Adrenergic vasopressor agents and mechanical ventilation for the treatment of experimental septic shock

Mechanical ventilation preserves diaphragm mitochondrial function in a rat sepsis model

BACKGROUND

To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis.

METHODS

A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 h after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the proinflammatory interleukin-1β (IL-1β) in diaphragms.

RESULTS

CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1β mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome c oxidase activity.

CONCLUSION

In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

Pralidoxime improves the hemodynamics and survival of rats with peritonitis-induced sepsis

Several studies have suggested that sympathetic overstimulation causes deleterious effects in septic shock. A previous study suggested that pralidoxime exerted a pressor effect through a mechanism unrelated to the sympathetic nervous system; this effect was buffered by the vasodepressor action of pralidoxime mediated through sympathoinhibition. In this study, we explored the effects of pralidoxime on hemodynamics and survival in rats with peritonitis-induced sepsis. This study consisted of two sub-studies: survival and hemodynamic studies. In the survival study, 66 rats, which survived for 10 hours after cecal ligation and puncture (CLP), randomly received saline placebo, pralidoxime, or norepinephrine treatment and were monitored for up to 24 hours. In the hemodynamic study, 44 rats were randomly assigned to sham, CLP-saline placebo, CLP-pralidoxime, or CLP-norepinephrine groups, and hemodynamic measurements were performed using a conductance catheter placed in the left ventricle. In the survival study, 6 (27.2%), 15 (68.1%), and 5 (22.7%) animals survived the entire 24-hour monitoring period in the saline, pralidoxime, and norepinephrine groups, respectively (log-rank test P = 0.006). In the hemodynamic study, pralidoxime but not norepinephrine increased end-diastolic volume (P <0.001), stroke volume (P = 0.002), cardiac output (P = 0.003), mean arterial pressure (P = 0.041), and stroke work (P <0.001). The pressor effect of norepinephrine was short-lived, such that by 60 minutes after the initiation of norepinephrine infusion, it no longer had any significant effect on mean arterial pressure. In addition, norepinephrine significantly increased heart rate (P <0.001) and the ratio of arterial elastance to ventricular end-systolic elastance (P = 0.010), but pralidoxime did not. In conclusion, pralidoxime improved the hemodynamics and 24-hour survival rate in rats with peritonitis-induced sepsis, but norepinephrine did not.

Early septic shock induces loss of oxidative phosphorylation yield plasticity in liver mitochondria

We aimed to study the change in mitochondrial oxidative phosphorylation efficiency occurring at the early stage of septic shock in an experimental model. Thirty-six male Wistar rats were divided into two groups. In the first group, a cecal ligation and puncture (CLP) was carried out to induce septic shock for 5 h. The second group includes sham-operated rats and constitutes the control group. Blood gas analysis, alanine amino transferase, and lactic acid dosages were assayed 5 h after surgery. Liver mitochondria were isolated for in vitro functional characterization, including mitochondrial respiratory parameters, oxidative phosphorylation efficiency, oxi-radical production, membrane potential, and cytochrome c oxidase activity and content. Liver interleukin 1β (IL-1β) and tumor necrosis α mRNA levels were determined. Septic shock induced a severe hypotension occurring 180 min after CLP in association with a metabolic acidosis, an increase in plasma alanine amino transferase, liver IL-1β gene expression, and mitochondrial reactive oxygen species production. The rates of mitochondrial oxygen consumption and the activity and content of cytochrome c oxidase were significantly decreased while no alterations in the oxidative phosphorylation efficiency and inner membrane integrity were found. These results show that contrary to what was expected, liver mitochondria felt to adjust their oxidative phosphorylation efficiency in response to the decrease in the mitochondrial oxidative activity induced by CLP. This loss of mitochondrial bioenergetics plasticity might be related to mitochondrial oxidative stress and liver cytokines production.

Part 10: Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Note From the Writing Group: Throughout this article, the reader will notice combinations of superscripted letters and numbers (eg, “Family Presence During ResuscitationPeds-003”). These callouts are hyperlinked to evidence-based worksheets, which were used in the development of this article. An appendix of worksheets, applicable to this article, is located at the end of the text. The worksheets are available in PDF format and are open access.

Time course of liver nitric oxide concentration in early septic shock by cecal ligation and puncture in rats

An overwhelming nitric oxide (NO) production is a crucial step in the circulatory events as well as in the cellular alterations taking place in septic shock. However, evidences of this role arise from studies assessing the NO production on an intermittent basis precluding any clear evaluation of temporal relationship between NO production and circulatory alterations. We evaluated this relationship by using a NO specific electrode allowing a continuous measurement of NO production. Septic shock was induced by a cecal ligation and puncture (CLP) in a first group of anesthetized rats. After the same CLP, a second group received a selective iNOS inhibitor (L-NIL). Control rats were sham operated or sham operated with L-NIL administration. While NO concentration was measured every 2 min by a NO-sensitive electrode over 7h following CLP, the liver microcirculation was recorded by a laser-Doppler flowmeter. CLP induced a severe septic shock with hypotension occurring at a mean time of 240 min after CLP. At the same time, an increase in liver NO concentration was observed, whereas a decrease in microvascular liver perfusion was noted. In the septic shock group, L-NIL administration induced an increase in arterial pressure whereas the liver NO concentration returned to baseline values. In addition, shock groups experienced an increase in iNOS mRNA. These data showed a close temporal relationship between the increase in liver NO concentration and the microvascular alteration taking place in the early period of septic shock induced by CLP. The iNOS isoform is involved in this NO increase.

Liberal vs. conservative vasopressor use to maintain mean arterial blood pressure during resuscitation of septic shock: an observational study

OBJECTIVE

The optimal role of vasopressor therapy in septic shock is not known. We hypothesized that the variability in the use of vasopressors to treat hypotension is associated with subsequent organ failures.

DESIGN

Retrospective observational single-center cohort study.

SETTING

Tertiary care hospital.

PATIENTS AND PARTICIPANTS

Consecutive patients with septic shock.

MEASUREMENT AND RESULTS

Ninety-five patients were enrolled. Serial blood pressure recordings and vasopressor use were collected during the first 12h of septic shock. Median duration of hypotension that was not treated with vasopressors was 1.37h (interquartile range [IQR] 0.62-2.66). Based on the observed variability, we evaluated liberal (duration of untreated hypotension < median) vs. conservative (duration of untreated hypotensionn > median) vasopressor therapy. Compared with patients who received conservative vasopressor therapy, patients treated liberally had similar baseline organ impairment [median Sequential Organ Failure Assessment (SOFA) score 8 vs. 8, p = 0.438] were more likely to be younger (median age 70 vs. 77 years, p = 0.049), to require ventilator support (78 vs. 49%, p < 0.001), and to have progression of organ failures after 24h (59 vs. 37%, p = 0.032). When adjusted for age and mechanical ventilation, early therapy aimed at achieving global tissue perfusion [odds ratio (OR) 0.33, 95% confidence interval (CI) 0.11-0.88), and early adequate antibiotic therapy (OR 0.27, 95% CI 0.09-0.76), but not liberal vasopressor use (OR 2.13, 95% CI 0.80-5.84), prevented progression of organ failures.

CONCLUSIONS

In our retrospective study, early adequate antibiotics and achieving adequate global perfusion, but not liberal vasopressor therapy, were associated with improved organ failures after septic shock. Clinical trials which compare conservative vs. liberal vasopressor therapy are warranted.

Traumatic Shock Alias Posttrauma Critical Illness

Trauma is the most common cause of death under the age of 45. Many trauma patients die of multiple organ failure, especially acute respiratory distress syndrome. The basic cause of traumatic shock has only partially been elucidated. Data resources include research papers on the subject of trauma and shock from 1875 to the present. These papers numbered more than 40,000. Almost all of the papers proposed that traumatic shock was due to hypovolemia. The concept of a shock toxin as promulgated during World War I is correct. This toxin is a thrombogenic aminophospholipid that occurs only on the inner layer of all cell membranes and is liberated by cell destruction. It causes disseminated intravascular coagulation, which may obstruct the microcirculation of any and all organs producing multiple organ failure by microclots. These microclots may be lysed by plasminogen activator and circulation to the organs restored.

A Review of Septic Shock

The mortality of septic shock, both in percentage of septic shock cases and total number of septic shock cases, has been increasing over the past several decades. This is despite major advances in diagnosis and treatment. The basic cause of traumatic and septic shock has only partially been elucidated. This review presents information about the basic cause and mechanism of septic shock as well as a new treatment based on this information. Data sources include research papers on the subject of septic shock from 1875 until the present. These papers numbered more than 10,000, most of which are not included in the reference list because many are duplicative. The main result of the review of literature is that all of a wide variety of treatments of septic shock have not resulted in a lowering of mortality, but in fact have increased it. Another toxin (in addition to endotoxin and its secondarily induced host mediators) is proposed. This toxin causes disseminated intravascular coagulation, which may obstruct the microcirculation of any and all organs, producing multiple organ failure by microclots. These microclots may be lysed by plasminogen activator and circulation to the organs restored.

Traumatic and septic shock alias post-trauma critical illness

BACKGROUND

The mortality associated with septic shock, both in percentage of septic shock cases and total number of septic shock cases, has been increasing over the past several decades. This is despite major advances in diagnosis and treatment. The basic cause of traumatic and septic shock has been only partially elucidated.

METHODS

Data sources include research papers on the subject of traumatic and septic shock from 1875 to the present. These papers numbered over 10 000, few of which are included in the reference list because many are duplicative or negative. Over 1000 articles were reviewed which documented the unsuccessful search for a treatment for septic shock based on the theory that septic shock is due to endotoxin and its secondarily induced host mediators. These references are available from the author.

RESULTS

and conclusion The concept of a shock toxin in trauma and sepsis as promulgated during World War I is correct. This toxin is a thrombogenic aminophospholipid which occurs only on the inner layer of all cell membranes and is liberated by cell destruction. It causes disseminated intravascular coagulation which may obstruct the microcirculation of any or all organs, producing multiple organ failure by microclots. These microclots may be lysed by plasminogen activator and circulation to the organs restored.

Effect of the type IV phosphodiesterase inhibitor Ro 20-1724 on catecholamine-induced alterations in regional vascular resistance and regional blood flow

Type IV phosphodiesterase inhibitors have been studied in multiple disease processes that commonly afflict patients who are treated with catecholamine infusions. To examine whether type IV phosphodiesterases alter catecholamine-induced changes in systemic and regional hemodynamic parameters, we examined the effects of Ro 20-1724 on rats during dobutamine, epinephrine, isoproterenol, and norepinephrine infusions. Twenty-six Sprague-Dawley rats received either Ro 20-1724 or vehicle. After central and regional hemodynamic monitoring was initiated, animals received increasing doses of two of the four catecholamines. In the absence of catecholamines, Ro 20-1724 infusion caused a significant increase in heart rate and a trend toward an increase in superior mesenteric artery blood flow. Ro 20-1724 attenuated the increase in blood pressure caused by epinephrine but had no effect on the dobutamine-, isoproterenol-, or norepinephrine-induced changes in blood pressure. Ro 20-1724 had no effect on catecholamine-induced changes in renal, carotid, and hindquarter vascular resistance but did attenuate the decrease in superior mesenteric artery vascular resistance caused by isoproterenol. Type IV phosphodiesterase inhibition in combination with catecholamines has no adverse effects on regional hemodynamics; however, it can inhibit the ability of epinephrine infusion to increase blood pressure.