Procedures To Investigate The Abdomen

Introduction Accurate assessment and investigation of the injured or potentially injured abdomen may be the initial key to successful management of the injured patient. Resuscitation room screening X-rays including plain views of pelvis and chest X-ray may alert the receiving clinician to the possible presence of abdominal trauma. Plain abdominal X-rays may be of benefit in demonstrating gross changes such as damage to transverse processes of lumbar vertebrae or increases in the psoas shadow (suggestive of bleeding) but these signs are inaccurate and should not be relied upon. Further investigations may be non invasive (abdominal ultrasound or computerised tomography) or invasive (paracentesis, diagnostic peritoneal lavage or laparoscopy). Adequate treatment should not be delayed for the purposes of investigation. At times the injury is so obvious (eg penetrating trauma or peritonitis) and the patient so unstable that immediate transfer for laparotomy is the only alternative. Indications for further investigation include, an equivocal abdominal examination, haemodynamically unstable patient (hypotension or drop in haematocrit / haemoglobin level), and altered mental status due to a closed head injury or intoxication with alcohol and/or drugs. Other indications include spinal cord injury and patients who cannot be examined serially due to other diagnostic procedures. Paracentesis (four quadrant tap) Many clinicians will have gained experience of paracentesis in patients with ascites. The indication for paracentesis in trauma is very limited. Paracentesis may confirm an obvious diagnosis of major intraabdominal bleeding but the procedure has a high false negative rate (Credi 1994), and negative findings carry little clinical relevance. Its use should be limited to the situation when a diagnostic peritoneal lavage (DPL, see page 00) cannot be carried out due to time constraints and bedside ultrasound is not available. Paracentesis is contra-indicated when the abdomen is both distended and tympanic possibly secondary to dilated bowel. In this situation a blind tap might perforate or tear bowel and cause leakage of bowel contents under pressure. A distended but non resonant abdomen may well be full of blood although the presence of other fluids such as urine should also be considered (in the event of possible bladder perforation). Procedure Expose the entire abdomen and prepare it with antiseptic (eg povidone Iodine). Choose the site in each of the 4 quadrants of the abdomen (Fig 39.1). Areas which are dull to percussion may contain fluid/blood. Old scars should be avoided, because bowel may be adherent internally. The site of puncture should be lateral to the rectus abdominis muscle to avoid injury to the epigastric vessels. Infiltrate local anaesthetic (1% Lignocaine with adrenaline) in each site. In extreme situations the use of local anaesthetic may be deferred.

 

Attach a 20mL syringe to an 18 gauge beveled needle. Insert the needle into the abdomen, aspirating once the needle has penetrated the abdominal wall. Notes A positive result is obtained when non clotted blood is aspirated. This is an indication for a laparotomy. Penetration of non dilated bowel by the (18G) needle is usually non consequential because it should seal quickly causing no leakage. Diagnostic peritoneal lavage (DPL) Diagnostic peritoneal lavage is used in many units as a first line investigation for possible or suspected intra-abdominal bleeding. It is extremely sensitive to the presence of intra-peritoneal bleeding, being able to pick up just 20ml of blood (Day 1992) (Sensitivity 85-98%), but because of this laparotomies may be carried out for minor injuries which would not have in themselves needed surgery leading to a non therapeutic laparotomy rate of between 20 - 40% (Fryer 1991, Bilge1991). Relative contraindications to DPL include near term pregnancy (DPL should be carried out supraumbilically in this situation), presence of a coagulopathy, cirrhosis, and multiple prior abdominal operations. Procedure Prepare the patient: Insert a urethral catheter and also a nasogastric tube if there is a chance that the stomach may be full. Prepare the abdomen with antiseptic (eg povidone Iodine) and drape aseptically. Open technique for DPL. Infiltrate Local Anaesthetic into the selected site (usually below the umbilicus or supraumbilicus in pregnant patients). Make a 4 – 5 cm midline incision through skin and subcutaneous tissue till the linea alba is revealed. Incise the linea alba to expose the peritoneum. Secure the peritoneum with haemostats and incise to achieve access to the peritoneal cavity. Insert a peritoneal dialysis catheter into the peritoneal cavity advancing it towards the pelvis. Attach a syringe to the catheter and aspirate. If there is no blood in the aspirate, the fascia should be closed using Vicryl sutures. At least 1L of warmed normal saline is then instilled via the catheter into the peritoneal cavity. The catheter should be attached to an empty peritoneal dialysis bag.

The abdominal cavity should then be agitated by gently rolling the patient from side to side. After 5 minutes place the bag below the level of the patient and allow the instilled fluid to drain. At least 750ml of dialysate fluid should be collected and sent for analysis. Notes Red cell and white blood cell counts should be carried out on the fluid collected together with Amylase and Bilirubin concentration. Microscopy is also performed along with a Gram stain. A DPL is deemed positive if blood or bowel contents are aspirated from the abdomen. It is also determined to be positive if on analysis of the dialysate, greater than 100,000 RBC/mm3 or 5000 WBC/mm3 are found. If laboratory analysis of the returned dialysate is likely to be delayed, the inability to read newsprint through the fluid bag is often regarded as “positive”! Presence of bile, bacteria or faecal matter in the dialysate suggests bowel damage. Variations exist on the “open technique” as described above. These include the “semi-open technique” and the “closed technique”. The semi-open technique involves blind insertion of a catheter through the fascia, preperitoneal fat and peritoneum after the skin and subcutaneous fatty tissue is incised. In the closed technique, an 18 gauge needle is passed into the peritoneal cavity and a guidewire passed through the needle. A dilator is then introduced over the guidewire and removed. A catheter is then passed over the guidewire in the peritoneal cavity after which the guidewire is removed. In both cases the remainder of the procedure follows the technique described above. If necessary the catheter may be left in situ in order to allow repeat lavage after a suitable time interval. DPL should not be carried out prior to planned abdominal ultrasound or CT scanning in order to reduce risks of false positive findings on scanning. False positives on DPL may occur from abdominal wall bleeding from a traumatic catheter placement and from pelvic fractures.

Laparoscopy Although laparoscopic investigation was first mooted in 1980 (Sherwood et al), the revolution in general surgical laparoscopy of the 1990s has led to only a relatively limited use of the technique for both investigation and sometimes treatment of the injured abdomen. Laparoscopy has been used in both blunt and penetrating trauma, although it may be risky if diaphragmatic injury is a possibility because of the effects of the pneumoperitoneum on the pleural cavity. It is, however an excellent method of accurately identifying and assessing such injuries. “Bedside” use of laparoscopy under local anaesthetic is possible although most reports have concerned general anaesthetic operating room procedures.

This technique should only be carried out by experienced surgeons with a laparoscopic practice in the non injured abdomen. The advantages of laparoscopy are that intra-abdominal bleeding may be identified, minor injuries may be identified without recourse to full laparotomy and some minor therapeutic procedures may be carried out without the need to inflict a major laparotomy scar. Anterior penetrating injuries can be evaluated well. (Rossi et al). Laparoscopic treatment may lead to less postoperative chest complications and earlier discharge form hospital. The drawbacks to the procedure are 1.

This is a highly invasive procedure.

2. The retroperitoneum and some of the bowel are not amenable to easy inspection 3. The patient should be haemodynamically stable At present the use of laparoscopy for assessment of the injured abdomen should continue to be evaluated in experienced centres in trial settings to allow full assessment of safety and accuracy. (Rossi 93, Leppaniemi 96, Zantut 97)

Abdominal ultrasound (ultrasonography) Abdominal ultrasound can identify both free fluid (more than 70ml) in the abdominal cavity with a sensitivity of over 95% and also solid organ injury although with less accuracy. Ultrasound examination is a non invasive procedure and can be carried out at the patient’s bedside or in the resuscitation room. The procedure can take only about 2-3 minutes to carry out and can be repeated as necessary. For this reason ultrasound examination is becoming a first line investigation in many centres (Bain 1998), especially those dealing with paediatric trauma. (Rossi 93, Akgur 93, Corbett 2000) The major drawback of the procedure is that it is observer dependent, requiring an operator with experience of both the scanning equipment and experience of abdominal scanning. Use of colour doppler scanners in the assessment of internal organs may improve accuracy (Nilsson 99) by demonstrating non perfused tissue, but this practice has not yet gained wide enough use to establish the routine need for such equipment in the recovery area. Some centres are now introducing Focussed Abdominal Sonography for Trauma (FAST) where limited structured examinations are carried out by non radiologists to identify free abdominal fluid. Such identification equates with the discovery of blood on DPL. Initial results of studies looking at the accuracy of FAST appear encouraging. (Boulanger 99, Yeo 99, Lingawi 2000) Because ultrasonic evaluation of the injured abdomen relies on the presence of free blood for a positive result, very early examination may lead to false negative findings. Re-examination after a short period of resuscitation is worthwhile in case of continuing intraperitoneal haemorrhage. Hand held scanning devices are being developed, and may lead to greater versatility in the use of trauma ultrasonography. (Wherry 98) The role of computerised tomography (CT) scanning and magnetic resonance imaging (MRI) in

trauma CT scanning in trauma CT scanning has become established as a diagnostic tool of choice in the assessment of head trauma and pelvic fractures. It may also be invaluable in the assessment of abdominal, thoracic and spinal injuries. As with MRI scanning CT scanning requires patients to be haemodynamically stable for a period of time. Spiral CT scanning has allowed the scan times to be reduced, but the patient still needs to be stable enough for transfer to a CT suite. C

CT scanning in abdominal trauma

CT scanning of the injured abdomen is often claimed to be the “gold standard” in abdominal trauma investigation (Corbett 2000) because it is not only sensitive, but also has a high specificity. In addition to being able to identify the presence of intra-abdominal fluid , individual organ damage can be identified. Retroperitoneal trauma may be identified and trivial trauma not requiring laparotomy may be diagnosed as such. Active decisions can be made regarding non operative treatment of these patients with view to repeat examinations as necessary. More information can be gained with the use of both oral and IV contrast agents. The oral agent (Gastrograffin) can be drunk sufficiently prior to the scan by the patient or instilled via a nasogastric tube. This is not always practical in severely injured patients. IV contrast agent may be injected at the time of the scan. This helps not only to identify the major vascular structures, but also to confirm the vascular integrity of major abdominal organs such as the liver or kidneys. Individual organ injuries can be initially assessed and if necessary, repeatedly monitored., allowing closely controlled conservative management such as non operative treatment of paediatric splenic injuries. Patients with stab wounds to the back and flank can be evaluated with triple contrast enhanced CT Scans. Retroperitoneal structures can be evaluated with the administration of contrast material orally, rectally and by IV. The role of CT scanning in head trauma CT scanning is the diagnostic modality of choice in the evaluation of head trauma. The presence of intracranial haemorrhage is usually well demonstrated . CT scanning can also detect oedema, mass effects (hemispheric shifts) on brain matter, brain infarction, foreign bodies, skull fractures and hydrocephalus. A fresh bleed in the brain usually appears white on scanning, while cerebrospinal fluid looks black. Oedema in brain matter appears darker than non-oedematous brain. Most studies in head trauma do not need contrast enhancement unless a tumour or abscess is suspected. Normal scan findings despite severe neurological changes would normally require serial scans.

Findings in epidural haematoma An epidural haematoma can occur due to skull fractures, which classically occur in the petrous temporal bone causing laceration of the posterior branch of the middle meningeal artery. The injury causes stripping of the dura from the inner table of the skull, creating a potential space into which the lacerated artery bleeds. The expanding extradural haematoma can cause compression of the brain. The classical finding on CT scanning is a biconvex (or lentiform) lesion, which does not cross suture lines.

Findings in subdural haematoma Subdural haematomas are common in trauma. They are caused by injured bridging veins. These normally drain blood from the cortex to the dural sinuses. Lesions may be small or may present with catastrophic symptoms. Subdural haematomas are classically seen in the elderly. The findings on CT scanning include crescenteric collections, which conform to the surface to the brain. Other CT findings include oedema, brain shift and loss of gyrae. Repeat CT scans with enhancement and coronal views can often pick up atypical haematomas.

Findings in subarachnoid haemorrhage Subarachnoid haemorrhage is usually detected on a non-contrast CT scan. It is commonly detected in the basal cisterns.

Other head injury CT scanning has a crucial role in the evaluation of Orbital fractures with the detection of haematomas (and subsequent evacuation under CT guidance). CT scanning has a role in the evaluation of maxillo-facial fractures. 3-D reconstruction of axial sections can be used to accurately elucidate mid face fractures. Diffuse axonal injury can also be picked up CT scanning although MRI is a better diagnostic tool for this purpose.

Role of CT scanning in traumatic injury of the larynx CT Scanning is particularly useful in the detection of fractures of the thyroid cartilage and other injuries of the larynx including haematomas, arytenoid cartilage dislocation and injuries to the trachea.

Role of CT scanning in injuries of the spine CT scanning of spinal injuries provides good visualization of soft tissue damage. There is also better visualization of the C7-T1 junction that might be obtained in standard radiographs. The scans are usually thin cuts in the axial plane. MRI provides better images of the spinal cord while CT scanning is preferred for bony tissue.

The cervical spine should be protected and immobilized in a hard cervical collar if the level of damage to the spine is unknown.

Role of CT scanning in trauma to the chest Thoracic CT scanning is more accurate than plain chest X-rays in demonstrating trauma in the chest. Chest wall, pulmonary, mediastinal or pulmonary damage may be accurately assessed. CT scanning is particularly useful when pulmonary contusion, pneumomediastinum or haemomediastinum is suspected. In addition diaphragmatic and pleural injuries may be visualized by CT scanning. In the case of suspected esophageal injury, CT scanning can be used to detect signs of mediastinitis. Intrathoracic fluid collections may be drained under CT guidance (by experienced interventional radiologists). In the case of aortic injury, CT scanning has made rapid advances and in conjunction with transoesophageal echocardiography is becoming important in the evaluation of blunt injury to the chest (Patel et al. 1998). However thoracic aortography remains the reference standard for the diagnosis of aortic injury.

Role of CT scanning in pelvic trauma CT scanning has become an invaluable tool in the assessment of pelvic trauma. It is particularly good for imaging the sacroiliac joints and the sacrum itself and may also demonstrate femoral head or acetabular fractures, joint instability, and pelvic ring disruption.

Magnetic resonance imaging in trauma There are potential roles for MRI as a diagnostic tool in trauma. A major advantage of MRI is that there is no need for a contrast agent. MRI is particularly useful in injuries to the spinal cord and vascular injury. Another advantage is the ability to obtain images in other planes such as sagital and oblique. There is a need for a cooperative patient, ideally not connected to monitoring equipment, which may cause interference with the scanner itself. Other problems include the presence of pacemakers or prostheses in the patients, which precludes the use of MRI. It is speculated that in the future there might be a role for MRI in assessing aortic injury, myocardial injury, and brain or spinal cord trauma. Local wound exploration for stab wounds Local exploration of stab wounds is carried out to determine the end point of the tract. The following procedure is not appropriate for assessment of gun shot wounds. The critical determinant is whether the posterior fascia has been penetrated (Markovchick et al. 1985). If there has been no penetration then the patient can be discharged with local wound treatment. The decision to proceed to laparotomy is more

complex, with some surgeons choosing to operate with evidence of fascial penetration while others opt for laparotomy only on evidence of peritoneal penetration (Cameron and Civil 1998). There is consensus however, on the decision to proceed to a laparotomy if there is any indication of peritonism or haemodynamic instability.

Procedure: The area around the wound should be prepared with antiseptic (eg povidone Iodine). The wound should then be infiltrated with local anaesthetic (such as 1% Lignocaine with Adrenaline). The wound should be lengthened with a scalpel along its longitudinal axis and exposed with surgical retractors. Exploration of the wound should be continued until the end of the tract can be seen or if evidence of penetration of fascia or peritoneum is obtained. Notes A negative test is obtained when the tract is seen to end in subcutaneous tissue. A positive test is obtained if in abdominal stab wounds the posterior rectus fascia or transversus abdominis fascia is penetrated. Positive test criteria for lower chest wound involves a penetration of the intercostal muscles in the mid axillary line below the 5th intercostal space. Exploration of lower chest wounds may result in an iatrogenic pneumothorax. If on local exploration the end point of the wound cannot be determined, a peritoneal lavage may then be carried out for lower chest wounds, anterior abdominal wounds and anterior flank wounds. A CT scan is recommended for posterior flank wounds and back wounds. Urinary catheters (Indwelling Catheter or IDC) Catheterization of the bladder is usually performed in trauma to monitor urine output and to relieve urinary retention. It is also performed prior to surgery (for the same reasons) and also used to obtain urine for analysis. Other indications include decompression of the bladder prior to a diagnostic peritoneal lavage, and on the discovery of haematuria to diagnose trauma to the urinary tract. Insertion of a catheter should be avoided if there is any evidence of urethral injury such as the presence of blood on the urethral meatus, and scrotal or perineal haematomas. If the prostate is found to be “high riding” on rectal examination or in the presence of a complex pelvic fracture a IDC should also be avoided. Infection of the lower urinary tract is a relative contraindication.

The most commonly used catheter is the Foley in sizes 16 to 18 F. This is a double lumen tube with the larger lumen draining urine. The smaller lumen inflates the balloon. The size of the balloon should be noted prior to insertion. Other catheters include Straight (Robinson) catheters, coudé catheters (which has a curved tip and is used if an obstruction is found), and three way bladder irrigation catheters. Procedure in the male Position the patient supine. Aseptic technique should be used. Gowns and sterile gloves should be worn. Materials needed include a Foley catheter (size 16 to start with), standard sterile dressing pack, aqueous chlorhexidine, sterile drapes and sterile gauze swabs with plastic forceps, lignocaine gel in a syringe and nozzle, and a standard 10ml syringe (to inflate the balloon). A collection bag should be available to connect up to the IDC. A sterile drape with a hole cut in the middle is used with the shaft of the penis threaded through the hole. The penis is held by the left hand in a right handed person (and vice versa in a left handed person) and the foreskin retracted in uncircumcized males. The right hand remains sterile while the left hand is now considered non-sterile and should not touch the catheter. Swabs soaked in aqueous chlorhexidine are used to clean the glans. Each swab is used only once. At least 4 – 5 swabs should be used in the manner described. The lignocaine gel is injected into the urethra with the use of the special nozzle. If the patient is awake he should be warned of a slight stinging sensation. If there is no urgent requirement for immediate catheterization in a conscious patient a delay of 2 –3 minutes at this stage will allow the local anaesthetic to take more more effect. The penis is first held perpendicular and the catheter is inserted gently advancing without forcing the passage at any stage. If any resistance is encountered the penis shaft should be maneuvered to the horizontal plane first and then in other directions with gentle pressure exerted until the catheter passes to its hilt. When the catheter enters the bladder there will be a gush of residual urine (the volume of which should be measured). Continue to pass the catheter till the hilt. The balloon should then be inflated (noting the balloon size of the catheter BEFORE insertion) with normal saline or sterile water. Always ask a concious patient if he is experiencing any pain during this step. If excessive pain is experienced then this is an indication that the balloon might still be within the prostatomembranous urethra.

The catheter should then be withdrawn until it catches against the bladder neck. The foreskin should be replaced. The IDC should be connected to the collecting bag. Procedure in the female As above with the following points of difference; Wash the labia majora and labia minora with gauze swabs soaked in aqueous chlorhexidine in a anteroposterior direction with each swab (grasped with forceps) being used in one downward motion only. The labial folds should be held apart with the left hand in a right dominant person. The left hand is hence considered non-sterile and should not touch the catheter. The catheter should be lubricated in the lignocaine gel. There is no need to inject the gel into the urethra. Notes As a general rule of thumb if resistance is encountered, a LARGER size catheter should be tried. Other types of catheter are designed for prostatic obstruction. Consultation with a Senior Urology resident/registrar is recommended, to exclude the need for insertion with a catheter introducer or even a suprapubic catheter. Consider the presence of a female chaperone if the catheter is to be inserted in a female patient by a male health professional. If the catheter cannot be inserted consider urethral oedema from multiple insertion attempts, or removal of the IDC without deflating the balloon as a cause. Other serious causes include carcinoma of the prostate, urethral stricture or urethral diverticulum. False passage is also a rare occurrence. Urethral oedema is countered by using a smaller catheter (only indication for a smaller catheter) while a coude catheter or a supra pubic catheter considered in cases of severe retention. Complications that can arise from the insertion of a urinary catheter include infection of the urinary tract (urethritis, epididymitis, bacteraemia), trauma (false passage, stricture), paraphimosis and haemorrhage. Nasogastric tubes The primary use of nasogastric tubes in trauma is to decompress the stomach in order to prevent aspiration of gastric contents. A secondary use is to exclude the presence of blood which otherwise might signify upper gastrointestinal trauma.

The use of a nasogastric tube should be avoided when there is trauma to the face, or neck. A fractured cribiform plate can result in the nasogastric tube tracking into the cranial vault. An orogastric tube is an alternative in such a situation. With injuries to the neck, damaged vessels can rupture and bleed if there is an increase in intrathoracic pressure induced by coughing or vomiting which in turn is caused by the insertion of the nasogastric tube. There are various types of nasogastric tubes with single or double lumens. If the tube is placed beyond the pylorus it can be used for feeding in patients with depressed level of consciousness. Larger diameter lumen tubes are used for decompression while smaller or fine bore lumen tubes are used for feeding purposes. Procedure The tube chosen is lubricated with lignocaine. With the patient supine the tube is inserted heading posteriorly. It is important that the tube is not guided in a superior direction. The patient is asked to make vigorous swallows as the tube passes through the pharynx and oesophagus. The position of the tube can be confirmed by injecting air through the tube and auscultating over the stomach. Alternatively, gastric contents may be aspirated and the acidity checked on pH indicator paper. An X-ray confirming the position of the NG tube may be requested. Notes On insertion the naso-gastric tube can enter the trachea or can curl up on itself in the mouth. Such situations are characterized by a failure to hear the air which is injected, or a failure to aspirate any stomach contents. In this case the tube will have to be removed and a new one inserted. Nasogastric tubes can be blocked by debris or blood clots. Regular flushing of the tube may prevent blockage and subsequent vomiting with aspiration of stomach contents into the lungs. Chest tube (Closed tube thoracostomy) Chest Tubes are used to drain air (pneumothorax), blood (haemothorax), pus (empyema) or fluid (pleural effusions) from the pleural cavity. In the case of a pneumothorax, a chest tube is life saving. In trauma, the decision to insert a chest tube can be made clinically with the findings of shortness of breath, reduced air entry and increased percussive note. Radiographs of the chest should be ordered to confirm the presence of the pneumothorax. The finding of hypotension and tracheal shift from the midline should alert to the possibility of a tension pneumothorax, which should be treated immediately with a needle thoracocentesis. The chest tubes are connected to an underwater drain and might be left to suction drainage or gravity drainage.

Procedure The site of insertion is usually the fifth or sixth intercostal space in the midaxillary line. The patient can be positioned with the arm (of the affected side) raised and fingers placed behind the head. The head should be slightly elevated and the body of the patient tilted away slightly with a pillow. Tubes should not be inserted through wounds (Fig. 39.2). The skin should be prepared with antiseptic (eg povidone Iodine) and sterile drapes. The site chosen for insertion should be anaesthetized with lignocaine taking care to infiltrate the local anaesthetic to skin, intercostal muscles, and pleura. An incision (4 – 5 cm) is made over the intercostal space below the chosen site. Using a curved haemostat, a tunnel is made to the chosen intercostal space. The curved haemostat is guided to the upper edge of the rib (Fig. 39.3a). This creates a cover, which occludes the hole created when the tube is removed. The intercostal muscles are dissected over the selected rib and opened to expose the parietal pleura. The parietal pleura over the rib is punctured (associated with a rush of air) and a gloved finger is inserted. A sweeping motion with the finger confirms that the pleural space has been reached and that any adhesions are removed. The finger can also be used to feel the diaphragm and detect if there is a diaphragmatic tear. The finger is then used to guide the chest tube (size for adults from 28 to 32 Fr or children 16 to 24 Fr) into the pleural space. Then using a curved forceps (Fig. 39.3b) over the distal end the tube is guided apically for a pneumothorax or posterolaterally for a haemothorax. The tube should be clamped at this stage. The tube is then observed for “fogging” with expiration, which is an indication of correct placement. The tube is connected to the underwater drain, unclamped and observed for bubbling and “swinging” of the fluid. The fluid should “swing” (fluid column variation) with each respiration. If the fluid column does not swing, advance the tube further or withdraw a little. Ask the patient to cough and look for bubbles in the column. If there is no movement in the column despite these measures, the tube will need reinsertion. The tube should be secured to the chest wall with a suture (2-0 Silk or nylon) and the incision dressed. Obtain a chest radiograph to determine the position of the chest tube. Notes Removal of the chest drain first involves removing the dressing and sutures. The patient is then asked to

inspire deeply and hold, while the tube is rapidly removed. A gauze dressing should then be placed over the wound and a mattress suture used to close it. A plain chest radiograph should then be performed. Administration of prophylactic antibiotic in patients who receive a chest tube lowers the rate of infective complications (Gonzalez and Holevar 1998). If there is persistent bubbling or a failure of re-expansion, ensure that all the holes of the intercostal catheter are in the pleural cavity. In addition, the tube should be checked to ensure that it is not kinked. Other possibilities include loculation of air, or an airleak fom traumatised lung leading to a bronchopleural fistula or a ruptured oesophagus. Central venous catheterization Central venous access following trauma can be life saving for resuscitation purposes. Other indications for central lines include central venous pressure monitoring, pacemaker insertion and infusion of irritant or concentrated solutions such as dopamine or hyperosmolar saline (Stevenson 1988). The use of a guidewire through needle followed by the catheter (also known as the Seldinger Technique) has made central venous access commonplace and safe. Central venous access can be obtained via the subclavian vein, and the internal jugular vein. Contraindications to insertion include distorted local anatomy and an agitated patient.

Subclavian vein access Access to the subclavian vein allows the measurement of the central venous pressure and subsequent catheterization of the pulmonary artery. It also provides direct access to the superior vena cava and allows easy access to the subclavian vein. There is however an increased risk of pneumothorax and phrenic as well as brachial plexus trauma.

Procedure (infraclavicular approach) (Fig 39.4) Aseptic technique is used for this procedure. The patient is positioned in the Trendelenburg position and the skin widely prepared with antiseptic (eg povidone Iodine). The skin and the periosteum of the clavicle is anaesthetized with lignocaine (1%). With one finger placed on the suprasternal notch as a reference point the needle is inserted below the clavicle (at the junction of the medial third and the middle third of the clavicle) and guided towards the finger placed on the reference point. As the needle advances, the plunger on the syringe is withdrawn until blood is aspirated. When free blood flow is achieved into the syringe the needle is advanced a further 1mm, and then the

guidewire is advanced slowly. If the guidewire inserts without any resistance, the needle is removed and an incision made with a skin knife. A dilator and a catheter sheath are inserted into the incision over the guidewire. The dilator may be removed before insertion of the catheter (in standard catheters, however in those with an introducer sheath, the catheter may be passed over the dilator). The catheter is then advanced over the guidewire into the subclavian vein. Free backflow of blood into a fluid bag connected to the catheter which is lowered below the bed is an indication of a properly placed catheter The supraclavicular approach is an alternative (Fig 39.4). The insertion point being 1 cm posterior the clavicle and 1 cm lateral to the sternocleidomastoid (clavicular head) (Terracina 1994). The needle is aimed towards the contralateral nipple and the rest of the procedure is as described above. Problems that can arise with the subclavian vein catheterization include pneumothorax, arterial puncture and damage to the superior vena cava (which can be life threatening). Internal jugular central venous access The technique used is essentially similar to the technique described above. The central approach uses the two heads of the sternocleidomastoid as an anatomic landmark. The advantages of this procedure include a lower rate of malposition, and a lower incidence of pleural puncture. However it has a higher failure rate than the subclavian catheters Insertion is usually in the supraclavicular triangle, the apex of which is formed by the two heads of the sternocleidomastoid muscle (Fig 39.5). While palpating the carotid pulse with the free hand and retracting it away from the insertion site, the needle is directed at an angle of 40 degrees aiming for the nipple on the same side. The needle should not be advanced more than 4 –5cm for fear of causing a pneumothorax. Once the vein is accessed the procedure is followed as described above. In addition to the central approach to the internal jugular vein there is also an anterior approach and a posterior approach. The anterior approach uses the midpoint of the medial border of the SCM. The posterior approach utilizes the lateral border of the SCM at the level of the apex of the 2 heads of the SCM aiming the needle towards the sternal notch.

Femoral vein access

This may be used for resuscitation purposes. The anatomic landmark is the femoral artery with the vein lying 1 cm medial to the arterial pulse and below the inguinal ligament. The technique of insertion is largely the same as that described above. The landmarks for the femoral vein are depicted in Fig 39.6.

Notes Complications from central lines are numerous, ranging from the already mentioned (pneumothorax, haemothorax and damage to vascular and neural structures), to tracheal perforation, sepsis, cellulitis, osteomyelitis, air embolus, pericardial tamponade, arteriovenous fistulae, thrombosis of the superior vena cava, arrhythmias, and ascites (Terracina 1994).

Saphenous cutdown A cutdown may become necessary for the resuscitation of patients. It is also useful in obtaining access to the peripheral venous system in people who might have difficult to cannulate veins. The long saphenous vein may be used for cutdowns. Procedure The site of the cutdown (e.g.: 1 cm anterior and proximal to the medial malleolus) is prepared with antiseptic (eg povidone Iodine) ointment and surgical drapes. The skin is anaesthetized with local anaesthetic (1% lignocaine for example) A transverse incision is made and the subcutaneous fat and tissue is retracted longitudinally. The vein is isolated and secured with forceps. At this point 2 sutures (silk) are slung under the vein with the distal suture tied off and the proximal suture looped and held with tension. A small incision is made in the vein and a catheter is inserted into this venotomy. Other sites for cutdowns include: The proximal long saphenous vein 5 cm below the inguinal ligament using the femoral artery as a landmark (vein is medial to the artery). Antecubital fossa. It is best to choose a proximal site with the basilic vein (2 cm proximal and 2 cm medial to the medial epicondyle) being the best option (to avoid damage to the median nerve and the brachial artery). The cephalic vein (which is 2 cm proximal and medial to the lateral epicondyle).

Arterial catheters Arterial catheters are primarily used to obtain frequent blood samples (such as frequent arterial blood gases sampling), and to allow continuous blood pressure monitoring (which is particularly useful in the haemodynamically unstable patient.), Arteries that are most commonly chosen for catheterization include the radial, and femoral, However use of the axillary, dorsalis pedis and brachial arteries has been documented. The use of the latter arteries is more problematic.

Procedure There are three ways described of which 2 utilize a catheter over a needle approach and a third which is a guidewire passed through a needle, followed by a dilator and catheter (modified Seldinger) method as described above. The catheter over needle method: The site of insertion is carefully chosen (by palpation of the maximum pulsation). The site is prepared with Betadine, sterile drapes and local anaesthetic (which helps counteract vasospasm) The needle and catheter is advanced into the skin at an angle of 45 degrees. The needle is guided further until there is a flashback (with pulsation) into the apparatus. At this point either of two methods can be used. The first method involves advancing the catheter and the needle through the superior and inferior walls of the artery. The needle is then withdrawn, and following this the catheter is gradually withdrawn till pulsatile flow results. At this point the catheter is advanced through the artery. The alternate method is similar to cannulation of a peripheral vein. After the skin is punctured at an angle of 45 degrees, and pulsatile flashback is obtained, the apparatus is dropped to an angle of 10 degrees and advanced 2 mm, after which the catheter is advanced into the artery. After the catheter has been introduced into the artery, it is connected up to an infusion of heparinized saline and sutured into position.

Notes Complications of this procedure include haematomas (most commonly), cellulitis, nerve injury and embolus. Arterial lines appear to have a lower infection rate than central lines (Samsoondar et al. 1985). The brachial artery appears to have a higher complication rate when compared to the radial artery.

The Allen’s test should be performed on elderly patients. Patients with a positive Allen’s test have an increased risk of ischaemia due to ulnar artery insufficiency. The test involves simultaneous occlusion of both the radial and ulnar arteries. The patient is asked to open and close their hands till there is palmar pallor. At this point the ulnar artery is released and a palmar “blush” is looked for. If this is delayed (longer than 7 seconds) or fails to occur then the test is deemed positive.