Thomas J. Nuckton

Diabetes mellitus: a negative predictor for the development of acute respiratory distress syndrome from septic shock.

I n this issue of Critical Care Medicine, Dr. Moss and colleagues (1) provide the first prospective study that identifies a clinical disorder associated with a decreased incidence of acute respiratory distress syndrome (ARDS)— diabetes mellitus. Of 113 patients with septic shock, the authors identified 32 (28%) with a history of diabetes mellitus as defined by a prescription for insulin or use of an oral hypoglycemic agent. The incidence of ARDS was strikingly lower in the diabetic patients compared with the nondiabetic patients (25% vs. 47%; odds ratio 5 0.33, 95% confidence interval 0.12– 0.90). Until now, the potential effect of diabetes on the incidence of ARDS and mortality largely has been overlooked. In fact, the prevalence of diabetes mellitus is not mentioned in most studies of ARDS or sepsis. The discovery of a lower incidence of ARDS among diabetic patients has important implications for the design of future studies. The major strength of this study is the prospective, multicenter design and the use of multivariate logistic regression for statistical analysis. The inclusion of only patients with septic shock is an additional strength for two reasons. First, sepsis is the most common and most lethal cause of ARDS (2). Second, the diagnosis of sepsis was defined clearly by objective criteria. Also, the overall incidence of ARDS in this study was similar to other studies of septic patients. Therefore, the results of this study can be generalized with greater confidence. There are, however, some limitations to this study. First, the definition of diabetes mellitus may have been too restrictive, because patients with diabetes controlled by diet or undiagnosed type 2 diabetes may have been excluded. Furthermore, combining all patients with type I and II diabetes without specifying the need for insulin may be suboptimal, because the molecular and genetic basis for diabetes in these patients is heterogeneous (3). Consequently, the underlying factors influencing the development of ARDS may not be uniform among these diabetic patients. As the authors point out, it may have been preferable to determine hemoglobin A1 levels in all patients as an additional marker of disease and as a measure of diabetes control. Using a prior prescription for insulin or an oral hypoglycemic agent as the definition of diabetes also may select for patients who received better medical care before admission. A second potential limitation to this study is that the association between the incidence of ARDS and diabetes mellitus becomes weaker when the admission glucose values are compared. By using a plasma glucose concentration of 120 mg/dL as a threshold, the incidence of ARDS for patients with hyperglycemia was 33% (22/66) compared with 51% (24/ 47) in the patients with normal plasma glucose (p 5 .06). In a subgroup analysis of the 81 nondiabetic patients, nearly half of whom had an elevated admission plasma glucose, the incidence of ARDS in patients with hyperglycemia was 39% (15/39) compared with 55% (23/42) in the patients with normal plasma glucose (p 5 0.1). These differences are not statistically significant, but a trend toward a lower incidence of ARDS in hyperglycemic patients is apparent. This trend might have been less evident if blood glucose had been analyzed as a continuous variable rather than as a discontinuous variable, that is, above or below 120 mg/dL. Therefore, hyperglycemia may not be the only factor influencing the development of ARDS, although it is one of the most obvious abnormalities in diabetics. However, given the small sample size, a type II error may have occurred when only plasma glucose levels were considered. A larger number of patients, perhaps in association with hemoglobin A1 levels, might have sorted out this potential additional association. What are the mechanisms of protection against ARDS in diabetic patients? Are diabetics protected because of impaired neutrophil function or altered neutrophil-endothelial interactions, or are they protected by hyperglycemia and an associated hyperosmolar state? Perhaps both mechanisms are important. It is well known that neutrophils from diabetics have impaired biological responses, including reduced bactericidal activity and impaired chemotaxis (4, 5). Neutrophil adhesion to the endothelium also can be altered in diabetics (6, 7). These abnormalities could attenuate neutrophil-dependent lung injury in patients with septic shock. Alternatively, hyperglycemia may have an independent effect on neutrophil or endothelial properties, resulting in decreased injury in response to bacteria or endotoxin (4). Future studies could be designed to better distinguish these possibilities. These studies should include a more comprehensive definition of diabetes mellitus including diabetes controlled by diet alone and diabetes as indicated by hemoglobin A1 concentrations, plasma glucose concentrations, and serum osmolality. In addition, it might be useful to measure plasma markers of acute lung injury that have shown some promise in prior studies. For example, measurement of von Willebrand factor-antigen (8), intracellular adhesion molecule-1 (9), and tumor necrosis factor receptors may be valuable. These biological markers might have some additional positive or negative predictive value when coupled with the presence or absence of diabetes mellitus. Although Dr. Moss and colleagues (1 focus primarily on the incidence of ARDS among diabetic patients, the issue of mortality also should be considered. In the current study, mortality was not different between the diabetics and nondiabetics with ARDS (50% vs. 63%, p 5 .5). If decreased lung injury was responsible for the lower incidence of ARDS, one

HYPOTHERMIA FROM PROLONGED IMMERSION: BIOPHYSICAL PARAMETERS OF A SURVIVOR

We report a case of survival following prolonged immersion and hypothermia. The patient survived for over 9 h in open water, after his vessel capsized and sank in the Pacific Ocean off the coast of Northern California. Water temperature on the day of the sinking was 14.4 degrees C (58.0 degrees F). Although he did have adequate flotation, the patient did not wear a survival suit. On initial physical examination in the Emergency Department (ED), the patients rectal temperature was 30.0 degrees C (86.0 degrees F). With active rewarming, his temperature returned to normal (37.0 degrees C (98.6 degrees F)) within 5 h. Body fat of the patient was 19.6%, near the 50th percentile for his age (19.0%). Surface/volume ratio of the patient (.0228 m(2)/L) was 19% smaller than a predicted average (.0282 m(2)/L). We believe that the patients large body habitus contributed to survival and that surface/volume ratio was likely the biophysical variable most closely associated with decreased cooling.

Trends in the utilisation of emergency departments in California, 2005–2015: a retrospective analysis

Objective To examine current trends in the characteristics of patients visiting California emergency departments (EDs) in order to better direct the allocation of acute care resources. Design A retrospective study. Setting We analysed ED utilisation trends between 2005 and 2015 in California using non-public patient data from California’s Office of Statewide Health Planning and Development. Participants We included all ED visits in California from 2005 to 2015. Primary and secondary outcome measures We analysed ED visits and visit rates by age, sex, race/ethnicity, payer and urban/rural trends. We further examined age, sex, race/ethnicity and urban/rural trends within each payer group for a more granular picture of the patient population. Additionally, we looked at the proportion of patients admitted from the ED and distribution of diagnoses. Results Between 2005 and 2015, the annual number of ED visits increased from 10.2 to 14.2 million in California. ED visit rates increased by 27.8% (p<0.001), with the greatest increases among patients aged 5–19 (37.4%, p<0.001) and 45–64 years (41.1%, p<0.001), non-Hispanic Black and Hispanic patients (56.8% and 48.8%, p<0.001), the uninsured and Medicaid-insured (36.1%, p=0.002; 28.6%, p<0.001) and urban residents (28.3%, p<0.001). The proportion of ED visits resulting in hospitalisation decreased by 18.3%, with decreases across all payer groups. Conclusions Our findings reveal an increasing demand for emergency care and may reflect current limitations in accessing care in other parts of the healthcare system. Policymakers may need to recognise the increasingly vital role that EDs are playing in the provision of care and consider ways to incorporate this changing reality into the delivery of health services.

California Sea Lion (Zalophus californianus) and Harbor Seal (Phoca vitulina richardii) Bites and Contact Abrasions in Open-Water Swimmers: A Series of 11 Cases

OBJECTIVE To review cases of bites and contact abrasions in open-water swimmers from California sea lions (Zalophus californianus) and harbor seals (Phoca vitulina richardii). METHODS Open-water swimmers from a San Francisco swimming club were questioned about encounters with pinnipeds (seals and sea lions) that resulted in bites or contact abrasions. When possible, wounds were documented with photographs. Medical follow-up and treatment complications were also reviewed. RESULTS From October 2011 to December 2014, 11 swimmers reported bites by a sea lion (n = 1), harbor seal (n = 7), or unidentified pinniped (n = 3). Ten of the encounters occurred in San Francisco Bay; 1 occurred in the Eld Inlet, in Puget Sound, near Olympia, WA. None of the swimmers were wearing wetsuits. All bites involved the lower extremities; skin was broken in 4 of 11 bites and antibiotics were prescribed in 3 cases. One swimmer, who was bitten by a harbor seal, also had claw scratches. A treatment failure occurred with amoxicillin/clavulanate in another swimmer who was bitten by an unidentified pinniped; the wound healed subsequently with doxycycline, suggesting an infection with Mycoplasma spp. There were no long-lasting consequences from any of the bites. The majority of cases occurred at low tide, and bumping of the swimmer by the animal before or after a bite was common, but no clear tide or attack pattern was identified. CONCLUSIONS Bites and contact abrasions from sea lions and harbor seals are reported infrequently in open-water swimmers and typically involve the lower extremities. Because of the risk of Mycoplasma infection, treatment with a tetracycline is recommended in pinniped bites with signs of infection or serious trauma. Attempting to touch or pet sea lions or seals is inadvisable and prohibited by the Marine Mammal Protection Act. Swimmers should leave the water as soon as possible after a bite or encounter.