Introduction
Problems will vary from the orthognathic to those of a more general nature, which can be life threatening. Although orthognathic surgery is usually carried out on young fit adults, life-threatening complications may arise. Careful technique, and expertise in the management of serious emergencies are essential. This includes the understanding the mysteries of medical monitoring.
Medical Monitoring (Figure 14.1)
ECG: a basic knowledge of abnormal PQRST complexes and arrhythmias is essential for interpreting the ECG. “Three-lead” monitoring gives an interpretable rhythm-strip but is no replacement for a full “12- lead” ECG assessment when acute cardiac problems are suspected.
Heart rate (HR): derived from the ECG and the monitor can be set to detect bradycardia and tachycardia.
Arterial blood pressure (ABP): is measured by direct cannulation of the radial, brachial, dorsalis pedis or femoral arteries. The mean arterial pressure (MAP) is denoted in brackets. Non-invasive monitoring (NBP) is done with an appropriately-sized pneumatic cuff placed either around the upper arm or lower leg.
Central venous pressure (CVP): is useful as an indication of right ventricular preload. Serial readings (i.e. the trend of CVP measurements) are far more useful than single readings. The normal value is 2-6 mmHg. Respiration (RESP): is normally 14-20 a minute.
Figure 14.1 Intensive Care Monitor (by courtesy of Panasonic). (a) Heart rate. (b) Continuous invasive blood pressure (BP). (c) Current mean arterial pressure. (d) Oxygen saturation. (e) Central venous pressure. (f)Temperature. (g) Respiratory rate. (h) End tidal CO2. (i) Non-invasive cuff BP.
Oxygen saturation of arterial blood (SpO2): is usually measured by a digital pulse oximeter based on the light absorptive properties of oxygenated and deoxygenated Hb. Oxygen saturation monitoring, which assesses oxygenation, not ventilation, is no substitute for arterial blood gas assessment as there are both extrinsic and intrinsic reasons why the reading may be inaccurate.
Carbon dioxide: is expressed in a graphic form by the capnograph. Capnography is an indirect monitor that not only helps in the differential diagnosis of hypoxia, but also provides information about CO2production, alveolar ventilation and respiratory patterns.
Temperature: can be monitored by mouth, axilla, tympanic membrane, oesophagus and rectum. Rectal and oesophageal measures are the most accurate.
Complications
1. Oedema and Infection
Oedema is reducible with pre-and postoperative dexamethasone and antibiotic cover as described earlier. Contrary to some popular practice vacuum drains can dramatically reduce the swelling arising from mandibular osteotomies, and the minivacuum drain is equally valuable for infraorbital haematomas following dissection through a subciliary incision. The same applies to the iliac crest donor site. Where possible leave drains for at least 24 hours after they cease to function.
Where there is gross postoperative swelling and pain, the presence of a haematoma is more likely than oedema alone. Treatment should be the release of the haematoma, especially if expanding, as it may be the presenting feature of a persistent arterial bleed, which needs to be identified and arrested.
There is some dispute as to whether clean operations require more than one pre-and postoperative antibiotic bolus. However prospective trials have shown that a five-day course produces less postoperative infection at the sagittal split site.
2. Bleeding Problems
a) Minor Haemorrhage
Even with previously healthy patients not receiving any medication which would predispose to excess bleeding, intraoperative blood loss is significantly reduced by the administration of an antifibrinolytic agent such as tranexamic acid 25 mg/kg orally or 0.5-1 g by slow intravenous injection pre-and postoperatively.
Tearing the periosteum on the medial aspect of the ascending ramus whilst exposing it for a sagittal split may produce a troublesome bleed, which can be controlled with a hot wet tonsil swab and pressure for 3 minutes. Damage to the facial vessels through the base of the subperiosteal pouch prepared for the mandibular buccal cortex cut responds to the same pressure and patience. Rarely the maxillary, tonsillar or lingual arteries may be damaged, giving rise to prolonged serous haemorrhage. Again, packing firstly with a swab, and secondly with a large piece of oxidised cellulose (Surgicel) should be sufficient, assisted by 0.5-1 g t.d.s. tranexamic acid (Cyclokapron, Kabi) given intravenously. If vigorous bleeding persists the external carotid may need to be tied off, as described below.
b) Persistent Haemorrhage
Failure to control bleeding despite efficient conservative measures may be due to the following.
i) A patent damaged artery, either the maxillary or tonsillar that require identification and ligation. Do not delay ligation of the external carotid if significant bleeding persists despite local ligation, packing and antifibrinolytic therapy for more than 30 minutes. This should allow time for investigation.
ii) A rare manifestation of a latent coagulation defect or defibrination. In both cases there is an evident lack of clot formation on the drapes and the wound oozes “watery blood”.
c) Management — General
Ensure early that adequate blood is available for replacement; if not, send venous samples for full blood count, cross-matching and a clotting screen which must include the thrombin time, prothrombin time (PT or INR), thromboplastin generation test, fibrin degradation products and a platelet count. In rare cases of acute defibrination there are prolonged prothrombin time (PT), activated partial thromboplastin time (APPT) and thrombin time (TT), increased fibrin degradation products and reduced platelets. The increased fibrin degradation products tend to have an anticoagulant effect.
Maintain the circulation with crystalloid solution until type specific or fully cross-matched blood is available. Remember the circulating blood volume in an average adult is around 5000 ml (75 ml/kg), and transfusion is required after a 20%-30% loss. In a child the circulating blood volume is equal to the weight in kilogrammes × 80 ml, and therefore a relatively small absolute volume will give a 20% loss.
d) Ligation of the External Carotid Artery
Clean the neck with detergent and iodine. Resist the temptation to use an aesthetic skin crease incision, as this will limit access if the neck is distended with blood. Always incise obliquely along the anterior border of the sternomastoid muscle (Figure 14.2a). Remember the carotid bifurcation is just below the level of the hyoid bone. Therefore incise obliquely downwards from two fingers' breadth below the angle of the mandible to the level of the prominence of the thyroid cartilage along a line drawn from the mastoid process to the sternal notch. Deepen the wound through fat, platysma and fascia using a No. 10 or 20 blade until the anterior border of sternomastoid muscle can be felt and seen.
The sternomastoid must be retracted firmly with a broad Langenbeck. The carotid triangle contains fine filamentous fascia, unless it has become infiltrated with oedema due to prolonged bleeding into the neck.
The carotid sheath fascia overlying the internal jugular vein is picked up with toothed forceps and incised along the vessel with McIndoe scissors. Anylon tape is passed around the internal jugular, once revealed, and attached to artery forceps; the vein is retracted distally with the sternomastoid muscle (Figure 14.2b).
Figure 14.2(a) Skin incision at upper anterior border of sternomastoid. (b) Opening of carotid sheath with retraction of internal jugular vein to reveal the carotid artery. (c) Ligation of external carotid artery.
The carotid will now be palpable and partially visible; again, fascia will need to be divided to expose the bifurcation. This may be obscured by one or more small veins, which must be tied with 3/0 polyglycollate or linen and divided. The external carotid is anteromedial to the internal carotid and can be identified by its branches. The superior thyroid artery often arises at the bifurcation and has to be ligated with a black silk or linen and divided to gain access to the main trunk. Ligatures are more easily passed around the vessel with small Adson's artery forceps as they have a more pronounced right angle curve. Rather than search for a specific vessel it is better to tie the external carotid at its base. There is no need to divide it (Figure 14.2c).
A vacuum drain is inserted and sutured to the skin with 3/0 black silk and the wound closed in three layers using 3.0 polyglycollate for the platysma and subcutaneous layers and 5/0 interrupted Prolene sutures for the skin.
An absorbent non-adhesive dressing is then secured with adhesive tape.
e) Coagulation Defects
Persistent bleeding despite local and carotid ligation indicates either a factor deficiency (the most common unsuspected defect being von Willebrand's disease) or disseminated intravascular coagulation (DIC). By now the laboratory results should be available. A prolonged thromboplastin generation test suggests a missing clotting factor. The prothrombin time (INR) will not be of value unless this is an anticoagulant or advanced liver disease problem, which is unlikely in an osteotomy patient. If however, there are also raised fibrin degradation products and deficient platelets, DIC should be assumed to be the problem. Management should be as follows.
i) Maintain tissue perfusion and oxygenation with intravenous fluid support and supplemental oxygen.
ii) Fresh frozen plasma (FFP), which contains clotting factors as well as the natural anticoagulants antithrombin III and protein C, is given in doses of 15 ml/kg. Cryoprecipitate is given along with FFP to replace fibrinogen if levels are less than 80 mg/dl.
iii) Platelet transfusion, 1 unit/10 kg body weight, should be considered once platelet counts drops below 50,000/cu mm and also packed cells to replace erythrocytes.
iv) Antifibrinolytic agent (tranexamic acid 0.5-1 g IV) must be used to arrest the fibrinolytic process and conserve the clotting factors. However once this process has been recognised it is essential to consult a clinical haematologist for advice.
v) Any patient receiving a large volume of blood replacement (1-1.5 of the circulating volume within 24 hours) will require FFP, cryoprecipitate and platelets. At this stage a clinical haematologist should guide all blood product prescribing. Recombinant activated Factor VII is being increasingly trialled as a treatment for persistent bleeding but its use is currently restricted by the small evidence base and the high costs (£5000 for a single 4.5 mg vial).
vi) The patient has by now been infused with 5-10 litres of fluid, much of which will be distending the bladder. This will require an indwelling catheter (see below), not only to decompress the bladder but also to help calculate the state of fluid balance and renal perfusion.
vii) Continued bleeding into the tissues may fill the soft palate, the lateral wall of the pharynx and the neck, constituting a serious threat to the airway postoperatively. Blood will also have passed the throat pack into the larynx and almost certainly into the stomach. The airway can be managed by prolonged endotracheal intubation but this will be dependent on skilled postoperative intensive care. If support is not available, an early decision should be made to carry out a tracheostomy, which not only guarantees the airway but also prevents aspiration into the lungs of blood or gastric contents and allows aspiration of accumulated secretions from the bronchi.
viii) Remember to administer metoclopromide 10 mg and erythromycin 250 mg intravenously to promote gastric emptying of swallowed blood. Metoclopromide is a dopamine antagonist, which stimulates gastric emptying, and small intestinal transit whilst also enhancing the strength of oesophageal sphincter contraction. Erythromycin and related 14-member macrolide compounds act directly upon motilin receptors in gastrointestinal smooth muscle and, therefore acting as motilin receptor agonists, and also accelerate gastric emptying, increase the frequency of smooth muscle contractions, and shorten orocaecal transit time.
ix) Before the patient leaves the theatre a Ryles nasogastric tube should be passed to aspirate the blood and bile reflux from the stomach. Gastric acid reduction as a prophylaxis against aspiration may also be achieved by giving a proton pump inhibitor such as omeprazole 40 mg by slow intravenous injection. Under normal conditions the effects of proton pump inhibitors are enhanced if the drug is given the evening before surgery and again 2 hours prior to surgery commencing. However this is not possible in cases of surgical emergency.
f) Secondary Haemorrhage
The patient may suddenly bleed profusely postoperatively in the ward, or even at home. The common causes are a partially divided large vein or untied artery in the depths of a mandibular osteotomy wound. Occasionally an undetected coagulopathy such as von Willebrand's is the underlying problem, especially when the bleeding is repeated.
The management must commence with pressure applied to the bleeding site with swabs, and rapid transfer to theatre for exploration and haemostasis, as described.
As with all severe haemorrhage up to 10 mg intravenous morphine should be given immediately by slow intravenous injection as a sedative analgesic, together with tranexamic acid 0.5-1 g intravenously to help conserve clotting factors and clot in favour of haemostasis.
g) Gastric Haemorrhage
The chance of stress-induced gastric erosion is small, even after prolonged orthognathic surgery. However, the combination of a patient with a history of peptic ulceration, a stressful surgical procedure, anti-inflammatory steroids and analgesics can produce a gastric bleed. Abdominal discomfort, tachycardia, true melaena and/or haematemesis and a fall in haemoglobin (a late sign) should alert one to this possibility. Initial treatment should include intravenous fluid support and administration of a proton-pump inhibitor (omeprazole), first as an intravenous bolus dose (40 mg), then as an intravenous infusion for 72 hours. Early endoscopy should be considered after consultation with a gastroenterologist so that the bleeding point can be injected or banded.
The aim of drug treatment is to raise gastric pH to above 4, thereby stabilising any clots that may have formed at the bleeding site. This is the reasoning behind the use of proton pump inhibitors over H2 receptor blockers such as ranitidine, which have a lesser effect on pH.
With vulnerable patients a regular prophylactic proton pump inhibitor, such as omeprazole or lansoprazole, should be administered as well as eliminating both steroids and non-steroidal antiinflammatory analgesic drugs from the intraoperative and postoperative regimen.
3) The Airway
After an uneventful operation, the airway should be maintained with a nasopharyngeal tube, which is sucked out throughout the postoperative 12-18 hours at 30-minute intervals. Unless the nurse ensures that the fine suction catheter passes beyond the end of the nasopharyngeal airway tube, the end will gradually become blocked with blood clot and will become an efficient airway obstruction (Figure 14.3a) the same can occur with a tracheostomy tube (Figure 14.3b). Some anaesthetists leave an endotracheal tube in situ which with modern closed suction units can be kept unobstructed with minimum effort and nursing intervention.
A facemask with 40% oxygen at a flow rate of approximately 5 litres/min ensures adequate tissue perfusion. In intensive care or high dependency units an intra-arterial line may have been inserted to monitor blood gases and invasive blood pressure is displayed on the cardiac monitor as a continuous arterial pressure trace. But this is not an alternative to the provision of a good airway by careful suction and good nursing. Continuous monitoring via a peripheral oxygen saturation probe will give early warnings of evolving airway obstruction and hypoxia.
Figure 14.3 Clot obstructing (a) endotracheal tube and (b) tracheostomy tube.
Nasal obstruction with blood clot and mucous crusting can be prevented by steam inhalations containing Friar's Balsam or some similar aromatic vapour.
Occasionally an asthmatic patient develops acute bronchospasm and airway obstruction despite the dexamethasone cover. This may be resolved by a salbutamol nebuliser; 2.5-5 mg of salbutamol in a pre-prepared solution via a nebuliser mask on 8 litres oxygen per minute repeated as required, with 500 mcg of ipratropium bromide (an antimuscarinic bronchodilator) added 6-hourly. In addition intravenous magnesium (2 g in 100 ml normal saline) over 30 minutes is now an accepted part of The British Thoracic Society Guideline for severe acute asthma management. Magnesium induces relaxation of bronchial smooth muscle in acute asthma by interfering with calcium transport mechanisms and intracellular phosphorylation.
With these basic conservative measures, emergency tracheostomies are rarely needed.
h) Emergency Airway Procedures
Acute upper airway obstruction is more likely to follow trauma then operative procedures. In the non-intubated patient, obstruction secondary to haemorrhage into the neck tissues may prevent the clinician from inserting an endotracheal tube through the cords to establish airway patency. In such cases needle cricothryroidotomy and surgical cricothyroidotomy may be used to maintain ventilation and oxygenation whilst formal endotracheal intubation is attempted.
i) Needle cricothyroidotomy and jet insufflation can provide supplemental oxygenation for around 20-30 minutes, the time constraint being carbon dioxide retention, as only minimal expiration is possible through the obstructed airway via this method. This relatively simple technique buys time to perform more definitive airway procedures by a clinician skilled in difficult and emergency situations.
Technique
Attach a 12-14 gauge cannula to a 10 ml syringe.
With the patient in a supine position extend (neutral in acute trauma) the patient's neck whilst controlling the head.
Palpate the cricothyroid membrane and then stabilise the trachea between thumb and forefinger of the nondominant hand to prevent lateral movement.
Puncture the skin in the midline with the cannula needle directly over the membrane, directing the needle at a 45° angle caudally.
Insert the needle through the lower half of the membrane, aspirating as the needle is inserted.
Aspiration of air indicates entry into the tracheal lumen, at which point the catheter can be carefully advanced into the lumen whilst withdrawing the needle.
Oxygen tubing attached to a Y-connector or with a hole cut into the side is attached to the hub of the catheter.
Intermittent insufflation can be achieved by occluding the open limb of the Y-connector or the hole in the tubing with a finger for 1 second and releasing for 4 seconds, during which oxygenation and then some passive expiration can occur. Expiration is limited as it occurs through the partially obstructed airway and not through the lumen of the inserted catheter.
Oxygen flow is commenced at 10 litres per minute and increased in increments of 1 litre until chest wall movement is observed during the period of hole occlusion.
As well as allowing oxygenation via jet insufflation, needle cricothyroidotomy can be used to carry out a retrograde intubation. After initial insertion of the needle through the membrane has been confirmed by aspiration of air, a guide wire is passed through the needle cephalad. This wire should pass upwards into the pharynx and then grasped with forcepts to be brought out through the mouth. An endotracheal tube can then be passed over the wire into the larynx. The wire is removed once the tube reaches the level of the membrane and the tube is then passed further into the trachea.
ii) Surgical cricothyroidotomy involves the insertion of a small endotracheal tube or tracheostomy tube through the cricothyroid membrane. Using this method the patient can be successfully oxygenated and ventilated with a bag valve system with supplemental oxygen until intubation or retrograde intubation is achieved. This technique is not recommended for children under 12 years of age in whom damage to the cricoid ring is likely.
Technique
Place the patient in the supine position with the neck in a neutral position.
Prepare the skin and anaesthetise the area if the patient is conscious.
Identify the cricothyroid membrane between the thyroid and cricoid cartilages.
Stabilise the thyroid cartilage with the non-dominant hand to prevent lateral movement.
Carefully make a transverse skin incision over the membrane and then incise through the lower half of the membrane.
Open the airway by using either a haemostat, a tracheal spreader, or by inserting the scalpel handle through the incised membrane and rotating it through 90°.
Insert the endotracheal or tracheostomy tube through the incised and opened membrane, directing it distally into the trachea.
Inflate the cuff and secure the airway using either sutures or ribbon ties.
Attach a bag valve system that is connected to a high flow oxygen source to the tube and ventilate the patient, observing for chest wall movement to indicate lung inflation.
iii) Tracheostomy: The need for elective tracheostomy has diminished with improved anaesthetic techniques and emergency care. However, the emergency tracheostomy, especially where there has been marked uncontrolled blood loss into the tissues, is still essential for untroubled postoperative care if prolonged endotracheal intubation cannot be adequately supervised. It provides an assured airway with reduced dead space, easy access for the aspiration of secretions from the bronchi below and prevents aspiration into the bronchi from above.
Technique
Place a sandbag between the shoulders and maximally extend the head on the neck to elevate the trachea (Figure 14.4a).
Figure 14.4 Tracheostomy technique, details on pages 457, 459 and 460.
Prepare the skin from the lower border of the mandible to below the clavicles with povidone-iodine. If there is no hurry, mark the incision and infiltrate it with a vasoconstrictor solution.
A horizontal 5 cm incision is made halfway between the prominence of the thyroid cartilage and the sternal notch with a No. 10 blade. Incise through the fatty superficial fascia and platysma down to the muscle layer, revealing the anterior jugular veins on both sides. These may be divided and tied, or undisturbed and ignored if there is any urgency. Retract the flaps with cat's paws or a selfretaining retractor (Figure 14.4b).
Incise vertically in the midline with a knife or scissors, separating the intramuscular fascia and revealing the pretracheal fascia.
Retract the strap muscles laterally.
Lift up the pretracheal fascia with toothed forceps and incise upwards with scissors to reveal the isthmus of the thyroid, and then downward, avoiding if possible the centrally placed inferior thyroid vein (Figure 14.4c). If the thyroid isthmus is large it may be retracted upwards with a broad Langenbeck. Occasionally it may be necessary to clamp the isthmus with long curved haemostats and divide it. To prevent bleeding, the margins should be carefully tied with 2/0 polyglycollate before releasing the clamps.
Re-position the retractors inside the pretracheal fascia on either side of the trachea. If time allows, or if using local analgesia, infiltrate between the second and third tracheal ring with 1 ml 2% lignocaine containing 1:80,000 adrenaline for haemostasis, then inject another 1-2 ml into the lumen. This anaesthetises the mucous membrane and helps to suppress the violent cough reflex when inserting the tube.
Make a horizontal slit between the second and third tracheal ring with a No.15 blade and extend it downwards bilaterally. The trachea may be steadied by passing a tracheal or skin hook beneath the upper ring and gently elevating. The simplest technique is now to remove a circular disc of trachea and then pass a 1/0 black silk stay suture around the lower ring and clip it outside the lower wound margin (Figure 14.4d).
Some surgeons prefer a Bjork flap, which is an inverted U hinged inferiorly (Figure 14.4e). The upper margin of the flap is sutured to the skin surface. This enables re-intubation if the tracheostomy tube is displaced or removed. However, the tracheal defect tends to be larger and there may be a greater incidence of post-tracheostomy stenosis.
Choose a suitable size of tracheostomy tube, 33 to 39 for small to large individuals, and test the cuff by inflating with air.
Insert the tracheostomy tube gently as the anaesthetist withdraws the endotracheal tube, carefully sucking all blood from the area. Inflate the cuff with a 20 ml syringe, noting whether it is self-sealing or requires clamping and sealing with its own spigot (Figure 14.4e).
The endotracheal tube is now completely removed and the anaesthetic hose connected to the tracheostomy tube
Suture the skin margins beneath retaining flanges with interrupted 3/0 Prolene or silk as far medially as possible. Cover the wound margins with an acriflavine-impregnated gauze swab or Telfa pad which has been prepared with a T-shaped cut to fit around the tube.
Tie the tube flanges behind the neck with tapes to prevent displacement.
Postoperative Care
Secretions must be sucked out regularly every half hour, and more frequently if necessary, with a fine catheter and using an aseptic technique
The tracheostomy oxygen must be warmed and humidified.
High volume, low-pressure cuffs no longer need to be released at intervals to prevent ischaemia of the tracheal mucosa but the cuff pressure should be checked.
A chest radiograph must be taken postoperatively to exclude pleural damage and pneumothorax. Note: surgical emphysema of the neck may be dramatic but is of no consequence.
Daily physiotherapy is essential, with gently catheter suction and warm saline to loosen the secretions.
Once the oral and cervical swelling has receded and the chest radiograph is clear, the tracheostomy should be removed. The skin is cleaned with detergent (Savlon) and the tube is sucked out with the patient upright and is then withdrawn. Steri-strips may be used to close the margins of the wound, which is then covered with a dry gauze adhesive dressing and is left unchanged, and sealed for 10 days. Complete spontaneous closure usually takes place in a week. If there is any delay, swabs taken from the wound will show gross antibiotic resistant contaminants. Avoid the temptation to use exotic antibiotics when local cleansing with 0.05% hibitane or povidoneiodine dressings is all that is required.
As osteotomy cases do not require a prolonged tracheostomy, replacement of the tube does not arise.
4. Drainage of a Pneumothorax
Occasionally, despite every care on removing a rib graft, there is a breach in the pleura and the patient develops a pneumothorax. The presenting signs are breathlessness and tachypnoea with absent breath-sounds over the area. The typical radiographic appearance where the visceral pleura is breached is a demarcated peripheral area devoid of lung markings — here seen on the left side (Figure 14.5a). However Figure 14.5b shows a mottled oval opacity of surgical emphysema in the right lung field overlying a pneumothorax where both visceral and parietal pleura have been breached following costochondral graft removal.
The most convenient, comfortable and cosmetically pleasing site for drainage is in the fourth or fifth intercostal space in the mid-axillary line. To achieve this, the patient must be comfortably positioned, either reclining on the bed with the ipsilateral arm behind the head to expose the axilla, or leaning forward, with folded arms resting on a pillow on the bed-table. The surgeon should scrub, gown and put on gloves. The skin is prepared with povidone-iodine and, with sterile towels to isolate the area, is infiltrated with 1% or 2% lignocaine. Then with a 21-gauge needle (green hub) the chest wall is infiltrated to the pleura (up to 3 mg/kg), at which level air can be aspirated. Always keep to the upper rib border to avoid the intercostal neurovascular bundle that runs along the inferior border of the rib. Asmall skin incision is made and then blunt dissection used through the superficial fascia and intercostal muscles to the pleural space.
Figure 14.5 (a) Left pneumothorax due to breach of visceral pleura producing a demarcated peripheral area devoid of lung markings. (b) Oval mottled opacity of surgical emphysema overlying right pneumothorax due to breach in parietal and visceral pleura.
Small calibre chest drain sets (8-14 F) come with a Seldinger technique insertion kit. The method involves passing dilators of increasing size into the pleural space over a guide wire that has initially been introduced through a hollow needle. This creates an almost bloodless and atraumatic tract into the space required, through which the chest drain can be passed prior to connecting it up to an underwater drainage system. The use of the rigid trochar is contraindicated for all sizes of drain due to the risk of intrathoracic injury.
Two sutures are routinely inserted, the first to assist closure of the wound after drain removal, usually a mattress suture, and the second, a stay suture to secure the drain. “Purse-string” sutures are no longer recommended due to the less pleasing scar and increased pain whilst in situ.
The catheter position and pneumothorax are then checked with an anteroposterior chest radiograph. The catheter may be removed 24 hours after radiographic evidence that the lung is fully inflated. The drain should be removed whilst the patient performs either Valsalva's manoeuvre or during expiration. Provided aseptic techniques have been used, there is no role for prophylactic antibiotic administration for chest drain insertion.
Vomiting
Postoperative vomiting in patients with intermaxillary fixation was a well-recognised problem. Predisposing factors are blood escaping intraoperatively and postoperatively into the stomach, where partial digestion together with bile reflux creates an irritant stagnant mixture. An additional factor is the emetic effect of opiate analgesics.
Prevention
i) Avoid intermaxillary fixation by using internal rigid fixation.
ii) A 12-16FG nasogastric tube passed at the time of the anaesthetic induction enables postoperative aspiration of gastric contents. The tube is attached to a bile bag to create a closed collecting system for any spontaneous reflux. As the patient is monitored throughout the postoperative night the stomach should be aspirated hourly and the fluid loss noted. Initially flushing the tube with 20 ml water before aspiration prevents the end becoming clogged with clot.
The administration of an antiemetic, e.g. metoclopromide 10 mg intravenously at the end of the operation, and with any required opiate analgesics, reduces drug-induced emesis (up to a maximum of 30 mg/24 hours). Metoclopromide 10 mg intravenously should also be given at any other time if vomiting is anticipated. 5HT antagonists such as ondansetron block the action of 5HT in the intestine and CNS, which also has an antiemetic effect. This is introduced after the administration of metochlopramide. With a fully conscious patient it is often the nasopharyngeal airway that provokes the problem.
Management
The patient who is being nursed in a 45 sitting position should be sucked out immediately through both sides of the nose with a broadcore catheter. The buccal sulci will also require clearing.
Contrary to popular belief, cutting intermaxillary fixation — if used, is neither essential nor the most efficient way of managing the vomiting patient.
Paradoxically, nasal suction is more efficient than opening the mouth and attempting to clear the oropharynx of vomitus in a conscious patient.
5. Iliac Crest Problems
The removal of bone from the iliac crest for orthognathic purposes is becoming less popular. However, the inverted L osteotomy may require a substantial amount of corticocancellous bone to correct a very small mandible.
Postoperative pain is the most frequent complication and can be reduced by drainage and analgesics. Some surgeons leave a fine cannula for infusion of a long acting local analgesic such as bupivacaine (Marcain). It is difficult to be certain if this is of significant value.
If a large graft has been removed near the anterior superior iliac spine, this may fracture with sudden movement once the patient is mobilised (Figure 14.6). No treatment is required apart from reassurance, rest, analgesics and physiotherapy.
Figure 14.6 Fracture at the base of the anterior superior iliac spine with collapse of the preserved iliac crest lid.
6. Catheterisation
Catheterisation is necessary for prolonged surgical procedures, especially where large quantities of fluid have been infused. This is uncommon with orthognathic cases except where there has been unexpected major blood loss. Another occasional indication is the patient, usually male, who has postoperative urinary retention. This may be due to opioid-induced sphincter spasm, diffidence in using a urinal, or a combination of both, leading to gross distension. Any associated agitation will resolve with catheter insertion and bladder drainage and does not need to be controlled with intravenous benzodiazepines.
Technique
As with all separate aseptic procedures, each area must be freshly prepared and the surgeon re-gloved and gowned.
Clean the external genitalia carefully with sterile saline and towel the area. Place a receiver between the abducted thighs. ANo. 14 or 16 Foley catheter is the optimum choice; its retaining balloon can be tested by inflating with air. Note: if there is obstruction, try a smaller gauge (10-12 FG) or a firmer, curved Coudé catheter.
With males the penis is held vertically in sterile gauze. Sterile lubricating gel with lignocaine is instilled into the urethra. After giving the lignocaine a minute to work the catheter is then passed vertically downwards to the lower border of the pubic symphysis. With continued pressure on the catheter the penis is rotated downwards (caudally) so that the catheter may traverse the angle at the penoscrotal junction in the bladder. In cases of prostatic enlargement or stricture this may be difficult and will require expert help.
With females it is important to part the vaginal labia to reveal the external urethral orifice within the vestibule. The inexperienced attack the base of the clitoris, which is above the urethral orifice, with the catheter tip.
Once the catheter is in the bladder, urine will pass into the receiver. Gentle aspiration may be required initially to clear obstructing gel from the tip of the catheter. Push the catheter in maximally and fill the balloon with 10 ml sterile water (always check the balloon volume first); a gentle pull should indicate its retention. Attach the catheter to a collection bag to complete a closed drainage system; monitor urinary outflow, which should exceed 30 ml/h. Remember to change the bag every 24 hours if it is retained. Remove the catheter as soon as possible.
7. Deep Vein Thrombosis
This is a rare event in orthognathic patients, usually occurring unexpectedly in young women. As a precaution, all women should cease taking oestrogen containing contraceptive pills 4 weeks prior to surgery. If this has been overlooked, subcutaneous low molecular weight heparin prophylaxis should be considered, i.e. Dalteparin Sodium 5000 units preoperatively followed by a daily injection for 5-7 days. Both high and low risk patients benefit from elasticated thromboembolic-deterrent stockings being worn during the operation. Any complaint of postoperative calf tenderness must be taken seriously, especially when there is an increase in circumferential measurement and/or local erythema. Lower limb Doppler ultrasonography should be carried out and if this is positive (or not possible) the patient is anticoagulated to prevent extension of the thrombus and embolism.
An oral anticoagulant such as warfarin should also be started at 10 mg/day for the first 3 days, or as guided by your local anticoagulation clinic. Abaseline prothrombin time is recommended prior to anticoagulation if any liver disease is suspected. Subsequent prothrombin times (INR) should be 2-2.5 times normal and taken on the second and third days of treatment and then weekly to confirm a stable ratio. Follow up in the anticoagulation clinic should be organised prior to discharge from hospital. The usual maintenance dose of 3-9 mg is taken at the same time each day for 3-6 months. The patient should continue on daily subcutaneous injections of low molecular weight heparin until full oral anticoagulation with warfarin is established or on daily heparin injections only if pregnant.
8. Fixation Problems
These are infinitely varied but fortunately become uncommon with experience.
i) Infection may occur around screws and plates. Miniature plates are an essential part of the osteotomy and surprisingly in the maxilla rarely get infected. If drainage and a course of antibiotics do not suppress the infection, the plate and screws have to be removed. Similarly, uninfected bone plates may become palpable subcutaneously or submucosally and also require removal.
ii) Incorrectly placed screws and plates may displace the bony parts. This occurs more commonly in the third molar area with the sagittal split operation, but is also with Le Fort I procedures where maxillary displacement can distort the nasal septum. Less commonly plates break. Whenever displacement or loss of control takes place, the patient should be taken back to theatre for correction. Pious hopes that the problem will go away or will be correctable by postsurgical orthodontics always prove to be futile.
iii) The use of screws or buccal plates for rigid fixation of the mandible can create occlusal discrepancies if it is not appreciated that the osteotomy is carried out with the patient anaesthetised and supine. If the condyle is pushed to the back of the fossa when temporary intermaxillary fixation is put on to facilitate the insertion of the bicortical screws or buccal plate, on its release, with the patient conscious and upright, the condyles will tend to recoil downwards and forwards. This is favourable for the Class 2 Division I mandibular advancement but gives a postoperative prognathous malocclusion with the Class 3 setback. To avoid these artefacts (a) the model surgery should be based on a conscious supine centric relation squash bite and (b) the ascending ramus proximal fragment should be displaced backwards for Class 2 advancements but pulled forwards prior to fixation with the Class 3 mandibular setback.
Such problems were less likely to happen with a loose interosseous wire loop at the osteotomy site and prolonged intermaxillary fixation for 6 weeks. This enabled the ascending ramus proximal fragment to achieve an optimum condylemeniscus-fossa relationship by functional adjustment brought about by swallowing and speech.
iv) Disturbed muscular proprioception and intracapsular oedema may also give a transient deranged postoperative occlusion when using rigid fixation. In these cases, light elastics for 7 days will help to restore the occlusion to the planned relationship. The final occlussal wafer is often left in situ even where there is no occlussal problem. This is very uncomfortable for the patient and there is no evidence that it helps. However, if after this elastic “proprioceptive regimen” there still appears to be marked displacement and malocclusion — re-operate.
9. Relapse
Relapse is any unanticipated postoperative change in the planned or achieved dental or skeletal relationships. Most arise from inadequate planning or inappropriate surgical technique. The former have been discussed in Chapter 4 on Planning Data Transfer. The latter may be roughly divided into two overlapping groups: those arising from (1) operative structural causes and (2) postoperative functional causes.
a) Operative Structural Causes of Relapse
Inadequate bone, cartilage or periosteal separation. Osteotomy cuts and soft tissue dissection must provide absolute freedom of movement of the parts and allow effortless repositioning. Tight bone plates will not correct reluctant anatomical components but will cause some malalignment elsewhere. Common sites are as follows.
i) Inadequate separation of the proximal mandibular bone and the medial pterygoid muscle from the buccal plate when doing a sagittal split. A finger firmly inserted to the depth of the split is used to remove the restraining periosteum and muscle fibres, which hold the two cortices together at the lower border.
ii) Inadequate bone removal from the posterior wall of the antrum or separation of the pterygoid plates in a Le Fort I impaction can also create problems.
iii) The untrimmed nasal septum will create a buckling effect and either displace the maxilla and disturb the occlusion, or displace the nose and produce an asymmetric tip deformity, and obstruct the airway. Late correction will require a rhinoplasty.
iv) Where a mandibular osteotomy has been done with the pious hope of eradicating temporomandibular joint pain in a patient with a meniscus displacement, the osteotomy may not only give rise to more pain initially but may create intracapsular adhesions and limited opening postoperatively.
v) Occasionally lower lip sag may follow a bone graft procedure to increase the chin depth by augmentation, or a mandibular forward movement with a genioplasty. It is difficult to be sure whether it is due to inadequate freeing of the periosteal pouch and overlying soft tissues, or failure to re-attach the mentalis high enough on the anterior mandibular surface, or abnormal muscle activity. The last cause would be inadequate orbicularis tone or decreased mentalis elevated activity.
The lip sag should be avoided by the creation of a large loose periosteal pouch to accommodate the enlarged chin, carefully suturing the divided mentalis to the deep muscle fibres on the alveolar surface, and the application of a firm pressure dressing overlying the labiomantal groove. Once formed it can be eliminated in some cases by vigorous exercising of the lower lip, i.e. the lip is actively stretched upwards over the incisor edges. If this fails, it will be necessary to deglove and reposition the soft tissues upwards using heavy polyglycollate (Vicryl) sutures to elevate the soft tissues of the chin.
vi) Tooth damage may occur with the bone cuts of segmental osteotomies, either apically or laterally. Avoid the former by marking the estimated apical site with a shallow bur hole prior to the section. Lateral root damage arises when burs are used interdentally. Only the buccal and lingual (palatal) bone should be cut with a bur and the actual division should be made with a fine osteotome or saw.
Although root damage often appears to be self-limiting and most teeth survive, occasionally the exposed dentine undergoes progressive resorption. An attempt may be made to preserve the tooth by root canal therapy with calcium hydroxide. However, should root loss progress, extraction and an implant or bridge will be required to salvage the situation.
Segmental cuts in the older patient with incipient periodontal disease may also create intractable bony pockets unless anticipated. The cuts must be done carefully with a fine osteotome after prior periodontal therapy followed by postoperative oral hygiene instruction.
b) Postoperative Functional Causes of Relapse
i) The most notorious is the recurrent anterior open bite following attempted correction with a mandibular osteotomy. This will occur in patients with a high mandibular-maxillary plane angle where the low posterior facial height reflects a short pterygomasseteric sling. This is stretched as the mandible is rotated around the fulcrum created by the occluding molar crowns when the anterior teeth are brought into occlusion to close the gap. The inelastic ligaments and the return of postoperative muscular tone may even produce a relapse despite internal fixation. This is avoided by a posterior maxillary impaction equivalent to the anterior open bite to be corrected.
ii) Postoperative tooth movement can be favourable, especially with the spontaneous or assisted closure of lateral open bites. However, unfavourable tooth movements may arise.
· Repositioned lower incisors are proclined by a large or “anteriorly postured” tongue.
· Upper incisors are proclined by the lower lip after a maxillary segmental pushback procedures is carried out on a marked Class II, Division 1 patient without a mandibular forward correction to an edge to edge relationship.
· Continued eruption (occlusal drift) of the lower incisors will follow an anterior segmental setdown unless they are placed in a stabilising contact with the cingula or incisive edges of the opposing teeth.
· Expansion of the maxillary premolar and molar segments may tilt those teeth buccally. Subsequent palatal drift will produce intercuspal contact on closure with the creation of an anterior open bite. Major expansion of the palate should be done surgically with a midline osteotomy to avoid dental relapse.
· Idiopathic periapical and internal resorption may occur in teeth adjacent to an osteotomy cut, even without untoward bur contact. The cause is unknown but may be due to a vascular response to the adjacent surgery.
· Orthodontic depression of lower incisors in adults, before surgery, may cause proclination with alveolar dehiscence and gingival recession. Furthermore, the proclined incisors may then upright spontaneously once fixation is removed.
If, after a considerable input of time and energy if both surgeon and patient, are agreed something has gone seriously wrong with the operative correction — start again!
c) Nerve Damage
i) It is important to warn the patient preoperatively of impaired sensation that may arise in the mental or mylohyoid nerve distribution of the lower lip and chin following a sagittal split or anterior segmental operation, and in the infraorbital area following a maxillary osteotomy. The former usually recovers in 2-6 months, although some patients have a permanent deficit, which is less noticeable if the operation is otherwise successful.
When the inferior dental nerve is exposed and torn during the sagittal split, it may be possible to hold the separated ends together with a 6/0 Prolene suture prior to fixation.
ii) Facial nerve damage with weakness can be localised following external incisions for a subsigmoid (subcondylar) osteotomy but will involve a wider distribution of the facial nerve if it is damaged near its main trunk. This can occur with a sagittal split pushback or an intraoral subsigmoid (subcondylar) operation. The cause is probably traumatic instrumentation. They prognosis is usually very good, with gradual recovery over 6-8 weeks.
iii) The lingual nerve is rarely damaged during an osteotomy. However, persistent impaired lingual sensation after 6 weeks requires open exploration and repair. This is most easily done by removing the overlying sublingual salivary gland.
iv) A rare disturbance is nasal vasomotor hyperfunction, which may occur after a Le Fort I osteotomy. The patient develops continuous rhinorrhoea, which simulates a cerebrospinal fluid leak. The cause is uncertain and may be either loss of sympathetic vasomotor control or damage to the sphenopalatine ganglion with enhanced stimulation. There is no satisfactory treatment.
10. Emotional and Psychiatric Problems
These vary from postoperative depression, often manifested as a refusal to take food or medication by mouth, to more dramatic states. Many patients would be spared a reactionary depressive state if they had been carefully warned of postoperative problems on admission. Good nursing care and attentive surgical staff are the treatment of choice.
Agitation can arise both from intolerance of intermaxillary fixation or simply nasal airway obstruction. Both can now be avoided. However, not only is it essential to clear the nose by inhalations and suction, but always seek an underlying structural obstruction, such as a displaced nasal septum.
Unanticipated anxiety of an alien environment, especially the intensive care unit, may precipitate postoperative psychotic behaviour. This can be controlled by intravenous antipsychotic drugs such as haloperidol, which can later be given orally.
Emotionally unstable individuals, especially those who have a history of body dysmorphic disorder, may also become aggressive and difficult to control. Again, an antipsychotic drug regimen is essential, together with preoperative and postoperative psychiatric advice. Unfortunately some patients get legal aid to express their illogical complaints through a solicitor. It is wise to report the problem to risk management in an NHS hospital who can if necessary provide legal support. With private patients the surgeon will need to seek the advice of their medical defence society.
Dissatisfaction can be avoided by repeated preoperative discussion about the operative procedure, the immediate and late complications and, most important of all, the patient's aesthetic expectations. All these should be recorded.
Finally an explanatory handout of the operation covering common complications is essential.