Sports participation in patients with implantable cardioverter-defibrillators.

The safety of sports participation for patients with implantable cardioverter-defibrillators (ICDs) is not yet defined, and current recommendations in both Europe and the US restrict these patients from competative sports more vigorous than golf or bowling. Postulated risks include increased frequency of arrhythmias, inability of the ICD to terminate ventricular arrhythmias during the metabolic changes accompanying extreme exercise, injury to the patient, or damage to the ICD system. However, survey data suggest that many ICD patients do participate in sports, and risks may be fewer than postulated. Ongoing research will better delineate the risks of sports for patients with ICDs.

Day-to-day reproducibility of mental stress-induced abnormal left ventricular function response in patients with coronary artery disease and its relationship to autonomic activation.

BACKGROUND: Mental stress (MS) results in left ventricular (LV) dysfunction in approximately half of the patients with symptomatic coronary artery disease (CAD) and is an adverse prognostic sign. The reproducibility of various MS tasks in inducing LV dysfunction and its relationship to autonomic activation in patients with CAD are not known. We studied the reproducibility on different days of 3 commonly used MS tasks on LV ejection fraction (LVEF), heart rate, blood pressure, and rate-pressure product and the relationship of reproducibility to autonomic activation as determined by heart rate variability in patients with chronic stable angina. METHODS AND RESULTS: Ten patients with CAD and exercise-induced ischemia who had abnormal LVEF responses to at least one MS task from a battery of MS tasks (mental arithmetic, anger recall, and color Stroop test) while undergoing continuous ambulatory Holter and LV function monitoring underwent a second MS testing 4 to 8 weeks later, with no change in clinical status or cardiac medications in the interim. Autonomic tone was determined from indexes of heart rate variability (high frequency [HF] for parasympathetic activity and low frequency [LF] and low frequency/high frequency ratio [LF/HF] for sympathetic activity). MS tasks resulted in a small increase in heart rate (P <.0001), a modest increase in systolic blood pressure (P <.0001) and the rate-pressure product (P <.0001), and a small but statistically significant increase in LF (P <.002) and LF/HF (P <.0001), but no change in HF compared with baseline. These changes were highly reproducible over the 2 studies. With a fall in LVEF of 5% or greater considered as indicative of an MS-positive task, anger recall was the most effective and reproducible MS task in inducing LV dysfunction. MS-positive tasks were associated with a greater increase in systolic blood pressure (P =.005). Anger recall resulted in a trend toward a higher increase in systolic blood pressure (P =.08) than the other MS tasks. In MS tasks with inconsistent LVEF responses in the 2 studies (LV dysfunction present in one study but not in the other), there was significant parasympathetic withdrawal (P =.02) in MS-negative tasks but no difference in sympathetic activation. On the other hand, in MS tasks with consistent LV dysfunction on both occasions, there was no difference in parasympathetic or sympathetic activation. MS-positive tasks were not accompanied by chest pain or ST depression. CONCLUSIONS: Of the commonly used MS tasks, anger recall produces LV dysfunction with the highest frequency and is the most reproducible task when retested 4 to 8 weeks later in patients with CAD. These data are relevant for planning studies of the effects of therapeutic interventions on MS-induced LV dysfunction.

Laparoscopic intraperitoneal onlay polytetrafluoroethylene mesh repair (IPOM) for inguinal hernia during spinal anesthesia in patients with severe medical conditions.

In patients with severe pulmonary disease, laparoscopic techniques are not advised. The authors report their preliminary experience with laparoscopic intraperitoneal onlay polytetrafluoroethylene mesh repair for inguinal hernia during spinal anesthesia in patients with chronic obstructive pulmonary disease. Spinal anesthesia was performed using hyperbaric bupivacaine (3-3.5 mL) injected at L2-L3. If necessary, additive opioid therapy was administered. Under low-pressure pneumoperitoneum (10 mm Hg), polytetrafluoroethylene mesh was stapled securely on the posterior inguinal wall to spare epigastric and iliac vessels. Fifteen patients underwent surgery. Median age was 62 years. All patients were classified American Society of Anesthesiologists physical status III/IV. Mean forced expiratory volume in the first second was 1.1 L/s. Median operating time was 20 minutes. Postoperative recovery was uneventful for all patients. The average duration of hospital stay was 1.5 days. Seroma or hematoma was not noted. Six-month follow-up did not show recurrence or infection. This technique is an effective method of repair of inguinal hernia in patients with severe chronic obstructive pulmonary disease, and it provides a maximum of comfort.

Plasmapheresis combined with continuous venovenous hemofiltration in surgical patients with sepsis.

OBJECTIVE: To examine the effect of continuous venovenous hemofiltration (CVVHF) combined with plasmapheresis (TPE) in critically ill surgical patients after treatment of the septic focus. DESIGN: Observational pilot study. SETTING: University teaching hospital intensive care unit. INTERVENTIONS: TPE and CVVHF were administered 24 h after surgical and/or interventional treatment of septic focus. Arterial blood pressure, cardiac output, and systemic vascular resistance values were monitored. We examined the effect of the combined extracorporeal detoxification on outcome related to age, morbidity, organic failure rate, and initial APACHE II score. MEASUREMENTS AND RESULTS: Forty-three patients with sepsis were treated; 19 received TPE in combination with CVVHF, and 24 did not receive extracorporeal therapy. Overall mortality was 44.2%. In the therapy group mortality was lower (42.1 vs. 45.8%), but the primary organic failure rate was higher. The relationship between mortality and age was similar in the two groups. There was also no difference between the groups in the course of scores on APACHE II, multiple-organ failure, and sepsis severity. Only patients with an initial APACHE II score of 21-25 had a significant reduction in mortality after combined extracorporeal detoxification. Mortality of 17% in TPE/CVVHF patients with single- (pulmonary) and double-organ failure (renal/pulmonary) was significantly lower (P < 0.0001) than in untreated patients. CONCLUSIONS: Reduction in mortality in single- and double-organ failure was as high as 28% in septic patients with combined extracorporeal detoxification. A prospective randomized trial in sepsis and double-organ failure should be projected.

Management of arrythmias.

The management of arrhythmias in elderly patients with congestive heart failure, including atrial fibrillation, ventricular tachyarrhythmias, and bradyarrhythmias, is described. Patients with atrial fibrillation can be treated with rate control anticoagulation for stroke prevention or by attempt at cardioversion and maintenance of sinus rhythm. Elderly patients remaining in atrial fibrillation benefit from anticoagulation provided that no contraindication exists. In patients surviving malignant ventricular arrhythmias, defibrillator implantation is beneficial in elderly patients with heart failure. Prognosis and treatment of nonsustained arrhythmias depends on the presence of underlying cardiac abnormalities. In the healthy elderly population, treatment is not indicated. In patients with coronary artery disease, decreased ejection fraction, and nonsustained ventricular tachycardia, electrophysiology can further stratify risk, and defibrillator implantation can improve survival if arrhythmias are induced. This benefit is as great in elderly patients as in younger patients. Symptomatic bradycardias are increasingly common with advancing age. Symptoms are improved with pacing, with maximum benefit from physiologic rather than ventricular pacing. Although the elderly population poses a unique challenge when faced with arrhythmias, an active approach not only saves lives but also reduces morbidity.

Destabilizing effects of mental stress on ventricular arrhythmias in patients with implantable cardioverter-defibrillators.

BACKGROUND: The incidence of sudden cardiac death increases in populations who experience disasters such as earthquakes. The physiological link between psychological stress and sudden death is unknown; one mechanism may be the direct effects of sympathetic arousal on arrhythmias. To determine whether mental stress alters the induction, rate, or termination of ventricular arrhythmias, we performed noninvasive programmed stimulation (NIPS) in patients with defibrillators and ventricular tachycardia (VT), which is known to be inducible and terminated by antitachycardia pacing, at rest and during varying states of mental arousal. METHODS AND RESULTS: Eighteen patients underwent NIPS in the resting-awake state (nonsedated). Ten underwent repeat testing during mental stress (mental arithmetic and anger recall). Induced VT was faster in 5 patients (P=0.03). VT became more difficult to terminate in 5 patients during mental stress; 4 required a shock (P=0.03). There was no change in ease of induction with mental stress. There was no evidence of ischemia on ECG or continuous ejection fraction monitoring. Eight patients received a shock in the resting-awake state and did not perform mental stress. Four underwent repeat NIPS after sedation; 3 then had induced VT terminated with antitachycardia pacing. All patients with an increase in norepinephrine of >50% had alterations in VT that required shock for termination (P<0.01). CONCLUSIONS: Mental stress alters VT cycle length and termination without evidence of ischemia. This suggests that mental stress may lead to sudden death through the facilitation of lethal ventricular arrhythmias.

Rab3D, a small GTPase, is localized on mast cell secretory granules and translocates to the plasma membrane upon exocytosis.

Although mast cell secretion has been intensively studied because of its pivotal role in allergic reactions and its advantages as a physiologic model, the molecular composition of the secretory machine is virtually unknown. In view of the guanine-nucleotide dependency of mast cell exocytosis and the participation of Rab3 proteins in synaptic vesicle release, we hypothesized that a Rab3 isoform regulates mast cell secretion. Fragments of Rab3A, 3B, and 3D were cloned from RBL-2H3 mast cells by reverse transcription- polymerase chain reaction (RT-PCR). Northern blot analysis revealed Rab3D transcripts to be relatively abundant, Rab3B substantially less so, and Rab3A and 3C undetectable. By ribonuclease (RNase) protection assay, Rab3D transcripts were at least 10-fold more abundant than those of other isoforms, and by immunoblot analysis, Rab3D protein was at least 60-fold more abundant than that of Rab3B. Rab3D was more abundant in RBL cells than in brain, but the total mass of Rab3 proteins in RBL cells was 10-fold less than in brain. Rab3D only partly colocalized with secretory granules in RBL cells, but fully colocalized in mature peritoneal mast cells. There was a descending concentration gradient of Rab3D from peripheral to central granules, and no cytoplasmic pool was detectable in resting mast cells. Following exocytotic degranulation, Rab3D translocated to the plasma membrane and remained there for at least 15 min. These studies suggest that Rab3D is a component of the regulated exocytotic machine of mast cells, and identify differences between mast cells and neurons in Rab3 expression and trafficking.

Inappropriate sensing of atrial stimuli in patients with third-generation defibrillators and DDD pacemakers.

Although the problem of ICD sensing of paced ventricular stimuli has been resolved by incorporation of VVI pacing into current ICDs, many patients required separate DDD pacemakers. We report a problematic PM-ICD interaction: the inability to prevent sensing of paced atrial stimuli ("atrial sensing") leading to double-counting in DDD-PM-requiring patients with transvenous (TV) ICDs with aggressive autogain sensing (CPI Ventak PRxII or III). Four of eight patients receiving both transvenous DDD PMs and ICDs (CPI Endotak lead, at the RV apex), had atrial sensing, leading to double counting, despite intraoperative testing of multiple atrial locations with an active fixation lead. Five patients had a PRxII/III ICD, four with atrial sensing (80%), and three a PRx without atrial sensing. Patients with atrial sensing were not distinguished by any clinical or device related variable. In patients with atrial sensing (all with heart block), the PM was programmed to VDD mode. No patient has received inappropriate therapy or failed to sense VF in follow-up. In many patients with TV ICDs who required DDD pacing, no atrial position can be found without ICD sensing of atrial stimuli. While in patients with heart block this problem can be circumvented by programming to the VDD mode, in patients with sinus incompetence it may only be resolved by the combination ICD-DDD PM, currently in development.

[Plasma separation combined with CVVHF in septic and SIRS patients]. / Plasmaseparation kombiniert mit CVVHF in Sepsis- und SIRS-Patienten.

In a prospective non-randomized trial, 59 patients with sepsis (n = 43) and SIRS (n = 16) were treated on a surgical intensive care unit. In 22 patients plasmapheresis in combination with continuous venovenous hemofiltration (CVVHF) was administered. Lethality was 56% in the sepsis group; in the therapy group lethality was significantly lower in patients with plasmapheresis, even though in this population the organic failure rate was higher. Finally the dependency of lethality and age was similar in both groups. Lethality at 22% in the plasmapheresis group with double organ failure was significantly lower (P > 0.01) than in controls. Reduction of lethality seemed to be as high as 18% in patients with sepsis, while patients with SIRS did not profit from the additional therapy. A prospective randomized trial in sepsis and double organic failure should be projected.

Initial single-center experience with an advanced third-generation investigational defibrillator.

The CPI PRxII is a recently approved, multitiered implantable cardioverter defibrillator (ICD) that delivers high and low energy biphasic shocks, antitachycardia (ATP) and bradycardia pacing, and stores 2.5 minutes of electrograms from the widely spaced shocking electrodes. The PRxII was implanted in 58 patients at Yale-New Haven Hospital between December 1993 and January 1995. At implant, mean biphasic defibrillation threshold (DFT) in patients with testing to failure was 10 J (1-20). All 36 patients who were candidates for a new transvenous system underwent successful nonthoracotomy implantation. Based on noninvasive predischarge EPS results, 30 patients had > or = 1 VT zone: 21 patients had ATP, 9 others had first shock < or = 5 J. During follow-up, 13 patients had been treated for 379 events (range, 1-127). Of 340 events in a zone with ATP, 97% responded to ATP, 3% required shock. First programmed shock converted all events in a VF zone. Details, including RR intervals, were available for all events in 15 of 17 patients receiving appropriate or inappropriate therapy or diverted shocks. One hundred eleven of 148 available electrograms confirmed VT by morphology, rate, and/or presence of AV dissociation. In nine patients, electrogram data altered therapy through diagnosis of inappropriate or diverted therapy, guidance of detection enhancements, or diagnosis of previously unrecognized VTs. We conclude the PRxII achieves low DFTs that obviate the need for thoracotomy and effectively treats ventricular arrhythmias with ATP and shock, with programming guided by noninvasive electrophysiology. Multiple stored electrograms from widely spaced shocking electrodes greatly enhance diagnostic capabilities, facilitating effective treatment.

[Hyperdynamic hemodynamics following high-dose interleukin 2-interferon alpha therapy in patients with metastatic renal cell carcinoma. Immunotherapy as a clinical sepsis model?]. / Hyperdyname Hämodynamik während hochdosierter Interleukin-2 /Interferon-alpha-Therapie bei Patienten mit metastasiserendem Neiren-zellkarzinom. Immuntherapie als klinisches Sepsismodell?

UNLABELLED: Human recombinant interleukin 2 (IL-2), alone or in combination with other cytokines, is currently under investigation for the immunotherapy of metastatic tumours. Objective responses of 20-35% have been reported in patients with disseminated melanoma and renal cell carcinoma who received high-dose intravenous IL-2 in combination with interferon-alpha (IFN alpha). However, treatment with IL-2 is complicated by a syndrome of life-threatening adverse reactions such as disseminated vascular leakage, fluid retention, severe hypotension, and (reversible) multiple organ dysfunction (MODS). A systemic inflammatory reaction (SIRS/sepsis sepsis-like haemodynamic pattern has been described in patients after IL-2 bolus application alone. Our purpose was to study the haemodynamic changes in patients treated with high-dose IL-2 administered as a constant infusion and in combination with IFN alpha. PATIENTS AND METHODS: Haemodynamic variables were obtained during therapy courses of 11 patients (aged 48 to 71 years, median 61) with metastatic renal cell carcinoma receiving immunotherapy with IL-2/IFN alpha. Therapy consisted in IFN alpha 10 x 10(10) IU/m2 body surface area (BSA) once daily on days 1-5 i.m. on a regular ward, followed by IL-2 as a constant infusion of 18 x 10(6) IU/m2 BSA on days 6-11 in an intensive care unit (ICU). Haemodynamics were first measured after 5 days of IFN alpha application and transfer to the ICU on day 6, a further 24 h after the beginning of IL-2 infusion (day 7), and the end of the therapy course (days 10 and 11). Mean arterial pressure (MAP) was measured noninvasively using an oscillometric device (Dinamap, Critikon). Mixed-venous oxygen saturation (sv O2) was measured using an CO-oxymeter (OSM 3, Radiometer) and peripheral arterial oxygen saturation (psaO2) was recorded continuously with a pulse oximeter (Oxyshuttle, Critikon). In case of haemodynamic instability, stabilisation had priority over invasive haemodynamic measurements, so that nadir values of blood pressure (BP) did not influence mean MAP and are reported separately. Lactate values and criteria for SIRS were obtained before and during IL-2 infusion. Lactate measurements were performed using an enzymatic essay (Abbot FLx). The mean effect size of the haemodynamic values, SIRS criteria, and lactate concentrations during IL-2 infusion (days 6-11) were calculated, and 95% confidence intervals for the effect sizes are indicated. RESULTS: After their daily i.m. injections of IFN alpha, patients had short episodes of fever and tachycardia without significant drops in BP. A few hours after transfer to the ICU and continuous infusion of IL-2, they developed a syndrome of fever, tachycardia and tachypnoea. The haemodynamic values after 5 days of IFN alpha therapy remained in the normal range, whereas those during IL-2 infusion strongly resembled SIRS and sepsis, with a decrease in MAP (98 to 28 mm Hg) and systemic vascular resistance (SVR, 1477 to 805 dyn.s.cm-5) and an increase in cardiac output (cardiac index 2.8 to 4.3 l.min-1.m-2). MAP often had to be stablilized with colloids during the last 48 h of therapy; 5 patients had nadir values below 60 mm Hg, or 30% below basic values in hypertensive patients. Catecholamine therapy became mandatory in 1 patient and therapy had to be discontinued. Surprisingly, some patients already had elevated plasma lactate concentrations after IFN alpha therapy. During IL-2 infusion mean plasma lactate levels increased from 2.3 to 3.2 mmol.l-1 and all patients had lactate concentrations above 2.0 mmol.l-1 at the end of therapy. During the last 48 to 72 h of IL-2 infusion, patients suffered from MODS with altered mental state (7 patients), oliogoanuria (all patients), cardiac dysrhythmias (4 patients), congestive heart failure (1 patient, which led to a second case of therapy interruption), elevated bilirubin (4 patients), and pulmonary dysfunction. In 9 patients supplementary oxygen was necessary when psaO2 fell below 92

[Insertion of a fiber optic catheter into the hepatic veins of patients with multiple organ dsfunction syndrome (MODS)]. / Anlage eines Fiberoptik-katheters in eine Lebervene bei Patienten mit Multiorgandysfunktions-syndrom (MODS) ohne Einsatz bildgebender Diagnostikverfahren.

As it is the driving force in the development of a multiorgan dysfunction syndrome (MODS), the gastro-intestinal region is at the centre of current discussion. Recently, hepatovenous oximetry has been used increasingly to monitor the relationship between oxygen supply and consumption in the splanchnic system. In the present paper we report an exclusively oximetrically controlled catheterisation procedure that can be carried out at the bedside without the use of imaging procedures. In the inferior vena cava a typical venous oxygen saturation profile can be expected. Near the opening of renal veins there is a peak in venous saturation due to the large extent to which the kidneys partake in the cardiac output and their relatively low oxygen consumption. Correspondingly there is a significant drop in saturation in the area around the opening of the hepatic veins. At the right atrium the oxygen saturation increase again due to admixing of more highly saturated blood from the superior vena cava. Taking these physiological facts into consideration it was attempted to find the opening of the hepatic veins into the inferior vena cava using only continuous in vivo oximetry and to insert a hepatovenous catheter. MATERIAL AND METHODS. In 14 patients with postoperative MODS (Apache II score > or = 20) a fibreoptic pulmonary catheter for the continuous evaluation of oxygen saturation was inserted via the inferior vena cava (entrance through the femoral vein). First the catheter was pushed forward into the wedge position in the usual way. Subsequently it was pulled back up to the region of high renal venous saturation. At this point the catheter, now unblocked, was pushed forward again with gentle twisting motions until a distinct decrease in saturation was reached well below the value of the mixed-venous saturation which can be taken as an indication for having entered the hepatic vein. Using a CO oximeter a slowly aspirated blood specimen was taken from the distal line of the catheter and analysed. The placement of the hepatovenous catheter was verified by radiograph of the abdomen. In most cases the catheter had to be readjusted several times before it reached its final position. RESULTS. Of the 14 patients, 13 showed the saturation course in the inferior vena cava that could theoretically be expected. In 12 patients (85.7%) we succeeded in placing the hepatovenous catheter correctly by applying this procedure. The average depth of insertion of the catheter after final positioning was 57 +/- 4 cm. Initial values of hepatovenous saturation (ShvO2) amounted to an average of 35.1 +/- 9.4%. The minimum value was 19%; the maximum ShvO2 came to 59%. DISCUSSION. With the procedure presented it was possible in 12 of 14 patients to position a hepatovenous catheter oximetrically controlled without further means. A precondition for this is a typical saturation profile of the inferior vena cava, which, however, was not found in one of the patients. A possible explanation for this could be an increased shunt volume in the hepatosplanchnicus area, which can lead to high ShvO2 values. For this reason the opening of the hepatic veins could not be recognized by a decrease in saturation using the oximetric procedure. Placement of a catheter was not possible. Future studies on larger groups of patients will be required to show to what extent monitoring of ShvO2 can lead to an efficient therapy specific for this part of the cardiovascular system in patients with sepsis and MODS.

[Use of plasmapheresis in a 62-year-old patient with severe infection]. / Einsatz einer Plasmapherese bei einem 62jährigen Patienten mit schwerer Sepsis.

INTRODUCTION: The elimination of cytotoxic substances from blood as part of sepsis treatment has been controversely discussed so far. The following case report demonstrates the advantages and disadvantages of this therapy strategy. CASE REPORT: A 62-year-old male patient developed a paralytic ileus with wound dissection 3 days after elective sigma resection. A few hours after surgical revision he went into severe sepsis. A controlled ventilation was necessary as well as the use of catecholamines to maintain sufficient mean arterial pressure. Body temperature stayed between 39 and 40 degrees C (rectal). The patient's extremities and body showed severe marmorations due to the pathologic vasal alteration. A laparotomy one day after the operation revealed a massive generalized edema of the bowels without any evidence of insufficient anastomosis. The fulminant septic process could not be stopped with conservative treatment including continuous veno-venous hemofiltration. Under further deterioration of the pulmonary function (signs of beginning ARDS) and the generalized capillary leak syndrome we started plasmapheresis 2 days after operation in order to eliminate high-molecular cytokines. The plasmapheresis was done twice the following 2 days. Under this treatment the septic process was stopped. The pulmonary function and the circulation improved. The disturbed peripheral perfusion normalized. A laparotomy confirmed a significant decrease of the intestine wall edema. Unfortunately we could not repeat plasmapheresis. On the following days the patient worsened again and died 20 days later due to multiorgan failure. DISCUSSION: The temporary improvement during plasmapheresis suggests that the patient might have profited from plasmapheresis-related optimized oxygen delivery, controlled diuresis and decrease of oxygen consumption. In addition we hypothesized that elimination of high-molecular cytokines and toxines contributed to the improvement under plasmapheresis. Using plasmapheresis one has to consider the high costs, risk of infection, and the unexplained mode of action to the mediatory process. Therefore we cannot recommend this treatment in general. Further controlled studies should investigate the therapeutic benefits of plasmapheresis in patients with severe sepsis.

[The use of pulse oximetry in prilocaine induced methemoglobinemia]. / Untersuchungen zum Einsatz der Pulsoxymetrie bei prilocaininduzierter Methämoglobinämie.

During the last 15 years pulse oximetry has become a widely accepted method of monitoring during general and local anaesthesia. Pulse oximeters measuring with two wave-lengths are considerably affected by dyshaemoglobin. At concentrations up to 30%, CO-Hb cannot be distinguished from O2-Hb. Met-Hb, even in low concentrations, leads to a constant error of measurement; some authors recommended exploiting this for estimation of the Met-Hb concentration. To prove the aim of the present study was to test whether this error in measurement can be defined with one formula for different pulse oximeters. PATIENTS AND METHODS. In a prospective, randomized, double-blind study, 171 non-smoking patients with healthy lungs (ASA 1-3) who had received a plexus block for hand surgery were investigated. After premedication with 3.75-15 mg medazolam p.o. each patient received a total of 6 1O2 via a Hudson mask during the investigation. After 10 min the following pulse oximeters were put on the index finger: (1) Ohmeda BIOX 3700e, (2) Critikon Oxyshuttle, (3) Nellcor N 180. Simultaneously a venous blood sample was taken and analysed immediately with a Radiometer OSM3. The procedure was repeated 15, 30, 60 and 120 min after the plexus block. In 41 patients the plexus block was carried out with lidocaine (6 mg/kg body weight) and in 130 patients, with prilocaine (7 mg/kg body weight). RESULTS. There were no significant differences in age, sex and risk groups between the lidocaine and the prilocaine group. In the lidocaine group we were able to show that hyperoxic conditions can be maintained for 2 h with the method described. In the lidocaine group none of the pulse oximeters showed a psO2 less than 99%. Our results show significant differences between the three pulse oximeters. Therefore, in contrast to the convention followed in the literatur, the relation between Met-Hb and psO2 under hyperoxic conditions must be described with different formulas for each pulse oximeter as follows: (1) Ohmeda BIOX 3700e: Met-Hb = (101-psO2).0.6 (r = 0.94); (2) Critikon Oxyshuttle: Met-Hb = (101-psO2).0.7 (r = 0.83); (3) Nellcor N 180: Met-Hb = (101-psO2).0.9 (r = 0.92). DISCUSSION. Our results show that it is not possible to describe the connection between Met-Hb and psO2 for all pulse oximeters with only one formula, but it is possible to set up different formulas with good correlations for each of the three pulse oximeters. The reasons for the different sensitivity are probably the different algorithms used by the manufacturers. In spite of the good correlations we can not recommend Met-Hb estimation by pulse oximetry measurement with two wave-lengths, because the distinction of hypoxia and Met-Hb its not possible when hyperoxic conditions are not stable as they were in our controlled study. A low psO2 measured in patients with normal arterial blood gases can be an indication of Met-Hb, but the exact measurement of dyshaemoglobin is only possibly by using a co-oximeter.

[Postoperative bilateral compartment syndrome resulting from prolonged urological surgery in lithotomy position. Serum creatine kinase activity (CK) as a warning signal in sedated, artificially respirated patients]. / Postoperatives bilaterales Kompartmentsyndrom der Unterschenkel nach ausgedehnten urologischen Eingriffen in Steinschnittlage. Serum-Creatin-Kinase-Aktivität (CK) als Warnsignal bei analgosedierten Beatmungspatienten.

We report two cases of compartment syndrome of the lower leg that occurred in male patients aged 62 and 57 years, respectively, after 10 and 12-h urological surgery in the lithotomy position. During sedation and mechanical ventilation creatine kinase (CK) activity of more than 8,000 U/l was found in both patients. After extubation, clinical symptoms of the compartment syndrome were found. On the 1st day after surgery patient 2 underwent fasciotomy of both lower legs (Fig. 2). No lasting neurologic defects were observed. Patient 1 was treated by fasciotomy on the 4th postoperative day after paresis of the peroneal nerve had developed in the left lower leg. This paresis had shown no tendency to regression when the patient left hospital. On phlebography, both patients showed blockage of the deep lower leg veins up to the knee. DISCUSSION. The compartment syndrome is a rare but serious complication resulting from prolonged surgery in the lithotomy position. Symptoms are neuromuscular lesions of the affected limb. Severe complications of the compartment syndrome are acute renal failure resulting from myoglobin residues in the tubules, electrolyte disturbances, and disorders of acid-base balance. A decrease in perfusion due to the elevated position of the legs, on the one hand, and the impeded venous back-flow due to the positioning on the other are discussed. While positioning the legs, it is important to ensure that the lower legs are lifted only slightly above left atrial level. When rehabdomyolysis occurs, serum CK activity increases. CK values of over 2,000 U/l after surgery may be considered a warning sign in ventilated and sedated patients, in whom early clinical symptoms of the compartment syndrome such as pain and paresthesias cannot be ascertained. Frequent and regular checks of these parameters starting shortly after surgery are recommended. A thorough examination of the lower legs and, if necessary, measurement of the tissue pressure in the compartment should follow. The deep veins of the legs should be checked by phlebography. In cases of verified compartment syndrome, early fasciotomy is the best choice of therapy, because neuromuscular defects are known to be irreversible after 12 to 24 h. Enforced diuresis is recommended in order to avoid renal complications.

Circadian variation of sustained ventricular tachycardia in patients with coronary artery disease and implantable cardioverter-defibrillators.

BACKGROUND: While previous studies using epidemiological data and ambulatory ECG monitoring have shown peak occurrence of sudden death and nonsustained ventricular tachycardia in the morning, none have examined circadian variation of potentially life-threatening ventricular tachycardia (VT), nor has any study observed circadian behavior of any arrhythmias in individuals followed longitudinally. We used the event memory of multiprogrammable implantable cardioverter-defibrillators to evaluate the circadian pattern of sustained VT over time. METHODS AND RESULTS: Data were reviewed from 32 consecutive patients with coronary artery disease and sustained VT who had received the Ventak PRX (CPI, Inc) cardioverter-defibrillator between May 1991 and August 1993 and had experienced at least one episode of VT terminated by their device. Mean follow-up was 14 +/- 7 months. Among the 2558 episodes recorded by the device logs, VT occurrence peaked between 6 AM and noon (P = .007 by ANOVA among four 6-hour time periods). Harmonic regression revealed a morning peak at 9 AM (P < .01). This morning peak occurred in patients with both frequent and infrequent events. Among 21 patients who experienced more than four VT events, 8 (38%) had an AM peak of VT occurrence (> 35% of VT between 6 AM and noon). Neither age, ejection fraction, event frequency, presenting arrhythmia, nor drug therapy distinguished patients who displayed the AM VT peak. CONCLUSIONS: In patients with coronary artery disease, sustained VT displays circadian variation with peak frequency in the morning, similar to that for sudden death. Individual patients who display specific patterns of circadian variation over time can be identified using defibrillator logs. Investigation of circadian variation of other phenomena to elucidate mechanisms of VT should focus on these patients.

[The effect of hyperbilirubinemia on the measurement of oxygenated hemoglobin (O2Hb), carboxyhemoglobin (COHb) and methemoglobin (MetHb) using multiwavelength oximeters in mixed venous blood]. / Einfluss einer Hyperbilirubinämie auf die Messung von oxygeniertem Hämoglobin (O2Hb), Carboxyhämoglobin (COHb) und Methämoglobin (MetHb) mit Mehrwellenlängenoxymetern im gemischtvenösen Blut.

Oximetric measurements are influenced by several mechanisms. Severe jaundice is one of these mechanisms with some clinical interest. In the literature it is pointed out that a high bilirubin concentration may falsify oximetric measurements and is often accompanied by elevated COHb levels. The reason for this phenomenon is thought to be an interference in the absorption spectra of haemoglobin derivatives and bilirubin [2, 3, 4, 10]. In our investigation we attempted to answer the following questions: 1. How do multiwavelength oximeters measure haemoglobin derivatives in different bilirubin concentrations? 2. Do different multiwavelength oximeters give different concentrations of haemoglobin derivatives? METHODS. In 13 patients who developed postoperative jaundice on the intensive care unit, O2Hb, COHb and MetHb were measured in mixed venous blood with two multiwavelength oximeters (OSM3, Radiometer; CO 2500, Ciba-Corning). Bilirubin concentration was measured by the DPD (dichlorphenyldiazonium) method in the central laboratory of our hospital. RESULTS. With increasing bilirubin concentrations, both oximeters measured increasing O2Hb values; the OSM3 consistently showed higher O2Hb concentrations than the CO 2500, with a maximal difference of 2.8% (Fig. 3). Regarding COHb, we saw clear increases in the values with increasing bilirubin concentrations (Fig. 4). The CO 2500 showed higher COHb values than the OSM3 (average 1.54 +/- 0.3%). The findings regarding MetHb differed. The CO 2500 showed increasing MetHb values as the bilirubin concentration increased (Fig. 5). All measurements exceeded normal values above a bilirubin concentration of 17 mg/dl. The OSM3, however, measured constant MetHb values which did not depend on jaundice. CONCLUSIONS. 1. The in vitro measurement of haemoglobin derivates by multiwavelength oximeters is influenced by hyperbilirubinaemia. This is caused by an interference between the light absorption spectra of the haemoglobin derivates and of bilirubin and by the increasing development of endogenous CO in the haem metabolism during severe jaundice (Fig. 7). 2. With increasing bilirubin levels, a lower O2Hb is measured with the CO 2500 than with the OSM3. 3. We also see increasing COHb values with rising bilirubin concentrations. 4. With increasing bilirubin levels the MetHb concentration measured with the CO 2500 rises, while the OSM3 gives constant MetHb values. 5. In severe jaundice the O2Hb values measured with multiwavelength oximeters are not identical with the real blood concentration of this haemoglobin derivative. In this situation multiwavelength oximeters cannot be used as a reference method for in vivo oximetric systems such as pulse oximeters or fibreoptic pulmonary artery catheters.