With the physical footprint of American hospitals growing ever larger, the risk for patients developing hypoxia during transport from the operating room (OR) to the PACU is real. Recently, researchers found that nearly 7% of patients will develop hypoxia en route, prompting them to recommend the availability of portable pulse oximetry and supplemental oxygen in these circumstances.
“As we all know, postoperative hypoxia is a life-threatening complication, the consequences of which can be devastating for the patient,” said Olga Eydlin, MD, a staff anesthesiologist at New York University Langone Medical Center, in New York City. “While monitoring pulse oximetry is standard of care in the operating room and the recovery room, there’s no consensus regarding what to do with patients when they’re being transported.
“In large hospitals, transport from the operating room to the PACU can be quite lengthy, resulting in the patient having inadequate oxygenation for an unacceptable period of time,” she continued. “At our institution, we sought to improve our patient safety during transport and minimize incidents of hypoxia on arrival to the PACU.”
Values Checked in OR, PACU and in Transit
To better define these incidents, the researchers analyzed data from 3,440 patients who received an anesthetic for a procedure or surgery at the institution between September 2015 and March 2016. Each patient was monitored with a pulse oximeter during transport to the PACU. Values of blood oxygen saturation (SpO2) were recorded before leaving the OR, during transport and upon arrival at the PACU.
For purposes of the study, mild hypoxia was defined as SpO2 more than 90% to 94%, moderate hypoxia as SpO2 75% to 90% and severe hypoxia as SpO2 less than 75%. Each case was examined according to a variety of criteria, including experience level of the transporter, American Society of Anesthesiologists (ASA) physical status, type of anesthetic, extremes of age, and the presence of comorbidities such as obstructive sleep apnea, smoking, body mass index (BMI) over 30 kg/m2, and cardiac or pulmonary disease. The investigators also evaluated whether the patient was intubated/spontaneously breathing room air versus using supplemental oxygen.
As Dr. Eydlin reported at the 2016 annual meeting of the ASA (abstract A1105), 223 cases of mild hypoxia (6.5%) were observed, along with seven cases of moderate hypoxia (0.2%) and one case of severe hypoxia (0.03%). Of the patients with mild hypoxia, 44 were transported with supplemental oxygen, 171 were transferred breathing room air and eight were intubated. The overwhelming majority of patients (211) received general anesthesia, six received regional anesthesia and six received monitored anesthesia care.
All seven patients who developed moderate hypoxia received general anesthesia. Of these, there were no pediatric patients and two were older than 75 years. One had obstructive sleep apnea, one was a smoker, two were emergency cases, and four were ASA III or IV. Three of these patients were transported with supplemental oxygen, three were breathing room air and one was intubated. The one case of severe hypoxia occurred in an ASA II adult who had undergone general anesthesia and was intubated during transport.
“Looking at the type of anesthetic, there was a higher frequency of postoperative hypoxia in patients who received general anesthesia,” Dr. Eydlin reported. “When we looked at whether they received supplemental oxygen or not—and that decision was at the discretion of the anesthesia provider—we saw that patients transported on room air did, indeed, have a higher frequency of desaturations during transport.”
Not as Rare as Supposed
The researchers performed univariate and multivariate analyses of the various factors associated with desaturations during transport. The univariate analysis revealed that patients with cardiac or pulmonary disease had a significantly greater risk for developing hypoxia during transport.
“With multivariate analysis, we were able to identify that those patients with BMI greater than 30 [kg/m2] were at a statistically significantly increased risk of hypoxia during transport,” Dr. Eydlin said. Not surprisingly, obese patients who received supplemental oxygen were at less risk than their obese counterparts who did not.
These results, she concluded, demonstrate that hypoxia during transport may not be as rare as previously thought, “and, in fact, can be life-threatening. At our institution, it is now mandatory to transport everyone to the PACU with a portable pulse oximeter. They’re safe, they’re low-cost, they’re noninvasive and they’ve been introduced to improve patient safety.”
She suggested that other institutions consider employing similar technologies when transporting patients, as well as having supplemental oxygen available to the anesthesia provider during transport.
Session moderator Uday Jain, MD, PhD, questioned the utility and cost of portable pulse oximetry. “It is standard practice in many institutions to administer oxygen during transport to all general anesthesia patients,” said the staff anesthesiologist at Alameda Health System, in Oakland, Calif. “I’m curious, though: If you are administering oxygen and you detect a desaturation with the pulse oximeter, what will you do before reaching the PACU?”
“By no means are we suggesting that the pulse oximeter is replacing the anesthesia provider closely watching the patient,” Dr. Eydlin replied. “The pulse oximeter is just an additional modality to provide information to the anesthesia provider. It’s been shown in previous studies that the pulse oximeter will detect unrecognized desaturations faster than the clinician can.”
“With all the talk about costs these days, it’s important to remember that a portable pulse oximeter may not be a one-time cost,” Dr. Jain continued. “Some will break and some will get lost, so you’re substantially adding to the cost of care. And whether this is really necessary in the presence of supplemental oxygen administration is debatable. It should be ensured that the patients are ventilating adequately before leaving the OR.”
“There is certainly a cost involved,” Dr. Eydlin said. “But having a devastating consequence for the patient can potentially have a much higher cost, both in terms of the life of the patient and the financial cost. So we think it’s a very effective modality in that regard.”