Anesth Analg 2003;96:1447-1452
© 2003 International Anesthesia Research Society
CRITICAL CARE AND TRAUMA
The Influence of Local Active Warming on Pain Relief of Patients with Cholelithiasis During Rescue Transport
Alexander Kober, MD*,
Thomas Scheck, MD*,
Freia Tschabitscher, MD*,
Stefanie Wiltschnig, MD*,
Sabine Sator-Katzenschlager, MD*,
Werner Madei, MD
,
Burkhard Gustorff, MD*, and
Klaus Hoerauf, MD*
*Department of Anesthesia and Intensive Care, University of Vienna; and
Department of Anesthesia, Armed Forces Medical Hospital, Amberg, Germany
Address correspondence and reprint requests to Klaus Hoerauf, MD, Department of Anesthesiology and Intensive Care, University Hospital of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. Address e-mail to klaus.hoerauf{at}univie.ac.at
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Abstract
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Upper abdominal pain, a frequent symptom of the presence of gallstone disease, is the cause of 6% of the emergency calls of the Austrian emergency system. Pain resulting from cholelithiasis is characteristically severe. Recent data show that active warming during emergency transport of trauma victims is effective in reducing pain. Therefore, we hypothesized that local active warming of the abdomen would be an effective pain treatment for patients with acute cholelithiasis and could be provided by paramedics. Sixty patients (>19 yr) consented to participate in this study. They were divided into two groups: Group 1, who received active warming of the upper abdomen with a carbon-fiber warming blanket (42°C), and Group 2, who received no warming of the abdomen. Neither group received any drug-based pain care. Patients were asked to rate their pain and anxiety by using visual analog scales (VAS). Statistical evaluation was performed with Student’s t-test; P < 0.05 was considered significant. In Group 1, a significant (P < 0.01) pain reduction was recorded in all cases on a visual analog scale (VAS), from 86.8 ± 5.5 mm to 41.2 ± 16.2 mm. In Group 2, the patients’ pain scores remained comparable, from 88.3 ± 9.9 mm to 88.1 ± 10.0 mm on a VAS. In comparing Group 1 with Group 2 on arrival at the hospital, pain scores showed a significant difference (P < 0.01). In Group 1, the VAS score changes for anxiety were significantly reduced (P < 0.01), from 82.7 ± 10.8 mm before treatment to 39.0 ± 14.0 mm after treatment. In Group 2, a nonsignificant change of this score was noted, from 84.5 ± 14.6 mm to 83.5 ± 8.4 mm. Comparing Group 1 with Group 2 on arrival at the hospital showed a significant difference in anxiety scores (P < 0.01). We conclude that local active warming is an effective and easy-to-learn treatment for pain resulting from acute cholelithiasis in emergency care.
IMPLICATIONS: Active local warming of the upper abdomen is an effective treatment for patients with cholelithiasis being transported to the hospital by paramedics who are not permitted to provide any drug-based pain care. We observed no negative side effects of this treatment.
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Introduction
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Upper abdominal pain, a frequent symptom of the manifestation of gallstones, is the cause of 6% of the emergency calls of the Austrian emergency system, in accordance with published data (1–4). Pain from cholelithiasis is characteristically severe and is located in the epigastrium, the right upper quadrant, or both. The onset is relatively abrupt and often awakens the patient. The pain is steady in intensity, may radiate to the upper back, may be associated with nausea, and may last for hours to up to a day. Dyspeptic symptoms of indigestion, belching, bloating, abdominal discomfort, heartburn, and specific food intolerance are common in people with gallstones, but they are probably unrelated to the stones themselves and frequently persist after surgery. Many people with gallstones have a history of pain attacks. Those whose stones are symptomatic at discovery have a more severe course, with approximately 6%–10% experiencing recurrent symptoms each year and 2% experiencing biliary complications. The best predictors of future biliary pain are a history of pain at the time of diagnosis, female sex, and obesity. The risk of acute cholecystitis appears to be increased in those with large solitary stones, that of biliary pancreatitis in those with multiple small stones, and that of gallbladder cancer in those with large stones of any number (5).
Although there are several drug-based options for pain control, patients with nonlife-threatening illnesses are usually transported to the hospital by ambulance cars in the absence of an emergency physician (6,7). To reduce these unfavorable symptoms during transport in the absence of a physician, the availability of a noninvasive, nondrug-based therapy would be beneficial. On the basis of a MEDLINE/EMBASE literature search, there are no data available for a nondrug-based therapy for pain caused by gallstones during rescue transport to the hospital.
However, recent data show that active warming on emergency transport of trauma victims is an effective method of reducing minor trauma pain (8). Therefore, we hypothesized that local active warming of the abdomen would be an effective method of pain treatment to be performed by paramedics in charge of patients with acute cholelithiasis. Accordingly, we conducted a prospective, randomized, blinded study to test the hypothesis that local warming in patients with cholelithiasis in the prehospital setting decreases pain. We also predicted that the warming treatment would reduce anxiety and sympathetic hyperactivity and increase patient satisfaction.
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Methods
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After approval from our Institutional Ethics Committee, 86 patients (>19 yr) consented to participate in this study. The Austrian Red Cross is divided into two parallel rescue systems. Minor trauma and illnesses are handled by paramedics who are not permitted to give either drugs or fluids. In this study, all our patients were transported by paramedics and were likely to have cholelithiasis. Because the precise diagnosis by means of ultrasound or computed tomography (CT) could not be established in the prehospital setting, we defined three entry criteria for our patients: - Positive medical history of gallbladder stones.
- Acute upper abdominal pain comparable to the patient’s last episode of pain during hospitalization for cholelithiasis.
- Pain >60 mm on a visual analog scale (VAS; 0 mm, no pain; 100 mm, most intense pain imaginable).
Patients were excluded in the case of cognitive impairment or inability to easily communicate with the paramedics. One day after the study day, a final diagnosis based on radiography, ultrasound, or CT scan was requested from the hospital. Patients experiencing pain for reasons other than cholelithiasis were excluded from the final data analysis.
At the emergency site, an investigator determined whether the patient was suitable for this study and obtained verbal and written documented consent for participation. Patients in both groups were covered on the abdomen with a carbon-fiber electric heating blanket (ThermaMed GmbH, Bad Oeynhausen, Germany) that was itself covered by a single wool blanket. The entire cover measured 80 x 200 cm, with the actively heated section being 40 x 148 cm. Resistive heating was provided by passing a 7- to 8-A current through the carbon fiber. Batteries provided sufficient heating for up to 40 min.
Patients were randomly assigned to two groups: resistive heating (Group 1) or passive warming (Group 2). Randomization was based on computer-generated codes that were sealed in sequentially numbered opaque envelopes. The blankets were set to 42°C for the patients assigned to active warming. In contrast, the blanket electrical system was not activated for patients assigned to passive warming. The electrical system was set by an unblinded investigator on the basis of the randomization. The investigator subsequently locked the control unit in a metal box for blinding. Once positioned, the covers were left in place until the patients arrived at the hospital. The designated treatment was initiated at the emergency site even before the patients were transferred to the ambulance.
Patients were monitored with a tympanic thermocouple (core temperature), skin thermosensors on the right upper abdominal skin, and intracutaneous thermosensors in the right upper abdominal skin at a 4-mm depth. Additionally, skin sensors were placed on the forearm and on the finger to receive data of indirect signs of vasodilatation (finger warmer than forearm) or vasoconstriction (forearm warmer than finger) (9). All sensors were commercially available from Mallinckrodt Anesthesiology Products, Inc. (St. Louis, MO) and had an accuracy and precision of near 0.1°C.
Patients then were transported to the hospital, and the duration of the transport was recorded. Because the cases were nonurgent, the patient’s choice of hospital was taken into consideration; consequently, they were not necessarily taken to the nearest facility.
Morphometric characteristics were recorded. Measurements were performed immediately after entering the ambulance and again on arrival at the destination hospital. All measurements were recorded by the same independent investigator, who was blinded to the treatment with the carbon-fiber blanket electrical system. He was not permitted to touch either the patient or the blanket. He did talk with the patient during the rescue transport but was not allowed to comment on the temperature of the blanket.
In addition to the temperature monitoring, measurements included oscillometric blood pressure and heart rate. The patient was asked to rate his or her pain and anxiety by using VAS scores (0–100 mm; see above). Air temperature was recorded by a thermocouple positioned at the level of the patient’s head.
The intention of the a priori study planning was to detect a 30% reduction in pain VAS with a common standard deviation equal to the difference at the P = 0.05 level. To reach at least a power of 90%, 30 patients per group would be needed. Because of an uncertain dropout rate, we needed to study at least 86 patients, from which 60 could finally be included. Normally distributed, continuous data were compared by using two-tailed, unpaired Student’s t-tests. Changes within the groups were calculated with two-tailed, paired Student’s t-tests. Data were presented as means ± SD; P < 0.05 was considered statistically significant.
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Results
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We enrolled 86 patients with informed consent in this study. Group 1 consisted of 45 patients and Group 2 of 41 patients. After final diagnosis in the hospital, 15 patients in Group 1 (12 with gastritis, 2 with kidney stones, and 1 with pancreatitis) and 11 patients in Group 2 (9 with gastritis, 1 with kidney stones, and 1 with pancreatitis) dropped out because of a medical diagnosis other than cholelithiasis. No bleeding complication occurred in any of the patients. Consequently, 30 patients in each group entered data analysis.
Patient characteristics were comparable regarding age (47.8 ± 18.2 yr versus 42.9 ± 21.0 yr, Group 1 versus Group 2) and sex (9 men and 21 women in Group 1 versus 6 men and 24 women in Group 2). There was no significant difference in potential confounding factors such as initial core temperature, skin temperature, and subcutaneus temperature. Blood pressure (systolic blood pressure: 140 ± 24 mm Hg versus 140 ± 22 mm Hg, Group 1 versus Group 2, P = 0.89; diastolic blood pressure: 85 ± 14 mm Hg versus 84 ± 8 mm Hg, Group 1 versus Group 2, P = 0.97) and heart rate between the groups before treatment were similar. Before transportation, tympanic temperatures were comparable in both groups (36.5°C ± 0.1°C in Group 1 versus 36.5°C ± 0.2°C in Group 2; P = 0.90).
At the end of transportation, we observed a significant but not clinically relevant difference in tympanic temperature between the groups (36.6°C ± 0.1°C in Group 1 versus 36.2°C ± 0.1°C in Group 2; P < 0.01). On arrival at the hospital, skin temperatures in the upper abdominal region were significantly higher in the warmed patients (41.4°C ± 0.2°C in Group 1 versus 31.1°C ± 1.8°C in Group 2; P < 0.01) (Fig. 1). Also, subcutaneous temperatures in the region above the gall bladder differed significantly between the groups at the end of transportation (39.7°C ± 0.4°C in Group 1 versus 33.2°C ± 1.3°C in Group 2; P < 0.01) (Fig. 2).
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Figure 1. Individual changes in skin temperature before and after transport.  indicates mean; *P < 0.01.
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Figure 2. Individual changes in subcutaneous temperature before and after transport.  indicates mean; *P < 0.01.
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A pain reduction of more than 50%, from 86.8 ± 5.5 mm to 41.2 ± 16.2 mm on the VAS (P < 0.01), was recorded in Group 1, whereas in Group 2, the pain scores remained unchanged (88.3 ± 9.9 mm and 88.1 ± 10.0 mm on the VAS). Pain scores on arrival at the hospital differed significantly between Group 1 and Group 2 (P < 0.01) (Fig. 3).
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Figure 3. Individual changes in pain scores before and after transport. • indicates mean; *P < 0.01. VAS = visual analog scale.
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In Group 1, the VAS score changes for anxiety were significantly reduced (P < 0.01), from 82.7 ± 10.8 mm before treatment to 39.0 ± 14.0 mm after treatment. In Group 2, no significant change of this score was noted (84.5 ± 14.6 mm before and 83.5 ± 8.4 mm after treatment). On arrival at the hospital, the anxiety scores showed a significant difference between groups (P < 0.01) (Fig. 4). Whereas all the patients were vasoconstricted at the emergency site before treatment, there was a significant difference (P < 0.01) between groups in the number of vasoconstricted patients at the hospital (Group 1: 3 constricted and 27 dilated, versus Group 2: 29 constricted and 1 dilated).
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Figure 4. Individual changes in anxiety scores before and after transport.  indicates mean; *P < 0.01. VAS = visual analog scale.
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We observed a significant (P < 0.01) decrease in heart rate in Group 1, from 95.0 ± 6.8 bpm before treatment to 69.8 ± 9.0 bpm after treatment. In Group 2, no significant change was noted (92.8 ± 6.0 bpm before and 90.7 ± 8.9 bpm after treatment). On arrival at the hospital, a significant difference in heart rate was noted between Groups 1 and 2 (P < 0.01) (Fig. 5). There were no significant changes of blood pressure in either group, so the blood pressure values remained comparable between the groups (156 ± 15 mm Hg systolic blood pressure in Group 1 versus 160 ± 14 mm Hg in Group 2 [P = 0.41] and 93 ± 6 mm Hg diastolic blood pressure in Group 1 versus 95 ± 7 mm Hg in Group 2 [P = 0.55]).
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Discussion
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The first finding of this study is that pain resulting from gallstone disease is ranked by the patients at submaximal pain intensity (>80 mm on a 100-mm maximum VAS), comparable to untreated postoperative pain; therefore, there is a need for pain treatment. The main result of this trial is that well performed local warming is a quick and effective treatment for pain caused by gallstones. Furthermore, anxiety is probably reduced as a logical consequence of reduced pain and more comfort. There is no evidence of a direct effect of warming on anxiety. Further, we were not able to measure hormonal changes that could support this theory. However, the changes in the VAS for pain and anxiety are both statistically significant and of clinical relevance. Additionally, we observed a decrease in heart rate in the active warming group and vasodilation as an indirect sign for reduced sympathetic activity.
In most European countries, patients with nonlife-threatening illnesses are transported to the hospital via ambulance in the absence of an emergency physician, because these are called in only for advanced life support (8). Paramedics are not permitted to use any drugs for pain treatment in Europe. In the United States, there are strict limitations concerning pharmacological pain treatment by paramedics (10). Therefore, victims of minor illnesses, who do not require treatment by an emergency physician, often experience pain during the transport. This situation is uncomfortable both for the patient and for the paramedic. In addition to this emotional component, pain provokes autonomic responses that markedly increase adrenergic nerve activity and plasma catecholamine concentrations. The consequence is increased heart rate, hypertension, and arteriolar vasoconstriction (11). All these effects might especially affect old and multimorbid patients on their way to the hospital (3).
Because pain resulting from cholelithiasis is typically severe, is located in the epigastrium and/or the right upper quadrant, and is of relatively abrupt onset, this symptom is a frequent reason for emergency calls. Although these patients experience severe pain, this illness is usually classified as nonlife-threatening; therefore, these patients are transported by paramedics lacking competence in pharmaceutical therapy. Consequently, there is a need for noninvasive and nondrug-based treatment for pain caused by gallstones, e.g., external warming.
There is some evidence in the literature that warming might be helpful: our own recently published data show that patients with minor trauma profit from warming as pain treatment (8). Another study showed positive effects of warming on cardiac pain (12). Also, there seems to be some evidence for warming treatment of menstrual discomfort in young women (13).
Acute pain from cholelithiasis is characterized by high intensity and was rated by our patients at 86 mm on the VAS. This visceral pain, both diffuse and poorly localized, results from the activation of sensory afferents innervating internal organs (14). Only 10% of afferent inflow of the dorsal horn is constituted by visceral afferents, which is a relatively small percentage, considering the large surface of the viscera. There is anatomical and neurophysiological evidence of viscerosomatic convergence in the dorsal horn and supraspinal centers (15). Thus, heat afferents from the body wall converge with visceral high-threshold mechanical receptors and may alter the central viscerosensory processing in the dorsal column, resulting in antinociceptive input. Stimulation-induced analgesia may be produced by other types of sensory stimulation, such as transcutaneous electrical stimulation, and may explain the pain-reducing effect of body heating. However, conclusive data are missing.
Visceral pain is often accompanied by accentuated autonomic reflexes (15). Our data demonstrate increased sympathetic activity in pain patients with cholelithiasis. Reduced sympathetic activity was accompanied by a reduction in the pain scores of our heat patients. The role of the sympathetic nervous system in pain is controversial. Our findings are in accordance with those of Kalmari et al. (16), who demonstrated that sympathectomy attenuates visceral nociceptive responses in rats. In human skin, Lipnicki and Drummond (17) showed that adrenergic supersensitivity enhances thermal hyperalgesia in the presence of noradrenaline. However, Sato et al. (18) demonstrated, in a neuropathic pain model in rats, that exposure to a cold environment augments abnormalities in the pain-related behaviors of neuropathic rats. However, they also found that sympathetic nervous activity is not a predominant factor in the augmenting mechanism. In a model of whole-body cooling (35°C skin temperature) induced in volunteers, Baron et al. (19) could not demonstrate an influence of cutaneous sympathetic vasoconstrictor activity on pain and hyperalgesia after the injection of capsaicin.
However, the same setting enhanced pain and hyperalgesia in patients with sympathetically maintained pain (20). The data mentioned previously are restricted to sympathetically maintained or neuropathic pain and hyperalgesia and may be different from visceral pain. Taken together, the role of the sympathetic nervous system in pain and particularly in visceral pain remains poorly understood. Moreover, other mechanisms, such as spasmolytic effects, may play a role in the pain-reducing effect of body warming.
Furthermore, we observed no negative side effects in our study population. However, there are potential risk factors in our treatment: vasodilation might cause a decrease of blood pressure, and in case of hypovolemia or intraabdominal bleeding, the blood loss might be increased by local warming. We tried to minimize this risk by carefully excluding any patients who might have intraabdominal bleeding and by constantly monitoring vital functions.
There are several reasons for why warming seems to be an ideal way to reduce pain in first aid. First, no drugs whatsoever are required. This means that any physician, nurse, paramedic, or emergency medical technician can perform this treatment immediately at the site of the emergency without having to fear pharmacological side effects or allergic reactions. Second, only brief training is required to learn the simple technique of covering the abdomen with a warming blanket, which is simple to handle. This treatment can be performed by a medical doctor of any specialty or by a paramedic. Furthermore, it is a no-cost treatment once the ambulance owner or the general physician has invested in one warming system, which can be reused for many years.
We conclude that local active warming is an effective and easy to learn treatment for pain resulting from acute cholelithiasis in emergency care. Because there is an improvement of the quality of care in emergency patients, we can recommend this technique for emergency physicians but also for nonacademic personnel, such as nurses, paramedics, firefighters, or emergency medical technicians.
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References
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- Thakore S, McGugan EA, Morrison W. Emergency ambulance dispatch: is there a case for triage? J R Soc Med 2002; 95: 126–9.[Abstract/Free Full Text]
- Lammers RL, Roth BA, Utecht T. Comparison of ambulance dispatch protocols for nontraumatic abdominal pain. Ann Emerg Med 1995; 26: 579–89.[Medline]
- Baum SA, Rubenstein LZ. Old people in the emergency room: age-related differences in emergency department use and care. J Am Geriatr Soc 1987; 35: 398–404.[Medline]
- Razzak JA, Cone DC, Rehmani R. Emergency medical services and cultural determinants of an emergency in Karachi, Pakistan. Prehosp Emerg Care 2001; 5: 312–6.[Medline]
- Diehl AK. Symptoms of gallstone disease. Baillieres Clin Gastroenterol 1992; 6: 635–57.[Medline]
- Chambers JA, Guly HR. The need for better pre-hospital analgesia. Arch Emerg Med 1993; 10: 187–92.[Medline]
- Sauerbruch T, Neubrand M. Nonsurgical management of gallstones. Prog Liver Dis 1992; 10: 193–218.[Medline]
- Kober A, Scheck T, Fulesdi B, et al. Effectiveness of resistive heating compared with passive warming in treating hypothermia associated with minor trauma: a randomized trial. Mayo Clin Proc 2001; 76: 369–75.[ISI][Medline]
- Hahn M, Shore AC. The effect of rapid local cooling on human finger nailfold capillary blood pressure and blood cell velocity. J Physiol 1994; 478: 109–14.[ISI][Medline]
- Brismar B, Dahlgren BE, Larsson J. Ambulance utilization in Sweden: analysis of emergency ambulance missions in urban and rural areas. Ann Emerg Med 1984; 13: 1037–9.[Medline]
- Moltner A, Holzl R, Strian F. Heart rate changes as an autonomic component of the pain response. Pain 1990; 43: 81–9.[ISI][Medline]
- Hartman CH. Response of anginal pain to hand warming: a clinical note. Biofeedback Self Regul 1979; 4: 355–7.[Medline]
- Campbell MA, McGrath PJ. Non-pharmacologic strategies used by adolescents for the management of menstrual discomfort. Clin J Pain 1999; 15: 313–20.[Medline]
- Cervero F, Laird J. Visceral pain. Lancet 1999; 353: 2145–8.[ISI][Medline]
- Al-Chaer E, Traub R. Biological basis of visceral pain: recent developments. Pain 2002; 96: 221–5.[ISI][Medline]
- Kalmari J, Niissalo S, Konttinen Y, Pertovaara A. Modulation of visceral nociceptive responses of rat spinal dorsal horn neurons by sympathectomy. Neuroreport 2001; 12: 797–801.[Medline]
- Lipnicki D, Drummond P. Vascular and nociceptive effects of localized prolonged sympathetic blockade in human skin. Auton Neurosci 2001; 88: 86–93.[ISI][Medline]
- Sato J, Morimae H, Takanari K, et al. Effects of lowering ambient temperature on pain-related behaviors in a rat model of neuropathic pain. Exp Brain Res 2000; 133: 442–9.[Medline]
- Baron R, Wasner G, Borgstedt R, et al. Effect of sympathetic activity on capsaicin-evoked pain, hyperalgesia, and vasodilatation. Neurology 1999; 52: 923–32.[Abstract/Free Full Text]
- Baron R, Schattschneider J, Binder A, et al. Relation between sympathetic vasoconstrictor activity and pain and hyperalgesia in complex regional pain syndromes: a case-control study. Lancet 2002; 359: 1655–60.[ISI][Medline]
Accepted for publication January 3, 2003.
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Abstract
Introduction
indicates mean; *P < 0.01.
