Gary Hartstein

Comparison of functional residual capacity and static compliance of the respiratory system during a positive end-expiratory pressure (PEEP) ramp procedure in an experimental model of acute respiratory distress syndrome

IntroductionFunctional residual capacity (FRC) measurement is now available on new ventilators as an automated procedure. We compared FRC, static thoracopulmonary compliance (Crs) and PaO2 evolution in an experimental model of acute respiratory distress syndrome (ARDS) during a reversed, sequential ramp procedure of positive end-expiratory pressure (PEEP) changes to investigate the potential interest of combined FRC and Crs measurement in such a pathologic state.MethodsARDS was induced by oleic acid injection in six anesthetised pigs. FRC and Crs were measured, and arterial blood samples were taken after induction of ARDS during a sequential ramp change of PEEP from 20 cm H2O to 0 cm H2O by steps of 5 cm H2O.ResultsARDS was responsible for significant decreases in FRC, Crs and PaO2 values. During ARDS, 20 cm H2O of PEEP was associated with FRC values that increased from 6.2 ± 1.3 to 19.7 ± 2.9 ml/kg and a significant improvement in PaO2. The maximal value of Crs was reached at a PEEP of 15 cm H2O, and the maximal value of FRC at a PEEP of 20 cm H2O. From a PEEP value of 15 to 0 cm H2O, FRC and Crs decreased progressively.ConclusionOur results indicate that combined FRC and Crs measurements may help to identify the optimal level of PEEP. Indeed, by taking into account the value of both parameters during a sequential ramp change of PEEP from 20 cm H2O to 0 cm H2O by steps of 5 cm H2O, the end of overdistension may be identified by an increase in Crs and the start of derecruitment by an abrupt decrease in FRC.

A European, multicenter, observational study to assess the value of gastric-to-end tidal Pco(2) difference in predicting postoperative complications

Automated online tonometry displays a rapid, semi-continuous measurement of gastric-to-endtidal carbon dioxide (Pr-etCO2) as an index of gastrointestinal perfusion during surgery. Its use to predict postoperative outcome has not been studied in general surgery patients. We, therefore, studied ASA physical status III–IV patients operated on for elective surgery under general anesthesia and a planned duration of >2 h in a European, multicenter study. As each center was equipped with only 1 tonometric monitor, a randomization was performed if more than one patient was eligible the same day. Patients not monitored with tonometry were assessed only for follow-up. The main outcome measure was the assessment of postoperative functional recovery delay (FRD) on day 8. Among the 290 patients studied, 34% had FRD associated with a longer hospital stay. The most common FRDs were gastrointestinal (45%), infection (39%), and respiratory (35%). In those monitored with tonometry (n =179), maximum Pr-etCO2 proved to be the best predictor increasing the probability of FRD from 34% for all patients to 65% at a cut-off of 21 mm Hg (2.8kPa) (sensitivity 0.27, specificity 0.92, positive predictive value 64%, negative predictive value 70%). We conclude that intraoperative Pr-etCO2 measurement may be a useful prognostic index of postoperative morbidity.

Thromboprophylaxis in microsurgery

Abstract Microsurgical free tissue transfer has become a gold standard in a wide range of clinical situations. Thrombosis at the anastomotic site is not only the most common cause of failure of microsurgical operations, but it is also one of the factors resulting in microcirculatory intravascular thrombosis in free flaps. All conditions of thrombus formation, defined by Virchow in 1856, are encountered in free flap surgery. This literature review concerns the problem of thromboprophylaxis in microsurgery. All citations published this last ten years (1996–2005) concerning this problem are noted. Data are confronted with other specialties, particularly vascular surgery, or with large retrospective studies. Protocol used in our institution is presented at the end of this lecture.

A fatal case of Perthes syndrome

Perthes syndrome, or traumatic asphyxia, is a clinical syndrome associating cervicofacial cyanosis with cutaneous petechial haemorrhages and subconjonctival bleeding resulting from severe sudden compressive chest trauma. Deep inspiration and a Valsalva maneuver just prior to rapid and severe chest compression, are responsible for the development of this syndrome. Current treatment is symptomatic: urgent relief of chest compression and cardiopulmonary resuscitation if needed. Outcome may be satisfactory depending on the duration and severity of compression. Prolonged thoracic compression may sometimes lead to cerebral anoxia, irreversible neurologic damage and death. We report a fatal case of Perthes syndrome resulting from an industrial accident.

Air versus ground transport of patients with acute myocardial infarction: experience in a rural-based helicopter medical service.

Aims Primary prehospital Helicopter Emergency Medical Service (HEMS) interventions may play a role in timely reperfusion therapy for patients with ST-segment elevation myocardial infarction (STEMI). We designed a prospective study involving patients with acute myocardial infarction aimed at the evaluation of the potential benefit of such primary HEMS interventions as compared with classical Emergency Medical Services ground transport. Methods and results This prospective study was conducted from 1 July 2007 to 15 June 2012. Successive patients with STEMI eligible for percutaneous coronary intervention were included. Simulated ground-based access times were computed using a digital cartographic program, allowing the estimation of healthcare system delay from call to admission to the catheterization laboratory. During the study period, 4485 patients benefited from HEMS activations. Of these patients, 342 (8%) suffering from STEMI were transferred for primary percutaneous coronary intervention. The median primary response time was 11 min (interquartile range: 8–14 min) using the helicopter and 32 min (25–44 min) using road transport. The median transport time was 12 min (9–15 min) using HEMS and 50 min (36–56 min) by road. The median system delay using HEMS was 52 min (45–60 min), whereas this time was 110 min (95–126 min) by road. Finally, the system delay median gain was 60 min (47–72 min). Conclusion Using HEMS in a rural region allows STEMI patients to benefit from appropriate rescue care with delays similar to those seen in urban settings.

Interactive videoconferencing versus audio telephone calls for dispatcher-assisted cardiopulmonary resuscitation using the ALERT algorithm: a randomized trial.

Objectives The ALERT algorithm, a telephone cardiopulmonary resuscitation (CPR) protocol, has been shown to help bystanders initiate CPR. Mobile phone communications may play a role in emergency calls and improve dispatchers’ understanding of the rescuer’s situation. However, there is currently no validated protocol for videoconference-assisted CPR (v-CPR). We initiated this study to validate an original protocol of v-CPR and to evaluate the potential benefit in comparison with classical telephone-CPR (t-CPR). Materials and methods We developed an algorithm for v-CPR, adapted from the ALERT t-CPR protocol. A total of 180 students were recruited from secondary school and assigned randomly either to t-CPR or to v-CPR. A manikin was used to evaluate CPR performance. Results The mean chest compression rate was higher in the v-CPR group (v-CPR: 110±16 vs. t-CPR: 86±28; P<0.0001), whereas depth was comparable between both groups (v-CPR: 48±13 vs. t-CPR: 47±16 mm; P=0.64). Hand positioning was correct in 91.7% with v-CPR, but only 68% with t-CPR (P=0.001). There was almost no ‘hands-off’ period in the v-CPR group [v-CPR: 0 (0–0.4) vs. t-CPR: 7 (0–25.5) s; P<0.0001], but the median no-flow time was increased in the v-CPR group [v-CPR: 146 (128–173.5) vs. t-CPR: 122 (105–143.5) s, P<0.0001]. The overall score of CPR performance was improved in the v-CPR group (P<0.001). Conclusion The v-CPR protocol allows bystanders to reach compression rates and depths close to guidelines and to reduce ‘hands-off’ events during CPR.

Impact of 6 % hydroxyethyl starch (HES) 130/0.4 on the correlation between standard laboratory tests and thromboelastography (TEG®) after cardiopulmonary bypass

BACKGROUND Hydroxyethyl starches (HES) affect the results of thromboelastography (TEG®). We sought to determine whether using HES rather than crystalloids for cardiopulmonary bypass (CPB) prime and intraoperative fluid therapy changes the TEG cutoff values best identifying patients with a low platelet count or a low fibrinogen level after CPB. METHODS Data from 96 patients who had on-pump cardiac surgery, a TEG® (kaolin-heparinase) and standard investigations of blood clotting performed after separation from CPB and protamine administration were retrospectively reviewed. Patients were assigned to the HES or crystalloid group according to whether balanced 6% HES 130/0.4 or balanced crystalloids were used for intraoperative fluid therapy and pump prime. Mutlivariable linear regression models with computation of the standardized regression coefficients were used to identify independent associations between the four main TEG parameters (R time, alpha angle, K time and MA) and the type of fluid used, the INR, the aPTT, the fibrinogen level and the platelet count. Receiver-operating-characteristic curves were used to assess the effect of HES on the ability of TEG parameters to identify patients with a platelet count<80.000μl(-1) or a fibrinogen level<1.5 gr l(-1) and on the cutoff values best identifying these patients. RESULTS The type of fluid used significantly affected the MA (P<0.001), the K time (P<0.001) and the alpha angle (P<0.001) regardless of the results of the standard clotting tests. According to standardized ß regression coefficients the platelet count and the type of fluid used were stronger predictors of the MA, the alpha angle and the K time than the fibrinogen level. MA better predicted platelets<80.000μl(-1) than K time and alpha angle (P=0.023). The best cutoff value of MA identifying patients with platelets<80.000μl(-1) was 62mm in the crystalloid group and 53mm in the HES group. MA, K time and alpha angle were poor predictors of the postoperative fibrinogen level. CONCLUSION HES significantly changes the cutoff value of TEG® MA best identifying patients<80.000μl(-1) after on-pump cardiac surgery.