Bubble model vs. Gradient Factors redux

[EFX]

I disagree, You can't purposely bend divers with current informed consent. That was he Navy. I think that bubble detection, and other surrogate markers will have to do with regard to data collection.

Bending divers is a hard moral decision but to use other surrogate markers you have to first correlate those markers with DCS injuries.

 

[scubadada]

Bending divers is a hard moral decision but to use other surrogate markers you have to first correlate those markers with DCS injuries.

Yes, I have recently asked @Dr Simon Mitchell what he thought of the various surrogate endpoints

 

[rjack321]

Bending divers is a hard moral decision but to use other surrogate markers you have to first correlate those markers with DCS injuries.

The NEDU study was terminated before it was even finished because it wasnt ethical to continue inflicting the subjects in the deep stop arm with the added risk.

 

[elmo]

The NEDU study was terminated before it was even finished because it wasnt ethical to continue inflicting the subjects in the deep stop arm with the added risk.

I believe the study was finished. It was concluded after a mid-trial assessment determined there was sufficient data to dismiss the hypothesis that the deep stops model was better than the Navy's current practice. Had the rates of dcs been similar between the two dive schedules then the trials would have continued.

 

[rjack321]

I believe the study was finished. It was concluded after a mid-trial assessment determined there was sufficient data to dismiss the hypothesis that the deep stops model was better than the Navy's current practice. Had the rates of dcs been similar between the two dive schedules then the trials would have continued.

The trial was halted because the conclusions were clear and there was no scientific justification to inflict more DCS on the deep stop group. Continuing the trial would have been unethical. Whether that was due to a planned mid trial assessment or an unplanned outcome doesnt really matter much

 

[elmo]

The trial was halted because the conclusions were clear and there was no scientific justification to inflict more DCS on the deep stop group. Continuing the trial would have been unethical. Whether that was due to a planned mid trial assessment or an unplanned outcome doesnt really matter much

I agree completely. I misinterpeted your previous post to imply that the study was incomplete and inconclusive because it was stopped early.

 

[Storker]

It was concluded after a mid-trial assessment

This may seem like a nitpick, but from a research ethics point of view it is not. The study was assessed continuously as data was obtained, and as soon as they had enough data to reject the hypothesis investigated ("Is the deep stop schedule better than the shallow stop schedule?") the experiment was stopped. So they designed the experiment in order not to bend one single diver more than necessary.

Ethical considerations require that a manned dive trial with DCS as an end point be designed to limit unnecessary injury to divers. Three hundred and seventy-five dives on each dive profile were planned, with sequential stopping rules to terminate testing of a schedule with a binomial PDCS higher than 7% at 95% confidence (reject-high) or lower than 3% at 95% confidence (reject-low). For safety reasons, testing of a particular dive profile could also be terminated if pre-defined, unacceptably severe DCS resulted. These rules were to limit exposure of divers to the risk of severe DCS and to limit the potentially inconclusive testing of two low-risk dive profiles.

¹ Doolette DJ, Gerth WA, Gault KA: "Redistribution of decompression stop time from shallow to deep stops increases incidence of decompression sickness in air decompression dives", NEDU Technical Report 11-06 (2011), p.4