Sir,

We enjoyed reading the paper of Hoellering et al. on the impact of closed versus open endotracheal suctioning on lung volume and cardiorespiratory changes in ventilated newborns.1 We fully agree that the respiratory and cardiovascular response during and following different suctioning techniques should be evaluated. However, in addition to these variables and similar to the observations on the difference between heel lancing and venous puncture for blood sampling, we would like to suggest to the caregivers consider also the potential relevance of adaptations in procedural techniques to blunt the stress and pain response in neonates. Many procedural interventions during neonatal stay remain a burden as they cause pain or discomfort. Endotracheal suctioning might be one of these techniques to be evaluated 2,3 In a prospective study in ventilated infants in the first 72 h of life, we evaluated the stress response associated with an closed endotracheal suctioning technique and these newly collected data were compared with an earlier reported cohort in whom an open suctioning technique was performed.4 The standardized endotracheal suctioning procedure currently used in the unit can be described as follows: 0.2 ml normal saline (0.9% sodium chloride) is injected into the tracheal tube by the side hole of the Trach Care Mac®. This is a closed suction system. The suction catheter is introduced into the endotracheal tube hereby ensuring that the tip of the suction catheter will be just at the tip of the endotracheal tube. This is feasible since distance is clearly indicated on the suction catheter and measurement of the length of the endotracheal tube and the connection to the ventilator can be done before the procedure. Finally, the suction catheter is progressively retracted under continuous negative pressure (50 -100 mmHg). Stress and pain expression were evaluated before, during and after endotracheal aspiration by clinical and endocrine profiles. All infants were videotaped for 2 min before (-5 min), during and after the procedure (5, 10, 20, 30, 40, 60 and 80 min). Videotapes were scored afterwards with a validated pain assessment instrument for this age group, the Neonatal Infant Pain Scale (NIPS). The NIPS scale consists of 6 behavioural (facial expression, breathing patterns, arms, legs and state of arousal, each grade 0 or 1 point and crying, graded 0, 1 or 2 points, resulting in a score between 0 and 7) items. Clinical characteristics and the administration of continuous background opioids were registered. Vital signs (heart rate, mean arterial pressure, MAP) were recorded before (-60, -10, -5), during and after (5, 10, 20, 40, 60, 80 min) the intervention. Endocrine response was evaluated by sequential measurement of serum (nor)adrenaline levels. Blood samples (heparin microcontainer, 0.4 ml) were collected before (-5 min) and after (5, 10, 20, 40 min) initiation of endotracheal suctioning. All blood samples were stored on ice until centrifugation. Serum samples were stored at –80°C until analysis. Concentrations of (nor)adrenaline were measured by HPLC using fluorimetric detection. Only infants who had an arterial line in place for clinical indications were included to enable blood sampling (maximal 1 ml/kg) without further stress or pain. Infants on continuous (nor)adrenaline infusions were excluded to enable evaluation of the endocrine stress response while infants on muscular relaxants were excluded to enable clinical evaluation. Paired Wilcoxon was used to compare vital signs, adrenaline and noradrenaline levels before, during or after endotracheal suctioning.3 Ten procedures in 10 infants were recorded. Median gestational age was 34 weeks (range 27-39), median postnatal age was 29 h (range 12-68). Six infants were on continuous opioids (fentanyl, 1-3 ìg/kg/h or tramadol, 3-8 mg/kg/day) infusion. Median duration of the suctioning procedure was 72 (range 35-110) seconds. Median heart rate (HR) before suctioning was 137 (range 129 – 147) beats per min (bpm) and median MAP was 44 (range 40 – 52) mmHg. After five min, median HR was 143 (range 136 – 163) bpm and median MAP was 45 (39 – 55) mmHg. There was a significant increase in HR 5 min after initiation of the procedure when compared to pre-procedural findings (p<0.05) which did not remain significant after 10 min. No episodes of bradycardia (<80 bpm) were documented during or after endotracheal suctioning. There was no significant increase in MAP at any time after initiation of the procedure. Median noradrenaline before endotracheal suctioning was 1.0 (range 0.5- 2.4 nmol/l) and median adrenaline before endotracheal suctioning was 0.08 (range 0.05 – 0.33 nmol/l). Median nor- and adrenaline 5 min after initiation of endotracheal suctioning were 1.5 nmol/l (range 0.6 – 2.4) (p<0.05) and 0.11 nmol/l (0.06 – 0.42) (NS). Median procedural increase in nor- and adrenaline was 30% and 15% respectively. Videotapes were scored afterwards by 2 caregivers using the NIPS. Both caregivers had experience with the NIPS score. Median NIPS was 0 (range 0 – 1) before suctioning. During suctioning, median NIPS was 1 (range 0 –7). After 5 and 20 min, median NIPS was 0 (range 0 – 4). We can compare trends in vital signs in this cohort (n=10) with an earlier cohort (n=13) from the same NICU using a disconnection technique.4 In this earlier cohort, changes in heart rate and MAP were more pronounced since mean change in heart rate was 23 (SD 17) and median change in heart rate was 10 bpm (SD 14, range -1 to + 37 bpm). In a bench test evaluation of a closed tracheal suction system, it was concluded that continuity of ventilation volume or pressure delivery during suction are not preserved and therefore can not explain the reported reduction in suction-related hypoxia.5 It is not unlikely that the blunted stress response in part explains this reduction. In addition to cardiovascular or respiratory characteristics of a suctioning technique, such techniques should also be evaluated on the associated stress response in neonates.

References

1.Hoellering AB, Copnell B, Dargaville PA, Mills JF, Morley CJ, Tingay DG. Lung volume and Cardiorespiratory changes during open and closed endotracheal suction in ventilated newborn infants. Fetal Neonatal Ed doi:10.1136/adc.2007.132076 2.Simons SH, van Dijk M, Anand KS, Roofthooft D, van Lingen RA, Tibboel D. Do we still hurt newborn babies ? A prospective study of procedural pain and analgesia in neonates. Arch Pediatr Adolesc Med 2003;157:1058-64. 3.Allegaert K, Tibboel D. Shouldn’t we reconsider procedural techniques to prevent neonatal pain ? Eur J Pain 2007;11:910-2. 4.Bernert G, von Siebenthal K, Seidl R, Vanhole C, Devlieger H, Casaer P. The effect of behavioural states on cerebral oxygenation during endotracheal suctioning of preterm infants. Neuropediatrics 1997;28:111-5. 5.Cordero L, Sananes M, Ayers LW. Comparison of a closed (Trach Care MAC) with an open endotracheal suction system in small premature infants. J Perinatol 2000;20:151-6.