Support or manipulate pulmonary gas exchange
Normalize alveolar ventilation (PaO2, PaCO2, and pH)
Achieve and maintain PaO2 > 90 mmHg and peripheral Sat O2 > 95 %
Increase lung volume and maintain adequate functional residual capacity (FRC)
Obtain lung expansion and prevent or treat atelectasis
Improve oxygenation and lung compliance
Reduce the work of breathing in the presence of high airway resistance and/or reduced compliance, when spontaneous breathing becomes ineffective
The first measures are constituted by methods of noninvasive ventilatory (NIV) assistance, combining oxygen therapy with the possible application of positive airway pressure and/or of a ventilatory support (high-flow nasal oxygen, NIV equipment), with the use of different interfaces depending on the age of the patient (nasal prong, masks, or helmets) (Figs. 5.1 and 5.2) [4].
Fig. 5.1
Noninvasive ventilatory (NIV) assistance with helmet in neonatal age
Fig. 5.2
Ventilator for noninvasive ventilatory (NIV) assistance
If the newborn and children require intubation, the possibilities of ventilatory assistance can range from techniques of controlled ventilation (mainly controlled pressure) to assisted methods, used in the weaning of patients such as synchronized intermittent mandatory ventilation (SIMV), pressure support (PS), and continuous positive airway pressure (CPAP) [5, 6].
A particular method of ventilation is controlled high-frequency oscillatory ventilation (HFOV) characterized by very small volumes (less than the dead space) and extremely high respiratory rates between 5 and 15 Hz (300 and 900 breaths/min). Oscillatory ventilation produces a series of oscillations (positive and negative) in the airways, with an active expiratory phase, and during the entire respiratory cycle, lung volume is maintained almost constant (Fig. 5.3).
Fig. 5.3
Parameters of respiratory assistance with high-frequency oscillatory ventilation (HFOV)
An interesting ventilatory approach, very useful for the weaning of patients, is the neurally adjusted ventilatory assistance (NAVA) based on neural respiratory control [7, 8]. By NAVA, the electrical activity of the diaphragm (Edi) is captured with an appropriate catheter, equipped with an array of nine miniaturized electrodes, which must interface in the lower esophagus at the level of the diaphragm, in order to obtain the best electrical signal from diaphragmatic fibers. The catheter sends the signals to the ventilator and is used to assist the patient’s breathing [9, 10]. Since the mechanical ventilator and the diaphragm work with the same signal, the mechanical coupling between the diaphragm and the mechanical ventilation is virtually instantaneous (Fig. 5.4).
Fig. 5.4
The electrical discharge of the diaphragm captured through the introduction in the lower esophagus, at the level of the diaphragm, of a NAVA catheter equipped with an array of nine miniaturized electrodes
The ventilation in neonatal and pediatric age during the postoperative course after surgery requires a solid basic understanding of respiratory system mechanics (pressure-volume relationship of the respiratory system and the concept of its time constants) and cardiopulmonary physiology. Furthermore, careful attention has to be paid to avoid damaging the lungs by potentially injurious mechanical ventilation. Optimizing ventilator settings during controlled and assisted ventilation must lead to a progressive and gentle lung recruitment, avoiding the damage caused by strong and repetitive opening/collapse of distal airways and excessive alveolar hyperinflation.
Especially in neonatal age, in the presence of a still immature lung, and in association with problems such as pulmonary infections, sepsis, aspiration of saliva or gastric juice, and severe heart diseases, excessive mechanical ventilation can lead to lung injury, emphasizing phenomena of volutrauma and barotrauma, which can result in a biotrauma, characterized by alveolar damage, with increased microvascular and epithelial permeability, fluid filtration, and pulmonary edema.
This clinical condition can approach an acute respiratory distress syndrome (ARDS), characterized by the absence of secretion or abnormalities in the action of surfactant, resulting in decreased lung compliance and significant hypoxemia. Administration of surfactant, associated with HFOV, may represent an effective method of lung recruitment and alveolar recovery in acute pulmonary injury and in ARDS. Bronchoscopic instillation offers the theoretical advantages that the surfactant may be distributed directly to the desired regions of the lung, with a more economical use of the drug and with the opportunity to lavage leaked serum proteins prior to instillation.
5.4 Cardiocirculatory Treatment
The cardiac output (CO) is the result of the heart rate multiplied by the stroke volume; it undergoes changes according to the variation of the two parameters.
Modifications of the heart rate are able to result in major reductions in cardiac output: bradycardia in children, especially at an early age, causes an important reduction of CO, as the systolic ejection volume does not increase in proportion to the decrease of the heart rate, because of poor ventricular compliance, due to the immaturity of the cardiac muscles.
Tachycardia, up to 200 beats/min, seems better tolerated, as it is accompanied by a proportional increase in CO.
Likewise, limitations in stroke volume also involve a significant lowering of cardiac output. Supporting cardiovascular disease in young patients with digestive surgery must include both principal actions for the overall improvement in stroke volume and specific interventions with antiarrhythmic therapy.
5.4.1 Increase of Stroke Volume
The increase of the CO is achieved, thanks to an increase in the volume of systolic ejection. It depends on and is influenced substantially by three mechanisms:
Increase in the preload
Increase in myocardial contractility
Reduction of the afterload (vascular resistance against which the ventricle pumps the blood volume)
The volume expansion contributes to the increase in preload; it should benefit from the use of crystalloid, colloid, and blood and its derivatives. At first contributions of 10–20 ml/kg isotonic polyelectrolyte solutions are likely to improve the clinical condition with the recovery of peripheral perfusion, decreased heart rate, and the recovery of a viable diuresis. These quantities are usually well tolerated hemodynamically.
Secondly, volume resuscitation of a patient with hypovolemic or septic shock is an essential component of initial patient care. Massive amounts of intravenous fluid are usually administered to replace intravascular volume deficit and to minimize complications attributed to hypovolemia such as tachycardia, hypotension, acute kidney injury, and multiorgan failure. Goal-directed therapies focused on the restoration of normal blood pressure and organ perfusion have been advocated in the management of critically ill patients. Early goal-directed therapy, which is instituted in the initial phase of management of patients with severe sepsis or septic shock, has been shown to improve overall survival [11, 12].
In contrast to the notion of aggressive and liberal volume resuscitation, a growing body of evidence strongly suggests that fluid overload may be detrimental to critically ill patients. Relatively, little attention has been paid to the consequences of fluid overload such as respiratory failure, increased cardiac demand, and peripheral edema. Recent studies on patients with acute lung or kidney injury have reported that fluid overload has been associated with adverse outcomes [13, 14].
The treatment of choice for the optimization of myocardial contractility appears to be the correction of all unfavorable factors (hypoxia, acidosis, hypoglycemia, hypocalcemia, drugs, and toxic substances). Positive inotropic agents, pressor drugs, and vasodilators are indicated as appropriate [15]. Sympathomimetic amines are compounds used in optimizing hemodynamics.
Dopamine is a catecholamine most used in neonatal and pediatric age. Its action takes place on both beta and alpha receptors at a dose of 5–10 mcg/kg/min, respectively. The positive inotropic effect is still mainly due to the release of endogenous norepinephrine. Its positive inotropic effect is modest overall. In patients with renal impairment, it is the drug of choice because at a dose of 3–2 mcg/kg/min, in continuous administration, it ensures a vasodilatation of the splanchnic and renal vascular system. Such action however is discussed for renal and intestinal protection.
Dobutamine increases myocardial contractility, systolic ejection volume, and cardiac output; it decreases the systemic and pulmonary resistance when used in cardiac failure. Even at high doses, it has little effect on heart rate and does not cause an increase in peripheral resistance. It is therefore particularly indicated for patients with severe heart failure. Its action is predominantly beta-adrenergic. This drug is normally used in continuous infusion at a dose of 5–10 mcg/kg/min. It has no specific action on renal and mesenteric circulation and is therefore often used jointly with low-dose dopamine.
Epinephrine is the drug of choice in cardiopulmonary resuscitation (CPR). It possesses potent inotropic and chronotropic effects, associated with action on the alpha and beta receptors of the systemic vascular resistance. In moderate doses it proves to be a real inotropic support in critically ill patients, even when other medicines have not been fruitful; the risk of a response in generalized vasoconstriction is real only at high doses.
In other cases, it is necessary to resort to a reduction in the afterload; the decrease in systemic vascular resistance decreases afterload and increases the volume of systolic ejection, without being accompanied by increased myocardial oxygen demand.
Sodium nitroprusside is a vasodilator with effects on vascular resistance (arteries) and capacitance (veins). Arteriolar dilation produced by this drug reduces the afterload; increased vascular capacitance requires proper support of the preload. It is normally used at a dosage of 0.5–10 mcg/kg/min; its administration requires continuous monitoring of cyanide and thiocyanate metabolites [16].
Nitroglycerin dosage of 1–20 mcg/kg/min has an action prevailing on vascular capacitance with an effective reduction of the preload.
Amrinone is an inhibitor of phosphodiesterase, which has positive inotropic action and is a powerful vasodilator. It is administered slowly in boluses of 0.75–1 mg/kg, followed by continuous infusion of 5–10 mcg/kg/min.
5.4.2 Heart Rate and Rhythm Normalization
Tachyarrhythmias have recently been reported in childhood but can be related to the increased presence of circulating catecholamines, electrolyte abnormalities, metabolic acidosis, hypoxia, and hypercapnia. Pheochromocytoma and hyperthyroidism are the endocrine disorders that most frequently are associated with tachyarrhythmias. Often beta-blocker drugs, especially propranolol at a dose of 0.01–0.1 mg/kg/day, constitute the drugs mainly used, even only to reduce an excessive increase in heart rate.
Supraventricular tachycardia (SVT) is the most common rhythm disturbance in children. Adenosine is considered the drug of choice to correct the SVT. If administered quickly, at a dose of 0.1 mg/kg through a central venous catheter, it causes an immediate reduction in the frequency of the sinoatrial node and the conduction velocity of the atrioventricular node. The doses may be repeated and the dosage increased up to 0.2–0.3 mg/kg, with a maximum total dose of 12 mg.
Ventricular tachycardia, fortunately infrequent in children, requires immediate treatment. In the acute phase lidocaine (1 mg/kg), amiodarone (5 mg/kg) and procainamide (5–15 mg/kg) intravenous are recommended. Electrical cardioversion is indicated when the patient remains unstable despite drug treatment.
5.5 Fluid Management
Fluid management of the pediatric surgical patient represents an important aspect of clinical care, particularly for the initial treatment of the sick child. An understanding of the physiology of fluid requirements is essential for care of these children. Infants and children are sensitive to small degrees of dehydration, and commonly used protocols for pediatric fluid therapy do not consider the rapidly changing perioperative physiology in this patient population. Standard formulas for fluid therapy can be modified to account for these rapid changes in physiology (Table 5.2).
Table 5.2
Postoperative fluid management
Patient weight | Daily fluid intake |
|---|---|
<10 kg | 85–100 ml/kg |
10–20 kg | 1000 ml + 50 ml every kg > 10 kg |
>20 kg | 1500 ml + 20 ml every kg > 20 kg |
Control and distribution of body fluids in neonates, infants, and children are carried out in large part through the kidney and vary according to the different age groups: the total water of a premature infant represents approximately 85 % of body weight, with a redistribution percentage between the extracellular fluid volume (ECV) and intracellular fluid volume (ICV) of 55 % and 30 %, respectively; in term infant the total water constitutes 78 % with an ECV equals to 45% and an ICV to 33 %. Only at 1-year-old (total H2O = 65 %) is the reversal of the percentages of the two compartments witnessed (ICV = 40 % and ECV = 25 %), which is the characteristic of adults (total H2O 60 %, ICV 40 %, and ECV 20 %).
Two aspects are most relevant in designing a fluid therapy in all ages: fluid intake and volume replacement. Intravascular fluid guarantees tissue perfusion; therefore, paying attention to it must have the highest priority. Fluid replacement is necessary to maintain the hydroelectrolytic homeostasis and acid-base balance. Fluid distribution is regulated by osmotic pressure: hypothalamic nucleus is sensitive and responds to very low variations, and this condition causes a hormonal response, involving the secretion of ADH and aldosterone. The dehydrated patient produces more ADH to preserve the H2O. It should be taken into account that during the intraoperative period, ADH secretions may increase due to factors other than the osmotic ones (pain, stress, drugs). For a correct fluid postoperative planning, consideration must be given to the metabolic requirements, intraoperative administration, “third-space” sequestration, blood loss related to surgery, and particular conditions such as the use of radiant lamps for neonates/preterms [17].
Fluid requirements depend on the metabolic expenditure, which is higher in neonatal age. Under normal conditions, 100 ml is required to metabolize 100 Kcal, according to the calculation of Holliday and Segar.
5.6 Analgosedation Management
Effective and adequate therapy to control pain and stress is essential in the management of children in perioperative digestive surgery treatment.
Analgosedation must meet different requirements: adequacy, appropriateness, effectiveness, and safety.
Much evidence confirms that pain and stress must be treated in order to prevent short- and long-term adverse outcomes [18–20].
Not rarely a correct analgosedation management is hard to achieve and overtreatment and undertreatment are both harmful. The complexity and the clinical difficulties due to the age of the patients sometimes induce therapeutic priorities to preserve cardiocirculatory stability or to ensure neurological evaluation, giving up analgesic and sedative drugs and underestimating the consequences of an inadequate pain control and prolonged stress.
Therapeutic necessities of a patient should be set up in advance on dedicated and shared internal protocols, integrated into local context and appropriate to the needs of specific situations, in order to prepare later and progressively an efficient and personalized analgosedation therapeutic plan, according to real needs of the patient.
5.6.1 Pain and Sedation Measurement
Analgesia must be regularly assessed and documented using validated age-related scales.
Self-report scales are preferred instruments for pain assessment in patients with adequate cognitive development. There are several proposals for different ages: the Faces Pain Scale (>3 years), the visual analog scale (VAS), and the numerical rating scale (NRS) (>7 years).
Observational scales must be applied in patients aged less than 3 years or unable to communicate and therefore are the most used in intensive care; some of them, multidimensional, also include the registration of physiological parameters such as heart rate, blood pressure, and SpO2.
Observational scales recommended for neonatal age are the Premature Infant Pain Profile (PIPP) and the Crying, Requires increased oxygen administration, Increased vital signs, Expression, and Sleeplessness (CRIES) scale; for children the Face, Legs, Activity, Cry, and Consolability (FLACC) and the Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) are used.
Pain measurement must be carried out at regular intervals like other vital signs to monitor changes in pain intensity over time and the effectiveness of the treatment. Intervals of 4–6 h may be sufficient if pain control is adequate.
Sedation must be regularly assessed and documented using adequate monitoring scales. The COMFORT scale, validated also for the neonatal age, is the most utilized tool [21].
5.6.2 Drugs for Analgosedation
Measurement of pain and the identification of its underlying causes lead to the choice of analgesic drug, which must be of adequate power and targeted to causal mechanisms.
Acute pain is the form most frequently met in PICU, but complex patients with prolonged stay in intensive care may present with persistent, chronic forms of pain, for which a multimodality approach may be necessary (Table 5.3).
Table 5.3
Postoperative pain management. Multimodality approach
Acetaminophen |
Nonsteroidal anti-inflammatory |
Opioids |
Regional anesthesia |
Local infiltration of the trocar insertion in laparo- and thoracoscopy |
Local wound infiltration |
Nonpharmacological techniques |
Acetaminophen in neonates and acetaminophen and nonsteroidal anti-inflammatory drugs in children above 3 months of age are recommended for treating mild pain (Table 5.4).
Table 5.4
Doses and method of postoperative administration of acetaminophen, main nonsteroidal anti-inflammatory drugs (NSAIDs), and tramadol used in children
Drugs | Administration | Dose (kg/day)
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