Neonatal Infant Pain Score Research Articles

Progressive Pain Response in Idiopathic Clubfoot Children Undergoing Ponseti Casting: A Prospective Evaluation in 34 Feet.

Investigations of pain and physiologic responses response during Ponseti casting are in the preliminary stage. This short-term study aims to quantify pain responses and to note the variations, if any, during subsequent casting sessions. In this prospective study, the pain parameters were evaluated in 34 clubfeet. Video recording of each casting session was performed 1 minute before casting, during casting, and after 1 minute of casting. The videos were scored objectively using Neonatal Infant Pain Score (NIPS). Heart rate (HR) and oxygen saturation were recorded by using a pulse oximeter. There was progressive increase in pain response until, at the last casting session, it was recorded as NIPS 4 (interquartile range, 1) (P = .02479). Before, during, and after casting, HR rose significantly in succeeding sessions. The mean HR during the first cast session was 175.5 ± 27.2/min, which increased to a mean of 197.3 ± 18.9/min (P = .000282). For the third parameter (oxygen saturation), no differences were observed between the first and last casting sessions. There was moderate pain response during Ponseti casting sessions as demonstrated by the NIPS. It rose significantly toward the last cast. The clubfoot child showed an exaggerated heart rate in succeeding casting sessions. No variations were noticed for oxygen saturation.

Pain behavior of children with bilateral idiopathic clubfoot undergoing Ponseti casting and the effect of non-pharmaceutical pain-relieving agents.

This study prospectively investigated the pain response and physiological parameters [heart rate (HR) and oxygen saturation (SpO2)] during sequential casting in bilateral clubfoot. Additionally, it explored the role of non-nutritive sucking and human care contact on the observed responses during casting. Subjects were allotted to control group (Group A with no intervention) and two intervention groups (Group B: non-nutritive sucking intervention, Group C: human care contact intervention). Neonatal Infant Pain Score (NIPS), heart rate (HR), and oxygen saturation (SpO2) were used to assess the response. The three groups matched in age and gender characteristics of the participants. Pain response was noted across all groups. The left foot demonstrated a statistically significant preexisting tachycardia which rose further during casting (p < 0.01). Intergroup comparisons revealed that the alteration for NIPS during casting was in following sequence (Group A > C > B, p < 0.00001). The effect of interventions offered in Group B and C lasted in the post-cast period as well (B > C). The clubfoot child exhibited moderate pain response during casting of both feet. A tachycardia was noted prior to initiation of second cast which further exaggerated with subsequent cast. Pacifier (non-nutritive sucking) intervention produced better control of pain response than human care contact during casting for both feet.

Efficacy of 2 Nonpharmaceutical (Non-nutritive Sucking and Human Care Contact) Pain Relief Measures for Idiopathic Clubfoot Casted Using Ponseti Technique.

This study aimed at exploring the pain and physiological responses exhibited during Ponseti manipulation and casting in clubfoot infants. In addition, we compared the efficacy of 2 nonpharmaceutical techniques (non-nutritive sucking and human care contact) for tackling these responses. The study included children with unilateral and bilateral idiopathic clubfeet between 15 days to 6 months of age. For comparisons, children were divided into control group without any intervention (group A), non-nutritive sucking group (group B), and human care contact group (group C). Pain score (Neonatal Infant Pain Score), heart rate (HR), and oxygen saturation (SpO2) was assessed before, during and 1 minute after casting. These measurements were compared using statistical methods. There were 16 children (11 bilateral) in group A, 17 (10 bilateral) in group B, and 18 (8 bilateral) in group C. Before casting, the baseline parameters (Neonatal Infant Pain Score, HR, and SpO2) of the 3 groups were comparable. Groups B and C had a significant reduction in pain score at casting and in postcasting period when compared with group A (P<0.05). Group B (at casting-mean: 174.1/min, postcasting-mean: 168.2/min) had the lowest HR both during and after cast application. Group B had the highest SpO2 among all the 3 groups, both during casting (mean: 95.7%) and after casting (mean: 97.4%) (P<0.05). Infants exhibit moderate pain response and altered physiological responses during and after Ponseti casting. Non-nutritive sucking emerged as a better method to lessen these parameters when compared with the conventional technique and human care contact. Level II.

Pharmacokinetics and tolerability of intranasal or intravenous administration of nalbuphine in infants

ObjectivesIntranasal nalbuphine could be a safe, efficacious and non-invasive alternative to parenteral pain medication in infants. We aimed to assess pharmacokinetics (PK) and tolerability of intranasal and intravenous nalbuphine administration...

The Effect of Pre-emptive Oral Melatonin versus Placebo on Post-operative Analgesia in Infants after Thoracotomy for Closed Cardiac Surgeries: A Randomized Controlled Study

BACKGROUND: Thoracotomy pain is one of the severest types of pain that should be managed properly, especially in children. Opioids are the most widely prescribed analgesics for post-operative pain, but they can have a number of undesirable side effects. Melatonin could be employed as an adjuvant analgesic therapy during procedural discomfort as it had no known major side effects. STUDY DESIGN: This was a double-blinded, controlled randomized study. METHODS: Fifty patients divided randomly into two equal groups. One hour before surgery, children in M group (n = 25) were given 0.5 mg/kg orally of melatonin 3 mg tablets) and patients in Group P (n = 25) received a placebo (5 ml of water by syringe 5 ml) orally. Post-operative pethidine consumption over the 1st 24 h (mg) was recorded, the intraoperative fentanyl consumption (HR and ABP) at baseline, 1 min after induction, at skin incision, and every 30 min till the end of the surgery were recorded. Neonatal Infant Pain Score (NIPS) at 4 h, 6 h, 8 h, 12 h, 18 h, and 24 h postoperatively was recorded. Other reported data include demographic data, extubation time, days of ICU stay, and complications. RESULTS: Total post-operative pethidine consumption (mg) over 24 h was significantly lower in M group than P group (3.48 ± 2.23 vs. 7.68 ± 4.52 p = 0.01). Intraoperative fentanyl consumption (ug) was significantly lower in M group than P group (10.28 ± 4.98 vs. 17.08 ± 7.39 p &lt; 0.001). As regards NIPS, it was statistically lower in M group than P group in all times except at 8 h and 24 h with significant difference. CONCLUSION: Oral melatonin is an effective and safe pre-emptive drug as it reduces the total post-operative pethidine consumption over the first 24 h and decreased post-operative pain scores without any unpleasant effects in pediatrics undergoing closed heart surgery.

Comparison of the effectiveness of intravenous fentanyl versus caudal epidural in neonates undergoing tracheoesophageal fistula surgeries.

Background:Caudal epidural has become an inseparable part of pediatric pain relief as it depresses the stress response better than any other form of analgesia, resulting in the reduction in the need for systemic opioids; in addition, it facilitates early recovery and promotes good postoperative respiratory functions.Aim:To evaluate the effectiveness of epidural analgesia in neonates undergoing tracheoesophageal fistula repair in terms of requirement of perioperative fentanyl opioid, postoperative neonatal infant pain score (NIPS), on-table extubation, duration of intubation, reintubation, perioperative hemodynamic response, and any other side effects.Materials and Methods:A comparative, prospective, single-blind, randomized trial on 30 neonates scheduled for tracheoesophageal surgeries were randomly allocated to two groups: group I: neonates receiving caudal epidural block with ropivacaine 0.2%, 1 mg/kg bolus followed by infusion 0.1 mg/kg/h; group II: neonates receiving initial intravenous [IV] fentanyl 1 ug/kg and maintenance with 0.5 μg/kg/h IV bolus.Results:None of the neonates received opioids in group I. There were statistically significant differences in the mean NIPS at 30, 60, 90, 120 150, and 240-min intervals between group I and group II. Further, 80% of neonates were extubated in group 1 compared to 50% in group II, which was statistically significant (P = 0.025). The duration of intubation was more in group II compared to group I, with a suggestive significance of P = 0.093.Conclusion:Caudal epidural infusion provides adequate perioperative analgesia, promotes rapid weaning from the ventilator, and contributes to a successful outcome.

Pharmacometric Analysis of Intranasal and Intravenous Nalbuphine to Optimize Pain Management in Infants.

ObjectivesThe objective of this pharmacometric (PMX) study was to (i) characterize population pharmacokinetics (PPK) and exposure-pain response associations following intranasal (0.1 mg/kg) or intravenous (IV, 0.05 mg/kg) administration of nalbuphine, with the goal to (ii) evaluate strategies for optimized dosing and timing of painful interventions in infants 1–3 months old.MethodsPPK analysis of nalbuphine serum concentrations, prospectively collected 15, 30, and between 120 and 180 min post-dose, utilizing the software package Monolix. The final PPK model was applied to derive individual time-matched concentration predictions for each pain assessment (Neonatal Infant Pain Score, NIPS) after establishment of venous access and urinary catheterization or lumbar puncture. Drug exposure-pain response simulations were performed to evaluate potential benefits of higher doses with respect to a previously proposed target concentration of 12 mcg/L (efficacy threshold).ResultsThirty-eight of 52 study subjects receiving nalbuphine had at least one concentration measurement and were included in the pharmacometric analysis. A two-compartment model with allometric scaling was applied to describe population PK data, with intranasal bioavailability estimated to be 41% (95%CI: 26–56%). Model-based simulations showed that the proposed efficacy threshold (12 mcg/L) is expected to be exceeded with an IV dose of 0.05 mg/kg for 6 min, with 0.1 mg/kg for 30 min and with 0.2 mg/kg for 80 min. This efficacy threshold is not achieved with intranasal doses of 0.1 and 0.2 mg/kg, whereas an intranasal dose of 0.4 mg/kg is expected to exceed such threshold for 30 to 100 min.ConclusionThis PMX study confirmed that bioavailability of intranasal nalbuphine is close to 50%. Exposure-pain response simulations indicated that an intranasal dose of 0.4 mg/kg is required to provide a comparable pain control as achieved with an IV dose of 0.1–0.2 mg/kg. The optimal time window for painful procedures appears to be within the first 30 min after IV administration of 0.1 mg/kg nalbuphine, whereas such procedures should be scheduled 30 min after an intranasal dose of 0.4 mg/kg nalbuphine. Additional clinical studies are warranted to confirm these PMX based recommendations and to further optimize pain management in this vulnerable infant population.

The Effects of Manual and Automatic Lancets on Neonatal Capillary Heel Blood Sampling Pain: A Prospective Randomized Controlled Trial

PurposeThe aim of this study was to determine the effects of manual lancets and automatic lancets on neonatal capillary heel blood sampling pain. Design and methodsThis was a parallel-group, prospective, randomized controlled and observational trial. Participants were randomly assigned (1:1) to the manual lancet (odd days of the month) and automatic lancet groups (even days of the month) for capillary heel blood sampling. The sample consisted of 60 term neonates divided into two groups: Manual lancet (n = 30) and automatic lancet (n = 30). Heart rate, oxygen saturation, duration of blood collection, presence of crying, number of heel punctures, possible complications and pain were measured. ResultsThe manual lancet group had significantly lower oxygen saturation (P = .000), higher mean heart rate (P = .008), more crying neonates (P = .000), higher number of punctures for blood sampling (P = .000) and longer mean duration of blood collection (P = .000) than the automatic lancet group. While there was no difference in the prevalence of elevated temperature, stiffness and edema between the two groups, the automatic lancet group had less redness (P = .028), bruising (P = .000) and a significantly lower mean Neonatal Infant Pain Score than the manual lancet group (P = .000). ConclusionUse of automatic lancets for heel blood sampling helps reduce pain in neonates which is of critical importance. Practice implicationsUse of automatic lancets for heel blood sampling helps reduce pain in neonates. Therefore, neonatal nurses should routinely use automatic lancets in clinical settings to cause less pain in neonates.

High flow nasal cannula and continuous positive airway pressure therapy in treatment of viral bronchiolitis: a randomized clinical trial.

Continuous positive airway pressure (CPAP) has been used in infants with bronchiolitis for decades. Recently, high flow nasal cannula (HFNC) therapy was introduced. We conducted a trial of 50 children with bronchiolitis who were randomized to treatment with CPAP or HFNC. Objectives were to compare the development in respiratory rate, pCO2, and Modified Woods Clinical Asthma Score (M-WCAS) in young children with bronchiolitis, treated with CPAP or HFNC. Secondarily, to compare Neonatal Infant Pain Score (NIPS), treatment duration, treatment failure, and hospitalization length. Median age at inclusion was 2.8 (CPAP group) vs 2.1months (HFNC group). Mean baseline pCO2 was 6.7 in both groups and mean respiratory rate was 60 vs 56 in the CPAP and HFNC group respectively. No differences were observed in development of respiratory rate, pCO2, or M-WCAS. NIPS was higher in the CPAP group. Treatment failure was scarce in both groups. No significant differences in treatment duration or length of hospitalization were observed.Conclusion: In infants and young children with bronchiolitis, HFNC may be an effective and pleasant alternative to CPAP. Larger multicenter studies are needed to further explore differences in treatment failure and treatment duration.Trial registration: www.clinicaltrial.gov. id NCT02618213, registration date December 1, 2015.What is Known:• CPAP has been used for many years for respiratory support in infant bronchiolitis. The method requires special staff skills and may be stressful to the child.• HFNC has been introduced as a newer tool.What is New:• In infants with bronchiolitis, HFNC and CPAP were comparable in decreasing respiratory rate, pCO2, and need for oxygen supply.• Pain score during therapy was lower in the HFNC group.

Extracorporeal shockwave lithotripsy under sedoanalgesia for treatment of kidney stones in infants: a single-center experience with 102 cases.

We present the efficacy of shockwave lithotripsy (SWL) therapy administered with sedoanalgesia in infants with kidney stones. We enrolled 102 patients aged 5-24 months who had kidney stones and received SWL therapy under sedoanalgesia using a Siemens Lithostar Modularis device. Patient and stone characteristics, therapy parameters, pain score, complications, discharge time, and follow-ups were registered and evaluated. Pain score was assessed using a Neonatal Infant Pain Score (NIPS). Postanesthetic discharge scoring system (PADSS) was used for the assessments of postprocedural discharge procedure. Mean age of the patients was 17.2 ± 6.3 months (5-24 months). Mean stone size was 7.9 ± 3.3 mm (5-23 mm). The most common concomitant metabolic disorders were hypercalciuria and hypocitraturia. The stone-free rates of the infants were 70.6, 87.3, and 99.1 % after the first, second, and third sessions of SWL therapy, respectively. The mean NIPS scores procedure during, and at 1 h after SWL procedure were determined as 0.24 ± 0.45 and 0.34 ± 0.47, respectively. There was no statistically significant difference between two pain score values (P = 0.114). The mean discharge time of patients after the SWL procedure were 108.6 ± 27.9 min. Forty-two patients (41.1 %) were followed up. The follow-up period varied between 8 and 48 months (mean 19.5 months); none of those patients showed evidence of diabetes mellitus, hypertension, or renal function impairment. SWL therapy under sedoanalgesia is a safe and efficient treatment modality that can be administered with low complication rates and high stone-free rates in the treatment of renal stones in infants.

Development and preliminary validation of the Neonatal Infant Acute Pain Assessment Scale (NIAPAS)

BackgroundSeveral pain scales are available for neonates, but, unfortunately they are only rarely used in clinical practice. To help with the current situation of unrecognized and under-treated pain in neonatal intensive care units (NICUs), we developed an assessment tool in close collaboration with clinical staff. ObjectivesTo develop a multidimensional scale, NIAPAS (the Neonatal Infant Acute Pain Assessment Scale), that is sensitive to the needs of infants in neonatal intensive care units, and to test the validity, reliability, feasibility and clinical utility of the scale for this population. DesignInstrument development and psychometric analysis. MethodsPain assessments (n=180) were made of 34 neonates born between 23 and 42 weeks gestational age who were undergoing 60 painful procedures (heel lance 77%, tracheal suctioning 23%) in the NICU. Using bedside video recordings, each neonate was observed through three phases of the procedure: 1min before the procedure, during the procedure (lasting from 0.6 to 11.2min, mean 2.6), and 1min after the procedure. In addition, an expert panel (n=5) and nurses (n=26) participated in the validation of the scale. ResultsA pool of 8 pain indicators (5 behavioral and 3 physiological indicators), including the gestational age of neonates as a contextual factor, was identified based on the nurses’ expertise in neonatal intensive care. Scores on the NIAPAS changed significantly across the phases (p<0.001), indicating a good construct validity of the scale. Correlations between the NIAPAS and NIPS (the Neonatal Infant Pain Score) were high (0.751–0.873). The study also demonstrated high coefficients for inter-rater (r=0.991–0.997) and intra-rater reliability (r=0.992–1.00), with an internal consistency of 0.723. The content validity was very good (Mean I-CVI 1.00), as evaluated by the expert group. The nurses agreed that the scale was easy to administer and that it helped decision-making in the pain management of infants. ConclusionsThe NIAPAS was shown to be a valid and reliable scale for assessing acute pain in preterm and full-term infants in the NICU. It allows nurses to evaluate infants’ acute pain especially during painful procedures and help to provide pain relief for the infants.

NEONATAL SÜNNET İÇİN UYGULANAN İKİ FARKLI BUPİVAKAİN DOZUNUN KARŞILAŞTIRILMASI: RANDOMİZE KLİNİK ÇALIŞMA

We aimed to compare the analgesia quality of caudal block of low volume, high concentration bupivacaine to the conventionally used volumes and concentrations of the drug in neonates undergoing circumcision with sole caudal anesthesia.Fifty neonates, undergoing circumcision were randomly assigned to low volume high concentration (group LVHC, n=25) and control groups (group C, n=25). Both groups received a caudal injection: Group LVHC 0.5 ml/kg bupivacaine 0.375% (1.875 mg/kg) and group C 1 ml/ kg bupivacaine 0.25% (2.5 mg/kg). Hemodynamic parameters, block onsets and analgesia periods were compared among the groups. Pain scores were evaluated hourly for 3 hours postoperatively with NIPS (neonatal infant pain score). Statistical analyses were performed with Student's t-test for continuous variables. X(2) and Mann-Whitney U-tests were used for nominal and/or categorical variables.Demographic, hemodynamic data, block onset time (group LVHC and C values were 4.9 +/- 1 vs 5.2 +/- 2 mins, respectively; p=0.53) was similar and postoperative median NIPS (a median value of 0 at postoperative 1, 2, and 3. hours) were identical among the groups (p=0.7, p=0.9, p=1). None of the neonates required additional analgesic for the first 24 hours following the surgery; therefore postoperative analgesic requirement was similar among the groups (p>0.1).Low volume high concentration caudal bupivacaine provided a similar perioperative analgesia quality, time and safety profile compared to conventional bupivacaine doses in awake neonates undergoing circumcision. Low volume, high concentration bupivacaine may be used to reduce the risk of local anesthetic toxicity in outpatient neonates.

Behavioral response to pain in drowsy and sleeping neonates: A randomized control study

In a randomized controlled design, 100 healthy, term neonates in the first week of life, undergoing heel prick for routine screening were randomized to receive a heel prick in either the drowsy/sleeping state or the awake (but not fussy or crying) state. 48 babies in sleeping or drowsy states and 47 in the awake states were analyzed. Infants in the drowsy/sleeping states scored significantly lower on the Neonatal Infant Pain Score (NIPS) (median score 5) at 30 seconds post stimulus compared with infants in higher states of alertness (median score 6). They also had a shorter total duration of cry (29.17 sec ± 8.95 vs 32.67 sec ± 9.82). However, there was no difference in the NIPS score between the two groups at 45 seconds post stimulus. We concluded that babies in the drowsy/sleeping states of alertness at the time of a painful stimulus appear to show a less intense behavioral response to pain as compared to those in the awake state.

MUST SCREENING EXAMINATIONS FOR RETINOPATHY OF PREMATURITY NECESSARILY BE PAINFUL?

This study investigates the impact of the length of the examination, the insertion of eyelid specula, and the indentation of the globe on the pain and stress sensation of premature infants. Ninety-two premature infants in three neonatal wards were included. In two wards, the patients were examined using eyelid specula and scleral indentation as recommended in the official guidelines. In the third ward, the investigation time was minimized and ophthalmoscopy was performed without eyelid specula and scleral indentation. Physical and mental disturbance of the patients was assessed by the Neonatal Infant Pain Score and by monitoring the heart rate. The results were divided into two groups: in the one, eyelid specula and scleral indentation were used, whereas in the other one, they were not used. An independent-samples t-test was performed, which allowed us to calculate the correlation between the way the examination was executed and the condition of the patients. Demographic data and baseline values of heart rate and pain score did not differ between the two groups. Heart rate and pain score during and after the investigation were significantly higher and increased significantly with the duration of the examination for the patients who were investigated using lid specula and scleral indentation. Our study shows that indirect ophthalmoscopy without specula causes significantly less stress to infants than screening with lid specula and scleral indentation.

Postoperative pain control for primary cleft lip repair in infants: is there an advantage in performing peripheral nerve blocks?

Primary cleft lip repair is performed in infants under 1 year of age. The efficacy of an infraorbital nerve block vs intravenous fentanyl was compared in our prospective, randomized controlled trial. Forty-six infants scheduled for primary cleft lip repair were prospectively randomized to one of two groups: group F that received 2 mcg x kg(-1) of fentanyl intravenously and an infraorbital nerve block with 0.5 ml on each side of preservative-free normal saline, and, group B that received bilateral infraorbital nerve blocks with 0.5 ml on each side of 0.25% bupivacaine and 2 ml of preservative-free saline solution intravenously after induction of anesthesia but prior to surgical incision. Patients were observed by a blinded observer for (i) pain scores using neonatal infant pain score; (ii) need for rescue medication in the anesthesia care unit (PACU), in the short stay unit (SSU) and at home and (iii) feeding parameters including difficulty in feeding, time to first feeding and volume of feeds in the PACU, SSU and at home. There were no significant differences in pain scores between the two groups over time (P = 0.98); there were no differences between groups in the number of rescue medications in the PACU, in the SSU as well as at home; however, the time to first rescue medication was greater in the block group compared with the fentanyl group (P = 0.07). There were no significant differences in feeding volumes between groups in the PACU (P = 0.46), SSU (P = 0.57) and at home (P = 0.15). There were no differences in time to initiate feeding between the two groups (P = 0.81). However, there was difficulty with feeding in the block groups compared with the fentanyl group (P = 0.01). The infraorbital nerve block can be effectively used for pain control in infants undergoing primary cleft lip repair. Although children undergoing a nerve block experienced minor difficulties in feeding, there were no differences in feeding volumes or other feeding parameters. This study has shed light into postoperative outcomes besides pain control on children undergoing cleft lip repairs.

Long-term subcutaneous morphine administration after surgery in newborns

To analyze the management of newborns after major surgery receiving morphine subcutaneously and to identify possible side effects. Morphine was administered via a subcutaneous catheter (Insuflon) in 20 newborns after major surgery. Side effects like hypotension, pain during morphine administration and local infection were noted. Morphine dose was adjusted according to the hospital guidelines with the Neonatal Infant Pain Score (NIPS) and the Finnegan withdrawal score. Surgery was performed at the median age of 38 5/7 weeks (range: 32 1/7-49 5/7 weeks). Before starting subcutaneous morphine administration, patients received intravenous morphine for a median of two weeks (range six days to seven weeks). All patients showed good pain relief with no severe side effects. Three patients reacted with crying to the first dose of subcutaneous morphine. No other side effects occurred. Subcutaneous application of morphine with the Insuflon catheter is an alternative to intravenous treatment of postoperative pain in neonates. In this small group pain relief was good and side effects were harmless.

The effectiveness of non-pharmacological pain management in reducing pain from heel stick blood sampling in newborns

Objectives To determine the effectiveness of non-pharmacological interventions to relieve pain associated with heel stick for blood sampling in newborns. Criteria for considering studies for this review Types of participants: Term or preterm neonates both male and female undergoing heel stick during the neonatal period (with postnatal age maximum of 28 days after reaching 40 weeks corrected gestational age) Types of interventions: Any non-pharmacological interventions intended to relieve pain during heel stick, for example, swaddling, positioning, holding, touching, rocking, breast feeding, and oral sucrose/glucose. Types of outcome measures: The outcome measures will be pain or behaviors as assessed by 1. Physiological variables, such as heart rate, respiratory rate, oxygen saturation, or blood pressure, 2. Behavioral variables, such as grimacing, facial expression of pain, or arousal state, 3. Crying measurements, for example, crying time, recovery time, or percentage of time crying 4. Pain scores as measured by: - Neonatal Infant Pain Score - Neonatal Facial Action Coding System - Premature Infant Pain Profile - Other pain measures. Each variable will be treated as a separate outcome measure for analysis.

Rapid Morphine Assessment By Fpia in Preterm Infants in Relation To Pain Assessment By the Neonatal Infant Pain Score

Background: Morphine concentrations(MOR) vary widely and measurements often take days. Most studies look at various doses vs concentration, but not at dose or concentration-effect relationship .Aim: To study whether MOR concentrations measured within hours by Fluorescention Polarisation Immuno Assay(FPIA) can be useful to adjust dosage in preterm infants and to determine a concentration-effect relationship in the first days after birth. Subjects: 10 preterm, ventilated infants, gestational age(mean±SD) 28.9±2.4 wks, birthweight 1257±572 gms. Intervention: MOR 0.1 mg loading dose on day 1, followed by 10 μg/kg/hr continuously. Bloodsamples were taken on day 2, 3 and 5. Neonatal infant pain score(NIPS) was assessed by trained nurses, every 4 hours and once daily during tracheal suction. Results: Mean MOR concentrations on day 2(n=10) were 91±30 μg/l(range 40-161), on day 3(n=7) 81±32(42-146), and on day 5 (n=4) 112±73(52-233). There was no relation between NIPS and MOR concentration, but all infants had scores from 0.3 during MOR, mean 0.7±0.89, as opposed to scores from 3.6, mean 4.1±1.9 before MOR(P<0.001). Scores during suction increased to mean of 4±1.9, range 0.6 and were higher than before suction(P<0.001).Conclusion: MOR in this dosage seems to give good analgesia as assessed by NIPS, concentration can be assessed by FPIA. There is no correlation between NIPS and MOR concentration. NIPS is significantly higher before MOR and during suction.