Mine waste disposal leads to lower coral cover, reduced species richness and a predominance of simple coral growth forms on a fringing coral reef in Papua New Guinea.

A large gold mine has been operating at the Lihir Island Group, Papua New Guinea since 1997. The mine disposes of waste rock in nearshore waters, impacting nearby coral communities. During 2010, 2012 we conducted photographic surveys at 73 sites within 40 km of the mine to document impacts of mining operations on the hard coral communities. Coral communities close to the mine (∼2 km to the north and south of the mine) were depaurperate, but surprisingly, coral cover and community composition beyond this range appeared to be relatively similar, suggesting that the mine impacts were limited spatially. In particular, we found mining operations have resulted in a significant decrease in coral cover (4.4% 1.48 km from the disposal site c.f. 66.9% 10.36 km from the disposal site), decreased species richness and a predominance of less complex growth forms within ∼2 km to the north and south of the mine waste disposal site. In contrast to the two 'snapshot' surveys of corals performed in 2010 and 2012, long term data (1999-2012) based on visual estimates of coral cover suggested that impacts on coral communities may have been more extensive than this. With global pressures on the world's coral reefs increasing, it is vital that local, direct anthropogenic pressures are reduced, in order to help offset the impacts of climate change, disease and predation.

Effect of a ground critical care transport service on air medical helicopter utilization.

OBJECTIVE: To investigate the effect of adding a ground critical care ambulance service on the utilization of the pre-existing helicopter air ambulance. METHODS: A retrospective review of the requests for the helicopter was performed during each of three periods: one year prior to initiation of the ground service; the first six months after initiation of the ground service, during which the ground critical care ambulance operated 12 hours daily; and the subsequent six months, during which the ground critical care ambulance operated 24 hours daily. To control for any increase in the demand for health care services, hospital admission rates were used to standardize the helicopter utilization data. Means were compared using ANOVA. RESULTS: Prior to initiation of the ground service, flight requests averaged 82 per month. During the period when the ground service was in place on a 24-hour basis, flight requests averaged 105 per month, a significant increase (p = 0.0010). Although hospital admissions during the same period increased (2,410 to 2,624, p = 0.0001), demand for the helicopter service increased at a faster rate. Flights per 100 admissions increased from 2.3 to 2.9, which is statistically significant (p = 0.0152). CONCLUSION: The attempt to decrease the demand for a helicopter air ambulance by initiating a parallel ground ambulance service was not successful. Programs adding a ground critical care ambulance to existing helicopter services should not expect a decrease in utilization of the helicopter. These services should be viewed as complementary but not interchangeable.

Unnecessary intravenous access in the emergency setting.

OBJECTIVE: To determine the rate of unnecessary intravenous (IV) access in the emergency setting. METHODS: Retrospective chart review of all patients who presented to a rural, academic emergency department (ED) for the study period of June 1 through June 10, 1997. Categorical data and elapsed time to treatment are reported significant at p < 0.05. RESULTS: 1,342 charts were reviewed; of these, 940 patients were enrolled. 402 patients were excluded for: age <18 years, direct admission, or inadequate charting. Emergency medical services (EMS) transported 278 patients and initiated 84 IVs in the field (30%). 90 of the remaining EMS patients had IV access initiated in the ED (32%). 662 patients presented by other means and 175 were given IVs (26%). Of the IVs initiated in the field, 32 (38%) were used, whereas 122 (46%) of the ED-initiated IVs were used. When all data were combined, only 154 (44.0%) of the 349 patients who had IV access obtained received treatment through the IV. The elapsed time to treatment for patients with IVs initiated by EMS but treatment in the ED was 25.9 minutes, which was not different from that for patients who received both IV and treatment in the ED (28.3 minutes). CONCLUSIONS: A significant percentage of IVs initiated in the emergency setting are used inappropriately. IV access without treatment in the field did not improve elapsed time to treatment once patients arrived to the ED. In an era of diminishing health care budgets, further study and strict examination of the cost-benefit ratio ensure maximal utilization of emergent IV access.

Threshold, enzymatic, and pathologic changes associated with prolonged transcutaneous pacing in a chronic heart block model.

Previous studies have shown that 30 minutes of transcutaneous cardiac pacing (TCP) can induce mild, clinically insignificant myocardial damage. Longer use of TCP may cause more severe cardiac damage which might result in an increase in the capture threshold for subsequent transvenous cardiac pacing (TVP). To assess this possibility, we examined changes induced by TCP in a canine chronic heart block model. Heart block was induced in conditioned dogs (n = 8) by His bundle ablation. Seven to 10 days after induction of heart block, six animals were paced. Cardiac enzymes were drawn before pacing and at 4, 24, 48, and 72 hours after pacing. Although there was a significant rise in CK at 4 and 24 hours (P less than 0.05), there was no detectable rise in the MB fraction in any of the paced animals. There was no elevation of LDH after pacing, although three animals did develop an LDH1/LDH2 isoenzyme flip indicative of myocardial damage. Animals were sacrificed 72 hours after pacing and their hearts were examined for gross and microscopic changes. The hearts of the paced animals revealed subendocardial, subepicardial, and perivascular areas of basophilic degeneration involving less than 1% of the myocardium in four of six animals. No evidence of such damage was seen in two heart-blocked control animals not undergoing pacing. TVP and TCP capture thresholds assessed before and after a 60-minute TCP pacing period showed no significant change. Hence, use of TCP for a 60-minute period prior to TVP appears to be a safe emergency pacing technique.

Hemodynamics of transcutaneous cardiac pacing.

Transcutaneous cardiac pacing has recently been rediscovered as a rapid means of initiating emergency cardiac pacing. Potential myocardial injury from extended transcutaneous pacing could adversely affect cardiac hemodynamics during pacing. This canine study compares the hemodynamics of transcutaneous and transvenous cardiac pacing in animals with induced chronic heart block. One to two weeks following chemical ablation of the His bundle, hemodynamic measurements were made during 60 minutes of transcutaneous and 5-minute periods of conventional right ventricular endocardial pacing. Cardiac index and output were found to increase significantly (P less than 0.005), and systemic vascular resistance was found to decrease significantly (P less than 0.005) from baseline values with both pacing techniques. A hemodynamic difference between pacing techniques was evident only for mean arterial blood pressure; pressure measurements during transvenous pacing were slightly greater than those during transcutaneous cardiac pacing. The hemodynamic measurements were found to be stable during a 60-minute period of transcutaneous cardiac pacing. This study demonstrates that transcutaneous cardiac pacing is as effective hemodynamically as conventional transvenous pacing in animals with induced chronic heart block.