|Year : 2017 | Volume
| Issue : 1 | Page : 3-6
Paediatric orthopaedics anaesthesia for surgeons
Serina Ruth Salins
Department of Anaesthesia, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||17-Feb-2017|
Serina Ruth Salins
Assistant Professor, Department of Anaesthesia, Christian Medical College, Vellore - 632 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Paediatric anaesthesia is a well-established subspecialty, which has allowed surgery to be safer, as the science advances in both the specialties. It is imperative for both surgeons and anesthesiologist to be aware of all the implications in children, especially syndromic, coming for surgery. This article gives a comprehensive overview of anaesthesia for orthopaedic surgery.
Keywords: Orthopaedic surgery, paediatric anaesthesia, perioperative
|How to cite this article:|
Salins SR. Paediatric orthopaedics anaesthesia for surgeons. Paediatr Orthop Relat Sci 2017;3:3-6
| Introduction|| |
Physiological differences between a child and an adult necessitate knowledge of basic tenets of paediatric anaesthesia in surgeons treating children to optimize the outcomes. This review describes management of airway, pain, fluid and blood loss, and hypothermia, which are relevant for surgeons.
Preoperative assessment requires a complete history of previous anaesthetics, comorbidities, allergies, and medications. History of reflux, snoring, and upper respiratory infections is elicited, including rare conditions, such as, Malignant Hyperthermia (MH) and prolonged recovery from muscle relaxants, as they may be present in children with muscle disorders.
The general and systemic examination is supplemented with assessment of the airway (mouth opening, neck movements abnormal facies) and surface anatomy for regional anaesthesia. Spinal and rib cage deformities, potential nerve damage or pressure sores because of positioning, and presence of chest infections are assessed. Intravenous access and postoperative pain relief are planned.
Psychological problems may be present in a child who has undergone multiple operations.
Cold is common − children have six to eight upper respiratory tract infections (URTI) per year, but URTIs are associated with an increased incidence of complications under anaesthesia, such as, coughing, breath holding, desaturation, bronchospasm, and laryngospasm. The following approach is suggested for the child with an uncomplicated URTI:
- Urgent surgery – proceed and be ready for complications
- Elective surgery:
- Severe symptoms (“unwell”) – postpone for 4 weeks
- Mild/recent URTI:
- <1 year of age – postpone
- >1 year of age – consider risk–benefit ratio
An incidental heart murmur may also cause concern in a child. This requires further investigations, especially, if the murmur associated with abnormal symptoms or signs, such as failure to thrive, recurrent chest infections, syncope, chest pain, cyanosis, hypertension, palpable heave or thrill, radio-femoral delay, and abnormal electrocardiography (ECG) and chest radiograph.
Fasting is required before any form of anaesthesia for all children. Current guidelines permit solid food up to 6 h, breast milk up to 4 h, and clear glucose containing oral fluids up to 2 h, preoperatively.
Sedative premedication is usually administered in the form of fentanyl lollipop (15–20 micrograms/kg), intranasal midazolam (0.3 and 0.5 mg/kg), or oral trichoryl (75–100 mg/kg), an hour before the planned surgery. This is avoided in those with severe developmental anomalies, obstructive sleep apnoea, airway difficulties, obesity, or infants less than 6 months of age.
Juvenile diabetics on insulin should have their fasting blood sugars checked and morning dose of insulin omitted. Their surgeries should be done earlier on the elective list to avoid prolonged fasting.
Cardiac and asthma medications are usually continued with the exception of digitalis that may be withheld to avoid intraoperative arrhythmias.
Parental consent is obtained for anaesthetic and surgical procedures.
Haemoglobin is routinely checked. Other directed investigations are done when clinically indicated.
Monitoring and emergency equipment
The full range of paediatric anaesthetic equipment, monitoring devices, and disposable items for general and regional anaesthesia is required. The following devices should be available for children of all ages and sizes:
- Airway management equipment − face masks, tracheal tubes, laryngeal masks, oral airways
- Pulse oximetry with paediatric probe
- End-tidal CO2 monitoring
- Paediatric blood pressure cuffs
- Intravenous cannula (24G, 22G, 20G)
- Temperature probe
- Resuscitation drugs and equipment, including a defibrillator
- Anaesthetic machines should include ventilators that permit the use of pressure-controlled ventilation and positive end-expiratory pressure in children of all sizes.
A balanced technique that includes inhalational agents, narcotics, and muscle relaxants with regional anaesthesia is favoured. General anaesthesia is preferred with Sevoflurane for induction and Isoflurane/Desflurane for maintenance. Concomitant regional anaesthesia (central/peripheral neuraxial blocks) help to reduce the need for intraoperative opioids and should be used whenever possible.
For the paediatric orthopaedic surgeon, the understanding of the complexity of anaesthetic problems begins with an understanding of the common multisystemic syndromic associations. The most common factor in these are airway problems because of short neck, relative macroglossia, microdontia, mandibular hypoplasia, atlantoaxial instability, vertebral ligamentous abnormalities, congenital tracheal stenosis, and adenoidal hypertrophy. They cause upper airway obstruction and obstructive sleep apnoea.
| Fluid and Blood Replacement|| |
Intraoperative fluid management aims at normovolemia while avoiding hypervolaemia. Normal saline is commonly used as it is mildly hyperosmolar (308 mOsm) and therefore may minimize tissue edema. However, if given in large volumes (>60 mL/kg), it may lead to hyperchloremic metabolic acidosis. Ringer’s lactate (273 mOsm) and Plasma-Lyte (294 mOsm) are preferred, as they are less likely to cause acidosis.
Resuscitation of a dehydrated or hypovolaemic patient should occur prior to surgery, wherever possible, to ensure an adequate circulation before giving an anaesthetic. To replace a fluid deficit, an isotonic, meaning, solutions which contains the same amount of solute as plasma and hence exerts an equal osmotic force, such as, 0.9% Sodium Chloride or Hartmann’s solution, are commonly used fluids with a bolus of 10–20 mL/kg should be given. Ongoing fluid losses should be calculated and replaced if the loss is greater than 10%, thereby maintaining normovolaemia.
Fluids are administered based on the child’s body weight according to the Holliday and Segar’s inference (4-2-1 formula) that states that the amount of water consumed equates the caloric expenditure depending on the metabolism [Table 1].
|Table 1: Calculation for maintenance fluid requirements for paediatric patients|
Click here to view
Blood glucose should be closely monitored. Hypoglycaemia (serum glucose <30mg/100ml in the first day of life and <45mg/100ml after 24 hours) is common. Glucose can be given as a bolus of 1–2 mL/kg of 10% glucose in addition to maintenance fluid or with the maintenance fluid using a solution containing 10% glucose at 4 mL/kg/h. An alternative method would be to add 25 mL of 50% glucose to 500 mL Hartmann’s solution to create a 2.5% solution. Regular blood sugars should be checked to confirm normoglycemia.,.
| Blood Loss|| |
Paediatric patients when undergoing orthopaedic surgery may potentially have significant blood loss. The goals should be to maintain hemodynaemic stability and oxygen-carrying capacity and prevent and treat hyperfibrinolysis and dilutional coagulopathy.
Perioperative blood loss and its associated progression to hypovolaemia, anaemia, coagulopathy, hypokalaemia, and hypothermia are the most common complications. Hypovolaemia because of blood loss is the most common identifiable cause of anaesthesia-related cardiac arrest in children resulting from underestimation of blood loss in 50% of cases.
High-risk groups for bleeding include those with weight <10 kg, age <18 months, operating time >5 h, and revision surgeries.
Estimated Blood Volume (EBV):
- Premature infants: 90–100 mL/kg
- Term infants: 80–90 mL/kg
- 3 months to <1 year: 75–80 mL/kg
- Older child: 70–75 mL/kg
- Obese child and adult: 60–70 mL/kg
EBV loss of more than 20% is hemodynamically significant loss and >50% is considered as massive loss.
Blood conservation techniques
Some of the strategies in the patient blood management include preoperative tumour vessel or arteriovenous malformation embolization and a restrictive transfusion practice setting a transfusion target of haemoglobin 7 g/dl instead of 9 g/dl.
Intraoperative blood/cell salvage is another option that involves collecting autologous blood from the surgical site to be processed and given back to the patient during the surgery. Acute normovolaemic haemodilution and hypervolaemic haemodilution are additional strategies.
The most common class of drugs to improve haemostasis during major surgery include the lysine analogues that competitively inhibit the activation of plasminogen to plasmin, tranexamic acid (TXA) and epsilon aminocaproic acid (EACA), and the serine protease inhibitor, aprotinin. TXA is the most common antifibrinolytic used worldwide.
TXA dose of 10 mg/kg bolus and infusion of 5 mg/kg/h has been recommended using pharmacokinetic modelling. TXA and EACA have side effects, similar to thromboembolic and seizures phenomenon.
| Pain|| |
Inadequately treated pain may have long-term negative effects on pain sensitivity, immune functioning, neurophysiology, attitudes, and healthcare behaviour. It is therefore essential that healthcare professionals looking after children of all ages are trained to recognize and treat pain whether it be acute or chronic.
The main causes of acute pain in children are from procedures, surgery, trauma, and acute medical illness. Factors, such as education of staff involved in caring for the patient, pain assessment, anticipation of pain, provision of a calm environment and the inclusion of parents, aide successful pain management.
The aim of pain management in this setting is to control pain as early as possible and therefore the initial choice of drug and dose should be appropriate and titrated to response.
Paediatric pain management includes the principles of multimodal analgesia whereby different classes of drug are utilized to gain maximum effect.
| Pharmacological Therapies|| |
Nonsteroidal anti-inflammatory drugs and paracetamol
This forms the mainstay of postoperative pain relief. Use of nonsteroidal anti-inflammatory drugs is not recommended below 6 months of age because of the possibility of immature renal function and hepatic metabolism. Most commonly used agents are:
- Diclofenac (1 mg/kg, PO/PR 8 hourly prn)
- Ibuprofen (5–10 mg/kg PO 6–8 hourly)
- Paracetamol (10–15 mg/kg PO/PR/IV, max. of 60 mg/kg/day for <3 months, 90 mg/kg/day in older children
Short-acting opioids are ideal (fentanyl; 1–2 mcg/kg) and long-acting opioids (morphine; 0.05–0.1 mg/kg) are commonly used. Side effects of opioids, such as respiratory depression, pruritis, sedation, nausea and vomiting, and bladder retention, should be carefully monitored.
Central and peripheral nerve block anaesthesia is considered to be safe and effective in paediatric patients in both emergency and elective surgical procedures of the extremities, especially, with the advent and use of ultrasound guidance, which enables visibility of structures, hastens the onset, improves intra and early postoperative analgesia, and lowers anaesthetic requirements. Regional anaesthesia may aid tissue perfusion by its vasodilatory action and many hazards associated with general anaesthesia are avoided. The hazards are same as that of in adults. Therefore, the same precautions should be taken, in terms of technique and dosage of drug.
- Central neuraxial blocks: spinal, epidural, caudal
- Peripheral blocks: head and neck, upper and lower extremities, thorax and abdomen
- Lignocaine (2% – 7 mg/kg with adrenalin, 5 mg/kg without adrenalin)
- Bupivacaine (0.5% – maximum, 2 mg/kg)
- Ropivacaine (0.75% – maximum, 3 mg/kg)
The above-mentioned agents can be used for surgical anaesthesia with lower doses of the same used for analgesia.
| Temperature|| |
Hypothermia during surgery in children leads to increased surgical-site infection, adverse cardiac events, coagulopathy, increased transfusion requirements, and prolonged intensive care and hospital stay. Children are more prone to hypothermia because of higher conduction and radiation heat loss and less subcutaneous fat. They also have a higher surface area. Intraoperative warming methods, such as fluid warming devices, fluid warmer, and warming blankets, need to be employed. In addition, simple measures such as sheets and hats prevent conduction and convection heat loss. Ambient theatre temperature can be maintained at 20–23°C. Attempts should be made to limit exposure of large areas of skin surface, particularly wet skin, while waiting for surgery to start, and gases used to ventilate may be humidified by a heat and moisture exchanger.
Core temperature can be monitored at several sites including the rectum, nasopharynx, esophagus, temporal artery, bladder, tympanic membrane, and blood measurement. Noncore temperature measurement can be obtained using axillary thermometry or skin probes [Table 2].
Children receiving active warming intraoperatively are at risk of overheating and burns from nonuniform warming devices. The effects of hyperthermia include localized, increased skin and muscle blood flow, increased vascular permeability and edema, and ultimately cell death and organ failure. As such, vigilance must be exercised throughout the perioperative course for hyperthermia, and all children receiving active warming must have continuous temperature monitoring.
MH may be strongly considered as part of the differential diagnosis despite weak evidence to support the diagnosis of MH. Fortunately, most syndromes are rarely associated with MH or MH-type reactions. Other possible causes of elevated temperature include metabolic syndromes, sepsis, adverse drug reactions, central nervous system disturbances, transfusion-related issues, or heat stroke. A number of retrospective studies have recently become available that refute the association between MH and certain congenital conditions such as osteogenesis imperfecta.Dantrolene is the drug of choice for MH. Dantrolene is a skeletal muscle relaxant that directly blocks intracellular calcium from being released in the sarcoplasmic reticulum.
However, its exact mode of action and molecular mechanisms are still not completely known. The dose is: bolus – 2.5–4.0 mg/kg, followed by 1 mg/kg every 4 h for 48 h.
| Postoperative Nausea and Vomiting|| |
This may cause discomfort and distress, delay recovery, and prolong hospitalization. A multimodal management approach includes:
- Reduce the use of emetogenic drugs such as opioids
- Perioperative intravenous hydration
- Adequate pain control with increased use of regional anaesthesia
- Multiple different antiemetic medications as a combination antiemetic therapy acting at different neuroreceptor sites. The common drugs include:
- Ondansetron (0.05-0.1 mg/kg IV)
- Dexamethasone (0.15 mg/kg IV)
- Metoclopramide (0.1 mg/kg IV)
| Conclusion|| |
It is the professional responsibility of the paediatric anaesthesiologist to deliver care to the best of their ability in the operating room. The complex interactions of coordination of care, organizational culture, communication between nursing and surgical teams, and practice guidelines affect performance of safe and scientific anaesthetic provision.
A culture of safety is one that encourages open discussion of mistakes, transparency, and system-based thinking as opposed to blaming individuals. Therefore, the basic factors, as discussed in this article, are more than sufficient to facilitate the same.
The author would like to thank Dr. Indrani Sen.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]