ANATOMICAL AND PHYSIOLOGICAL DIFFERENCES IN A YOUNG CHILD

The anatomical and physiological differences of a child, especially a neonate, mean that anaesthesia of a paediatric patient requires special qualifications and experience, and for anaesthesiologists who do not work with children on a daily basis, it is a real challenge. They cause slightly different reactions of children to anaesthesia than observed in adults and – as mentioned – constitute risk factors for the development of both respiratory and cardiovascular complications.

Adaptation to postnatal life is a period of enormous transformations in the human body, and any medical intervention during this time creates a significant risk of disturbing the fragile systemic homeostasis. Elective surgeries – other than those resulting from the need to correct congenital defects – should not be performed on children before they reach 46–48 weeks of age, counting from conception [7].

NEUROTOXICITY OF GENERAL ANAESTHETICS

For over two decades, there has been an ongoing discussion among anaesthesiologists (especially those who deal with paediatric anaesthesia on a daily basis) about the potentially neurotoxic effects of anaesthetics on the immature, developing central nervous system (CNS) of young children. The basis for these considerations were the results of preclinical studies published by Jevtovic-Todorovic et al. [14], regarding the influence on cognitive functions of drugs used in general anaesthesia administered to rodents in the neonatal period. The results of studies conducted and published by this and other teams on the influence of ketamine, benzodiazepines, barbiturates, propofol, and finally inhalation anaesthetics, including isoflurane, on the immature brain of representatives of various animal species, including primates, in the vast majority of cases proved their strong neurodegenerative effect, mainly in the mechanism of significant intensification of apoptosis [15–17].

The medical literature on laboratory tests provides ample evidence supporting the thesis of the neurotoxic and neurodegenerative effects of anaesthetics on the immature brain. The problem is that these findings are not sufficiently reflected in clinical trials. Available cohort studies do not allow for definitive conclusions. Some of the results confirm that a single exposure to anaesthetics during the period of the greatest risk of their potential neurotoxic effects on the maturing CNS of a child should not cause permanent cognitive or behavioural disorders. However, repeated exposure (during several consecutive surgical procedures) significantly increases the likelihood of such disorders [18–21].

The results of a multicentre, prospective, randomized study (with the working title GAS study – general anaesthesia and awake-regional anaesthesia in infancy), which compared the influence of two methods of anaesthesia: general and regional (spinal) in infants operated on in the first 3 months of life due to inguinal hernia on the IQ of these children measured with a special test at the age of 5, showed that the obtained results did not differ significantly between the two groups of study subjects. This allowed for the conclusion that a single exposure of a child to general anaesthetics during surgery lasting up to one hour does not affect their behavioural and cognitive functions assessed both at the age of 2 and 5 [22].

Due to the lack of clear results of clinical trials and alarming laboratory test results, the Paediatric Section of the PTAiIT, similarly to the US Food and Drug Administration (FDA) and the European Society for Paediatric Anaesthesiology (ESPA), maintains its position formulated for the first time in 2012 and recommends extreme caution in qualifying the youngest children, under 3 years of age, for elective procedures (which can be performed without harm to the patient’s health at a later age) under general anaesthesia [13, 23–26].

EQUIPMENT IN THE OPERATING ROOM, ANAESTHESIA STATION, ANAESTHESIA TABLE, AND POST-ANAESTHESIA CARE ROOM

The age and body mass of the child undergoing anaesthesia influence the preparation process and determine the type of equipment that must be provided in the operating room, the anaesthesia station, and the post-anaesthesia care room.

Children should not stay in rooms intended for adult patients. A hospital where children are treated, anaesthetized, and operated on must have separate rooms designated just for them. The interior design of the rooms should meet the age-specific emotional and aesthetic needs of patients. In a hospital where procedures are performed for adult and paediatric patients, the procedure plan should additionally include the principle of time or space allocation of procedures for these groups of patients [12].

ANAESTHESIOLOGY TEAM

According to §11 of the Regulation of the Minister of Health of 16 December 2016 (as amended), “anaesthesia of a neonate or an infant may be performed by a specialist in anaesthesiology and intensive care or an anaesthesiologist with the written consent of the physician in charge of the anaesthesiology and intensive care department, an anaesthesiology department, a paediatric anaesthesiology and intensive care department or a paediatric anaesthesiology department, as well as by a physician undergoing specialization under the direct supervision of an anaesthesiology and intensive care specialist” [28].

According to anaesthesiology and intensive care specialists from the Paediatric Section of the PTAiIT, children under 3 years of age should be anaesthetized by a specialist in anaesthesiology and intensive care specialist with knowledge and experience in the management of patients in this age group. This is consistent with the opinion of the ESPA and confirmed by available research (APRICOT) [1].

The anaesthesiologist must be accompanied by an anaesthetic nurse with knowledge and experience in the care of children under 3 years of age.

PREPARING CHILDREN FOR ANAESTHESIA

In accordance with the aforementioned regulation of the Minister of Health [28], a specialist in anaesthesiology and intensive care or an anaesthesiologist or a physician in the process of specialization is obliged to take patient’s medical history and perform physical examination of the child at least 24 hours before the elective surgery in order to qualify the patient for anaesthesia. According to the latest regulations, it is advisable to establish an anaesthesiology clinic at the hospital, which would provide convenient and comfortable conditions for obtaining medical history and performing physical examinations, preferably in a special room adapted to different age groups of children. Such a room allows for privacy while taking medical history or examining a patient.

The main goal during anaesthesiology qualification is to select the anaesthetic method that will optimally ensure the patient’s safety during anaesthesia, which is in line with DeHaBePA signed by the PTAiIT on 13 June 2010 [6]. To ensure safe anaesthesia, it is necessary to review the patient’s current records, containing information about their health, as well as other documents, especially those relating to previous hospitalizations, procedures and anaesthesia, or comorbidities.

During an anaesthesiology consultation, special attention should be paid to the following issues:

A history of infectious diseases within the 2 weeks preceding anaesthesia excludes the possibility of performing the procedure as elective due to the increased risk of intra- and postoperative complications. It should be remembered that after an infection, bronchial hypersensitivity may persist for up to 6 weeks, and in the case of children, it may also increase the risk of respiratory complications, which in certain cases may be an indication for postponing the procedure for at least 2 weeks after the acute symptoms have subsided.

Infection-related criteria for disqualification from elective anaesthesia include: acute inflammation of the upper and/or lower respiratory tract (red throat, runny nose, productive cough, increased body temperature (> 37.8°C), auscultatory changes over the lungs), antibiotic therapy (related to respiratory tract infection) up to 2 weeks after the end of treatment, infectious diseases.

Selected infectious diseases and the period during which a patient cannot receive elective anaesthesia are presented below:

In the case of respiratory syncytial virus (RSV) infection, the time from the end of the disease must be 4–6 weeks.

COMORBIDITIES

Systemic diseases that can significantly impact planned anaesthesia include neuromuscular diseases (e.g., muscular dystrophies), malignant hyperthermia during a previous anaesthesia or a family history of malignant hyperthermia, congenital coagulation disorders, congenital heart defects, and defects and diseases of other organs and systems. Children with asthma are always at risk of perioperative complications, which may be related, for example, to bronchospasm. To ensure safe anaesthesia in this group of patients, their condition must be optimized.

The following situations are important for the safety of anaesthesia:

ADDITIONAL TESTS

Before administering anaesthesia and the surgery, the anaesthesiologist must review the results of laboratory and imaging tests, the scope of which depends on the type and extent of the surgery.

Generally, in children with a score of I or II according to the American Society of Anesthesiologists (ASA) classification system, qualified for day surgery procedures and not at high risk of bleeding, only a complete blood count is recommended (although the necessity of this test is questioned in some European countries).

In a child with an ASA score of at least III or if the procedure involves the loss of a large volume of blood, the following are necessary:

The performance of other tests [electrocardiography – ECG, echocardiography – ECHO, X-ray, computed tomography – CT, magnetic resonance imaging – MRI] should depend on comorbidities, the patient’s general condition, and the type and scope of surgery.

In children in good general condition and free from comorbidities (including oncological diseases), it is possible to accept tests performed 3 months before anaesthesia, provided that the child’s condition has not changed significantly since the tests were performed and the results of these tests were normal.

Deviations from the norm in laboratory tests that disqualify from elective surgery include:

According to the latest recommendations, in the absence of active bleeding, the platelet count should not be lower than: 50 G L^–1 before a planned major surgery, 20 G L^–1 before central venous catheter insertion, and 50 G L^–1 before liver biopsy. A platelet count below 80 G L^–1 is an indication for preoperative diagnosis.

It is recommended to implement compensatory treatment if the values of prothrombin time (PT), international normalized ratio (INR) and activated partial thromboplastin time (aPTT) exceed at least twice the reference values (for individual age groups) [31, 32]:

NOTE! In premature infants and small for gestational age (SGA) infants, the upper normal limit of aPTT may reach 95 and 77 s, respectively.

MEDICATION

The anaesthesiologist must be familiar with the medications taken by the patient and make modifications to the pharmacotherapy if a given medication may affect the patient’s safety. It is important to note that there are few medications that should be discontinued before or on the day of surgery. Among those that definitely should not be discontinued are antiepileptic medications. The examples given below use principles analogous to those used in the 2022 guidelines for anaesthesia in adults according to the European Society of Cardiology (ESC) – cardiovascular risk assessment and management in patients undergoing non-cardiac surgery [33].

ADDITIONAL TESTS AND CONSULTATIONS BEFORE SURGERY

After reviewing the information in the questionnaire and the patient’s medical history, the anaesthesiologist may decide whether additional tests and/or specialist consultations are necessary.

During the visit, the anaesthesiologist is also required to conduct a physical examination, the scope of which depends on the anamnesis obtained from the parents or, in the case of older patients, also from them. Particular attention should be paid to the assessment of the nose, mouth and anatomical abnormalities; auscultation of the chest (heart, lungs) should be performed and any difficulties with intubation should be assessed [34].

PREMEDICATION

The final element of preparing a child for anaesthesia is planning premedication before the procedure, which largely depends not only on the patient’s age but also on their psychoemotional state. The aim of this action is to reduce anxiety and calm the patient, as well as to provide pain relief if the child reports such complaints or if analgesia is planned in advance.

Table 3 presents the drugs most commonly used in premedication along with their dosage and possible route of administration.

In recent years, there has been a trend to avoid the use of benzodiazepines during premedication due to the unintended reverse effect, leading to irritation and agitation in children, as well as a higher risk of neurotoxicity, especially in infants and young children up to 4 years of age, during the maturation of the CNS. α₂-receptor agonists, through their physiological action, stimulate sedation and sleep in a mechanism similar to the natural one by inhibiting receptors in the locus oeruleus in the brain. The modification of this procedure in recent years has been influenced by the increase in the number of diagnoses of disorders such as attention deficit hyperactivity disorder (ADHD), attention deficit disorder (ADD), autism spectrum disorder, Asperger syndrome, and others in children and adolescents. Non-pharmacological methods using distractors are increasingly recommended. They include mirror techniques, virtual animation, systemic desensitization, behavioural training, virtual reality glasses (VR), etc., which, through preoperative preparation and/or distraction and reduction of intraoperative anxiety, allow for the reduction or even avoidance of drug administration.

CONSENT TO ANAESTHESIA

The anaesthesiology visit ends with obtaining written informed consent for anaesthesia, after presenting the type of anaesthesia (general/regional/ procedural sedation and analgesia) and answering questions about the procedure. Consent is given by parents or legal guardians; in the absence of such, consent is given by the family court.

FASTING TIME

The current rules for food withdrawal in the paediatric population prior to elective anaesthesia include the following restrictions [35]. The following should be discontinued:

ANAESTHESIA IN A CHILD WITH A FULL STOMACH

Anaesthesia in a child with a full stomach increases the risk of complications due to the risk of aspiration of food into the respiratory tract. Conditions associated with the risk of aspiration and a full stomach are presented in Table 4.

Currently, it is recommended, whenever possible, to perform ultrasound assessment of gastric contents [36].

When inducing anaesthesia in a young child with a full stomach, intravenous access should always be established before induction, and if unsuccessful, intraosseous access should be performed. Alternatively, in a neonate in the first few hours of life, umbilical vein access can be established. The presence of intravascular or intraosseous access allows for the induction of anaesthesia by a controlled rapid induction method, i.e. with ventilation before intubation. Ventilation before intubation is necessary because the younger the child, the higher the metabolism and therefore the oxygen demand, and at the same time the smaller FRC volume, which makes it difficult to “store” oxygen, so if the child is not oxygenated very quickly, desaturation occurs. Traditional rapid sequence induction (RSI), i.e., passive preoxygenation, followed by rapid administration of a sedative and succinylcholine (suxamethonium) (the fastest and shortest-acting muscle relaxant), followed by intubation without mask ventilation, is contraindicated in the youngest children. Apnoea, even after prior oxygenation, is tolerated for a very short time, and intubation may be more difficult than in older children. Ventilation with low pressures and tidal volumes through a face mask with the option of positive inhalation pressure (PIP) of up to 15 mmHg and the fraction of inspired oxygen (FiO₂) of 0.8, has been shown not to increase the risk of aspiration and significantly improves patient safety. In this age group, continued oxygenation during intubation is recommended, as is possible with some video laryngoscopes, or via a cannula placed in the nasopharynx.

To visualize the larynx, a laryngoscope and a spatula (straight vs. curved) should be used, choosing those tools with which the anaesthesiologist has the most experience. If the anaesthesiologist is proficient in using a video laryngoscope and it is available in the appropriate size, it is recommended that it be used as the equipment of choice.

The anaesthetic of choice in a haemodynamically stable patient is propofol (in neonates it is used off-label, thiopental can be used on-label), and in neonates and children in shock and/or hypovolemia – ketamine.

An opioid, typically fentanyl, is also commonly used. However, it should be noted that its administration may result in vomiting. Rocuronium is most often used to provide muscle relaxation, necessary for efficient and non-traumatic intubation. Its advantage – apart from the rapid onset of action, comparable to that of succinylcholine – is the possibility of immediate reversal of the effect using sugammadex. Due to their longer duration of action in neonates, atracurium or cisatracurium, whose metabolism is not dependent on renal and hepatic function, are often used in this age group.

Cricoid cartilage compression is not recommended; this maneuver (Sellick maneuver) has not been proven to be effective in preventing regurgitation, but it often causes problems with ventilation or intubation.

There is no clear indication of when a gastric tube should be inserted, or whether, if one is already in place, it should be left during induction or removed. Therefore, the decision in this matter depends on the anaesthesiologist’s experience. In all cases, induction in a young child on a full stomach should be performed by an experienced anaesthesiologist or at least he/she should be present in the room, ready to assist immediately. The choice of ETT depends on the anaesthesiologist’s experience and available equipment. In the past, uncuffed ETTs were used in the youngest children, even in patients with a full stomach – if the tube was properly selected, this did not increase the risk of aspiration. Currently available ETTs with a micro-cuff (low-pressure cuff ) enable intubation of even full-term neonates with this type of tube. Using cuffed tubes reduces the need for reintubation, which increases the safety of anaesthesia in children with a full stomach. It should be remembered to choose a tube half a size smaller than the size without the cuff. It is advisable to use a guide to avoid tube manipulation and reduce intubation time [37, 38].

OPERATION PLAN

The order of operations performed in the operating room and procedures requiring anaesthesia performed outside the operating room should take into account the age of the patients undergoing surgery. The smaller the child, the sooner they should be anaesthetized and operated on to reduce the risk of dehydration and possible hypoglycaemia. If the procedure is delayed, the child should be given a clear fluid or an IV drip (10 mL kg^–1 of a balanced solution). When planning a surgical procedure, consideration should be given to the possibility of transferring the child to a paediatric intensive care unit (PICU) in the immediate postoperative period. This applies particularly to neonates and children undergoing surgery in critical condition.

METHODS OF INDUCTION OF ANAESTHESIA

There are the following methods of induction of anaesthesia:

ENDOTRACHEAL INTUBATION

Before performing endotracheal intubation, it is necessary to determine that the child is unconscious and adequately oxygenated. When oxygenating neonates and premature infants, 100% oxygen should be administered with caution due to its toxic effects in this group of patients.

It is believed that endotracheal intubation in children should be performed, whenever possible, after administration of a nondepolarizing agent. Modern nondepolarizing agents act rapidly with minimal risk of electrolyte and circulatory disturbances.

Succinylcholine should only be used in exceptional situations, such as when a patient is anaesthetized on a full stomach or when difficult intubation is anticipated.

This medication should not be used in boys under two years of age due to the risk of asymptomatic muscular dystrophy, such as Duchenne muscular dystrophy (DMD). Particular sensitivity to succinylcholine, manifested by the development of defibrillation- resistant ventricular fibrillation, occurs in these children much earlier than the first symptoms of this disease.

It is also possible to intubate a child without muscle relaxation, but always under deep sedation and with sufficient analgesia.

Over the past decade or so, new devices have been introduced into widespread use, allowing the development of methods that increase the effectiveness and safety of intubation in both normal and problematic airways. The Pediatric Difficult Intubation Registry (PeDIR) has also been established and its reports are available [42–44].

Many scientific papers, prospective studies, and guidelines of scientific societies regarding the improvement of the quality of management in the case of difficult airways have also been published [45–48].

ASSESSMENT OF INTUBATION DIFFICULTY

Before administering anaesthesia, it is essential to examine the child and assess the degree of difficulty maintaining a patent airway. Neonates and infants constitute a vulnerable group, with an increased risk of complications and a lower degree of predictability of problematic airways. The rate of difficult intubation in this group is 5.8%, compared with 0.88% in the overall paediatric population; 9% of these children also experience difficulties with face mask ventilation [1, 2, 49, 50].

The Colorado Pediatric Airway Score (COPURway Score) incorporates medical history, bedside testing, and anthropometric measurements and suggests appropriate intubation equipment. It combines elements of the Mallampati and Cormack Lehane scales [51] (Table 6A, B).

CONTINUOUS OXYGENATION DURING APNOEA

Traditional pre-oxygenation using a face mask is difficult to perform in children due to the lack of cooperation and anxiety. The term “preoxygenation” means the continuous supply of oxygen during induction of anaesthesia and intubation, both in the period of active breathing and apnoea, until the airway is effectively secured. This procedure reduces the risk of desaturation and extends the time of “safe apnoea”, defined as the time of maintaining saturation above 90% [48, 52, 53]. Continuous oxygenation during apnoea contributes to higher first-attempt intubation success and reduces the number of intubation attempts by extending the time available for the procedure [46, 47]. This technique is particularly important in patients in whom face mask ventilation should be avoided after induction of anaesthesia and in patients at increased risk of hypoxemia.

The techniques used during apnoeic oxygenation are presented in Table 7 [48, 53].

DEVICES THAT INCREASE THE EFFECTIVENESS AND SAFETY OF INTUBATION

Devices that increase the effectiveness and safety of intubation include:

NEW INTUBATION STRATEGIES

The use of a video laryngoscope with an age-appropriate standard blade (Macintosh or Miller) is recommended as the first-line method for tracheal intubation in neonates and infants, including lateral decubitus intubation [46, 48].

Repeated intubation attempts using the same device should be avoided as this increases the number of complications [45, 46].

According to some authors, videolaryngoscopy with high-flow oxygen supplementation should be the standard of care for tracheal intubation in neonates, infants, and children [54].

An equally effective method is intubation using a bronchofiberoscope, which remains the “gold standard” for patients with limited mouth opening and symptoms of cervical spine instability [55]. However, it is necessary to be well trained and gain experience in using this method, as it may take too much time.

HYBRID TECHNIQUES

Combining techniques takes advantage of the strengths of the devices, particularly video laryngoscopy and fiberoscopy. Hybrid techniques require the collaboration of two physicians – one responsible for visualizing the larynx using the video laryngoscope, and the other who inserts the fiberscope into the airway. This approach allows visualization throughout the intubation period [56].

In the case of difficult airways, another hybrid technique can also be used, which involves securing ventilation with a laryngeal mask during the initial period and then inserting an ETT through the mask channel using a bronchofiberscope [45, 47].

LARYNGEAL MASK AIRWAYS

Among many supraglottic devices, LMAs have found a permanent place in paediatric anaesthesiology as an alternative device for intubation. They provide sufficient protection for the airway during planned anaesthesia for appropriately selected procedures, and also serve as an intermediate link facilitating intubation in the case of problematic airways. They should not be routinely used when a child is given anaesthesia on a full stomach.

Masks such as i-gel or LMA supreme have an additional channel enabling the insertion of a gastric tube and evacuation of gastric contents.

Tables 8–11 list the types and sizes of airway management devices used in paediatric patients. Table 12 lists the nondepolarizing muscle relaxants used in paediatric anaesthesia.

MAINTENANCE OF GENERAL ANAESTHESIA

During the maintenance phase of anaesthesia, opioids and inhalation anaesthetics in an oxygen-air mixture are most often used. Currently, most anaesthesiologists avoid the use of nitrous oxide due to its penetration into free spaces, which significantly complicates the use of endoscopic surgical techniques – laparoscopy and thoracoscopy, as well as its significantly negative impact on the environment. Global recommendations also indicate avoiding desflurane as a gas that strongly irritates the respiratory tract and significantly contributes to the greenhouse effect – some countries are gradually phasing out the use of desflurane [57].

In justified cases, total intravenous anaesthesia (TIVA) can be performed using propofol (most often), thiopental or ketamine (the latter in haemodynamically unstable children) [58].

During operations requiring muscle relaxation, the administration of muscle relaxants should require monitoring of neuromuscular conduction. The dose of the muscle relaxant to maintain anaesthesia should be selected individually, taking into account the expected duration of the procedure, interactions with drugs administered before and during anaesthesia, and the condition of the child (based on the characteristics of the medicinal product). Inhalation anaesthetics potentiate the effects of muscle relaxants. Available intravenous preparations of nondepolarizing muscle relaxants include rocuronium, vecuronium, atracurium, cisatracurium, and mivacurium. The duration of action and recovery is shorter than in adults.

It is permissible to use low-flow anaesthesia (LFA) techniques, but when using this technique, it is important to maintain the oxygen concentration in the end-tidal mixture above 25% [59].

MONITORING

During anaesthesia, the patient’s vital parameters must be monitored in accordance with the Regulation of the Minister of Health of 16 December 2016 (as amended) on the organizational standard of health care in the field of anaesthesiology and intensive care [28].

OXYGEN THERAPY AND MECHANICAL VENTILATION

PERIOPERATIVE FLUID THERAPY

It should be borne in mind that the youngest patients, especially neonates and infants, due to the immaturity of their kidneys, are less resistant to errors in fluid therapy – both in the case of fluid deficiency and excess. Fluid overload has been shown to be associated with potentially longer mechanical ventilation, heart failure, acute kidney injury, prolonged hospitalization, and increased mortality [67]. In neonates, a positive fluid balance additionally increases the risk of bronchopulmo-nary dysplasia (BPD), intracranial haemorrhage (ICH), necrotizing enterocolitis (NEC), and haemo-dynamically significant patent ductus arteriosus (PDA) [66]. In the youngest patients, the mechanisms regulating normal sodium concentration are also immature, and sodium disturbances may negatively impact the CNS and the child’s further development. Similarly, abnormal glucose levels and hypo-, but also hyperglycaemia are observed more frequently [67]. For the reasons mentioned above, careful fluid therapy is particularly important in this age group.

PREOPERATIVE FLUID THERAPY

Due to the fact that currently the preoperative fast should be very short (1 hour from clear fluids, 3 hours from breast milk, 4 hours from formula), even the youngest children should not have a fluid deficit in the case of anaesthesia for elective surgery [68]. Therefore, even such young patients usually do not require fluid therapy before transfer to the operating room. If the procedure takes significantly longer to begin, the child should be given clear fluid or receive an intravenous infusion (10 mL kg^–1 of isotonic balanced crystalloid).

Fluid depletion may occur during emergency procedures [67]. In such cases, efforts should be made to correct any fluid deficiencies before induction of anaesthesia, as this may reveal previously hidden hypovolemia. If this is not possible, administering a bolus/boluses of 10 mL kg^–1 of isotonic crystalloid, preferably balanced, should be considered before induction.

INTRAOPERATIVE FLUID THERAPY

The goal of intraoperative fluid therapy is to maintain adequate tissue perfusion during the procedure, taking into account baseline requirements, ongoing losses, and any pre-existing deficit. The approximate basic requirements of children are presented in Table 13, and of neonates (babies up to 28 days of age) – in Table 14. Similarly to older children, in the case of infants, it is recommended to use isotonic crystalloid solutions during anaesthesia (these are fluids containing sodium at a concentration of 130–155 mmol L^–1), preferably balanced, without glucose or containing 1% glucose [68, 69]. Balanced crystalloids contain physiological concentrations of chloride and organic anions, for example: acetate, lactate, gluconate, malate, which are a substrate for the systemic production of bicarbonates, thanks to which they have a buffering effect. Large volumes of NaCl-based fluids (e.g., 0.9% NaCl, Ringer’s solution) have the opposite effect and can cause hyperchloremic metabolic acidosis. Even in the youngest patients, as a result of the hormonal response to the stress related to surgery, glucose levels usually increase during anaesthesia, even if glucose-free fluids are used. However, the youngest patients – neonates, especially those born prematurely and/or hypotrophic, full-term babies in the first days of life, as well as infants and children with additional health problems may require intraoperative glucose supply and/or frequent monitoring of its concentration (Table 1). The type of surgery and the anaesthesia are also important; the longer the surgery and the more effective the anaesthesia (e.g. regional anaesthesia effectively eliminating pain impulses), the higher the risk of hypoglycaemia.

In the case of neonates, the most commonly used technique involves two infusions, one of which administers 10% glucose at a rate of approximately 50% of the basal requirement, and the other one administers balanced isotonic crystalloid without glucose, the volume of which depends on the type of surgery and the losses observed. In children under 1 year of age, fluids must be transfused using an infusion pump.

The use of hypotonic solutions (e.g. 5% glucose, mixtures of 5% glucose with 0.9% NaCl: in volume ratios of 4 : 1, 2 : 1, 1 : 1) is strongly contraindicated due to the risk of developing acute hyponatremia and, consequently, cerebral oedema. This risk is due to potentially inappropriate secretion of antidiuretic hormone (ADH), which is a stress hormone. Therefore, the occurrence of acute hyponatremia is possible, although much less likely, even with properly conducted fluid therapy using isotonic crystalloids [68].

POSTOPERATIVE FLUID THERAPY

It is recommended to resume oral fluid (and food) intake as soon as possible. From the anaesthesiologist’s perspective, oral intake can be resumed if the child is awake. In the case of neonates and infants, the child can be breastfed after awakening. If this is impossible due to surgical reasons or the child’s general condition, it is advisable to transfuse isotonic crystalloids, preferably balanced, with 4–5% glucose [67, 68]. Neonates who are unable to take food orally for a prolonged period may require parenteral nutrition, while fluid therapy typically involves 10% glucose with electrolytes – sodium, initially 2 mmol kg day^–1, potassium, initially 2 mmol kg day^–1, and calcium, initially 1 mmol kg day^–1. The composition of the fluid should be modified depending on the monitoring blood gases, electrolytes, glucose, lactic acid, fluid balance, and the child’s body mass. The starting point for calculating the volume of fluids to be transfused should be the basic requirement (Tables 13 and 14). This volume, depending on the circumstances, should be increased if fluid loss progresses, the neonate is kept in an open incubator and/or is undergoing photo-therapy, or more frequently reduced by 30–50%, especially after extensive surgery when an inappropriately high ADH concentration is expected.

EMERGENCE

This is the period of anaesthesia that requires the most attention due to the high risk of complications. It should be emphasized that uncomplicated intubation/LMA insertion does not guarantee equally uneventful removal. Waking up a child from anaesthesia, especially after extubation or removal of the LMA, may be accompanied by adverse events resulting from irritation of the respiratory tract due to the entry of blood, secretions, or tissue fragments into the glottis or bronchial tree (particular attention is required for young ENT patients, often suffering from allergies or early childhood asthma). Coughing, abnormal respiratory movements, laryngospasm, and consequently, desaturation, may be observed. If these occur, a predetermined action plan is necessary, as if left untreated, they can cause hypoxia or even cardiac arrest. Extubation in the lateral position is recommended. Oxygenation for several minutes is also important, as in the induction of anaesthesia. This allows for “buying” time for effective intervention. The younger the child, the less time this will require, due to their greater oxygen requirements. Extubation after the child is fully awake is considered a safer method, but is more likely to be associated with agitation. Extubation during sleep prevents excessive agitation following anaesthesia but should only be performed by experienced anaesthesiologists.

Sometimes respiratory problems after extubation are due to residual neuromuscular blockade, therefore the importance of train-of-four (TOF) monitoring of neuromuscular conduction is emphasized. If a short time has passed since the last administration of a non-depolarizing drug, the patient has a TOF of less than 0.9 or clinical symptoms of residual blockade (jerky movements of skeletal muscles, weak cough reflex), the block should be reversed by administering neostigmine at a dose of 0.05 mg kg^–1 after prior administration of atropine or (ideally) sugammadex; however, it only eliminates steroid preparations from the body.

The condition of a patient in the post-anaesthesia care unit requires assessment and documentation. The Aldrete Scoring System can be used to assess the child’s condition.

POSTOPERATIVE NAUSEA AND VOMITING

It is worth mentioning that children are characterized by a relatively high tendency to nausea and/ or vomiting, also in the perioperative period.

According to the ERAS (enhanced recovery after surgery) protocol, drinking fluids before anaesthesia, especially those containing carbohydrates and electrolytes, is one of the effective non-pharmacological methods for reducing the incidence of postoperative nausea and vomiting (PONV) in children. A similar effect is achieved by drinking fluids as early as possible after surgery, provided there are no surgical contra-indications, even in the post-anaesthesia care unit.

The strategy for preventing PONV begins during the preoperative anaesthetic visit, when the risk factors for PONV should be identified. They can be divided into three groups, depending on the timing and risk of occurrence: preoperatively, intraoperatively, and postoperatively (Table 16). If a child has all four preoperative factors, the risk of PONV is estimated at up to 80%. In these patients, special attention should be paid to observing the fluid withdrawal period before anaesthesia and not extending the fasting period, but rather encouraging the child to take fluids in accordance with the principles described.

Preoperative fluids are also supplemented by sufficient supply during the intraoperative period, and according to a liberal fluid policy, it may be as much as 30 mL kg^–1 in children at medium and high risk of PONV.

In the process of qualifying for anaesthesia and surgery, appropriate procedures should be considered and then implemented. These include:

Prophylactic pharmacological treatment depending on the risk level of PONV is presented in Table 17.

In the treatment of postoperative vomiting and nausea, simultaneous administration of ondansetron with dexamethasone is recommended.

Ondansetron is recommended for both prophylactic and therapeutic use as a single slow intravenous injection (≥ 30 s) at a dose of 0.05–0.1 mg kg^–1 (max. ≤ 4 mg) in patients from 1 month of age, although data for children under 2 years of age are limited. Similarly, dexamethasone may be administered in combination with ondansetron in patients at high risk of PONV at a dose of 0.1–0.15 mL kg^–1 intravenously (max. 5 mg).Other drugs, such as droperidol, tropisetron, dolasetron, granisetron and others, are not covered by the recommendations of the FDA or the European Medicines Agency (EMA) [70, 71].

LARYNGOSPASM

Laryngospasm is caused by reflex contraction of the muscles that close the glottis. It is more common in children, especially the youngest ones [1, 72]. Since improper management of laryngo-spasm may lead to severe hypoxia and even death of the patient, every anaesthesiologist taking care of paediatric patients should know how to prevent, recognize and treat this potentially dangerous complication.

Laryngospasm most often occurs in the youngest patients (under 5 years of age), but can occur in all age groups. It most often appears during the recovery after anaesthesia, then during induction, and least frequently during maintenance [73]. The immediate trigger factor may be irritation of the laryngeal area, for example by blood, secretions or suctioning of the respiratory tract with a catheter, but it may also be a sudden pain stimulus from the operated area when the depth of anaesthesia is insufficient. Table 18 presents the risk factors for laryngospasm [1, 72, 73].

Laryngospasm most often manifests as a sudden inability to ventilate the lungs of a non-intubated patient, retraction of the zygomatic fossa, increased inspiratory effort, and paradoxical movements of the chest and abdomen (the patient attempts to inhale air, but this is impossible or very difficult with a closed glottis), as well as inspiratory stridor during partial spasm. Complete airway obstruction, particularly in a young child with a low oxygen reserve, can quickly lead to desaturation, bradycardia, and even cardiac arrest. The good news is that proper management virtually completely prevents permanent complications of laryngospasm. The key factors are:

The assistance of a second anaesthesiologist should always be sought if the situation requires it, and in the case of inexperienced physicians (even if they are specialists) it should be mandatory [72].

It’s also worth remembering that children who experience laryngospasm may develop pulmonary oedema, a result of the extreme negative pressure in the chest. Therefore, after controlling the critical situation, the child’s chest should be carefully auscultated.

POSTOPERATIVE PAIN MANAGEMENT

The International Association for the Study of Pain (IASP) defines pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Effective pain management, especially in situations of acute pain associated with surgery and painful diagnostic procedures, is not only crucial for improving the quality of life of patients, but it also constitutes the foundation for respecting a fundamental human right – the right to relief from suffering.

Acute pain affects approximately 5% of the population in all age groups. It is estimated that approximately 70% of paediatric patients undergoing surgery experience moderate to severe pain, which demonstrates the importance of effective analgesia in this group of patients.

The main goals of acute pain management in children include:

Effective perioperative pain management requires a carefully developed management plan that addresses the entire medical care process – before, during and after surgery. A key element of this plan is a thorough assessment of the patient’s health status, taking into account both the underlying disease and any comorbidities. Safe and effective perioperative analgesia requires special emphasis on several key activities:

The basic principle of postoperative pain management in children is multimodal analgesia, which combines drugs and techniques targeting different elements of the nociceptive system to improve the effectiveness of therapy, reduce pain intensity, and limit side effects. Severe pain in children should be prevented by implementing preemptive or preventive analgesia. Preemptive analgesia refers to the administration of pain medication before a painful stimulus occurs, such as a surgical incision or other painful procedures. Its goal is to inhibit activation of the nervous system by painful stimuli. In practice, this means administering pain medications before induction of anaesthesia or using analgesia techniques during anaesthesia (e.g., peripheral nerve blocks, local anaesthetic infusion). Preventive analgesia, on the other hand, focuses on preventing persistent pain effects by reducing the activity of the pain system both during and after surgery. The aim of these actions is to block inflammatory and neuropathic processes and increased activity of pain receptors after surgery. All painful procedures, such as insertion of additional intravenous or arterial access or an epidural catheter, should be performed after the child has been induced into anaesthesia. If continuous local analgesia methods (e.g. epidural analgesia) are planned, the first dose of local anaesthetic should be administered before the start of the surgery, which increases the effectiveness of pain control. It is crucial that pain does not wake the child after surgery, which requires proper planning and implementation of effective analgesia methods. Maximum doses of analgesics should not be exceeded during treatment. The most common routes of analgesic administration in children are intravenous and oral. In young children, the rectal route may also be used. When choosing an intravenous route, the following methods can be used: repeated single doses of analgesics at regular intervals, continuous infusions, including a widely used modified patient-controlled analgesia (PCA) option for younger children, known as nurse-controlled analgesia (NCA), which is used in intensive care units. Routes of administration that cause pain, such as intramuscular injections, are unacceptable.

It is important to remember about the possibilities of using non-pharmacological techniques, including: distraction (diverting attention) using elements of play, kangaroo care (skin-to-skin contact with a parent), which reduces the sensation of pain in neonates and infants, relaxation or stimulation techniques, such as acupuncture, acupressure or electrostimulation (TENS – transcutaneous electrical nerve stimulation).

One of the fundamental elements of modern acute pain management in children is regional anaesthesia. Unlike traditional systemic analgesia, regional blocks provide significantly more effective and long-lasting pain control. What is particularly important, this method allows for a significant reduction in the need for opioid analgesics, thus minimizing the risk of undesirable effects associated with their use. Unlike in adults, a regional block in children should be performed under deep sedation or general anaesthesia. This procedure not only increases patient comfort but also improves the precision and safety of the procedure. The role of modern technology in regional anaesthesia deserves special attention. The use of ultrasound imaging and/or a nerve stimulator significantly improves the quality and effectiveness of this type of analgesia. These tools enable precise location of anatomical structures, which results in greater safety and effectiveness of the procedure.

During the initial postoperative period, the child’s condition should be closely monitored, including the level of consciousness and pain intensity. The obtained information allows for the decision to administer another dose of analgesic immediately after the effect of anaesthesia wears off. During this time, it is equally important to verify the extent and quality of regional anaesthesia which may influence the verification of therapeutic assumptions established before the procedure. Further pain management in the subsequent postoperative days is tailored to the patient’s individual needs. This requires constant monitoring of the child’s clinical condition. Properly tailored pain management can ensure greater comfort and a faster recovery. When planning pain treatment for a child, it is important to provide parents or legal guardians and primary care staff with information about the pain management plan, including a gradual, rational reduction of analgesic doses after the patient is discharged from hospital.

Detailed information on the principles of acute pain management in children, pain pharmacotherapy, drug dosing, and pain relief algorithms after surgical procedures is included in the document “Guidelines for the Management of Acute Pain in Children – Position Statement of the Paediatric Section of the Polish Society of Anaesthesiology and Intensive Therapy” [74].

The dosages of the most commonly used anal-gesics in children are given in Tables 19–23.

SUMMARY

Perioperative care of neonates, infants and small children up to 3 years of age is difficult and demanding, which is largely due to the specific nature of this developmental period, different physiology, patho-physiology of diseases, and significant immaturity. All these factors mean that the risk of intra- and postoperative complications in these children is incomparably higher than in the adult population. The homeostatic balance of a child’s body is extremely fragile and only the knowledge and experience of the anaesthesiology team responsible for the child during and after anaesthesia is the basic guarantee of its safety.