A performance comparison of the most commonly used minimally invasive monitors of cardiac output.

BACKGROUND: Shock is common in critically ill and injured patients. Survival during shock is highly dependent on rapid restoration of tissue oxygenation with therapeutic goals based on cardiac output (CO) optimization. Despite the clinical availability of numerous minimally invasive monitors of CO, limited supporting performance data are available. METHODS: Following approval of the University of Saskatchewan Animal Research Ethics Board, we assessed the performance and trending ability of PiCCOplus™, FloTrac™, and CardioQ-ODM™ across a range of CO states in pigs. In addition, we assessed the ability of invasive mean arterial blood pressure (iMAP) to follow changes in CO using a periaortic transit-time flow probe as the reference method. Statistical analysis was performed with function-fail, bias and precision, percent error, and linear regression at all flow, low-flow (> 1 standard deviation [SD] below the mean), and high-flow (> 1 SD above the mean) CO conditions. RESULTS: We made a total of 116,957 paired CO measurements. The non-invasive CO monitors often failed to provide a CO value (CardioQ-ODM: 40.6% failed measurements; 99% confidence interval [CI], 38.5 to 42.6; FloTrac: 9.6% failed measurements; 99% CI, 8.7 to 10.5; PiCCOplus: 4.7% failed measurements; 99% CI, 4.5 to 4.9; all comparisons, P < 0.001). The invasive mean arterial pressure provided zero failures, failing less often than any of the tested CO monitors (all comparisons, P < 0.001). The PiCCOplus was most interchangeable with the flow probe at all flow states: PiCCOplus (20% error; 99% CI, 19 to 22), CardioQ-ODM (25% error; 99% CI, 23 to 27), FloTrac (34% error; 99% CI, 32 to 38) (all comparisons, P < 0.001). At low-flow states, CardioQ-ODM (43% error; 99% CI, 32 to 63) and Flotrac (45% error; 99% CI, 33 to 70) had similar interchangeability (P = 0.07), both superior to PiCCOplus (48% error; 99% CI, 42 to 60) (P < 0.001). Regarding CO trending, the CardioQ-ODM (correlation coefficient, 0.82; 99% CI, 0.81 to 0.83) was statistically superior to other monitors including iMAP, but at low flows iMAP (correlation coefficient, 0.58; 99% CI, 0.58 to 0.60) was superior to all minimally invasive CO monitors (all comparisons P < 0.001). CONCLUSIONS: None of the minimally invasive monitors of CO performed well at all tested flows. Invasive mean arterial blood pressure most closely tracked CO change at critical flow states.

RéSUMé: CONTEXTE: L'état de choc est fréquent chez les patients blessés et en urgence absolue. La survie pendant le choc dépend fortement de la restauration rapide de l'oxygénation tissulaire avec des objectifs thérapeutiques basés sur l'optimisation du débit cardiaque (DC). Malgré la disponibilité clinique de nombreux moniteurs minimalement invasifs du DC, il n'existe que des données limitées sur leur performance pour appuyer leur utilisation. MéTHODE: À la suite de l'approbation du comité d'éthique de la recherche animale de l'Université de la Saskatchewan, nous avons évalué la performance et la capacité de suivi des tendances des appareils PiCCOplus™, FloTrac™ et CardioQ-ODM™ sur une vaste gamme d'état de DC chez des cochons. Nous avons également évalué la capacité de la tension artérielle moyenne invasive (iMAP) à suivre les changements de DC en utilisant une sonde périaortique de débit basée sur le temps de transit comme méthode de référence. L'analyse statistique a été réalisée avec fonction-échec, biais et précision, pourcentage d'erreur et régression linéaire à des conditions de DC de tous les débits, de faible débit (> 1 écart-type [ET] au-dessous de la moyenne) et de débit élevé (> 1 ET au-dessus de la moyenne). RéSULTATS: Nous avons effectué un total de 116 957 mesures de DC appariées. Les moniteurs non invasifs de la DC n'ont souvent pas réussi à fournir une valeur de DC (CardioQ-ODM : 40,6% de mesures échouées; intervalle de confiance [IC] de 99 %, 38,5 à 42,6; FloTrac : 9,6 % de mesures échouées; IC 99 %, 8,7 à 10,5; PiCCOplus : 4,7 % de mesures échouées; IC 99 %, 4,5 à 4,9; toutes les comparaisons, P < 0,001). La tension artérielle moyenne invasive n'a fourni aucun échec plus souvent que n'importe lequel des moniteurs de DC testés (toutes les comparaisons, P < 0,001). Le PiCCOplus était le plus interchangeable avec la sonde de débit à tous les états de débit : PiCCOplus (erreur de 20 %; IC 99 %, 19 à 22), CardioQ-ODM (erreur de 25 %; IC 99 %, 23 à 27), FloTrac (erreur de 34 %; IC 99 %, 32 à 38) (toutes les comparaisons, P < 0,001). Aux états de débit faible, les moniteurs CardioQ-ODM (erreur de 43 %; IC 99 %, 32 à 63) et FloTrac (erreur de 45 %; IC 99 %, 33 à 70) présentaient une interchangeabilité similaire (P = 0,07), tous deux supérieurs au PiCCOplus (erreur de 48 %; IC 99 %, 42 à 60) (P < 0,001). En ce qui concerne le suivi des tendances de DC, le CardioQ-ODM (coefficient de corrélation, 0,82; IC 99 %, 0,81 à 0,83) était statistiquement supérieur aux autres moniteurs, y compris au iMAP, mais à faibles débits, l'iMAP (coefficient de corrélation, 0,58; IC 99 %, 0,58 à 0,60) était supérieure à tous les moniteurs de DC minimalement invasifs (toutes les comparaisons, P < 0,001). CONCLUSION: Aucun des moniteurs de DC minimalement invasif n'a donné de bons résultats à tous les débits testés. La tension artérielle moyenne invasive était le moniteur qui a suivi de plus près les changements de DC dans des états critiques de débit.

Two children with extra-nodal Mycobacterium avium complex infection.

Mycobacterium avium complex (MAC) is usually considered an opportunistic organism, which infects immunocompromised children or those with structural airway abnormalities. We present two cases of MAC infection affecting immune competent children, likely from hot tubs with primary involvement of pulmonary and urinary systems. These cases highlight the importance of asking about hot tub use in immune competent children with suspected or confirmed MAC infections.

Applying vacuum to accomplish reduced wound infections in laparoscopic pediatric surgery.

INTRODUCTION: The prevention of surgical site infections has received little attention in pediatric surgery. Negative pressure wound therapy is used to treat complex wounds. We hypothesized that this principle could reduce wound infection rates following laparoscopic surgery. We tested this in a randomized controlled trial. MATERIALS AND METHODS: We randomized pediatric patients with an umbilical port site to a standard dressing or a vacuum dressing. The dressings were removed 48h after surgery. A nurse blinded for the treatment inspected the umbilical wound between post-operative days 7-10 for infection. Data comparison was performed using a Fisher exact test with p<0.05 defined as significant. RESULTS: We recruited 90 patients over 2 years and randomized 44 to the vacuum dressing arm and 42 to the control arm. We observed a 2.8% (n=1/35) infection rate in the vacuum dressing group and 3.3% (n=1/30) in the control group (p=1.0). DISCUSSION: We ended our study early when an interim analysis showed an impractical number of patients would be required to achieve sufficient power. We did not find a significant difference between the control and vacuum dressings in reducing post-operative wound infections. LEVEL OF EVIDENCE: 3.

Single incision laparoscopic surgery in Canadian children.

As minimally invasive surgery progresses, there have been attempts to modify the technique to minimize both the number and visibility of incisions. These newer techniques are known by multiple acronyms, including single incision laparoscopic surgery (SILS). The SILS technique has gained popularity in the United States, particularly owing to its perceived improved cosmesis. The SILS technique has been primarily used in adults, and the number of pediatric publications on the topic is underwhelming. We have begun to evaluate SILS at our centre to determine its applicability in both a Canadian and pediatric practice, and this commentary discusses our initial application of the procedure.

Operative innovation to the "Nuss" procedure for pectus excavatum: operative and functional effects.

BACKGROUND: The "Nuss" procedure for repair of pectus excavatum is performed with increasing frequency worldwide. We describe a technique of performing relaxing or "kerf" incisions along the cartilaginous ribs at the point of maximal chest wall concavity to facilitate retrosternal dissection and to reduce chest wall tension. The effects on operative parameters and long-term changes in cardiopulmonary function and appearance were evaluated prospectively. METHODS: Thirty patients underwent a Nuss procedure for the period from 2001 to 2004. Fifteen patients underwent a modified Nuss (MN) with sternocostal "relaxing" incisions, and these were compared to 15 patients undergoing a standard Nuss (SN). Data were prospectively gathered and included the number of relaxing incisions, bar number, blood loss, duration of epidural analgesia, number of days to discharge, and preoperative and postoperative cardiopulmonary function measures. RESULTS: The average Haller index of the SN group was 3.9 +/- 0.7 vs MN group index of 4.6 +/- 1.6 (P < .05). The median number of relaxing incisions in the study group was 4.0 +/- 0.7 (range 3 - 8). There were no significant differences between the study groups in any of the operative parameters analyzed, including blood loss, days of epidural requirements or days to reach functional independence. Nor were there differences in the improvement in subjective appearance, complications, pulmonary function, cardiac output at rest, oxygen transport or minute ventilation at maximal exercise. Subjectively, bar positioning and the intraoperative visualization was easier with the relaxing incisions. CONCLUSIONS: The addition of sternocostal relaxing incisions to the standard Nuss procedure appears to facilitate retrosternal dissection and bar placement, but no changes in long-term function or cosmesis were noted. The use of relaxing incisions appears to be safe and may facilitate operative visualization of retrosternal structures.

A multiinstitutional review of central venous line complications: retained intravascular fragments.

BACKGROUND: There have been many reports of complications of central venous lines in children but limited discussion of the specific problem of retained intravascular fragments after attempted removal. We report on a series of 6 patients from 2 tertiary pediatric hospitals that had intravascular segments of long-term central venous lines that could not be removed and so were left in situ. METHODS: We conducted a retrospective multiinstitutional review of long-term central venous lines (Broviacs, Port-A-Caths, and Hickmans) removed in the operating room with a focused chart review and prospective follow-up of those patients that had a failed attempt at removal. RESULTS: A total of 299 central venous lines were removed with 6 patients identified as having fragments of lines left behind (2%). The lines had been in place for an average of 37 +/- 12 months. The average follow-up period is now 5.4 +/- 3.9 years; none of the patients have developed any symptoms, evidence of thrombus, infection, or catheter migration. CONCLUSION: Given the 2% incidence rate, the issue of managing a stuck long-term central venous line will face most individuals who place these lines. We have demonstrated that simply ligating the catheter and leaving the fragment in place appears to be a safe option with minimal risk to the patient.

Intussusception associated with a Meckel's diverticulum and a duplication cyst.

Intussusception is a frequent cause for bowel obstructions and pediatric surgical consults. First described by Barbette in 1674, the etiology and treatment of intussusception has undergone several revisions for the last 300 years. Currently, we understand most intussusceptions in young children to be of idiopathic in nature with the incidence of pathologic lead points increasing with the age of the child. Although both Meckel's diverticulum and duplication cysts have both been reported numerous times in the past as a source of a lead point, we report, to our knowledge, the only case of both found in a child requiring operative reduction.

Routine pathological evaluation of tissue from inguinal hernias in children is unnecessary.

INTRODUCTION: Because unexpected disease is rare in a child's inguinal hernia sac we decided to investigate the cost of routine pathological evaluation of inguinal hernial sacs in children and the incidence of clinically significant pathological findings. METHODS: We searched the health records at the University Hospital, Saskatoon, for patients under 20 years of age who had inguinal hernia repair between 1988 and 1997. For records noting pathology findings of duct-like structures, the operative reports and histology slides were reviewed. Specimens were immunostained for muscle-specific actin. The cost of pathological evaluation was estimated using a provincial physician-billing schedule. RESULTS: During the study period, there were 488 inguinal hernia repairs in 371 patients under 20 years of age. Of these, 456 (93.4%) specimens were evaluated microscopically. There were 4 (0.88%) cases with unexpected findings diagnosed as epididymis at a cost of Can dollar 6988/case. CONCLUSION: The routine histologic evaluation of inguinal hernia sacs in children is an unnecessary expense and should be reserved for select cases at the discretion of the surgeon.