Induction of anesthesia can be accomplished with intravenous or inhalational anesthetic agents, which have both desired and side effects. The aim of this study was to record, investigate and compare the hemodynamic profile of five different induction anesthetic agents in patients undergoing major vascular surgery. One hundred and fifty patients, who were scheduled for major vascular surgery, were randomly assigned into five groups according to the anesthetic agent that was used for anesthesia induction. The five agents used for anesthesia induction were: propofol [2mg/kg], thiopental [3mg/kg], etomidate [0.3mg/kg], midazolam [0.2mg/kg] and diazepam [0.3mg/kg]. Before induction of anesthesia patients were administered Ringer lactate to replace volume deficit due to preoperative fasting. Besides standard intraoperative monitoring, an arterial catheter and a pulmonary artery catheter were placed in all patients before anesthesia induction. Continue reading
Central venous pressure (CVP) measurement along with invasive arterial pressure measurement are the two most widely used monitoring parameters in the Intensive Care Unit (ICU) and in the operating room (OR).In contrast with left heart catheterization, right heart catheterization is a procedure which is performed in the daily clinical practice both in the OR and the ICU and with which all anesthesiologists are well familiarized. Despite the limited usefulness of absolute CVP values, analysis of the CVP waveform offers important information regarding patient’s underlying pathology.ECG tracing should be taken concurrently with CVP measurement and CVP should be evaluated and interpreted in relationship to the ECG. CVP values are affected by several parameters such as mechanical ventilation and PEEP application, which should be taken into account when interpreting CVP measurements.
Tricuspid regurgitation (TR) is a relatively common abnormality and in most of the cases it is asymptomatic and has no clinical significance. In regard to etiology, TR can be categorized as primary (or organic) and secondary (or functional).TR allows blood to flow backwards across the valve from the right ventricle to the right atrium during right ventricle systole. When blood backflow is significant there may be giant systolic V waves in the CVP waveform. In case of severe TR, the giant systolic V waves are so prominent that the CVP waveform resembles the right ventricular pressure contour. This is called ventricularization of the right atrial pressure waveform. In contrast with the giant V waves in the CVP waveform, ventricularization of the right atrial pressure waveform is the most specific diagnostic criterion of severe TR. TR disease is diagnosed and thoroughly evaluated by echocardiography, which can give us information about its etiology and severity. However, CVP waveform may be indicative of TR and therefore could trigger further investigation and evaluation by echocardiography. Continue reading
Increased IAP often coexists with sepsis in severely ill patients in the ICU, under mechanical ventilation and pharmaceutical support of the circulation with inotropes and vasoactive drugs. Both conditions have an unfavorable effect on the cardiovascular system. The purpose of this experimental study was to record the effect of increased intra-abdominal pressure on the cardiovascular system of pigs, with or without additional sepsis. Sixteen male pigs were randomly assigned in two groups A and B. In both groups, after induction to anesthesia and mechanical ventilation, the intra-abdominal pressure was increased to 25mmHg by helium insufflation in the peritoneal cavity, and that level of IAP was preserved until the end of the experiment. In Group A no other intervention apart from the increase in IAP was made, whereas in Group B, 60 minutes after the increase in IAP, 100μg/kg LPS were administered. Data were recorded after induction of anesthesia and initiation of mechanical ventilation (baseline measurement/measurement 0) and thereafter every 20 min after intra-abdominal pressure increase. The last measurement (measurement 9) was obtained immediately before release of pneumoperitoneum. Parameters measured or calculated included HR, BP(s,d,m), RVPs, PAP(s,d,m), PΑWP, CO, SV, SVR, PVR, SvO2, ETCO2. HR increased statistically significantly only in Group B, 60 minutes after the administration of LPS. BP (s, d, m) presented a significant change only in Group B, an initial increase immediately after LPS administration, followed by a decrease. CVP, RVPs and PAP (s, d, m) increased in both groups after IAP increase, whereas they presented an additional increase in Group B, after LPS administration. PΑWP changed only in Group B, after LPS administration. CO and SV were dramatically reduced in Group B, immediately after LPS administration, but gradually recovered their initial values until the end of the experiment. SVR changed only in Group B. They increased after LPS administration and then they gradually decreased. PVR increased dramatically after LPS administration and, despite gradual decrease they remained at high values until the end of the experiment. SvO2 decreased in Group B after LPS administration but gradually recovered its initial values. At the conditions of this particular experiment, the increase in intra-abdominal pressure was well tolerated by the laboratory animals. On the contrary, sepsis induction by LPS administration had an unfavorable effect on the cardiovascular system. Continue reading
The deficiency of the natural heart pacemaker, the conduction disturbances and the appearance of arrhythmias are common complications after cardiac surgery. Placement of epicardiac electrodes (ventricular, atrial, or both) during cardiac surgery remains common practice, even though few patients will actually need some kind of temporary epicardiac pacing for various periods of time. Temporary epicardiac pacing may be ventricular, atrial or atrioventricular, depending on the specific features of each patient and it aims at preserving the cardiac rhythm, securing the desired heart rate and achieving an acceptable cardiac output. Temporary epicardiac pacing is not without danger, since, under specific circumstances, it may have a negative impact on the hemodynamics of the patient, to the point of circulatory collapse. It may also cause ventricular tachycardia (R on T phenomenon) and cardiac arrhythmias (if pacing is not synchronized to the heart’s natural pacemaker). Ventricular Pacing and Sensing (VVI) is accomplished by the placement of electrodes only on the ventricles, which a priori means a certain degree of hemodynamic compromise, due to the loss of atrial contribution in preserving cardiac output. In certain occasions, this impact may be even more significant. This case report concerns a patient who underwent Coronary Artery Bypass Grafting (CABG) and after placement of the electrodes of temporary epicardiac ventricular pacing he presented significant decrease in systemic arterial pressure and the appearance of cannon A waves on central venous pressure (CVP) tracing every time the pacemaker was triggered. These phenomena, which receded after the disconnection of the pacemaker, consists a case of Pacemaker Syndrome.This problem was solved by adjusting the pacemaker’s frequency at a rate lower than that of the patient’s natural pacemaker. Continue reading
Evaluation of monitoring readings, taking into account each patient’s pathology as well as the impact of every medical intervention can guide us to make optimal clinical decisions in the periopeative setting. We present three cases in which clinical decisions concerning the management of acute perioperative pulmonary hypertension were based both on haemodynamic monitoring readings and on each patient’s specific pathology. First case: After anesthesia induction in a patient with severe aortic valve insufficiency, an increase in pulmonary artery pressure was recorded. Infusion of isoprenaline, which has a positive chronotropic effect, decreased diastolic time, diastolic blood flow into the left ventricle and also pulmonary artery pressure. Second case: A patient with severe aortic valve stenosis was found with increased pulmonary artery pressure. Intravenous administration of atenolol (1+1mg) reduced the heart rate and the pulmonary artery pressure. Third case: A 15 year old patient with aortic isthmus rupture underwent open surgical repair with graft interposition. After establishment of one lung ventilation and left thoracotomy, pulmonary artery pressure increased. Pulmonary hypertension was managed successfully by oxygen insufflation to the non-ventilated left lung. In our first patient, heart rate increase reduced diastolic time, which decreased the amount of retrograde blood flow into the left ventricle through the regurgitant aortic valve. In the second patient, the heart rate reduction decreased blood flow velocity through the stenotic aortic valve as well as the pressure gradient between left ventricular chamber and aorta. In both patients, enhanced left ventricular function resulted in a reduction in pulmonary artery pressure. Decrease of the alveolar partial pressure of oxygen (PAO2) is the most important parameter that stimulates hypoxic pulmonary vasoconstriction. Oxygen insufflation increased PAO2, resulting in a decrease in pulmonary artery pressure .Clinical decisions based on haemodynamic monitoring readings resulted in effective management of pulmonary hypertension and in a good patient outcome. Continue reading
The interaction between increased Intra Abdominal Pressure (IAP) and Intrathoracic Pressure under different Positive End Expiratory Pressure (PEEP) levels is intriguing, since these two conditions coexist frequently in several clinical settings. The aim of our study was to investigate the interaction between different PEEP levels and increased IAP during laparoscopic cholecystectomy. In fifty two patients, who underwent scheduled laparoscopic cholecystectomy, cardiovascular parameters were determined by an Oesophageal Doppler Monitor device during two different time periods, before and after pneumoperitoneum, and under five conditions: (i) PEEP 0 cmH2O (ii) PEEP 5cm H2O (iii) PEEP 10cm H2O (iv) PEEP 15cm H2O and (v) in the absence of PEEP or ventilation. Cardiac output and stroke volume showed a statistically significant decrease compared to the baseline value after the application of different PEEP levels, when there was no pneumoperitoneum (p<0.05). However, both parameters increased, when PEEP and pneumoperitoneum were applied together (p<0.001). Corrected flow time, peak flow velocity in the descending thoracic aorta and mean acceleration showed similar alterations but not at all PEEP levels. Finally, αt the no PEEP or ventilation phase, the negative effects of increased IAP on the cardiocirculatory function were predominant. According to these results, application of PEEP seems to counterbalance the negative hemodynamic effects of increased IAP. Moreover, it could also be concluded that ‘ideal’ PEEP level might be the one that borders the IAP level, since the best cardiac output and stroke volume values were reported at that point. Continue reading
The occurrence of intraoperative oxygenation impairment is common even in healthy individuals and will vary depending on the patient and the type of surgery. The purpose of this study was to evaluate the incidence of oxygenation impairment in patients with normal lung function and to study the safety and efficacy of three different recruitment strategies. Out of a total number of 430 patients, 150 patients developed intraoperative oxygenation impairment, which was defined as the drop of PaO2/FiO2 ratio below 300. These 150 patients were randomly assigned into four study groups according to the recruitment strategy applied. Group A (N: 38): Application of three hyperinflations of the lungs at airway pressure 40cmH2O for 10 sec, followed by an increase in PEEP from 5 to 10cmH2O. Group B (N: 38): Increase in PEEP from 5 to 10cmH2O. Group C (N: 37): Application of three hyperinflations of the lungs at airway pressure 40cmH2O for 10 sec, without any PEEP alteration and Group D (N: 37): No maneuver. Measurements were taken at the phase of oxygenation deterioration and at 5, 15, 30, 45 and 60min after applying the maneuvers and also before extubation. From a total of 430 patients 150 developed oxygenation impairment (38.4%). The median onset time of the deterioration was 30min after intubation and mechanical ventilation. In group A the PaO2/FiO2 ratio increased significantly immediately after the maneuvers and remained elevated until extubation. In group B the PaO2/FiO2 ratio presented a gradual increase to significant levels before extubation. In group C, the instant post-maneuver increase of oxygenation was not sustained until extubation. Finally in group D a gradual decrease of the PaO2/FiO2 ratio was recorded until the end of surgery. According to the results of our study, one third of patients developed intraoperative oxygenation impairment approximately half an hour after intubation. The application of three hyperinflations of the lungs at an airway pressure of 40cmH2O for 10 sec, followed by an increase in PEEP from 5 to 10cmH2O proved to be the most effective treatment of impaired oxygenation. Continue reading
The aim of this study was to evaluate resuscitation skills and knowledge of the nursing staff of University Hospital “AHEPA”, who have previously successfully participated in a validated training CPR/AED course, held in ourhospital.In our study 60 professionally active nurses were involved. After completion of a predesigned questionnaire, they were expected to respond to a simulated cardiac arrest-CA scenario in an area where automated external defibrillation-AED was available. The questionnaire consisted of several questions regarding demographic data, participant’s personal opinion on the resuscitation training program, CPR performance and nurse’s attitudes when facing a CA. Participants were evaluated according to the European Resuscitation Council assessment form for basic life support-BLS with the use of AED (consisting of performance in 17 skills).The vast majority of the study population were female nurses (86.7% and 83.3% respectively), 41-50 years old (70%) with more than 21years working experience (53.3%). Continue reading
Factors affecting cardiac function in dialysis patients include arterial blood pressure, anemia, intra-vascular volume and the arteriovenous fistula (AVF). We investigated the acute and chronic effects of basilic vein transposition (mean upper arm brachial artery-basilic vein anastomosis) on both the cardiovascular system and the oxygen status.
Sixteen patients with end stage renal failure were enrolled in this study. Patients with heart failure, pericardial effusion or valvular heart disease were not included in the study. Echocardiography (preoperatively and six months after, stages 1 and 2 respectively) and a Swan-Ganz catheter (perioperatively) were used to assess the hemodynamic status during the phases of AVF construction. Flow measurements were made in the parts of the AVF system before, during and after the construction of the AVF.Moreover, at the same time phases blood sampling from the arterial line and the pulmonary artery catheter was performed, in order to assess oxygen and acidbase status. Continue reading
Apneic oxygenation is an adjunct "ventilation‟ technique that involves insufflation of oxygen at varying flows through a catheter that is inserted through the endotra-cheal tube and is positioned above the carina. Apneic oxygenation improves gas exchange efficiency and preserves the arterial oxygenation at an acceptable level. Continue reading