Commemorating 50 years since the first heart transplantation in Bratislava - Czechoslovakia

The first human-to-human heart transplantation in Czechoslovakia, and the 25th transplantation in the world, was performed in Bratislava, the second largest city in Czechoslovakia on July 9, 1968. The operation was carried out by a team led by Professors Karol Siska and Ladislav Kuzela at the second Surgical Clinic at the Comenius University of the Medical Faculty in Bratislava, Partizanska Street-only seven months after the first heart transplantation performed by Dr. Christiaan Barnard in Cape Town. Other members of the team in Bratislava included surgery recipients Siska, Kuzela, Pivkova, Holoman; surgery donors Schnorrer, Kuzela, Holoman; an extracorporeal circulation team of Treger, Carsky, Podolay; anesthesiologists Sobesky and Neumanova; operating room nurses Machkova, Homerova, Kralova, and operating room laboratory technician Malinova. The donor was P.V., a 46-year-old man, who suffered from a deadly brain trauma. The recipient was S.H., a 54-year-old woman with a failing heart, heavily affected diseased lungs, kidneys and liver. Her heart began to work, but lasted only for five hours. (Additional members of the team, Prof. Simkovic and Drs. Silvay and Sujansky were in the USA at the moment of transplantation, in Houston and New York, subsequently) (Tab. 1, Fig. 2, Ref. 62). Keywords: first heart transplantation in Bratislava, 2nd Surgical Clinic at the Comenius University.

Characterization of surgical cardiac tumors

OBJECTIVE

The primary tumors of the heart are extremely rare. There are divided to benign, malignant and metastatic. Metastatic cardiac tumors are more common.

METHODS

The incidence in contemporary echocardiographic series is reported at a higher frequency of 0.15%. 75% of cardiac tumors are benign; approximately half of these are cardiac mommas. The malignant cardiac tumors are mostly histopathologically undifferentiated, followed by leiomyosarcomas and angio-sarcomas.

RESULTS

Cardiac tumors have a wide range of unique clinical presentation. Even the most benign and smallest tumor can lead to significant morbidity and mortality. The clinical presentations of the primary cardiac tumors are due to: blood flow obstruction, tumor embolization and constitutional symptoms. Clinical presentations can be varied and may resemble coronary disease, pericarditis, cardiomyopathy or valve malfunction. The recent technological advances in non-invasive imaging modalities such as echocardiography and cardiac magnetic resonance imaging is rapidly increases the early diagnosis and management approach.

CONCLUSION

In this review we aim to summarize the characterization of the most common cardiac tumors. Early recognition and treatment provided the best results (Tab. 2, Fig. 6, Ref. 66).

Practice variations in the conduct of hypothermic circulatory arrest for adult aortic arch repair: focus on an emerging European paradigm

INTRODUCTION

Hypothermic circulatory arrest for adult aortic arch repair is still high-risk. Despite decades of clinical experience, significant practice variations exist around the world. These practice variations in hypothermic circulatory arrest may offer multiple opportunities to improve practice. The hypothesis of this study was that the current conduct of adult hypothermic circulatory arrest in Europe has significant variations that might suggest opportunities for risk reduction.

METHODS

An adult hypothermic circulatory arrest questionnaire was developed and then administered at thoracic aortic sessions at international conferences during 2010 in Beijing and Milan. The data was collected, abstracted and analyzed.

RESULTS

The majority of the 105 respondents were anesthesiologists based in Europe and China. The typical adult aortic arch repair in Europe was with hypothermic circulatory arrest at moderate hypothermia utilizing bilateral antegrade cerebral perfusion, typically monitored with radial arterial pressure and cerebral oximetry. Brain temperature was frequently measured at distal locations. The preferred neuroprotective agents were steroids, propofol and thiopental.

CONCLUSIONS

The opportunities for outcome improvement in this emerging European paradigm of tepid adult aortic arch repair include nasal/tympanic temperature measurement and adoption of unilateral antegrade cerebral perfusion monitored with radial artery pressure and cerebral oximetry. The publication of an evidence-based consensus would enhance these practice-improvement opportunities.

Current conduct of deep hypothermic circulatory arrest in China

INTRODUCTION

Deep hypothermic circulatory arrest for adult aortic arch repair is still associated with significant mortality and morbidity. Furthermore, there is still significant variation in the conduct of this complex perioperative technique. This variation in deep hypothermic circulatory arrest practice has not been adequately characterized and may offer multiple opportunities for outcome enhancement. The hypothesis of this study was that the current practice of adult deep hypothermic circulatory arrest in China has significant variations that might offer therapeutic opportunities for reduction of procedural risk.

METHODS

An adult deep hypothermic circulatory arrest questionnaire was developed and then administered at a thoracic aortic session at the International Cardiothoracic and Vascular Anesthesia Congress convened in Beijing during 2010. The data was abstracted and analyzed.

RESULTS

The majority of the 56 respondents were anesthesiologists based in China at low-volume deep hypothermic circulatory arrest centers. The typical aortic arch repair had a prolonged deep hypothermic circulatory arrest time at profound hypothermia. The target temperature for deep hypothermic circulatory arrest was frequently measured distal to the brain. The most common perfusion adjunct was antegrade cerebral perfusion, typically monitored with radial arterial pressure and cerebral venous oximetry. The preferred neuroprotective agents were steroids and propofol.

CONCLUSIONS

The identified opportunities for outcome improvement in this delineated deep hypothermic circulatory arrest model include nasal/tympanic temperature measurement and routine cerebral perfusion, preferably with unilateral antegrade cerebral perfusion monitored with radial artery pressure and cerebral oximetry. Development and dissemination of an evidence-based consensus would enhance these practice-improvement opportunities.

John Heysham Gibbon and the 60th anniversary of the first successful heart-lung machine: brief notes about the development of cardiac surgery in Europe and Slovakia

The development of the heart-lung machine and its first successful clinical application in 1953 was the culmination of Dr. Gibbon's lifetime research project. Despite many technical obstacles, financial problems, and discouragement from colleagues, his goal was achieved after twenty tedious years of tireless work. Posteriorly, his academic contribution established him as a leader and pioneer in the field of cardiac surgery. Parallel to his achievement and Dr. Kirklin's surgical experience, several authors around the world attempted open-heart surgery with the heart-lung machine, particularly in Europe. In Eastern Europe and particularly in the former Czechoslovakia, the lack of access to foreign medical literature forced a group of emerging young physicians from the Second Department of Surgery at Comenius University to furtively collect data on the topic. After building the Simkovic-Bolf heart-lung machine, the first successful open-heart surgery with the new device was performed only 5 years after Dr. Gibbons' experience (Tab. 1, Fig. 4, Ref. 22).

Mortality reduction in cardiac anesthesia and intensive care: results of the first International Consensus Conference

There is no consensus on which drugs/techniques/strategies can affect mortality in the perioperative period of cardiac surgery. With the aim of identifying these measures, and suggesting measures for prioritized future investigation we performed the first International Consensus Conference on this topic. The consensus was a continuous international internet-based process with a final meeting on 28 June 2010 in Milan at the Vita-Salute University. Participants included 340 cardiac anesthesiologists, cardiac surgeons, and cardiologists from 65 countries all over the world. A comprehensive literature review was performed to identify topics that subsequently generated position statements for discussion, voting, and ranking. Of the 17 major topics with a documented mortality effect, seven were subsequently excluded after further evaluation due to concerns about clinical applicability and/or study methodology. The following topics are documented as reducing mortality: administration of insulin, levosimendan, volatile anesthetics, statins, chronic β-blockade, early aspirin therapy, the use of pre-operative intra-aortic balloon counterpulsation, and referral to high-volume centers. The following are documented as increasing mortality: administration of aprotinin and aged red blood cell transfusion. These interventions were classified according to the level of evidence and effect on mortality and a position statement was generated. This International Consensus Conference has identified the non-surgical interventions that merit urgent study to achieve further reductions in mortality after cardiac surgery: insulin, intra-aortic balloon counterpulsation, levosimendan, volatile anesthetics, statins, chronic β-blockade, early aspirin therapy, and referral to high-volume centers. The use of aprotinin and aged red blood cells may result in increased mortality.

Mortality reduction in cardiac anesthesia and intensive care: results of the first International Consensus Conference

BACKGROUND

There is no consensus on which drugs/techniques/strategies can affect mortality in the perioperative period of cardiac surgery. With the aim of identifying these measures, and suggesting measures for prioritized future investigation we performed the first international consensus conference on this topic.

METHODS

The consensus was a continuous international internet-based process with a final meeting on June 28th 2010 in Milan at the Vita-Salute University. Participants included 340 cardiac anesthesiologists, cardiac surgeons and cardiologists from 65 countries all over the world. A comprehensive literature review was performed to identify topics that subsequently generated position statements for discussion, voting and ranking.

RESULTS

Of the 17 major topics with a documented mortality effect, seven were subsequently excluded after further evaluation due to concerns about clinical applicability and/or study methodology. The following topics are documented as reducing mortality: administration of insulin, levosimendan, volatile anesthetics, statins, chronic beta-blockade, early aspirin therapy, the use of preoperative intra-aortic balloon counterpulsation and referral to high-volume centers. The following are documented as increasing mortality: administration of aprotinin and aged red blood cell transfusion. These interventions were classified according to the level of evidence and effect on mortality and a position statement was generated.

CONCLUSION

This international consensus conference has identified the non-surgical interventions that merit urgent study to achieve further reductions in mortality after cardiac surgery: insulin, intra-aortic balloon counterpulsation, levosimendan, volatile anesthetics, statins, chronic beta-blockade, early aspirin therapy, and referral to high-volume centers. The use of aprotinin and aged red blood cells may result in increased mortality.

Cerebral oximetry in cardiac and major vascular surgery

We describe the development and current applications of cerebral oximetry (based on near-infrared reflectance spectroscopy) that can be used during cardiac and major vascular surgery to determined brain tissue oxygen saturation. There are presently three cerebral oximetry devices with FDA approval in the United States to measure and monitor cerebral tissue oxygen saturation. 1. INVOS (Somanetics Corporation, Troy, MI - recently COVIDIEN, Boulder, CO); FORE-SIGHT (CAS Medical Systems, Inc. Branford, CT); EQUANOX (Nonin Medical Inc.Minnesota, MN). All devices are portable, non-invasive and easy to use in operating room and intensive care unit. The data provided in these communication may provided information for improvement of perioperative neuromonitoring techniques, and may be crucial in the design of future clinical trials.

Day admission for thoracic aortic surgery

Elective cardiac surgical patients can be admitted on the morning of the operation. The day admission surgery is safe with optimal care for patients and provides an economical benefit. In our institution if immediate surgery is not required, patients are entered into program for serial follow up. An elective aortic intervention for open surgical or endovascular surgery is recommended when the risk of aortic rupture outweighs the risk of surgery. Patients are seen 3 to 7 days prior of day admission surgery in preoperative clinic. On the morning of surgery, the patient undergoes a reassessment to ensure no interval changes have occurred. We hereby describe our three years experience with 350 patients were referred from the Aortic Aneurysm Surveillance Program. We believe that not only patients, but all medical personal benefit from a complete preoperative evaluation of these complicated patients and this creates harmony during the entire hospitalization!

Cardiac anesthesia and surgery in geriatric patients: epidemiology, current surgical outcomes, and future directions

The mean life expectancy of the population of the United States is projected to increase from 78.3 years at present to over 81 years in 2025, with a concomitant increase in the percentage of the population over the age of 75 years. Elderly patients are more likely to present with valvular and coronary artery disease than younger patients, and as better perioperative management contributes to improving post-operative outcomes and lower referral thresholds, very elderly patients form an increasingly large proportion of the cardiac surgical population. This article summarizes the impact of age-related pathophysiologic changes on patients' response to cardiac surgery and anesthesia, outlines useful perioperative strategies in this age group, and reviews the literature on outcomes after valvular and coronary in elderly patients.

Descending thoracic and thoracoabdominal aneurysm

The low incidence of permanent spinal cord injury in our most recent cohort (Group II) of patients suggests that serial sacrifice of intersegmental vessels, careful monitoring of spinal cord function are effective in preventing paraplegia after descending thoracic and thoracoabdominal aneurysm operations. Updated anesthetic and postoperative care minimized overall mortality risk. (Ref. 9.)

Factors that influence early extubation: bleeding

Excessive bleeding after cardiac surgery is an important factor that can prevent early extubation. Hemostatic derangement is well recognized to be associated with cardiopulmonary bypass, with many possible contributing factors resulting in coagulation defects and fibrinolytic pathway activation. Measures to optimize hemostasis are critical when managing patients for whom early extubation and hospital discharge are goals. The intraoperative evaluation of the hemostatic system with tests like the thrombelastogram and the use of therapeutic agents such as aprotinin are simple, safe, and effective methods of achieving these goals.

Hemostasis in aortic and cardiothoracic surgery

Hemostasis abnormalities in cardiovascular and aortic surgery remain a major source of morbidity and mortality in patients undergoing such complex procedures. The need for frequent transfusions of red cell and other blood products increases risks and costs to patients and institutions providing patient care. Specifically in cardiovascular and aortic surgery, the nature of the surgery is, at best, semi-elective, and careful preparation to preserve the hemostatic mechanisms of the body is essential. Contact of blood with the extracorporeal circuit induces a hemorrhagic diathesis through a variety of different mechanisms. Dilution of the patient's blood volume by the extracorporeal circuit prime causes depletion of platelets and coagulation factor levels. Aorto intimal disease initiates fibrinolysis by the release of tissue plasminogen activator. Due to the numerous etiologies of bleeding, a combination of blood conservation strategies is suggested. The ideal combination of interventions has yet to be determined and is currently dependent on patient variables, physician and institutional practices, and economic pressures.

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.

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.

Comparison of propofol versus ketamine for anesthesia in pediatric patients undergoing cardiac catheterization

Intravenous propofol was compared with ketamine in 20 pediatric patients undergoing cardiac catheterization. The study patients were randomly assigned to treatment groups so that 10 patients received ketamine and 10 patients received propofol. The hemodynamic responses and recovery characteristics of the two groups were compared. On induction of anesthesia, seven patients in the propofol group experienced a transient decrease in mean arterial blood pressure greater than 20% of baseline accompanied by mild arterial desaturation in four patients. Only one patient in the ketamine group experienced such a decrease in arterial blood pressure. This was the only significant difference (P less than 0.05) in hemodynamic effects between the two groups. Time to full recovery (mean +/- SD) was significantly less in the propofol group (24 +/- 19 min vs 139 +/- 87 min, P less than 0.001). In the ketamine group only, significant correlations (P less than 0.05) included time to full recovery with duration of anesthetic (r = 0.71) and time to full recovery with total drug dose per kilogram (r = 0.82). The authors conclude that propofol anesthesia is a practical alternative for pediatric patients undergoing elective cardiac catheterization and may be preferable to ketamine because of the significantly shorter recovery time.

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 post-induction, and at one, three, five and ten minutes after tracheal intubation. Tachycardia and hypertension (greater than 20% increases from awake baseline values) were treated with esmolol, 250 micrograms.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 less than 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 II) had hypertensive responses to tracheal intubation. Preoperative hypertension (mean arterial pressure greater than or equal to 100 mmHg) was a predictor (P less than 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.

Lower esophageal contractility: a technique for measuring depth of anesthesia

Until recently, there has been no simple, accurate, reliable technique for monitoring depth of anesthesia during surgery. A system that measures lower esophageal contractility (LEC) has been designed for this purpose. The system consists of a monitor and a disposable esophageal probe equipped with provoking and measuring balloons. Since the motor control of the esophagus is directly controlled by the brain stem, LEC was postulated to be a reflection of the anesthetic state of the patient. Multiple-center clinical studies have shown that LEC correlates significantly (p less than 0.005) with concentrations of volatile anesthetic agents and patient responses to surgical stimulation. Closed-loop anesthetic techniques have been developed at several institutions based on LEC and hemodynamic parameters. Lower esophageal contractility has been shown to be an accurate monitor of anesthetic depth for a variety of surgical procedures and anesthetic techniques.

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

In nearly 25 years of clinical experience, the benefits and limitations of ketamine analgesia and anaesthesia have generally been well-defined. The extensive review of White et al. and the cardiovascular review of Reves et al. are broad in their scope and have advanced the understanding of dissociative anaesthesia. Nevertheless, recent research continues to illuminate different aspects of ketamine pharmacology, and suggests new clinical uses for this drug. The identification of the N-methylaspartate receptor gives further support to the concept that ketamine's analgesic and anaesthetic effects are mediated by separate mechanisms. The stereospecific binding of (+)ketamine to opiate receptors in vitro, more rapid emergence from anaesthesia, and the lower incidence of emergence sequelae, make (+)ketamine a promising drug for future research. Clinical applications of ketamine that have emerged recently, and are likely to increase in the future, are the use of oral, rectal, and intranasal preparations for the purposes of analgesia, sedation, and anaesthetic induction. Ketamine is now considered a reasonable option for anaesthetic induction in the hypotensive preterm neonate. The initial experience with epidural and intrathecal ketamine administration has not been very promising but the data are only preliminary in this area. The use of ketamine in military and catastrophic settings is likely to become more common. The clinical availability of midazolam will complement ketamine anaesthesia in several ways. This rapidly metabolized benzodiazepine reduces ketamine's cardiovascular stimulation and emergence phenomena, and does not have active metabolites. It is dispensed in an aqueous medium, which is usually non-irritating on intravenous injection, unlike diazepam. The combination of ketamine and midazolam is expected to achieve high patient acceptance, which never occurred with ketamine as a sole agent. Finally, it is necessary to point out the potential for abuse of ketamine. While ketamine is not a controlled substance (in the United States), the prudent physician should take appropriate precautions against the unauthorized use of this drug.

Open heart surgery in patients in the eighth and ninth decades of life

One hundred fifty-one patients aged 70-89 years underwent a variety of open heart surgical procedures during a period of 1 year. We divided these patients into two groups: Group A was comprised of 127 patients between 70 and 79 years of age. In group B, 24 patients were between 80 and 89 years of age. These patients underwent elective open heart surgery. Information was retrieved retrospectively from the computerized data pool of the cardiothoracic registry in our institution. Statistical analysis in these two groups revealed no significant differences in any of the evaluated factors. We concluded that age should not be a contraindication for cardiac operations.

Response of lower esophageal contractility to changing concentrations of halothane or isoflurane: a multicenter study

A multiple-center study was performed to determine the relationship between lower esophageal contractility, clinical signs, and anesthetic concentration as expressed by minimum alveolar concentration (MAC). One hundred four American Society of Anesthesiologists Class I through III patients were exposed to isoflurane (with and without nitrous oxide) or halothane in concentrations of 0.5, 1.0, and 1.5 MAC. Heart rate and systolic blood pressure were continuously monitored. Both the amplitude and frequency of spontaneous and provoked lower esophageal contractions were measured in situ by using a 24-F probe equipped with provoking and measuring balloons. Combined results demonstrated statistically significant correlations (P less than 0.001) between lower esophageal contractility and MAC. Spontaneous lower esophageal contractions decreased from 1.10 +/- 0.12 (SEM) contractions per minute (0.5 MAC) to 0.42 +/- 0.05 (1 MAC) to 0.18 +/- 0.05 (1.5 MAC). Provoked lower esophageal contractility values decreased from 45 +/- 4 mm Hg (0.5 MAC) to 29 +/- 3 (1 MAC) to 19 +/- 2 (1.5 MAC). Heart rate changes did not correlate with MAC, and systolic blood pressure correlated in only one of three centers. Intracenter and intercenter analyses failed to demonstrate a significant relationship between lower esophageal contractility and heart rate or systolic blood pressure. No intracenter differences in either amplitude or frequency of lower esophageal contractions were observed, despite differences in volatile agents, induction techniques and agents, patient populations, and durations of anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of temperature, mean arterial pressure, and cardiopulmonary bypass flows on somatosensory evoked potential latency in man

Median nerve somatosensory evoked potentials were recorded in 21 patients undergoing cardiac surgical procedures utilizing cardiopulmonary bypass, in order to establish the effects of hypothermia, reductions in mean arterial pressure, and alterations in cardiopulmonary bypass flows on evoked potential latency. Induction and maintenance of anesthesia with fentanyl caused a significant prolongation of latency of the first cortical peak. Temperature changes were linearly correlated with changes in latency for peaks recorded from Erb's point (r = -0.843, p less than 0.01) and the contralateral cortex (r = 0.843, p less than 0.01). There was no significant effect of mean arterial pressure or cardiopulmonary bypass flow reductions on latencies under the conditions of this study. Our results emphasize the importance of monitoring peripheral and first cortical peak latencies in evaluating somatosensory evoked potentials. It is suggested that peak latency prolongations beyond those predicted by temperature alterations may be indicative of hypoperfusion.

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 PaO2 as 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 administer 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 PaO2 in excess of 9.31 kPa (70 torr) was achieved with ketamine and FIO2 1.0 as well as an increase in shunt fraction from 25.9 per cent (FIO2 0.5) to 36.0 per cent (FIO2 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.

A comparison of the effects of continuous ketamine infusion and halothane on oxygenation during one-lung anaesthesia in dogs

It has been shown that a continuous infusion of ketamine during one-lung anaesthesia combined with a 50 per cent oxygen-curare anaesthetic technique will provide consistently lower shunt fraction and higher Pao2 compared with halothane under the same experimental conditions. Because no additional factor was observed which could account for these changes and because the responses of the animals to the two anaesthetic agents were similar--the only difference being a different initial set point--the experimental model may be considered adequate. In the authors' view the difference in shunt fractions may be attributed to a more stable hypoxic reflex during ketamine anaesthesia. Further experimentation will be necessary to fully exclude the possibility of sequence-related changes affecting some of these results and to determine whether or not certain groups of dogs respond in a qualitatively different fashion.

The cerebral function monitor during open-heart surgery

Open-heart surgery has entered the third decade of its existence. The period has demonstrated increased patient safety during and after open-heart surgery due to the employment of simple and reliable monitoring techniques. The monitoring of the function of the brain has not kept pace with these advances. Electroencephalographic (EEG) method is impractical for routine use in the operating room and in the intensive care unit. The cerebral function monitor (CFM) offers simplified continuous monitoring and interpretation of cerebral electrical activity (integrated EEG) in the clinical situation. The unit displays a two channel tracing, one representing cerebral activity and a second indicating electrode impedance artefacts. The early changes seen in addition to other conventional monitoring of the electrocardiogram, blood pressures, pulse rate, etc. offers information especially pertinent to open-heart surgery. It would appear that there is a place in anesthetic practice during and after cardiopulmonary bypass for the routine use of the CFM to supplement existing monitoring for the safer conduct of open-heart surgery. This study analyzes the value of a cerebral function monitor in 112 patients undergoing open-heart surgery.