- Email: [email protected]
BEDSIDE APTT AND PT MONITORING
British Journal of Anaesthesia 1993; 71: 164-173
CORRESPONDENCE
R. IMBERTI I. PRESEGLIO G. VERDE
Pavia, Italy 1. Mallett SV, Cox DJA. Thrombelastography. British Journal of Anaesthesia 1992; 69: 307-313. 2. Spiess BD, Tuman KJ, McCarthy RJ, DeLaria GA, Schillo
R, Ivankovich AD. Thromboelastography as an indicator of post-cardiopulmonary bypass coagulopathies. Journal of Clinical Monitoring 1987; 3: 25-30. Mannucci PM, Federici AB, Sirchia G. Hemostasis testing during massive blood replacement. Vox Sanguinis 1982; 42: 113-123.
Sir,—Thank you for the opportunity to reply to this letter. The management of the acutely bleeding patient is undoubtedly facilitated by the use of "bedside" coagulation tests. It is important, however, that the costs of these tests are balanced against the amount of information gained: for instance, the current U.K. cost of Ciba Corning PT is £3.34 per cartridge and the APTT is £4.20. Whether APTT and PT monitoring alone can rationalize the use of blood products is somewhat debatable, as these tests are limited to the start of clot formation and do not help in assessing its dynamic development, stability and strength. Bedside monitoring of APTT (and PT) would, however, seem to be a major advance for the clinician managing anticoagulated patients during operation or in the intensive care unit. Before blood product therapy such as fresh frozen plasma is used to correct a prolonged PT and APTT, it is clear that more work needs to be done to define "normal" changes in patients undergoing extensive surgery with and without major bleeding, as striving to keep these variables within tight limits may be both unnecessary and unrealistic. We agree with the authors that it would be of interest to evaluate further the use of bedside testing of PT and APTT in surgical patients. S. V. MALLETT
D. J. A. Cox Royal Free Hospital London SORE THROAT AFTER SUXAMETHONIUM Sir,—In their paper comparing alfentanil and suxamethonium, used to facilitate intubation for day-case dental surgery [1], Alcock and colleagues express surprise at the greater incidence of postoperative sore throat in those patients receiving suxamethonium [1]. They would have expected this complication to be more common in the alfentanil group, because of the increased manipulation of the tracheal tube sometimes required in these less-well relaxed patients. (Placement of the pharyngeal pack would, similarly, tend to be more traumatic.) The authors are unable to explain this preponderance of sore throat in the suxamethonium group. I suggest that this discomfort was merely the interpretation by the patient of myalgia affecting the muscles of the pharynx—that is, a local manifestation of the generalized muscle stiffness and pain associated with suxamethonium. It would be instructive to examine the data produced by the study for any possible correlation between sore throat and muscle pain. S. J. DE C. DEACOCK
Charing Cross Hospital London 1. Alcock R, Peachey T, Lynch M, McEwan T. Comparison of alfentanil with suxamethonium in facilitating nasotracheal intubation in day-case anaesthesia. British Journal of Anaesthesia 1993; 70: 34-37. RESPIRATORY DEPRESSION AFTER EXTRADURAL FENTANYL Sir,—The letter by Wang [1] adds one more to at least three existing case reports on ventilatory depression after single extradural injections of fentanyl [2-4]. The attribution of the effect to perispinous vascular communications between extradural and cerebral blood vessels is unconvincing. It is hard to reconcile
Downloaded from http://bja.oxfordjournals.org/ at University of Exeter on July 14, 2015
BEDSIDE APTT AND PT MONITORING Sir,—Recently an extensive and interesting review in the BJA [1] emphasized the importance of thrombelastography (TEG) for monitoring coagulation in the perioperative period. Whereas TEG investigates haemostasis as a whole dynamic process, activated thromboplastin time (APTT) and prothrombin time (PT) represent isolated end-points in haemostasis and give no information on interaction between platelets and the coagulation cascade [1]. However, we wish to present a clinical report showing that, at least in certain circumstances, bedside "real-time" monitoring of APTT and PT can improve the management of patients by anaesthetists, in the operating theatre. A 67-yr-old woman, recovering from inferior left limb thrombosis, manifested epigastric pain after eating. Radiological examinations (stomach x-ray and abdomen CT scan) and gastric biopsies demonstrated diffuse infiltrative adenocarcinoma of the stomach extending to the pancreas. A few days later, new thrombosis developed, occluding the deep veins of the inferior right limb. The patient was treated with infusion of heparin (about 25000 iu day"1), maintaining APTT between 1.5 and 2.5 times normal. The patient was scheduled to undergo surgery and, 2 days before the date appointed for operation, the heparin infusion was reduced to 15000 iu day"'. Complete thrombosis developed of the right subclavian and internal jugular vein. Heparin infusion was increased and surgery delayed until resolution of the thrombosis. The heparin infusion was reduced (500 iu h"1) only 3 h before operation. At the beginning of surgery, APTT was 18 s (normal values 18-31 s), the International Normalized Ratio (INR) was 1.2 and other variables of haemostasis (platelets, fibrinogen, antithrombin III, fibrin degradation products) evaluated by the central laboratory were within the normal range. During the operation (gastrectomy and resection of body and tail of the pancreas), serial measurements of APTT and PT were performed on fresh whole blood at the patient's bedside, using a 512 coagulation monitor (Ciba Corning, U.S.A.)—a small, rechargeable, portable instrument. One drop of fresh whole blood is deposited on the surface of a test cartridge containing dry reagents which activate the coagulation process. Results are obtained within 2-3 min and data expressed in seconds, the ratio between the patient's and the normal value and INR. During the operation, the patient received crystalloids 2000 ml and plasma expanders 1000 ml, packed red cells 5 units, 500 ml of blood cells as autotransfusion and fresh frozen plasma 3 units. APTT was 18-140 s, INR in the range 1.25-1.78. Ionized calcium was always within the normal range. Monitoring of APTT and PT allowed rapid assessment of heparin infusion and of dilutional hypocoagulability, and the subsequent treatment of these conditions. During the operation there was no clinical evidence of haemorrhage. Twelve hours after the end of the operation, heparin infusion was increased to 900 iu h"1 (APTT 1.5 times normal). The postoperative blood loss was considered normal by the surgeons. Bedside APTT and PT monitoring is reliable and performed easily and quickly. This monitoring aids anaesthetists to manage patients affected by deep venous thrombosis and thrombophylic patients undergoing anticoagulant therapy and who require surgery. APTT was found to correlate significantly with all TEG variables [2] and PT was found to correlate significantly with the number of units of blood transfused [3]. It would be of major interest to investigate if, during haemorrhagic surgical procedures requiring large transfusion, bedside APTT and PT monitoring can help to rationalize the use of blood components.
CORRESPONDENCE
R. IMBERTI I. PRESEGLIO G. VERDE
Pavia, Italy 1. Mallett SV, Cox DJA. Thrombelastography. British Journal of Anaesthesia 1992; 69: 307-313. 2. Spiess BD, Tuman KJ, McCarthy RJ, DeLaria GA, Schillo
R, Ivankovich AD. Thromboelastography as an indicator of post-cardiopulmonary bypass coagulopathies. Journal of Clinical Monitoring 1987; 3: 25-30. Mannucci PM, Federici AB, Sirchia G. Hemostasis testing during massive blood replacement. Vox Sanguinis 1982; 42: 113-123.
Sir,—Thank you for the opportunity to reply to this letter. The management of the acutely bleeding patient is undoubtedly facilitated by the use of "bedside" coagulation tests. It is important, however, that the costs of these tests are balanced against the amount of information gained: for instance, the current U.K. cost of Ciba Corning PT is £3.34 per cartridge and the APTT is £4.20. Whether APTT and PT monitoring alone can rationalize the use of blood products is somewhat debatable, as these tests are limited to the start of clot formation and do not help in assessing its dynamic development, stability and strength. Bedside monitoring of APTT (and PT) would, however, seem to be a major advance for the clinician managing anticoagulated patients during operation or in the intensive care unit. Before blood product therapy such as fresh frozen plasma is used to correct a prolonged PT and APTT, it is clear that more work needs to be done to define "normal" changes in patients undergoing extensive surgery with and without major bleeding, as striving to keep these variables within tight limits may be both unnecessary and unrealistic. We agree with the authors that it would be of interest to evaluate further the use of bedside testing of PT and APTT in surgical patients. S. V. MALLETT
D. J. A. Cox Royal Free Hospital London SORE THROAT AFTER SUXAMETHONIUM Sir,—In their paper comparing alfentanil and suxamethonium, used to facilitate intubation for day-case dental surgery [1], Alcock and colleagues express surprise at the greater incidence of postoperative sore throat in those patients receiving suxamethonium [1]. They would have expected this complication to be more common in the alfentanil group, because of the increased manipulation of the tracheal tube sometimes required in these less-well relaxed patients. (Placement of the pharyngeal pack would, similarly, tend to be more traumatic.) The authors are unable to explain this preponderance of sore throat in the suxamethonium group. I suggest that this discomfort was merely the interpretation by the patient of myalgia affecting the muscles of the pharynx—that is, a local manifestation of the generalized muscle stiffness and pain associated with suxamethonium. It would be instructive to examine the data produced by the study for any possible correlation between sore throat and muscle pain. S. J. DE C. DEACOCK
Charing Cross Hospital London 1. Alcock R, Peachey T, Lynch M, McEwan T. Comparison of alfentanil with suxamethonium in facilitating nasotracheal intubation in day-case anaesthesia. British Journal of Anaesthesia 1993; 70: 34-37. RESPIRATORY DEPRESSION AFTER EXTRADURAL FENTANYL Sir,—The letter by Wang [1] adds one more to at least three existing case reports on ventilatory depression after single extradural injections of fentanyl [2-4]. The attribution of the effect to perispinous vascular communications between extradural and cerebral blood vessels is unconvincing. It is hard to reconcile
Downloaded from http://bja.oxfordjournals.org/ at University of Exeter on July 14, 2015
BEDSIDE APTT AND PT MONITORING Sir,—Recently an extensive and interesting review in the BJA [1] emphasized the importance of thrombelastography (TEG) for monitoring coagulation in the perioperative period. Whereas TEG investigates haemostasis as a whole dynamic process, activated thromboplastin time (APTT) and prothrombin time (PT) represent isolated end-points in haemostasis and give no information on interaction between platelets and the coagulation cascade [1]. However, we wish to present a clinical report showing that, at least in certain circumstances, bedside "real-time" monitoring of APTT and PT can improve the management of patients by anaesthetists, in the operating theatre. A 67-yr-old woman, recovering from inferior left limb thrombosis, manifested epigastric pain after eating. Radiological examinations (stomach x-ray and abdomen CT scan) and gastric biopsies demonstrated diffuse infiltrative adenocarcinoma of the stomach extending to the pancreas. A few days later, new thrombosis developed, occluding the deep veins of the inferior right limb. The patient was treated with infusion of heparin (about 25000 iu day"1), maintaining APTT between 1.5 and 2.5 times normal. The patient was scheduled to undergo surgery and, 2 days before the date appointed for operation, the heparin infusion was reduced to 15000 iu day"'. Complete thrombosis developed of the right subclavian and internal jugular vein. Heparin infusion was increased and surgery delayed until resolution of the thrombosis. The heparin infusion was reduced (500 iu h"1) only 3 h before operation. At the beginning of surgery, APTT was 18 s (normal values 18-31 s), the International Normalized Ratio (INR) was 1.2 and other variables of haemostasis (platelets, fibrinogen, antithrombin III, fibrin degradation products) evaluated by the central laboratory were within the normal range. During the operation (gastrectomy and resection of body and tail of the pancreas), serial measurements of APTT and PT were performed on fresh whole blood at the patient's bedside, using a 512 coagulation monitor (Ciba Corning, U.S.A.)—a small, rechargeable, portable instrument. One drop of fresh whole blood is deposited on the surface of a test cartridge containing dry reagents which activate the coagulation process. Results are obtained within 2-3 min and data expressed in seconds, the ratio between the patient's and the normal value and INR. During the operation, the patient received crystalloids 2000 ml and plasma expanders 1000 ml, packed red cells 5 units, 500 ml of blood cells as autotransfusion and fresh frozen plasma 3 units. APTT was 18-140 s, INR in the range 1.25-1.78. Ionized calcium was always within the normal range. Monitoring of APTT and PT allowed rapid assessment of heparin infusion and of dilutional hypocoagulability, and the subsequent treatment of these conditions. During the operation there was no clinical evidence of haemorrhage. Twelve hours after the end of the operation, heparin infusion was increased to 900 iu h"1 (APTT 1.5 times normal). The postoperative blood loss was considered normal by the surgeons. Bedside APTT and PT monitoring is reliable and performed easily and quickly. This monitoring aids anaesthetists to manage patients affected by deep venous thrombosis and thrombophylic patients undergoing anticoagulant therapy and who require surgery. APTT was found to correlate significantly with all TEG variables [2] and PT was found to correlate significantly with the number of units of blood transfused [3]. It would be of major interest to investigate if, during haemorrhagic surgical procedures requiring large transfusion, bedside APTT and PT monitoring can help to rationalize the use of blood components.