Case

Many years ago, a 1 3/12-year-old boy, weighing 7 kg, with a history of preterm birth at 30 weeks of gestation and a birth weight of 600 g, was scheduled for proximal hypospadias repair. After an inhalational induction followed by the administration of 1.5 mg mivacurium he was nasotracheally intubated with a size 4.5 uncuffed tube. Anaesthesia was maintained with desflurane and a continuous infusion of mivacurium. A penile block with two paramedian injections of 0.7 ml bupivacaine 0.75% and a caudal block with 5 ml ropivacaine 0.2% and 2 µg/kg clonidine, preceded by an adrenaline-containing test dose, were performed. A 24G venous cannula was inserted into the left external jugular vein for repeated blood sampling and a BIS monitor was applied.

The anaesthetic course was uneventful over 6 hours with haemodynamic stability and constant respiratory parameters, except for a rise in body temperature which culminated 2 hours after induction at 39 °C. The temperature started to rise when the patient was fully covered by the surgical drapes with only the small surgical field exposed and was still actively warmed by a convective warming system. Because of the stable minute ventilation, malignant hyperthermia was considered to be unlikely. The active warming was stopped and the body temperature gradually came down. In addition, hourly blood gas measurements did not show acidosis or elevated lactate levels. At the end of the case a second caudal was performed, and the child was extubated and transferred to the paediatric intensive care unit (PICU) for further observation.

Just to be on the safe side, creatine kinase (CK) was measured; it was 479 U/l (normal value < 195 U/l) and culminated after 24 hours at 928 U/l. The clinical examination showed a peacefully sleeping child with a normal respiratory rate and a warm periphery. However, the left calf was impressively indurated. Analysis identified continuous pressure applied by the surgical assistant as the most probable causative factor for this localized muscle damage (Fig. 8.1a).

Figure 8.1a Re-staged situation during hypospadias surgery: pressure from the surgical assistant’s forearm caused localized rhabdomyolysis.

Discussion

This case of rhabdomyolysis caused by pressure illustrates the importance of paying meticulous attention to every detail. Staff not regularly involved in the care of small children, in this case a young surgical trainee, often forget that under the drapes lies a small human body and are often unaware how frail a small child can be. Anaesthetists usually immediately ask for a change when surgical colleagues are compressing the thorax and interfering with ventilation. But the anaesthetist should have a synoptic view of the perioperative process, and should give immediate advice if something does not seem to be in the best interest of the patient, even if not directly related to anaesthesia.

Surgery leads to some increase in creatine kinase. In children after minor surgery values of 15–195 U/l have been found, after major surgery 58–770 U/l (Yousef et al. 2006). In adults even higher values, in some case over 1000 U/l, can occur (Laurence 2000). The increase depends on the extent and duration of surgery (Mouzopoulos et al. 2007). CK usually peaks on the first postoperative day. In the reported case the increase in CK was far beyond the expected range caused by penile surgery in a child, where no muscle is cut or squeezed at all. Blood pressure monitoring over a prolonged time can also induce muscle (Srinivasan & Kuppuswamy 2012) or nerve damage (Swei et al. 2009). It is probably unwise to select a very short cycle time over a prolonged period when it is not absolutely needed. In this case the blood pressure cuff was applied on the upper extremity.

The surgical positioning can enhance rhabdomyolysis by a combination of direct pressure on the muscle and a position-dependent low perfusion pressure. This occurs typically with an extreme head-down lithotomy position and has been reported in children too (Bocca et al. 2002). The length of surgery is a relevant factor (Poli et al. 2007). The author remembers a girl who developed severe tenderness of both lower legs followed by muscle weakness, walking difficulties and long-term sequelae after prolonged transanal colorectal surgery in the lithotomy position.

Much more common in daily practice are pressure sores or even localized skin necrosis caused by insufficient padding of a peripheral venous access device (Fig. 8.1b) or a splint for immobilization of the extremity. Because of the high rate of pressure sores in the region of the calcaneus, even when rigorous standards are followed, the author gave up using a splint for the immobilization of a venous access on the foot.

Figure 8.1b Skin necrosis caused by an insufficiently padded peripheral venous access.

Pressure injuries from pulse oximeter sensors that are too tightly attached regularly occur (Ceran et al. 2012), especially when the sensor is secured before induction in an awake struggling child. It is recommended to re-attach the sensor after induction under well-controlled conditions when the child is no longer trying actively to remove it.

Summary and Recommendations

This case reminds us that the anaesthetist should act as advocate for the patient. Not only the anaesthesia but the whole perioperative process should be kept under the anaesthetist’s watchful eye.

Surgery can cause a moderate increase in CK; however, the increase should be minimal after minor surgery in children.

Careful padding of the hub of venous cannulas, as well as ensuring that the attachment of the pulse oximeter sensor is not too tight, can avoid damage.

Case

Decades ago, a 16-year-old girl, weighing 72 kg, was scheduled for Nuss repair of pectus excavatum. After intravenous sedation a thoracic epidural catheter was inserted via an 18G Tuohy needle at the T6/T7 level and loaded with 8 ml bupivacaine 0.25% including 0.5 mg morphine. Anaesthesia was induced with propofol, fentanyl and mivacurium. The airway was secured with a 37F double-lumen tube and the correct position was confirmed by fibreoptic inspection. For maintenance, desflurane and a mivacurium infusion were used.

The patient was positioned with both arms abducted 90°, at the request of the surgeon. It was a re-do procedure, and surgery was demanding. The surgeon claimed that he was constrained by an insufficiently abducted arm, and he moved it more towards the head of the patient, despite the anaesthetist’s comment that this could endanger the brachial plexus.

During the case bupivacaine 0.25% was infused at a rate of 4 ml/h over the epidural catheter; in addition, before extubation, a bolus of 4 ml bupivacaine 0.75% was given. Postoperatively patient-controlled epidural analgesia with bupivacaine 0.125% plus fentanyl 2 µg/ml was used. Therefore, initially weakness of the right arm was attributed to the analgesia technique; however, weakness persisted after reduction and then cessation of the local anaesthetic administration. The diagnosis of brachial plexus palsy was confirmed. There was some improvement over the next few weeks, but even after 3 months the patient was still relevantly impaired during her daily activities.

Discussion

This case of injury to the brachial plexus due to abduction of the arm by over 90° at the shoulder illustrates that positioning can cause nerve damage in children too. They are not resistant to this type of injury. In adults brachial plexus injury is the second most common nerve injury associated with anaesthesia (Cheney et al. 1999). During the Nuss procedure the surgeon needs access to the lateral chest wall, and abduction of the arms is usually requested; however, with abduction of over 90° a 5.1% incidence of transient brachial plexus injury has been reported in this type of surgery (Fox et al. 2005). During cardiac catheterization the arms are often placed hyperextended behind the head, with the risk of overstretching the brachial plexus (Souza Neto et al. 1998). However, such a position is routinely used for diagnostic imaging, e.g. for CT scans, with no negative sequelae; therefore the duration of ischaemia seems to be critical. Rotation of the head towards the abducted arm seems to alleviate the stress on the brachial plexus.

The ulnar nerve can be exposed to direct pressure at the elbow and is the most commonly injured nerve during anaesthesia (Cheney et al. 1999). The elbow should be extended and well padded, with the arm preferably in a supinated position (Prielipp et al. 1999). The author has personally encountered an ulnar nerve injury in a schoolchild whose arm was positioned with the elbow flexed 90° on the operating table (Fig. 8.2).

Figure 8.2 Positioning the arm with the elbow flexed 90° has a high risk for ulnar nerve damage. This undesirable position has to be avoided when children are placed in the lithotomy position.

In the lower extremity, the peroneal nerve is extremely sensitive to pressure, and especially in the lateral position meticulous care is needed to provide sufficient padding of the region around the fibular head. The author once came across a 4-year-old child who had a foot drop for several weeks after renal surgery in the lateral position. Peroneal nerve palsy can also occur after the use of extension devices on a fracture table for femoral fractures in children (Kelly et al. 2017); often the non-operated side, which is less well under control during surgery, is affected. Even in a supine patient, an extreme knee-out position can put the peroneal nerve at risk, especially when the operation takes place in the genital region and the legs are covered by the surgical drapes.

Beside nerve injuries from stretching or direct pressure, pressure sores and skin necrosis can also occur. In very prolonged cases, e.g. over 4 hours, even perfect padding does not exclude every risk, and it is a good practice occasionally to move the patient’s head and if possible the heels just a few millimetres, in order to change the pressure that the tissues are exposed to.

In very delicate patients, normally well-tolerated manoeuvres can lead to fractures. The author remembers more than one femoral fracture caused by positioning and rotations of the leg for heel lancing in preterm babies. And of course the child with osteogenesis imperfecta is a special challenge for the paediatric anaesthetist.

The Nuss procedure is a minimally invasive repair of pectus excavatum which was developed by Nuss in 1987 and has in many places replaced the traditional Ravitch technique. Although the perioperative course is in most cases uneventful, the technique carries several risks which are of concern for the anaesthetist: he or she has to be prepared for dysrhythmias, vascular injury, cardiac perforation, pneumothorax, pleural effusion and haemorrhage. Over almost 20 years the author has personally encountered life-threatening arrhythmias, pneumothorax and pleural effusions, in addition to the brachial plexus palsy of the case described.

Perioperative medicine is a ‘team sport’. High performance by all team members is needed for a good outcome. This is well illustrated by the topic of positioning. The surgeon requires good access to the surgical field, whereas for the anaesthetist minimal interference with ventilation and emergency access to the airway and the intravascular catheters are primary concerns. Both are responsible for ensuring that everything is in the best interest of the patient and that no damage occurs. In some countries the legal aspects of this collaboration are discussed in detail (Auerhammer 2008). In paediatric patients, positioning can interfere extensively with the function of the devices of the anaesthetist as well as with access to the patient, and therefore correct positioning should be among the core competencies of the paediatric anaesthetist.