|Year : 2008 | Volume
| Issue : 5 | Page : 519
Assessment of Sedation and Analgesia in Mechanically Ventilated Patients in Intensive Care Unit
Udita Naithani1, Pramila Bajaj2, Sanjay Chhabra3
1 Asstt. Prof., Department of Anaesthesia, R N T Medical College, Udaipur, Rajasthan., India
2 Prof.& Head, Department of Anaesthesia, R N T Medical College, Udaipur, Rajasthan., India
3 Ex-P.G.Student, Department of Anaesthesia, R N T Medical College, Udaipur, Rajasthan., India
|Date of Acceptance||25-May-2008|
|Date of Web Publication||19-Mar-2010|
II-238, OTC Scheme, Chetak Mark, Udaipur(Rajasthan)
Post traumatic stress resulting from an intensive care unit(ICU) stay may be prevented by adequate level of sedation and analgesia. Aims of the study were reviewing the current practices of sedation and analgesia in our ICU setup and to assess level of sedation and analgesia to know the requirement of sedative and analgesics in mechanically ventilated ICU patients. This prospective observational study was conducted on 50 consecutive mechanically ventilated patients in ICU over a period of 6 months. Patient's sedation level was assessed by Ramsay Sedation Scale (RSS = 1 : Agitated; 2,3 : Comfortable; 4,5,6 : Sedated) and pain intensity by Behavioural Pain Scale (BPS = 3 :No pain, to 16 : Maximum pain). BPS, mean arterial pressure(MAP) and heart rate(HR) were assessed before and after painful stimulus (tracheal suction). Although no patient had received sedative and analgesics, mean Ramsay score was 3.52±1.92 with 30% patients categorized as 'agitated', 12% as 'comfortable' and 58% as 'sedated' because of depressed consciousness level. Mean BPS at rest was 4.30±1.28 revealing background pain that further increased to 6.18±1.88 after painful stimulus. There was significant rise in HR (10.30%), MAP (7.56%) and BPS (40.86%) after painful stimulus, P<0.0001. The correlation between BPS and Ramsay Score was negative and significant (P< 0.01). We conclude that there should be regular definition of the appropriate level of sedation and analgesia as well as monitoring of the desired level, using sedation and pain scales as a part of the total care for mechanically ventilated patients.
Keywords: Sedation and analgesia, Ramsay Sedation Scale, Behavioural Pain Scale, ICU, mechanical ventilation
|How to cite this article:|
Naithani U, Bajaj P, Chhabra S. Assessment of Sedation and Analgesia in Mechanically Ventilated Patients in Intensive Care Unit. Indian J Anaesth 2008;52:519
|How to cite this URL:|
Naithani U, Bajaj P, Chhabra S. Assessment of Sedation and Analgesia in Mechanically Ventilated Patients in Intensive Care Unit. Indian J Anaesth [serial online] 2008 [cited 2013 May 25];52:519. Available from: http://www.ijaweb.org/text.asp?2008/52/5/519/60668
| Introduction|| |
Sedation and analgesia are now regarded as an integral part of treatment of the patients in the intensive care unit(ICU) instead of being an unpleasant but necessary and minor issue. Nearly all patients in the ICU experience pain, whether it is result of procedures performed on them, the disease process, catheters or tubes inserted into them, or because they are immobile and cannot shift position.  The sequelae of severe untreated pain can be long lasting psychological effects on the patient, together with haemodyanamic changes like tachycardia, hypertension and increase in systemic vascular resistance, causing an increase in myocardial oxygen consumption and demand, that may result in myocardial ischemia. There may also be a deleterious effect on the immune system in an already compromised patient who is trying to combat a serious illness but foremost it is inhumane not to adequately treat pain. 
The importance of monitoring the level of sedation and analgesia has only recently been realized. Accordingly intensivists require tools that measure the effectiveness of sedation and analgesia in individual patient in relation to the objectives, such instrument should be simple and user friendly at the bed side.
The most commonly used sedation scale is the Ramsay Sedation Scale.  Relying on changes in vital signs as a primary indicator of pain can be misleading because these may also be attributed to underlying pathophysiologic condition, homeostatic changes and medication. Absence of increased vital signs does not indicate absence of pain.  Pain experts agree that a patient's self report of pain intensity (like Visual Analogue Scale) is the most valid measure, but assessing pain in critically ill patients who are unable to communicate effectively for several reasons including tracheal intubation, reduced level of consciousness, sedation etc is a great challenge.  Payen et al (2001) described Behavioural Pain Scale (BPS) to assess pain in critically ill ventilated patients, having three subscales : facial expression, upper limb movement, and compliance with mechanical ventilation. 
Inappropriate administration of sedation has potentially serious consequences. Insufficient sedation can precipitate myocardial ischemia or ventilator asynchrony. Excessive sedation may create prolonged alteration of consciousness which could lead to an increased duration of mechanical ventilation. This in turn may predispose to an increased risk of ventilator associated pneumonia, an increased time in the ICU and an increased cost of care. 
Since, comatose patients or patients with depressed consciousness level need less or no sedation and most of the time administration of an analgesic drug may satisfy the sedative requirement of patients.  Although, the higher the sedation level the lower the ability to express painful behaviour, the current empirical evidence support claim that pain in sedated or unconscious ICU patients is underrated or undertreated. 
Many studies,,, conducted in different types of ICUs have stressed on the use of sedatives and analgesics in the management of mechanically ventilated patients but studies are lacking on how their use should be individualized according to diagnosis and consciousness level of patients.  With this background we conducted our study to monitor the level of sedation and analgesia using appropriate scales to know the requirement of sedative and analgesics in mechanically ventilated patients in ICU. Present practices of using sedative, analgesics and neuromuscular blocking agents in ICU were also examined.
| Methods|| |
This prospective observational study was conducted in 50 adult patients above 16 years of age who were mechanically ventilated for > 48 hours in Medical Intensive Care Unit (MICU) over a period of 6 months in a tertiary care centre attached to a teaching hospital of a developing country. The patients from surgical ICU who required ventilation postoperatively were not included in the study. The hospital ethical committee approved the study protocol and because this was an observational study and not interfering with prescribed managment of the patients in ICU, informed consent from the patients was not required. We have 6 bedded medical ICU with 3 microprocessor controlled ventilators with AC, SIMV, BiPaP modes. As the patients were taken on the ventilator, demographic variables, diagnosis, indication of ventilation were noted as per proforma. The doses of sedative, analgesic and neuromuscular blocking agents if patient had received during ventilation were also noted. Haemodynamic variables (BP, HR) and level of sedation and analgesia using appropriate scales were measured at 12 h interval (8 A.M. and 8 P.M.) till four consecutive readings were obtained for each patient indicating ventilation for 48 hours. Seventy two patients were taken on the ventilator during 6 month period, extending from July 2007 to December 2007, 22 patients were dropped out from the study because they could not complete the criteria of 48 hours ventilation (i.e., 4 reading couldn't be achieved), either due to mortality or they were weaned off the ventilator. Therefore 50 consecutive patients who were ventilated for > 48 hours were included in the study that was the basis of sample size of 50.
Patient's sedation level was assessed using Ramsay Sedation Scale (RSS)  as follows.[Additional file 2]
Patients were grouped in 3 categories: A - Agitated, B - Comfortable& C - Sedated as per RSS 1; 2,3;& 4, 5, 6, respectively.
Intensity of pain was assessed using Behavioural Pain Score (BPS)  as follows:[Additional file 1]
Evaluation of BPS and physiological variables (systolic blood pressure, diastolic blood pressure and heart rate) was made at rest and during tracheal suctioning which was used here as painful procedure to know analgesia levels at rest and during painful stimulus. Tracheal suction was selected as painful procedure because its painful character had been demonstrated previously and because it was part of the routine care that was normally planned for these patients. Mean arterial pressure (MAP) was calculated by:
Diastolic blood pressure + Pulse pressure / 3
| Statistical analysis|| |
Quantitative variables were expressed as mean ± SD. Student 't' test was applied to find the significant changes before and after suction on various variables. We hypothesized that a significant correlation would be found between the BPS scores and the two physiological variables (MAP and HR) that were supposed to measure the same concept (pain). We also tested the correlation between BPS and Ramsay scale. Spearman nonparameteric coefficient was used for correlations. Significance for all statistical tests was set at P = 0.05.
| Results|| |
There were 50 patients of medical ICU enrolled in our study out of which 60% were males (mean age 42.47±19.78 years) and 40% were females (mean age 35.58±15.63 years). During present study no patient received any sedative, analgesic or neuromuscular blocking agent and no sedation or pain measurement scales were in use in ICU.
Majority of patients were ventilated in which respiratory distress was due to snake bite (24%), cerebrovascular accident (18%), Guillain Barre Syndrome (10%), febrile encephalopathy (10%), respiratory causes like COPD, asthma, ARDS (10%) and others (28%MODS, sepsis, quadriparesis, hepatic encephalopathy, congestive heart failure, fat embolism and shock).
The mean BPS at rest was 4.30±1.28 which showed that the patients were having pain even at rest during ventilation. The BPS increased after painful stimulus to 6.10±1.88 which revealed significant rise (41.86%, P = 0.0001). There was 10.30% rise in HR and 7.6% rise in MAP after painful stimulus which were highly significant, P < 0.0001 [Table 1].
Mean Ramsay Score was 3.52±1.92. Fifteen (30%) patients were agitated (category A), 6 (12%) comfortable (category B) and 29 (58%) were sedated (category C) as per Ramsay Sedation Score. There was significant rise in heart rate, MAP and BPS in all three categories of Ramsay score after tracheal suction [Table 2].
To know the requirement of analgesics in individualized way, patients were divided in three BPS groups:
Group I : BPS = 3 (no pain at rest)
Group II : BPS > 3 (pain at rest)
GroupIII : After tracheal suction rise in BPS = 0
(no pain at painful stimulus)
Each BPS group was further assessed according to diagnosis and consciousness level of patients as indicated by Ramsay category A, B and C[Table 3]. Seventeen (34%) patients did not have rest pain (group I) with mean Ramsay score 5.00±1.37; out of which 14 patients were in category C, 3 patients in category B and none of the patient in category A. This showed that the patients with depressed level of consciousness might not have pain at rest. On the other hand we found 33 (66%) patients having rest pain (group II) with mean Ramsay score 2.76±1.71, out of which 15 patients were in category A and C each and 3 patients in category B. There were 7 (14%) patients who had not expressed pain after painful stimulus (group III) with a high mean Ramsay score (5.43±0.53) and all patients fell into category C of Ramsay score.
Correlation between BPS, Ramsay Score and physiological variables was assessed at rest [Table 4] and after painful stimulus [Table 5]. At rest no significant correlation was found between the BPS scores and the physiological variables (HR and MAP). After painful stimulus there was significant positive correlation between increase in heart rate and BPS (r = 0.369, P = 0.008). When the correlation between the BPS scores and Ramsay score was investigated, as expected, a significant negative correlation emerged both at rest (r = -0.373, P = 0.008) and after painful stimulus (r = -0.414, P = 0.003). The higher the sedation level, the lower the BPS scores [Figure 1].
| Discussion|| |
Sedation in critically ill patients is a complex issue and at the same time an important concept for ensuring patient comfort. Similarly, adequate treatment of pain in ICU patients should be an integral part of ICU man agement, as inadequately treated pain leads to a series of complications that may counteract the success of ICU treatment ,,, .
In our study we found that no patient was given sedative, analgesic or neuromuscular blocking agent in their treatment chart and no sedation or pain scales were in use for monitoring in ICU. Since in our set up ICU runs under guidance of physicians, they call anaesthesiologists only to intubate the patients and to take them on ventilators if needed. Similarly weaning and extubation are done by anaesthesiologists on call basis. Regular posting of anaesthesiologists is not there in ICU as intensivists. Some patients who were agitated and fighting with ventilators either had been tied with beds or held by attendants to make ventilator therapy possible. Physicians were reluctant to add sedative and analgesic drugs in their treatment regime on regular basis when they were asked.
On the contrary, a study conducted in developed country like Sweden, Samuelso et al reported that mechanically ventilated patients were routinely sedated in 91% of ICUs. Midazolam or propofol in combination with an opioid were the drugs preferred by 76%. Heavy sedation was most usual in 63% of ICU, however, 78% nurses preferred light level of sedation (P = 0.001). Only 16% used sedation scales.  Similarly, Murdoch et al reviewed intensive care sedation in British practice (323 units) and reported that it is standard practice in Britain to sedate all patients receiving neuromuscular blocking agent because of concern about awareness. Propofol, midazolam , fentanyl, alfentanil and morphine were the most widely used drugs in adult intensive care, whilst in paediatric practice morphine, midazolam and chloral hydrate were the most widely used drugs. Different sedation scoring systems used were Ramsay (40 units), Adden brookes (13), Cook (11), Sheffield (8 units). 
The vast majority of experts agree that the adequate level of sedation level is different for each patient, according to their different clinical circumstances (severity of the respiratory insufficiency, haemodynamic state, etc.). 
In our study although no patient had received sedative or analgesics on regular basis, only 30% patients were agitated indicating need for sedation; 12% and 58% came in comfortable and sedated category of RSS respectively indicating depressed level of consciousness and did not need sedation.
Our study agree with the Carrasco et al who stated that sedation must be adjusted in an individualized way according to diagnosis, and consciousness level of patients. This approach is currently the best way to administer sedation. The best approach is to maintain a light and comfortable level of sedation, if it is reasonably possible in order to decrease the incidence of adverse effect of high doses of sedative. The ideal sedation depth for most of these patients is mean sedation level 3 of Ramsay scale or between 8 and 12 points of Glassgow Coma Scale.  Because oversedation has been associated with prolonged time on mechanical ventilation, increased risk of ventilator associated pneumonia and other complications.  Undersedation (Ramsay level 1) may result in patient anxiety and agitation, which can further harm to the patient and as well as staff. 
In contrast, Gunten et al reported that sedation should be provided to all patients even those who are comatose. The dose needed to control symptoms will depend to some degree on the neurological status of the patient and the amount of similar medication used up to the time of extubation. 
In our study mean BPS at rest was 4.30±1.28 showing baseline pain. HR, MAP and BPS increased significantly after painful stimulus in all Ramsay categories A, B and C. This indicates although patients with depressed consciousness (category B and C) did not require sedation but analgesics are must in all Ramsay categories.
We emphasize that the sedation assessment scale should direct clinician to first evaluate and treat pain, before sedation is assessed. Sedative therapies should be used as an adjunct to analgesia because untreated pain will not be effectively resolved through sedative regimens  and as inadequately treated pain leads to a series of complications that may counteract the success of ICU treatment. 
Pain is a stressor that produces sympathetic stimulation (tachycardia, change in arterial blood pressure, diaphoresis, and change in pupillary size)  . These physiological variations can help to detect pain among patients with impaired mental status.  We observed a significant rise in heart rate (10.30%) and MAP (7.5%) during painful procedure that coincides with the observation of clinicians who generally associate pain with a variation of 10 to 20% in physiological variables.  Two physiological domains of the Comfort Scale address that increases in heart rate and blood pressure are related to pain and sedation and are appropriate markers for agitation. A 15% or greater change in heart rate or blood pressure was considered an indicator of changes in physiological status that related to lack of comfort and is an appropriate level of change that can be recognized clinically. 
However, it is agreed that these physiological indicators are inherently difficult to put into a separate variable and lack specificity in the ICU; they can be influenced by many medications (vasopressors, beta blockers, antiarrhythmics, sedative drugs, etc.) and pathological conditions (sepsis states, shock, hypoxia and fear)  , moreover, absence of increased vital signs does not indicate absence of pain. 
Aissaoui et al conducted a study in 39 mechanically ventilated patients using BPS and Ramsay score. There was increase in physiological variables but no significant correlation was found between BPS score and the two physiological variables  almost similar to our study. In present study the correlation between BPS score and Ramsay scale was negative and significant. The logical direction of the association was the higher the sedation level, the lower the ability to express painful behaviours. ,
Our study emphasizes that sedation and analgesia are important in the management of patients who require mechanical ventilation as found by others ,, and it should be better administered according to an individual's need. 
Our study had some limitations like a small sample size to do statistical analysis, conducted in medical ICU, not including post surgical patients and no patient was receiving sedative and analgesic. We used only subjective assessment scale (Ramsay scale and BPS-subjective aspect of recorder) and no objective methods like bispectral index, auditory evoked potentials, electroencephalography were used. In spite of above limitations of the study some careful conclusions can be drawn.
To conclude, almost all critically ill patients have pain whether it is iatrogenic pain from procedures or positioning. If pain is addressed adequately, the need for sedation is very-very small. Traditional pain indicators such as fluctuations in haemodynamic parameters are not always an accurate measure for the assessment of pain in mechanically ventilated ICU patients. Therefore, more objective pain assessment measures like BPS are essential. Consequently, the routine assessment of sedation and analgesia should be a part of total care for critically ill patients, in a manner similar to that in which cardiorespiratory parameters are monitored. The appropriate use of instruments to monitor sedation and analgesia can improve the sedative and analgesic treatment that we deliver to our patients. Our study has indicated that Ramsay score should be kept in comfortable range (RSS=2,3)and BPS=3(No pain) and sedative should be given when RSS=1(agitated) and analgesics when BPS>3(Pain).
New drug development and recent findings in new ventilation strategies allow for management of sedation and analgesia that is better tailored to an individual's need. We anticipate that future contribution to this forgotten field will result in improvements in the quality of care that our patients need and deserve.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]