Prognosis in severe shock

Survival of severely shocked patients who present with absent radial pulse and unrecordable blood pressure in the pre-hospital phase

OBJECTIVES

To determine the mortality and clinical features of patients presenting with severe hypotension in the pre-hospital phase of care.

DESIGN

A prospective observational study. The medical records of patients attended by a physician-led pre-hospital medical service were examined prospectively. Inclusion criteria were severe shock characterized by a non-palpable radial pulse and unrecordable blood pressure at clinical presentation. All consecutive records between September 2002 and September 2003 were included.

SETTING

Seine Saint-Denis, an urban area with a population of 1.5 million located in the northern suburbs of Paris, France.

INTERVENTIONS

None.

RESULTS

One hundred and thirty one patients met the inclusion criteria. The overall mortality was 50% (66/131). Of the deaths, 20% (13/66) occurred in the pre-hospital phase and 80% (53/66) after arrival in hospital. Clinical features significantly associated with increased mortality were: more than one pre-existing co-morbidity, increased age, high Knaus score, a low Glasgow Coma Score, vasopressor administration, pre-hospital cardiac arrest and hypotension on arrival at hospital. The presence of anaphylactic shock was associated with low mortality. In multivariate analysis, occurrence of cardiac arrest (OR=13.5 [2.8; 64.5]), age (OR=1.03 [1.01; 1.05]) and low Glasgow Coma Scale score value (OR=1.15 [1.05; 1.29]) were independently associated with mortality.

CONCLUSION

Patients presenting with profound hypotension in the pre-hospital phase have a high mortality. Patients who recover their blood pressure with interventions before hospital admission and those with anaphylactic shock have a better outcome than other patient sub-groups.

Prostacyclin but not phentolamine increases oxygen consumption and skin microvascular blood flow in patients with sepsis and respiratory failure

Inadequate tissue oxygenation may occur in critically ill patients with sepsis despite an apparently adequate O2 transport (QO2), and this may contribute to the development of an O2 debt and also to multiple organ failure. It has been shown that increasing QO2 by infusing a vasodilator may reveal this O2 debt in septic patients. To investigate whether the site of action of vasodilators may be of importance in unmasking such an O2 debt, we administered prostacyclin, a prostaglandin with a preferential effect on the microcirculation, and phentolamine, an arteriolar vasodilator, in 11 patients studied during the first 48 hours after the onset of sepsis, and compared their effect on whole body oxygen consumption (VO2) and skin microvascular blood flow. The results demonstrated that increasing QO2 by prostacyclin but not by phentolamine significantly increases VO2 in critically ill patients with sepsis. The site of action of vasodilators may therefore play an important role in their ability to unmask an O2 debt.

Considerations in the therapy of septic shock

In summary, gram-negative sepsis is unique among infectious illnesses in that it is a disorder that recruits endogenous physiologic processes to mediate tissue injury. This host damage frequently occurs in the absence of microbial invasion of affected organs. The resultant hypotension, coagulation defects, and organ dysfunction may be associated with serious morbidity or may contribute to mortality. Ultimately, however, mortality in patients with septic shock depends on the nature of the infectious process and the severity of the underlying illnesses. Unfortunately, attempts to aggressively treat septic patients with a formidable array of antimicrobial and pharmaceutical agents have not remarkably reduced mortality. Nor does it seem likely that future elucidation of the inflammatory mechanisms of sepsis will lead to the generation of therapeutic agents that will significantly improve survival. On the other hand, prophylactic or therapeutic modalities that deter colonization or invasion by pathogenetic organisms or that alter the ability of pathogens to evoke adverse host responses may be more likely to impact on the incidence and morbidity of gram-negative bacillary infections. Until modifications in the initial interactions of gram-negative pathogens with human hosts can be realized, the mortality of gram-negative sepsis is likely to remain high.

The role of isotonic and hypertonic solutions in the resuscitation of shocked patients

The role of intravenous salt solutions in resuscitation is reviewed historically. A brief account of the pathophysiology of shock is given. The particular use of hypertonic solutions in the resuscitation of severely shocked patients is reviewed and its mechanism of action discussed. It is considered that hypertonic solutions may find a role in any future major military conflict. Two hypertonic solutions that are suggested for consideration in this context are 12% sodium chloride (2 mmol/ml) and 8.4% sodium bicarbonate (1 mmol/ml).