Improving blood product management in placenta accreta patients with severe bleeding: institutional experience

BACKGROUND

Placenta accrete spectrum (PAS) is a significant risk factor for postpartum hemorrhage and effective blood product management is critical in ensuring patient safety. In PAS patients undergoing cesarean section (CS) blood transfusion management guided by the combined clinical experience of the anesthesiologist and surgeon with point-of-care coagulation testing appears safe and effective. We describe and evaluate our experience and identify potential areas for improvement with blood product management in this patient population.

METHODS

A retrospective chart review of peri-operative demographic, anesthetic, and obstetric data was conducted for all patients with PAS undergoing CS between 2012 and 2018 at our center. To facilitate a practical evaluation of blood product management, we divided patients into two groups based on the severity of bleeding.

RESULTS

A total of 221 parturients with PAS underwent CS, with 133 in group 1 requiring excessive amounts of transfusion and 88 in group 2 requiring management similar to other uncomplicated CS cases. There were no deaths or instances of disseminated intravascular coagulation, and intensive care unit admission occurred in five cases (2.2%). Patients in group 1 had higher mean nadir values of intra-operative hemoglobin and platelet count. We observed a high rate of missing data for peri-operative measurement of lactate and fibrinogen, PAS grade documentation, and temperature monitoring.

CONCLUSION

Given no significant morbidity or mortality, clinical judgment in experienced centers appears safe for the management of PAS patients undergoing CS. The adoption of an institutional protocol and point-of-care coagulation testing could decrease over-transfusion and associated complications.

A novel point-of-care information system reduces anaesthesiologists' errors while managing case scenarios

BACKGROUND AND OBJECTIVES

The On-Line Electronic Help (OLEH) is a point-of-care information system for anaesthesia providers prepared by the European Society of Anaesthesiologists. In this preliminary study the effect of the OLEH availability on the incidence of knowledge-based errors during the management of case scenarios and participants' subjective evaluation of the OLEH were evaluated.

METHODS

After a short training session, 48 anaesthesiologists (24 junior residents, 12 senior residents and 12 board-certified) were presented randomly with six computer screen-based case scenarios with, and six without, the option of using the OLEH. Two reviewers evaluated the answers independently according to preconfigured guidelines.

RESULTS

The availability of the OLEH was associated with higher scores in 11 of the 12 scenarios, and with a decrease in the incidence of critical errors in 10 scenarios. Time to task completion was increased in one scenario only when the OLEH was used. The degree of professional experience was associated with better scores in five of the scenarios and with a reduced occurrence of critical errors in three scenarios. Forty-two out of 48 participants stated that finding information in the OLEH software was easy and that the system was helpful in managing the scenarios.

CONCLUSIONS

This preliminary study demonstrates the potential value of the OLEH in decreasing the number of knowledge-based errors made by anaesthesiologists. According to the encouraging results, the OLEH system is currently under evaluation using full-scale simulation scenarios in an operating room environment.

Predicting fluid responsiveness in patients undergoing cardiac surgery: functional haemodynamic parameters including the Respiratory Systolic Variation Test and static preload indicators

BACKGROUND

Prediction of the response of the left ventricular stroke volume to fluid administration remains an unsolved clinical problem. We compared the predictive performance of various haemodynamic parameters in the perioperative period in patients undergoing coronary artery bypass surgery. These parameters included static indicators of cardiac preload and functional parameters, derived from the arterial pressure waveform analysis. These included the systolic pressure variation (SPV) and its delta down component (dDown), pulse pressure variation (PPV), stroke volume variation (SVV), and a new parameter, termed the respiratory systolic variation test (RSVT), which is a measure of the slope of the lowest systolic pressure values during a standardized manoeuvre consisting of three successive incremental pressure-controlled breaths.

METHODS

Eighteen patients were included into this prospective observational study. Seventy volume loading steps (VLS), each consisting of 250 ml of colloid administration were performed before surgery and after the closure of the chest. The response to each VLS was considered as a positive (increase in stroke volume more than 15%) or non-response. Receiver operating characteristic curves were plotted for each parameter to evaluate its predictive value.

RESULTS

All functional parameters predicted fluid responsiveness better than the intrathoracic blood volume and the left ventricular end-diastolic area. Parameters with the best predictive ability were the RSVT and PPV.

CONCLUSIONS

Functional haemodynamic parameters are superior to static indicators of cardiac preload in predicting the response to fluid administration. The RSVT and PPV were the most accurate predictors of fluid responsiveness, although only the RSVT is independent of the settings of mechanical ventilation.

Pulse pressure and stroke volume variations during severe haemorrhage in ventilated dogs

BACKGROUND

Similarly to systolic pressure variation (SPV), pulse pressure variation (PPV) and stroke volume variation (SVV) derived from arterial pulse contour analysis have been shown to reflect fluid responsiveness in ventilated patients. However, unlike the SPV, both PPV and SVV have not been validated during extreme hypovolaemia. The aim of the present study was to examine whether these newly introduced variables respond to gradual hypovolaemia like the SPV by increasing gradually with each step of the haemorrhage even during extreme hypovolaemia.

METHODS

SPV, SVV and PPV were measured in 8 dogs following initial volume loading (10% of the estimated blood volume administered as colloid solution), 5 steps of graded haemorrhage, each consisting of 10% of the estimated blood volume, followed by retransfusion of the shed blood.

RESULTS

The correlations of the SVV, SPV and PPV to the stroke volume (SV) throughout the study were -0.89, -0.91 and -0.91, respectively. Correlations of the CVP and the global end-diastolic volume (GEDV) of the heart chambers to the SV were 0.79 and 0.95, respectively. The SPV correlated significantly with both the PPV and the SVV (r=0.97 and 0.93 respectively). However, the PPV increased by more than 400% at 50% haemorrhage compared with increases of 200% and 120% for the SVV and %SPV, respectively.

CONCLUSION

This study demonstrates that the present algorithm used for the calculation of the SVV and the formula used to calculate the PPV, perform well over a wide range of preload states including severe hypovolaemia. However, the PPV changes more than the SPV and SVV. This may be due to the changing relation of the SV to the pulse pressure when the filling of the aorta is greatly decreased.

Anaesthesiologists' views on the need for point-of-care information system in the operating room: a survey of the European Society of Anaesthesiologists

BACKGROUND AND OBJECTIVE

In this preliminary study we wanted to explore the attitudes of anaesthesiologists to a point-of-care information system in the operating room. The study was conducted as a preliminary step in the process of developing such a system by the European Society of Anaesthesiologists (ESA).

METHODS

A questionnaire was distributed to all 2240 attendees of the ESA's annual meeting in Gothenburg, Sweden, which took place in April 2001.

RESULTS

Of the 329 responders (response rate of 14.6%), 79% were qualified specialists with more than 10 yr of experience (68%), mostly from Western Europe. Most responders admitted to regularly experiencing lack of medical knowledge relating to real-time patient care at least once a month (74%) or at least once a week (46%), and 39% admitted to having made errors during anaesthesia due to lack of medical information that can be otherwise found in a handbook. The choice ofa less optimal but more familiar approach to patient management due to lack of knowledge was reported by 37%. Eighty-eight percent of responders believe that having a point-of-care information system for the anaesthesiologists in the operating room is either important or very important.

CONCLUSIONS

This preliminary survey demonstrates that lack of knowledge of anaesthesiologists may be a significant source of medical errors in the operating room, and suggests that a point-of-care information system for the anaesthesiologist may be of value.

Effect of a single dose of esmolol on the bispectral index scale (BIS) during propofol/fentanyl anaesthesia

BACKGROUND

Esmolol, a short-acting beta 1-antagonist, can reduce anaesthetic requirements and decrease seizure activity during electroconvulsive therapy even after a single dose of 80 mg. We studied the effect of esmolol on the bispectral index scale (BIS), which is a processed EEG recently introduced to monitor depth of anaesthesia.

METHODS

We gave esmolol 80 mg to 30 healthy male patients after induction of anaesthesia using propofol, with either fentanyl (group 1) or placebo (group 2). Patients were ventilated mechanically through a laryngeal mask airway and anaesthesia was maintained using propofol to keep the BIS value between 55 and 60.

RESULTS

Esmolol did not affect the BIS index value in either group. In group 1, the areas (mean (SD)) under the BIS vs time curve 3 min before and 3 min after esmolol administration were 145 (9) and 146 (8) respectively (P = 0.116). In group 2 values were 147 (8) and 146 (7) respectively (P = 0.344). In contrast, in group 1 the area under the systolic arterial pressure (SAP) curve was 299 (31) before and 270 (29) after esmolol (P < 0.001), and 156 (17) and 141 (17) respectively for heart rate (P < 0.001). In group 2 values were 326 (36) and 302 (41) for SAP (P < 0.001) and 182 (25) and 155 (22) for heart rate (P < 0.001).

CONCLUSIONS

The results suggest that a single dose of esmolol affects the SAP and heart rate but does not affect BIS values.

Cardiac output assessed by arterial thermodilution during exsanguination and fluid resuscitation: experimental validation against a reference technique

BACKGROUND AND OBJECTIVE

The arterial thermodilution technique offers the ability to measure cardiac output using only central venous and arterial catheters. However, the technique has been reported to overestimate cardiac output because of a higher loss of cold indicator due to the increased distance between the sites of injection and measurement. In this study, the two techniques were compared with respect to conditions of low cardiac output in which a longer passage time may further increase loss of indicator.

METHODS

Seventeen anaesthetized dogs were studied during hypovolaemic shock and fluid resuscitation. Cardiac output measurements were carried out simultaneously by arterial and pulmonary artery thermodilution techniques.

RESULTS

One-hundred-and-two measurements were performed. The mean cardiac output was 2.28 +/- 1.4Lmin(-1) by the pulmonary arterial technique and 2.29 +/- 1.56Lmin(-1) by the arterial thermodilution technique. The correlation coefficient between the two measurements was 0.95, the precision -0.04 +/- 0.41 Lmin(-1) and the limits of agreement from -0.86 to 0.78Lmin(-1). The agreement was also consistent at low cardiac outputs.

CONCLUSIONS

The arterial thermodilution technique may serve as a less invasive cardiac output monitor in conditions of severe bleeding and shock.

Pressure versus volume-controlled ventilation with a laryngeal mask airway in paediatric patients

BACKGROUND

The utility of positive pressure ventilation with the laryngeal mask airway (LMA) in children was described previously, but the possibility of gastric insufflation, related to high peak airway pressure, continues to be a disadvantage. In this prospective study, inspiratory pressures, air leak and signs of gastric insufflation were compared between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) using an LMA.

METHODS

Thirty-two ASA I patients, aged 4.5 +/- 4 years, who were scheduled for elective procedures under combined general anaesthesia and caudal analgesia, were enrolled. After inhalation induction and LMA insertion, each patient was randomly assigned to receive successively PCV and VCV. Peak pressures (PCV) and tidal volumes (VCV) were changed in order to achieve adequate ventilation [endtidal CO2 5-5.4 kPa (38-42 mmHg)].

RESULTS

Peak airway pressures were significantly lower with PCV than VCV (14.1 +/- 1.6 cmH2O versus 16.7 +/- 2.3 cmH2O, P < 0.001). No patient ventilated with PCV required peak pressure higher than 20 cmH2O compared with six patients ventilated with VCV (P < 0.05). Haemodynamic parameters, expiratory tidal volume and percent of leak were similar in both ventilatory modes and no signs of gastric insufflation were detected.

CONCLUSIONS

During general anaesthesia in children using an LMA, PCV offers lower peak inspiratory airway pressures while maintaining equal ventilation compared with VCV. Although no signs of gastric insufflation were detected in both groups, the lower pressures might be significant in patients with reduced chest wall or lung compliance.

Malignant hyperinflation of the nondependent lung during chest surgery

Unilateral malignant hyperinflation of the lungs during positive pressure mechanical ventilation was described during aggressive respiratory therapy of unilateral lung disease or in situations of significant difference in compliance between the two lungs. We report a case of malignant hyperinflation of the nondependent lung during chest surgery. The differential diagnosis and treatment with differential lung ventilation are described.

Monitored anesthesia care using remifentanil and propofol for awake craniotomy

Adequate analgesia and sedation with adequate respiratory and hemodynamic control are needed during brain surgery in awake patients. In this study, a protocol using clonidine premedication, intraoperative propofol, remifentanil, and labetalol was evaluated prospectively in 25 patients (aged 50 +/- 16). In all but one patient, no significant problems regarding cooperation, brain swelling, or loss of control were noticed, and it was not necessary to prematurely discontinue any of the procedures. One patient, who was uncooperative and hypertensive, became apneic with increasing sedation, and needed a laryngeal mask airway inserted. Patients were hemodynamically stable; elevated systolic blood pressure (>or= 150 mm Hg) was measured infrequently, and there were no events of significant hypotension, tachycardia, or bradycardia. Events of hypoxemia (SAO2 <or= 95%), severe hypoxemia (SaO2 <or= 90%), or hypoventilation (respiratory rate <or=8 minute), were frequent in the first ten patients, but the incidence decreased significantly in subsequent patients (P < .001). Three patients developed a focal neurologic deficit, and two patients experienced intraoperative seizures. Nausea and vomiting were not recorded in any of the patients. Although these findings attest to the safety of awake craniotomy, they demonstrate the difficulty of achieving adequate sedation without compromising ventilation and oxygenation. The learning curve of using a new protocol and a new potent anesthetic drug is emphasized.

Propofol/remifentanil versus propofol alone for bone marrow aspiration in paediatric haemato-oncological patients

BACKGROUND

This prospective randomized study was designed to evaluate the effects of adding remifentanil to the standard propofol-based technique in the setting of paediatric haematology-oncology outpatient clinic.

METHODS

Eighty ASA III paediatric patients treated in the outpatient haematology-oncology clinic requiring bone marrow aspiration were randomly assigned either to the propofol (P) or the propofol/remifentanil (PR) group. The quality of anaesthesia and recovery were evaluated.

RESULTS

The total amount of propofol required to prevent patient movement was lower in the PR group. The time interval to eye opening and to home readiness was significantly lower in the PR group. Adverse respiratory events (RR < 10.min-1 or SpO2 < 90%) occurred significantly more in the propofol/remifentanil group.

CONCLUSIONS

The addition of remifentanil improved the conditions during the procedure and reduced the total amount of propofol, as well as the time to home readiness. However, the addition of remifentanil is associated with an increased risk of respiratory depression.

Stroke volume variation as a predictor of fluid responsiveness in patients undergoing brain surgery

Changes in arterial blood pressure induced by mechanical ventilation allow assessment of cardiac preload. In this study, stroke volume variation (SVV), which is the percentage change between the maximal and minimal stroke volumes (SV) divided by the average of the minimum and maximum over a floating period of 30 s, continuously displayed by the PiCCO continuous cardiac output monitor, was evaluated as a predictor of fluid responsiveness. Fifteen patients undergoing brain surgery were included. During surgery, graded volume loading was performed with each volume loading step (VLS) consisting of 100 mL of 6% hydroxyethylstarch given for 2 min. Successive responsive VLSs were performed (increase in SV > 5% after a VLS) until a change in SV of < 5 % was reached (nonresponsive). A total of 140 VLSs were performed. Responsive and nonresponsive VLSs differed in their pre-VLS values of systolic blood pressure, SV, and SVV, but not in the values of heart rate and central venous pressure. By using receiver operating characteristic analysis, the area under the curve for SVV (0.870, 95% confidence interval [CI]: 0.809 to 0.903) was statistically more than those for central venous pressure (0.493, 95% CI: 0.397 to 0.590, P = 7 x 10(-10)), heart rate (0.593, 95% CI: 0.443 to 0.635, P = 5.7 x 10(-10)), and systolic blood pressure (0.729, 95% CI: 0.645 to 0.813, P: = 4.3 x 10(-3)). An SVV value of 9.5% or more, will predict an increase in the SV of at least 5% in response to a 100-mL volume load, with a sensitivity of 79% and a specificity of 93%.

IMPLICATIONS

Stroke volume variation may be used as a continuous preload variable and in combination with the continuously measured cardiac output, defining on-line the most important characteristics of cardiac function, allowing for optimal fluid management.

Anesthesia for magnetic resonance guided neurosurgery: initial experience with a new open magnetic resonance imaging system

The authors present their initial experience with a compact open magnetic resonance (MR) image-guided system, (PoleStar N-10, Odin Medical Technologies, Yokneam, Israel) used in a standard operating room, modified for radio frequency (RF) shielding. The low intensity of the magnetic field (0.12T), and the ability to lower the magnet from the operative field during surgery allows for an almost routine surgical procedure, in addition to the benefits of using intraoperative MR imaging. Although an MR compatible anesthesia machine and monitoring system are used, the system offers anesthesiologists access to the patient at all times during the procedure, and the ability to use conventional surgical equipment, syringe pumps, and warming devices. Propofol and remifentanil, used for maintaining anesthesia, allow early extubation and neurological evaluation at the end of surgery. Electrocorticographic monitoring can be used during surgery for epilepsy, and awake craniotomy can be performed. More experience with this new imaging system is required to assess its influence on clinical decision making and outcome.

Novel, compact, intraoperative magnetic resonance imaging-guided system for conventional neurosurgical operating rooms

OBJECTIVE

Preliminary clinical experience with a novel, compact, intraoperative magnetic resonance imaging (MRI)-guided system that can be used in an ordinary operating room is presented.

DESCRIPTION OF INSTRUMENTATION

The system features an MRI scanner integrated with an optical and MRI tracking system. Scanning and navigation, which are operated by the surgeon, are controlled by an in-room computer workstation with a liquid crystal display screen. The scanner includes a 0.12-T permanent magnet with a 25-cm vertical gap, accommodating the patient's head. The field of view is 11 x 16 cm, encompassing the surgical area of interest. The magnet is mounted on a transportable gantry that can be positioned under the surgical table when not in use for scanning, thus rendering the surgical environment unmodified and allowing the use of standard instruments. The features of the integrated navigation system allow flap planning and intraoperative tracking based on updated images acquired during surgery.

OPERATIVE TECHNIQUE

Twenty patients with brain tumors were surgically treated using craniotomy or trans-sphenoidal approaches. One patient underwent conscious craniotomy with cortical mapping, and two underwent electrocorticography.

EXPERIENCE AND RESULTS

Planning was accurate. Resection control images were obtained for all patients during surgery, with precise localization of residual tumor tissue. There were no surgical complications related to the use of the system.

CONCLUSION

This intraoperative MRI system can function in a normal operating room modified only to eliminate radiofrequency interference. The operative environment is normal, and standard instruments can be used. The scanning and navigation capabilities of the system eliminate the inaccuracies that may result from brain shift. This novel type of intraoperative MRI system represents another step toward the introduction of the modality as a standard method in neurosurgery.

The pharmacokinetics of morphine and lidocaine in nine severe trauma patients

STUDY OBJECTIVE

To study the pharmacokinetic parameters of morphine and lidocaine after a single intravenous (i.v.) bolus in severe trauma patients.

DESIGN

Clinical case study.

SETTING

Department of Anesthesiology and Intensive Care of a university hospital.

PATIENTS

Nine patients, ages 24 to 91 years (mean 54.4 yrs), admitted to the hospital with severe trauma (Injury Severity Score > 20) were included in the study.

INTERVENTIONS

After initial evaluation and stabilization, a single i.v. dose of morphine 0.025 mg/kg and lidocaine 1.5 mg/kg was given separately, and blood samples were drawn for each drug serum concentration.

MEASUREMENTS AND MAIN RESULTS

Morphine pharmacokinetics was studied in eight patients, lidocaine pharmacokinetics in seven patients, and both drugs were studied in six patients. Morphine clearance 2.5 to 10 ml/kg/min (6 +/- 2.6, mean +/- SD) and volume of distribution 0.28 to 3.30 L/kg (1.4 +/- 1.0) were found to be lower than values described previously for healthy volunteers (33.5 +/- 9 ml/kg/min and 5.16 +/- 1.40 L/kg, respectively), and are similar to those described in trauma patients (5 +/- 2.9 ml/kg/min and 0.9 +/- 0.2 L/kg, respectively). In contrast, lidocaine clearance 4.5 to 9.4 ml/kg/min (6.7 +/- 1.7) and volume of distribution 0.39 to 1.20 L/kg (0.72 +/- 0.28) were similar to the value described in healthy volunteers (10 ml/kg/min and 1.32 L/kg, respectively).

CONCLUSION

Changes in pharmacokinetics of drugs eliminated by the liver may occur in patients with severe trauma. The preserved lidocaine clearance indicates an almost normal hepatic blood flow and suggests that other mechanisms may be involved in the lower morphine clearance. The findings may have applications for the treatment of severe trauma patients and suggest that drug monitoring might be needed in some instances so as to avoid toxicity.

Continuous psoas compartment block for anesthesia and perioperative analgesia in patients with hip fractures

BACKGROUND AND OBJECTIVES

The perioperative use of continuous psoas compartment block (CPCB) was compared with traditional pain management for patients with fracture of the femur. The anatomy of CPCB was also tested in cadavers.

METHODS

Forty consecutive patients (range, 67-96 years old) were prospectively randomized either to group A (given local anesthetics using a CPCB) or group B (given perioperative analgesia with meperidine). In another part of the study, CPCB was performed in 15 fresh cadavers, and dissection of the lumbar region was performed after dye injection.

RESULTS

Continuous psoas compartment block was performed successfully in all patients in group A and was used in the pre- (16-48 hours) and postoperative (72 hours) periods. Visual analog scale score in group A was lower than in group B in 5/7 preoperative and 9/9 postoperative 8 hourly assessments. Differences reached statistical significance (P < .05) in 3 and 5 of the assessments, respectively. Patient satisfaction was higher in group A in the pre- (P < .05) and postoperative periods (P<.03). The block failed to achieve surgical anesthesia in 85% (17/20) of the patients, and additional anesthesia was needed. The anatomic study failed to support the existence of a defined "psoas compartment" previously described, and supported the clinical findings. Injected dye was found in the region of the origin of the sciatic nerve (essential for the production of anesthesia for hip surgery) in only 26% (4/15) of cadavers.

CONCLUSIONS

The CPCB seems to be an appropriate technique for efficient and safe perioperative pain control. However, in our dissections, the psoas compartment was not well defined in all patients, thus, using this route for anesthesia may result in only partial success.

The effect of a chemical protective ensemble on intravenous line insertion by emergency medical technicians

Protective gear is mandatory for medical personnel treating casualties in a contaminated environment. In the present study, we assessed the ability of emergency medical technicians to insert an intravenous line in this situation. Sixty emergency medical technicians were randomized to a control group, wearing fatigues, and a study group, wearing full protective gear. The ability to insert an intravenous line in healthy volunteers was assessed 1, 2, 4, and 8 hours after randomization. We found no effect of protective gear (p = 0.543) or time in protective gear (p = 0.8869) on success rate or on time needed for successful task completion (p = 0.4005 and p = 0.9021, respectively). The overall success rate was 58.6%, 65% in the unprotected state and 56% in the protected state, and the time was 303 +/- 115 and 351 +/- 113 seconds, respectively. These findings suggest that introduction of an intravenous line is possible but time consuming even after a prolonged stay in full protective gear. Alternative methods for antidotal treatment, such as the use of automatic autoinjectors for intramuscular administration, might be suggested.

Elevated plasma atrial natriuretic peptide levels after occlusion of the thoracic aorta

STUDY OBJECTIVE

The influence of occlusion of the thoracic aorta by an intraluminal balloon on plasma atrial natriuretic peptide (ANP) levels was evaluated in humans.

METHODS

The changes in plasma ANP and plasma norepinephrine levels, and hemodynamic parameters were measured in 10 patients under general anesthesia undergoing regional chemotherapy treatment involving the 15-min inflation and subsequent deflation of an intraaortic balloon.

RESULTS

The hemodynamic changes observed were similar to those seen during aortic clamping and declamping in patients undergoing vascular surgery. Plasma ANP levels (median+/-SD) measured 1 min after inflation (146+/-117 pg/mL) and 1 min after deflation (168+/-189 pg/mL) of the aortic balloon were significantly higher than baseline values (83+/-55 pg/mL), with a mean increase, respectively, of 92% and 97% (95% confidence intervals [CI], 50 to 147% and 53 to 152%). Plasma ANP levels were still elevated 30 min after deflation (121+/-94 pg/mL), a 56% increase (95% CI, 21 to 100%), although the hemodynamic parameters had already returned to their baseline levels. There was no evidence that the hemodynamic variables were associated with changes in plasma ANP levels (all p values > 0.30). In addition, there was no evidence of an association between plasma ANP and plasma norepinephrine levels at any of the four individual sampling points (p > 0.17). Thirty minutes after deflation, however, norepinephrine levels were higher than baseline values.

CONCLUSIONS

The changes in plasma ANP levels after aortic occlusion and reinstitution of blood flow may be dependent on parameters other than atrial stretch and pressure.

The pharmacokinetics of morphine and lidocaine in critically ill patients

OBJECTIVE

To evaluate the pharmacokinetic parameters of morphine and lidocaine after a single intravenous dose in critically ill patients.

DESIGN

Prospective, clinical study.

SETTING

General intensive care unit (ICU) in a university hospital.

PATIENTS

Patients admitted to the ICU with severe systemic inflammatory response syndrome of various etiologies.

INTERVENTIONS

A single intravenous dose of morphine (0.025 mg/kg) and lidocaine (1.5 mg/kg) were given separately 12-36 h after admission, and arterial blood samples for serum drug levels were taken.

MEASUREMENTS AND RESULTS

Morphine pharmacokinetics were studied in 30 patients. The clearance (Cl) was found to be 5.7+/-2.3 ml/kg per min, volume of distribution of the central compartment (Vc) 0.16+/-0.12 l/kg and volume of distribution at steady state (Vss) 1.08+/-0.69 l/kg. These values are lower then those described previously for healthy volunteers (33.5+/-9 ml/kg per min, 1.01+/-0.31 l/kg, and 5.16+/-1.4 l/kg, respectively), and similar to those described in trauma and burned patients. Lidocaine pharmacokinetics were tested in 24 subjects. The Cl was 6.9+/-3.8 ml/kg per min, Vc 0.25+/-0.1 l/kg and Vss 0.78+/-0.26 l/kg. These values are not different from parameters published previously for healthy volunteers (10 ml/kg per min, 0.53 l/min and 1.32 l/min, respectively). No correlation was found between clinical variables and pharmacokinetic parameters of both drugs (ANOVA).

CONCLUSIONS

Both morphine and lidocaine have a reduced volume of distribution in critically ill patients. The normal lidocaine clearance indicates preserved hepatic blood flow and suggests that other mechanisms are involved in the reduced morphine clearance. These findings may have application for the treatment of ICU patients.

Hemodynamic changes during a new procedure for regional chemotherapy involving occlusion of the thoracic aorta and inferior vena cava

STUDY OBJECTIVE

To describe the hemodynamic consequences of a regional chemotherapy procedure involving occlusion of the thoracic aorta and inferior vena cava (IVC) by intraluminal balloons.

DESIGN

Prospective study.

SETTING

Operating rooms of an academic hospital.

PATIENTS

10 patients with inoperable intraabdominal malignancy.

INTERVENTIONS

After the induction of general anesthesia and the insertion of a pulmonary artery catheter the patients underwent the regional chemotherapy procedure.

MEASUREMENTS AND MAIN RESULTS

Occlusion of the thoracic aorta induced an increase in blood pressure (BP) and systemic vascular resistance (SVR) (41% +/- 8% and 80% +/- 15% from baseline, respectively), and a 30% +/- 7% decrease in cardiac output (CO). After aortic balloon deflation at the end of the procedure, we observed a decrease in BP to baseline values, decrease in SVR (to 62% +/- 12% below baseline), and increase in CO (to 80% +/- 15% above baseline). Those changes resemble those described during vascular surgery. Isolated occlusion of the IVC before aortic occlusion caused hemodynamic deterioration in only three of 10 patients, suggesting incomplete obstruction or collateral blood flow in others. Occluding the IVC while the aorta was occluded, caused minimal hemodynamic changes.

CONCLUSIONS

Independent inflation of the IVC balloon should not be performed routinely because of possible unpredicted hemodynamic instability. Inferior vena cava occlusion should always be performed after complete aortic occlusion, because it is then that it produces negligible hemodynamic consequences. It is possible that a better assessment of IVC occlusion after balloon inflation needs to be done by contrast injection to prevent a possible leak of chemotherapeutic drugs.

Survival after left ventricular rupture following blunt chest injury

Blunt traumatic rupture of the left ventricle of the heart is rarely diagnosed preoperatively and is usually fatal, with only a few survivors reported in the literature. This report describes a case of a 54-year-old woman who survived a left ventricular rupture from a motor vehicle accident. Her cardiac injury was not suspected because she was not hypotensive and had no signs of pericardial tamponade. She developed circulatory arrest 2 hours after her injury, during induction of anesthesia.

The effects of continuous operation in a chemical protective ensemble on the performance of medical tasks in trauma management

Treating casualties in a chemically hazardous environment constitutes a unique problem. Physical protection of the medical personnel may impair their performance and potentially affect patients' prognoses. The present study examined the effect of prolonged physical protection on the accomplishment of medical tasks related to trauma management. Sixty one emergency medical technicians, acclimatized to operating in protective gear, underwent four rounds of testing during eight hours of continuously wearing either a chemical protective suit or regular fatigues. The quality of the designated medical tasks, including sterility, was maintained throughout the study. A significant reduction in speed of performance was noted (approximately 30% slowing, p < 0.0001 in multivariate analysis) because of protective clothing. There was no additional decrement in performance following a prolonged stay in the protective gear. We conclude that in a chemically contaminated area, fully protected medical personnel are capable of treating trauma patients reasonably well, and for a relatively long period of time. The importance of pretraining and proper instruction is emphasized.

Outline of hospital organization for a chemical warfare attack

A plan for hospital organization in the event of chemical warfare is described. The basic principles are: a) isolation of the hospital receiving the casualties, b) several levels of triage, and c) treatment according to simple therapeutic protocols using appropriate treatment sites. Triage is based upon walking feasibility, respiratory status, age, and additional conventional injuries. The nurse's diagnostic and treatment authority is extended. Auxiliary staff (numbering hundreds of people) are needed for decontamination, stretcher bearing, artificial ventilation, etc. A nation-wide educational program on the prevention, decontamination and treatment of chemical warfare casualties is conducted in Israeli hospitals and drills are exercised frequently. This scheme is suitable for nerve gas poisoning, but can be easily modified for other chemical agents.

Survey of symptoms following intake of pyridostigmine during the Persian Gulf war

Pyridostigmine bromide, a reversible inhibitor of acetylcholinesterase (AChE), is effectively used as a pre-treatment to organophosphate intoxication. Previous studies have shown that an oral dose of 30 mg twice a day produces a sufficient inhibition of the enzyme activity (20-40%) without causing any significant adverse effect. During the Persian Gulf war pyridostigmine was taken for the first time under a chemical warfare threat. We searched for symptoms and complaints that may be related to the medication. Our survey included 213 soldiers who completed a questionnaire regarding possible symptoms and their severity. AChE inhibition level was compared between groups of soldiers with and without complaints. The most frequent symptoms were nonspecific and included dry mouth, general malaise, fatigue and weakness. Typical effects, such as nausea, abdominal pain, frequent urination and rhinorrhea, were infrequent. The severity of the symptoms was generally mild. The symptoms appeared around 1.6 h after taking the medication and recurred after each intake. No correlation was found between levels of cholinesterase and type or severity of complaints. Anxiety, which accompanies wartime, may have contributed to the appearance of significant symptoms. Further investigations concerning the effects of pyridostigmine ingestion under stressful conditions are warranted.

Combined chemical and conventional injuries--pathophysiological, diagnostic and therapeutic aspects

Chemical warfare (CW) agents may cause both conventional and chemical injuries. The effects of the two types of injuries may be reciprocal, leading to difficulties in assessing and treating such patients. Several aspects of the combined injury are discussed: increased exposure to CW agents following conventional trauma, owing to skin laceration or inability to use a gas mask (head, face or chest trauma); pathophysiological interactions between the two types of injuries; protection of medical personnel against CW intoxication; treatment limitations of personnel caused by their CW protection gear, when treating patients requiring urgent decontamination; and the influence of conventional trauma on the management of CW casualties. The Israel Defense Forces' recommendations for the treatment of combined injuries in a contaminated area include: a) airway maintenance, b) securing breathing and ventilation, c) circulation and hemorrhage control, d) antidote administration, e) decontamination with fuller's earth, f) dressing the wound, and g) evacuation to a noncontaminated area.

Physiological assessment of the passive children's hood

The physiological effect of the "passive children's hood" (PCH) was studied in 24 children: 8 toddlers (3-4.5 years old), 8 pre-school pupils (4.5-6 years) and 8 first- and second-grade pupils (6-8 years). This device consists of a children's gas mask and a transparent PVC (polyvinyl chloride plastic) covering (hood). Inspiratory CO2 and O2 (FiCO2 and FiO2, respectively), temperature and humidity were monitored at 10-min intervals while the children were occupied with sedentary activities (playing and watching TV) in a sealed room. Ambient temperature and relative humidity were approximately 27 degrees C and 75% respectively. In the PCH space the temperature was 2 degrees C higher and humidity was near saturation at the end of exposure. FiCO2 in 12 children exceeded 2%, which is the upper acceptable limit according to industrial standards. In four of them FiCO2 was greater than 4% and FiO2 less than 16%. Twenty-two children tolerated the PCH for 92 +/- 35 min (range 24-133 min) with no physiological complications. A significant correlation was found between childrens' age and tolerance time (r = 0.47, P less than 0.025). We conclude that children whose masks are not well adjusted may be exposed to rebreathing CO2-enriched air.

Severe reversible interstitial pneumonitis induced by low dose methotrexate: report of a case and review of the literature

A patient treated with 7.5 mg methotrexate/week (MTX) for rheumatoid arthritis (total dose 300 mg) developed high fever, dry cough and progressive dyspnea and hypoxemia due to a severe interstitial pneumonitis. MTX was discontinued and an infectious etiology was ruled out by cultures, serology and lung biopsy. Corticosteroids administered intravenously in high dose led to a dramatic improvement and a complete amelioration of all symptoms and signs. Pulmonary toxicity is a rare adverse effect of low dose MTX therapy and a review of the literature reveals 6 additional cases. Since MTX induced pneumonitis is a potentially fatal, yet completely reversible, disease, attention should be paid to even mild early respiratory symptoms in patients treated with low dose MTX and patient monitoring should include pulmonary function tests.

Interferon modulates the leukotriene C4-induced non-adherence properties of leukocytes: acquisition of an asthmatic phenotype

We have previously shown that peripheral blood leukocytes (PBL) of asthmatic patients acquire non-adherence properties after challenge with leukotriene C4 (LTC4), whereas PBL of normal individuals do not. Hence the use of the LTC4-induced leukocyte-adherence-inhibition (LAI) assay enables one to recognise an asthmatic phenotype on the basis of the ability of PBL to respond in vitro to LTC4. To examine the possibility that alpha interferon (IFN alpha) may have relevance to the pathogenesis of bronchial asthma, various concentrations of IFN were incubated with normal PBL and the acquisition of non-adhering properties was measured. We found that following 24 h incubation with 500 U/ml IFN, normal PBL were induced to respond to a standard dose of LTC4, and this reaction was abrogated by FPL 55712 and cyclohexamide.