Long-distance fixed-wing transport of obstetrical patients.

Objectives: Aeromedical obstetrical transports are mostly performed utilizing helicopters. The program here reviewed performs mostly fixed-wing transports. The purpose of the current study is to review our fixed-wing transfers and identify the complications encountered.

Methods: A retrospective review was conducted of the fixed-wing obstetrical air transports performed by the StatCare aeromedical transport service from July 1, 2000 through June 30, 2002. Information on each patient (age, gestational age, gravida status, diagnosis, preflight physical examination) was collected using a data sheet. Also noted were any described complications.

Results: During the 24-month study period, 80 fixed-wing transports were performed. In-flight complications included nausea and vomiting (80%), increased contractions (8.8%), hypertension (1.3%), hypotension (1.3%), decreased maternal respiratory drive (1.3%), and infiltrated intravenous line (1.3%).

Conclusions: The complications encountered during long-distance fixed-wing aeromedical transport of obstetrical patients include nausea and vomiting, increased contractions, hypertension, hypotension, decreased maternal respiratory drive, and an infiltrated intravenous line.

Key Words: air ambulance, female, obstetrics, patient transportation safety

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Aeromedical transport of critically ill patients enjoys widespread use throughout the United States today. The benefits of transport have been extended to include obstetrical patients, who are now being transported by air with increasing frequency to tertiary care facilities. It has been demonstrated that fetal outcome is more favorable with transport of the mother to a tertiary care center before delivery. (1) Furthermore, several investigators have previously demonstrated that air transport of obstetrical patients can be accomplished with minimal risk to the patient and her baby. (2) Speed of transport and the clinical competency of the transport team are often cited as reasons that air is favored over ground transport. (3) Most of these aeromedical transports are performed with helicopters. (1) While studies have reported the most feared in-flight complication, in-flight delivery, there is limited data on other complications likely to be encountered. (1) Most studies only report the obstetrical critical care diagnoses that were present (pregnancy-induced hypertension, eclampsia, etc). (1,3) Our aeromedical program transports mostly by fixed-wing air-craft over longer distances. The purpose of the current study was to review our experience with fixed-wing long-distance transfers with special attention to in-flight complications.

Materials and Methods

We retrospectively reviewed all obstetrical patients transported during a two-year period from July 1, 2000 through June 30, 2002. A computer search to identify obstetrical transports for this time period was performed, and only those charts identified by the computer search were reviewed. We excluded all helicopter transports and all postpartum transports.

StatCare is a not-for-profit air ambulance service based in Louisville, Kentucky. At the time of these transports, StatCare utilized a King Air 200 or a King Air 90 for fixed-wing transports. In addition to the pilot, the air medical team must meet specific minimum qualifications, and consist of at least two crew members, one of whom is a registered nurse. With rare exception, there is an obstetrical resident physician on board. Crew members must hold certification in basic life support, advanced cardiac life support, pediatric advanced life support, and the neonatal resuscitation program. All flight nurses have completed a high-risk maternal transport course and worked clinical hours in an obstetrical care area.

The initial transport request is received by the labor deck at one of two tertiary care centers and accepted by an attending obstetrician. Once the initial report is received by the attending and a decision to transport is made, the attending contacts the StatCare communications center. The transport obstetrical resident is contacted and the team is activated. If there is no obstetrical resident available, the medical director for StatCare and the obstetricians involved in the case decide if the transport should be done without a physician. The transport is documented on a prefabricated form by the flight nurse or paramedic, and includes a preflight assessment of the patient, interventions, and the in-flight course.

All charts were reviewed for the following data: age, estimated gestational age (EGA), gravida/parity status, presence of a physician on the flight, mode of transport, receiving facility, duration of transport, diagnosis, preflight examination (including cervical examination and presence/absence of contractions), in-flight complications/changes in examination, and in-flight interventions and outcomes of interventions. Transport time was defined as the time from when the patient left the transferring hospital until they arrived at the receiving hospital (this includes the two ambulance rides: one from the transferring hospital to the aircraft and one from the aircraft to the receiving hospital). We also calculated a total run time, defined as the time from initial request for service until the patient arrived at her destination. The study was approved by the Human Studies Committee.

Results

A total of 98 obstetrical transports were identified by the computerized search of all StatCare runs for the given timeframe. There was one additional case in which the crew responded to the transferring hospital; however, delivery was imminent and the patient was not transported. Of the 98 transports, 18 were excluded (15 helicopter transports and 3 post-partum transports). The remaining 80 fixed-wing transfers were reviewed. The patients transported ranged in age from 17 to 41 years old, with the mean age being 25.3 years (median 23.5, mode 20). The EGA ranged from 22 weeks to 36.6 weeks, with the mean being 25.5 weeks (median 31, mode 33). Gravida status and parity were recorded on 51 patients. These patients ranged from a minimum of gravida 1 to a maximum of gravida 10. Thirty-nine were multigravida. The other 12 were primigravida. A physician was present on all of the flights. The physicians were obstetrical residents from the University of Louisville obstetrical residency program. There were a total of eight transferring hospitals. The distances from the receiving hospitals ranged from 82 to 209 nautical miles. The mean distance was 178 nautical miles (median 178, mode 178). The receiving facility was University of Louisville Hospital in 37 cases. Norton Hospital received the other 43. Both hospitals were affiliated with the local obstetrical residency training program, provided high-risk obstetrical staffing, and had neonatal intensive care capabilities. The duration of transport was calculated from the 76 transports with sufficient documentation to make such a calculation possible. The mean transport time was 92 minutes (median 96 min, mode 92 min, range 67 to 140 min). The mean total run time was 249 minutes (median 244.5 min, mode 228 min, range 181 to 379 min). Reasons for transportation to the tertiary care hospitals included: preterm labor (PTL) 33 (41.3%); preterm premature rupture of membranes (PPROM) 17 (21.3%); preeclampsia 17 (21.3%); both PPROM and PTL 6 (7.5%); and other 7 (8.8%). These data are summarized in Table 1.

Thirteen of these patients were pregnant with twins. One patient was pregnant with quadruplets. The results of the preflight cervical examination were not documented in 21 cases. In those cases where the examination was documented, there were five patients who had a cervix dilated to 5 cm, eight patients dilated 4 cm, and the remaining 46 patients who were dilated less than 4 cm. Thirty-seven patients were actively contracting before transport. Of these 37, 30 were labeled as "mild," "rare," "intermittent," "occasional," "slight," or were greater than five minutes apart. The other seven were contracting every 5 minutes or less. Forty-three were not having contractions.

Sixty-four patients were started on magnesium drips for tocolysis before lift-off. Of these 64, five drips were increased and one was discontinued in flight. One magnesium drip was actually initiated in flight. Twenty-one patients had documented contractions in flight. Seven of these had increased contractions in flight. Six were treated with magnesium and one was treated with terbutaline because she refused magnesium. Twenty-two complications occurred in-flight, including the aforementioned seven patients with increased contractions (Table 2). Fourteen patients developed nausea and/or vomiting; all received phenergan. In addition, there was one patient each with the following: intravenous (IV) line infiltrated, hypertension (responded to hydralazine), hypotension (resolved with IV fluids and left lateral decubitus positioning), and decreased respiratory drive (resolved with discontinuation of the magnesium drip). No deliveries occurred while in flight.

Discussion

The use of aeromedical transport for obstetrical patients has increased dramatically in the last 10 years. Previous studies have indicated that both mother and baby do well during these transports. (2,4,1,5) However, none of these studies reported on in-flight complications with the exception of in-flight delivery. Most of the transports are done by helicopter over a short distance. (1) We transport over longer distances than many programs, and have a high utilization of fixed-wing aircraft. In our series, all patients were transported safely with a few minor complications. The reason for transport was most commonly preterm labor followed by premature rupture of membranes. Preeclampsia and other critical care diagnoses including hemorrhage or trauma accounted for 26.2% of our patients. These numbers are similar to those seen in the large series from Samaritan AirEvac in Phoenix, Arizona, in which a critical care diagnosis accounted for 23.4% of all maternal transports performed during their 14-month study period. (4)

The greatest concern among aeromedical programs, with regard to high-risk obstetrical transport, is the possibility of in-flight delivery, according to a national survey published in 2001. (6) However, previous studies have shown that in-flight delivery is uncommon. (1,5) There was only one patient during the two-year period here studied that was felt to be at risk for in-flight delivery. That patient was not transported, and delivered before the crew returned to base.

Our study is unique in several respects. First, we report a large series of fixed-wing transports over long distances. Second, we report on the actual in-flight complications. Twenty-one patients had contractions during flight, and seven had increased contractions that were treated with magnesium or terbutaline. Other documented complications seen in our study included: nausea and vomiting, infiltrated IV, decreased respiratory drive, hypertension, and hypotension. All complications were managed without problems.

Very few aeromedical programs still utilize a physician as a member of the flight crew. We are unaware of any other program that routinely utilizes an obstetrical resident as a member of the flight crew. It cannot be determined from a retrospective review whether the presence of a physician has any impact on the management of these complications. However, most complications were minor, and most likely did not require the presence of a physician.

One recent study found that many aeromedical programs were poorly prepared for high-risk obstetrical transport. (6) Sixteen percent of the programs did not even carry tocolytics. We found increased contractions to be a common in-flight complication. Flight crews must be trained to deal with increased contraction, and must carry appropriate medications.

Our study is somewhat limited by the fact that it is a retrospective review. Some complications may not have been documented. Another limitation of this review is that patient outcomes were not examined. It might have been helpful to learn which patients delivered immediately upon arrival and which patients were eventually discharged without delivery. This study is also limited by its size. A larger study might find additional or more serious complications.

The issue of ground transportation of these patients is very complex and cannot be addressed by the present study. Some of these patients could probably have been managed safely using ground transportation. However, many rural EMS services may not have the training and experience to safely transport these patients over long distances. There is also the issue of taking an EMS crew and vehicle out of the local community for eight or more hours.

Conclusions

We reviewed the fixed-wing air transport of obstetrical patients over a two-year period and found that there were only a few complications and no in-flight deliveries. In-flight complications included nausea and vomiting, increased contractions, hypotension, hypertension, decreased maternal respiratory drive, and an infiltrated IV. Flight crews must be trained to deal with these complications.

Table 1. Reason for transfer/diagnosis

Diagnosis                                             No.

Preterm labor (PTL)                                   33
Preterm premature rupture of membranes (PPROM)        17
Preeclampsia                                          17
PPROM and PTL                                          6
Vaginal bleeding                                       3
Intrauterine growth retardation                        2
Fetal bradycardia                                      1
Trauma (fractured pelvis)                              1

Table 2. In-flight complications

In-flight complication                          No.

Nausea and/or vomiting                          14
Increased contractions                           7
Hypertension                                     1
Hypotension                                      1
Decreased maternal respiratory drive             1
Infiltrated IV                                   1

Accepted February 6, 2004.

References

1. Low RB, Martin D, Brown C. Emergency air transport of pregnant patients: the national experience. J Emerg Med 1988;41-48.

2. Connor SB, Lyons TJ. US Air Force aeromedical evacuation of obstetric patients in Europe. Aviat Space Environ Med 1995;1090-1093.

3. Elliott JP, Foley MR, Young L, et al. Air transport of obstetric critical care patients to tertiary centers. J Reprod Med 1996;171-174.

4. Elliott JP, Foley MR, Young L, et al. Air transport of obstetric critical care patients to tertiary centers. J Reprod Med 1996;171-174.

5. Van Hook JW, Leicht TG, Van Hook CL, et al. Aeromedical transfer of preterm labor patients. Tex Med 1998;88-90.

6. Jones AE, Summers RL, Deschamp C, et al. A national survey of the air medical transport of high-risk obstetric patients. Air Med J 2001;17-20.

RELATED ARTICLE: Key Points

* The aeromedical transport service StatCare performs a large number of long-distance fixed-wing transports of obstetrical patients.

* Although these were long-distance transports there were no in-flight deliveries.

* In-flight complications during these fixed-wing obstetrical transports were minor and included; nausea and vomiting, increased contractions, hypertension, hypotension, decreased maternal respiratory drive, and an infiltrated intravenous line.

* Although StatCare utilizes physicians on almost all flights, the complications during these transports were minor, and the necessity of physician attendance is not clear.

Daniel J. O'Brien, MD, Edmond A. Hooker, MD, Jodie Hignite, NP, and Eric Maughan, MD

From the Department of Emergency Medicine, University of Louisville, School of Medicine, and StatCare, Louisville, KY.

This study was approved by the Human Studies Committee of the University of Louisville

Reprint requests to Edmond A. Hooker, MD, Department of Emergency Medicine, University of Louisville, School of Medicine, 530 South Jackson Street, Room C1H17, Louisville, KY 40202. Email: [e-mail]