Regional cerebral blood flow and cellular environment in subarachnoid hemorrhage: A thermal doppler flowmetry and microdialysis study.

BACKGROUND: Cerebral microdialysis enables assessment of regional metabolic physiology and provides biomarkers for clinical correlation in critical conditions, such as subarachnoid hemorrhage (SAH). The aim of our current study was to investigate the correlation between regional cerebral blood flow and microdialysis parameters (glucose, lactate, glycerol, pyruvate concentrations, and lactate/pyruvate metabolic ratio) in patients with SAH. MATERIALS AND METHODS: Twenty-one patients with SAH were enrolled in our retrospective study. Cerebral blood flow (CBF) based on thermal diffusion methodology, the thermal coefficient K, and microdialysis biochemical markers were recorded. The duration of the brain monitoring was 10 days. RESULTS: Microdialysis glucose concentration was inversely related to the cerebral temperature and to the L/P ratio. Furthermore, it was positively correlated to all other microdialysis parameters but glycerol. The K coefficient was strongly and positively correlated with the temperature and marginally with the CBF. The L/P ratio was positively correlated with glycerol, while it was inversely correlated with the CBF. Patients who died had elevated L/P ratio and K coefficient compared to the survivors in our series. CONCLUSIONS: Thermal conductivity coefficient may change over time as cerebral injury progresses and tissue properties alter. These alterations were found to be associated with the microdialysis metabolite concentrations and the CBF itself. The microdialysis biochemical indices of cell stress and death (glycerol, L/P ratio) were positively related to each other, while the measured L/P metabolic ratio was higher among patients who died.

Hybrid procedures for the treatment of multi-focal ipsilateral internal carotid and proximal common carotid or innominate artery lesions.

We report three cases with concomitant ipsilateral proximal common carotid and internal carotid artery stenosis treated in one stage with carotid endarterectomy and retrograde primary stenting of the common carotid artery. The internal carotid artery was clamped during stenting to avoid cerebral embolization. All procedures were successfully completed and all patients remain asymptomatic at 18 months follow up. The one-stage hybrid approach appears to be a safe and effective procedure for the treatment of ipsilateral multifocal significant lesions.

Long-term antiplatelet treatment for innominate vein aneurysm.

Aneurysms of thoracic veins are rare lesions and their therapeutic management is not clearly determined. We present a 60-year old man with an asymptomatic right innominate vein aneurysm. The patient had been operated on 10 years ago for coronary artery bypass and was under antiplatelet treatment. In a retrospective inspection of his chest X-rays, we found that the aneurysm had been existent for at least 10 years. We suggested conservative treatment and over a 5-year follow-up, the patient has remained asymptomatic. Our patient is alive 15 years with thoracic vein aneurysm and antiplatelet treatment.

Hybrid endovascular and open treatment of severe multilevel lower extremity arterial disease.

OBJECTIVE: To evaluate the feasibility and efficacy of simultaneous combined endovascular and open lower extremity arterial reconstruction. DESIGN: Case series study with retrospective analysis of prospectively collected non-randomised data. METHODS: Patients were divided into three groups: group 1 and group 2 included patients who underwent endovascular reconstruction proximal and distal to the site of open reconstruction, respectively, whereas group 3 included patients who underwent open surgery with both proximal and distal endoluminal procedures. Patency analyses were performed using Kaplan-Meier life tables. Univariate and multivariate analyses were used to assess the influence of various risk factors on primary patency. RESULTS: Complete data were obtained from 60 patients who underwent 61 single-step hybrid procedures. Technical and haemodynamic success rates were 100% and 95%, respectively. The perioperative mortality rate was 3%. The primary and assisted-primary patency rates at 12 months were 71% and 98%, respectively. Primary patency rates were lower in group 3 when compared with groups 1 and 2 (log-rank test, p=0.006). The presence of diabetes and dyslipidaemia were independent predictors of decreased primary patency (p=0.003 and p=0.014, respectively). CONCLUSIONS: Hybrid procedures provide an effective treatment management of selected patients with multilevel lower extremity arterial disease. The extent of the disease, diabetes and dyslipidaemia are associated with worse outcome.

The impact of fluid restriction policy in reducing the use of red blood cells in cardiac surgery.

Hemodilution contributes significantly to transfusion requirements in patients undergoing CABG under CPB. We hypothesised that restriction of parenteral fluids in comparison to a liberal fluid administration policy leads to less use of packed red cells in CABG operations supported by cell salvage. After consent and approval, 130 patients operated under equal conditions were assigned prospectively and randomly either for a restrictive protocol for intravenous fluid administration (group A, 65 pts) or not (group B, 65 pts). Transfusion guidelines were common for the two groups. The volumes of intravenous fluids, priming, "extra" volume on pump and cardioplegic solution and the volume of urine were recorded. Net erythrocyte volume loss was calculated. The number of the transfused PRC was analyzed as a continuous variable. "Transfusion" was analyzed as a categorical characteristic. Significant difference existed between groups for the fluids administered intravenously until the initiation of CPB and for fluid balance after CPB. Intraoperatively transfused units were significantly lower in A (0.32 +/- 0.77 vs 1.26 +/- 1.05 u/per pt; p<0.0001). Transfused patients were also significantly lower in A (11/65 vs 44/65; p<0.0001). In both groups, the values of hematocrit were statistically decreased. The greatest difference compared to the preoperative values was observed after CPB (from 40.8 +/- 4.2 to 21.9 +/- 3.6 for A, and from 40.2 +/- 3.7 to 19.7 +/- 3.3 for B ; p<0.0001 for both). For these lowest values, significant difference existed between groups (p<0,001) while the difference in the hematocrit values to the end of operation was insignificant. Transfusion in ICU showed no significant difference among groups. Hours of mechanical ventilation in ICU were ranging from 5 to 29 (mean = 10.0, median = 9) for A and from 5 to 42 (mean = 14.8, median = 10) for B. Length of stay in ICU in nights for group A was ranging from 1 to 10 (mean = 2.7, median = 2) and for group B was ranging from 1 to 6 (mean = 3.5, median = 2). In conclusion, reduction of transfusions in CABG operations is feasible when a restrictive protocol for intravenous fluids is applied.

Catamenial pneumothorax.

Catamenial pneumothorax is a rare entity of spontaneous, recurrent pneumothorax occurring in synchrony with the menstrual cycle. The etiology is not completely known, but in most cases it is associated with thoracic endometriosis and/or diaphragmatic fenestrations. We report a case of a 35-year-old woman with three episodes of catamenial pneumothorax. The surgical findings were thoracic endometriosis and diaphragmatic holes. She underwent resection of the affected part of the diaphragm and pleurodesis via a mini-thoracotomy and videothoracoscopy assistance.

Malpractice issues in modern anaesthesiology.

Medical malpractice has been raised as an important problem in daily practice, while the media and public remain unforgiving to those perceived to have harmed the patients' life. This article highlights important legal issues related to medical malpractice and summarizes the sources and the nature of potential errors in anaesthesiology practice.

The effects of propofol or sevoflurane on free radical production after tourniquet induced ischaemia-reperfusion injury during knee arthroplasty.

BACKGROUND: We studied the effects of anesthesia with propofol or sevoflurane on the production of free oxygen radicals during total knee arthroplasty performed with the use of an ischemic tourniquet by measuring the levels of malondialdehyde (MDA). METHODS: We studied two groups of patients (20 patients in each group) who underwent total knee arthroplasty. To maintain anesthesia we delivered 66% nitrous oxide plus sevoflurane or propofol. Blood samples for the determination of the MDA levels were drawn before the application of the ischemic tourniquet and 5 and 30 minutes after its release. RESULTS: There were no differences between groups in regard to age, weight and duration of the tourniquet application. MDA levels decreased significantly in the propofol group 30 minutes after the release of the tourniquet (1.7 micromol litre(-1) vs 1.57 micromol litre(-1), Friedman's ANOVA, P = 0.007). In contrast, there was a small rise of the MDA levels in the sevoflurane group (1.82 micromol litre(-1) vs 1.96 micromol litre(-1), Friedman's ANOVA, P = 0.007). CONCLUSION: Propofol may have anti-oxidant properties in orthopaedic surgery requiring tourniquet application, but sevoflurane needs further study.

Non-programmed clamping of superior vena cava. The anesthesiologist's Achilles' heel.

This case presentation focuses on the hemodynamic alterations due to acute clamping of superior vena cava (SVC) during a right pneumonectomy for lung cancer and on the alternatives for drug administration. In a 71-yr-old female patient without clinical manifestations of SVC syndrome, this large vein was clamped for 22 minutes for patch placement after sudden and unpredictable hemorrhage. The patient became acutely cyanotic and edematous in the face and upper extremities, arterial blood pressure dropped and the venous pressure in the right internal jugular vein was elevated. Drugs for managing the patient were given endobronchially and via an established right atrium line. Postoperatively, no neurologic deficit was noted. This case demonstrates the difficulties for managing patients without superior vena cava syndrome in which acute, non-programmed intra-operative SVC clamping is performed, as this is followed by systemic and brain hemodynamic deteriorations that may lead to bad outcome.

Coronary sinus venoarterial CO2 difference in different hemodynamic states.

Myocardial metabolic rate and coronary flow are closely related limiting thus the diagnostic value of coronary sinus saturation monitoring as an indicator of flow. Regional venoarterial CO2 gradient was found elevated during low flow in various clinical and experimental conditions, in animals and humans. This study was undertaken to examine the impact of the variations of cardiac mechanical work on veno-arterial CO2 content and partial pressure difference (deltaPCO2) of the coronary sinus blood. Twenty-seven patients of either sex (m/f = 21/6), undergoing coronary artery bypass grafting under extracorporeal circulation, were studied. Monitoring included a Swan-Ganz catheter and a coronary sinus line. The correct position of the late was verified by the waveform displayed in the monitor. Immediately after cannulae placement, a hemodynamic profile was obtained and simultaneous arterial and coronary sinus sampling for blood gas analysis was done in an ABL 720 (Radiometer Copenhagen) analyzer. A second collection of the same data was obtained five minutes later with the patients in a slight "head-down" position. Conditions for exclusion was intersample variation of hemoglobin's concentration greater than 15% and sodium ion concentration difference greater than 10% of the greater value. Arteriovenous oxygen partial pressure difference (deltaP(a-cs)O2), veno-arterial carbon dioxide partial pressure difference (deltaP(cs-a)CO2), O2 & CO2 content difference and heart's respiratory quotient were calculated and correlated to cardiac output (CO) and the other hemodynamic parameters. Statistical analysis employed t-paired test and linear regression. No ischemia was detected during sampling. "Head-down" position had a significant impact to all hemodynamic parameters except heart rate. In both data rows, although CO ranged widely and altered significantly, coronary sinus oxygen saturation and arteriovenous O2 content difference were stable and showed insignificant correlations to all the hemodynamic parameters that were studied. Carbon dioxide content difference (coronary sinus-arterial) showed a trending of decrease with higher flow. DeltaP(cs-a)CO2 appeared stable and independent of flow. Finally, respiratory quotient decreased significantly from 0.91 +/- 0.4 to 0.86 +/- 0.4 (mean +/- SD; p < 0.05). The heart's high basal oxygen consumption and the almost near hemoglobin's desaturation transcoronary extraction of oxygen limits the value of coronary sinus saturation monitoring as indicator of coronary flow. Heart's little extraction reserve is faced with coronary flow reserve. In the physiologic range and under the conditions of anesthesia, elevated CO2 production is accompanied with increased coronary flow. Under these circumstances, deltaP(cs-a)CO2 appears stable and is not suitable for clinical decisions concerning heart's coronary flow.

'On-line' alterations of contralateral jugular blood gas profile during carotid clamping.

The aim of this work was to record the metabolic status of the brain (pH, PCO(2) and PO(2)) during carotid endarterectomy (CEA), with the use of an intravascular multiparameter sensor (Paratrend 7) via retrograde catheterization of the contralateral jugular vein. Twenty-four patients with ASA grades II and III scheduled for CEA were included in the study. After induction of anesthesia, the contralateral internal jugular vein was punctured retrogradely and the sensor was introduced. During clamping, pH became persistently more acidotic (7.34-7.31; p < 0.05), PCO(2) was elevated (43.2-46.8 mm Hg; p < 0.05) while most of the patients showed a non-significant decrease in PjvO(2)/SjvO(2) (jv = jugular venous). Correlation with clamping time or stump pressure was not significant. Unclamping was followed by a short period (5- 9 min) of decrease in pH and elevation of PCO(2) (7.30-7.22; p < 0.05, and 48.0-52.5 mm Hg; p < 0.05, respectively). PjvO(2) was significantly elevated (51.8-58.0 mm Hg; p < 0.001) after the restoration of flow. The study suggests that local CO(2) creates conditions for compensation of flow after the application of a carotid clamp. We consider that this monitoring technique, after further validation, may provide useful information.

Incidence of abdominal wall hernias in patients undergoing aortic surgery for aneurysm or occlusive disease.

BACKGROUND: The aim of this study was to compare the incidence of abdominal and incisional hernias in patients with abdominal aortic aneurysm (AAA) versus patients with aortoiliac occlusive disease (AOD). PATIENTS AND METHODS: The study included retrospectively 121 patients, who underwent elective aortic surgery due to AAA (n = 63) or AOD (n = 58) in the period between January 1998 and January 2000. The patients were examined for the presence of abdominal hernias upon admission, as well as for the development of incisional hernias on follow-up. RESULTS: The incidence of inguinal hernias was significantly higher in the group AAA (21/6-33.3%) compared to the group with AOD (6/58-10.3%) (p < 0.01). The incidence of other abdominal wall hernias (umbilical, epigastric or miscellaneous hernias) was also significant higher in AAA group. Furthermore, the incidence of inguinal hernias was significantly higher in the subgroup of patients with an aneurysm diameter more than 6 cm (41.5% vs 18.2%, p < 0.05). The mean follow-up of the patients was 1.7 +/- 0.3 years. 7 cases of incisional hernia were noted in the AAA group (11.1%) and only 2 cases in the AOD group (3.4%) (p < 0.05). The size of the aneurysm had no influence on the incidence of incisional hernias in the AAA group. CONCLUSION: We conclude that there seems to be an increased incidence of abdominal wall hernias as well as postoperative incisional hernias in patients undergoing aortic surgery for aneurysm disease compared with aortoiliac occlusive disease.

Continuous monitoring of arterial blood gases and pH during laparoscopic cholecystectomy using a Paratrend sensor.

BACKGROUND: The safety of laparoscopic procedures has been studied broadly. The effects on cardiopulmonary function and reliable methods of monitoring concentrate more interest. METHODS: A prospective study in 22 consecutive patients with ASA I and II was designed. The continuous assessment of alterations of arterial blood gases, pH, arterial pressure and heart rate during laparoscopic cholecystectomy by carbon dioxide pneumoperitoneum American technique was achieved using an intra-vascular multi-parameter sensor Paratrend. RESULTS: Statistically significant increase of both PaCO2 and PE.CO2 in parallel and a corresponding decrease of pH were found in correlation with the duration of the pneumoperitoneum. The values of PaO2, Sat O2, base excess, H-CO3, mean arterial pressure and heart rate showed no statistically significant alterations at any time throughout the procedure. No differences were noted between younger patients and in the elderly or between patients with ASA I and II. CONCLUSIONS: Intra-arterial blood-gas sensor ensures continuous on-line monitoring, but no abnormal and threatening changes occur during laparoscopic cholecystectomy in otherwise healthy people.

Alterations in carbon dioxide release during abdominal aortic clamping for aneurysmal or occlusive repair.

BACKGROUND: Application and removal of an infrarenal aortic clamp is associated with changes in oxygen consumption, especially when collateral perfusion is limited. Carbon dioxide production during abdominal aortic clamping is expected also to change. The aim of this study was to evaluate the alterations of CO2 release during abdominal aortic surgery. DESIGN: prospective study. SETTING: University Hospital, Greece. PATIENTS: 17 patients undergoing abdominal aortic aneurismal (AAA) repair and 8 patients undergoing repair of aortoiliac occlusive disease. INTERVENTION: intraoperative record or calculation of PaCO2, PetCO2, PECO2, VD, VDalv, and VCO2. Patients with aneurysms were randomly divided to have constant ventilation (group AA) or modified ventilation to preserve normocapnia (group AB) during clamping. Ventilation was kept constant in the occlusive patients group (group OD). RESULTS: Patients with AAA showed a significant decrease of VCO2 during clamping and an elevation after unclamping in both groups (AA and AB), with no difference of statistical importance between them. During clamping, PetCO2/ PaCO2 ratio was decreased and VDalv was increased especially in group AA, while unclamping produced the opposite effect. Occlusive patients showed insignificant alterations. CONCLUSIONS: Our results suggest that, the calculated alveolar dead space is only an indicator of the true V/Q in patients with AAA, because it is strongly dependent on the CO2 load to the lungs, which is markedly altered in the same period. The modification of ventilation during clamping based only on PetCO2 and not on arterial sampling, could possibly lead to hypercarbia in these patients.

Continuous contralateral jugular acid-base and blood gas monitoring during carotid endarterectomy.

BACKGROUND: The aim of this study is to evaluate the intravascular multiparameter sensor Paratrend 7 (P7) for continuous acid-base and blood gas monitoring after retrograde jugular catheterization during carotid endarterectomy. PATIENTS AND METHODS: We studied 11 patients with history of smoking (72.7%), coronary artery disease (72.7%), hypertension (100%), diabetes mellitus (55.5%) and TIA's and/or nondisabling stroke (90.9%). The contralateral internal jugular vein was punctured retrogradely and the calibrated P7 sensor was introduced. The sensor was removed after surgery. The P7 provides continuous graphical display of pH, pCO2, and pO2, while temperature, oxygen saturation, HCO3 concentration and base excess are displayed numerically. RESULTS: Mean duration of carotid cross-clamping was 17.0 +/- 6.2 min. Mean stump pressure was 50.2 +/- 12.9 mmHg. Intraluminal shunting was not used in any operation. All sensors were easily inserted. During clamping, pH became persistently more acidic (7.31 to 7.28; p < 0.05), pCO2 was elevated (44.7 to 49.8 mmHg; p < 0.05) while, in the majority of the patients, there was a non significant decrease in pjvO2/SjvO2. Declamping was followed by a short period of decrease of pH and elevation of pCO2 reminiscent of wash out phenomena. PjvO2 was significantly elevated (53.8 +/- 5.2 to 59.0 +/- 5.8 mmHg; p < 0.001) after the restoration of flow. In one case, P7 was diagnostic for unsuccessful endarterectomy. CONCLUSIONS: P7 is useful during carotid endarterectomy providing continuous and "on-line" information on brain metabolism. It is a simple and powerful technique, which should be further investigated.

Continuous monitoring of arterial blood gases and pH during intraoperative rapid blood administration using a Paratrend sensor.

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the effects of rapid transfusion of packed red cells on the arterial blood gases and acid-base status of the recipient. MATERIALS AND METHODS: We studied 16 patients (mean age 66.3+/-9.9 years) who received rapid transfusion of 632.8+/-287.2 g of packed red cells in CPDA-1, stored before use for a period of 15.2+/-4.4 days. During transfusion, monitoring of pH, PCO2 and PO2 was continuous using an intra-arterial multiparameter sensor (Paratrend 7, Biomedical Sensors, UK). RESULTS: The rate of the transfusion was 73.1+/-9.6 g/min and the duration of observation was 35.8+/-12.8 min. Arterial pH decreased from 7.446+/-0.023 to 7.385+/-0.034 (p<0.001) and PCO2 increased from 32.31+/-1.35 to 36.41+/-1.86 mmHg (p<0.001). Delta pH and delta PCO2 showed significant correlation to the weight and the age of the transfused blood (p<0.001 for both dependent variables). The rate of pH change was positively but insignificantly correlated to the rate of the transfusion. Base excess was significantly decreased and end-tidal CO2 (PetCO2) was increased from 25.8+/-2.0 to 28.1+/-2.3 mmHg (p<0.05), significantly correlating to the amount and age of the administered component (p<0.05). PetCO2 was not elevated when PCO2 changes were minimal. Alterations in PO2 were not specific and our clinical impression was that they were related to unmeasured parameters. CONCLUSION: Our findings suggest that the fall in pH and the elevation in PCO2 which occur during rapid transfusion of packed red cells may go undetected or be misinterpreted if the acid-base status of the recipient is not monitored continuously. These alterations are mainly of metabolic character and depend on the amount and age of the transfused component. Our data suggest that arterial sampling is essential during massive transfusions.