The majority of patients experience much pain after cardiac surgery [1]. Postoperative pain is a multi-dimensional phenomenon in patients undergoing cardiac surgery. Generally, surgical incisions and pulling and cutting the tissues cause pain in all surgeries [2]. In patients undergoing cardiac surgery, at least one chest drain is placed for taking out fluid and lung re-expansion, which causes more stimulation of pain receptors [2-6]. The chest drain is usually removed 1-2 days after surgery [7-9] if the fluid volume is < 100-150 cc and breath sounds are normal for 24 hours [10]. When chest drains remain in the location of surgery, layers of endothelial tissues in the chest cavity attach to them. Therefore, removal of the drains leads to adhesion rupture and stimulation of the parietal pleura and pectoral muscles followed by the release of neurotransmitters and stimulation of pain receptors, eventually resulting in an acute pain [7, 8].

Chest Drain Removal (CDR) is a painful event described by patients to be among the most unpleasant feelings in critical care units [7-9, 11]. Unrelieved pain not only causes psychological suffering but also results in respiratory dysfunction and hypoxia [1, 12].

To date, no international standards exist for the management of CDR pain [4]. Since inserting and removing the chest drain are essential in thoracic surgery, pain management is of particular importance for patients’ welfare [7]. In this context, nurses are responsible for preparing the patients for painful techniques as well as doing them sporadically [6, 12].

Researches have shown that despite using analgesic drugs (morphine and topical analgesics), CDR caused moderate to severe pain [5, 13, 14]. Therefore, using other pain management techniques is mandatory. Today, the emphasis has been put on non-pharmacological methods of pain relief [15, 16]. Ice is a non-pharmacological, easy, and inexpensive method of pain control [15-17], which increases the threshold of pain [7, 18-21]. This method has been widely used in orthopedic surgeries and sports injuries and has shown great effects on pain management [22, 23]. Nonetheless, few studies have used ice to relieve CDR pain and have reported different and somewhat opposing conclusions [6, 7].

Pain is a personal experience that is affected by various factors, such as culture, experiences, perceptions, educational opportunities, family, and psychological factors. These factors make an individual perception of pain [17, 24]. In the previous studies, ice was applied without paying attention to the painful presence of drains on the skin. Thus, the researcher decided to design a method of ice bag application with full coverage to reduce pain caused by movement of the drain that creates pain in the attached places. The intended ice bag covered 5 cm of the skin around the drain and did not exert force and pressure on the drain. It should be noted that the review of the literature revealed no reports on utilization of this method. Considering the researcher’s observations, insufficiency of analgesics for management of CDR pain, and the necessity to take complementary measures for patients with chest drains, the present study aims to evaluate the effect of ice bag application on quality of CDR pain in adult patients undergoing cardiac surgery. We hypothesized that ice bag application would be effective on quality of pain during CDR.

This randomized, observer-blind, crossover study was conducted in patients underwent cardiac surgery during March to July 2011 in the Department of cardiac Surgery of a tertiary teaching hospital of Mashhad-Iran. Based on a pilot study and the sample size formula, a 90-drain sample size was determined for the study (30 drains in each group). However, 34 drains were considered for each group in order to account for the potential dropouts. Therefore, 51 patients were selected via convenience sampling method and were randomly assigned to three groups (17 patients in each group). Inclusion criteria included: age above 18 years, orientation to time, place, and person, having the ability to read and write, speaking Persian, existence at least one mediastinal and one thoracic drain with an 8-cm distance from each other, and passage of at least 1 day from drains insertion. It should be mentioned that two drains were selected in patients with three drains. The exclusion criterion was the unwillingness to continue participation in the research. If the interval between ice bag removal and CDR was more than two minutes and the interval between the two drains removal was more than 30 minutes, the cases were excluded, as well. Modified Short-Form McGill Pain Questionnaire (SF-MPQ) was used to determine the pain quality. This questionnaire included 11 words divided into sensory (n=8) and affective (n=3) dimensions, which were rated from 0 (no pain) to 3 (severe pain). Furthermore, five words were allocated to describing the Present Pain Intensity (PPI) as follows: no pain (0), mild (1), discomforting (2), distressing (3), horrible (4), and excruciating (5). Three words; i.e., brief, intermittent, and continuous, were also used to determine the pain pattern. Other data gathering instruments consisted of a questionnaire containing demographic information and clinical characteristics, the visual analogue scale to evaluate fatigue severity (VAS-F), and Depression, Anxiety, and Stress Scale (DASS-21). The validity and reliability of the VAS-F and DASS-21 have been demonstrated by others [25-27].

The validity of the modified SF-MPQ and demographic information and clinical characteristics questionnaire was confirmed by 10 faculty members of Mashhad University of Medical Sciences. In order to determine the reliability of the modified SF-MPQ, a pilot study was conducted on 12 participants and the reliability of the questionnaire was assessed using a test-retest method. The reliability of the questionnaire was confirmed by r = 0.99 and Cronbach’s alpha = 0.85. This study was approved by the Ethics Committee of the University. Indeed, all patients were informed about the study protocol and procedures and were required to sign written informed consents (IRCT201105146484N1). The data were gathered via interviews as well as reviewing the patients’ medical records. Then, each patient’s chest drain was placed in one study group. Therefore, due to having two chest drains, each patient was randomly assigned to one out of the three cods as follows: ice and placebo (code 1), ice and control (code 2), and placebo and control (code 3). The researcher’s assistant who was not aware of the study groups asked the patients to express their pain quality before and immediately after drain removal based on the modified SF- MPQ.

It should be noted that the chest drains were inserted by a group of surgeons using the same technique and were removed by a team of experienced nurses via the same method during two minutes after removal of the bags. According to the ward rules, first mediastinal and then thoracic drains were removed in the morning shift. In this study, ice and placebo bags made of cotton were designed. The bags were shaped in form of two half-circles with 5 cm radius and 2 cm height. The half-circles were attached together on one side but were open on the other side. In addition, a small hole existed in the middle of the bags whose size was close to that of the diameter of the chest drain. These bags were designed such a way that they covered the whole region surrounding the drains. Ice bags were full of ice, while placebo bags were full of the same size plastic pieces at room temperature. The bags were placed around the drains for 20 minutes and the two chest drains were taken out with a 30-minute interval. After all, the study data were analyzed through the SPSS 14.0 software via Chi-square, Fisher’s exact test, and McNemar’s test. The study groups were compared using one-way ANOVA and LSD post-hoc test for normally distributed data and Kruskal-Wallis and Mann-Whitney tests for non-normally distributed ones. P<0.05 was considered to be statistically significant.

The study subjects consisted of 36 males (70.6%) and 15 females (29.4%) with the mean age of 55.4±11.1 years (range: 29-75 years). Moreover, 50% of the drains were pericardial and 50% were pleural. The three groups were not significantly different regarding the demographic and clinical variables (p>0.05). The main demographic and clinical variables included age, education level, pain tolerance level, worst pain experienced, pain description, received sedatives, fatigue, sleep hours, hemoglobin level, ambient temperature, body temperature, DASS-21 score, Body Mass Index (BMI), having had a chest drain in the past, duration of having the chest drain, distance between the pleural and pericardial drains and the incision site, lengths of pleural and pericardial drains, interval between removing the ice bag and removing the pleural or pericardial drain, and quality of pain (Table 1).

Based on the results of one-way ANOVA, the three groups were not significantly different regarding the mean number of words chosen on the modified SF-MPQ before CDR. The results of Kruskal-Wallis test also indicated that the three groups were not significantly different concerning the mean number of words chosen on the modified SF-MPQ during CDR (Table 2).

According to the results of Kruskal-Wallis test, the three groups were not significantly different regarding sensory, effective, and total pain quality scores before CDR. The results also revealed that the three groups were not statistically different with respect to the mean scores of sensory and affective dimensions during CDR. However, the results of repeated measures ANOVA showed that the three groups’ pain quality scores were significantly different during CDR (p=0.021, f=4.04, DF=2.99). According to the LSD post-hoc test results, no significant difference was found between the placebo and the control group (p=0.530), but significant differences were observed between the ice and placebo groups as well as between the ice and control groups (p=0.008 and p=0.040, respectively) (Table 3).

According to Fisher’s exact test and Chi-square test results, the three groups were not significantly different concerning the selected words, pain pattern, and PPI based on the modified SF-MPQ before CDR. Also, the three groups were not significantly different with respect to the pain pattern and PPI based on the modified SF-MPQ during CDR. However, the results of the Chi-square test showed that the three groups were significantly different regarding the word “hot-burning” during CDR (p=0.009). The three groups were not significantly different regarding the other words on the modified SF-MPQ during CDR. The most commonly used pain quality descriptors reported by the participants were shooting (47.1%), hot-burning (41.2%), aching (29.4%), and fearful (29.4%) in the ice group, shooting (70.6%), fearful (61.8%), hot-burning (55.9%), and sharp (44.1%) in the placebo group, and shooting (50.0%), hot-burning, heavy (44.1%), aching (44.1%), and fearful (41.2%) in the control group. The results of McNemar’s test showed a significant difference in the quality of pain in the three study groups (using words shooting, sharp, hot-burning, and painful when fatigued and touched) before and during CDR.

This study aimed to determine whether the application of ice bags would be followed by a significant decrease in pain quality and use of fewer pain quality descriptors. The study findings showed that the three groups were not significantly different with respect to sensory, affective, and total pain scores of the modified SF-MPQ before CDR. The ice group obtained lower mean scores of the sensory and affective dimensions during CDR in comparison to the other two groups, but the difference was not statistically significant (p=0.088 and p=0.059, respectively). However, the three groups were significantly different concerning the total mean score of the modified SF-MPQ during CDR. Accordingly, using ice bags reduced the total mean score of pain quality. These findings are supported by the Gate Control Theory proposed by Melzack and Wall. Based on this theory, pain has physical, affective, and cognitive components. Application of coldness is believed to influence the affective component of pain. This may lead to a reduction or reversal of the pain impulse by activating descending inhibitory neurons that block ascending nociceptive nerves originating from the substantia gelatinosa. Thus, blocking of ascending nerve impulses “closes the gate” to pain, causing the brain not to interpret the impulses as painful [7]. The proper use of skin irritation, such as coldness, also reduces the pain [16].

The results of the study by Buyukyılmaz and Asti (2009) demonstrated the effects of music and relaxation techniques on the reduction of pain quality score [28]. Cognitive-behavioral therapy could change individuals’ perception of pain and their behavior towards it. It could also lead to better tolerance of pain, reduction of anxiety, and an increase in the effectiveness of analgesics [4, 29, 30].

The current study findings were in contrast to those obtained by Demir et al. (2010) [7]. They used the Long-Form McGill Pain Questionnaire to investigate the effect of coldness on pain quality 15 minutes after CDR. They found that although coldness was effective in the intensity of CDR pain, it had no effects on the total score of pain quality. The difference between the results can be related to the use of the Long-Form McGill Pain Questionnaire and differences in the time of evaluating the pain.

According to the current study findings, the used pain quality descriptors were similar in the three groups before CDR. In line with the previous studies [31, 32], the most widely used words in the sensory dimension were tender (39.2%), heavy (38.2%), aching (38.2%), and shooting (30.4%), which might be due to the visceral nature and deep somatic pain. The most widely used word in the affective dimension was tiring-exhausting (48%). This is consistent with the results of Fox’s study [31], which revealed the rate of tiring-exhausting to be 46.6%. Such fatigue could be attributed to the drains remained in the patients’ chests for a long time (at least 38 hours). Before CDR, the majority of the patients in the current study described the PPI as mild (41.2%) and the pain pattern due to the chest drain as intermittent (43.1%). Breathing, coughing, and moving might displace the drain, which could justify the periodical pain experienced by the patients [33].

The most widely used sensory words to describe pain during CDR were shooting (55.9%), hot- burning (47.1%), aching (36.3%), heavy (34.3%), and sharp (34.3%). The most widely used word in the affective dimension was fearful (44.1%). Compared to before CDR, using the words aching (2%) and heavy (4%) reduced, but shooting (25.5%), sharp (14.7%), and hot-burning (17.7%) increased significantly during CDR. The word aching is associated with a vague sensation, whereas the word sharp is associated with an incisive type of sensation. This difference in the qualitative nature of background and procedural pain may have a physiological explanation. Cutaneous afferent noxious impulses are transmitted from the periphery to the central nervous system through small-diameter myelinated A delta-fibers and smaller diameter unmyelinated C fibers. Pain thought to be transmitted through A-delta fibers is sharp and fast. In contrast, pain thought to be transmitted through C fibers is diffuse, dull, and delayed. C fibers activity may be dominant during immobility, causing background pain as a response to biochemical mediators released from the inflamed tissue. On the other hand, mechanical stimulation may lead to a more dominant activation of A-delta fibers with a more rapid transmission of the stimulus. This difference could lead to a predominant perception of more incisive sensations, such as sharp, stabbing, and shooting, as a result of a procedure [34].

Studies surveying pain during CDR have reported various rates of using words on long- and short-form McGill Pain Questionnaire and other instruments [4, 11, 32]. Patients’ different responses to painful events might result from variations in the tools used to describe pain as well as the concept of pain as a multidimensional phenomenon. The multidimensional model of procedural pain helps recognize that choosing words to describe the quality of pain is a cognitive process. In other words, patients use their judgments to report the quality of pain experienced during CDR. These findings reinforce the long-held belief that pain is not a sensation that varies only in intensity; rather, it has qualitative describable characteristics. This indicates the extent of the language of pain [33, 34].

The present study results revealed a significant correlation between groups and using the word “hot-burning” to describe the pain during CDR. Accordingly, the patients in the ice group used this word less compared to those in the two other groups. Consistently, the study by Kol et al. (2010) showed the effectiveness of ice bag application in the quality of pain resulting from chest drain irritation [35].

In the current study, all words of SF-MPQ were not used by all patients before and during CDR, which is in agreement with the results obtained by Puntillo and Ley (2004) [4]. This indicates that the researcher’s suggestions did not influence the selection of the words.

This study had some strengths and limitations. One of the strong points of the study was designed a bag, which fully covered the area surrounding drain and induced little pressure on the drain insertion site. However, the limitation of the study was its single-blind, randomized, crossover design. Since the patients knew whether they belonged to the ice, placebo, or control groups, a double-blind design could not be employed. Moreover, the distance between the two chest drains was at least 8 centimeters, the bag had a radius of 5 cm, and the time interval between removing the two drains was 30 minutes. However, the probable partial effect of the ice bag on the other drain was not controllable. Future researches could assess the effects of length and type of chest drains on pain associated with CDR.

The present study findings revealed that ice bag was an efficient, inexpensive, and harmless intervention to reduce pain resulted from CDR. In general, non-pharmacological pain relief techniques like using ice bags are acceptable for patients and can be done by nurses. Additionally, such methods do not have the complications and adverse effects associated with pharmacological interventions. The findings of this study can be used in clinical, nursing education, and management services and other researches.