The ability of paramedics to predict aspiration in patients undergoing prehospital rapid sequence intubation.

One of the purported benefits to invasive prehospital airway management is the prevention of aspiration; however, aspiration events may occur before the arrival of prehospital personnel. We explore the timing of aspiration in patients with severe traumatic brain injury (TBI) undergoing paramedic rapid sequence intubation (RSI). Severely head-injured (Glasgow Coma Scale [GCS] score 3-8) adults were prospectively enrolled into the San Diego Paramedic RSI Trial. As part of the prehospital data collection tool, paramedics prospectively assessed for clinical evidence of aspiration before RSI (pre-intubation), aspiration events occurring during RSI (peri-RSI), and regurgitation of vomitus or blood after intubation (post-intubation). Data were abstracted from work sheets used during the RSI procedure, a telephone debriefing by one of the principal investigators immediately after delivery of the patient, and San Diego County prehospital and trauma databases. The incidence of pre-intubation aspiration, peri-RSI aspiration, and post-intubation regurgitation of vomitus or blood were determined. Patients with and without pre-intubation aspiration were compared with regard to pre- and post-intubation hypoxia and the rate of aspiration pneumonia. Logistic regression was used to explore the association between pre-intubation aspiration and various demographic and clinical factors. The results showed that pre-intubation aspiration was noted by paramedics in 72/269 patients in whom complete data were available. Peri-RSI aspiration was reported in one patient; there were no reported cases of post-intubation regurgitation of vomitus or blood. Patients in the pre-intubation aspiration group required more intubation attempts, had a higher incidence of desaturations and lower pre- and post-intubation SaO(2) values, and were more frequently diagnosed with aspiration pneumonia. Pre-intubation aspiration was associated with severe TBI, GCS score of 3, younger age, and the absence of alcohol intoxication despite controlling for age, gender, GCS, Head AIS (Abbreviated Injury Score), and serum ethanol. It is concluded that paramedics seem to be able to accurately assess for aspiration in patients undergoing prehospital RSI. The vast majority of aspiration events seem to occur before the arrival of prehospital personnel. Alteration in consciousness from TBI may carry a higher risk of aspiration than with other causes, such as alcohol intoxication.

The association between field Glasgow Coma Scale score and outcome in patients undergoing paramedic rapid sequence intubation.

Early intubation is standard for treating severe traumatic brain injury (TBI). Aeromedical crews and select paramedic agencies use rapid sequence intubation (RSI) to facilitate intubation after TBI, with Glasgow Coma Scale (GCS) score commonly used as a screening tool. To explore the association between paramedic GCS and outcome in patients with TBI undergoing prehospital RSI, paramedics prospectively enrolled adult major trauma victims with GCS 3-8 and clinical suspicion for head trauma to undergo succinylcholine-assisted intubation as part of the San Diego Paramedic RSI Trial. The following data were abstracted from paramedic debriefing interviews and the county trauma registry: demographics, mechanism, vital signs including GCS score, clinical evidence of aspiration before RSI, arrival laboratory values, hospital course, and outcome. Paramedic GCS calculations were confirmed during debriefing interviews. Patients were stratified by GCS score, with chi-square and receiver-operator-curve (ROC) analysis used to explore the relationship between GCS and hypoxia, head injury severity, aspiration, intensive care unit (ICU) length of stay, and outcome. Cohort analysis was used to explore potential reasons for early extubation and discharge from the ICU in some patients. A total of 412 patients were included in this analysis. A total of 81 patients (20%) were extubated and discharged from the ICU in 48 h or less; these patients had higher pre-RSI oxygen saturation (SaO(2)) values and higher arrival serum ethanol levels. Paramedic and physician GCS calculations had high agreement (kappa=0.995). A statistically significant relationship was observed between GCS score and Head Abbreviated Injury Score (AIS), survival, and pre-RSI SaO(2) values. However, ROC analysis revealed a limited ability of GCS to predict the presence of severe TBI, injury severity, desaturation, aspiration, ICU length of stay, or ultimate survival. In conclusion, paramedics seem to accurately calculate GCS values before prehospital RSI. Although a relationship between paramedic GCS and outcome exists, the ability to predict the severity of injury, airway-related complications, ICU length of stay, and overall survival is limited using this single variable. Other factors should be considered to screen TBI patients for prehospital RSI.

Ventilation patterns in patients with severe traumatic brain injury following paramedic rapid sequence intubation.

INTRODUCTION: Inadvertent hyperventilation has been documented during aeromedical transports but has not been studied following paramedic rapid sequence intubation (RSI). The San Diego Paramedic RSI Trial was designed to study the impact of paramedic RSI on outcome in patients with severe head injury. This analysis explores ventilation patterns in a cohort of trial patients undergoing end-tidal CO2 (ETCO2) monitoring. METHODS: Adult patients with severe head injury (Glasgow Coma Score: 3-8) unable to be intubated without RSI were prospectively enrolled in the trial. Midazolam and succinylcholine were used for RSI; rocuronium was administered following tube confirmation. Standardized ventilation protocols were used by most paramedics; however, one agency instituted ETCO2 monitoring during the second trial year, with paramedics instructed to target ETCO2 values of 30 to 35 mmHg. The incidence and duration of inadvertent hyperventilation (ETCO2: <30 mmHg) and severe hyperventilation (ETCO2: <25 mmHg) were explored for patients undergoing ETCO2 monitoring. The initial, final, minimum, and maximum values for ETCO2 and the maximum and minimum ventilatory rate values were also calculated using descriptive statistics (95% confidence interval). The pattern of ETCO2 values over time and distribution of recorded ventilatory rate values were explored graphically. RESULTS: A total of 76 trial patients had adequate ETCO2 data for this analysis. The mean values for initial, final, maximum, and minimum ETCO2 were 40.8 (range: 37.5-44.2), 28.4 (range: 25.4-31.4), 45.1 (range: 41.4-48.8), and 23.5 mmHg (range: 21.4-25.5), respectively. The mean maximum and minimum ventilatory rate values were 36.0/minute (range: 33.5-38.5) and 12.8/minute (range: 11.9-13.7), respectively. ETCO2 values less than 30 and 25 mmHg were documented in 79% and 59% of patients, respectively, with mean durations of 485 (range: 378-592) and 390 seconds (range: 285-494). CONCLUSION: Inadvertent hyperventilation is common following paramedic RSI, despite ETCO2 monitoring and target parameters.

The impact of hypoxia and hyperventilation on outcome after paramedic rapid sequence intubation of severely head-injured patients.

BACKGROUND: An increase in mortality has been documented in association with paramedic rapid sequence intubation (RSI) of severely head-injured patients. This analysis explores the impact of hypoxia and hyperventilation on outcome. METHODS: Adult severely head-injured patients (Glasgow Coma Scale score of 3-8) unable to be intubated without neuromuscular blockade underwent paramedic RSI using midazolam and succinylcholine; rocuronium was administered after confirmation of tube position. Standard ventilation parameters were used for most patients; however, one agency instituted use of digital end-tidal carbon dioxide (ETCO2) and oxygen saturation (Spo2) monitoring during the trial. Each patient undergoing digital ETCO2/Spo2 monitoring was matched to three historical nonintubated controls on the basis of age, gender, mechanism, and Abbreviated Injury Scale scores for each of six body regions. Logistic regression was used to explore the impact of oxygen desaturation during laryngoscopy and postintubation hypocapnia and hypoxia on outcome. The relationship between hypocapnia and ventilatory rate was explored using linear regression and univariate analysis. In addition, trial patients and controls were compared with regard to mortality and the incidence of "good outcomes" using an odds ratio analysis. RESULTS: Of the 426 trial patients, a total of 59 had complete ETCO2/Spo2 monitoring data; these were matched to 177 controls. Logistic regression revealed an association between the lowest ETCO2 value and final ETCO2 value and mortality. Matched-controls analysis confirmed an association between hypocapnia and mortality. A statistically significant association between ventilatory rate and ETCO2 value was observed (r = -0.13, p < 0.0001); the median ventilatory rate associated with the lowest recorded ETCO2 value was significantly higher than for all other ETCO2 values (27 mm Hg vs. 19 mm Hg, p < 0.0001). In addition, profound desaturations during RSI and hypoxia after intubation were associated with higher mortality than matched controls. Overall mortality was 41% for trial patients versus 22% for matched controls (odds ratio, 2.51; 95% confidence interval, 1.33-4.72; p = 0.004). CONCLUSIONS: Hyperventilation and severe hypoxia during paramedic RSI are associated with an increase in mortality.

The use of quantitative end-tidal capnometry to avoid inadvertent severe hyperventilation in patients with head injury after paramedic rapid sequence intubation.

BACKGROUND: This study aimed to determine whether field end-tidal carbon dioxide CO2 (ETCO2) monitoring decreases inadvertent severe hyperventilation after paramedic rapid sequence intubation. METHODS: Data were collected prospectively as part of the San Diego Paramedic Rapid Sequence Intubation Trial, which enrolled adults with severe head injuries (Glasgow Coma Score, 3-8) that could not be intubated without neuromuscular blockade. After preoxygenation, the patients underwent rapid sequence intubation using midazolam and succinylcholine. A maximum of three intubation attempts were allowed before Combitube insertion was mandated. Tube confirmation was accomplished by physical examination, qualitative capnometry, pulse oximetry, and syringe aspiration. Standard ventilation parameters (tidal volume, 800 mL; 12 breaths/minute) were taught. One agency used portable ETCO2 monitors, with ventilation modified to target ETCO2 values of 30 to 35 mm Hg. Trial patients transported by aeromedical crews also underwent ETCO2 monitoring. The primary outcome measure was the incidence of inadvertent severe hyperventilation, defined as arterial blood gas partial pressure of CO2 (pCO2) of less than 25 mm Hg at arrival, for patients with and those without ETCO2 monitoring. These groups also were compared in terms of age, gender, clinical presentation, Abbreviated Injury Score, Injury Severity Score, arrival arterial blood gas data, and survival. RESULTS: The study enrolled 426 patients and administered neuromuscular blocking agents to 418 patients. Endotracheal intubation was successful for 355 of these patients (85.2%). Another 58 patients (13.6%) underwent Combitube insertion. For 291 successfully intubated patients, arrival pCO2 values were documented, with continuous ETCO2 monitoring performed for 144 of these patients (49.4%). Patients with ETCO2 monitoring had a lower incidence of inadvertent severe hyperventilation than those without ETCO2 monitoring (5.6% vs. 13.4%; odds ratio, 2.64; 95% confidence interval, 1.12-6.20; p = 0.035). There were no significant differences in terms of age, gender, clinical presentation, Abbreviated Injury Score, Injury Severity Score, arrival partial pressure of oxygen (PO2) and pH, or survival. The patients in both groups with severe hyperventilation had a significantly higher mortality rate than the patients without hyperventilation (56 vs. 30%; odds ratio, 2.9; 95% confidence interval, 1.3-6.6; p = 0.016), which could not be explained solely on the basis of their injuries. CONCLUSIONS: The use of ETCO2 monitoring is associated with a decrease in inadvertent severe hyperventilation.

Air medical transport of severely head-injured patients undergoing paramedic rapid sequence intubation.

INTRODUCTION: The San Diego Paramedic Rapid Sequence Intubation (RSI) Trial documented an increase in mortality with paramedic RSI of patients with severe traumatic brain injury. This analysis explores the impact of air medical transport of trial patients on outcome. METHODS: Adult trauma victims with severe traumatic brain injury (Glasgow Coma Scale score of 3 to 8) were prospectively enrolled. Paramedics performed RSI using midazolam and succinylcholine; air medical crews could be called at the discretion of ground paramedics, generally for anticipated prolonged transports. Patients were matched to historical controls using the following parameters: age, gender, mechanism, injury of severity score, and abbreviated injury scale scores for each body system. Patients transported by air and ground were compared with regard to demographics, clinical parameters, vital signs, arterial blood gas data, and outcome. RESULTS: A total of 336 patients were included (79 air medical and 257 ground transports). No significant differences arose between the groups with regard to demographic, clinical, vital sign, and arterial blood gas data. Air medical patients had decreased mortality (28% vs 31%, OR 0.9), and ground patients had increased mortality versus matched controls (33% vs 22%, OR 1.8). Discordant groups analysis revealed a statistically significant effect of transport personnel on outcome (P=.009). Neither advanced procedures nor the use of mannitol accounted for the improved outcomes; air medical crews used capnometry to guide ventilation on all study patients. CONCLUSION: Air medical transport of severely head-injured patients undergoing paramedic RSI was associated with improved outcomes. Improved ventilation by capnometry may account for part of these improvements.

Incidence of transient hypoxia and pulse rate reactivity during paramedic rapid sequence intubation.

STUDY OBJECTIVE: We determine the incidence of desaturation and pulse rate reactivity during paramedic rapid sequence intubation of patients with severe head injuries (Glasgow Coma Scale score

Paramedic-administered neuromuscular blockade improves prehospital intubation success in severely head-injured patients.

BACKGROUND: The purpose of this study was to evaluate the effect of paramedic-administered neuromuscular blocking agents as part of a rapid-sequence intubation (RSI) protocol on successful intubation of severely head-injured patients in a large, urban prehospital system. METHODS: Adult head-injured patients were prospectively enrolled over 1 year using these inclusion criteria: Glasgow Coma Scale (GCS) score of 3 to 8, transport time > 10 minutes, and inability to intubate without RSI. Midazolam and succinylcholine were administered before laryngoscopy; rocuronium was given after tube placement was confirmed using capnometry, syringe aspiration, and pulse oximetry. The Combitube was used as a salvage airway device. All adult trauma victims with a GCS score of 3 to 8 were identified during the first 12 months of the study as the trial cohort and from the preceding 12 months as the control cohort. The trial and control cohorts were compared with regard to demographic data, mechanism of injury, initial vital signs, and GCS scores. The primary outcome measure was intubation success, defined as insertion of either an endotracheal tube or a Combitube, with patients stratified by GCS score. RESULTS: The trial cohort (n = 249) and control cohort (n = 189) were similar with regard to demographic data, mechanism of injury, and initial vital signs and GCS scores. Intubation success rates increased significantly during the trial period for all patients and when stratified into GCS score of 3 and GCS score of 4 to 8. The percentage of patients intubated without neuromuscular blocking agents actually increased during the trial period. Although the number of intubations by helicopter flight crews decreased during the trial, the overall use of aeromedical resources did not change. CONCLUSION: Paramedic-administered neuromuscular blockade as part of an RSI protocol improves intubation success in a large, urban prehospital system.

The Combitube as a salvage airway device for paramedic rapid sequence intubation.

STUDY OBJECTIVE: The safety of out-of-hospital rapid sequence intubation depends on a reliable strategy when orotracheal intubation is unsuccessful. Here we describe our experience with the Combitube (esophageal-tracheal twin-lumen airway device) as a salvage airway device for paramedic rapid sequence intubation. METHODS: The San Diego Paramedic Rapid Sequence Intubation Trial was performed to assess the effect of paramedic rapid sequence intubation on outcome in severely head-injured patients. Adults with severe head trauma (Glasgow Coma Scale score 3 to 8) who were unable to be intubated without medications were enrolled. Midazolam and succinylcholine were administered, and paramedics were allowed a maximum of 3 attempts at orotracheal intubation. If the attempts were unsuccessful, Combitube insertion was mandated. After confirmation of tube position, rocuronium was given and standard ventilation protocols were used. The primary outcome measure for this analysis was the success rate for Combitube insertion after unsuccessful orotracheal intubation. In addition, Combitube insertion and orotracheal intubation patients were compared with regard to demographic, clinical, and outcome data. RESULTS: A total of 426 patients were enrolled in the trial, with 420 meeting inclusion criteria for this analysis. Orotracheal intubation was successful in 355 (84.5%) of 420; Combitube insertion was successful in 58 (95.1%) of 61 attempts, with no reported complications. Patients undergoing Combitube insertion had higher Face Abbreviated Injury Scale scores and were more likely to have oropharyngeal blood or vomitus. Arrival Pco(2) values were higher, and arrival Po(2) values were lower but still supranormal in patients undergoing Combitube insertion. There were no mortality differences between patients undergoing Combitube insertion and those undergoing orotracheal intubation. CONCLUSION: The Combitube can be an effective salvage airway device for paramedic rapid sequence intubation in an urban/suburban, high-volume emergency medical services system with paramedics who are experienced in Combitube placement and with stringent protocols for its use. The device should be tested in other sizes and types of systems and under less medical scrutiny than was used in this study.

The effect of paramedic rapid sequence intubation on outcome in patients with severe traumatic brain injury.

OBJECTIVE: To evaluate the effect of paramedic rapid sequence intubation (RSI) on outcome in patients with severe traumatic brain injury. METHODS: Adult major trauma victims were prospectively enrolled over two years using the following inclusion criteria: Glasgow Coma Scale (GCS) 3-8, suspected head injury by mechanism or physical examination, transport time > 10," and inability to intubate without RSI. Midazolam and succinylcholine were administered before laryngoscopy; rocuronium was given after tube placement was confirmed using physical examination, capnometry, syringe aspiration, and pulse oximetry. The Combitube was used as a salvage airway device. For this analysis, trial patients were excluded for absence of a head injury (Head/Neck AIS score < 2), failure to fulfill major trauma outcome study criteria, unsuccessful intubation or Combitube insertion, or death in the field or in the resuscitation suite within 30" of arrival. Each study patient was hand matched to three nonintubated historical controls from our trauma registry using the following parameters: age, sex, mechanism of injury, trauma center, and AIS score for each body system. Controls were excluded for Head/Neck AIS defined by a c-spine injury or death in the field or in the resuscitation suite within 30" of arrival. chi 2, odds ratios, and logistic regression were used to investigate the impact of RSI on the primary outcome measures of mortality and incidence of a "good outcome," defined as discharge to home, rehabilitation, psychiatric facility, jail, or signing out against medical advice. RESULTS: A total of 209 trial patients were hand matched to 627 controls. The groups were similar with regard to all matching parameters, admission vital signs, frequency of specific head injury diagnoses, and incidence of invasive procedures. Mortality was significantly increased in the trial cohort versus controls for all patients (33.0% versus 24.2%, p < 0.05) and in those with Head/Neck AIS scores of 3 or greater (41.1% versus 30.3%, p < 0.05). The incidence of a "good outcome" was lower in the trial cohort versus controls (45.5% versus 57.9%, p < 0.01). Factors that may have contributed to the increase in mortality include transient hypoxia, inadvertent hyperventilation, and longer scene times associated with the RSI procedure. CONCLUSION: Paramedic RSI protocols to facilitate intubation of head-injured patients were associated with an increase in mortality and decrease in good outcomes versus matched historical controls.

Paramedic-performed rapid sequence intubation of patients with severe head injuries.

STUDY OBJECTIVE: We evaluate the ability of paramedic rapid sequence intubation (RSI) to facilitate intubation of patients with severe head injuries in an urban out-of-hospital system. METHODS: Adult patients with head injuries were prospectively enrolled over a 1-year period by using the following inclusion criteria: Glasgow Coma Scale score of 3 to 8, transport time of greater than 10 minutes, and inability to intubate without RSI. Midazolam and succinylcholine were administered before laryngoscopy, and rocuronium was given after tube placement was confirmed by means of capnometry, syringe aspiration, and pulse oximetry. The Combitube was used as a salvage airway device. Outcome measures included intubation success rates, preintubation and postintubation oxygen saturation values, arrival arterial blood gas values, and total out-of-hospital times for patients intubated en route versus on scene. RESULTS: Of 114 enrolled patients, 96 (84.2%) underwent successful endotracheal intubation, and 17 (14.9%) underwent Combitube intubation, with only 1 (0.9%) airway failure. There were no unrecognized esophageal intubations. On arrival at the trauma center, median oxygen saturation was 99%, mean arrival PO2 was 307 mm Hg, and mean arrival PCO2 was 35.8 mm Hg. Total out-of-hospital times were higher when RSI was performed on scene (26 versus 13 minutes). CONCLUSION: Paramedics can use RSI protocols that include neuromuscular blocking and sedative agents to facilitate intubation of patients with head injuries.