There's little worse than being in an unfamiliar place when you're in need of medical assistance, or heck, even a bathroom. When you're in an unfamiliar place and you can't ask anyone for help, that urgency and frustration can be multiplied exponentially.
If you're going to a Spanish-speaking nation, and aren't fluent in the language, you should bring along a couple types of books: a Spanish-English dictionary and an English-Spanish phrase book. Many travelers automatically bring the dictionary, which will get you by in a pinch for the little things, like getting to a restroom on time. It doesn't take more than a worried look and the word “baño” to get you where you need to go. But, if the thought, feeling or need you're trying to express goes deeper than that, having a phrase book can really help a great deal.
Just as we have similar words that mean several different things in English, Spanish has its own little tricks and phraseology. The structures of sentences and phrases is different and when you're a guy or gal in need, you want as little room for error as possible.
I recommend checking out Dover Publications' Easy Spanish Phrase Book: Over 770 Basic Phrases for Everyday Use. It can help you find the right phrases for everything from travel to entertainment, and could very well be your best friend during your trip.