Abstract
The McMurdo Research Station medical facility functions at the level of a rural community hospital emergency department. Telehealth technology has played an increasingly important role in providing intercontinental tertiary healthcare consultations, particularly for assistance with diagnostically challenging cases or cases involving complicated medical management. The role of telehealth in Antarctica is vital given the harsh and remote environment. The following case discusses a real-time tele-ultrasound consultation between the station physician and a patient with pericarditis at the McMurdo Medical Clinic in Antarctica and a team of cardiology consultants at the University of Texas Medical Branch, Galveston, TX. The use of teleheath technologies prevented an unnecessary intercontinental medical evacuation and allowed the patient to receive treatment at the McMurdo Research Station. This case report demonstrates that real-time tele-ultrasound can serve as an important diagnostic resource in the delivery of healthcare to isolated populations in remote environments.
Introduction
The United States Antarctic Program (USAP) operates and maintains three Antarctic research facilities: Palmer Station, on the Antarctic Peninsula; McMurdo Station, at the southern tip of Ross Island; and Scott–Amundsen South Pole Station, at the geographic South Pole.
McMurdo Station (77°51'S, 166°40'E) is the largest research station in Antarctica and the logistics hub for USAP operations supplying the South Pole Station. McMurdo is a coastal station made famous by Ernest Shackleton and Robert Falcon Scott as a launching point for expeditions to the South Pole. The mean annual temperature at McMurdo is −18°C. The summer population of scientists and support personnel may exceed 1,100, while the winter population ranges from 130 to 200. 1 The McMurdo medical facility functions at a level approximating that of a rural community hospital emergency department. It provides basic ambulatory care, limited inpatient care, and emergency services including advanced cardiac life support and advanced trauma life support. During the summer months, the clinic is staffed by two civilian physicians, a military flight surgeon, a physician assistant, a dentist, two nurses, an x-ray technician, a physical therapist, and a laboratory technician. Since the inception of the first teleradiology system in 1996, 2 the McMurdo telemedicine platform has been expanded and updated. During the 2000–2001 summer season, an Acuson Aspen ultrasound scanner expanded the teleradiology capabilities beyond plain film x-ray. An industry standard PolyCom teleconferencing system was added at the close of the 2001–2002 season to enhance real-time telemedicine capabilities. 3 Telemedicine technology has played an increasingly important role in providing intercontinental tertiary healthcare consultations, particularly for assistance with diagnostically challenging cases or cases involving complicated medical management. The role of telemedicine in healthcare delivery to the Antarctic is vital because intercontinental aeromedical evacuation during the summer season from McMurdo may have significant operational impacts and is weather dependent. The flight from McMurdo to the nearest tertiary-care center in Christchurch, New Zealand, a distance of 3,800 km, may take up to 8 h in optimal weather conditions.
This case report is not the first instance that a real-time, tele-ultrasound consultation has successfully assisted in the diagnosis of a serious illness at a USAP station. In April 2001, during the austral winter season at South Pole Station a real-time, tele-ultrasound consultation between the station's medical staff and physicians at Swedish Medical Center in Denver, CO, confirmed a case of gallstone pancreatitis. Subsequently, a historic winter medical evacuation ensued. 4 Other remote and isolated operational environments have adopted ultrasound as an important means of diagnosing and treating injury and illness. For example, ultrasound is the imaging modality of choice on board the International Space Station. 5,6
Case Report
During the austral summer season of 2002–2003, a 26-year-old man presented to the McMurdo Medical Clinic on December 2, 2002, with a chief complaint of pleuritic chest pain. His symptoms had begun the previous evening and had awoken him from sleep. His discomfort was so great that he was unable to get a restful night's sleep. He reported that he had sat up most of the night, which afforded some relief in contrast to lying supine. In addition, his discomfort was lessened with shallow breathing. He denied any exertional dyspnea, paroxysmal nocturnal dyspnea, orthopnea, or hemoptysis. Furthermore, he had no prior history of thromboembolic disease or lower leg trauma. There was no family history of respiratory, cardiac disease, or blood dyscrasias. The patient described a history of nephrolithiais and a history of nicotine addiction. He noted having contracted an upper respiratory infection 6 weeks prior to presentation. He was on no medications and denied any allergies. Physical examination revealed a young man in no acute distress. His vital signs were within normal limits: pulse oximetry of 97%, temperature of 97.9°F, heart rate of 85 beats/min, respiratory rate of 18 breaths/min, and blood pressure of 124/79 mm Hg, without pulsus paradoxus. Head and neck examination was normal. Examination of the chest revealed a normal-appearing thorax, no tenderness to palpation, and no crepitus, and the breath sounds were normal bilaterally. The patient did become uncomfortable with deep inspiration. No palpable thrills were appreciated on cardiac examination, jugulovenous pulsations were 3 cm above the sternal angle, and auscultation revealed first and second heart sounds of normal intensity, no extra heart sounds, and no pericardial friction ribs or bruits. Peripheral pulses were present and equal bilaterally. The abdominal examination was within normal limits. Examination of the musculoskeletal system revealed no apparent injury and no discoloration or swelling of the lower limbs. Prior to investigations the differential diagnosis included spontaneous pneumothorax, peptic ulcer disease, pericarditis, pulmonary embolus, and upper respiratory infection. Initial laboratory analysis revealed a normal complete blood count and differential and a normal erythrocyte sedimentation rate. The electrocardiogram showed a sinus rhythm of 85 beats/min, a rightward QRS axis at 93°, normal PR interval, peaked T waves in leads V2–V6, and 1 mm of ST elevation in leads II, aVL, and V2–V6.
A previous electrocardiogram from July 19, 2001, showed signs of benign early repolarization; however, the ST segments and T waves were less prominent than the current electrocardiogram. Of significant interest was the comparison of his current anteroposterior chest x-ray with a study taken only 10 months previously when the patient presented with a suspected rib fracture. A significantly enlarged cardiac silhouette was immediately apparent when comparing the two film series.
The cardiothoracic ratio from the most recent plain film was 0.54, whereas the cardiothoracic ratio 10 months previously was 0.47. A tentative diagnosis of pericarditis with possible pericardial effusion was established. An echocardiogram was arranged for the following morning. It is interesting that, upon returning to the clinic the next day, the patient appeared unwell. He described feeling “achy” and reported persistent retrosternal chest pain with deep inspiration that was worse with exertion. He reported alternating periods of fever and chills. He denied cough and reported no presyncope or syncopal episodes. Of note is that he was tachycardic at rest, with a heart rate of 104–108 beats/min. His remaining vital signs were unchanged from the previous day; however, the patient's repeat laboratory work-up revealed several alterations. The erythrocyte sedimentation rate was elevated at 17 mm/h, compared with 4 mm/h from the day before. In addition, the white blood cell count had risen to 14.0×109/L, neutrophils were elevated at 10.3×109/L from 8.6×109/L, monocytes and lymphocytes were 3.7×109/L, and platelets were 255×109/L. Electrolytes and liver function tests were normal, and creatine kinase was normal at 63 μmol/L. Given the working diagnosis, the patient was started on indomethacin 50 mg orally four times per day, a standard regimen for pericarditis. 7
Telemedicine
A teleradiology link for plain film interpretation has been in service at McMurdo Station since 1996, while an Acuson Aspen ultrasound unit was delivered to the station in February 2001. 8 Given the chest x-ray findings, the patient's resting tachycardia, and overall clinical picture, pericardial effusion and a potential cardiac tamponade were suspected. Using the Acuson ultrasound unit an echocardiogram was performed by one of the station's physicians who had basic ultrasound skills. Four cardiac views were recorded: subxiphoid, parasternal long axis, parasternal short axis, and an apical view. A 1-cm circumferential pericardial effusion was evident on the apical view.
For ultrasound store-and-forward interpretation, the still images were recorded in a DICOM format and stored on the Acuson's internal hard drive. While the Acuson ultrasound unit was connected to the medical virtual area network, the patient's file was transferred from the ultrasound unit to the TeleRad workstation and imported into the DICOM-compatible eFilm software program. The patient's echocardiogram file was then transmitted via McMurdo's T-1 satellite communications link to the general radiology reading room at Presbyterian Saint Luke's Hospital in Denver. A standard radiology report was generated once the attending radiologist read the images. The report was then returned by e-mail to a medical account at McMurdo Station, accessible by the station's medical staff. In this particular case, the report indicated a “small pericardial effusion, approximately 1 m in thickness,” thus confirming the initial diagnosis and McMurdo echocardiogram interpretation.
To determine the level of functional impairment the effusion was producing, a video-teleconference and real-time tele-echocardiography consult session was arranged with cardiologists at the USAP's tertiary referral center, the University of Texas Medical Branch (UTMB) in Galveston, TX. The UTMB Telemedicine Center is one of the world's leaders in telemedicine consultations, conducting over 5,000 telemedicine consults per month, and was contracted in 2002 to provide specialty telehealth services to the three USAP research stations in Antarctica. 9 Prior to the teleconsultation, the case summary, electrocardiograms, chest x-rays, and ultrasound images were forwarded via e-mail to the consulting cardiologist for review. Four days after the initial presentation, the patient, physician examiner, and other medical staff were assembled in the telemedicine room at McMurdo Station Medical Clinic, while the cardiology team viewed the remote examination from the Emergency Telemedicine Suite at UTMB. A PolyCom View Station FX videoconferencing system supports McMurdo's video-teleconferencing requirements. The Acuson ultrasound scanner was connected via an S-video input to the PolyCom View Station to support live transmission of the patient's echocardiogram images. The PolyCom camera also transmitted video of the McMurdo physician scanning the patient. The ultrasound transmission and video feed exited the medical hub via a dedicated data link of 384 kilobits per second (Kbps) to the McMurdo Station local area network (LAN). The ultrasound transmission accounted for two-thirds of the data link, while the additional video feed was allocated the remaining 128 Kbps. A previous study examining real-time, tele-ultrasound found that transmission at 256 Kbps provided adequate diagnostic quality imaging, with no significant differences in image interpretation when compared with a bandwidth of 386 Kbps. 10 From the McMurdo LAN the data were transferred to McMurdo's packeteer/router, over the station's T-1 line, and via a microwave link to the Black Island ground station. The data were then transmitted via a Ku microwave link to the INTELSAT 804 satellite, McMurdo Station's communication satellite. The data were received by a ground station at the Brewster Satellite Center in Washington, DC, and then transferred to a forward packeteer inside the Raytheon Polar Services (Centennial, CO) firewall. Once inside the RPSC LAN in Denver, the data entered the video-teleconferencing gateway and were directed to the Public Service Telephone Network and then on to UTMB via a 384 Kbps ISDN link.
The split-screen TV display allowed interaction with the consulting cardiology team in addition to visualization of the transmitted echocardiogram images. With the patient in the supine position, the physician examiner obtained the subxiphiod, parasternal short axis, and parasternal long axis views. Combining the echocardiogram images with the examination room video feed provided the cardiology team with direct visual feedback. As a result, the cardiology team was able to coach the physician operator to position the ultrasound probe in locations that would provide the best image acquisition. In this manner, normal left and right ventricular systolic function was demonstrated. In addition, no echocardiographic evidence of cardiac tamponade was found. Specifically, there was no right atrial free wall collapse by pulsed-wave Doppler and no significant respiratory variation in tricuspid or mitral inflow velocities. A residual pericardial effusion remained, and it was noted by the chief cardiologist that significant resolution had occurred since the initial static views were obtained. Therefore, there was little concern that a tamponade effect was being exerted by the effusion.
This real-time, tele-echocardiogram session was beneficial in providing a definitive diagnosis and in aiding patient management with real-time confirmation of the diagnosis by a team of cardiology consultants. In addition, this case demonstrated the ability to transmit two-dimensional, pulsed-wave Doppler, and color Doppler images in real-time to the cardiology team, who confirmed normal ventricular systolic function without echocardiographic evidence of cardiac tamponade. These findings established that the patient had not gone on to develop cardiac tamponade. In fact, the tele-ultrasound examination revealed that the effusion had begun to resolve when compared with the initial store-and-forward echocardiogram, performed 3 days previously. Furthermore, the cardiology team also validated the initial 7-day treatment with indomethacin, with a minor readjustment in the dose from 50 mg four times daily to three times per day. This importance of this case is underscored by a similar one that occurred during the preceding summer season when the tele-echocardiography system was not fully operational. In that instance, a 33-year-old man with a tentative diagnosis of pericarditis, which could not be confirmed conclusively, was evacuated from McMurdo Station for further investigation in Christchurch. 3 The real-time, tele-echocardiogram session described in this case report provided the McMurdo medical team with additional confidence in their ability to remotely manage potentially serious medical conditions when otherwise isolated from tertiary-care centers. The patient received timely specialist consultation that would have been delayed for several days had tele-echocardiography not been available. A definitive diagnosis was made with a favorable prognosis, which allowed the patient to remain in Antarctica and complete his summer tour. Consequently, a costly intercontinental aeromedical evacuation was avoided that would have significantly impacted operational activity at the Station.
In conclusion, this case report demonstrates that real-time tele-ultrasound can serve as an important diagnostic resource in the delivery of healthcare to isolated populations in remote environments.
Footnotes
Acknowledgments
The authors wish to thank Dr. Andrew Mackie, Program Director of the Pediatric Cardiology Residency Training Program, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada, for his constructive comments and advice on this manuscript.
Disclosure Statement
No competing financial interests exist.