Effects of intensivist coverage in a post-anaesthesia care unit on surgical patients' case mix and characteristics of the intensive care unit

There is an increasing demand for critical care, which can lead to capacity limitations in the intensive care unit (ICU). These limitations can cause a delay in the admission of patients from emergency departments and the need to postpone elective surgery [1] potentially leading to increased morbidity and mortality [2]. Furthermore, in a fee-for-service system at fixed prices, as is the German Diagnosis Related Group System (G-DRG), prolonged process times and internal cues lead to hospitals having to bear higher costs at equal revenue making them less profitable. On the other hand, DRGs induce the implementation of goal oriented treatment and support discussion of therapeutic aims and quality in patient treatment [3, 4]. For hospitals and their staff the challenge is to optimize clinical processes and to optimize the effectiveness of treatment in regard to patient´s outcome.

Operating theatres and the intensive care units are very costly areas of a hospital, so it seems advisable to look at these areas closely [5]. Hospitals are forced to develop new and innovative strategies to address capacity restraints, improve throughput without a large amount of unoccupied beds in the intensive care unit. A decrease in quality of care or premature discharge of the patients from the intensive care unit, which negatively influences mortality [6], must be avoided.

Most major hospitals deliver different levels of intensive care [7]. Several studies have focused on "ICU-appropriateness" issues by retrospective analysis of qualitative ICU-bed utilization. The difficulty is a stratification between low-risk and high-risk patient-days using the Therapeutic Intervention Scoring System (TISS) categories [8] or specifically developed indices of level of care defined by the severity of organ failures [9] or by intensive care interventions [10]. This approach to defining the level of care is helpful in planning which level of care is appropriate for the individual patient, but does not solve the problem of restricted availability of ICU beds for emergency admissions, for example.

When there is no reserve ICU-capacity, intensivists select one of several less suitable options for new patients [11], each having individual risks for the patient. These options include interhospital transfers, initiation of treatment in the emergency department, trial of standard care in a low-acuity ward, cancellation of surgery and early discharge from ICU after triage [12]. Several studies have shown that early or night time discharge from the ICU is associated with higher ICU readmission rates, longer hospital length of stay and increased mortality [13, 14]. Some authors describe the transferral to a post anaesthesia care unit (PACU) as an unfavourable option, since equipment, expertise and staffing levels in the PACU are different from the ICU [11].

A possible solution to this problem might be the inclusion of the PACU in the process of distribution of patients to the different levels of intensive care. By staffing the PACU with intensive care staff 24 hours a day, patients can be treated at any time with the same equipment and expertise as in the ICU. The difference is the limitation of the length of treatment to 24 hours and the manpower used in the PACU for treatment, which is less, compared to the ICU. Besides a change of staffing in the PACU, definitions of admission and discharge criteria, which include the maximum duration of stay, were introduced. These admission criteria are used to overcome organizational barriers, as an alternative to routine admission to intensive care after certain types of surgery or trauma. The intention of the intensivist coverage is not an expansion of ICU-capacities, but the provision of high-quality intensive care for all patients without delay or postponement of elective surgery due to a lack of ICU-beds.

The economic aspects for the whole hospital of the introduction of PACU, as an alternative area to treat patients after major surgery, trauma or emergency admissions are not well investigated. There is also some evidence that treatment of post-surgery patients in the PACU is superior to treatment in conventional ICUs. Responsible for this effect might be the early goal-oriented therapy in the PACU and the clinical focus on the fast recovery of postoperative patients [15].

The aim of this study is to evaluate the effect on the structure of ICU-patients and to demonstrate the economic effect of the staffing of a PACU with an around-the-clock intensivist coverage on the hospital revenue for surgical patients of a university hospital.

The data protection officer of the hospital approved the collection of the data. The study, analysis and publication were approved by the local ethics committee of the hospital (EA1/314/11), which also waived individual patient consent, due to the retrospective nature of the study and the anonymous structure of the data.

The data of 51,090 patients, who underwent surgery as in-patients in the time period between 1 January 2008 and 30 April 2011 were evaluated. Of these patients, 3,317 were treated in the PACU for more than two hours. During this time period, 5,969 patients were treated in the ICU of the department of anaesthesiology and operative intensive care.

The results of our study show that the implementation of PACU with a 24-hour intensive care physician can influence the patient structure of the intensive care unit and can be beneficial for the hospital in terms of better management of resources. The fraction of long-term patients in the ICU increased. The patients in need of short-term intensive care up to 24 hours were treated in the PACU, creating resources in the intensive care unit. The more efficient short-term treatment in the PACU and the efficient allocation of capacity for long-term ICU-treatment in the ICU may result in an overall increase of the CM per bed per day for all surgical patients.

Several studies have focussed on the concept of "fast-track" treatment of patients after major abdominal or cardiac surgery [15, 17‐19], which includes an optimal preoperative assessment and preparation of the patient, optimal choice of anaesthetics, techniques and prophylactic drugs to minimize the impact of surgery and to maintain and recover optimal organ function after surgery. The objective of these concepts is the reduction of length of stay in the ICU, and improvement of outcomes for patients. Most of these protocols, especially for cardiac surgery patients, have been implemented in the ICU. Ender and co-workers [15] were able to demonstrate that patients after cardiac surgery fast-track treatment can be effectively managed in a post-anaesthetic care unit with improved outcomes. Most fast-track concepts include anaesthetic techniques, which are aimed at quick recovery of the patient and optimal pain therapy. In contrast to these studies, in our study all surgical patients were analysed. In the allocation of patients postoperatively, the type of anaesthesia only plays a minor role, as the PACU can provide the same level of care, as an ICU can supply. In other studies, "fast-track"-patients are identified prior to surgery by well-defined criteria and receive numerous interventions aimed at a fast recovery of the patient.

Studies report that about 12.4 to 14% of all elective surgeries are postponed [20, 21]. One major problem for many hospitals cannot be improved by the implementation of "fast-track" surgery: the deficiency of intensive care beds. This lack of capacities leads to a postponement of elective surgery or undesirable waiting times for optimal treatment for patients admitted to the emergency department after major trauma. The problem of reduced access to intensive care can be addressed with certain interventions, but these might also be responsible for increased mortality rates and length of stay [12]. The unavailability of a postoperative intensive care bed is not the only reason for the cancellation of surgery. In our institution, after the introduction of the PACU, no surgical case was cancelled due to a lack of postoperative care for the patient. The mean time from admission to the hospital to initiation of surgery dropped for all patients, independent of whether they were treated in the PACU or ICU or neither or both.

Other hospitals have introduced acuity adaptable patient care units to fast track postoperative patients in an effort to reduce hospital length of stay [22]. These novel models do not address the problem of limited ICU-bed resources though, and have little potential to reduce the number of delayed surgeries due to a lack of ICU capacities.

A worldwide study by Rothen and colleagues [23] conducted in 275 intensive care units demonstrated a considerable variability in outcomes and resource use. The secondary aim of this study was to assess whether outcome or resource use are related to ICU structure and process. In the multivariate analysis in the Rothen study, only interprofessional rounds, emergency department and geographical location were significant. The results from this study on 16,560 adults imply that some other confounding factors and not factors, such as staffing, specialists per bed or type of hospital, play an important role. In a benchmark study by Zimmerman and colleagues [24] using the data of over 350,000 patients from 108 ICUs, the hospitals with the shortest ICU and hospital stay had alternatives to intensive care, methods to facilitate patient throughput and used multiple protocols for high-volume diagnoses. The results of these studies demonstrate that only a number of interventions can be effective, when it comes to influencing the resource use and outcomes of an ICU.

A study by Rapoport and colleagues [25] investigated the length of stay data as a guide to hospital economic performance for ICU-patients and demonstrated that the first day of ICU-treatment is about four to five times more expensive than post-ICU days and more expensive than the following ICU days. The results from our study demonstrate that the patients in the ICU have longer lengths of stay and seem to be sicker and need more artificial invasive organ support (extra corporal cardiac assist devices, renal replacement therapy). This suggests a more effective use of the expensive resource ICU. The short-stay patients with stays under 24 hours are increasingly treated in the PACU and the overall length of hospital stay for all surgical patients was significantly shorter in the time period after the introduction of the PACU. At the same time, the outcome variable ICU-readmission improved. The mortality for all surgical patients did not change (data not shown).

Whether the intensive treatment in the PACU with the goal to meet the discharge criteria within 24 hours has directly influenced the overall length of hospital stay is speculative. As planned, PACU patients should meet discharge criteria at the end of the treatment time, the staff of the PACU uses various aspects of fast-track surgery to meet these goals: rapid achievement of normothermia, rapid extubation if the patient meets extubation criteria, intensive use of CPAP-therapy if indicated, fluid management to achieve fast hemodynamic stability and early oral intake of postoperative patients. Of course, patients are not discharged and are transferred to an ICU or IMCU if they do not meet the discharge criteria within this time. Ender and colleagues [15] implemented a cardiac surgery fast track treatment in the PACU and demonstrated pronounced results for shorter duration of ventilation, time in PACU or ICU and hospital length of stay, with at the same time improved outcome parameters, like mortality. This study has some differences compared to our situation: the PACU was used during daytime only for the fast-track patients and staffed by the anaesthesia department. Our PACU runs 24 hours a day and all patients in need of intensive care are treated there. The patients treated in our PACU are not selected towards specific types of anaesthetic management.

We did not directly compare our lengths of stay with other data from the literature but only within the time development, as the different health care systems make comparisons difficult. The German-DRG-system defines minimum length of stay in the hospital and hospitals receive less reimbursement if patients are discharged before these defined times, making postoperative length of stay difficult to compare. Additionally, the intensive care team has little influence on the discharge decision on the general ward.

One effect that was not investigated in our study was the impact of the PACU on vacant intensive care beds, as this is not an issue of debate in our department. With the introduction of the PACU, there is no need for the reservation of a bed within the ICU for unexpected emergency cases, as there are always capacities for unplanned or emergency department patients.

Our study differs from many other studies on the effectiveness of intensive care therapy. We used a global view from the general hospital perspective. We included all surgical patients in our evaluation, excluding only patients (n = 1,448) readmitted for the same reason after discharge from the hospital as the administrative data of these patients are combined in one case. As other authors already have noted [23], the variability in outcome and resource use is a very complex structure, which is influenced by numerous factors. We included all surgical patients, as an optimal treatment process for some patients might influence other patients, which are not directly affected. If the hospital length of stay is reduced for some patients, the hospital can use these resources for treatment of new cases and increase the volume of treated patients and perhaps influence the profit. As the base rate has changed over the study period, we used the value of the case-mix to assess the financial impact of structural changes, as the case mix index is used for determination of the revenue for the hospital. Our results demonstrate that despite the fact that surgical patients in need of intensive care stayed longer in the ICU, the overall effect was a reduction of LOS for surgical patients and an increase of case mix index per hospital day. For the subgroup of all ICU-patients, a shorter duration of hospital stay could also be demonstrated (data not shown). This enables the surgical partners to treat more patients in the same number of beds over a given time with more revenues for each hospital day.

The introduction of a PACU and the staffing with intensive care staff might shorten the hospital length-of-stay for surgical patients. The revenues for the hospital, as determined by the case mix index of the patients per hospital day, increased after the implementation of a PACU, including the staffing with an around the clock intensive care specialist. More patients can be treated in the same time, due to a better use of resources.