (NE, trade name Levophed aka Levo)
alpha1 and beta1, some beta2
relaxation of venous resistance
NE enhances venous return +CO
+ionotropy, little chronotropy
+arterial vasoconstrict
+HR, +SV, +CO

Potency of NE:PE 20:1

NE levels increased in cardiac failure

PeriOp circulating Catecholamine levels

NE and Epi decreased by
-diazepam
-thiopental (even more in uremic)
-midazolam
-pancuronium
-spine surgery + prop or iso

NE and Epi increased by
-Ketamine
-1.5 mac Desflurane
-succinylcholine
-rapid increase in Isoflurane
-intubation
-abdominal surg + sevo/n2o
-emergence/extubation

little effect from roc/vec

Comparing NE to PE in specific studies and circumstances

Aortic stenosis
-PE resulted in higher MAP, no differencve in LV fx vs. Levo

CABG
-PE imparied LV function, unchanged with levo

Pulmonary HTN cardiac surgery pts
-CI maintained with NE, decreased with PE
-NE improved (reduvced) ratio of mean PA pressure to SBP

General Surgery, isoflurance
-NE increased LV performance
-PE decreased LV performance

General Surgery, prop+remi
-both PE/NE decreased CO and HR, increased MAP

C/S Spinal
-PE vs. NE infusion
-NE had same sbp, higher HR, higher CO c/w PE

If LV fx impaired, enhanced afterload from PE -> decreased CO and systemic perfusion

but what about infiltration? Largely overblown as, yes NE 7x more constrictive in radial ARTERY, yet only 76% more vasoconstrictive in veins and concentration of Levo is 20x less than PE

if infiltrate -> give phentolamine