**4. Anesthesia preparation in neonates before surgical procedure**

#### **4.1. Preoperative evaluation**

**3.1. Effects of anesthetic drugs and inhalation anesthetics on neonates**

bolic differences and, coexisting disease in neonatal patient population.

period [12, 22].

130 Selected Topics in Neonatal Care

• Decreased protein binding, • Increased organ blood flow,

• Higher metabolic rate.

neuromuscular blocker).

neonates [2, 4].

anesthetics are not preferred and/or not practices.

• Larger intravascular and extracellular fluid compartments,

• Immaturity of hepatic biotransformation pathways,

Effective and safe drug administration in neonates should be based on detailed knowledge on the physiological characteristics of the neonates and pharmacokinetics and pharmacodynamics of given drug. Clinical pharmacology in neonates is recognized with extensive variability. The effect of anesthetic agents varies with organ maturation, body water content and meta-

Inhalation anesthesia is a commonly used anesthetic technique in neonatal population. However, intravenous and regional anesthesia methods also can be applied as anesthetic technique in this patient population. The minimum alveolar concentration (MAC) of an inhaled anesthetic is the alveolar concentration that prevents movement in 50% of patients in response to a standardized stimulus (e.g., surgical incision) and changes with age [1, 6, 21]. MAC for inhalational agents is less in neonates than in infants (up to 6 months of age [12, 21]. In newborns, cardiac and respiratory functions and blood pressure are very sensitive to volatile anesthesia. Immature myocardium and less developed compensatory mechanisms are responsible for this result. Therefore, these anesthetics can cause dose dependent cardiac and respiratory depressant effect and can be seen bradycardia, hypotension and postoperative apnea. These effects are more pronounced during the induction

Intravenous anesthetic agents may be used for induction of anesthesia when inhalational

These factors mentioned above affect the properties of the intravenous anesthetics such as

An opioid agent causes fewer hemodynamic changes but it should be noted that increase the risk of postoperative apnea and late-onset re-sedation in recovery in preterm and term

Thus, it is crucial that intravenous lines are flushed and cleared of any medication (e.g. opioid,

Muscle relaxant may be required for some surgical procedures (especially abdominal surgical procedures such as necrotizing enterocolitis, abdominal wall defect). The response of neonates to nondepolarizing muscle relaxant is quite variable. Neuromuscular junction is immature in preterms and this increases the susceptibility to muscle relaxants. However, the large

duration of effect (onset and termination), doses and toxicity limits of drugs.

Factors affecting the administration of intravenous anesthesia can be listed as follows:

Anesthetic management in neonatal patients can be challenging but careful preoperative assessment means that a safe and smooth preparation process for the neonates and anesthetic team. This evaluation is also an approach that encourages confidence for their parents.

A careful preoperative examination allows the anesthetist to determine the risk of anesthesia based on the general state of health of newborn. It is aimed to establish an appropriate plan for anesthesia, postoperative care and analgesia in the light of acquired information.

Preoperative assessment in neonates should include a comprehensive examination of the neonate's perinatal history (such as prematurity, apnea-hypoxic episode history, duration of oxygen dependency, neurological damage etc.), congenital anomalies, previous anesthesia applications, and general state of health (acute, chronic lung disease, cardiac pathologies, etc.) [23].

Premature, ex-premature and term neonates are highly heterogeneous group within newborn period and needs various surgical interventions. Most of them come directly from the neonatal intensive care unit (NICU) and require urgent intervention. Many unusual congenital syndromes occur in childhood. These congenital anomalies in newborn period may accompany emergency surgical procedures [24]. Congenital anomalies that may cause difficult intubation should be noted and the anesthesia plan should be made accordingly.

In addition, a more detailed examination should be performed to reveal early postnatal problems that may be seen (such as hypoglycemia, infection and sepsis, etc.).

Risk factors which are important in neonatal anesthesia are summarized in **Table 2**.

A systematic approach to preoperative evaluation will prevent important problems from being overlooked. Many healthy neonates undergoing elective simple surgery and procedures are fit and do not require compressive physical examination. However, evaluation of the head and neck (such micrognathia, limited neck mobility, macroglossia, etc.) and cardiorespiratory examination (cardiac congenital anomalies, breathing sounds, respiratory pathologies associated with increased secretion and inflammation etc.) should be performed before surgical procedures. Also in cardiac examination, previously undiagnosed murmur with pathological qualities (e.g. loud, continuous, diastolic and or/associated with a trill) may be noticeable.

Evaluation of the airway is critical to the delivery of safe anesthesia. In neonates with a syndrome associated with airway anomalies, the potential presence of a difficult airway (**Table 2**) (*e.g. Pierre-Robin, Goldenhar, Treacher-Collins Syndrome, cleft palate and lip, maxilla mandibular synechia, etc.*) can be identified preoperatively.

It is also important to identify any concomitant (such as necrotizing enterocolitis, hyaline membrane syndrome, cardiac pathologies, sepsis, etc.) disease which might increase the risk of anesthesia and surgery. Familial, genetic, and neuromuscular diseases are important for anesthetic management. The presence of these diseases should be questioned.

**4.2. Preparation of the operating theater**

• Humidify and warm inspired anesthetic gases

• Using heating solution for cleansing the skin

• Transport the neonate in a heated incubator

Gas resources and suction materials must be checked.

**4.3. Assessment of patient and anesthetic equipment**

padding, rolls and tapes can be used safely for the position.

• Warm blood and intravenous solutions

of the goals of the preoperative visit.

of cyanosis, vomiting and secretions.

*4.3.1. Airway*

the patient's position.

to reduce heat loss:

tress, clear plastic drapes

Anesthesia preparation should be based on the information obtained from the preoperative visit. But, anesthesia preparation does not include preparation of anesthetic equipment, drugs and anesthesia station only. It also includes preparations for the operating theater, such as proper heating of the surgery room, preparations for aspiration materials and arrangements for

Neonatal Care for Anesthesiologists http://dx.doi.org/10.5772/intechopen.71952 133

The newborn baby has a high ratio surface area to body weight and a thin layer subcutaneous fat tissue. Therefore, neonates lose heat rapidly more than older children and adult [1]. The operating room temperature must be set to maintained neonate's thermoneutral temperature in order to minimize heat loss. In addition, the following applications can be used

• Many devices such as warmed blanket, overhead radiant heater, a forced air warmer mat-

The patient position is one of the issues to be considered. Different materials such as soft foam

Proper anesthesia preparation is very important for safe anesthetic management. This is one

No matter what anesthetic method is used (sedation or general anesthesia), the airway must be guaranteed in every situation. Difficult, immature airway and respiratory system can lead to airway obstruction during sedation or mask ventilation. Therefore, appropriately size face mask, oropharyngeal airway, laryngoscope blades, endotracheal tube and suction catheters must be available. The use of transparent face masks are recommended for early recognition

Endotracheal Intubation Study Group [26] demonstrated that the use of Microcuffed tracheal tubes is effective and safe in neonates and young children. But, most anesthetist prefer to use

The laryngeal mask airway (LMA) can be used as an alternative to endotracheal intubation in the presence of difficult airway and for some short surgical procedures. Against possibility of

according to the clinical condition of the patient rather than routine.

Body weight, height, head circumference size must be recorded in order to evaluate newborn's physical status. For example, microcephaly is associated with some genetic disorders and may cause neurological sequel, which may pose a risk for anesthesia.

In laboratory evaluation, a baseline hemoglobin measurement should be obtained for minor surgical procedures [24]. If there is no indication for emergency surgery, anemia should be treated before surgical procedure. Because, even if it is a minor surgery, anemia may precipitate postoperative apnea and bradycardia in neonate. In addition to hemoglobin, in infants with fluid and electrolyte deficit, initial electrolyte values are also important. In major surgeries (e.g. oesophageal atresia, necrotizing enterocolitis, congenital cardiac surgery, neurosurgery) full blood count, blood electrolyte values, renal function and clotting test are recommended [25].

Fasting time before elective surgery should be pointed out. Clear liquid, breast milk and formula milk intake should be prohibited at according to the recommended fasting times (2 hours for clear liquids, 4 hours for breast milk, 6 hours for formula/non-human milk) before elective surgery [12, 14, 25]. Since prolonged period of fasting time pose a risk for hypoglycemia and dehydration, dextrose containing intravenous maintenance fluids should be instituted early period.

A systematic approach the preoperative assessment is summarized in **Table 3**.


**Table 3.** Systematic approach to preoperative assessment.

#### **4.2. Preparation of the operating theater**

It is also important to identify any concomitant (such as necrotizing enterocolitis, hyaline membrane syndrome, cardiac pathologies, sepsis, etc.) disease which might increase the risk of anesthesia and surgery. Familial, genetic, and neuromuscular diseases are important for

Body weight, height, head circumference size must be recorded in order to evaluate newborn's physical status. For example, microcephaly is associated with some genetic disorders

In laboratory evaluation, a baseline hemoglobin measurement should be obtained for minor surgical procedures [24]. If there is no indication for emergency surgery, anemia should be treated before surgical procedure. Because, even if it is a minor surgery, anemia may precipitate postoperative apnea and bradycardia in neonate. In addition to hemoglobin, in infants with fluid and electrolyte deficit, initial electrolyte values are also important. In major surgeries (e.g. oesophageal atresia, necrotizing enterocolitis, congenital cardiac surgery, neurosurgery) full blood count, blood electrolyte values, renal function and clotting test are recommended [25]. Fasting time before elective surgery should be pointed out. Clear liquid, breast milk and formula milk intake should be prohibited at according to the recommended fasting times (2 hours for clear liquids, 4 hours for breast milk, 6 hours for formula/non-human milk) before elective surgery [12, 14, 25]. Since prolonged period of fasting time pose a risk for hypoglycemia and dehydration, dextrose containing intravenous maintenance fluids should be insti-

anesthetic management. The presence of these diseases should be questioned.

and may cause neurological sequel, which may pose a risk for anesthesia.

A systematic approach the preoperative assessment is summarized in **Table 3**.

Medical conditions (co-morbidities, congenital syndromes, genetic disease)

Airway (especially pathologies that can cause difficult intubation, micrognathia)

Neurological (intracranial hemorrhage history-treatment, seizure activation)

**Table 3.** Systematic approach to preoperative assessment.

tuted early period.

132 Selected Topics in Neonatal Care

*History of neonate* Perinatal

Medications

 Body weight, height Physical observation

 Bronchopulmonary dysplasia Laryngeal pathologies, stridor

Previous resuscitation history Previous anesthesia experience Optimize medical condition Determination of anesthesia risk Determination of anesthetic plan

*Respiratory System* Prematurity

 Breathing sounds *Cardiovascular system* Auscultation of heart

*Examination*

*Gathering of patient information*

Previous anesthesia and surgical experience

Anesthesia preparation should be based on the information obtained from the preoperative visit. But, anesthesia preparation does not include preparation of anesthetic equipment, drugs and anesthesia station only. It also includes preparations for the operating theater, such as proper heating of the surgery room, preparations for aspiration materials and arrangements for the patient's position.

The newborn baby has a high ratio surface area to body weight and a thin layer subcutaneous fat tissue. Therefore, neonates lose heat rapidly more than older children and adult [1]. The operating room temperature must be set to maintained neonate's thermoneutral temperature in order to minimize heat loss. In addition, the following applications can be used to reduce heat loss:


Gas resources and suction materials must be checked.

The patient position is one of the issues to be considered. Different materials such as soft foam padding, rolls and tapes can be used safely for the position.

#### **4.3. Assessment of patient and anesthetic equipment**

Proper anesthesia preparation is very important for safe anesthetic management. This is one of the goals of the preoperative visit.

#### *4.3.1. Airway*

No matter what anesthetic method is used (sedation or general anesthesia), the airway must be guaranteed in every situation. Difficult, immature airway and respiratory system can lead to airway obstruction during sedation or mask ventilation. Therefore, appropriately size face mask, oropharyngeal airway, laryngoscope blades, endotracheal tube and suction catheters must be available. The use of transparent face masks are recommended for early recognition of cyanosis, vomiting and secretions.

Endotracheal Intubation Study Group [26] demonstrated that the use of Microcuffed tracheal tubes is effective and safe in neonates and young children. But, most anesthetist prefer to use according to the clinical condition of the patient rather than routine.

The laryngeal mask airway (LMA) can be used as an alternative to endotracheal intubation in the presence of difficult airway and for some short surgical procedures. Against possibility of difficult pediatric airway, advanced airway devices (such as Glidescope, Airtraq) which allow indirect visualization of the larynx should be available [27].

In addition to routine monitoring, direct observation of the neonate is also an important monitoring method. This observation allows the anesthetist to recognize early signs of certain

Neonatal Care for Anesthesiologists http://dx.doi.org/10.5772/intechopen.71952 135

Inhalation agents or intravenous anesthetics may be used for induction of anesthesia. Although depending on the choice of anesthetist, induction with inhalation anesthetics is a more preferred method. One of the characteristics of the newborns that are different from older children and adults is that they have relatively high alveolar ventilation but low functional residual capacity [6, 14, 24]. This higher minute ventilation to FRC ratio with relatively higher blood flow to vessel rich organs contributes to a rapid increase in alveolar anesthetic concentration*.* These features enable rapid induction and rapid recovery in gen-

Inhalational induction has the advantage of protection of spontaneous ventilation (especially,

With the advantages we have mentioned above, volatile anesthetics cause dose dependent cardiac and respiratory depressant effect in neonates. These effects can result bradycardia, hypotension and postoperative apnea. This hypotensive effect is also more pronounced in

Also, immature airway and respiratory system may cause airway obstruction in mask ventilation during induction phase. Laryngospasm is a frequent occurrence in neonatal anesthesia in this period [31] and if it is intervened early is usually easy to manage. However, laryngospasm, hypoventilation, hypoxia are among the causes of apnea during induction (especially

In short surgical procedures, mask ventilation or laryngeal mask airway may be suitable to support respiration. However, endotracheal intubation is frequently performed in patients with emergency surgical procedures, long and major surgical interventions, conditions that

In situation that where inhalation anesthetics are contraindicated or not preferred, intrave-

As we have already mentioned, total body water and extracellular fluid are increased in neonates [16]. These different fluid component affect volumes of distribution of intravenous anesthetic drugs (this means increasing the volume of distribution, especially for water-soluble

In addition, due to the immaturity of hepatic functions, duration of action will be prolonged

Muscle relaxant may be required for some neonatal surgical procedures. However, due to immaturity of the neuromuscular junction, neonates have an increased sensitivity to the effects of nondepolarizing neuromuscular blocking drugs [33]. For this reason, prolonged

neonates and preterms with cardiovascular instability than older children.

clinic situations (such as cyanosis and pallor).

important in neonates with potentially difficult airway).

requiring muscle relaxation and aspiration risk.

nous anesthetics may be used to induce and maintain anesthesia.

in neonates if the drug depends on hepatic metabolism [6].

effects may occur at additional doses.

eral anesthesia [6].

in cases of late notice) [32].

drugs).

#### *4.3.2. Anesthesia devices*

The anesthesia device must be pre-checked before surgical procedure and anesthesia practice. It is essential that the anesthesia ventilator has the ability to provide neonatal compliance, small tidal volume *(*usually in pressure controlled ventilator mode) and positive end-expiratory pressure [24]. In recent years, new generation anesthesia machines have been developed which is able to small tidal volumes [28] and to provide the ability to ventilate using pressure support ventilation (PSV) [29].

#### *4.3.3. Monitoring*

Heart rate-electrocardiography, non-invasive blood pressure, pulse oximetry, and temperature monitorizations are sufficient for basic monitorizations in a healthy newborn.

In neonates whom more risky for surgical procedures, in major surgical procedures and a special circumstances (such as congenital cardiac surgery, oesophageal atresia, congenital diaphragmatic hernia, expected ventilation-perfusion anomalies, hemodynamic changes, and acid-base imbalance), invasive arterial blood pressure and central venous pressure should be monitored.

Two oxygen saturation probes (the right arm probe – pre ductal, the leg probe - post ductal) must be plugged. This approach may provide the diagnosis as, with reverting to transitional circulation and is important to evaluate possible PDA mediated shunt development.

In last three decades, continuous monitoring of respiratory gases (inspiratory oxygen and expiratory end-tidal carbon dioxide and monitoring of gas flows) and continuous use of ventilator disconnection devices are observed routinely in most anesthesia clinic [27].

The precordial oesophageal stethoscope is a traditional and still valid method of monitoring the newborn. With this method, changes in heart rate and respiratory parameters can be identified in early phase.
