Emergent time

TABLE 60-1. Ophthalmic Emergencies Time to Follow-up by Ophthalmologist1... 

Concentrations at 700,000 and 800,000 ppm for 3 to 5 h induced deep anesthesia in dogs, usually within 1 min (Shulman and Sadove 1967). Respirations remained spontaneous, and blood pressure remained normal. Light anesthesia was induced at concentrations of 500,000 to 600,000 ppm. Emergence time was usually less than 2 min. 

No doubt a great many other significant publications could have been found which would have led to a further expansion of the manual. However, rather than to strive for perfection it was considered more important to bring the manual to completion and to publish it now. In the present emergency, time is of paramount importance, and the author hopes that this book will not only be a time-saver but that it will be of service generally to the professional men who are concerned with explosives and particularly to the thousands of new workers who are entering this field. 

Several small clinical trials have suggested that total intravenous anesthesia with propofol reduces the incidence of postoperative nausea and vomiting and results in shorter emergence times. However, a systematic review (52) and a meta-analysis (53) have shown that most studies were small, did not have follow-up for more than 6 hours postoperatively, and were sponsored by industry. The results were difficult to combine, owing to heterogeneous definitions of postoperative nausea and vomiting. 

There are five to seven kinds of nitrosamines normally present in tobacco smoke condensate. The internal standard is a nitrosamine that does not occur in tobacco or its smoke, but is used to confirm the emergence time and quantify the amounts of the nitrosamines in the samples. The curious effect of the additive is that one of these peaks, corresponding to a particularly toxic cancer-causing nitrosamine called NNK, decreases in size, roughly in proportion to the amount of additive in the cigarette. An increase in the size of a peak corresponding to a less cancerous nitrosamine called NAT is also observed. This is a promising result. Could it be an additive that improves the flavor of the product and makes it less harmful ... 

A week later, a very depressed Joe is back from his vacation ( Viva Lost Wages, as the saying goes). Tom decides to give him some space for a while. Meanwhile, Sue has come up with three or four possible identities for the new chemical, and two can be easily synthesized. A third possibility may be that the same chemical has an impurity or side product that occurs in small amounts in tl e synthesis of NNK but gets removed in purification. Tom injects a solution containing only purified NAT and the unpurified NNK in a capillary column and finds that one impurity in the NAT solution has the same emergence time as the mystery chemical. 

Exact emergence times in gas chromatography are strong but not conclusive confirmation of the identity of a compound. Should Tom wait until he has tested the other possibilities before informing Joe about his findings ... 

Tom has decided to wait before telling Joe, so he tests the other possible chemicals. None of them have the same emergence time he concludes that the mystery chemical is most likely the same as the impurity from the laboratory synthesis of NNK. Sue has recently characterized this to be the nitrosamine NNAL. It does not normally occur in tobacco or tobacco smoke, and its properties have not been studied. 

In rats administered isoflurane alone (5%), isoflurane plus valerian (30 mg/kg), isoflurane plus midazolam (2 mg/ kg), or isoflurane plus valerian (30 mg/kg) and midazolam (2 mg/kg), no significant differences in emergence time from anesthesia were observed in the isoflurane plus valerian... 

How long do you want in terms of emergency time covered ... 

Collection of data and the development of models to enable rapid, high-confidence determination of how a limited supply of a chemical should be distributed to minimize consequences. Building and executing an effective simulation with all the appropriate feed data might not be feasible on an emergency time line. 

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