ISAKanyakumari - Anaesthesia Practice in Kanyakumari District

ANAESTHESIA PEARLS

Less Incidence Of Hypotension
Skills for a Pediatric Anesthesiologist
Paediatric Formulas

LESS INCIDENCE OF HYPOTENSION IN SUBARACHNOID

BLOCK FOR CAESAREAN SECTION IN SEVERE PREECLAMPSIA

NAESTHETIC CONSIDERATION IN AIDS PATIENTS

Introduction

It has been believed that severely preeclamptic patients may carry a high risk with use of spinal anesthesia owing to possibility of severe hypotension with maternal and fetal consequences because of reduced plasma volume and of need to limit IV fluids to avoid iatrogenic pulmonary edema, so use of spinal anesthesia has not been popular in preeclampsia. At present several prospective and retrospective studies are available that clearly show that properly administered spinal anesthesia induces a similar incidence and severity of hypotension in patients with severe preeclampsia as epidural anesthesia.

Prospective and retrospective studies

In a large retrospective clinical series, Hood et al studied the blood pressure effects of spinal and epidural anesthesia in severely preeclamptic patients requiring cesarean section. The computerized medical records database was reviewed for all preeclamptic patients having cesarean section between January 1, 1989 and December 31, 1996. They found that Changes in the lowest mean blood pressure were similar after epidural or spinal anesthesia. Intraoperative ephedrine use was similar for both groups.

Spinal versus Epidural Anesthesia for Cesarean Section in Severely Preeclamptic Patients: A Retrospective Survey;

Hood, David D. MD; Curry, Regina RN,

Anesthesiology: May 1999 - Volume 90 - Issue 5 - p 1276–1282

In a prospective cohort study, Aya et al compared the incidence and severity of spinal anesthesia (SA)-associated hypotension in severely preeclamptic (n = 30) versus healthy (n = 30) parturients undergoing cesarean delivery. They found that the severely preeclamptic patients had a less frequent incidence of clinically significant hypotension (16.6% versus 53.3%; P = 0.006), which was less severe and required less ephedrine. The risk of hypotension was almost six times less in severely preeclamptic patients (odds ratio, 0.17; 95% confidence interval, 0.05–0.58; P = 0.006) than that in healthy patients.

Patients with Severe Preeclampsia Experience Less Hypotension During Spinal Anesthesia for Elective Cesarean Delivery than Healthy Parturients: A Prospective Cohort Comparison

Aya, Antoine G. M. MD, PhD; Mangin, Roseline MD, MSc; Vialles, Nathalie MD; Ferrer, Jean-Michel MD; Robert, Colette MD; Ripart, Jacques MD, PhD; de La Coussaye, Jean-Emmanuel MD, PhD

Anesthesia & Analgesia: September 2003 - Volume 97 - Issue 3 - pp 867-872

In their previous study Aya et al showed that, in comparison with term healthy parturients, patients with severe preeclampsia had a less frequent incidence of spinal hypotension, which was less severe and required less ephedrine. In the present study, they hypothesized that these findings were attributable to preeclampsia-associated factors rather than to a smaller uterine mass. The incidence and severity of hypotension were compared between severe preeclamptics (n = 65) and parturients with preterm pregnancies (n = 71), undergoing spinal anesthesia for cesarean delivery. Although the magnitude of the decrease in systolic, diastolic, and mean arterial blood pressure was similar between groups, preeclamptic patients required less ephedrine than women in the preterm group to restore blood pressure to baseline levels. The risk of hypotension in the preeclamptic group was almost 2 times less than that in the preterm group. They concluded that preeclampsia-associated factors, rather than a smaller uterine mass, account for the infrequent incidence of spinal hypotension in preeclamptic patients.

Spinal Anesthesia-Induced Hypotension: A Risk Comparison Between Patients with Severe Preeclampsia and Healthy Women Undergoing Preterm Cesarean Delivery.

Aya, Antoine G. M. MD, PhD; Vialles, Nathalie MD; Tanoubi, Issam MD; Mangin, Roseline MD, MSc; Ferrer, Jean-Michel MD; Robert, Colette MD; Ripart, Jacques MD, PhD; de La Coussaye, Jean-Emmanuel MD, PhD

Anesthesia & Analgesia: September 2005 - Volume 101 - Issue 3 - pp 869-875

In a randomized, multicenter study Visalyaputra et al compared the hemodynamic effects of spinal and epidural anesthesia for cesarean delivery in severely preeclamptic patients. Although the incidence of hypotension and ephedrine requirement was slightly more frequent in the spinal group than in the epidural group, they found evidence that supports the use of spinal anesthesia in severely preeclamptic patients. First, the difference in mean lowest MAP (mean difference, 10 mm Hg; 95% confidence interval, 4–17 mm Hg) did not appear to be clinically significant. Second, the hypotension was easily treated and there was only a brief period of significant hypotension in either group. Third, the neonatal outcomes assessed by the Apgar score and the umbilical arterial blood gas analysis were similar in both groups.

Spinal Versus Epidural Anesthesia for Cesarean Delivery in Severe Preeclampsia: A Prospective Randomized, Multicenter Study.

Visalyaputra, Shusee MD*; Rodanant, Oraluxna MD†; Somboonviboon, Wanna MD†; Tantivitayatan, Kamthorn MD‡; Thienthong, Somboon MD§; Saengchote, Wanawimol MD∥

Anesthesia & Analgesia: September 2005 - Volume 101 - Issue 3 - pp 862-868

In a prospective cohort study, H Ishrat et al compared the incidence and severity of spinal anesthesia (SA) associated hypotension in preeclamptics (n=25) versus healthy parturients (n=25) undergoing cesarean delivery. The preeclamptic patients had a less frequent incidence of clinically significant hypotension, which was less severe and required less ephedrine. The risk of hypotension was significantly less in preeclamptic patients than that in healthy patients. They concluded that spinal anesthesia seemed to be a useful and safe option, and alternative to epidural anesthesia, in preeclamptic patients in setting of large patient turn up for cesarean deliveries.

H Ishrat, A Raja. Spinal anesthesia in preeclamptic parturients. The Internet Journal of Anesthesiology. 2006 Volume 14 Number 2.

GUIDELINES:

As emphasized by practice guidelines from the American Society of Anesthesiologists (ASA)1 and the American College of Obstetricians and Gynecologists (ACOG)2, neuraxial anesthetic techniques, when feasible, are strongly preferred to general anesthesia for preeclamptic parturients.

The reason behind less hypotension in Preeclampsia

Several factors might have contributed to lower incidence of hypotension in Preeclampsia.. One obvious factor should be significantly decreased gestational age in preeclamptics at the time of LSCS. Indeed, healthy parturients, at term or near term, carrying a larger fetus may be at increased risk of aortocaval compression. One more contributing factor may be altered physiology regarding regulation of BP in preeclampsia. BP is regulated via vascular tone by sympathetic and endothelial pathways. Sympathic activity increases the vascular tone. As sympathetic over activity has been suggested in preeclampsia , this may contribute to their hypertension. The sympathetic outflow to vessels may be altered in both preeclamptic and healthy parturients by spinal anesthesia. Regarding the endothelial pathway, the endothelium regulates the vascular tone via endothelium-related vasodilator system that is altered in preeclampsia, decreasing the role of endothelial-dependent relaxation of small resistance vessels. Furthermore, preeclampsia is characterized by an increased production of numerous circulating factors with a potent presser effect on one hand, and by an increased sensitivity of blood vessels to presser drugs because of endothelial damage, on the other hand. These two phenomena contribute to the widespread vasoconstriction seen in preeclamptic patients, are not altered by spinal anesthesia, and could maintain a vascular tone that, ultimately, contributes to limit decrease in BP following intrathecal block in preeclamptic patients. The increased sensitivity of blood vessels to the vasoconstrictory effect of presser agents in preeclampsia may explain easy restoration of BP to baseline with smaller doses of ephedrine in preeclamptics compared to healthy patients.

Conclusion:

The incidence and severity of hypotension following spinal anesthesia is less in preeclampsia compared to healthy parturients, and use of spinal anesthesia , when properly administered and monitored, is a safe alternative to epidural anesthesia in preeclamptic patients including severe preeclampsia.

References :

Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology 2007; 106:843–63.

ACOG Practice Bulletin No. 33: Diagnosis and Management of Preeclampsia and Eclampsia. Obstetrics & Gynecology: January 2002 - Volume 99 - Issue 1 - p 159–167.

Chaudhary S, Salhotra R. Subarachnoid block for caesarean section in severe preeclampsia. J Anaesthesiol Clin Pharmacol , 2011;27:169-73.

Ankichetty SP, Chin KJ, Chan VW, Sahajanandan R, Tan H, Grewal A, Perlas A. Regional anesthesia in patients with pregnancy induced hypertension . J Anaesthesiol Clin Pharmacol 2013;29:435-44.

Important Skills for a Pediatric Anesthesiologist

There are skills intrinsic to the management of children that must be acquired by residents prior to independent practice. These skills, once they have been learned, will make the difference between the enjoyment and dread of the care of children.

The ability to do a mask induction on an infant or child
A part of learning this skill set is losing the anxiety, which often attends anesthetizing someone without an IV. Some of learning this skill is dealing with something small. This is not difficult. Place the mask on the face. Use a non-pungent potent agent in oxygen. Keep your fingers on the mandible and out of the airway.

When the infant is still, put an oral airway in to prevent obstruction by the tongue. Allow the infant to breathe spontaneously if an IV is being placed. Control ventilation if you are trying to attain sufficient depth of anesthesia to place an endotracheal tube without muscle relaxants. A shoulder role sufficient to place the infant’s airway in the sniffing position can be very helpful. Be gentle. It’s a baby.

The ability to establish rapid intravascular access
Look in places where there are veins – the saphenous, the cubital fossa, the dorsum of the hand. Look for the best vein before you poke the kid. Retract the skin before the cannula goes through. Use a small catheter for a small vein. Go slowly.

The ability to assess volume loss in infants
Think about how long it has been since the infant had anything to drink. We say NPO after five am, but in reality it may have been twelve hours or more since the baby had any fluids. When was the last wet diaper? Is the baby perky or somnolent? Are the mucous membranes wet? Remember that potent inhalational agents severely depress the myocardium and this especially reduces cardiac output in dehydrated infants. Be very careful.

The ability to talk to parents
Try to think about what you would feel like if your baby had to go to the operating room and you were putting the baby’s safety in the hands of a complete stranger. Then sit down and calmly talk to the parents about their child and their worries. Play with the baby. Establish rapport. Talk to the parents about your or your attending’s wealth of experience. Be calm.

The ability to assess the airway of an infant
All infants have tough airways because of the small mouth, large tongue and large occiput problem. But some have a small chin, a small mouth or a very large tongue. These children can be a real problem if you don’t recognize this until the muscle relaxants are given. A good rule of thumb is to look up any syndrome that you are unfamiliar with before it becomes a Wednesday Morning Conference.

The ability to recognize a sick child Sick kids look sick. They are listless, somnolent and glassy eyed. They may be mottled or have cold extremities. Their skin will often have a doughy consistency.These infants and children respond poorly to the administration of potent anesthetic agents. Extreme caution should be exercised in the conduct of this child’s care.
In other words low doses administered slowly. Often these children are dehydrated. It makes sense to assess the need for rehydration in a sick child prior to administering an anesthetic.

The ability to manage the pain of surgery in an infant
Infants and children suffer after painful procedures to the same extent as adults. There are many ways to safely control the pain of surgery without added risk.Become familiar with simple blocks that effectively ablate pain after common procedures in children. Discuss the pharmacokinetics and pharmacodynamics of analgesics in infants and older children.

The ability to recognize common postoperative problems of infants and children
Laryngospasm, croup and apnea are the three most common life threatening postoperative problems in infants. These can all be predicted with a remarkable degree of certainty by the clinical situation. Laryngospsm rarely occurs in patients with dry airways in which a non-pungent agent has been used. Sevoflurane is very forgiving.

In a patient that is somnolent, has a wet airway or has been exposed to Desfluane, the risk of airway obstruction is great after removal of an endotracheal tube. Croup is an inflammatory response secondary to a superimposed infectious process or the placement of a large endotracheal tube in a small airway.Croup is tolerated well by children older than three and not at all by infants. This scenario of airway obstruction and respiratory failure can be eliminated by using a small endotracheal tube and leak testing after every intubation in children less than three. Get your attending to demonstrate a leak test if you are uncertain. Apnea and/or periodic breathing are uncommon in infants greater than three kgs and fairly common in infants less than 1500 Gms. Be on the look out!

	The ability to resuscitate a newborn infant in the delivery room The ability to oxygenate and ventilate the depressed newborn is key to improving survival. In this regard the effective use of the bag-valve-mask can be life saving. It is uncommon for newborn infants to fail to respond to adequate delivery of 100% Oxygen.
If this fails consider long-standing acidosis, volume depletion secondary to blood loss, or a central nervous system catastrophe.

The ability to recognize and treat common life threatening problems in newborns
The common life threatening problems in the delivery room include diaphragmatic hernias, severe meconium aspiration, gastroschisis and omphalocoele. Fortunately, with the use of preterm Echo, it is rare for these diagnoses to be made in the delivery room. Because the diagnosis is not in doubt, plans can be made for airway management and other emergent care before the delivery. Meconium aspiration represents the end result of stress and hypoxia in a just delivered infant. Aspirated meconium may produce severe airway obstruction and air trapping sometimes leading to respiratory compromise and death.

Meconium can be suctioned out of the airway prior to the first breath. This procedure is probably warranted if an infant has had a long hypoxic period or has a large amount of thick meconium in the amniotic fluid. Infants that are vigorous at birth or have thin, non-particulate “pea-soup” meconium do not require direct laryngoscopy before the first breath.

SOURCE:

Perioperative physicians at the Kentucky Children's Hospital.

PAEDIATRIC FORMULAS

Normal Physiological 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

Normal Urine Output

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

Normal resting heart rates of infants and children

	HEART RATE (beats/min)
Age	Mean	Range (±2 SDs)
0 to 24 hr	119	94 to 145
1 to 7 days	133	100 to 175
8 to 30 days	163	115 to 190
1 to 3 mo	152	124 to 190
3 to 12 mo	140	111 to 179
1 to 3 yr	126	98 to 163
3 to 5 yr	98	65 to 132
5 to 8 yr	96	70 to 115
8 to 16 yr	77	55 to 105

Modified from Liebman J, Plonsey R, Gilette PC, editors: Pediatric electrocardiography. Baltimore, MD, 1982, Williams & Wilkins.

Age-Related Circulatory Variables

Age	Heart Rate (Beats/min)	Systolic Blood Presssure (mm Hg)	Diastolic Blood Pressure (mm Hg)	Stroke Volume (mL/Beat)	Cardiac Index (L/min/m2)	Oxygen Consumption (mL/kg/min)	Hemoglobin Concentration (g/dL)	P50 (mm Hg)
Term newborn	133 ± 18	80 ± 16	46 ± 16	4.5 ± 5.0	2.5 ± 0.6	6.0 ± 1.0	16.5 ± 1.5	18
6 mo	120 ± 20	89 ± 29	60 ± 10	7.4 ± 2.0	2.0 ± 0.5	5.0 ± 0.9	11.5 ± 1.0	24
12 mo	120 ± 20	96 ± 30	66 ± 25	11.5 ± 3.0	2.5 ± 0.6	5.2 ± 0.9	12.0 ± 0.75	—
2 yr	105 ± 25	99 ± 25	64 ± 25	16.9 ± 4.5	3.1 ± 0.7	6.4 ± 1.2	12.5 ± 0.5	27
5 yr	90 ± 10	94 ± 14	55 ± 9	27.8 ± 7.5	3.7 ± 0.9	6.0 ± 1.1	12.5 ± 0.5	—
12 yr	70 ± 17	113 ± 18	59 ± 10	53.5 ± 14.5	4.3 ± 1.1	3.3 ± 0.6	13.5 ± 1.0	—
Adult	75 ± 5	—	—	85.5 ± 6.0	3.7 ± 0.3	3.4 ± 0.6	14.0 ± 1.0	27

Estimates of circulating blood volume

Patient	Blood Volume (mL/kg)
Premature newborn	90 to 100
Full-term newborn	80 to 90
3 mo to 1 yr	75 to 80
3 to 6 yr	70 to 75
>6 yr	65 to 70

Age-Dependent Respiratory Variables: Normal Values *

	Newborn	6 mo	12 mo	3 yr	5 yr	12 yr	Adult
Respiratory rate (breaths/min)	50 ± 10	30 ± 5	24 ± 6	24 ± 6	23 ± 5	18 ± 5	12 ± 3
Tidal volume (mL)	21	45	78	112	270	480	575
Minute ventilation (L/min)	1.05	1.35	1.78	2.46	5.5	6.2	6.4
Alveolar ventilation (mL/min)	385	—	1245	1760	1800	3000	3100
Dead space–tidal volume ratio	0.3	0.3	0.3	0.3	0.3	0.3	0.3
Oxygen consumption (mL/kg/min)	6 ± 1.0	5 ± 0.9	5.2 ± 0.9	±	6.0 ± 1.1	3.3 ± 0.6	3.4 ± 0.6
Vital capacity (mL)	120	—	—	870	1160	3100	4000
Functional residual capacity (mL)	80	—	—	490	680	1970	3000
Total lung capacity (mL)	160	—	—	1100	1500	4000	6000
Closing volume as a percentage of vital capacity	—	—	—	—	20	8	4
Number of alveoli (saccules) × 10⁶	30	112	129	257	280	—	300
Specific compliance: CL/FRC (mL/cm H2O/L)	0.04	0.038	—	—	0.06	—	0.05
Specific conductance of small airways (mL/sec/cm H2O/g)	0.02	—	3.1	1.7	0.12	8.2	13.4
Hematocrit	55 ± 7	37 ± 3	35 ± 2.5	40 ± 3	40 ± 2	42 ± 2	43-48
pHa	7.30 ± 7.40	—	7.35-7.45	—	—	—	7.35-7.45
PaCO2 (mm Hg)	30-35	—	30-40	—	—	—	30-40
PaO2 (mm Hg)	60-90	—	80-100	—	—	—	80-100

From O’Rourke PP, Crone RK: The respiratory system. In Gregory G (ed): Pediatric Anesthesia, 2nd ed. New York, Churchill Livingstone, 1989, p 63.

CL, compliance of lung; FRC, functional residual capacity.

Fluid requirements

Fasting Guidelines for Pediatric Patients

	Fasting Time (hr)
Age	Milk and Solids	Clear Liquids
<6 months	4	2
6-36 months	6	3
>36 months	8	3

Maintenance Requirements in Children

Weight (kg)	Fasting Time (hr) 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

Catheter sizes and their flow rates

		MEAN FLOW RATE RANGE (mL/min)
Catheter Size (gauge)	Length (inches)	Crystalloid (gravity)	Crystalloid (pressure)	Blood (pressure)
24	0.75	14 to 15	42 to 47	20 to 30
22	1	24 to 26	65 to 77	44 to 50
20	1.25 to 2	38 to 42	103 to 126	69 to 81
18	1.25 to 2	55 to 62	164 to 214	150 to 164
16	2	75 to 81	248 to 280	216 to 286
14	2	92 to 93	301 to 319	334 to 410
20	8	5	16	3
18	8	13	51	22
16	8	31	97	35
Data summarized from Hodge D III, Fleisher G: Pediatric catheter flow rates. Am J Emerg Med 3:403, 1985.

Paediatric Airway Equipments

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)

Laryngeal mask airway size characteristics

Laryngeal Mask Airway Size	Approximate Weight (kg)	Cuff Volume (mL)
1	<5	2 to 5
1.5	5 to 10	3 to 8
2	10 to 20	5 to 10
2.5	20 to 30	10 to 15
3	30 to 50	15 to 20
4	50 to 70	≤30
5	70 to 100	≤40
6	>100	≤50

Pediatric-sized laryngeal mask airways and compatible endotracheal tubes[*]

Laryngeal Mask Airway Size	Maximum Lubricated Uncuffed Standard Endotracheal Tube Inner Diameter (mm)	Maximum Lubricated Cuffed Standard Endotracheal Tube Inner Diameter (mm)	Maximum Flexible Bronchoscope Size[†]
1	3.5	3.0	2.7
1.5	4.0	4.0	3.0
2	5.0	4.5	3.5
2.5	6.0[‡]	5.0	4.0
3	—	6.0	5.0
4	—	6.0	5.0
5	—	7.0[†]	5.0
6	—	7.0[†]	5.0

Litman RS: The difficult pediatric airway. In Litman RS, editor: Pediatric anesthesia: The requisites, St. Louis, 2004, Mosby.

*Based on experiments performed by the author.

†As per LMA North America

‡Largest available uncuffed endotracheal tube available at The Children's Hospital of Philadelphia.

Laryngoscope blade types and sizes

	BLADE TYPE AND SIZE
Age	Miller	Wis-Hippel	Macintosh
Premature neonate	0	—	—
Term neonate	0 to 1	—	—
1 to 12 mo	1	1	—
1 to 2 yr	1	1.5	2
2 to 6 yr	2	—	2
6 to 12 yr	2	—	3

Endotracheal tube size[*]

Age	Weight (kg)	ID (mm)	Length (OT) (cm)	Length (NT) (cm)	Suction Catheter (F)
Premie	0.7 to 1.0	2.5	7 to 8	9	5
Premie	1.0 to 2.5	3.0	8 to 9	9 to 10	5
Newborn	2.5 to 3.5	3.5	9 to 10	11 to 12	6
3 mo	3.5 to 5.0	3.5	10 to 11	12	6
3 to 9 mo	5.0 to 8.0	3.5 to 4.0	11 to 12	13 to 14	6
9 to 18 mo	8.0 to 11.0	4.0 to 4.5	12 to 13	14 to 15	8
1.5 to 3 yr	11.0 to 15.0	4.5 to 5.0	12 to 14	16 to 17	8
4 to 5 yr	15.0 to 18.0	5.0 to 5.5	14 to 16	18 to 19	10
6 to 7 yr	19.0 to 23.0	5.5 to 6.0	16 to 18	19 to 20	10
8 to 10 yr	24.0 to 30.0	6.0 to 6.5	20 to 22	21 to 23	10
10 to 11 yr	30.0 to 35.0	6.0 to 6.5[†]	20 to 22	22 to 24	12
12 to 13 yr	35.0 to 40.0	6.5 to 7.0[*]	20 to 22	23 to 25	12
14 to 16 yr	45.0 to 55.0	7.0 to 7.5[*]	20 to 22	24 to 25	12

Data modified from Smith RM: Anesthesia for infants and children. CV Mosby, 1980, St. Louis; Davenport HT: Paediatric anaesthesia. Year Book Medical Publishers, 1973, Chicago.

ID, inner diameter; OT, orotracheal tube; NT, nasotracheal tube; F, French size (number is approximately equal to ID × 4).

*The endotracheal tube should fit so as to allow full normal expansion of both lungs with positive airway pressure but to permit a gas leak about the tube at 20 to 25 cm H2O.

† Cuffed tube

Recommended nasotracheal tube dimensions

	TUBE LENGTH (L) (cm)
Age (yr)	Tube Size (S) (ID, mm)	Yates et al. (1987)	Rees (1966)	Steward (1979)
0 to 3 mo	2.5 to 3.0	9.5 to 11.0	11.8	13.5
4 to 7 mo	3.5 to 4.0	12.5 to 14.0	13.6
1	4.0	14.0	14.5	15.0
2	4.5 15.5	15.2	16.0
3	4.5 to 5.0	15.5 to 17.0	15.6
4	5.0	17.0	16.5	17.0
5	5.0 to 5.5	17.0 to 18.5	16.8
6	5.5	18.5	17.1	19.0
7	5.5 to 6.0	18.5 to 20.0	17.8;
8	6.0	20.0	18.3	21.0
9	6.0 to 6.5	20.0 to 21.5	18.8
10	6.5	21.0	19.1	22.0
11	6.5 to 7.0	21.5 to 23.0	19.1
12	7.0	23.0		22.0

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
	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 /td>
	Solumedrol 1 mg/kg IV

Characteristics of volatile anesthetics

	MAC (%)
	Infant (1 to 6 mo)	Child (3 to 10 yr)	Adult
Halothane	1.1	0.9	0.7
Enflurane	––	––	1.6
Isoflurane	1.7	1.6	1.2
Desflurane	9.4	8.0	6.0
Sevoflurane	3.3	2.5	2.0

Adapted in part from Jones RM: Desflurane and sevoflurane; inhalation anesthetics for this decade? Br J Anaesth 65:527, 1990. Copyright © The Board of Management and Trustees of the British Journal of Anaesthesia. Reproduced by permission of Oxford University Press/British Journal of Anaesthesia.

Intravenous dosage of opioids in children

Drug	As Major Anesthetic	As Adjunct	As Postoperative Analgesic
Morphine	2 to 3 mg/kg	0.05 to 0.1 mg/kg per hr	0.05 to 0.1 mg/kg
Fentanyl	50 to 100 mcg/kg	1 to 3 mcg/kg per hr	1 to 2 mcg/kg
Sufentanil	10 to 15 mcg/kg	0.1 to 0.3 mcg/kg per hr	—
Alfentanil	150 to 200 mcg/kg	1 to 3 mcg/kg per min	—
Remifentanil	0.2 to 1.0 mcg/kg per min	0.1 to 0.4 mcg/kg per min	—
Hydromorphone	5 to 10 mcg/kg	3 to 5 mcg/kg per hr	3 to 5 mcg/kg

Intravenous doses of muscle relaxants in children

	MAINTENANCE			ED95 (mg/kg)
Drug	Intubation (mg/kg)	Bolus (mg/kg)	Continuous	Infusion (mcg/kg/m)	Infants Children
Mivacurium	0.2 to 0.3	0.1	10 to 20	0.1	0.1
Cisatracurium	0.15	0.1	1 to 5	0.05	0.05
Vecuronium	0.05 to 0.1	0.025	1	0.024	0.026
Rocuronium	0.8 to 1.0	0.3 to 0.5	15	0.2	0.3
Pancuronium	0.1	0.5	—	0.05	0.05
Pipecuronium	0.1	—	—	0.035	0.05

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Drug	Age Group	Dose (mg/kg)	Interval
Acetaminophen	Preterm Term	Load: 20; 15(PO), 20 (PR)	q12h
	>3 mo	Load: 20 to 30; 20 (PO)	q8h
		Load: 20 (PO); 15 (PO)	q4h
		40 (PR), 20 (PR)	q6h
Diclofenac	>1 yr	1 (PO)	q8h
Ibuprofen	>6 mo	10 to 15 (PO)	q6h
Ketorolac	>6 mo	0.25 to 0.5 (IM, IV)	q6h
Naproxen	>6 mo	5 to 10 (PO)	q8–12h
Celecoxib	>1 yr	1.5 to 3 (PO)	q12h

Opioid analgesics (μ-agonists)

Drug	Equipotent IV Dose (mg/kg)	IV:PO Equivalence	IV Dose (mg/kg)	PO Dose (mg/kg)	Interval (Minimum)	Comments
Codeine	1	1:1.5	NA	0.5-1.0	q3h	Usually prescribed with acetaminophen; limited analgesia in patients deficient in P450 2D6 isozyme
Fentanyl	0.001	1:10	0.001 to 0.002	Transmucosal: 200-mcg unit smallest available; titrate to effective dose	q1h (IV)	Chest wall rigidity associated with doses >0.005 mg/kg; also available as transdermal system (12.5 to 100 mcg/hr delivery) for chronic pain neuraxial
Hydromor-phone	0.02	1:5	0.015 to 0.02	0.1	q3h	May cause less itching and nausea; no active metabolites; good in renal failure; neuraxial
Meperidine	1.0	1:4	1.0	4	q3h	Avoid monoamine oxidase inhibitors; normeperidine (metabolite) causes seizures; only short-term use
Methadone	0.1	1:2	0.1 to 0.2 (load)	0.1 to 0.2	q12h	Very long-acting
Morphine	0.1	1:3	0.1	0.3	q3h	Histamine release; several slow-release oral forms available (MS Contin; Kadian; Avinza, Oramorph SR); neuraxial
Oxycodone	0.2			0.1 to 0.2	q3h	Little nausea or itch; slow-release oral form available (OxyContin); available in combination with acetaminophen or ibuprofen

Regional Anaesthesia

I. DOSES OF EPIDURAL ANALGESICS

Usual Doses and Infusion Regimens for Epidural Anesthesia in Pediatric Patients

Agent	Initial Dose	Continuous Infusion (Max. Doses)	Repeat Injections
Bupivacaine, levobupivacaine	Solution: 0.25% with 5 µg/mL (1/200,000) epinephrineDose:<20 kg: 0.75 mL/kg20-40 kg: 8-10 mL (or 0.1 mL/year/number of metameres)>40 kg: same as for adults	<4 mo: 0.2 mg/kg/hr (0.15 mL/kg/hr of a 0.125% solution or 0.3 mL/kg/hr of a 0.0625% solution)4-18 mo: 0.25 mg/kg/hr (0.2 mL/kg/hr of a 0.125% solution or 0.4 mL/kg/hr of a 0.0625% solution)>18 mo: 0.3-0.375 mg/kg/hr (0.3 mL/kg/hr of a 0.125% solution or 0.6 mL/kg/hr of a 0.0625% solution	0.1 to 0.3 mL/kg every 6-12 hr of a 0.25% or 0.125% solution (according to pain scores)
Ropivacaine	Solution: 0.2% Dose: same regimen in mL/kg as for bupivacaine (see above)	Same age-related infusion rates in mg/kg/hr as for bupivacaine (usual concentration of ropivacaine: 0.1%, 0.15%, or 0.2%) Do not infuse for more than 36 hr in infants < 3 mo	0.1 to 0.3 mL/kg every 6-12 hr of a 0.15% or 0.2% solution (according to pain scores)
Adjuvants	Avoid in infants < 6 moFentanyl (1-2 µg/kg) or sufentanil (0.1-0.6 µg/kg) or clonidine (1-2 µg/kg)	Select only one additive:Fentanyl: 1-2 µg/mL Sufentanil: 0.25-0.5 µg/mL Morphine: 10 µg/mL Hydromorphone: 1-3 µg/mL Clonidine 0.3 at 1 µg/mL of solution	Morphine (without preservatives): 25-30 µg/kg every 8 hr

Recommendations for dosing caudal and epidural blocks.

	Concentration	Dose	Possible Additives
Single-dose caudal	0.175% to 0.5%	0.75 to 1.25 mL/kg not to exceed 3 mng/kg	Epinephrine 2.5 to 5 mcg/mL
			Clonidine 1 to 2 mcg/kg
			Morphine 30 to 70 mcg/kg
Continuous caudal or lumbar epidural catheters	0.1% to 0.25%	0.4 mL/kg per hr or 0.2 to 0.4 mg/kg per hr	Fentanyl 2 to 5 mcg/mL
			Hydromorphone 5 to 10 mcg/mL
Continuous thoracic epidural	0.1% to 0.25%	0.3 mL/kg per hr or 0.1 to 0.2 mg/kg per hr	Fentanyl 2 to 5 mcg/mL
			Hydromorphone 5 to 10 mcg/mL

Bupivacaine, levobupivacaine, or ropivacaine may be used. Greater concentrations and larger doses should be reserved for levobupivacaine or ropivacaine. Doses and concentrations should be reduced in infants. Children less than 2 years of age who receive morphine centrally require 24-hour monitoring after its delivery

II. SPINAL ANAESTHESIA DOSES

Volumes of local anesthetic solutions for peripheral nerve blocks and regional anesthesia in children

Block	Volume (mL/kg)
Axillary	0.2 to 0.5
Interscalene	0.33
Sciatic	0.15 to 0.2
Femoral	0.5
Intravenous	0.5 to 10
Caudal	0.5 to 1.0
Intrapleural (infusion)	0.5 (per hr)

Usual Doses of Local Anesthetics for Spinal Anesthesia in Neonates and Former Preterm Neonates Younger than 60 Weeks of Preconceptual Age (up to a Weight of 5 kg)

Local Anesthetic	Dose (mg/kg)	Volume (mL/kg)	Duration (min)
Tetracaine 1%	0.4-1.0	0.04-0.1	60-75
Tetracaine 1% with epinephrine	0.4-1.0	0.04-0.1	90-120
Bupivacaine 0.5% isobaric or hyperbaric	0.5-1.0	0.1-0.2	65-75
Levobupivacaine 0.5%	0.1	0.2	75-88
Ropivacaine 0.5%	1.08	0.22	51-68

Usual Doses of Local Anesthetics for Spinal Anesthesia in Children and Adolescents

Local Anesthetic	Usual Dose(s)
0.5% Isobaric or hyperbaric bupivacaine	5 to 15 kg: 0.4 mg/kg (0.08 mL/kg) >15 kg: 0.3 mg/kg (0.06 mL/kg)
0.5% Isobaric or hyperbaric tetracaine	5 to 15 kg: 0.4 mg/kg (0.08 mL/kg) >15 kg: 0.3 mg/kg (0.06 mL/kg)
0.5% Isobaric levobupivacaine	5 to 15 kg: 0.4 mg/kg (0.08 mL/kg) 15-40 kg: 0.3 mg/kg (0.06 mL/kg) >40 kg: 0.25 mg/kg (0.05 mL/kg)
0.5% Isobaric ropivacaine	0.5 mg/kg (max 20 mg)

III. RECOMMENDATIONS FOR DOSING OF PERIPHERAL NERVE BLOCKS

Recommended Volumes of Local Anesthetic for Single-Shot Upper Limb Blocks with Neurostimulation by Patient Weight

	Patient Weight
Conduction Block	≤10 kg	11-30 kg	31-60 kg	>60 kg
Brachial plexus above clavicle	1 mL/kg	10 mL + 0.5 mL/kg above 10 kg	20 mL + 0.25 mL/kg above 30 kg	30 mL
Brachial plexus below clavicle	0.5 mL/kg	5 mL + 0.25 mL/kg above 10 kg	10 mL + 0.15 mL/kg above 30 kg	15 mL
Any nerve trunk at elbow	0.2 mL/kg	0.15 mL/kg	0.15 mL	10 mL
Any nerve trunk at wrist	0.05 mL/kg	0.05 mL/kg	0.05 mL/kg	3-5 mL

Recommended Volumes of Local Anesthetic for Single-Shot Lower Limb Blocks with Neurostimulation

Conduction Block	≤10 kg	11-30 kg	31-60 kg	>60 kg
Lumbar plexus (psoas compartment)	1 mL/kg	10 mL + 0.5 mL/kg above 10 kg	20 mL	20 mL
Femoral	0.5 mL/kg	5 mL + 0.35 mL/kg above 10 kg	12 mL + 0.3 mL/kg above 30 kg	25 mL
Fascia iliaca	1 mL/kg	10 mL + 0.5 mL/kg above 10 kg	20 mL + 0.25 mL/kg above 30 kg	30 mL
Proximal sciatic	1 mL/kg	10 mL + 0.5 mL/kg above 10 kg	20 mL + 0.3 mL/kg above 30 kg	30 mL
Sciatic in popliteal fossa	0.3 mL/kg	3 mL + 0.2 mL/kg above 10 kg	6 mL + 0.15 mL/kg	12.5 mL

Usual Local Anesthetic Infusion Rates with or without Bolus Doses of Either Ropivacaine 0.2%, Bupivacaine 0.125%, or Levobupivacaine 0.15% to 0.2% for Continuous Peripheral Nerve Blocks

Techniques	Plexus and Proximal Conduction Nerve Blocks *	Axillary and Popliteal Blocks
Infusion rate	0.2 mL/kg/hr up to 10 mL/hr	0.1 mL/kg/hr up to 5 mL/hr
Bolus doses	0.2 mL/kg up to 5 mL	0.1 mL/kg/hr up to 3 mL/hr
Maximum bolus doses per hour	3	3

Regional Technique	*Bolus Dose (mLμ/kg)[]**	Continuous Infusion (mLμ/kg per hr)
Axillary Parascalene	0.2 to 0.5 0.2 to 0.4	0.1 to 0.2 0.1 to 0.2
Femoral or lateral femoral cutaneous	0.3 to 1	0.15 to 0.3
Fascia iliaca	0.5 to 1	0.15 to 0.3
Lumbar plexus	0.5 to 1	0.15 to 0.3
Sciatic	0.3 to 1	0.15 to 0.3
Ilioinguinal/iliohypogastric	0.25	NA
Penile block	0.1	NA
Paravertebral	0.5	0.2 to 0.25

NA, not applicable.

Bupivacaine, levobupivacaine, or ropivacaine may be used. For bolus dosing, lower concentrations such as 0.2% to 0.25% should be used in infants and young children, whereas concentrations of 0.375% to 0.5% should be used in children >5 to 8 years of age. For continuous infusions, lower concentrations such as 0.1% to 0.2% of all agents are acceptable

References :

1.SMITH'S Anesthesia for Infants and Children, Seventh Edition.

2.Miller's Anesthesia - 7th ed.

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