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Signa Vitae

A Journal In Intensive Care And Emergency Medicine

Month: May 2017 (Page 1 of 2)

Pulmonary reperfusion injury

Abstract

Pulmonary reperfusion injury is a clinical syndrome with no single and recognized pathophysiologic mechanism. It is a major cause of morbidity and mortality following lung transplantation, cardiogenic shock, or cardiopulmonary bypass. The underlying mechanisms remain uncertain. Lung inflammatory injury induced by lipopolysaccharide, characterized by rapid sequestration of neutrophils in response to inflammatory chemokines and cytokines released in the lungs is an acceptable theory. Structural or functional impairment of surfactant has been noted in pulmonary reperfusion injury. The pathological changes may include bilateral pulmonary infiltrates, reduced lung compliance and worsening of gas exchange in the immediate posttransplant period. Recruitment maneuver and high positive end-expiratory pressure can relieve postoperative respiratory failure, especially in the patient with reperfusion pulmonary edema after pulmonary thromboendarterectomy. Pharmaceutical agents, including inhaled nitric oxide, soluble complement receptor type 1, prostaglandin E1 and exogenous surfactant, attenuate pulmonary reperfusion injury through distinct mechanisms. Extracorporeal membrane oxygenation and Novalung are temporary assistance in bridging to lung transplantation, stabilization of hemodynamics during transplantation and treatment of severe lung dysfunction and primary graft failure. Modulation of heme oxygenase-1 expression, ischemic conditioning and gene therapy are future directions for pulmonary reperfusion injury management.

Key words: cardiopulmonary bypass, pulmonary hypertension, respiratory insufficiency

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Comparison of haemodynamic parameters between the high and low spinal block in young healthy patients

Abstract

Background. For some surgical procedures a higher sensory block is needed. However, it is complicated by a higher incidence of hypotension, more bradycardia and nausea and a higher use of vasoactive drugs. In elderly and obstetric population complications have been attributed to the decrease in cardiac output and systemic vascular resistance, especially in a high block (above Th6). The aim of our study was to find the incidence of hypotension and bradycardia after a spinal anaesthesia in young, healthy patients. As young patients compensate more, we aimed to find the difference in haemodynamic variables between the group with a high and the group with a low spinal block and the underlying mechanisms of hypotension.

Methods. In a prospective, randomized study 44 American Society of Anaesthesiologists (ASA) 1 patients scheduled for knee arthroscopy under spinal anaesthesia were randomly distributed to a high (group H) and a low (group L) spinal block group. In a group H patients were placed into horizontal, whereas in a group L in 15-degree anti-Trendelenburg position immediately after the spinal block. Haemodynamic parameters were measured continuously noninvasively from 10 min before to 25 min after the spinal block using the CNAPTM device with the LiDCORapid monitor.

Results. The differences in haemodynamic parameters between the groups were not statistically significant at all measured times despite a significant difference in the spinal block level (18.5 vs 13.3 dermatomes above S5, p<0.001) and a significant difference in haemodynamic variables inside each group compared to the baseline value. With cardiac index (CI) as a dependent variable, a significant correlation between CI and stroke volume index (SVI) was found (β=0.849, p<0.001) and also between CI and heart rate (HR) (β=0.573, p<0.001). In group H the incidence of hypotension was 35%, whereas in group L it was 10%. The same difference was seen in the use of phenylephrine between the groups, however the difference was not significant.

Conclusion. In our study it was found that in young, healthy patients there are no significant differences in haemodynamic parameters and in incidence of hypotension between a high and low spinal block. Young, healthy patients compensate a decrease in systemic vascular resistance caused by the spinal anaesthesia with a compensatory increase in CI resulting from an increase in SVI and HR. However, a trend towards less hypotension, less bradycardia and less frequent phenylephrine use in a low spinal block was noted.

Key words: spinal anaesthesia, hyperbaric bupivacaine, haemodynamic parameters, cardiac output, hypotension

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Impact of gravitational interaction between the Moon and the Earth on the occurrence of episodes of cardiogenic pulmonary edema in the field

Abstract

While circadian variation of occurrence of cardiovascular emergencies has been described, it has not been assessed whether fluctuations of gravitational interaction between the Earth and the Moon may induce other types of its variation in time have the similar impact. Therefore, we decided to evaluate whether there is an association between the occurrence of prehospital cardiogenic pulmonary edema (CPE) episodes treated by Emergency Medical Services (EMS) and fluctuations in the intensity of gravitational interaction between the Earth and the Moon.

Methods. We extracted all dispatches to CPE episodes from the EMS database of the Central Bohemian Region, Czech Republic, between 2.11.2008 and 1.7.2014. For each episode, the intensity of gravitational interaction between the Moon and the Earth was calculated. The study period was divided into 11 sections of equal duration according to the different intensity of gravitational interaction, and occurrence of CPE was compared among the groups.

Results. We observed up to 4,744 episodes of CPE during the study period. Occurrence of CPE episodes was highest in the periods with the weakest intensity of gravitational interaction (≤1.80e1026 N), while in the periods of the most intense gravitational interaction (≥2.26e1026 N), the lowest proportion of CPE cases was observed (23.44 vs. 3.79 %, p <0.001).

Conclusions. We identified a significant association between the intensity of gravitational interaction between the Earth and the Moon and occurrence of CPE, treated by our EMS. The weakest intensity was associated with its increased occurrence and vice versa. Further research is required for potential use of this phenomenon in a chronotherapeutic approach to secondary prevention of CPE.

Key words: cardiogenic pulmonary edema, gravitational interaction

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Influence of rescuer strength and shift cycle time on chest compression quality

Abstract

Introduction. Previous studies have suggested that differences in rescuer strength and compression shift cycle are strongly associated with the quality of chest compression. We hypothesised that changing the shift cycle from two minutes to one would have a positive effect on the quality of chest compression in two-rescuer cardiopulmonary resuscitation (CPR), regardless of rescuer strength.

Methods.Thirty-nine senior medical students participated in this prospective, simulation-based, crossover study. After evaluation of muscle strength using a handgrip dynamometer, each participant was required to perform two sets of compressions separated by a 15-minute rest. Participants started with either four cycles of chest compressions for one minute followed by a one-minute rest (1-MCS), or with two cycles of chest compressions for two minutes followed by a two-minute rest (2-MCS). After a 15-minute break, participants switched groups and performed the other set of compressions. Mean compression depth (MCD), mean adequate compression (MAC), and adequate compression ratio (ACR) per minute were measured for each group. Subjective fatigue was reported after the completion of each set of compression cycles. Results. Rescuer strength was strongly correlated with MCD (p <0.01), MAC ratio (p <0.01), and ACR (p <0.01), and cycle group was correlated with MCD (p <0.01) and ACR (p =0.03). Subjective fatigue with 1-MCS was lower than with 2-MCS, regardless of rescuer strength.

Conclusion. We found that the quality of chest compressions could be improved by changing the shift cycle from two minutes to one, regardless of rescuer strength. Therefore, reducing the existing shift cycle recommended in guidelines for two rescuers could be beneficial.

Key words: CPR, fatigue, hand strength

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Middle latency auditory evoked potential index for prediction of post-resuscitation survival in elderly populations with out-of-hospital cardiac arrest

Abstract

Background. Out-of-hospital cardiac arrest (OHCA) is associated with a high mortality rate in the elderly. Although most reports have investigated among elderly patients with OHCA until 1990s, non-invasive monitorings cannot presently predicted cerebral resuscitation during cardiopulmonary resuscitation (CPR). Findings of a previous study suggest that monitoring of middle latency auditory evoked potentials (MLAEP) during CPR could provide an indicator of effective post-resuscitation survival.

Objectives. We speculated that the MLAEP index (MLAEPi), measured in an emergency room, can predict post-resuscitation survival among elderly patients with OHCA.

Methods. This prospective study included 31 elderly patients aged ≥65 years with OHCA who received basic life support (BLS) and did not achieve restoration of spontaneous circulation (ROSC) until arrival at the emergency center between December 2010 and December 2011. All patients were administered advanced cardiac life support (ACLS) in the emergency room. Initial MLAEPi was measured using an MLAEP monitor (aepEX plus®, Audiomex, UK) during the first cycle of ACLS. Prediction of the post-resuscitation survival was investigated.

Results. Eight patients who achieved ROSC were admitted to our hospital and 23 did not achieve ROSC in the emergency room. Initial MLAEPi was significantly higher in patients with than without ROSC (median, 33 vs. 26, p = 0.02). Three survivors, among patients with ROSC, were discharged from our hospital (survivors) and 5 died during hospitalization (non-survivors). Initial MLAEPi was significantly higher in survivors than in non-survivors (median, 35 vs. 28, p = 0.03) or patients without ROSC (median, 35 vs. 26, p < 0.01).

Conclusions. MLAEPi satisfactorily denotes cerebral function and predicts post-resuscitation survival in elderly populations.

Key words: cardiopulmonary resuscitation, basic life support, advanced cardiac life support, age, monitoring, critical care

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