Critical Care Obstetrics part 18 ppsx

Vascular Access 159 ing external pressure on the IJV in the supraclavicular area for 10 seconds. During the application of pressure, the central venous pressure and waveform were observed. In all cases of catheter misplacement into the IJV, the central venous pressure increased 3 – 5 mmHg. If the misplaced catheter was in another vessel, the central venous pressure did not change with this maneuver. An attempt to compare IJV, SCV and femoral vein sites for subsequent thrombosis, stenosis and infection suggested that the SCV site is less often associated with infection, mechanical complications and thrombosis compared to the other sites [60] . Femoral v ein From lateral to medial, the femoral nerve, artery and vein traverse the femoral triangle by descending beneath the inguinal ligament [46] . The femoral vein can be located 1 – 2 cm medial to the palpated femoral artery pulse. If the femoral artery cannot be palpated, the location of the femoral vein can be estimated by imagining a line from the anterior superior iliac crest to the pubic tubercle and then dividing the line into equal thirds. The femoral artery lies at the junction of the middle and most medial segment and the femoral vein can be estimated as 1 – 2 cm medial to this point (Figure 10.7 ). The skin is punctured 2 – 3 cm caudal to the inguinal ligament to ensure the vein is cannulated in the area of the thigh. A catheter at least 15 cm in length can then be inserted into the femoral vein by directing the tip toward the vein at a 45 ° angle to the skin. Once in the vein, the angle of the catheter may be placed more parallel to the skin surface in order to align with the lumen of the vessel. The advantage of using the femoral vein is its large size and the absence of risk of pneumothorax; however, cannulation is generally not recommended for cardiopulmonary resuscitation or in the presence of bleeding disorders [8] . Complications of femoral vein cannulation include arterial puncture, hematoma, bleeding, local infl ammation, malposition of catheters tip, and thrombosis [61] . Cephalic v ein In its course away from the axillary vein, the cephalic vein travels below the clavipectoral fascia in the deltopectoral groove and descends down the lateral aspect of the arm [46] . The cephalic vein is most often used for central venous access via surgical cutdown. Specifi c a rterial a ccess s ites Radial a rtery The brachial artery divides into the radial and ulnar arteries in the forearm. The radial artery is a favored site for arterial cannulation due to its superfi cial location medial to the styloid process. The ulnar artery parallels the radial artery. Together, the radial and ulnar arteries form anastomosing palmar arches supplying blood to the hands [46] . Prior to cannulation of the radial artery, adequacy of collateral circulation must be established. The Allen clavicle touching the bone itself as needed, pointing toward the suprasternal notch and parallel to the patient ’ s back. Upon enter- ing the vein, the bevel is turned to the 3 o ’ clock position to facilitate passing the catheter. Immediate risks of SCV cannulation include pneumothorax, hemothorax, and catheter misplacement. The most common of these complications is pneumothorax with an incidence of 1 – 6%. Pneumothorax is primarily associated with direct subclavian or jugular vein catheterization. Collin and Clarke [56] reviewed the occurrence of delayed or late pneumothorax (48 – 72 h) following central venous catheterization and recommended that postinser- tion chest radiographs be expiratory and upright. Expiration results in a decreased volume of air in the lung but not in the pleural space thus magnifying the radiographic appearance of the pneumothorax [57] . Finally, repeat or delayed chest radiographs are indicated following catheterizations requiring multiple attempts, persistent (pleuritic or back) pain and respiratory symptoms. The standard treatment for pneumothorax has tradi- tionally consisted of placement of a thoracostomy tube. However in an investigation by Laronga [58] , pneumothorax was managed by observation alone and/or the insertion of a pigtail catheter (8.5 French) with a Heimlich valve in the outpatient setting. Also, in spontaneous breathing patients who have developed a small pneumothorax, the use of 100% oxygen therapy for 60 minutes may denitrogenate and attenuate the pneumothorax, thus avert- ing chest tube insertion. Hemothorax is an infrequent complication of direct SCV catheterization. Because intrathoracic vascular structures are inacces- sible for direct compression, subclavian and, to a lesser degree, IJV direct venous catheterization are contraindicated in patients with a coagulopathy. A common location for misplacement of the catheter is in the ipsilateral IJV. Misplacement is most often detected by radiographic studies. Another technique has been described using the IJV occlusion test [59] . The occlusion test is performed by apply- Figure 10.6 Landmarks for subclavian vein cannulation. Using the clavicle, the subclavian vein is divided into thirds. The junction of the middle and medial third identifi es the location for needle insertion. Chapter 10 160 ARTERY VEIN B C A Figure 10.7 Estimating femoral vein location. When the femoral arterial pulsations cannot be appreciated, the location of the femoral vein can be estimated. (a) Draw a line from the anterior superior iliac crest to the public tubercle and (b) divide into equal thirds. The junction of the medial and middle segment approximates the femoral artery and the vein will lie 2 – 3 cm more medial (c). indicates an incomplete or occluded ulnar arch. Failure to regain normal color promptly is presumptive evidence of inadequate collateral fl ow, and the radial artery should not be cannulated. In performing this test, care is taken not to hyperextend the wrist, which could falsely compromise ulnar fl ow. Once adequate collateral circulation has been determined, preparation for cannulation of the radial artery can be under- taken. The wrist is dorsifl exed slightly to optimize exposure of the artery. This is best accomplished by use of an arm board and placement of a small gauze roll beneath the dorsal surface of the wrist, with tape placed across the patient ’ s palm and upper forearm. When taping the upper forearm, care is taken not to constrict blood fl ow. Alternatively, an assistant may hold the patient ’ s arm in place, but access to the puncture site is often obstructed in so doing. Once positioned, the area is prepped and anesthetized as described previously. We prefer using a 20 – 22 - gauge Angiocath. The needle is advanced at a 30 ° angle to the artery until a fl ash of blood appears in the hub. If using the direct puncture technique, the angle of the needle is then slightly lowered and the catheter advanced while holding the needle stable. This can often be facilitated by rotating the catheter itself backward and forward, in a drilling motion. If the catheter fails to advance easily, the operator should avoid trying to force the catheter because of the risk of traumatic pseudoaneurysm. Often, both walls of the vessel will have been punctured and the catheter will lie posterior to the vessel. If the catheter has been advanced beyond the tip of the metal needle do not advance the needle farther because of the risk of damage to the catheter. Instead, completely remove the needle and then slowly withdraw the catheter until pulsatile fl ow is established. At that moment, one can gently reattempt to advance the catheter or pass a 25 - gauge vascular wire through the catheter, followed by advancement over the wire. If neither of these maneuvers is met with success, the catheter should be removed and discarded. The procedure is then repeated with a new needle and catheter. If the Seldinger technique (or a modifi cation thereof) is used, the needle is advanced until a fl ash of blood is observed in the hub, after which the guidewire is advanced through the needle until it is 2 – 3 cm into the artery. The catheter can then be advanced over both guidewire and needle, or the needle can be removed and the catheter advanced over just the guidewire. Once the catheter has been advanced, the guidewire and/or needle are removed, pulsatile fl ow is established, and the line is secured and connected. Rarely, cutdown and direct visualization will be required for radial artery catheterization. If a cutdown becomes medically necessary, a 2 - cm transverse incision is made 2 cm proximal to the wrist fold, and the vessel is located by blunt dissection with small hemostats. The hemostats should separate the tissue in a plane parallel to the vessel to minimize vessel trauma. Skin hooks are helpful to hold the incision open. The dissection also is guided by intermittent palpation to maintain orientation to the vessel. Once exposed, a 1.0 – 1.5 cm length of vessel should be cleaned and mobilized, and 2 - 0 or 3 - 0 silk sutures are passed beneath the test can be used in an attempt to document the adequacy of collateral fl ow. Even so, progressive delayed ischemia of the hand may occur, requiring amputation [62] . Blanching of the skin may occur with fl ushing of the catheter and indicate interference with skin circulation. In cases of radial line - induced ischemia where perfusion to the hand has been compromised, we have successfully used a stellate ganglion block to promote vasodilation and return perfusion to near necrotic fi ngers. Allen t est The Allen test is performed in the following manner. 1 The radial and ulnar arteries are occluded simultaneously. 2 Continuing this occlusion, the patient elevates the hand above his or her head. 3 He or she repeatedly makes a fi st until the hand blanches. 4 The pressure on the ulnar artery is then released. The palm should regain its normal color within 6 seconds. Delay of color from 7 to 15 seconds indicates that ulnar artery fi lling is slow. Persistent blanching for up to 15 seconds or more Vascular Access 161 chial plexus may also occur during insertion attempts because of the vessel ’ s relationship with the three cords of the brachial plexus. At this point, these cords form a neurovascular bundle within the axillary sheath. As for brachial cannulation, distal circulation should be checked regularly following axillary arterial line insertion. Dorsalis p edis a rtery The dorsalis pedis artery is located on the dorsal aspect of the foot and is usually easily palpated, but may be absent in 12% of the population. Collateral blood supply is usually good, and ischemia is uncommon following cannulation of this vessel. Collateral circulation, supplied by the lateral plantar artery, can be assessed by compression of the dorsalis pedis artery, followed by pressure on the nail bed of the great toe until it blanches. On release of pressure on the nail bed, color should return within 2 – 3 seconds. To facilitate cannulation of the dorsalis pedis artery, hold the patient ’ s foot in a neutral position, and introduce a 20 - or 22 - gauge needle into the artery at a shallow angle to the skin. Femoral a rtery The femoral artery as an extension of the external iliac artery lies just below the inguinal ligament midway along a line drawn from the superior iliac spine and symphysis pubis just lateral to the vein and medial to the nerve. The usual catheters employed range from 20 to 16 gauge, are 16 cm in length, and are attached to a 10 - mL syringe. The needle is inserted about 2 cm below the inguinal ligament and at a 45 ° angle to the skin. The puncture of the vessel can often be felt by the operator and is heralded by the ability to rapidly aspirate bright red blood. Also, a gloved fi nger placed over the hub of the needle can usually feel the arterial pulsations. Once the vessel is punctured, the needle is lowered to an angle between 15 – 30 ° and a J - tipped guidewire is inserted into the vessel. The needle is removed, and direct pressure is applied to the insertion site to prevent bleeding or hematoma formation. The catheter is placed over the guidewire, but it is not advanced until the distal (external) tip of the guidewire itself has been secured. Care is also taken to ensure that the wire is straight, as any kinks will make passage of the catheter diffi cult. A scalpel nick of the skin may be required for ease of passage of the catheter through the skin. Once the catheter is in place, the wire is removed and the catheter connected and secured. A complication peculiar to femoral vessel cannulation is puncture of the back wall of the vessel above the inguinal ligament. The resulting hemorrhage may dissect into the retroperitoneal space masking a hemorrhage of up to several liters. Because of the large size of the femoral artery, vein and the catheters used in these vessels, the chances of an AV fi stula is higher than with smaller vessels, especially if both vessels have been penetrated during a single insertion. Similarly, the larger puncture site makes bleeding at the time of line removal an issue. Under these circum- stances, pressure should be applied to the femoral site for 10 – 20 minutes following catheter removal. vessel with a right - angle clamp. To assist catheter insertion, one approach is to place one suture proximal and one distal to the site of vessel puncture. The distal suture can be used to elevate the vessel for direct visual puncture. If vessel puncture is not initially successful, traction on the proximal suture will stop the bleeding, providing visualization of the puncture site and thus allowing the catheter to be inserted without the necessity of another puncture. Once catheterized, both sutures are removed (not tied) and the skin is closed. Pressure should be maintained on the cutdown site for 5 or 10 minutes to prevent potential hematoma formation. Brachial a rtery The brachial artery is the continuation of the axillary artery. Collateral circulation is supplied by the ulnar collateral artery. This artery is best isolated just above the elbow crease medial to the biceps tendon. A 20 - gauge, 2 - inch catheter is inserted at a 30 ° angle to the skin until blood appears in the hub. The vessel is cannulated by either the direct, modifi ed, or classic Seldinger technique. Use of an arm board prevents fl exion at the elbow and kinking of the catheter. Use of the brachial artery entails greater risks than use of the radial artery. These risks include, but are not limited to, the following: (i) adequacy of collateral circulation is much more diffi cult to ensure; (ii) embolization could occlude either of the major arterial supplies to the hand; and (iii) bleeding in the area of the median nerve may result in neuropathy and Volkmann ’ s contracture. If bleeding does occur, a fasciotomy may be surgically necessary [63] . Cannulation of the brachial artery should not be attempted in patients with disorders of hemostasis. Axillary a rtery The axillary artery is a continuation of the subclavian artery. It enters the axilla from under the teres major and lies in the proximal groove between the biceps and triceps muscles medially in the arm. This artery is almost as large as the femoral artery and has signifi cant collateral fl ow. As such, axillary artery thrombosis does not lead to distal ischemia. Since the right axillary artery arises from the right brachiocephalic trunk, which is itself in direct communication with the common carotid artery, air, clot, or particulate matter may embolize the brain during fl ushing. Thus, it may be safer to use the left axillary artery. For cannulation, the patient can be positioned either with the palm of the hand beneath the occipital portion of the head or with the arm extended and externally rotated. After the vessel is located by palpation, an 18 – 20 - gauge catheter, measuring at least 5 cm, is inserted into the artery until pulsatile blood is observed in the hub. The angle of insertion should initially be at about a 30 ° angle to the skin, and once blood return is noted, the angle is lowered for direct advancement or guidewire insertion. Because of the close proximity of the axillary artery and the brachial plexus, hematoma formation in this area could result in nerve compression. Additionally, direct injury to the cords of the bra- Chapter 10 162 line in detecting CRBSI, while quantitative blood cultures are more diffi cult and expensive to perform and could be reserved as a confi rmatory test when needed. The endoluminal brush seems best reserved for instances where blood cannot be withdrawn from the catheter [66,67] . Catheter removal is also generally recommended in catheterized patients whose presumed catheter - unrelated infections fail to rapidly improve with appropriate treatment. Others have investigated the effi cacy of thrombolytic therapy in treating catheter colonization or infection [68] . The Centers for Disease Contol (CDC) have issued guidelines intended to minimize and monitor CRI [16] . These guidelines include, but are not limited to, the following: • selection of insertion site (subclavian versus femoral) • strict adherence to aseptic technique at the time of both insertion and dressing change • changing gauze dressings every 2 days • changing transparent dressings every 7 days • not routinely replacing catheters or guidewires with the intent of preventing infection • creating “ catheter teams ” . It is recommended that each patient care area that utilizes central catheters maintain a surveillance system whereby infection is documented by specifi cally using number of CRBSIs per 1000 catheter - days. Documenting infection in this manner can help facilitate interpretation of outcomes between patient care units. In previous studies, antimicrobial/antiseptic impregnated catheters were associated with a reduction in CRBSI [69 – 72] . However, in its latest recommendation the CDC suggests limiting the use of antimicrobial/antiseptic impregnated catheters to areas of the hospital with unacceptably high CRBSIs rates (in spite of implanting appropriate measures) or to patients expected to have the catheter in place for longer than 5 days. The National Nosocomial Infection Surveillance System (NNISS) compiles hospital data to issue benchmarks for CRBSI rates and these data can be used for comparisons. Though a specifi c obstetric category is not tracked by the NNISS, data could be extrapolated from Surgical and Medical Teaching categories with pooled mean infections/1000 catheter - days of 5.3. Creating a surveillance system, standardizing catheter - related education and creating teams vested in catheter care cannot be emphasized enough. Frankel et al. [73] clearly demonstrated the importance of such measures in decreasing the CRBSI in their unit from 11 (well above national benchmarks) to 1.7 per 1000 catheter days by combining corporate performance improvement methodologies, changes in operating procedures, feedback and reviews. Conclusion Short - and long - term central venous access is a vital tool in women ’ s healthcare. The proper and safe use of central catheters requires knowledge of indication, meticulous sterile technique, Catheter - r elated i nfection Catheter - related infections (CRIs) include exit - site and tunnel infections, catheter - associated bacteremia or sepsis, suppurative thrombophlebitis, endocarditis, and clavicular osteomyelitis. The exact incidence for catheter - related bloodstream infections (CRBSIs) is diffi cult to determine due to a number of factors. However, it is estimated that 80 000 cases occur annually in intensive care units alone; and, of these, there is a potential mortality rate of 35% [16] . Factors contributing to CRI include type of catheter and catheter material, number of insertion attempts, duration, location, type of dressing, experience of personnel, indication for catheter insertion and virulence of the infecting organism [16,64,65] . Upper extremity locations for catheter insertions are less often associated with infection compared with those inserted in the lower extremities. Coagulase - negative Staphylococcus , followed by Enterococcus and Staphlococcus aureus are the organisms most commonly associated with catheter - related bloodstream infection. Unfortunately, antibiotic resistance is also more frequently encountered with these organisms. Catheter - related bloodstream infection is suspected clinically when signs of infection at the exit site are seen (e.g. erythema, tenderness, purulent drainage) or systemic signs of infection (e.g. fever, rigors, fl uid sequestration, rising peripheral WBC count) are noted, particularly in patients lacking another likely source of infection. Historically, when signs of catheter - related bloodstream infection became manifest, the catheter was removed for culture of the catheter tip. Unfortunately, many catheter tip cultures returned as negative and only a small percentage of infections could actually be linked to the catheter. Catheter lumen colonization is a prerequisite to CRBSI. This knowledge has prompted the development of in situ techniques to determine catheter colonization and possibly avoid catheter removal. Such techniques include the following. 1 S u p e r fi cial, semiquantitative culture from the skin at the exit site and the catheter hub. A dry cotton swab is used to sample a 3 - cm area around the exit site, and another dry cotton swab is introduced into the catheter hub. 2 Paired quantitative blood cultures from the peripheral blood and catheter. Peripheral blood (10 mL) is obtained and distributed into aerobic and anerobic culture media followed by blood from the catheter (10 mL from each lumen) which is likewise distributed. 3 Differential time to positivity of simultaneous samples from peripheral blood and the catheter hub. Again, 10 mL is obtained, simultaneously from the peripheral blood and catheter lumen. 4 Endoluminal brushing of the catheter. This technique was described as useful when blood could not be obtained from the catheter. The superfi cial semiquantitative and differential time to positivity are sensitive and specifi c enough to be considered as fi rst Vascular Access 163 precautions during insertion . Infect Control Hosp Epidemiol 1994 ; 15 : 231 . 20 Larson EL. Guidelines for use of topical antimicrobial agents. APIC Guidelines for Infection Control Practice . Am J Infect Control 1988 ; 16 : 253 – 266 . 21 Wyatt WJ , Beckett TA , Bonet V , Davis SM . Comparative effi cacy of surgical scrub solutions on control of skin microfl ora . Infect Surg 1990 ; 9 : 17 – 21 . 22 Sheikh W. Comparative antibacterial effi cacy of Hibiclens and Betadine in the presence of pus derived from human wounds . Curr Ther Res 1986 ; 40 : 1096 . 23 Seldinger SI . Catheter replacement of the needle in percutaneous arteriography . Acta Radiol Diagn 1953 ; 39 : 368 – 376 . 24 Beards SC , Doedens L , Jackson A , Lipman J . A comparison of arterial lines and insertion techniques in critically ill patients . Anaesthesia 1994 ; 49 : 968 – 973 . 25 Denys BG , Uretsky BF , Reddy PS et al. An ultrasound method for safe and rapid central venous access . N Engl J Med 1991 ; 324 : 566 . 26 Sherer DM , Abulafi a O , DuBesher B et al. Ultrasonographically guided subclavian vein catheterization in critical care obstetrics and gynecologic oncology . Am J Obstet Gynecol 1993 ; 169 : 1246 . 27 Schummer W , Schummer C , Rose N et al. Mechanical complications and malpositions of central venous cannulations by experienced operators. A prospective study of 1794 catheterizations in critically ill patients . Intensive Care Med 2007 ; 33 : 1055 . 28 Goodwin ML , Carlson I . The peripherally inserted central catheter . J Intravenous Nurs 1993 ; 16 : 92 . 29 Nohr C . Vascular access , in Wilmore DW , Cheung LY , Harken AH , Holcroft JW , Meakins JL (eds): Scientifi c American Surgery, Surgical Technique Supplement 3 . New York, NY , Scientifi c American , 1994 , pp 1 – 28 . 30 Agee KR , Balk RA . Central venous catheterization in the critically ill patient . Crit Care Clin 1992 ; 8 : 677 . 31 LaFortune S. The use of confi rming x - rays to verify tip position for peripherally inserted catheters . J Intravenous Nurs 1993 ; 16 : 246 . 32 Lucey B , Verghese JC , Haslam P , Lee MJ . Routine chest radiographs after central line insertion: mandatory postprocedural evaluation or unnecessary waste of resources . Cardiovasc Intervent Radiol 1999 ; 22 : 381 – 384 . 33 Baranowsky L. Central venous access devices: current technologies, uses, and management strategies . J Intravenous Nurs 1993 ; 16 : 167 . 34 Kaye A. Invasive monitoring techniques: arteruak cannulation, bedside pulmonary artery catheterization and arterial puncture . Heart Lung 1983 ; 12 : 395 – 427 . 35 Lowell JA , Bothe Jr. A. Venous access: preoperative, operative, and postoperative dilemmas . Surg Clin North Am 1991 ; 71 : 1231 . 36 Fry B. Intermittent heparin fl ushing protocols. A standardization issue . J Intravenous Nurs 1992 ; 15 : 160 . 37 Lawson M . Partial occlusion of indwelling central venous catheters . J Intravenous Nurs 1991 ; 14 : 157 . 38 Wachs T. Urokinase administration in pediatric patients with occluded central venous catheters . J Intravenous Nurs 1990 ; 13 : 100 . 39 Holcombe BJ , Forloines - Lynn S , Garmhausen LW. Restoring patency of long - term central venous access devices . J Intravenous Nurs 7 A.D.; 15 : 36 . 40 Haire WD , Lieberman RP , Lund GB et al. Obstructed central venous catheters. Restoring function with a 12 - hour infusion of low - dose urokinase . Cancer 1990 ; 66 : 2279 . insertion techniques, competence in recognizing and treating complications, maintenance, and surveillance. 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Internal jugular vein occlusion test for rapid diagnosis of misplaced subclavian vein catheter into the internal jugular vein . Anesthesiology 2001 ; 95 : 1377 – 1379 . 60 Hamilton H , Foxcroft D . Central venous access sites for the prevention of venous thrombosis, stenosis and infection in patients requiring long - term intravenous therapy . Cochrane Database Syst Rev 2007 ; 3 . 61 Durbee O , Viviand X , Potie F et al. A prospective evaluation of the use of femoral venous catheters in critically ill adults . Crit Care Med 1997 ; 25 : 1943 . 62 Mangar D , Laborde RS , Vu DN . Delayed ischaemia of the hand neces- sitating amputation after radial artery cannulation . Can J Anaesth 1993 ; 40 : 247 – 250 . 63 Hudson - Civetta J , Caruthers - Banner TE. Intra - vascular catheters: current guidelines for care and maintenance . Heart Lung 1983 ; 12 : 466 – 476 . 64 Egebo K , Toft P , Jakobsen CJ . 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Sacks Department of Research, Southern California Permanente Medical Group, Pasadena, CA, USA Introduction Transfusion of blood components is a potentially life - saving procedure. Although meticulous care is taken in the selection of blood donors, processing, storage, and transfusion of blood products, serious transfusion - related complications may ensue. It is incumbent on the physician to be sure that a blood product is indicated, and that standard transfusion practices and precautions are observed [1] . This chapter is intended as an aid to understanding the preparation of, indications for, and potential complications of blood components for obstetric critical care. Blood d onation, c ollection, and s torage Blood d onation The prerequisites for blood donors are stringent, and require that the potential donor be in good health and not have been exposed to drugs which may have a deleterious effect on blood components (e.g. aspirin on platelet function). The donor must also be free of bloodborne bacterial, viral, and protozoal agents as well as not having had sexual contact with those who may be infected with these agents. A partial list of the American Association of Blood Banks ’ (AABB) requirements for donors is found in Table 11.1 . Of note is the response to the 2003 FDA requirement for screening blood for West Nile virus. The bones of contention are that bloodborne West Nile viral infections are infrequent (0.44 per 10 000 donations in 2004 [2] ), are of low infectious potential, and require costly testing. A strategy of testing “ minipooled ” blood samples from several donors during the half of the year when the incidence of infection is low, with individual testing reserved for those contributing to a positive minipool, has been proposed. The proposal includes individual testing during an outbreak [3] . Because the recipient is the same person as the donor, the requirements for an autologous donor are less stringent than those for allogeneic donors. Requirements include a hemoglobin of only 11 g/dL, deferral only when there is a possibility of bacteremia in the donor, and that the collection be performed no fewer than 72 hours before the anticipated transfusion [1] . Apheresis is a procedure wherein whole blood is withdrawn from a donor, a liquid (e.g. plasma) or solid (e.g. platelets) portion is retained, and the remainder of the blood reinfused. The time interval between donations is shorter for apheresis donors than for donors of whole blood. For example, donors of platelets may undergo apheresis up to twice a week, but no more than 24 times a year [1] . However, the other requirements for allogeneic donors also apply to apheresis donors (Table 11.1 ). Blood c ollection and i mmediate s torage A unit of blood should be collected with a minimum of trauma and over a short time period (4 – 10 minutes) to decrease the likelihood of activation of coagulation factors. Each collection bag usually contains an average of 450 ± 45 mL of whole blood plus 63 mL of anticoagulant/preservative. The purpose of the anticoagulant/preservative is to prevent clotting and to maintain cell viability and function. Two commonly used storage solutions are CPD (citrate - phosphate - dextrose) and CP2D. The citrate chelates calcium, and prevents activation of the calcium - depen- dent steps of the coagulation process. Dextrose serves as a sub- strate for red cell glycolysis, while phosphate buffers lactic acid produced by metabolism. Storage of collected blood at 1 – 6 ° C slows glycolysis. If, however, platelets are to be separated from the whole blood the latter must be fi rst cooled to no lower than 20 ° C and the platelets separated within 4 hours of phlebotomy. The United States Food and Drug Administration (FDA) approves storage of blood products containing red cells (RBCs) at 1 – 6 ° CC in CPD and CP2D for 21 days. The addition of adenine to the storage solution (e.g. in CPDA - 1) to support RBC synthesis of ATP allows the blood to be stored for 35 days. Within 72 hours of collection and following removal of plasma (see below) 100 mL of an additive solution containing such substances as saline, Chapter 11 166 adenine, mannitol, and dextrose to support red cell survival may be added from a satellite bag to the remaining red cells, thus prolonging the shelf life of the unit to 42 days [4] . Separation of w hole b lood into c omponents The term “ blood component therapy ” refers to the use of specifi c components of whole blood for a specifi c patient ’ s needs. By Age Minimum 17 years Volume of blood collected Maximum 10.5 mL/kg of donor weight Donation interval 8 weeks Blood pressure ≤ 180 mmHg systolic ≤ 100 mmHg diastolic Pulse 50 – 100 BPM non - athletic; < 50 BPM in a healthy athlete Temperature ≤ 37.5 ° C Hemoglobin/hematocrit ≥ 12.5 g/dL/ ≥ 38% Drugs taken Aspirin: defer for 36 hours beyond last ingestion Isotretinoin: defer for one month after last dose Bovine insulin from the UK: defer indefi nitely Medical history Family history of Creutzfeldt – Jakob disease: indefi nite deferral Pregnancy: Defer for 6 weeks after pregnancy termination Receipt of blood components Defer for 12 months Infectious disease Indefi nite deferral History of viral hepatitis ≥ age 11 HBsAg [+] Repeated reactive test for anti - HBc antibody Present or past clinical or laboratory test for HIV, HCV, HTLV, or syphilis History of babesiosis or Chagas ’ disease Stigmata of parenteral drug use 12 - month deferral from time of: Sexual contact with an HIV - infected individual or one at high risk for HIV infection Sexual contact with an individual who has any form of clinically active viral hepatitis Sexual contact with an individual who is HBsAg [+] Sexual contact with an HCV [+] individual who has had clinical hepatitis within the past 12 months History of, or completion of therapy for syphilis or gonorrhea Malaria Diagnosis of, or symptoms of malaria after having lived in an endemic area: defer for 3 years after becoming asymptomatic Having lived in an endemic area for ≥ 5 years: defer for 3 years after departing the area Having traveled to an endemic area: defer for 12 months after departing the area West Nile virus Defer per FDA recommendations Table 11.1 Selected requirements for allogeneic blood donors, per AABB standards [1] . using blood components, 1 donor unit can benefi t several patients, as well as allowing conservation of unused components for future use. In addition, components may be used to manu- facture such derivatives as individual coagulation factors and immune globulin. To maintain sterility, and thus shelf life, a unit of blood to be divided into components is collected into a primary bag to which up to three satellite bags are attached. Because red Blood Component Replacement 167 Red b lood c ells l eukocyte r educed A unit of RBCs contains 1 – 3 × 1 0 9 leukocytes. A unit of RBCs leukocyte reduced must contain no more than 5 × 1 0 6 leukocytes per unit and must contain 85% of the RBCs in the original unit [1] . Leukocytes may be removed from whole blood following addition of the anticoagulant/preservative by in - line fi ltration. By centrifugation of the fi ltered product both leukocyte - reduced RBCs and plasma may be retained. Alternatively, RBCs may be fi ltered after separation from plasma in the blood collection center or in the laboratory. Prestorage and laboratory leukocyte reduction is preferable to in - line leukocyte reduction at the time of transfusion. During storage leukocytes fragment, degranulate, or die, potentially releasing substances that result in febrile non - hemolytic transfusion reactions [8] . In addition, removal of leukocytes within 24 hours of phlebotomy may reduce the risk of bacterial contamination of the RBC product [9] . Antibodies to leukocyte antigens are responsible for febrile non - hemolytic transfusion reactions. Thus transfusion of RBCs leukocyte reduced is indicated for patients who have had recurrent febrile non - hemolytic transfusion reactions. Others who may benefi t from receiving RBCs leukocyte reduced are those who are likely to have been previously exposed to leukocyte antigens. Included among the latter are women who have had several pregnancies and those who have received or who anticipate receiving several transfusions [10] . In addition, this product has been found to be as safe as cytomegalovirus - seronegative blood in preventing the transmission of this bloodborne viral pathogen [11] . Red b lood c ells w ashed Washing red cells in 1 – 2 L of normal saline removes 99% of plasma proteins as well as electrolytes, some granulocytes, platelets, and cellular debris. Approximately 20% of the red cell volume is lost during washing. Washed cells are usually resuspended in normal saline to a hematocrit of 70 – 80%, in aliquots of about 180 mL. Cells may be obtained from banked blood at any time during the shelf life of the unit. Because washing takes place in an open system, and because washed cells are separated from their preservative solution, they must be used within 24 hours of washing to prevent bacterial contamination and maintain cell viability. Red cells washed are indicated for IgA - defi cient recipients at risk for anaphylaxis due to exposure to IgA antibodies in donor plasma. They are not a substitute for red cells leukocyte depleted [5] . Red b lood c ells f rozen; r ed b lood c ells d eglycerolized Long - term storage of frozen red cells may be indicated for those individuals who have rare blood types and for some autologous donors. In the process of cooling extracellular water freezes before intracellular water. The resultant osmotic egress of intracellular water results in red cell dehydration. To prevent this, glycerol, a cryoprotective agent to which the red cell membranes are permeable, is added to create an intracellular osmotic force preventing cellular dehydration. In addition, a high concentration (e.g. 40%) of glycerol prevents formation of ice crystals cells, plasma, and platelets have different specifi c gravities, they are separated and initially stored in these satellite bags by differential centrifugation [4] . While a detailed description of all available blood products is beyond the scope of this chapter, a brief description of those products used for obstetric critical care follows. For greater detail, interested readers are referred to appropriate texts [4,5] . Whole b lood and c omponents: d escription and i ndications Whole b lood A unit of whole blood has a volume of approximately 500 mL and an additional 70 mL of anticoagulant/preservative. The hematocrit of the unit is from 36 to 44%. At the time of collection a unit of whole blood contains red cells, granulocytes, platelets, and plasma. After 24 hours of storage few platelets and granulocytes remain. Levels of labile coagulation factors V and VIII diminish progressively with storage, while stable clotting factors II, VII, IX, X, and fi brinogen are maintained. In addition, 2,3 - diphosphogly- ceric acid (2,3 - DPG), an intracellular molecule that promotes dissociation between hemoglobin and oxygen, decreases with storage to a concentration of zero after 2 weeks [6] . Functionally, a decrease in 2,3 - DPG in stored red cells results in less oxygen release to peripheral tissues than is released by fresh cells. However, 2,3 - DPG is completely restored in blood 24 hours after transfusion [7] . Because whole blood provides both oxygen carriage and volume expansion, current indications for whole blood are limited to use for patients at risk for hemorrhagic shock, e.g. those who have lost 25% of their blood volume and who have persistent blood loss [5] . While an advantage of whole blood is the limited number of donors to whom the recipient is exposed, whole blood does not provide platelets and labile clotting factors. A unit of whole blood raises the hematocrit by 3 – 4%. Because of concerns for fl uid overload, whole blood should not be used for normovolemic patients. Red b lood c ells ( RBC s ) RBCs are prepared by centrifuging whole blood followed by separation of the RBCs from plasma. A unit of RBCs collected in CPD or CPDA - 1 has a hematocrit of 65 – 80%. Because of the greater volume of anticoagulant/preservative used, a unit stored in additive solution has a hematocrit of 55 – 65%. The indication for RBC transfusion is a need for oxygen carriage. Because a unit of RBCs contains the same number of red cells as does a unit of whole blood, it, too, will raise the hematocrit by about 3 – 4%. Recently the collection of RBCs by apheresis has gained in popularity, partially in response to a shrinking donor base. Apheresis allows for the collection of 2 units of red cells at the same time. This has the benefi t of exposing the recipient to fewer donors and to a lower transfusion risk while providing potential cost savings. However, the interval between red cell donations by apheresis lengthens to 16 weeks [1] . Chapter 11 168 for febrile non - hemolytic transfusion reactions. Controversy exists regarding whether of not their use is protective against platelet refractoriness [13] . Platelets leukocyte reduced are, however, useful in reducing transmission of CMV [14] . Fresh f rozen p lasma and t hawed p lasma A unit of fresh frozen plasma (FFP) is prepared by fi rst separating plasma from red cells in whole blood within 8 hours of phlebotomy. It may be banked for 1 year if then frozen to − 18 ° C, and for 7 years frozen at − 65 ° C [1] . Plasma may also be obtained by apheresis. As with apheresed red cells and platelets, apheresis offers the opportunity of collecting 2 units of plasma at the same collection from the same donor. A unit of FFP contains all clotting factors, including labile factors V and VIII. Likely the most common indication for FFP in obstetrics is in the face of sudden massive decrease of clotting factors, such as is seen in disseminated intravascular coagulation (DIC) and the dilutional coagulopathy accompanying volume replacement for hemorrhage. Once stabilized, the patient ’ s need for further FFP transfusion should be based on laboratory testing, as clinical bleeding due to clotting factor defi ciency is rarely seen if the International Normalized Ratio (INR) is below 1.6 for activated partial throm- boplastin time and prothrombin time. An INR of 1.6 or greater indicates factor concentrations of 30% or lower [15] . FFP is also indicated for patients who have congenital factor defi ciencies for which specifi c factor concentrates are not available, such as factors II, V, X, and XI [4,5] . While the volume of plasma transfused is a function of clinical response, 3 – 6 units will raise the concentration of coagulation factors in a factor - depleted patient by 20% [5] . While compatibility testing is not necessary, transfused plasma should be ABO compatible with recipient ’ s blood [1] . Once thawed to 30 – 37 ° C it should be either immediately transfused or stored for no more than 24 hours at 1 – 6 ° C. From the time of thawing to 24 hours thereafter this product is renamed “ FFP thawed ” . “ Thawed plasma ” is thawed FFP stored at 1 – 6 ° C days beyond the initial 24 hours of thawing and may be transfused for up to 5 days after thawing. While this product is defi - cient in factor VIII, it retains the minimum factor V activity (35%) required for coagulation [5] . Cryoprecipitated a ntihemophilic f actor ( CRYO ) A unit of CRYO is prepared by thawing a unit of FFP to 1 – 6 ° C. The supernatant plasma is then removed. The remaining insolu- ble portion (the precipitate) along with about 15 mL of plasma is refrozen to − 18 ° C and may be stored for up to 1 year. A unit of CRYO contains concentrated factor VIII:C (procoagulant), factor VIII:vWF (von Willebrand ’ s factor), factor XIII, and fi brinogen. Its major indication in obstetrics is for the replacement of concentrated fi brinogen in the presence of DIC. In addition, CRYO to which thrombin has been added (to convert the fi brinogen in CRYO to fi brin) has been found to form an effective plug in vitro for punctured amniotic membranes [16] . which may destroy cell membranes [4] . A unit of glycerolized red cells may be stored at − 65 ° C for up to 10 years. Ordinarily red cells are frozen within 6 days of collection. However, cells stored at 1 – 6 ° C in CPD or CPDA - 1 may have their ATP and 2,3 - DPG restored by adding an FDA - approved solution of pyruvate, inosine, phosphate, and adenine within 3 days of expiration. These rejuvenated cells may then be glycerolized and frozen [1,4] . To prepare frozen cells for use they are washed in dextrose and saline solutions of progressively decreasing osmolarity, to maxi- mize removal of glycerol and to minimize cell damage and loss. At least 80% of cells must be recovered following deglycerolyza- tion. Red cells deglycerolized in an open system must be transfused within 24 hours. Those deglycerolized in a closed system may be stored at 1 – 6 ° C for up to 14 days [1,4,5] . Platelets Random donor platelets are separated from whole blood that has not been cooled below 20 ° C within 4 hours of phlebotomy. Following centrifugation the platelets are resuspended in 50 – 70 mL of plasma, an amount necessary to maintain stable clotting factors, and a pH of at least 6.2. To maintain viability and function they are stored at temperatures of 20 – 24 ° C with constant gentle agitation for up to 5 days. Platelets may also be obtained by apheresis. A unit of random donor platelets contains 5.5 × 1 0 10 platelets. A unit obtained by apheresis contains 3 × 1 0 10 platelets, or the equivalent of 5 – 6 random donor units. Platelet transfusions are indicated for bleeding associated with thrombocytopenia (platelet count less than 50 000/ µ L). They may be indicated in the face of thrombocytopenia associated with platelet destruc- tion (e.g. autoimmune thrombocytopenia, disseminated intravascular coagulation) accompanied by bleeding. One unit of random donor platelets raises the platelet count by 5000, while an apheresed unit raises the count by 30 – 60 000. Because they express ABO antigens on their surface and because donor plasma may contain anti - A or - B antibodies, platelets ideally should be ABO - compatible with recipients ’ blood. Because a unit of platelets may contain red blood cell fragments, Rh - negative recipients should receive platelets from Rh - negative donors. As a rule, apheresed platelets are preferable to random - donor platelets. Transfusing the same volume of platelets from a single donor as would be obtained from fi ve or six donors limits the recipients ’ potential exposure to bloodborne pathogens and to alloimmunization. A specifi c indication for apheresed platelets is evidence of platelet refractoriness. This entity is defi ned by a failure to raise the recipient ’ s platelet count by a calculated minimum number [12] , and is usually due to recipient antibodies to Class I HLA antigens on donor platelets. These antigens are integral proteins within the platelet membranes. Apheresed HLA - matched platelets are indicated for such recipients [4,5] . Both random donor and apheresed platelets may be collected using leukocyte reduction fi lters. Platelets leukocyte reduced are indicated (as are red cells leukocyte reduced) for patients at risk . pneu- mothoraces complicating central venous catheter insertion . Am J Surg 2000 ; 180 : 523 . 165 Critical Care Obstetrics, 5th edition. Edited by M. Belfort, G. Saade, M. Foley, J. Phelan and. prevention of central venous catheterization of arterial colonization and infection . Crit Care Med 1996 ; 24 : 181 8 . 72 Rafkin HS , Hoyt JW , Crippen DW . Prevention of certifi ed venous catheter. internal jugular vein: a prospective comparison with the landmark technique in critical care patients . Crit Care Med 2006 ; 10 : R162 . 50 DeMatteis J. Brachial plexus injury caused by internal

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