January - February - March 2004

Chair & Editor
Timothy R. Myers, BS, RRT
Pediatric Administrative Manager, Dept. of Respiratory Care
Rainbow Babies & Children's Hospital
Asthma Clinical Studies Coordinator, Dept. of Pediatrics
Case Western Reserve University
11100 Euclid Avenue #6020
Cleveland, OH 44106
(216) 844-1954
FAX (216) 844-5246
timothy.myers@uhhs.com

Co-Editors
Melissa K. Brown RCP, RRT-NPS
Instructor
Respiratory Therapy Program
Health Sciences Department
Grossmont Community College
8800 Grossmont College Dr.
El Cajon, Ca. 92020
619-743-4032
mkbrown@ucsd.edu

Kathleen Deakins, RRT-NPS
Rainbow Babies and Children's Hospital
11100 Euclid Ave
Cleveland OH 44110
(216) 844-1954
Fax: 216-844-5246
kathleen.deakins@uhhs.com

by Timothy R. Myers BS, RRT-NPS

Hopefully, all of you had a memorable holiday season and are ready to take on the challenges of our profession and specialty in 2004. At last year’s AARC Congress in Las Vegas, the Neonatal-Pediatric Section was well-represented with many exciting lectures and symposiums. We also honored our 2003 Specialty Practitioner of the Year at the Awards Ceremony on Monday, December 8, and held our Neonatal-Pediatric Section Meeting on Wednesday, December 10. At this time, we also welcomed our new section chair-elect, Michael Tracy, who will assume the chair in December of 2004. (See article in this issue for more on Michael and our Practitioner of the Year, Brian Walsh.)

A major change for all the AARC specialty sections in 2004 is the conversion of the section Bulletins to the electronic format. As you can see from this inaugural issue, the new Bulletin will now be delivered to members via e-mail notification. If you know of section members who have yet to file an e-mail address with the AARC, please remind them to do so ASAP so they may be alerted to upcoming issues. Members with e-mail addresses on file will also receive a monthly E-Newsletter, full of news and information related to our specialty.

The other major initiative for 2004 will be to upgrade and enhance the section homepages on the AARC web site. We received many good ideas and recommendations from members in attendance at the section meeting in Las Vegas for upgrades and modifications to the neonatal-pediatric homepage. If you have any ideas or thoughts, drop me an e-mail at timothy.myers@uhhs.com, or give me a call and we will take them into consideration.

As you can see, the section has been busy working to advance the initiatives of its members and the Association over the last several months. So share this information with your peers and colleagues, and extol the virtues and benefits of joining the AARC and our specialty section. I also encourage any of you out there who haven’t already joined us on the Neonatal-Pediatric E-Mail List to do so soon. It is an excellent way to share ideas in a quick format with your fellow section members around the country..

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A 607 gm infant was born to a 24-year-old mother, following uncontrolled premature labor. The patient was intubated in the delivery room shortly after birth due to poor respiratory effort. Apgar scores were 2 at one minute and 4 at five minutes. The patient was transferred to the neonatal intensive care unit and treated for respiratory distress syndrome with two surfactant replacement doses. Acute pulmonary hemorrhage developed on the second day of life. A short term of high frequency oscillatory ventilation was implemented, followed by SIMV with time cycled pressure-limited mode during the course of mechanical ventilation.

The patient (625 gm) was extubated at day of life 25 to variable flow nasal CPAP delivered via mask at +6 cm H2O, FIO2 0.60, and caffeine bolus. A capillary blood gas was obtained with the following results: pH 7.37, PCO2 71, PO2 36, HCO3 42, and BE +14.

Twelve hours following extubation, the patient required bag-mask ventilation for an acute and severe episode of oxygen desaturation, apnea, and bradycardia. A chest radiograph taken prior to initiating nasal SIMV (nSIMV) revealed unilateral atelectasis. An infant nasal cannula was attached to a 2.5 endotracheal tube adapter and connected to a ventilator circuit. A nasal cannula was used as opposed to nasopharyngeal prongs as NP prongs wouldn't fit into the tiny nares. An abdominal sensor was applied to achieve synchrony during non-invasive ventilation. SIMV rate 18 bpm, PIP 20 cm H2O, PEEP +5 cm H2O, and FIO2 0.60 were maintained. Repeat capillary blood gas after four hours revealed pH 7.38, PCO2 59, PO2 44, HCO3 37, BE +11.5. Respiratory rate remained in the 50s with an occasional episode of apnea or bradycardia. A chest radiograph was repeated nine hours following initiation of nSIMV, revealing resolution of atelectasis.

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Thanks to advances in neonatal care (antenatal steroids, nutrition, ventilator management, etc.), our patients are now ready to extubate at younger gestational ages, after less time on the ventilator, and weighing less. This does not mean they are always capable of sustaining spontaneous respiration. Many studies suggest NCPAP is useful in augmenting spontaneous respiration and preventing extubation failure. Pediatric and adult patients at risk for intubation may avoid intubation with NIPPV, but this methodology is not nearly as accepted in neonatology.

The Cochrane Library (Issue 4, 2003) did a meta-analysis to determine whether NIPPV compared to NCPAP decreased the rate of extubation failure without adverse effects.(1) Randomized trials comparing NIPPV with NCPAP in preterm infants being extubated were selected. Data regarding clinical outcomes, including extubation failure (the primary outcome), endotracheal reintubation, rates of apnea, gastrointestinal perforation, feeding intolerance, CLD, and duration of hospital stay, were extracted independently by three reviewers.

Three trials meeting inclusion criteria were identified: Barrington 2001, Friedlich 1999, and Khalaf 2001.(2,3,4). Each of these trials used synchronized NIPPV. Each trial showed statistically significant benefits for patients enrolled in the NIPPV arm in preventing extubation failure. The reviewers also state that the effect is clinically significant: “NIPPV is a useful method of augmenting the beneficial effects of NCPAP in preterm infants. Its use reduces the incidence of symptoms of extubation failure more effectively than NCPAP . . . there is a reassuring absence of the gastrointestinal side effects that were reported in previous case series. In this systematic review, approximately one quarter of all preterm infants allocated to NCPAP failed extubation and therefore the opportunity exists to further improve outcomes for infants thought to no longer require an endotracheal tube.”

Among the outcomes:

• Endotracheal reintubation: Not all NCPAP infants reaching extubation failure criteria were reintubated, as a varying proportion of infants in each trial were offered rescue therapy with NIPPV. The pooled estimate of rates of reintubation favored NIPPV.
• Chronic lung disease: There was a trend, but not of statistical significance, toward reduced rates of CLD noted in two trials (Barrington and Khalaf). There were no reported differences in the length of hospital (LOS) stay. The reviewers note that frequent use of crossover/rescue use of NIPPV makes differences in the LOS difficult to ascertain.
• Apnea: Barrington used a continuous multi-channel recording to detect apneic events. Again there is a trend towards reduced numbers of apneas in the NIPPV group.
• Miscellaneous: Comparisons of NIPPV and NCPAP in these studies are potentially confounded by differences in mean airway pressure (MAP) between groups. None of the authors present data on MAP in the NIPPV group, but this may have been higher than the CPAP level in the other group. Differences in outcomes may be due simply to a higher MAP in the NIPPV group. The difference in MAP may be the most fundamental factor in reaching or not reaching failure criteria.

All three studies used synchronous NIPPV. Individual NICUs may interpret these results differently. The provision of S-NIPPV requires a ventilator capable of delivering this mode of support. Less expensive modes of NCPAP delivery exist, and issues of resource allocation may be important in some hospitals where S-NIPPV may be reserved for infants who “earn it.” Alternatively, well-equipped units may elect to “prophylactically” use synchronized NIPPV to ensure the stability of their infants. In these three studies, the Star 500 or 950 was used to provide S-NIPPV. Newer generations of ventilators do not use the Graesby capsule. The inline flow sensors pose significant technical challenges when trying to interface with a nasal mask or nasal prongs and provide synchrony.

Barrington, et al. sought to determine whether S-NIPPV was better than NCPAP. They enrolled 54 infants (determined by power analysis) of <1251 gms birth weight (831 gms ± 139 gms) (26.3 ± 1.8 weeks gestational age) who were to be extubated before six weeks of age. Extubation criteria were FIO2 <0.35, fx<18, loading with aminophylline, and successful 12 hours on SIMV after the aminophylline load. Infants were evaluated for failure 72 hours post-extubation. Those randomized to the NCPAP arm were placed on +6 cm H2O. Those enrolled in the NIPPV arm were placed on fx=12, PEEP=6 cm H2O, and PIP=minimally 12 cm H2O. Failure criteria were PaCO2 >70 torr and FIO2 > 0.70. This study also continuously monitored for apnea events, and the failure criteria included >2 apneas requiring PPV in 24 hours or >6 apneas >20 seconds per day. Apnea was defined as bradycardia <100 beats per min. or acute desaturation to <80%. Mean age at extubation was 7.6 (9.7 days [range 1-40 days]). Four out of 27 in the NIPPV arm were extubation failures while 12 out of 27 in the NCPAP arm failed extubation. The authors concluded that the decreased rate of extubation failure was caused by decreased incidence of apnea and hypercarbia.

NIPPV has been shown to reduce asynchronous thoracoabdominal motion, perhaps as a result of reducing tube resistance and/or better stabilization of the chest wall.(5) This brings into question whether decreased PaCO2 is a reason for decreased failure or a marker for improved chest wall stability and improved synchrony.

This study noted no increase in abdominal distension compared to NCPAP and no evidence of gastric perforation. This issue was raised by Garland in 1985 and has been a caveat with NCPAP use ever since.(6)

In the discussion section, the authors comment that "the development of synchronized ventilators for the newborn infant presents a number of potential advantages for nasal ventilation. Thus positive pressure ventilator breaths will be delivered only after a respiratory effort by the infant, when the glottis is likely to be open, or after an apneic interval, the duration of which would depend on ventilator settings." This need for synchrony may easily be overlooked by the clinician, and must be considered when allocating resources in the NICU.

Friedlich, et al. compared nasopharyngeal CPAP to nasopharyngeal SIMV. Outcomes were measured 48 hours after extubation. Infants were eligible for the study with a birth weight of 500 gms to 1500 gms. Patients were stratified to 500-750 gms, 751-1000 gms, 1001-1250 gms, and 1251-1500 gms. Extubation readiness was SIMV rate = 12, PIP = 23 cm H2O, PEEP = 6, and FIO2 =0.40. Decision to extubate rested with the attending neonatologist.

Both groups had 3.0 Fr. silicone binasal prongs inserted. The initial post-extubation SIMV was set at 10 breaths per minute and adjusted based on the patient's clinical status. PIP was set to the pre-extubation PIP and adjusted as needed. Initial PEEP was set at 4-6 cm H2O. A long Ti=0.6 seconds was used to optimize alveolar recruitment. FIO2 was adjusted to keep the SaO2 92-95. The CPAP group had CPAP set and changed at the direction of the clinician. CPAP was weaned to +4 cm H2O before the prongs were removed.

Two or more of the following were considered a respiratory failure: pH =7.25 on two ABGs 30 minutes apart, a change in PaCO2 25% above the pre-extubation value, FIO2 =0.60 to maintain SaO2 92-95%, SIMV rate =20, PIP =26 cm H2O, PEEP =8 cm H2O, or apnea defined as HR <100 that did not resolve with stimulation or required PPV. No crossover was allowed in the study protocol. Once failure criteria were met, the study was terminated. The need for reintubation was left to the discretion of the clinician.

The authors determined that 55 patients would be necessary in each group to detect a minimum 50% reduction in post-extubation respiratory failure. The study was stopped after 41 patients were enrolled secondary to a statistically significant reduction in post-extubation failure in the SIMV group. One out of 22 in the SIMV group failed extubation. Seven out of 19 in the CPAP group failed extubation. The mean duration of therapy was 79 hrs for the N-SIMV and 51 hours for the NCPAP group. It is important to note that of the seven patients who failed the CPAP arm, only one required reintubation. The other six were "rescued" outside the study protocol with nasal-SIMV. No GI issues were noted in this study. No incidence of pulmonary air leak, upper airway injury, or cardiovascular effect was seen. These side effects have all been reported in the literature by many authors.

Khalaf, et al. enrolled infants =34 weeks gestation. Infants were stratified 500-749 gms, 750-999 gms and >1,000 gms. Their extubation criteria were PIP =16 cm H2O, PEEP =5 cm H2O, IMV 15 to 25, and FIO2 =0.35. PFTs were also done prior to extubation. Patients were required to have an aminophylline level =8 and a hematocrit =40. These study patients were evaluated at 72 hours after extubation. Infants randomized to CPAP were started on 4-6 cm H2O, PEEP. Infants who were randomized to NIPPV received N-SIMV at the same rate they were receiving prior to extubation. PIP was increased 2-4 cm H2O, PEEP was kept at =5 cm H2O, and FIO2 was titrated to keep SaO2 90-96%. Flow was kept at 8-10 L/min. The ventilator rate could be increased to 25 to maintain normal blood gases. Failure was defined as the need for reintubation. Failure was defined as pH <7.25, PaCO2 >60 torr, a single episode of apnea requiring PPV, frequent (>2-3/hour) apnea/bradycardia (cessation of breathing >20 seconds and HR <100) not responding to aminophylline, desaturations (<85%) =3 episodes per hour not responding to increased ventilatory settings or an increase in FIO2 to 1.00, or a PaO2 <50 torr despite an FIO2 of 1.00.

Thirty-four infants with a mean birth weight of 1,088 gms were randomized to NIPPV and 30 with a mean birth weight of 1,032 gms were randomized to NCPAP. The mean gestational age for both groups was 28 weeks. Before extubation, the mean airway pressure, FIO2, RAWE, and CDYN were similar in both groups. Thirty-two out of 34 infants in the NIPPV arm were successfully extubated compared to 18 out of 30 in the NCPAP arm. Two of the NCPAP failures were "rescued" by the use of NIPPV, although there was no crossover built into the study.

This is the only study of the three that looked at pulmonary function prior to extubation. The Bicore CP-100 was used to monitor RAWE (normal 35-70 cm H2O/L/sec and CDYN (normal 0.5-1.0 mL/kg/cm H2O). With a RAWE cut off =70 cm H2O), 10 out of 12 (NCPAP and NIPPV combined) were successfully extubated. Using a CDYN cut off =0.5, 33 out of 43 (NCPAP and NIPPV) were successfully extubated. By combining the two cut-off values, 8 out of 10 infants were successfully extubated. In infants with poor lung function (RAWE >70 cm H2O/L/s and CDYN <0.5 mL/kg/cm H2O), successful extubation was seen in 27 out of 29 infants in the NIPPV arm and only 15 out of 25 in the NCPAP arm.

When weight was controlled for at the time of extubation, the odds of successful extubation were 21.1 times higher in the NIPPV group.

The evidence in these studies strongly indicates that NIPPV should be the mode of choice for extubation. Most NICUs will not have the resources to put all their extubated patients on NIPPV. Allocation of resources to those patients with poor RAWE and CDYN would appear to make good sense. There is strong evidence here to change our standard of practice to include the use of NIPPV and increase the use of PFTs in the neonatal population.

References

1. Davis PG, Lemyre B, De Paoli AG. Nasal intermittent positive pressure ventilation (NIPPV) versus nasal continuous positive pressure ventilation (NCPAP) for preterm neonates after extubation, The Cochrane Library Issue 4, 2003.
2. Barrington KJ, Bull D, Finer NN. Randomised Trial of Nasal Synchronized Intermittent Mandatory Ventilation Compared with Continuous Positive Airway Pressure After Extubation of Very Low Birth Weight Infants, Pediatrics vol. 107 No, 4 April 2001 pp 638-641.
3. Friedlich P, Lecart C, Ramicone E, Chan L, Ramanathan R. A Randomized Trial of Nasopharyngeal-Synchronized Intermittent Mandatory Ventilation Versus Nasopharyngeal Continuous Positive Airway Pressure in Very Low Birth Weight Infants After Extubation, Journal of Perinatology (1999) 19(6) 413-418.
4. Khalaf MN, Brodsky N, Hurley J, Bhandari V. A Prospective Randomized, Controlled Trial Comparing Synchronized Nasal Intermittent Positive Pressure Ventilation Versus Nasal Continuous Positive Airway Pressure as Modes of Extubation, Pediatrics Vol. 108 No. 1 July 2001, pp 13-17.
5. Kiciman NM, Andréasson B, Bernstein G, Mannino FL, Rich W, Henderson C, Heldt GP. Thoracoabdominal motion in newborns during ventilation delivered by endotracheal tube or nasal prongs. Pediatr Pulmonol 1998; 25:175-181.
6. Garland JS, Nelson DB, Rice T, Neu J. Increased risk of gastrointestinal perforations in neonates mechanically ventilated with either a face mask or nasal prongs. Pediatrics 1985; 76:406-410.
   

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Children are curious by nature. Their desire to investigate new things is generally accomplished by touching, feeling, and climbing onto something unexplored. But when a child decides to eat or drink something potentially toxic, it is often too late to stop the serious effects that can accompany the mistake.

An 18-month-old was admitted to a community hospital following ingestion of approximately 10 mL of household lamp oil. Upon admission to the emergency room, the child was in respiratory distress, with grunting, nasal flaring, substernal retractions, and tachypnea. An albuterol aerosol was administered via mask. The SPO2 was 100% in room air following the aerosol. The patient rapidly became lethargic, with increasing respiratory distress, and was orally intubated by rapid sequence induction. The patient was sedated and paralyzed for transport.

The patient was transported to a children's hospital and admitted to the PICU. Upon arrival, mechanical ventilation was initiated at SIMV, volume control mode, frequency 25 bpm, PEEP +7, delivered tidal volume of 8cc/kg, pressure support 6cm H2O, and FIO2 of .65. EtCO2 and SPO2 were within normal limits. Chest radiograph revealed fluffy infiltrates bilaterally. The total respiratory rate continued to exceed 40 bpm. Pressure support levels were increased to 17 cm H2O, and frequency was decreased to 4 bpm as exhaled tidal volumes were monitored continuously. Respiratory rate remained in the 40s with exhaled tidal volumes measured at 6 cc/kg target range. Blood-tinged sputum was suctioned from the endotracheal tube.

The patient remained intubated and ventilated for 24 hours. Upon extubation, the patient was placed on 50% FIO2. The patient required hourly nasotracheal suctioning due to copious amounts of secretions and periods of desaturation. Six hours post extubation, BIPAP was instituted by mask at levels 10/5 cm H2O and 15 lpm oxygen bleed in. The patient was reintubated two hours after the initiation of BIPAP due to respiratory failure, with respiratory rate in excess of 100 bpm and desaturation (80% SPO2) requiring positive pressure ventilation. Following intubation, the chest radiograph presented with bilateral infiltrates. IPV was administered via endotracheal tube. Thick white secretions were suctioned from the endotracheal tube following treatment.

Eight hours following reintubation, FIO2 requirement continued to increase to 60%, with a PaO2/FIO2 ratio >200. Peak pressures during volume controlled SIMV rose to 36 cm H2O while on 7 cc/kg tidal volume, PEEP +10 cm H2O, rate 24 bpm. The patient was switched to pressure controlled ventilation: rate 24, PEEP +10 cm H2O, FIO2 60%, PC 24 cm H20. Measured exhaled tidal volumes were 6 cc/kg. IPV treatments were continued at Q4 hour intervals, and large amounts of white secretions were suctioned, as previously. Thirty-six hours following reintubation, ventilator settings were weaned, chest radiograph was improved, respiratory rate decreased to <50 bpm, and the patient was successfully extubated. The patient required oxygen and airway clearance for three days following extubation.
Hydrocarbon ingestion accounts for approximately 2% of all accidental poisonings in children less than six years of age. Lamp oil consists of petroleum distillates found in other products, such as gasoline, kerosene, paraffin, and mineral spirits. Lamp oil contains additional dyes, scents, and aroma-filled hydrocarbons (U.S. Consumer Product Safety Commission: 2001).

The unique property of lamp oil responsible for the acute onset of pulmonary aspiration is its viscosity. Lower viscosity fuel oils such as gasoline or kerosene are also highly volatile and dangerous to major organ systems, including the pulmonary, gastrointestinal, and the central nervous systems, as the oil is spread over mucosal surfaces. The most serious consequence of lamp oil ingestion is chemical pneumonitis, which can cause severe pulmonary injury and even death.

The various cases of hydrocarbon ingestion we reviewed suggest a similar onset of respiratory failure as described in this case report. Other cases suggest that the development of pulmonary infiltrates occurs as early as a few hours after the ingestion to as late as 24 hours following the ingestion. Acute reduction in hemoglobin caused by acute hemolysis is also a common finding. Fever and seizures may occur as secondary findings.

Treatment of hydrocarbon ingestion may require interventions such as oxygen, intubation, suctioning, mechanical ventilation, antibiotics, blood transfusion, airway clearance, or other serious modalities, including ECMO. The severity of the ingestion will dictate the type of treatment necessary for a complete recovery.

Reference
Hawkins B. Vanderbilt Center for Molecular Toxicology:1999 www.cdc.gov/mmwr/preview/mmwrhtml/00055332.htm.

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