Membrane sieving coef \201 cient (SC) During UF, the driving pressure jams solutes, such a s urea and creatinine, against the membrane. The SC determines the amount of solute that pa sses through the pores of the membrane. The SC is calculated by the ratio of the con- centr ation of the solutes in the \201 ltrate to that in the plasma. An SC of 1.0, as is the ca se for urea and creatinine, demon- strates complete permeability and a value of 0 total imp er- meability. Molecular size (<12Da) and \201 lter porosity are the major determinants o f SC. During continuous treat- ments, a minimum urea clearance of 30ml/h/kg (2.8l/h in a 70 kg patient) is required. Techniques Slow continuous ultra \201 ltration (SCUF) Blood is driven by a pump through a highly permeable \201 lter via an extracorporeal circuit, using venovenous access. The ul trafiltrate produced during membrane transit is not replaced and it corresponds to weight l oss. It is used only for \202 uid control in overloaded patients Circuit blood \202 ow: 100 \200\223250ml/min. Ultra \201 ltrate \202 ow: 5 \200\22315ml/min. Continuous venovenous haemo \201 ltration (CVVH) CVVH is similar to SCUF above except that the ultra \201 l- trate produced during membrane transit is partly or com- pletely replac ed to maintain intravascular volume control. Replacement \202 uid may be delivered before , after or on both sides of the \201 lter (pre- or post-dilution). Clearance for all solu tes is convective and equals the UF rate. Circuit blood \202 ow: 100 \200\223250ml/min. U ltra \201 ltrate rate: 15 \200\22360ml/min. Continuous venovenous haemodialysis (CVVHD) In CVVHD, blood is driven through a low permeab ility dia- lyser via an extracorporeal circuit in venovenous mode and a counter-current \202 ow of dialysate is delivered on the dia- lysate compartment. The ultra \201 ltrate pr oduced during membrane transit corresponds to the patient \200\231s weight loss. Solute cle arance is mainly diffusive, and ef \201 ciency is limited to small solutes only. Circuit b lood \202 ow: 100 \200\223250 ml/min. Dialysis \202 ow: 15-60 ml/min. Continuous venovenous haemodia \201 ltration (CVVHDF) This is a technique where blood is d riven through a highly permeable dialyser via an extracorporeal circuit in veno- venous mod e and a counter-current \202 ow of dialysate is delivered on the dialysate compartment. T he ultra \201 ltrate 70 A SHORT Peritoneal dialysis (PD) There are reports of the \201 rst PD being performed in the mid 18th century; however, it was not until the 1920 \200\2231930s that the treatment was re-introduced experimentally f or acute renal failure. It began to \201 nd some favor in the late 1940s, but was dogged by the problem of peritonitis and access problems. Since the 1970s, continuous ambulatory p eritoneal dialysis (CAPD) has been a common form of ESRD therapy, particularly for those wi th some residual renal function for whom it can be used for many years or where there are c ontraindications to anticoagulation. Many patients ultimately have to move to haemodialysis in order to achieve adequate control of azotaemia. However, prior to this, intermittent PD was a relatively common method used for the management of acute renal failure or as a (les s than ideal) bridge until a place was found on a chronic haemodialysis program. Other than the lack of need for anticoagulation, the main advantages of PD is that the peri- toneum i s a natural semi-permeable membrane and that the process can be continuous. CAPD allows nea r normal patient mobility These frequently caused leakage, infection was common and the risk of visceral damage high, but nowadays silastic catheters based upon the design of Tenckhoff and Schechter are used which are tunneled subcutaneously and have Dacron cuffs placed subcutaneously. These may be inserted via a trochar and cannula, mini- laparotomy or minilaparoscope even at the bedsid e. The proper positioning of the catheter is essential to ensure ef \201 cient drainage an d function of the catheter. Simple issues such as constipation may signi \201 cantly affec t catheter function. Previous abdominal surgery with the likelihood of multiple adhesions i s a relative contraindication for PD Techniques PD is carried out by \201 lling the peritoneal cavity with sterile pre-prepare d dialysate fluid. The peritoneal fluid will achieve solute equilibration with the plasma w ater in 4 \200\2235h, although the optimum dwell time for maximum \202 uid removal using dextrose as the osmotic agent is 2 \200\2233h. The \202 uid is then drained and replaced with fresh dialysate. A single \201 lling and draining of the peritoneal cavity is called a cycle. The commonly used CAPD popularized in the late 1970s for ESRD management uses lon g dwell times and 4 \200\2235 cycles per day, 7 days per week. The patient drains and re \201 lls the peritoneal cavity, taking 30 \200\22340min, at intervals throughout the day. T he ef \202 uent bags are weighed to determine the volume of \202 uid removed and the con centra- tion of osmotic agent adjusted to keep the patient \200\231s \202 uid balance neu tral. Some patients use machines that cycle on a shorter time basis through the night. Thes e remove the need for inconvenient bag changes, warm the dialysate and can be programmed fo r targeted \202 uid removal. The abdo- men can be left empty or full throughout the day. The method used will depend upon the method availability, individual circumstances and the wishes of the patient. Peritoneal membrane structure and solute transfer The three-pore model of the peritoneal me mbrane accounts for \200 the measurable, but low, rate of transfer of proteins through a small number of large pores >15nm some convection with solvent drag (osmotic gradient) through water channels, 0.5nm ( aquaporins) diffusive solute movement (concentration gradient) through the large number of 4nm pores allowing small solute and water passage. Solute transportation is closely linked to the capillary supply to the visceral and parieta l peritoneal membranes, and the effective surface area for solute and \202 uid exchange i s less than the anatomical area of the peritoneal membrane. The rate-limiting steps for sol ute transfer are therefore the permeability of both the peritoneal capillaries and the per- meability and size selectivity of the peritoneal membrane. There is considerable variation between individuals for these factors, which is further signi \201 cantly affected by in \202 ammation. Dialysate General composition PD \202 uid contains sodium, chloride, calcium and magne- s ium. The concentration of these can be adjusted, although this is primarily used for calciu m. Buffer Lactate has been the standard for many years, but is being replaced by or combined w ith bicarbonate. Access A catheter is used to provide access to the peritoneal cavity. Originally these were relatively rigid and introduced blindly over a stylet directly through the abdominal wall. Osmotic agent Traditionally dextrose has been used in different concen- trations \200\224st andard, 1.36% (350mosm/kg), or high osmolar- ity, 3.86%, depending upon the quantity of \202 uid removal required. The glucose used in CAPD may make a signi \201 - cant contribut ion to calorie intake. An alternative is glu- cose polymer (icodextrin) present in a 7.5% c oncentration. This operates by colloid osmosis as icodextrin has an aver- age molecular wei ght of 20 000Da. Biocompatibility The pH of most commercial \202 uids is <5.5 and contains high lactate an d glucose degradation product concentra- tions. These factors are felt to damage peritoneal lining cells, and newer \202 uids use bicarbonate as the buffer with a more neutral pH a nd fewer glucose degradation products. Patients have much less pain on infusion of these mo re biocompatible products, and these \202 uids will hopefully Fig. 3.3.1 Photograph of a peritoneal dialysis catheter. 71 CHAPTER 3.3 Peritoneal dialysis (PD) \200 \200 \200 \200 Continuous therapy Controllable UF and solute clearance No requirement for expensive, sophi sticated machinery Minimal effects on cardiovascular stability Less potential for further v ascular insult to the damaged kidney. protect the integrity of the peritoneal membrane and pro- long the ef \201 ciency of the p eritoneal membrane to clear solute and water. PD as renal replacement therapy Adequacy of PD and assessment of peritoneal function As men tioned previously there is a wide variation in effec- tive peritoneal surface area, and thi s can be assessed for long-term PD by measuring the peritoneal solute clear- ance. The used dialysate is collected for 24h and a plasma sample taken. The urea and creatinine are meas ured in both the \202 uid and plasma. With the dialysate volume, a 24h clearance can be c alculated, and conventionally this is expressed as weekly clearance by multiplying by 7 and standardized by the body surface area. For the patient \200\231s total clearance, the effe ct of residual renal function must be added to this result. A creatinine clearance of >50l/ 1.73m2 is regarded as satisfactory. Formal testing of the peritoneal membrane can be per- f ormed by the peritoneal equilibration test (PET) which gives a value for the rate of transp ortation of water and low molecular weight solute. Patients can then be allocated a categor y of high to low transporters. What is the place of PD in the critically ill? Formerly PD was a relatively common form of treatment for acute renal failure but, as the technology of haemodi- alysis and then contin uous RRT developed, it has fallen out of favor other than for pediatric practice where vasc ular access and extracorporeal circuit management can be extremely dif \201 cult. In situa tions where the sophisticated resources required to apply modern continuous RRT is not avai lable, PD has a continuing place in situations where the peritoneal cavity is not compromis ed, for example by intra- abdominal surgery. The original method where repeated rigid cathe ter insertion was used probably has no place, but the modern methods of insertion of Tenckh off cathe- ters allow relatively simple catheter placement. Ash has recently argued the cas e for the place of PD in the critically ill and the potential for high frequency cycling al lowing the high solute clearances felt necessary for the critically ill. Complications \200 Management of the CAPD patient with critical illness There are a large number of ESRD patie nts receiving PD as their replacement therapy and, on occasion, they will require critical care. Depending upon the problem, man- agement of their renal failure can usually be contin ued using PD, the one obvious exception being major intra- abdominal surgery. This will nee d to be supervised by staff fully trained in this treatment to avoid the common com- plicat ions and ensure good catheter function. The dialysis regime will need to be adapted by incr easing the solute clearance, as is normally necessary in the critically ill, and to adjust UF as indicated by the patient \200\231s condition. If there is no-one with CAPD experience present in the critical care unit, then the catheter can be locked and the RRT method with which the unit is familiar instituted until the patient can be transferred to a center fam iliar with PD or recovers to be able to supervise their own treatment. Infection: this may be of the peritoneum or the tunnel site. Peritonitis is easily detected by the development of cloudiness of the ef \202 uent dialysate often associated with pain . Samples are sent for microbiology, and antibiotic treatment is given intraperitoneally ac cording to the center \200\231s regime. Occasionally the cause will be due to a gastrointes tinal or gynecological source rather than external contamination of the dialysate \202 ui d. Prevention of infection has improved greatly over the years, with speci \201 c systems introduced to minimize the risk of con- tamination during bag changes. Many patients now ha ve years between episodes of cloudy \202 uid/infection, Leaks: dialysate may leak through the catheter track, into the pleural space, soft tissues or into a hernial sac Catheter in sertion complications: bleeding, organ dam- age, etc. Catheter malposition or malfunction, e.g. \201 brin blockage. Constipation. Membrane failure: for solute transportation, UF or both. Sclerosing peritonitis. Pain. Hernia development, \200 \200 \200 \200 \200 Further reading Ash SR. Peritoneal dialysis in acute renal failure: the under-utilized modality. Contrib Nephrol 2004; 144: 239 \200\22354. Jacobs C, Kjellstrand CM, Koch KM, Winchester JF, eds. Replacement of renal function by dia lysis, 4th edn. Kluwer Academic Publishers, Dordrecht, 1996. Management of acute renal failure by PD Advantages of PD \200 \200 \200 Johnson RJ, Feehally J, eds. Comprehensive clinical nephrology, 2nd edn. Mosby, St Louis, MO, 2003. Natural membrane Peritoneum impermeable to bacteria No necessity for extracorporeal circuit or anticoagulation This page intentionally left blank 73 Chapter 4 Gastrointestinal therapy techniques Chapter contents Insertion of a Sengstaken \200\223Blakemore tube in critical care 74 Upper gastrointestinal endoscopy 76 Nasojejunal feeding in critical care patients 78 74 PJ ALLEN & J BOOTH Insertion of a Sengstaken \200\223Blakemore tube in critical care aspiration pneumonia, enables insertion of the tube down the esophagus rather than trachea, and is more comfort- able for the patient. The Sengstaken \200\223Blakemore tube should be removed from the fridge immediately prior to insertion. Colder, stiffer tubes are thought to aid insertion, although they probably warm up and soften in a relatively short time. The balloons and channels are then checked for leaks by insuf \202 ating with a 50ml bladder syringe. De \202 ate completely and clamp off the two balloons, and lubricate the tube wit h some water-based lubricating jelly to aid insertion. The insertion can be done with the p atient lying on their back or side (typically left side). An assistant with suction is alwa ys required as variceal bleeds may produce large volumes of blood. The Sengstaken \200\223Blakemore tube is very effective at con- trolling torrential bleedin g from oesophago-gastric varices. Its use is associated with serious complications such as oesophageal ulceration, oesophageal perforation and aspi- ration pneumonia in 15 \200\22320 % of cases. Up to 50% of patients will re-bleed once the balloon is de \202 ated. so its p rimary function is to control bleeding initially prior to further de \201 nitive treatment . Indication Consider inserting a Sengstaken \200\223Blakemore tube where bleeding from oesop hago-gastric varices is not controlled endoscopically, where access to endoscopy is not rea dily available, if the patient is unable to tolerate endoscopic pro- cedures or if the pati ent does not consent to an endoscopy. The Sengstaken \200\223Blakemore tube will control bl eeding in up to 90% of patients but has to be viewed as a temporary solution, as re-bleedin g occurs in 50% of patients on de \202 a- tion of the balloon. It is essential to plan th e next therapeu- tic step within 12 \200\22324h. This will usually be a further attempt at endoscopic therapy, but other options such as a tran- sjugular intrahepatic portosystemic s hunt (TIPSS) and even liver transplantation may be considered. Insertion The lubricated Sengstaken \200\223Blakemore tube is inserted via the nose or the mouth. The nasal route allows easier nurs- ing and is said to be more comfortable for the p atient. Oral insertion can be considered if there is a nasal obstruction or the patient doe s not tolerate nasal insertion. Lidocaine spray can be used in those who are not intubated. Once the insertion point is anesthetized, pass the tube through the nostril into the phary nx and gently push down into the esophagus. There may be a slight resistance as the tube pa sses the larynx and, on entering the esophagus, there is then a slight \200\230give \200 \231. Check that the tube has not curled up in the back of the pharynx. Continue passing th e tube down the esophagus to the 55cm mark from the incisors; indicating a position well be low the gastro-oesophageal junction (GOJ). In \202 ate the gastric balloon with water or a ir and check the position with a chest radiograph: using a mixture of water-soluble contras t material and water may help to visualize the balloon. Once the tube is correctly sited, \201 ll with a maximum volume of 300ml of water (or air). Some clinicians favor \201 lli ng the balloon completely with 300ml initially, as a tube positioned at 55cm below the GOJ has little risk of complications. Novel techniques are being developed such as using ultras ound to ensure correct placement. Once the balloon is \201 lled, gently pull the tube bac k until resistance is felt. Apply traction (see below). Equipment The Sengstaken \200\223Blakemore tube (Fig. 4.1.1.) is a triple lumen tube, and d iffers slightly from the Minnesota tube, a variant used in the same way, in that the Minnes ota has a fourth port to enable aspiration of oesophageal contents and so reduce the risk o f aspiration pneumonia. The tubes are usually stored in the fridge of the emergency depart- ment, endoscopy, admissions unit or theaters. Post-insertion 1 Traction on the tube is maintained by applying tape ( \200\230Sleek \200 \231 or red tape is best) to the skin of the nose only. Weighted traction using bags of sal ine causes necrosis at the GOJ and at the angle of the mouth (if using the oral route). The angle of the mouth can be further protected using a tennis ball, with a unilateral longitu dinal slice from one pole to the other, as this will dissipate the pressure over the skin o f the face. 2 Aspirate from all the available portals. 3 Chest radiograph to ensure there i s no oesophageal perforation (subcutaneous emphysema, pneumonitis) and no evidence of aspir ation pneumonia. Esophageal balloon inflation Gastric aspiration Gastric balloon inflation Esophageal balloon Gastric balloon 4 Check the portals, length of the Sengstaken \200\223Blakemore Fig. 4.1.1 A pictorial representation of a Sengstaken \200\223Blakemore tube. tube and angle of mouth at regular intervals. 5 Rarely does the oesophageal balloon need insuf \202 ating. If it is needed to control bl eeding then insuf \202 ate to no more than 40mm Hg and de \202 ate every 4h for 15min to prevent oesophageal necrosis; some advocate de \202 ating for 2min every hour. Preparation It is ideal, though not essential, for the patient to be sedated with an endotr acheal tube in situ as this reduces the risk of 75 CHAPTER 4.1 Insertion of a Sengstaken \200\223Blakemore tube in critical care 6 Regularly suction (15min intervals) or put on continuous low-pressure suction to remove s ecretions via the oesophageal tube as this reduces the aspiration risk. 7 Aspirate the gast ric port every 15min for 4h then hourly to check the bleeding rate. Place on free drainage into a bile bag. from varices and the mortality from sepsis in cirrhotic patients admitted with an upper GI bleed. Follow-up therapy Following insertion of the Sengstaken \200\223Blakemore tube, plans shoul d be made for further de \201 nitive treatment. Once the patient is stable with the Sengst aken \200\223Blakemore tube in place, subsequent endoscopy needs to be per- formed within t he following 24h to allow further attempts at endoscopic therapy. Band ligation of the vari x or inser- tion of the sclerosant ethanolamine are used to achieve haemostasis and to erad icate the varices. A \200\230second look \200\231 endoscopy may be needed after 24 \200 \22348h to assess for re- bleeding. Discussion with the local Liver Unit will cover potenti al candidates for TIPSS or liver transplant. 8 Release traction at 10h and de \202 ate to prevent necrosis. If no bleeding occurs in 1h , de \202 ate completely, and if no further bleeding occurs in the following hour then rem ove the Sengstaken \200\223Blakemore tube. 9 The tube must be removed within 36 \200\22348h . 10 Clear written instructions on the monitoring and care needed must be available for bot h nursing and medical staff. Pharmacological measures In any bleeding patient, good resuscitation, with blood and \202 uids (colloids and crystalloids), and close monitoring of \202 uid balance are most impo rtant to ensure a good outcome for the patient. Diversion of blood \202 ow to the oesopha go-gastric varices is caused by portal hypertension, and diversion away from the varices is achieved pharmacologically with terlipressin (Glypressin) 2mg initially then 1 \200\2232mg 4 \200\2236 hourly up to 72h. The terlipressin constricts the splanchnic vessels and reduc es the venous blood \202 ow through the upper gastroin- testinal (GI) tract. This results in a reduction in the pressure in the collateral circulation and therefore reduces the ris k of bleeding. Glypressin therapy should be initiated in all patients thought to be bleedin g from oesophago-gastric varices unless contraindicated (such as coronary heart disease, ca rdiac failure and polydipsia). In an encephalopathic patient, lactulose may be given down t he gastric port of the tube to encourage bowel action and reduce the risk of encephalopathy . Broad spectrum antibiot- ics have been proven to reduce both the risk of re-bleeding Further reading Bernard B, Grange JD, Khac EN, et al. Antibiotic prophylaxis for the preven tion of bacterial infections in cirrhotic patients with gastrointestinal bleeding: a meta-a nalysis. Hepatology 1999; 32: 142 \200\22353. Dearden JC, Hellawell GO, Pilling J, et al. Does cooling Sengstaken \200\223 Blakemore tube s aid insertion? An evidence based approach. Eur J Gastronenterol Hepatol 2004; 1611: 1229 \200\22332. Douglass A, Bramble MG, Barrison I. National survey of UK emer- gency endoscopy units. BMJ 2005; 330: 1000 \200\2231. Kupfer Y, Cappell MS, Tessler S. Acute gastrointestinal bleeding in the intensive care unit . The intensivist \200\231s perspective. Gastroenterol Clin North Am 2000; 29: 275 \200\223 307. Lin AC-M, Hsu Y-H, Wang T-L, et al. Placement con \201 rmation of Sengstaken \200\223Blake more tube by ultrasound. Emerg Med J 2006; 25: 487. Panes J, Teres J, Bosch J, et al. Ef \201 cacy of balloon tamponade in treatment of bleedi ng gastric and esophageal varices. Results in 151 consecutive episodes. Dig Dis Sci 1988; 3 34: 454 \200\2239. Vlavianos P, Gimson AES, Westaby D, et al. Balloon tamponade in variceal bleeding: use and misuse. BMJ 1989; 298: 1158. 76 PJ ALLEN & J BOOTH Upper gastrointestinal endoscopy Acute GI hemorrhage is the main indication for endos- copy in the critical care setting. En doscopy is the primary diagnostic and therapeutic technique used in patients with GI bleedi ng. Acute upper GI bleeding has an incidence ranging from 50 to 150 per 100 000 of the popu lation each year. The hospital mortality has remained steady at 10% for patients admitted for GI bleeding but is 30% for patients who develop GI bleeding while in hospital for other reasons. Many of these patients are older or have signi \201 cant cardiovascular, respira tory or cerebrovascular co-morbidity. Assessment of severity It is important to stratify patients into those with a high or low r isk of death. The Rockall score has now become the standard scoring score used in most acut e centers (see Chapter 20.4). Resuscitation The initial management is to establish an adequate airway and to ensure adequ ate venous access with a least a 14 or 16 gauge IV cannula. A central venous catheter shoul d be considered in patients with signs of major hemorrhage. Initial \202 uid replacement can be with crystalloid but, if there are signs of shock (pulse >100bpm), then 500ml of col loid should be administered immediately. Blood should be trans- fused when bleeding is extr eme and/or when the Hb is <10g/l. The initial (pre-transfusion) Hb should be interpreted wi th caution as this is a poor indicator of the severity of bleeding. Presentation Patients may present with vomiting fresh blood or \200\230coffee ground \200 \231 altered blood. Patients may also present with melaena (black tarry stools), and 10% o f lower GI bleeds (haemochezia) will have an upper GI cause. The majority of patients requi re admission, although a small proportion of young/ \201 t patients with self-limiting ble eding may not. Re- bleeding is de \201 ned as fresh haematemesis and/or melaena with the d evelopment of shock (pulse >100bpm, systolic pressure <100mm Hg) or a reduction in Hb conce ntration >20g/l over 24h. Initial investigations A full set of baseline blood tests should be taken including electro lytes and clotting (particularly when liver disease is suspected). Four units of blood shou ld be cross-matched, although O negative blood can be given in dire situations. ECG, CXR an d blood gasses are advisable in those with car- diorespiratory disease. Causes A cause for upper GI bleeding is found in 80% of cases (Table 4.2.1) Endoscopy Most patients can be endoscoped on the next available list, usually within 12 \200\22324h. Emergency endoscopy should be considered in: \200 patients with chronic live r disease \200 patients presenting with shock with signi \201 cant concur- Table 4.2.1 Causes of acute upper gastrointestinal hemorrhage Diagnosis Approximate % rent illnesses Peptic ulcer Gastroduodenal erosions Oesophagitis Varices Mallory \200\223Weiss tear Upper gastrointestinal malignancy Vascular malformations 35 \200\22350 8 \200\22315 5 \200\22315 5 \200\22310 15 1 5 patients with clinical evidence of re-bleeding following a primary intervention. In most cases, endoscopy is best performed in an endos- copy unit but severely bleeding pat ients may be best man- aged with an endotracheal tube in place in a critical care setting. Endoscopy must be performed by experienced operators able to achieve haemostasis in patient s with bleeding from ulcers and varices. It is equally important that assistants have been adequately trained and are famil- iar with the endoscopic equipment and their accessories. Endoscopy will usually reveal the source of bleeding, give some indication of prognosis and enable endoscopic therapy. The prognosis is partly dependent on identi \201 cation of sti gmata of recent hemorrhage (SRH) as revealed in the Rockall score. It is therefore importan t to take appropriate steps to identify clearly the source of bleeding. This may involve th e use of washing catheters, change of position of the patient and, in experienced hands, an y clot should be removed (washed/snared) to expose the bleeding point so that endoscopic th erapy can be targeted. Other 5 Hospital management Patients with significant upper GI bleeding should be looked after by s pecialist gastroenterologists (physicians or surgeons) in a safe environment. This may be a n acute medical ward where the medical and nursing staff have experience of the problem or critical care units for severely ill patients. The management of these patients in special- ized units has been shown to reduce the mortality from 11 to 5%. There must be round the c lock expertise includ- ing access to emergency endoscopy, surgery and indeed blood transfus ion. There should be agreed protocols avail- able to all for the management of upper GI hem orrhage. Details of admission and subsequent events must be clearly recorded. Endoscopic therapy Patients without SRH have a low risk of re-bleeding and should not be tr eated endoscopically as their prognosis is good. A variety of techniques have been develope d to treat patients with major SRH. In patients found to have bleeding due to oesophago- ga stric varices, both sclerotherapy with ethanolamine and band ligation can be used. Scleroth erapy involves the Clinical approach The management depends on a number of factors includ- ing the assessment of severity and cause of bleeding, along with the age and presence of co-morbid factors. 77 CHAPTER 4.2 Upper gastrointestinal endoscopy as part of the initial management of patients with signi \201 - cant upper GI bleeding (se e Chapter 20.4). There is little evidence to support the use of other agents, although ther e is some evidence that tranexamic acid may reduce the need for surgical intervention. injection of the sclerosant ethanolamine through a needle injection catheter both para- and intravariceally. More recently, band ligators that attach to the distal end of the endosco pe have been developed to allow suction of the varix and then release of a tight band aroun d the base of the varix. Often patients will be initially treated with sclerosant, but then bands should be applied as quickly as possible as this technique is better at controlling bleeding and, importantly, reducing the risk of re-bleeding. If endoscopy fails to stop the bleeding then a Sengstaken \200\223 Blakemore tube may be used, and occasionally TIPSS or rarely surgery may be indicated. All patients with variceal bleeds should be started on IV antibiotics. Patients with bleeding from ulcers can be treated with injec- tion, applicatio n of heat or with mechanical clips. Local expertise will determine which techniques are use d, but recent studies suggest that dual therapy with two of the above techniques will reduc e the risk of re-bleeding by 30%. Injection therapy involves injecting 1:10 000 adrenaline solution in quadrants around the bleeding point, then direct injection into the bleeding ve ssel. 95% patients will stop bleeding, but re-bleeding will occur in up to 20% of these. Th ermal haemostasis is achieved with heater probes or argon beam plasma coagulators. The heat er probe uses both pressure and heat to achieve haemostasis with success equal to injection therapy. A variety of mechanical clips have been developed to apply to bleeding points, an d are particularly useful for visible larger vessels. These techniques can be used to treat other causes of bleeding such as Mallory \200\223Weiss tear, vascular malforma- tions (arg on beam particularly useful) and the tricky Dieulafoy lesion. Follow-up Patients should resume drinking 4 \200\2236h after endoscopy. Repeat endoscopy is required if there is evidence of fresh bleeding or if there if there is concern that optim al treatment was not possible at the initial endoscopy (poor views, etc.). A surgical opini on is required in bleeding that cannot be stopped by endoscopic intervention and in the fol lowing circumstances: \200 any patient requiring early endoscopy \200 patients >65 who remain unstable after \211 4 units of blood patients <65 who remain unstable after \211 8 units of blood patients with signi \201 cant re-bleeding. Patients who have bled from ulcers should recei ve stand- ard ulcer healing therapy, which often includes Helicobacter eradication. Patient s taking non-steroidal anti-in \202 amma- tory drugs (NSAIDs) or aspirin should stop these drugs. Patients who bled from gastric ulcers should undergo repeat endoscopy 6 weeks after discharge to ensure ulcer healing and to exclude malignancy. Repeat endoscopy is usually n ot necessary in the duodenal ulcer group. Further reading Holman RA, Davis M, Gough KR. Value of centralized approach in the manageme nt of haematemesis and melaena; experience in a district general hospital. Gut 1990; 31: 50 4 \200\2238. Medical therapy A neutral gastric pH is required to improve the stability of clots over ble eding arteries. Whilst there is little evidence to support H2 antagonists in the acute sett ing, there is increasing evidence that using proton pump inhibitors (PPIs) early leads to i mprovements in outcome. In one study from Nepal, high dose oral omeprazole was shown to red uce blood transfusion requirements and the risk of bleeding when compared with placebo. In more recent studies, high dose intravenous PPIs led to reductions in the rate of re-bleedin g, blood transfusion requirement, duration of hospital stay and the need for endoscopic the rapy. There was a non-statistical trend to reduced mortality in the treated group. A high d ose PPI is therefore recommended (80mg bolus followed by an infusion of 8mg hourly for 72h) Khuroo MS, Yattoo GN, Javid G. A comparison of omeprazole and placebo for bleeding peptic u lcer. N Engl J Med 1997; 336: 1054 \200\2238. Lau JYW, Leung WK, Wu JC, et al. Omeprazole before endoscopy in patients with gastrointesti nal bleeding. N Engl J Med 2007; 356: 1631 \200\22340. Lau JYW, Sung JJY, Lee KKC, et al. Effect of intravenous omeprazole on recurrent bleeding a fter endoscopic treatment of bleeding peptic ulcers. N Engl J Med 2000; 343: 310 \200\2236. Rockall TA, Logan RFA, Devlin HB, et al. Incidence of and mortality from acute upper gastro intestinal haemmorrhage in the United Kingdom. BMJ 1995; 311: 222 \200\2236. Stiegmann GV, Goff JS, Michaletz Onody PA, et al. Endoscopic scle- rotherapy as compared wi th endoscopic ligation for bleeding oesophageal varices. N Engl J Med 1992; 326: 1527 \200 \22332. 78 PJ ALLEN & J BOOTH Nasojejunal feeding in critical care patients Who needs NJ feeding? Due to dif \201 culties placing and maintaining an NJ feeding system , the NG route should be used routinely, with NJ reserved for particular cases. The main in dications for a NJ feeding tube are post-gastric/oesophageal surgery and acute severe pancr eatitis, but patients with gastric atony or gastoparesis, who are at risk of aspiration, ma y also bene \201 t. The risk of aspiration due to NG feeding is 6.5% , whilst the risk of aspiration in NJ feeding is 2.4%. Consider percutaneous endoscopic gastrostomy (PEG) or per cutaneous endo- scopic jejunostomy (PEJ) in patients requiring long-term feeding (>4 \200 \2236 weeks). Combining NJ feeding with a gastric aspiration port helps to reduce gastric v olumes and so reduces the risk of aspiration. Critical care patients are often malnourished, due to either poor nutritional status prior to admission, inadequate calorie intake for nutritional needs or a combination of both. Ent eral nutrition (EN) helps the gut function normally and keeps the integrity of the mucosal barrier, and so decreases gut permeability, reducing the risk of bacteraemia and endotoxaem ia. Bacterial and toxin translocation is prevented by the barrier function of the small bow el mucosa, but this is com- promised early in the disease process of critically ill patient s, as demonstrated by increased gut permeability to polyethylene glycol. Studies of trauma, burns and major surgery patients have shown improved outcome with EN compared with total p arenteral nutrition (TPN), and this has been replicated with those with severe acute pancre a- titis. Furthermore, EN caused a reduced incidence of systemic in \202 ammatory response syndrome (SIRS), a reduced APACHE II score, C-reactive protein (CRP) and serum IgM antiend otoxin antibodies, but an increased total antioxidant capacity. Gastroduodenal dysmotility is a common problem in critical care and may result from the underlying illness, but also f rom medication such as sedatives or analgesics. Dysmotility prevents or reduces ef \201 ca cy of nasogastric (NG) feeding, and large gastric residual volumes place a patient at risk of re \202 ux, vomiting and aspiration. Nasojejunal (NJ) feeding can overcome these dif \201 culties, and enable the patient to receive suf \201 cient calorie intake. Methods 1. Bedside NJ insertion A simple NJ tube can be placed at the bedside by laying the patient at 30 \200\22345 . A motility stimulant (e.g. metoclopra- mide or erythromycin) c an be given 30min prior to inser- tion for improved insertion rates. Mark off the NJ tube a t the level of the stomach (40 \200\22345cm) and measure off another 25 \200\22330cm to all ow insertion into the jejunum. Pass the lubricated tube down the nose into the stomach and at the \201 rst marked point blow in air to con \201 rm placement. Roll the patient into the right lateral oblique position at the same angle for the head and continue advancing i nto the duodenum. Blowing in air now should produce \201 ne rather than harsh crackles. P lacement in the left lower lung in patients with pulmonary oedema or pneumonia can mimic th at of air blown in the stomach. Aspirates of \202 uid from the duodenum and beyond should be alkaline. Push to the sec- ond mark and con \201 rm the position using an abdominal ra diograph with or without contrast. Nutritional assessment and treatment General malnutrition (protein-calorie) can be assessed from the history (anorexia, dietary history, calorie intake) and examination (muscle wasti ng, oedema, angular stomatitis). Objective bedside measurements can include weight loss >10 % in the preceding 3 months, blood tests (albumin <35g/l, lymphocytes <1.5x109, transferrin <2g/l), skin fold tests (mid-triceps skin fold thickness <8mm in men and 17mm in women, an d mid-arm muscle circumference <30cm on men and 26cm in women) and a BMI <19kg/m2. Obese pa tients should receive nutritional treatment according to their ideal body weight for their height, with a 30% supplement for increased metabolic requirements in critical care setting s. There are several factors to consider for nutritional treat- ment: 1 Fluid balance 2 Ene rgy from fat and carbohydrates (30 \200\22360 kcal/kg/24h) 3 Nitrogen requirements (0.16 \200\2230.35g/kg/24h) 4 Electrolytes 5 Trace elements and vitamins Typical feeding regimes will need working out with hospital dieticians, but typical polymeric feeds are Jevity (Abb ott) and Osmolite (Abbott), which comprise protein, carbohy- drate, fat, vitamins and miner als. Continuous drip feeding reduces the complications of re \202 ux, aspiration or diar- rhoea. Starting rates should be in the order of 30ml/h and increased as the patient tolerat es. Additional \202 uid needs should be provided with water. Feed containers and giving s ets should be changed every 24h to prevent bacterial con- tamination. 2. Fluoroscopic insertion Move the patient to a suitable area for radiological screening. P ass an NJ tube using a guide wire and \202 uoroscopic screen- ing into the jejunum. Posit ion can be checked at the same time. 3. Endoscopic insertion In the critical care or endoscopy unit pass the gastroscope into th e duodenum. A nasobiliary guide wire (ERCP guide wire) is passed down the biopsy channel an d, once in the duodenum, pushed as far as possible past the second part into the jejunum. R emove the endoscope and maintain the wire in position either using screening or by insertin g it in a stepwise fashion by as much as the endoscope is removed. Once the endoscope is re moved, convert the orojejunal guide wire to an NJ wire by a naso-oral exchange. Pass a plas tic tube over the guide wire in a Seldinger method into the jejunum. Check the position wit h a contrast abdominal radiograph or by screening, and remove the guide wire. Evidence, disadvantages and alternative techniques Success rates for jejunal placement rema ins low at 14%, so techniques to make the insertion more reliable have been developed: weig hted ends, balloons and spiral cork- screws. ECG monitoring with a change in the polarity a s the tube passes the pylorus gives fast placement within 15min (range 7 \200\22375) with 6 5% placed the \201 rst time, and a further 79 CHAPTER 4.3 Nasojejunal feeding in critical care patients \200 \200 