George Silvay

Ketamine: an update on the first twenty-five years of clinical experience

RésuméPendant presque 25 ans ďexpérience clinique, les bénéfices et les limitations de ľanesthésie à la kétamine ont été généralement bien définis. Les revues extensives de White et al.2 ainsi que celles de Reeves et al.43 ont énormément aidé à comprendre ľanesthésie dissociative. Néanmoins, des études récentes continuent à nous éclairer sur les différents aspects de la pharmacologie de la kétamine et suggèrent de nouvelles utilisations cliniques de cette drogue. Ľidentification du récepteur du N-M ethyl-Aspartate amène une preuve que ľanesthésie et ľanalgésie à la kétamine ont chacune un mécanisme ďaction différent. La liaison stéréospécifique de la (+) kétamine aux récepteurs opiacés in vitro, ľémergence plus rapide de ľanesthésie, et une incidence plus basse de séquelles lors de ľémergence, rend la (+) kétamine une drogue promettante pour des recherches futures. Les applications cliniques de la kétamine qui ressortent récemment, et qui probablement augmenteront dans le futur sont reliées é ľutilisation orale, rectale et intra-nasale de la kétamine pour des fins ďanalgésie, de sédation ou induction anesthésique. La kétamine est actuellement considérée comme une option raisonnable pour ľinduction anesthésique chez les nouveau-nés prématurés en hypotension. Ľexpérience initiale avec la kétamine en injection épidurale et intrathécale ne fut pas prometteuse et les données sont encore préliminaires dans ce domaine. Ľutilisation de la kétamine dans les catastrophes et les manoeuvres militaires va probablement être plus fréquente. La disponibilité clinique du midazolam va complementer ľanesthésie à la kétamine de plusieurs façons. Cette benzodiazépine est rapidement métabolisée. Elle réduit la stimulation cardiovasculaire de la kétamine ainsi que les phénomènes ďémergence sans avoir des métabolites actifs. Elle est disponible sous une forme aqueuse et n’est pas irritante lors de ľinjection intra-veineuse comme le diazépam. La combinaison de la kétamine et du midazolam sera bien acceptée par les patients contrairement à ce qui arrive quand on utilise la kétamine seule. Finalement, il est nécessaire de mentionner la possibilité ďabus de la kétamine.126 Alors que la kétamine n’est pas une substance contrôlée (aux États-Unis) la prudence suggère aux médecins de prendre des précautions appropriées contre son utilisation non-autorisée.

Epidemiology of deep sternal wound infection in cardiac surgery.

OBJECTIVES The aim of this study was to investigate the incidence and predictors of deep sternal wound infection (DSWI) in a contemporary cohort of patients undergoing cardiac surgery. The early and late outcomes of patients with this complication also were analyzed. DESIGN A retrospective study of consecutive patients undergoing cardiac surgery using a computerized database based on the New York State Department of Health registry. Data collection was performed prospectively. SETTING A university hospital (single institution). PARTICIPANTS Five thousand seven hundred ninety-eight patients who underwent cardiac surgery between January 1998 and December 2005 including isolated coronary artery bypass graft (CABG) (n = 2,749, 47%), single- or multiple-valve surgery (n = 1,280, 22%), combined valve and CABG procedures (n = 934, 16%), and surgery involving the ascending aorta or the aortic arch (n = 835, 15%). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The overall incidence of DSWI was 1.8% (n = 106). The highest rate of DSWI occurred after combined valve/CABG surgery (2.4%, n = 22) and aortic procedures (2.4%, n = 19). Multivariate analysis revealed 11 predictors of DSWI: obesity (odds ratio [OR] = 2.2), previous myocardial infarction (OR = 2.1), diabetes (OR = 1.7), chronic obstructive pulmonary disease (OR = 2.3), preoperative length of stay >3 days (OR = 1.9), aortic calcification (OR = 2.7), aortic surgery (OR = 2.4), combined valve/CABG procedures (OR = 1.9), cardiopulmonary bypass time (OR = 1.8), re-exploration for bleeding (OR = 6.3), and respiratory failure (OR = 3.2). The mortality rate was 14.2% (n = 15) versus 3.6% (n = 205) in the control group (p < 0.001). One- and 5-year survival after DSWI were significantly decreased (72.4% +/- 4.4% and 55.8% +/- 5.6% v 93.8% +/- 0.3% and 82.0% +/- 0.6%, p < 0.001). CONCLUSION DSWI remains a rare but devastating complication and is associated with significant comorbidity, increased hospital mortality, and reduced long-term survival.

Excellent Early and Late Outcomes of Aortic Valve Replacement in People Aged 80 and Older

OBJECTIVES: To investigate early and late outcome of aortic valve replacement (AVR) in a large cohort of patients aged 80 and older.

Use of a Left Heart Assist Device after Intracardiac Surgery: Technique and Clinical Experience

A left heart assist device (LHAD) has been employed in 14 patients. All had advanced heart disease and were in low cardiac output after repair, such that they could not be separated from cardiopulmonary bypass despite prolonged support and adjuvant therapy, including drugs, pacing, and use of intraaortic balloon counterpulsation whenever possible. Apart from special cannulas, the equipment necessary for the LHAD is widely available. An asset of the system (left atrial-ascending aorta bypass of the left ventricle) is that it may be terminated without reentering the thorax to remove the cannulas. This is accomplished with precisely fitting obturators that obliterate the cannula lumens and allow the tubes to be permanently implanted. This concept is believed important since critically ill patients requiring support are precisely those in whom added risk would be imposed by a second operation. Of the 14 patients who have had intraoperative and postoperative support (up to 6.8 days), 9 were weaned from the device and 6 were dismissed from the hospital. Four patients remain alive and are improved, the longest at 22 months since operation. The favorable performance of the LHAD suggests that it may prove useful either when intraaortic balloon counterpulsation cannot be successfully deployed or when it has failed to achieve hemodynamic stability.

Autologous platelet-rich plasmapheresis: risk versus benefit in repeat cardiac operations.

Preoperative platelet-rich plasmapheresis has been suggested as a means of reducing homologous blood transfusions in cardiac surgical patients. The current study evaluated this technique in patients undergoing repeat cardiac operations. Fifty-two patients undergoing repeat myocardial revascularization and/or valve replacement were evaluated in a prospective randomized controlled study design. Autologous platelet-rich plasma (PRP) was harvested after the induction of anesthesia in the experimental group. After reversal of heparin, each patient received his or her autologous plasma. Patients in the control group did not have plasmapheresis and received standard transfusion therapy if coagulation variables were abnormal and a coagulopathy was clinically evident. Routine coagulation tests, thromboelastography (TEG), perioperative bleeding, and transfusion requirements were compared in the two groups. Forty-four patients completed the study. A significantly larger volume of packed red blood cells (PRBCs) was transfused in the PRP group than in the control group (P = 0.03). Platelet and fresh frozen plasma (FFP) transfusions did not differ between the two groups. Mediastinal tube drainage did not differ between the two groups. During PRP infusion, 60% of the patients required treatment for moderate hypotension (mean arterial pressure [MAP] < 60 mm Hg). Only 16% of control patients required treatment for hypotension during the comparable time period (P < 0.05). No patient who completed the study returned to the operating room for postoperative bleeding. These data suggest that PRP did not reduce postbypass bleeding or transfusion requirements in repeat cardiac surgical patients. Moreover, the incidence of hypotension during PRP reinfusion introduces a potential risk to the procedure in the absence of any obvious benefit. (Anesth Analg 1995;81:229-35)

Characterization and Management of Cardiac Tumors

Cardiac tumors are infrequent clinical entities with an autopsy frequency ranging from 0.001% to 0.030%. The occurrence of metastatic cardiac tumors has been reported a 100-fold more commonly than primary lesions. Three quarters of primary cardiac tumors are benign; approximately half of these are cardiac myxomas, and the rest are lipomas, papillary fibroelastomas, and rhabdomyomas. Among malignant primary cardiac tumors, the most reported are those histopathologically considered as undifferentiated, followed by angiosarcomas and leiomyosarcomas. Traditionally, cardiac tumors have been identified as curious autopsy findings resulting in a literature paucity of large clinical series, therefore, providing knowledge mostly based on case report collection. However, recent technological advances in noninvasive imaging modalities such as echocardiography and cardiac magnetic resonance imaging (MRI) have resulted in a rapid acquisition of real-time heart images with high spatial and temporal resolution and an excellent tissue characterization of the tumor. This consequent earlier, more frequent, and more complete assessment of cardiac tumors before significant symptoms develop has challenged cardiologists, cardiac anesthesiologists, and surgeons to create a tailored referral pattern and approach.

Predictors and Early and Late Outcomes of Dialysis-Dependent Patients in Contemporary Cardiac Surgery

OBJECTIVES The aim of the study was to investigate the incidence and predictors of renal failure requiring dialysis (RF-D) in a contemporary cohort of patients undergoing cardiac surgery. The authors also analyzed early and late outcome of patients with this complication. DESIGN A retrospective study of consecutive patients undergoing cardiac surgery using a computerized database based on the New York State Department of Health registry. Data collection was performed prospectively. SETTING A university hospital (single institution). PARTICIPANTS Six thousand four hundred forty-nine patients who underwent cardiac surgery between January 1998 and December 2006 including isolated coronary artery bypass graft (CABG) surgery (n = 2,819, 44%), single- or multiple-valve surgery (n = 1,378, 21%), combined valve and CABG procedures (n = 1,032, 16%), and surgery involving the ascending aorta or the aortic arch (n = 1,220, 19%). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The incidence of RF-D was 2.2% (n = 139). The incidence per type of procedure was as follows: CABG surgery (0.8%), valve/CABG surgery (2.7%), valve surgery (2.9%), and aortic surgery (4%) (p = 0.001). Multivariate analysis revealed preoperative renal dysfunction (odds ratio [OR] = 5.5), hemodynamic instability (OR = 5.2), diabetes (OR = 2.6), aortic surgery (OR = 2.2), congestive heart failure (CHF) (OR = 2.1), peripheral vascular disease (PVD) (OR = 1.9), and reoperation (OR = 1.8) as independent predictors of RF-D. The hospital mortality after RF-D was 36.7% (n = 51) compared with 2.9% (n = 180) in the control group (p < 0.001). Long-term survival after RF-D was significantly decreased (1-year and 5-year survival 48.5% +/- 6.1% and 28.7% +/- 7.2% v 94.5% +/- 0.3% and 83.5% +/- 0.6% in the control group, p < 0.001). Hypertension, CHF, and PVD were independent predictors of late mortality. CONCLUSION The authors observed an increase in the overall incidence of RF-D compared with previous studies, probably related to an increased prevalence of patients undergoing more complex procedures with a worsening risk profile. Postoperative RF-D was not only associated with increased hospital mortality and morbidity, but also with a significant reduction of long-term survival in discharged patients. Seven independent predictors of RF-D were identified. Future research efforts should focus on a more precise identification of patients at risk and the development of new treatment modalities, which would potentially prevent the occurrence of this complication.

Haemodynamic response to induction of anaesthesia with ketamine/midazolam

The haemodynamic responses following induction of anaesthesia with ketamine and midazolam have not been determined previously. Twenty adult patients for elective myocardial revascularization were randomized to two regimens for induction of anaesthesia. Patients in Group I received ketamine, 2 mg·kg−1, and midazolam, 0.2 mg·kg−1 and those in Group II received ketamine, 2 mg·kg−1, and midazolam, 0.4 mg·kg−1. Measurements were recorded at baseline, 1 min postinduction, and at one, three, five and ten minutes after tracheal intubation. Tachycardia and hypertension (>20% increases from awake baseline values) were treated with esmolol, 250 μg·kg−1. There were 11 patients in Group I and nine patients in Group II. There were no significant intergroup differences in demographic or haemodynamic variables. Both groups had decreases (P<0.05), in stroke volume, pulmonary capillary wedge pressure, and right ventricular end-diastolic volume at multiple study intervals following anaesthetic induction. None of these changes required clinical intervention. Five patients (all in Group Il) had hypertensive responses to tracheal intubation. Preoperative hypertension (mean arterial pressure ≥100 mmHg) was a predictor (P<0.05) of a hypertensive response to intubation, independent of the midazolam dose. Intravenous ketamine and midazolam was associated with a high incidence (25%) of haemodynamic responses to tracheal intubation. The higher dose of midazolam did not provide any haemodynamic advantage.RésuméLa réponse hémodynamique après induction de l’anesthésie avec kétamine et midazolam n’a pas été déterminée à date. Vingt patients adultes, pour une chirurgie de revascularisation myocardique, furent randomisés en deux groupes. Le groupe I a reçu de la kétamine 2 mg·kg−1, et du midazolam 0,2 mg·kg−1 alors que le groupe II a reçu de la kétamine 2 mg·kg−1 et du midazolam 0,4 mg·kg−1. Les mesures furent enregistrées avant l’induction, une minute post-inductiion, et à trois, cinq et dix minutes après l’intubation trachéale. La tachycardie et l’hypertension (>20% des valeurs de base après induction) furent traitées avec de l’esmolol, 250 μg·kg−1. Il y avait Il patients dans le groupe I et neuf patients dans le groupe II. Il n’y avait aucune différence significative entre les groupes dans les données démographiques et les variables hémodynamiques. Les deux groupes avaient une diminution significative (P<0,05) dans le volume d’éjection, la pression capillaire pulmonaire bloquée, le volume en fin de diastole du ventricule droit aux différents intervalles de l’étude après induction de l’anesthésie. Aucun de ces changements n’a requis une intervention clinique. Cinq patients (tous du groupe II) ont présenté une hypertension lors de l’intubation. L’hypertension préopératoire (pression artérielle moyenne ≥ 100 mmHg) pouvant prédire (P<0,05) la réponse hypertensive lors de l’intubation et indépendamment de la dose de midazolam. L’administration intraveineuse de kétamine et de midazolam fut associée à une inducence élevée (25%) de réponse hémodynamique lors de l’intubation. La dose élevée de midazolam n’a pas fourni d’avantage hémodynamique.

Cardiopulmonary bypass for adult patients: a survey of equipment and techniques

OBJECTIVES The techniques and equipment used for cardiopulmonary bypass for adult cardiac surgery vary among institutions and may change over time. This study sought to document the changing patterns of practice. DESIGN Voluntary survey of meeting participants. SETTING 13th Annual San Diego Cardiothoracic Surgery Symposium (February 1993). PARTICIPANTS There were 331 responses from perfusionists (79.5%), cardiac surgeons (11.2%), and anesthesiologists (6.3%). The majority of these participants were from institutions where more than 1,000 cardiac operations were performed annually. MEASUREMENTS AND MAIN RESULTS It was found that 91.5% of the respondents used membrane oxygenators currently, compared with 5% in 1982 (as reported in a previous survey). Over 80% of the institutions surveyed used some type of perioperative cell-salvaging technique. Arterial line filters were used by 92% of the respondents compared with 64% in 1982. Also, 80% of the respondents were aware of the availability of leukocyte-depleting filters. CONCLUSIONS The probable reasons for the increased utilization of membrane oxygenators and arterial line filters include less damage to the formed elements of blood, fewer gaseous microemboli, and better control of carbon dioxide elimination and oxygenation. The authors anticipate that future surveys will document increased use of leukocyte-depleting filters because of the literature implicating neutrophils as mediators of tissue destruction in various disease processes, including myocardial reperfusion injury.

Continuous ketamine infusion for one- lung anaesthesia

The mechanism which normally affects distribution of blood flow through unventilated areas of the lung is hypoxic pulmonary vasoconstriction; this acts to divert the blood to well ventilated alveoli, resulting in a better ratio of ventilation to perfusion. Several reports have focused attention on the reduction or abolition of this reflex in the unventilated lung by most of the volatile anaesthetic agents used in clinical practice. This response was not abolished by the intravenous anaesthetic agents.One hundred and ten patients undergoing elective pulmonary resection were studied to evaluate the effect of a continuous infusion of ketamine during one-lung anaesthesia, by observing the changes in Pa02as a reflection of shunt. Ketamine was chosen as the intravenous agent for its positive inotropic and chronotropic action. Additionally, by providing both analgesia and hypnosis, we were able to admininster inspired oxygen concentrations of 50-100 per cent without concern that the patient might have recall for events during operation We have demonstrated that in all cases a Pa02 in excess of 9.31 kPa (70 torr) was achieved with ketamine and Fi021 .0as well as an increase in shunt fraction from 25.9 per cent (Fi020.5) to 36.0 per cent (Fi02 1.0).We feel that ketamine provides a satisfactory alternative to the volatile agents for one-lung anaesthesia in patients where relative hypoxaemia might be unacceptable during operation.RéSUMéLa vasoconstriction pulmonaire réflexe à l’hypoxie constitue le mécanisme normal qui vient modifier la distribution du volume sanguin dans les régions non ventilées du poumon. Ceci permet de déevier le flot sanguin vers les alvéoles bien ventilees et d’améliorer le rapport ventilation-perfusion.Plusieurs travaux ont faut etat de l’abolition de la diminution de ce reflexe, dans les regions du poumon non ventilées, par la plupart des agents volatils d’usage courant, alors que les anesthésiques intraveineux ne l’abolissent pas.Nous avons étudié 110 opérés subissant une pneumonectomie élective, dans le but d’évaluer I’influence d’une perfusion continue de kétamine au cours d’anesthésies à un poumon. Les modifications de la Pa02 étaient utilisées comme reflets du shunt. Le choix de la kétamine comme agent d’anesthésie a été basé sur ses propriétés inotropes et chronotropes. En plus de fournir a la fois l’analgésie et l’amnésie, cet agent nous permettait d’administrer de Toxygène à des concentrations de 50 à 100 pour cent sans crainte de mémorisation de la chirurgie par le patient. Dans tous les cas, nous avons observe une Pa02 superieure à 9.31 kPa (70 torr) avec la perfusion de ketamine et une Fi02 de 1.0, de même qu’une élévation du shunt qui passait de 25.9 àa 36 pour cent en faisant passer la Fi02 de 0.5 à 1.0.En conclusion, nous considérons la kétamine comme une bonne alternative aux anesthésiques volatils au cours d’anesthésie à un seul poumon chez les patients susceptibles de mal tolérer un certain degre d’hypoxémie en cours de chirurgie.