(CNN) Before Hurricane Maria made landfall in Puerto Rico on September 20, the United States had already experienced intermittent shortages of IV bags, which are used to administer and dilute medications. The devastation caused by the Category 4 hurricane -- the first to hit the island in more than eight decades -- amplified the IV bag shortage, in particular sodium chloride 0.9% injection bags, which are ubiquitous in medical facilities and hospitals.

Puerto Rico, which produces more pharmaceuticals by dollar valuefor the nation than any of the individual 50 states or any foreign country, has been key to the supply of these IV saline bags.

Since early November , the US Food and Drug Administration has issued updates and guidance to hospitals and medical facilities.

On Tuesday, Dr. Scott Gottlieb, the FDA commissioner, said in a statement the agency continues "to expect that the shortage of IV fluids will improve in the coming weeks and months."

Measures taken by the FDA include working with manufacturers to import product into the US "from their foreign facilities," said Gottlieb.

The FDA has already approved IV saline products from Fresenius Kabi, a global healthcare company headquartered in Germany, and Laboratorios Grifols, a separate global health care company based in Spain. This "is expected to result in increasing product supply in U.S. market in the next several weeks," said Gottlieb. He added that the agency is looking at "additional potential import sites" as well.

The FDA is considering a way to extend existing supplies in hospitals. "If expiration dates can be safety extended, it would allow some near-expiry product that remains at the hospital level to be used," said Gottlieb.

"Despite these steps, it may still take more time for new product supply to diffuse across the marketplace and have a noticeable impact on product availability," he said.

In a previous statement on January 4 , Gottlieb noted that Baxter International Inc., "a leading producer of IV saline fluids," had reported their Puerto Rican facilities had returned "to the commercial power grid" on the island before the holidays.

post on the company's website noted that overall industry capacity, as well as "an aggressive flu season," had "diminished" the supply of small volume bags, which are manufactured in Puerto Rico and mainly used in pharmacies.

Bill Rader, a spokesman for Baxter, said the FDA had granted the company "special regulatory discretion" and allowed the company to import products normally made in Puerto Rico from its global facilities for the US market. Temporarily, then, Baxter has been shipping IV bags from Ireland, Australia, Canada, Mexico, England, Italy and Brazil to hundreds of US hospitals since late October.

Mexico's (and others') gain

Larger volume solution IV bags, including 500 ml and 1000 ml bags, are not manufactured in Puerto Rico, so the hurricane did not interrupt their production, noted Rader. "We continue making these and we're bringing additional units of large volume solutions courtesy of a permanent approval granted by FDA." This permanent agency approval will directly benefit one of Baxter's plants in Mexico, according to Rader.

Necessarily, the FDA also has been in "frequent communication" with hospitals, medical centers and other organizations with guidance about conservation efforts to mitigate the shortage, Gottlieb added. To that end, the FDA posted a fact sheet compiled by American Society of Health-System Pharmacists and the University of Utah Drug Information Service that explained the situation and offered recommendations for care providers and pharmacies on the safety and conservation of the IV bags.

Other groups, including the American Hospital Association, believe addressing the shortage requires a more comprehensive strategy.

Hospitals feel the pain

In November, the association posted a letter on "the shortages of critical pharmaceuticals ," appealing to lawmakers who sit on the Oversight and Investigations Subcommittee of the House Energy and Commerce Committee.

"Recent natural disasters, most notably Hurricane Maria, have heavily compromised pharmaceutical manufacturing in Puerto Rico and now leave the US health care system on the brink of a significant public health crisis," wrote the association and others, including the American Society of Health-System Pharmacists.

Intermittent shortages of the IV bags, already a problem due to a limited number of suppliers and less than optimal manufacturing capacity, "are emerging as a serious problem for hospitals, health care systems, and ambulatory care infusion centers," the authors of the letter wrote. "Hospitals and other health care settings have reported that they are running critically low on product and are unclear as to when their supplies will be replenished."

Courtney Burke, Chief Operating Officer for the Healthcare Association of New York State, agrees with this assessment.

"We noticed an uptick in calls from some of our hospitals last week concerned about how things were going," said Burke. "The problem is that the flu season has come a little early, a little bit earlier than normal." This has increased demand for IV bags, she noted.

"We were anticipating that there would be an uptick in supplies in mid- to late-January and everybody was trying to manage to that time frame," said Burke. "We're at that critical point right now. We're hoping to see that increase in supply very soon."

She said the hospitals in New York have been managing "fairly well for several months." They've been using the FDA recommended techniques, including using oral medications when possible, injecting drugs directly and even resorting to glass bottles, said Burke, whose association has been helping individual hospitals "figure out how to manage it."

Mark Ross, emergency preparedness southeastern regional manager for The Hospital and Healthsystem Association of Pennsylvania (HAP), said that across the state "we are handling the situation very well."

"A day does not go by where we do not speak to a hospital or health system," said Ross. "We do status checks on the facilities across the state on a regular basis to get the pulse."

"Going back to 2014" or so is when the hospitals first started seeing these shortages, Ross recalled. "We do exercises and drills around critical supply shortages for all our hospitals and health systems across the state ... so all the exercises, drills and education that we've done have really paid off for us now."

"Every patient, every flu patient, every hospital is a little different, but we are holding our own with conservation and alternative methods so we can administer the right care for the right patient at the right time," said Ross.

In constant touch with others across the nation, he can see trends emerge and prepare in advance "when we see what is taking place," he said.

Asked if other states have had "difficulties," he said, "difficulty is probably not a word I would use. Everyone is handling it in their own right and in their own ways." That said, information has been widely shared among the states.

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Burke noted that their recent webinar on best practices for managing a short supply of IV bags has been "the most viewed" they've had in several months.

"Supposedly folks from other states have been viewing it as well," she said. "Hospitals are fairly well-versed at dealing with a wide variety of challenges and so they have a lot of excellent people on the ground who are helping them manage the situation."

Given recent improvements on the ground, Gottlieb noted that he's "optimistic" supplies will increase over the next few weeks, "even if the shortages will not be fully resolved immediately. That said, the production situation in Puerto Rico remains fragile."